Picking lift

Abstract

To provide a picking lift that can suppress pallet rattling unintended by the passenger.SOLUTION: A picking lift comprises a pallet locking device with a pallet locking function, a switch to turn the pallet locking function on and off, and a height detection unit that detects the height of forks. A lock control unit of the pallet locking device controls a lock bar drive unit so as to change from a locked state to an unlocked state in which the lock bar is not pressed against the pallet only when the pallet lands in the locked state where the lock bar is pressed against the pallet, or when the lifting height of the forks falls below a specified lock lifting height. This allows the lock control unit to avoid a transition from the locked state to the unlocked state even if the palette locking function is switched from ON to OFF by the switch when the pallet is not on the ground and the fork lift height is equal to or greater than the lock lifting height.SELECTED DRAWING: Figure 4

Description

Technical Field

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[0001] The present invention relates to a picking lift.

Background Art

[0002] A picking lift is known as one of forklifts. The picking lift includes a lifting part having an operator's cab and forks extending from the operator's cab. A passenger on the picking lift ascends together with a pallet supported by the forks by boarding the operator's cab. Then, the passenger performs a picking operation between the shelf at the ascending destination and the pallet. In such a picking operation using a picking lift, suppression of rattling of the pallet is required.

[0003] Patent Document 1 discloses a picking lift provided with a pallet locking device as a device for suppressing rattling of a pallet. The pallet locking device has a lock bar provided on the lifting part. The pallet locking device has a pallet locking function of locking the pallet together with the forks that support the upper deck board of the pallet by pressing the lock bar against the lower deck board of the pallet. Further, the picking lift includes a changeover switch for switching on and off the pallet locking function. The changeover switch is operated by a passenger on the picking lift.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] During picking operations, operators of picking lifts stand up and squat down. As a result, a part of the operator's body may come into contact with the changeover switch, causing the operator to unintentionally operate the switch. The pallet locking device described in Patent Document 1 releases the pallet lock when the changeover switch is operated, switching the pallet lock function from on to off while the pallet is locked. In this case, since the operator perceives the pallet as locked, unintended rattling of the pallet occurs. [Means for solving the problem]

[0006] A picking lift to solve the above problems comprises a driver's cab and a lifting section having forks extending from the driver's cab; a pallet locking device having a lock bar provided on the lifting section and a pallet locking function that locks the pallet together with the forks when the lock bar is pressed against the lower deck board of the pallet; and a changeover switch for switching the pallet locking function on and off, wherein the picking lift comprises a lifting height detection unit for detecting the lifting height of the forks, and the pallet locking device comprises a lock bar drive unit capable of pressing the lock bar against the lower deck board, a landing detection unit used to determine whether the pallet has landed, and a lock connected to the changeover switch, the lifting height detection unit, and the landing detection unit and controlling the lock bar drive unit. The lock control unit comprises a lock control unit and a lock control unit, which can determine whether the pallet has landed based on the detection result of the landing detection unit. The lock control unit controls the lock bar drive unit so that the lock bar is released from the locked state to the unlocked state where it is not pressed against the lower deck board only when at least one of the following conditions is met: the pallet has landed or the lifting height of the fork detected by the lifting height detection unit falls below a predetermined locking height. This ensures that when the pallet has not landed and the lifting height of the fork is equal to or greater than the locking height, the pallet lock function is not released from the locked state even when the changeover switch is turned on or off.

[0007] According to the above configuration, the lock control unit controls the lock bar drive unit to switch from the locked state to the unlocked state only when at least one of the following conditions is met: the pallet touches the ground while locked, or the fork lifting height falls below the locking height. In other words, even if the pallet lock function is switched from on to off by the changeover switch while locked, the lock control unit does not control the lock bar drive unit to switch from the locked state to the unlocked state if the pallet has not touched the ground and the fork lifting height is equal to or greater than the locking height. As a result, the lock control unit avoids switching from the locked state to the unlocked state even if the pallet lock function is switched from on to off by the changeover switch when the pallet lock device is locked. Therefore, even if the pallet lock function is switched from on to off by the operator of the picking lift during picking work when the pallet lock device is locked, the pallet lock device will not be released. Thus, unintended rattling of the pallet by the operator can be suppressed.

[0008] In the picking lift described above, a pallet contact detection unit is provided, which is connected to the lock control unit and used to detect when the forks come into contact with the upper deck board of the pallet. The lock control unit detects when the forks come into contact with the upper deck board from the detection result of the pallet contact detection unit, recognizes whether the pallet lock function is on or off from the operating state of the changeover switch, and in the unlocked state, if the forks are in contact with the upper deck board, the lifting height of the forks detected by the lifting height detection unit is greater than or equal to the lock lifting height, and the pallet lock function is on, the lock bar drive unit may be controlled to move from the unlocked state to the locked state.

[0009] According to the above configuration, the lock control unit controls the lock bar drive unit to switch from the unlocked state to the locked state when the forks contact the upper deck board, the fork lifting height is greater than or equal to the locking height, and the pallet lock function is turned on. Therefore, if the changeover switch is operated in advance to turn on the pallet lock function, the pallet can be automatically locked by the pallet lock device when the forks contact the upper deck board and the fork lifting height becomes greater than or equal to the locking height.

[0010] In the picking lift described above, a material handling motor is provided for raising and lowering the lifting section, and the lifting height detection unit may consist of a rotation sensor for detecting the rotation speed of the material handling motor, a lifting height switch that switches when the lifting height of the forks reaches a predetermined reference lifting height, and a calculation unit connected to the rotation sensor and the lifting height switch, which calculates the lifting height of the forks based on the rotation speed of the material handling motor after the lifting height switch has been switched.

[0011] With the above configuration, it is easier to handle changes in the locking height compared to a case where the lifting height detection unit is a limit switch that switches when the fork's lifting height reaches the locking height. In the picking lift described above, the lock bar drive unit includes a cylinder having a cylinder tube and a piston rod movable relative to the cylinder tube, and the lock bar is pressed against the lower deck board as the amount of protrusion of the piston rod relative to the cylinder tube increases, and the pallet locking device has a cylinder detection unit connected to the lock control unit and used to determine whether the amount of protrusion of the piston rod from the cylinder tube is at its maximum, and a lock detection unit connected to the lock control unit and used to determine whether the pallet locking device is in the locked state, and the lock control unit may determine from the detection result of the cylinder detection unit whether the amount of protrusion of the piston rod from the cylinder tube is at its maximum, and from the detection result of the lock detection unit whether the pallet locking device is in the locked state, and if the amount of protrusion of the piston rod from the cylinder tube is at its maximum and the pallet locking device is not in the locked state, it may determine that the pallet has failed to lock.

[0012] With the above configuration, it is possible to detect when the pallet locking has failed. [Effects of the Invention]

[0013] According to the present invention, it is possible to suppress unintended rattling of pallets by the operator of a picking lift. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view showing a picking lift in an embodiment. [Figure 2] This is a side view showing a picking lift in an embodiment. [Figure 3] This is a block diagram showing the configuration of a picking lift in an embodiment. [Figure 4] This is a state transition diagram of the pallet locking device in an embodiment. [Figure 5] This is a perspective view showing a pallet locking device in an embodiment. [Figure 6] A side view showing the pallet locking device before the fork contacts the upper deck board. [Figure 7] A side view showing the pallet locking device in a state where the fork contacts the upper deck board. [Figure 8] A side view showing the pallet locking device in a locked state.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, an embodiment in which the picking lift is embodied will be described according to FIGS. 1 to 8. In the following description, "front", "rear", "left", "right", "upper", and "lower" refer to "front", "rear", "left", "right", "upper", and "lower" when the rider of the picking lift is facing the forward direction during driving.

[0016] <Basic Configuration of the Picking Lift> As shown in FIGS. 1 and 2, the picking lift 10 includes a vehicle body 12, a lifting part 13, and a cargo handling device 14.

[0017] The vehicle body 12 has a main body part 21 and a pair of leg parts 22. The main body part 21 is located at the front part of the picking lift 10. A driving wheel 23 is provided on the main body part 21. Further, a traveling motor 24 is provided inside the main body part 21. The traveling motor 24 rotates the driving wheel 23. Thereby, the vehicle body 12 travels. The driving wheel 23 also serves as a steering wheel. The pair of leg parts 22 extend rearward from the main body part 21. A driven wheel 25 is provided on the pair of leg parts 22.

[0018] The lifting part 13 has an operation platform 31, a pair of forks 32, and a wall part 33. The operator's platform 31 is the part where the rider of the picking lift 10 boards. The operator's platform 31 is located at the rear of the picking lift 10. The operator's platform 31 is provided between a pair of legs 22. The operator's platform 31 has an upper plate 31a and a lower plate 31b. The upper plate 31a and the lower plate 31b are arranged at intervals in the vertical direction. The upper surface of the upper plate 31a constitutes the upper surface of the operator's platform 31. The lower surface of the lower plate 31b constitutes the lower surface of the operator's platform 31.

[0019] A pair of forks 32 extend rearward from the operator's platform 31. The pair of forks 32 are arranged side by side at intervals in the left-right direction. The wall portion 33 is erected upward from the front of the operator's platform 31. The upper part of the wall portion 33 is net-shaped. Thereby, the forward visibility of the rider of the picking lift 10 is ensured and the rider is protected. A guard 34 is provided on the rear surface of the wall portion 33. The guard 34 protects the rider by surrounding the rider. Also, an instrument panel 35 is provided on the rear surface of the wall portion 33. A cargo handling lever 36 is provided on the instrument panel 35. The cargo handling lever 36 is operated when raising and lowering the lifting part 13. Also, a changeover switch 37 is provided on the instrument panel 35. Therefore, the picking lift 10 includes the changeover switch 37. The changeover switch 37 is a switch for switching on and off the pallet locking function of the pallet locking device 16 described later. The cargo handling lever 36 and the changeover switch 37 are operated by the rider.

[0020] As shown in FIG. 2, the cargo handling device 14 has a mast 41 and a mast driving unit 42 for driving the mast 41. The mast 41 is located between the main body 21 of the vehicle body 12 and the wall 33 of the lifting section 13. The mast 41 has an outer mast 41a and an inner mast 41b. The outer mast 41a is fixed to the vehicle body 12. The inner mast 41b is movable vertically relative to the outer mast 41a. A chain wheel (not shown) is provided on the upper part of the inner mast 41b. A chain (not shown) is attached to the chain wheel. One end of the chain is attached to the outer mast 41a, and the other end of the chain is attached to the driver's cab 31. When the inner mast 41b moves up and down relative to the outer mast 41a, the lifting section 13 also moves up and down.

[0021] The mast drive unit 42 includes a lift cylinder 43, a tank 44, a valve 45, a hydraulic pump 46, and a load handling motor 47. The lift cylinder 43 is a hydraulic cylinder. The inner mast 41b moves vertically relative to the outer mast 41a by supplying and discharging hydraulic fluid to the lift cylinder 43. Hydraulic fluid is stored in the tank 44. The lift cylinder 43 and the tank 44 are connected by an oil passage 48. The valve 45 is located in the oil passage 48. When the load handling lever 36 is operated, the valve 45 is open. When the load handling lever 36 is not operated, the valve 45 is closed. When the valve 45 is open, the lift cylinder 43 and the tank 44 are in communication. When the valve 45 is closed, the lift cylinder 43 and the tank 44 are not in communication.

[0022] The hydraulic pump 46 is located between the valve 45 and the tank 44 in the oil passage 48. The hydraulic pump 46 is driven by the lifting motor 47. The lifting motor 47 is driven when the lifting lever 36 is operated. The lifting motor 47 is a motor that can rotate in both directions. When the lifting motor 47 rotates in the first direction, the hydraulic pump 46 supplies the hydraulic fluid stored in the tank 44 to the lift cylinder 43. When the lifting motor 47 rotates in the second direction, which is the opposite direction to the first direction, the hydraulic pump 46 returns the hydraulic fluid filled in the lift cylinder 43 to the tank 44. In this way, the lifting motor 47 is a motor for raising and lowering the lifting section 13.

[0023] <Head height detection unit> As shown in Figure 3, the picking lift 10 is equipped with a lifting height detection unit 15. The lifting height detection unit 15 detects the lifting height of the forks 32, which is the height from the ground to the top surface of the forks 32. In this embodiment, the lifting height detection unit 15 is composed of a rotation sensor 51, a lifting height switch 52, and a vehicle control unit 53.

[0024] The rotation sensor 51 detects the rotation speed of the cargo handling motor 47. The lifting height switch 52 is a switch that turns on when the lifting height of the fork 32 reaches a predetermined reference lifting height. In this embodiment, the lifting height switch 52 is a limit switch. The lifting height switch 52 is turned on when the lifting height of the fork 32 is equal to or greater than the reference lifting height. The lifting height switch 52 is turned off when the lifting height of the fork 32 is less than the reference lifting height. The reference lifting height is set to, for example, 500 mm. Alternatively, the lifting height switch 52 may be a switch that is turned on when the lifting height of the fork 32 is less than the reference lifting height and turned off when the lifting height of the fork 32 is equal to or greater than the reference lifting height.

[0025] The vehicle control unit 53 comprises a processor and a memory unit. The processor may be, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a DSP (Digital Signal Processor). The memory unit includes RAM (Random Access Memory) and ROM (Read Only Memory). The memory unit stores a program for operating the picking lift 10. The memory unit can be said to store program code or instructions configured to cause the processor to execute processing. The memory unit, i.e., the computer-readable medium, includes any available medium accessible by a general-purpose or dedicated computer. The vehicle control unit 53 may be composed of hardware circuits such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The processing circuit, the vehicle control unit 53, may include one or more processors operating according to a computer program, one or more hardware circuits such as an ASIC or FPGA, or a combination thereof.

[0026] The vehicle control unit 53 is connected to the rotation sensor 51 and the lifting height switch 52. The vehicle control unit 53 determines that the lifting height of the forks 32 is the reference lifting height when the lifting height switch 52 is switched. The vehicle control unit 53 obtains the rotation speed of the cargo handling motor 47 from the rotation sensor 51. The vehicle control unit 53 calculates the amount of lifting of the lifting section 13 after the lifting height switch 52 is switched, based on the rotation speed of the cargo handling motor 47 after the lifting height switch 52 is switched. The vehicle control unit 53 calculates the lifting height of the forks 32 by adding or subtracting the amount of lifting of the lifting section 13 calculated from the reference lifting height. Therefore, the vehicle control unit 53 is a calculation unit that calculates the lifting height of the forks 32 based on the rotation speed of the cargo handling motor 47 after the lifting height switch 52 is switched.

[0027] <Pallet locking device> As shown in Figures 3 and 5, the picking lift 10 is equipped with a pallet locking device 16 that has a pallet locking function for locking pallets P. The pallet locking device 16 includes a lock bar 60 and a lock bar drive unit 70. The pallet locking device 16 also includes a lock control unit 80, a pallet contact detection unit 81, a lock release detection unit 82, a cylinder detection unit 83, and a spring detection unit 84 which serves as both a lock detection unit and a landing detection unit.

[0028] As shown in Figures 5 and 6, the lock bar 60 and the lock bar drive unit 70 are provided on the driver's cab 31 of the lifting unit 13. The driver's cab 31 has a pair of first mounting parts 311 and a pair of second mounting parts 312 for attaching the lock bar 60 and the lock bar drive unit 70 to the driver's cab 31. The pair of first mounting parts 311 and the pair of second mounting parts 312 protrude from the upper surface of the lower plate 31b of the driver's cab 31. The pair of first mounting parts 311 are spaced apart in the left-right direction. The pair of second mounting parts 312 are spaced apart in the left-right direction. The pair of second mounting parts 312 support a support shaft 38 that extends in the left-right direction.

[0029] The lock bar 60 has a bar body 61, a pair of claw portions 62, a pair of mounting pieces 63, and an extension portion 64. The bar body 61 extends in the left-right direction. The bar body 61 is located behind the lower plate 31b of the driver's cab 31.

[0030] A pair of claw portions 62 are provided on the lower surface of the bar body 61. The pair of claw portions 62 are located at both ends of the bar body 61 in the left-right direction. The pair of claw portions 62 extend rearward from the bar body 61. As shown in Figure 1, the pair of claw portions 62 extend rearward from the driver's cab 31. The pair of claw portions 62 are located between the pair of forks 32.

[0031] A pair of mounting pieces 63 are provided on the lower surface of the bar body 61. The pair of mounting pieces 63 extend forward from the bar body 61. The pair of mounting pieces 63 are spaced apart in the left-right direction. The support shaft 38 passes through the pair of mounting pieces 63. The lock bar 60 is supported by the support shaft 38 so as to be able to swing in the vertical direction.

[0032] The extension portion 64 extends forward from the bar body 61. The extension portion 64 is positioned in front of the pair of mounting pieces 63. When the lock bar 60 swings so that the pair of claw portions 62 descend, the extension portion 64 rises. Conversely, when the lock bar 60 swings so that the claw portions 62 rise, the extension portion 64 descends.

[0033] The lock bar drive unit 70 can press a pair of claws 62 of the lock bar 60 against the upper surface of the lower deck board D2 of the pallet P by swinging the lock bar 60 vertically. The lock bar drive unit 70 has an actuator 71 and a link mechanism 72. The lock bar drive unit 70 is located between the upper plate 31a and the lower plate 31b of the driver's cab 31. The lock bar drive unit 70 is built into the driver's cab 31.

[0034] The actuator 71 of this embodiment is an electrically powered cylinder having a cylinder 73 and a cylinder motor 74. The actuator 71 is arranged such that the cylinder 73 extends in the front-rear direction. The cylinder 73 has a cylinder tube 73a and a piston rod 73b that is movable in the front-rear direction relative to the cylinder tube 73a. The piston rod 73b is moved in the front-rear direction relative to the cylinder tube 73a by the cylinder motor 74.

[0035] The link mechanism 72 includes a first link arm 75, a second link arm 76, and a connecting member 77. The first link arm 75 is positioned between the pair of first mounting portions 311. The lower end of the first link arm 75 is connected to the pair of first mounting portions 311. The first link arm 75 is pivotable in the front-rear direction relative to the first mounting portions 311. The upper end of the first link arm 75 is connected to the tip of the piston rod 73b.

[0036] The second link arm 76 is located between a pair of second mounting portions 312. The support shaft 38 passes through the lower end of the second link arm 76. The second link arm 76 is supported by the support shaft 38 so as to be able to swing in the front-rear direction. The bar body 61 of the lock bar 60 is positioned on the swing trajectory of the second link arm 76. More specifically, the bar body 61 is positioned so as to contact the second link arm 76 when the second link arm 76 swings backward.

[0037] The connecting member 77 connects the first link arm 75 and the second link arm 76 in the front-rear direction. Specifically, the front end of the connecting member 77 is connected between the upper and lower ends of the first link arm 75. The rear end of the connecting member 77 is connected to the upper end of the second link arm 76. The connecting member 77 includes a spring 77a that is expandable and contractible in the front-rear direction.

[0038] As shown in Figure 6, during the loading and unloading operation of the picking lift 10, a pair of forks 32 are inserted into the fork insertion openings Pf of the pallet P. The fork insertion openings Pf are separated by the lower surface of the upper deck board D1 and the upper surface of the lower deck board D2 of the pallet P. A pair of claws 62 of the lock bar 60 are also inserted into the fork insertion openings Pf. The lock bar 60 extends horizontally.

[0039] As shown in Figure 7, the lifting unit 13 rises with the pair of forks 32 and the pair of claws 62 inserted into the fork insertion openings Pf. The pair of claws 62 then contact the lower surface of the upper deck board D1 of the pallet P. As described above, the lock bar 60 is configured to swing vertically by the support shaft 38. Therefore, the lock bar 60 swings so that the pair of claws 62 are pushed down by the upper deck board D1, causing the pair of claws 62 to descend and the extension 64 to rise. The pair of forks 32 also contact the lower surface of the upper deck board D1 of the pallet P. The lifting unit 13 lifts the pallet P by rising with the pair of forks 32 supporting the upper deck board D1.

[0040] The pallet locking device 16 can be in a locked state or an unlocked state. Figures 6 and 7 show the pallet locking device 16 in the unlocked state. The protrusion of the piston rod 73b from the cylinder tube 73a is minimized. The pair of claws 62 of the locking bar 60 are not pressed against the upper surface of the lower deck board D2 of the pallet P. Therefore, the pallet P can move upward. In other words, the pallet P is not locked.

[0041] Figure 8 shows the pallet locking device 16 in the locked state. The amount of protrusion of the piston rod 73b from the cylinder tube 73a is greater than when it is unlocked. The pair of claws 62 of the lock bar 60 are pressed against the upper surface of the lower deck board D2 of the pallet P. The upper deck board D1 is supported by a pair of forks 32, and the pair of claws 62 are pressed against the lower deck board D2, thereby restricting the vertical movement of the pallet P. In other words, the pallet P is locked.

[0042] As shown in Figure 4, the pallet locking device 16 transitions from an unlocked state to a locked state via a first transition operation. The first transition operation is an operation in which the piston rod 73b moves backward relative to the cylinder tube 73a so that the amount of protrusion of the piston rod 73b from the cylinder tube 73a increases.

[0043] As shown in Figure 8, when the piston rod 73b moves backward relative to the cylinder tube 73a, the first link arm 75 connected to the piston rod 73b swings backward. When the first link arm 75 swings backward, the connecting member 77 connected to the first link arm 75 also moves backward. When the connecting member 77 moves backward, the second link arm 76 connected to the connecting member 77 also swings backward. The backward swing of the second link arm 76 pushes down the bar body 61 of the lock bar 60. As a result, the lock bar 60 swings so that the pair of claw portions 62 descend and the extension portion 64 rises.

[0044] The lowered pair of claws 62 contact the upper surface of the lower deck board D2 of the pallet P. Even after the pair of claws 62 have contacted the upper surface of the lower deck board D2, as the piston rod 73b moves backward, the pair of claws 62 are pressed against the upper surface of the lower deck board D2. As a result, the pallet locking device 16 is locked. The member of the connecting member 77 behind the spring 77a cannot move any further backward, so the spring 77a is compressed. In this way, when the pallet locking device 16 is locked by the lock bar 60 being pressed against the upper surface of the lower deck board D2, the amount of compression of the spring 77a increases.

[0045] As shown in Figure 4, the pallet locking device 16 transitions from the locked state to the unlocked state via a second transition operation. The second transition operation is an operation in which the piston rod 73b moves forward relative to the cylinder tube 73a so that the amount of protrusion of the piston rod 73b from the cylinder tube 73a decreases.

[0046] As shown in Figures 6 and 7, when the piston rod 73b moves forward relative to the cylinder tube 73a, the first link arm 75 connected to the piston rod 73b also swings forward. When the first link arm 75 swings forward, the compressed state of the spring 77a returns to its original state, and the connecting member 77 connected to the first link arm 75 also moves forward. When the connecting member 77 moves forward, the second link arm 76 connected to the connecting member 77 also swings forward. When the second link arm 76 swings forward, the lock bar 60 is no longer pushed down by the second link arm 76. Therefore, the lock bar 60 becomes able to swing such that the pair of claw portions 62 rise and the extension portion 64 descends.

[0047] The lock control unit 80 comprises a processor and a memory unit. For example, a CPU, GPU, or DSP may be used as the processor. The memory unit includes RAM and ROM. The memory unit stores a program for operating the pallet lock device 16. The memory unit can be said to store program code or instructions configured to cause the processor to execute processing. The memory unit, i.e., the computer-readable medium, includes any available medium accessible by a general-purpose or dedicated computer. The lock control unit 80 may also be composed of hardware circuits such as ASICs or FPGAs. The lock control unit 80, which is a processing circuit, may include one or more processors operating according to a computer program, one or more hardware circuits such as ASICs or FPGAs, or a combination thereof.

[0048] As shown in Figure 3, the lock control unit 80 is connected to the changeover switch 37. The lock control unit 80 recognizes whether the pallet lock function is on or off from the operating state of the changeover switch 37. The lock control unit 80 is connected to the lifting height detection unit 15, the pallet contact detection unit 81, the lock release detection unit 82, the cylinder detection unit 83, and the spring detection unit 84. The lock control unit 80 recognizes the state of the pallet lock device 16 and the pallet P from the detection results of each detection unit. The lock control unit 80 is also connected to the lock bar drive unit 70. The lock control unit 80 controls the operation of the pallet lock device 16 by controlling the cylinder motor 74 of the lock bar drive unit 70. The control of the pallet lock device 16 will be described later.

[0049] The pallet contact detection unit 81 is used to detect when a pair of forks 32 make contact with the lower surface of the upper deck board D1 of the pallet P. In this embodiment, the pallet contact detection unit 81 is a limit switch. The pallet contact detection unit 81 has a pallet detection bar 81a. The pallet detection bar 81a is located below the extension 64. The pallet contact detection unit 81 is ON when the pallet detection bar 81a is pressed down by the extension 64. The pallet contact detection unit 81 is OFF when the pallet detection bar 81a is not pressed down by the extension 64.

[0050] As described above, the lock bar 60 extends horizontally before the pair of forks 32 contact the lower surface of the upper deck board D1. At this time, the pallet detection bar 81a is pushed down by the extension 64, so the pallet contact detection unit 81 is in the ON state. When the pair of forks 32 contact the lower surface of the upper deck board D1, the lock bar 60 swings so that the extension 64 rises. As a result, the pallet detection bar 81a is no longer pushed down by the extension 64, and the pallet contact detection unit 81 switches from the ON state to the OFF state.

[0051] The lock control unit 80 detects from the detection result of the pallet contact detection unit 81 that the pair of forks 32 have come into contact with the lower surface of the upper deck board D1. The lock control unit 80 also detects that the pair of forks 32 have come into contact with the lower surface of the upper deck board D1 when the pallet contact detection unit 81 changes from the ON state to the OFF state.

[0052] The unlock detection unit 82 is used to determine whether or not the pallet locking device 16 is in an unlocked state. In this embodiment, the unlock detection unit 82 is a limit switch. The unlock detection unit 82 has a link detection bar 82a. The link detection bar 82a is positioned on the swing trajectory of the first link arm 75. Specifically, the link detection bar 82a is positioned so as to contact the first link arm 75 when the first link arm 75 swings forward. The unlock detection unit 82 is turned ON when the link detection bar 82a is pressed by the first link arm 75. The unlock detection unit 82 is turned OFF when the link detection bar 82a is not pressed by the first link arm 75.

[0053] As described above, when the pallet locking device 16 is unlocked, that is, when the amount of protrusion of the piston rod 73b from the cylinder tube 73a is at its minimum, the first link arm 75 is tilted forward. At this time, the link detection bar 82a is pressed by the first link arm 75, so the unlock detection unit 82 is in the ON state.

[0054] The lock control unit 80 determines whether the pallet lock device 16 is in an unlocked state based on the detection result of the unlock detection unit 82. The lock control unit 80 determines that the pallet lock device 16 is in an unlocked state when the unlock detection unit 82 is ON. The lock control unit 80 determines that the pallet lock device 16 is not in an unlocked state when the unlock detection unit 82 is OFF.

[0055] The cylinder detection unit 83 is used to determine whether the amount of protrusion of the piston rod 73b from the cylinder tube 73a is at its maximum. In this embodiment, the cylinder detection unit 83 is, for example, a current sensor. The cylinder detection unit 83 detects the output current of the cylinder motor 74. When the amount of protrusion of the piston rod 73b from the cylinder tube 73a is at its maximum, the output current of the cylinder motor 74 increases.

[0056] The lock control unit 80 determines from the detection result of the cylinder detection unit 83 whether the amount of protrusion of the piston rod 73b from the cylinder tube 73a is at its maximum. The lock control unit 80 determines that the amount of protrusion of the piston rod 73b from the cylinder tube 73a is at its maximum when the output current of the cylinder motor 74 detected by the cylinder detection unit 83 is equal to or greater than a predetermined current threshold. The lock control unit 80 determines that the amount of protrusion of the piston rod 73b from the cylinder tube 73a is not at its maximum when the output current of the cylinder motor 74 detected by the cylinder detection unit 83 is less than a predetermined current threshold.

[0057] The spring detection unit 84 is used to determine whether the pallet locking device 16 is locked or not. The spring detection unit 84 is also used to determine whether the pallet P has landed on the floor, shelf, loading platform, etc. The spring detection unit 84 detects the amount of compression of the spring 77a. In this embodiment, the spring detection unit 84 is a potentiometer.

[0058] As described above, when the pallet locking device 16 is locked, the amount of compression of the spring 77a increases. The lock control unit 80 determines whether or not the pallet locking device 16 is locked based on the detection result of the spring detection unit 84. The lock control unit 80 determines that the pallet locking device 16 is locked if the amount of compression of the spring 77a detected by the spring detection unit 84 is equal to or greater than a predetermined lock determination threshold. The lock control unit 80 determines that the pallet locking device 16 is not locked if the amount of compression of the spring 77a detected by the spring detection unit 84 is less than the lock determination threshold.

[0059] When the lifting section 13 descends and the pallet P lands, the pair of forks 32 separate from the underside of the upper deck board D1 of the pallet P. Also, as the pair of claws 62 are pushed up by the lower deck board D2, the lock bar 60 swings so that the pair of claws 62 rises. As a result, the second link arm 76 swings forward. At this time, the member of the connecting member 77 in front of the spring 77a cannot move forward, so the spring 77a is compressed. Note that the spring 77a is already compressed when the pallet locking device 16 is locked, so the amount of compression of the spring 77a will increase further.

[0060] The lock control unit 80 determines whether or not the pallet P has landed based on the detection result of the spring detection unit 84. The lock control unit 80 determines that the pallet P has landed if the amount of compression of the spring 77a detected by the spring detection unit 84 is equal to or greater than a predetermined threshold for determining landing. The threshold for determining landing is set to a value greater than the threshold for determining lock. The lock control unit 80 determines that the pallet P has not landed if the amount of compression of the spring 77a detected by the spring detection unit 84 is less than the threshold for determining landing.

[0061] <Control of pallet locking device> The control of the pallet locking device 16 by the lock control unit 80 will be described in detail below. As shown in Figure 4, when the pallet locking device 16 is in the unlocked state and all of the first, second, and third locking conditions are met, it transitions to the locked state via a first transition operation.

[0062] First locking condition: Fork 32 is in contact with the upper deck board D1 of pallet P. Second locking condition: The lifting height of the fork 32 is greater than or equal to the predetermined locking lifting height. Third lock condition: The pallet lock function is turned on.

[0063] Whether or not each locking condition is met is determined by the lock control unit 80. The lock control unit 80 determines whether the first lock condition is met based on the detection result of the pallet contact detection unit 81. The lock control unit 80 determines that the first lock condition is met when the pallet contact detection unit 81 changes from the ON state to the OFF state.

[0064] The lock control unit 80 determines whether the second lock condition is met based on the detection result of the lifting height detection unit 15. In this embodiment, the lock lifting height is set to a lifting height of 500 mm or less. The lock control unit 80 determines that the second lock condition is met if the lifting height of the fork 32 detected by the lifting height detection unit 15 is equal to or greater than the lock lifting height. On the other hand, the lock control unit 80 determines that the second lock condition is not met if the lifting height of the fork 32 detected by the lifting height detection unit 15 is less than the lock lifting height.

[0065] The lock control unit 80 determines whether the third lock condition is met based on the operating state of the changeover switch 37. If the changeover switch 37 is operated in the direction that turns on the pallet lock function, the lock control unit 80 determines that the third lock condition is met. On the other hand, if the changeover switch 37 is operated in the direction that turns off the pallet lock function, the lock control unit 80 determines that the third lock condition is not met.

[0066] Then, if the lock control unit 80 determines that all of the first to third lock conditions are met, it causes the actuator 71 to perform a first transition operation to transition from the unlocked state to the locked state. Specifically, the lock control unit 80 controls the cylinder motor 74 so that the piston rod 73b moves backward.

[0067] In this embodiment, if the pallet locking device 16 determines that locking the pallet P has failed during the first transition operation, it transitions to the second transition operation. That is, the pallet locking device 16 stops the transition from the unlocked state to the locked state and then returns to the unlocked state.

[0068] The lock control unit 80 determines whether or not the lock of pallet P has failed. The lock control unit 80 determines that the lock of pallet P has failed if the pallet locking device 16 is not in a locked state when the amount of protrusion of the piston rod 73b from the cylinder tube 73a is at its maximum. Specifically, the lock control unit 80 determines that the lock of pallet P has failed if the current value detected by the cylinder detection unit 83 is greater than or equal to the current threshold, and the compression amount of the spring 77a detected by the spring detection unit 84 is less than the lock determination threshold. If the lock control unit 80 determines that the lock of pallet P has failed, it causes the actuator 71 to perform a second transition operation. Specifically, the lock control unit 80 controls the cylinder motor 74 so that the piston rod 73b moves forward.

[0069] The pallet locking device 16 transitions to the unlocked state via a second transition operation when at least one of the first unlock condition and the second unlock condition is met while it is in the locked state. Note that "at least one of the first unlock condition and the second unlock condition" refers to "only the first unlock condition," "only the second unlock condition," or "both the first and second unlock conditions."

[0070] First unlocking condition: The lifting height of fork 32 is less than the locking lifting height. Second unlock condition: Palette P has landed. Whether or not each unlocking condition is met is determined by the lock control unit 80.

[0071] The lock control unit 80 determines whether the first unlock condition is met based on the detection result of the lifting height detection unit 15. The lock control unit 80 determines that the first unlock condition is met if the lifting height of the fork 32 detected by the lifting height detection unit 15 is less than a predetermined locking height. On the other hand, the lock control unit 80 determines that the first unlock condition is not met if the lifting height of the fork 32 detected by the lifting height detection unit 15 is equal to or greater than the locking height.

[0072] The lock control unit 80 determines whether the second unlock condition is met based on the detection result of the spring detection unit 84. The lock control unit 80 determines that the second unlock condition is met if the compression amount of the spring 77a detected by the spring detection unit 84 is equal to or greater than the threshold for landing determination. The lock control unit 80 determines that the second unlock condition is not met if the compression amount of the spring 77a detected by the spring detection unit 84 is less than the threshold for landing determination.

[0073] When the lock control unit 80 determines that at least one of the first unlock condition and the second unlock condition is met, it causes the actuator 71 to perform a second transition operation in order to transition from the locked state to the unlocked state. Specifically, the lock control unit 80 controls the cylinder motor 74 so that the piston rod 73b moves forward.

[0074] [Operation and Effects of This Embodiment] The operation and effects of this embodiment will now be explained. (1) The lock control unit 80 controls the lock bar drive unit 70 to switch from the locked state to the unlocked state only when at least one of the following conditions is met: when the pallet P lands on the ground while the lock is engaged, or when the lifting height of the forks 32 falls below a predetermined locking height. In other words, even if the pallet lock function is switched from on to off by the changeover switch 37 while the lock is engaged, the lock control unit 80 does not control the lock bar drive unit 70 to switch from the locked state to the unlocked state if the pallet P has not landed on the ground and the lifting height of the forks 32 is equal to or greater than the locking height. As a result, the lock control unit 80 avoids switching from the locked state to the unlocked state even if the pallet lock function is switched from on to off by the changeover switch 37 when the pallet lock device 16 is engaged. Therefore, it is possible to suppress rattling of the pallet P that is not intended by the passenger.

[0075] (2) When the lock control unit 80 is in the unlocked state, if the fork 32 makes contact with the upper deck board D1 and the lifting height of the fork 32 is greater than or equal to the locking height, and the pallet lock function is turned on, it controls the lock bar drive unit 70 to change from the unlocked state to the locked state. With this configuration, if the passenger operates the changeover switch 37 in advance to turn on the pallet lock function, the pallet lock device 16 can automatically lock the pallet P when the fork 32 makes contact with the upper deck board D1 and the lifting height of the fork 32 becomes greater than or equal to the locking height.

[0076] (3) The lifting height detection unit 15 consists of a rotation sensor 51, a lifting height switch 52, and a vehicle control unit 53. The rotation sensor 51 detects the rotation speed of the cargo handling motor 47. The lifting height switch 52 switches when the lifting height of the forks 32 reaches a predetermined reference lifting height. The vehicle control unit 53 is connected to the lifting height switch 52 and the rotation sensor 51. The vehicle control unit 53 calculates the lifting height of the forks 32 based on the rotation speed of the cargo handling motor 47 after the lifting height switch 52 has been switched. With this configuration, it is easier to respond when the lock lifting height is changed compared to a case where the lifting height detection unit 15 is a limit switch that switches when the lifting height of the forks 32 reaches a lock lifting height.

[0077] (4) The lock control unit 80 determines that the lock of the pallet P has failed if the pallet locking device 16 is not in a locked state when the amount of protrusion of the piston rod 73b from the cylinder tube 73a is at its maximum. With this configuration, it is possible to detect that the lock of the pallet P has failed.

[0078] (5) The spring detection unit 84 is both a lock detection unit and a landing detection unit. Therefore, the configuration of the pallet locking device 16 can be simplified compared to the case where the lock detection unit and the landing detection unit are provided separately.

[0079] [Example of changes] The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0080] ○ The specific configuration of the lifting height detection unit 15 may be changed as appropriate. The lifting height detection unit 15 may be, for example, a limit switch that switches when the lifting height of the fork 32 reaches the locked lifting height.

[0081] ○ The specific configuration of the pallet contact detection unit 81 may be changed as appropriate. The pallet contact detection unit 81 may be, for example, a magnetic sensor that detects the magnetism of a magnet attached to the tip of the extension 64.

[0082] ○ The specific configuration of the unlock detection unit 82 may be changed as appropriate. ○ The specific configuration of the cylinder detection unit 83 may be changed as appropriate. ○ The specific configuration of the spring detection unit 84 may be changed as appropriate.

[0083] ○ The lock detection unit and the landing detection unit may be provided separately. ○ The lock control unit 80 does not need to determine whether or not the locking of the pallet P has failed.

[0084] ○ The lock control unit 80 may transmit the status of the pallet locking device 16 to the vehicle control unit 53. The vehicle control unit 53 may display the received status of the pallet locking device 16 on a display (not shown). In this case, the operator of the picking lift 10 can understand the status of the pallet locking device 16 by checking the display.

[0085] ○ The picking lift 10 is not limited to a type in which the main body 21 is located on the front side in the forward direction and the driver's cab 31 is located on the rear side. The picking lift 10 may also be of a type in which the driver's cab 31 is located on the front side in the forward direction and the main body 21 is located on the rear side. In this case, the front-rear direction will be the opposite direction to the front-rear direction of the above embodiment. The instrument panel 35 is provided on the guard 34.

[0086] [Note] The technical concepts that can be understood from each of the above embodiments and their modifications are described below. [1] A picking lift comprising: a driver's cab and a lifting section having forks extending from the driver's cab; a pallet locking device having a lock bar provided on the lifting section and a pallet locking function that locks the pallet together with the forks when the lock bar is pressed against the lower deck board of the pallet; and a changeover switch for switching the pallet locking function on and off, wherein the picking lift comprises a lifting height detection unit for detecting the lifting height of the forks, the pallet locking device comprising: a lock bar drive unit capable of pressing the lock bar against the lower deck board; a landing detection unit used to determine whether or not the pallet has landed; and a lock control unit connected to the changeover switch, the lifting height detection unit, and the landing detection unit and controlling the lock bar drive unit, and the lock The picking lift is characterized in that the control unit can determine whether or not the pallet has landed based on the detection result of the landing detection unit, and in the locked state in which the lock bar is pressed against the lower deck board, the lock bar drive unit is controlled to move from the locked state to an unlocked state in which the lock bar is not pressed against the lower deck board only when at least one of the following conditions is met: the pallet has landed or the lifting height of the forks detected by the lifting height detection unit falls below a predetermined locking height, thereby preventing the pallet lock function from moving from the locked state to the unlocked state even when the changeover switch is turned off, if the pallet has not landed and the lifting height of the forks is equal to or greater than the locking height.

[0087] [2] A picking lift according to [1], comprising a pallet contact detection unit connected to the lock control unit and used to detect when the forks have come into contact with the upper deck board of the pallet, wherein the lock control unit detects when the forks have come into contact with the upper deck board from the detection result of the pallet contact detection unit, recognizes whether the pallet lock function is on or off from the operating state of the changeover switch, and controls the lock bar drive unit to change from the unlocked state to the locked state when, in the unlocked state, the forks are in contact with the upper deck board, the lifting height of the forks detected by the lifting height detection unit is greater than or equal to the lock lifting height, and the pallet lock function is on.

[0088] [3] A picking lift according to [1] or [2], comprising a cargo handling motor for raising and lowering the lifting section, wherein the lifting height detection unit comprises a rotation sensor for detecting the rotation speed of the cargo handling motor, a lifting height switch that switches when the lifting height of the forks reaches a predetermined reference lifting height, and a calculation unit connected to the rotation sensor and the lifting height switch, which calculates the lifting height of the forks based on the rotation speed of the cargo handling motor after the lifting height switch has been switched.

[0089] [4] The picking lift according to any one of [1] to [3], wherein the lock bar drive unit includes a cylinder having a cylinder tube and a piston rod movable relative to the cylinder tube, and the lock bar is pressed against the lower deck board as the amount of protrusion of the piston rod relative to the cylinder tube increases, and the pallet locking device has a cylinder detection unit connected to the lock control unit and used to determine whether the amount of protrusion of the piston rod from the cylinder tube is at its maximum, and a lock detection unit connected to the lock control unit and used to determine whether the pallet locking device is in the locked state, wherein the lock control unit determines from the detection result of the cylinder detection unit whether the amount of protrusion of the piston rod from the cylinder tube is at its maximum, and determines from the detection result of the lock detection unit whether the pallet locking device is in the locked state, and determines that the pallet has failed to lock if the amount of protrusion of the piston rod from the cylinder tube is at its maximum and the pallet locking device is not in the locked state. [Explanation of symbols]

[0090] 10... Picking lift, 13... Lifting unit, 15... Lifting height detection unit, 16... Pallet locking device, 31... Driver's cab, 32... Fork, 37... Changeover switch, 47... Cargo handling motor, 51... Rotation sensor, 52... Lifting height switch, 53... Vehicle control unit as calculation unit, 60... Lock bar, 70... Lock bar drive unit, 73... Cylinder, 73a... Cylinder tube, 73b... Piston rod, 80... Lock control unit, 81... Pallet contact detection unit, 83... Cylinder detection unit, D1... Upper deck board, D2... Lower deck board, P... Pallet.

Claims

1. A driver's cab and a lifting section having a fork extending from the driver's cab, A pallet locking device having a lock bar provided in the lifting section, the lock bar being pressed against the lower deck board of the pallet to lock the pallet together with the forks, A toggle switch to turn the aforementioned pallet lock function on or off, A picking lift equipped with, The system includes a lifting height detection unit that detects the lifting height of the fork, The pallet locking device is A lock bar drive unit capable of pressing the lock bar against the lower deck board, A landing detection unit used to determine whether or not the pallet has landed, The system includes the aforementioned changeover switch, the aforementioned lift height detection unit, and a lock control unit connected to the aforementioned landing detection unit and which controls the lock bar drive unit, The lock control unit, From the detection result of the landing detection unit, it is possible to determine whether or not the pallet has landed. A picking lift characterized in that, in the locked state in which the lock bar is pressed against the lower deck board, the lock bar drive unit is controlled to move from the locked state to an unlocked state in which the lock bar is not pressed against the lower deck board only when at least one of the following occurs: the pallet has landed or the lifting height of the forks detected by the lifting height detection unit falls below a predetermined locking height, and when the pallet lock function is switched from on to off by the changeover switch, the lock bar drive unit is controlled to move from the locked state to an unlocked state in which the lock bar is not pressed against the lower deck board, and when the pallet has not landed and the lifting height of the forks is equal to or greater than the locking height, the lock bar drive unit is controlled to move from the locked state to an unlocked state in which the lock bar is at least one of the following occurs, the lock bar drive unit is controlled to move from the locked state to an unlocked state in which the lock bar is pressed against the lower deck board, and when the lock bar is pressed against the lower deck board, in the locked state in which the lock bar is pressed against the lower deck board, the lock bar drive unit is controlled to move from the locked state to an unlocked state in which the lock bar is pressed against the lower deck board, and when at least one of the following occurs,

2. It includes a pallet contact detection unit connected to the lock control unit and used to detect when the fork has come into contact with the upper deck board of the pallet, The lock control unit, From the detection result of the pallet contact detection unit, it is detected that the fork has come into contact with the upper deck board. The on / off status of the pallet lock function is recognized from the operating state of the aforementioned changeover switch. The picking lift according to claim 1, wherein, in the unlocked state, the fork is in contact with the upper deck board, the lifting height of the fork detected by the lifting height detection unit is equal to or greater than the locking height, and the pallet lock function is turned on, the lock bar drive unit is controlled to change from the unlocked state to the locked state.

3. The lifting section is equipped with a cargo handling motor for raising and lowering it. The aforementioned lift height detection unit is A rotation sensor for detecting the rotation speed of the cargo handling motor, A lifting height switch that activates when the lifting height of the fork reaches a predetermined standard lifting height, A calculation unit connected to the rotation sensor and the lifting switch calculates the lifting height of the fork based on the rotation speed of the cargo handling motor after the lifting switch is switched, A picking lift according to claim 1, comprising the above.

4. The lock bar drive unit includes a cylinder having a cylinder tube and a piston rod movable relative to the cylinder tube. As the amount of protrusion of the piston rod relative to the cylinder tube increases, the lock bar is pressed against the lower deck board. The pallet locking device is A cylinder detection unit connected to the lock control unit and used to determine whether the amount of protrusion of the piston rod from the cylinder tube is at its maximum, A lock detection unit connected to the lock control unit and used to determine whether the pallet lock device is in the locked state, It has, The lock control unit, From the detection result of the cylinder detection unit, it is determined whether or not the amount of protrusion of the piston rod from the cylinder tube is at its maximum. Based on the detection result of the lock detection unit, it is determined whether or not the pallet locking device is in the locked state. The picking lift according to claim 1, wherein if the pallet locking device is not in the locked state when the amount of protrusion of the piston rod from the cylinder tube is at its maximum, it is determined that the pallet has failed to lock.

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