Loading platform lifting device

Abstract

To prevent a cargo receiving platform from swinging downward when a worker gets on or off a cargo box using the platform as a foothold. [Solution] The loading platform lifting device 10 includes a lift cylinder 30, a slide cylinder 32, and a control device 70. The lift cylinder 30 raises and lowers the loading platform. The slide cylinder 32 moves the loading platform in the forward and backward directions. The control device 70 controls the operation of the lift cylinder 30 and the slide cylinder 32. The lift cylinder 30 is a hydraulic cylinder. When the loading platform is stopped in the extended position or the step use position, the control device 70 controls the hydraulic pressure of the lift cylinder 30 in a direction that raises the loading platform so that the height of the loading platform is maintained at a predetermined height.

Description

[Technical Field]

[0001] The present invention relates to a loading platform lifting device. [Background technology]

[0002] Patent Document 1 discloses a loading platform lifting device mounted on the rear of a vehicle, in which the loading platform can move in the fore-and-aft direction of the vehicle between a working position and a storage position. This loading platform lifting device has a control unit that restricts the fore-and-aft movement of the loading platform when the loading platform reaches an intermediate position. Here, the working position refers to the fore-and-aft position of the loading platform when it moves up and down between a cargo box and the ground at the rear of the vehicle. The storage position refers to the fore-and-aft position of the loading platform when it is stored under the vehicle. The intermediate position refers to the fore-and-aft position of the loading platform forward of the working position and when it protrudes from the rear end of the cargo box toward the rear of the vehicle.

[0003] Furthermore, Patent Document 1 describes that the receiving platform is used as a foothold when a worker gets on and off the cargo box. When a worker uses the receiving platform as a foothold to get on and off the cargo box, it is preferable that the receiving platform be in an intermediate position. According to Patent Document 1, by using the above-mentioned receiving platform lifting device, the receiving platform automatically stops when it reaches an intermediate position from the storage position, so that the worker can easily and reliably use the receiving platform as a foothold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6357450 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a worker uses the loading platform as a foothold to get on or off a cargo box, the loading platform may swing downward due to the worker's weight. That is, when the worker stands on the loading platform, the loading platform may become unsteady. The present invention has been made in consideration of the above points, and its purpose is to prevent the loading platform from swinging downward when a worker uses the loading platform as a foothold to get on or off a cargo box. [Means for solving the problem]

[0006] The loading platform lifting device of the present invention includes a guide rail provided on the bottom of a vehicle body and extending in the fore-and-aft direction, a slider provided movably along the guide rail, an arm mechanism rotatably connected to the slider, a loading platform rotatably connected to the tip of the arm mechanism, a lift cylinder that raises and lowers the loading platform by rotating the arm mechanism, a slide cylinder that moves the slider in the fore-and-aft direction to move the loading platform in the fore-and-aft direction between a stored position where the entire loading platform overlaps with the vehicle body as viewed from above and an extended position where the entire loading platform does not overlap with the vehicle body as viewed from above, and a control device that controls the operation of the lift cylinder and the slide cylinder. The lift cylinder is a hydraulic cylinder. When the loading platform is stopped at the pulled-out position or at a step-use position where no part of the loading platform overlaps with the vehicle body when viewed from above, the control device controls the hydraulic pressure of the lift cylinder to increase in a direction that raises the loading platform so that the height of the loading platform is maintained at a predetermined height.

[0007] This loading platform lifting device can prevent the loading platform from swinging downward when a worker uses the loading platform as a foothold to get on or off a cargo box.

[0008] The loading platform lifting device may include a pressing member disposed above the loading platform in the step use position and overlapping with the loading platform in the step use position as viewed from above. The control executed by the control device may be control to press the loading platform against the pressing member by increasing hydraulic pressure in the lift cylinder when the loading platform is stopped in the step use position.

[0009] According to this configuration, the height of the receiving platform is easily maintained at a predetermined height by pressing the receiving platform against the pressing member.

[0010] The pressing member may be the guide rail. The control device may execute control to press the loading platform against the guide rail when the loading platform is stopped at the step use position.

[0011] According to this configuration, there is no need to separately attach a member to the vehicle body or the like against which the loading platform is pressed.

[0012] The pressing member may be provided with a contact member that comes into contact with the load receiving platform that is pressed against the pressing member. The contact member may be made of a flexible material.

[0013] According to this configuration, when the load receiving table is pressed against the pressing member, the load acting on the load receiving table and the pressing member can be reduced.

[0014] The control device may execute control to reduce the hydraulic pressure of the lift cylinder when the loading platform is moved in the forward / backward direction.

[0015] With this configuration, when the receiving platform is moving in the front-rear direction, the receiving platform is less likely to rub against components located above the receiving platform, thereby reducing wear on the receiving platform.

[0016] The loading platform lifting device may include an operating device that is operated to command the operation of the lift cylinder and the slide cylinder. The control device may execute control to move the loading platform to the step use position and stop the loading platform at the step use position when the operating device is operated in a predetermined operating manner.

[0017] With this configuration, the worker can easily move the loading platform to the step utilization position.

[0018] The operation device may have a power switch for turning the power of the operation device on / off, an up switch for sending a command to the control device to move the loading platform upward or forward, and a down switch for sending a command to the control device to move the loading platform downward or backward. The predetermined operation method may be such that any two or more switches among the power switch, the up switch, and the down switch are operated simultaneously.

[0019] With this configuration, the worker can easily move the loading platform to the step utilization position.

[0020] The operating device may have a power switch for turning the power of the operating device on and off, an up switch for sending a command to the control device to move the loading platform upward or forward, a down switch for sending a command to the control device to move the loading platform downward or backward, and a step utilization switch for sending a command to the control device to move the loading platform to the step utilization position and stop the loading platform at the step utilization position. The predetermined operating method may be to operate the step utilization switch.

[0021] With this configuration, the worker can easily move the loading platform to the step utilization position. [Effects of the Invention]

[0022] According to the present invention, when a worker uses the loading platform as a foothold to get on and off a cargo box, the loading platform can be prevented from swinging downward. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a side view of a vehicle according to an embodiment. [Figure 2] 1 is a plan view of a loading platform lifting device according to an embodiment; [Figure 3] 1 is a side view of a platform lifting device with the platform in a stowed position, according to one embodiment; FIG. [Figure 4] 1 is a side view of a loading platform lifting device with the loading platform in the extended position, according to one embodiment; FIG. [Figure 5] 1 is a side view of a platform lifting device with the platform in a step-access position, according to one embodiment. FIG. [Figure 6] FIG. 2 is a side view of a platform lifting device with the platform deployed, according to one embodiment. [Figure 7] FIG. 2 is a circuit diagram showing an example of a configuration of a hydraulic circuit. [Figure 8] 1 is a block diagram of a platform lifting device according to an embodiment; [Figure 9] FIG. 10 is a side view of a loading platform lifting device according to another embodiment. [Figure 10] FIG. 10 is a block diagram of a loading platform lifting device according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a side view of a vehicle 1 according to one embodiment. In the following description, unless otherwise specified, the terms front, rear, left, right, top, and bottom refer to the front, rear, left, right, top, and bottom as seen from the perspective of a driver seated in a driver's seat (not shown) of the vehicle 1. The symbols F, Rr, L, R, U, and D in the drawings represent the front, rear, left, right, top, and bottom, respectively.

[0025] As shown in FIG. 1, vehicle 1 has a vehicle body 2 and a loading platform lifting device 10. Vehicle body 2 has a chassis frame 3, a driver's cab 4, and a cargo box 5. Chassis frame 3 supports driver's cab 4 and cargo box 5. Although not shown, a driver's seat is provided inside driver's cab 4. The cargo box 5 is located behind driver's cab 4. Loading platform lifting device 10 is provided at the rear of vehicle body 2.

[0026] FIG. 2 is a plan view of the receiving platform lifting device 10. The receiving platform lifting device 10 is a device used when loading and unloading cargo into and from a cargo box 5. As shown in FIG. 2, the receiving platform lifting device 10 includes a guide rail 12, a slider 15, an arm mechanism 20, a receiving platform 25, a lift cylinder 30, a slide cylinder 32, and a hydraulic circuit 40. The receiving platform lifting device 10 of this embodiment is a so-called retractable receiving platform lifting device that is configured so that the receiving platform 25 can be stored below the vehicle body 2.

[0027] FIG. 3 is a side view of the receiving platform lifting device 10 when the receiving platform 25 is in the storage position. FIG. 4 is a side view of the receiving platform lifting device 10 when the receiving platform 25 is in the extended position. FIG. 5 is a side view of the receiving platform lifting device 10 when the receiving platform 25 is in the step-using position. FIGS. 4 and 5 show the receiving platform lifting device 10 in a state where the receiving platform 25 is folded. FIG. 6 is a side view of the receiving platform lifting device 10 when the receiving platform 25 is unfolded. In FIG. 6, the receiving platform lifting device 10 is shown with a solid line when the receiving platform 25 is at box height, and with a two-dot chain line when the receiving platform 25 is at intermediate height and at ground level. Note that FIGS. 3, 4, and 6 show the receiving platform lifting device 10 with the hydraulic circuit 40 and the operating device 80 removed.

[0028] In this specification, the storage position refers to the position of the receiving platform 25 in the front-to-rear direction when the entire receiving platform 25 overlaps with the vehicle body 2 when viewed from above, as shown in FIG. 3. The extended position refers to the position of the receiving platform 25 in the front-to-rear direction when the entire receiving platform 25 does not overlap with the vehicle body 2 when viewed from above, as shown in FIG. 4. When the receiving platform 25 is in the extended position, the receiving platform 25 is located rearward of the vehicle body 2. The step use position refers to a position rearward of the storage position and forward of the extended position, as shown in FIG. 5. When the receiving platform 25 is in the step use position, as shown in FIG. 5, the front part of the receiving platform 25 overlaps with the guide rail 12 when viewed from above, and the rear part of the receiving platform 25 does not overlap with the vehicle body 2 when viewed from above.

[0029] The ground contact height is the vertical position of the cargo receiving platform 25 when it is in contact with the ground, as shown by the two-dot chain line in Figure 6. The cargo box height is the vertical position of the cargo receiving platform 25 when the top surface of the cargo receiving platform 25 is at the same height as the floor surface of the cargo box 5, as shown by the solid line in Figure 6. Note that "the same height" here includes cases where they are exactly the same height and cases where they are approximately the same height. The intermediate height is the vertical position of the cargo receiving platform 25 when it is at a height between the ground contact height and the cargo box height, as shown by the two-dot chain line in Figure 6.

[0030] As shown in FIG. 3, the guide rails 12 are provided at the bottom of the vehicle body 2 and extend in the front-to-rear direction. As shown in FIG. 2, in this embodiment, a pair of left and right guide rails 12 are provided. The pair of left and right guide rails 12 are disposed above the load receiving platform 25 in the storage position and are disposed so as to overlap with the load receiving platform 25 in the storage position when viewed from above. The two guide rails 12 are disposed parallel to the left and right. The two guide rails 12 are disposed at the same position in the front-to-rear and up-to-down directions. The front ends of the two guide rails 12 are connected by a stay 13 extending in the left-to-right direction. As shown in FIG. 3, in this embodiment, the rear ends of the guide rails 12 are disposed forward of the rear end of the vehicle body 2. Therefore, in this embodiment, the guide rails 12 are disposed so that the entire guide rails 12 overlap with the vehicle body 2 when viewed from above.

[0031] The sliders 15 are provided so as to be movable in the front-rear direction along the guide rails 12. In this embodiment, as shown in FIG. 2 , a pair of sliders 15 are provided on the left and right. The left slider 15 engages with the left guide rail 12. The right slider 15 engages with the right guide rail 12. The front ends of the pair of left and right sliders 15 are connected by a connecting member 16 extending in the left-right direction. The configuration of the sliders 15 is not particularly limited. For example, the sliders 15 may be provided so as to slide relative to the guide rails 12. Furthermore, the sliders 15 may have rollers (not shown) that roll on the guide rails 12.

[0032] As shown in Fig. 2, in this embodiment, a pair of arm mechanisms 20 are provided on the left and right sides. The left arm mechanism 20 is rotatably connected to the left slider 15. The right arm mechanism 20 is rotatably connected to the right slider 15. The configuration of the arm mechanisms 20 is not particularly limited. As shown in Fig. 3, in this embodiment, the arm mechanism 20 has a tilt arm 21, a lift arm 22, and a compression arm 23.

[0033] The tilt arm 21 extends in the vertical direction. An upper portion of the tilt arm 21 is rotatably connected to the connecting member 16 via a pin P1. The lift arm 22 extends in the front-to-rear direction. A front end of the lift arm 22 is rotatably connected to the tilt arm 21 via a pin P2 below the pin P1. A rear end of the lift arm 22 is rotatably connected to the load receiving platform 25 via a pin P3. The compression arm 23 is disposed below the lift arm 22. The compression arm 23 extends in the front-to-rear direction. A front end of the compression arm 23 is rotatably connected to the tilt arm 21 via a pin P4. A rear end of the compression arm 23 is rotatably connected to the load receiving platform 25 via a pin P5.

[0034] The receiving platform 25 is a member used as a platform on which cargo is placed during cargo handling operations. The receiving platform 25 is rotatably connected to the tip of the arm mechanism 20. In this embodiment, as described above, the receiving platform 25 is rotatably connected to the rear end of the lift arm 22 by pin P3 and to the rear end of the compression arm 23 by pin P5. The receiving platform 25 has a receiving platform base 26 and a receiving platform main body 27. The receiving platform main body 27 is rotatably connected to the receiving platform base 26 by pin P6. From the unfolded state of the receiving platform 25 shown in FIG. 6, the receiving platform main body 27 can be rotated forward around pin P6 to fold the receiving platform 25 as shown in FIG. 3. As shown in FIG. 6, when the receiving platform 25 is unfolded, the receiving platform main body 27 is located rearward of the receiving platform base 26. As shown in FIG. 3, when the receiving tray 25 is in the folded state, the receiving tray main body 27 is located above the receiving tray base 26.

[0035] The lift cylinder 30 is a device that drives the arm mechanism 20. The lift cylinder 30 is a single-acting hydraulic cylinder. A pair of lift cylinders 30 is provided on the left and right sides. The left lift cylinder 30 is connected to the left arm mechanism 20. The right lift cylinder 30 is connected to the right arm mechanism 20. One end of the lift cylinder 30 is rotatably connected to the tilt arm 21 by a pin P7. The other end of the lift cylinder 30 is rotatably connected to the lift arm 22 by a pin P8. When the lift cylinder 30 rotates the arm mechanism 20, the loading platform 25 rises and falls as shown in Figure 6. When the lift cylinder 30 extends, the loading platform 25 rises. When the lift cylinder 30 retracts, the loading platform 25 descends.

[0036] The slide cylinder 32 is a device that drives the slider 15 in the forward and backward directions. In this embodiment, the slide cylinder 32 is a double-acting hydraulic cylinder. As shown in FIG. 2 , a pair of left and right slide cylinders 32 are provided. In this embodiment, one end of each of the pair of left and right slide cylinders 32 is fixed to the stay 13. The other end of each of the pair of left and right slide cylinders 32 is connected to the connecting member 16. When the slide cylinders 32 are driven, the slider 15 moves forward and backward together with the connecting member 16. When the slide cylinders 32 move the slider 15 forward and backward, the receiving platform 25 moves forward and backward between the stored position shown in FIG. 3 and the extended position shown in FIG. 4. When the slide cylinders 32 are extended, the receiving platform 25 moves backward. When the slide cylinders 32 are retracted, the receiving platform 25 moves forward. When the receiving platform 25 moves between the stored position and the extended position, the receiving platform 25 is at an intermediate height in the vertical direction.

[0037] FIG. 7 is a circuit diagram showing an example of the configuration of the hydraulic circuit 40. The hydraulic circuit 40 is a mechanism for operating the lift cylinder 30 and the slide cylinder 32. As shown in FIG. 2, the hydraulic circuit 40 is disposed to the left of the left arm mechanism 20. The location of the hydraulic circuit 40 is not particularly limited. As shown in FIG. 7, the platform lifting device 10 includes an electric motor 41, a hydraulic pump 42, an oil tank 43, a hydraulic oil supply passage 44, an upward operation control valve 45, a hydraulic oil return passage 46, a downward operation control valve 47, a flow control valve 48, and a main relief valve 49.

[0038] The hydraulic pump 42 is driven by an electric motor 41. An oil tank 43 is provided on the suction side of the hydraulic pump 42. A hydraulic oil supply passage 44 is a passage for supplying hydraulic oil discharged from the hydraulic pump 42 to the lift cylinder 30. A lifting operation control valve 45 is provided to open or close the flow of hydraulic oil in the hydraulic oil supply passage 44. A hydraulic oil return passage 46 branches off from the hydraulic oil supply passage 44 upstream of the lifting operation control valve 45 and is connected to the oil tank 43. A lowering operation control valve 47 is provided to open or close the flow of hydraulic oil in the hydraulic oil return passage 46. A flow control valve 48 is provided downstream of the lowering operation control valve 47. A main relief valve 49 determines the maximum value of the discharge pressure of the hydraulic pump 42.

[0039] For example, when the lifting control valve 45 is open and the lowering control valve 47 is closed, the flow in the hydraulic oil supply passage 44 is open and the flow in the hydraulic oil return passage 46 is blocked. When the hydraulic pump 42 is driven in this state, the hydraulic oil discharged from the hydraulic pump 42 passes through the hydraulic oil supply passage 44 and is supplied to the lift cylinder 30. This causes the lift cylinder 30 to extend, and the loading platform 25 to rise.

[0040] On the other hand, when the lifting control valve 45 and the lowering control valve 47 are both open, the hydraulic oil return passage 46 is open. When the hydraulic pump 42 stops operating in this state, the weight of the platform 25 causes hydraulic oil to be discharged from the lift cylinder 30 and flow through the hydraulic oil return passage 46 to the oil tank 43. This causes the lift cylinder 30 to contract, and the platform 25 to descend.

[0041] The platform lifting device 10 also has a hydraulic oil supply passage 51, a throttle valve 52, a check valve 53, a hydraulic oil supply passage 54, a reverse operation control valve 55, a hydraulic oil return passage 56, a forward operation control valve 57, and a pressure transmitter 58. The hydraulic oil supply passage 51 branches off from the hydraulic pump 42 and is connected to the rod side of the slide cylinder 32. The throttle valve 52 and the check valve 53 are provided in the hydraulic oil supply passage 51. The hydraulic oil supply passage 54 branches off from the hydraulic oil supply passage 51 and is connected to the head side of the slide cylinder 32. The reverse operation control valve 55 is provided to open or close the flow of hydraulic oil in the hydraulic oil supply passage 54. The hydraulic oil return passage 56 branches off from the hydraulic oil supply passage 54 downstream of the reverse operation control valve 55 and is connected to the oil tank 43. The forward operation control valve 57 is provided to open or close the flow of hydraulic oil in the hydraulic oil return passage 56. The pressure transmitter 58 measures the hydraulic pressure value of the hydraulic oil discharged from the hydraulic pump 42 and transmits the hydraulic pressure value to the control device 70, which will be described later.

[0042] For example, when the reverse operation control valve 55 is open and the forward operation control valve 57 is closed, the hydraulic oil supply passages 51 and 54 are connected to each other, and the hydraulic oil return passage 56 is blocked. In this state, the hydraulic oil pressure is equal on the head side and rod side of the slide cylinder 32. Because the head side of the slide cylinder 32 has a larger hydraulic oil pressure-receiving area than the rod side, when the hydraulic oil pressure is equal on the head side and rod side, the slide cylinder 32 extends. Therefore, when the hydraulic pump 42 is driven in this state, the slide cylinder 32 extends, and the load receiving platform 25 moves rearward.

[0043] On the other hand, when the reverse operation control valve 55 is closed and the forward operation control valve 57 is open, the flow through the hydraulic oil return passage 56 is communicated and the flow between the hydraulic oil supply passages 51, 54 is blocked. In this state, when the hydraulic pump 42 is driven, the hydraulic oil discharged from the hydraulic pump 42 is supplied to the rod side of the slide cylinder 32 via the hydraulic oil supply passage 51. Therefore, the hydraulic oil on the head side of the slide cylinder 32 is discharged to the oil tank 43 via the hydraulic oil supply passage 54 and the hydraulic oil return passage 56. This causes the slide cylinder 32 to contract and the load receiving platform 25 to move forward.

[0044] Fig. 8 is a block diagram of the loading platform lifting device 10. As shown in Fig. 8, the loading platform lifting device 10 includes a folding sensor 62, a storage sensor 64, a rear end sensor 66, a height sensor 68, a control device 70, and an operation device 80.

[0045] The folding sensor 62 is a sensor that detects whether the receiving tray 25 is folded or not. The folding sensor 62 is in a detecting state when the receiving tray 25 is in a folded state as shown in Fig. 4, and is in a non-detecting state when the receiving tray 25 is in an unfolded state as shown in Fig. 6. The folding sensor 62 may be, for example, a limit switch attached to the side of the receiving tray 25.

[0046] The storage sensor 64 is a sensor that detects whether the receiving platform 25 is in the storage position. The storage sensor 64 is in a detection state when the receiving platform 25 is in the storage position as shown in FIG. 3. The storage sensor 64 may be, for example, a proximity switch attached to the front of the guide rail 12. The rear end sensor 66 is a sensor that detects whether the receiving platform 25 is in the extended position. The rear end sensor 66 is in a detection state when the receiving platform 25 is in the extended position as shown in FIG. 4. The rear end sensor 66 may be, for example, a proximity switch attached to the rear of the guide rail 12.

[0047] The height sensor 68 is a sensor that measures the height of the loading platform 25. The height sensor 68 may be, for example, an inclination angle sensor attached to the lift arm 22. In this case, the height sensor 68 measures the height of the loading platform 25 by measuring the inclination angle of the lift arm 22. The inclination angle of the lift arm 22 refers to, for example, the angle of the lift arm 22 relative to a horizontal plane.

[0048] The control device 70 controls the operation of the lift cylinder 30 and the slide cylinder 32. The control device 70 is connected to the folding sensor 62, the storage sensor 64, the rear end sensor 66, the height sensor 68, the hydraulic circuit 40, and the operation device 80 via wired or wireless connections, and is communicatively connected to each other. The control device 70 is configured to control the operation of the hydraulic circuit 40 based on signals transmitted from the operation device 80. Specifically, the control device 70 controls the opening and closing of the lifting operation control valve 45, the lowering operation control valve 47, the reverse operation control valve 55, and the forward operation control valve 57 shown in FIG. 7 . The control device 70 controls the operation of the hydraulic circuit 40, thereby controlling the operation of the lift cylinder 30 and the slide cylinder 32. The control device 70 is configured, for example, by a microcomputer having a processor and memory.

[0049] The operating device 80 is a device operated to command the operation of the lift cylinder 30 and the slide cylinder 32. As shown in FIG. 2, the operating device 80 is disposed to the left of the left arm mechanism 20 and in front of the hydraulic circuit 40. The location of the operating device 80 is not particularly limited. The operating device 80 does not have to be mounted on the vehicle body 2, and may be a remote control that can be carried by an operator. As shown in FIG. 8, the operating device 80 has a power switch 81, an up switch 82, and a down switch 83. In this embodiment, the power switch 81, the up switch 82, and the down switch 83 are push-button switches. The operator operates the operating device 80 by pressing these switches as appropriate. The power switch 81 is a switch for turning the power of the operating device 80 on and off.

[0050] The lift switch 82 is a switch for transmitting a command to the control device 70 to move the receiving platform 25 upward or forward. When the lift switch 82 is operated by an operator, the control device 70 moves the receiving platform 25 upward or forward based on the detection states of the folding sensor 62, the storage sensor 64, the rear end sensor 66, and the height sensor 68. For example, when the receiving platform 25 is unfolded and the folding sensor 62 is in a non-detecting state as shown in FIG. 6, the control device 70 moves the receiving platform 25 upward. Also, when the receiving platform 25 is folded and in the extended position as shown in FIG. 4, the folding sensor 62 is in a detecting state and the rear end sensor 66 is in a detecting state. In this case, when the lift switch 82 is operated, the control device 70 moves the receiving platform 25 forward. In this embodiment, the receiving platform 25 moves upward or forward only while the lift switch 82 is pressed.

[0051] The lowering switch 83 is a switch for transmitting a command to the control device 70 to move the receiving platform 25 downward or backward. When the lowering switch 83 is operated by an operator, the control device 70 moves the receiving platform 25 downward or backward based on the detection states of the folding sensor 62, the storage sensor 64, the rear end sensor 66, and the height sensor 68. For example, when the receiving platform 25 is unfolded and the folding sensor 62 is in a non-detecting state as shown in FIG. 6, the control device 70 moves the receiving platform 25 downward. Also, when the receiving platform 25 is folded and in the storage position as shown in FIG. 3, the folding sensor 62 is in a detecting state and the storage sensor 64 is in a detecting state. In this case, when the lowering switch 83 is operated, the control device 70 moves the receiving platform 25 backward. In this embodiment, the receiving platform 25 moves downward or backward only while the lowering switch 83 is pressed.

[0052] The receiving platform 25 described above may also be used as a platform for a worker to get on and off the cargo box 5. When the receiving platform 25 is used as a platform, the worker does not necessarily need to move the receiving platform 25 from the stored position to the extended position. For example, the receiving platform 25 may be stopped at the step use position as shown in FIG. 5 . Therefore, in the receiving platform lifting device 10 according to this embodiment, when the operating device 80 is operated in a predetermined manner, the control device 70 executes control to move the receiving platform 25 from the stored position to the step use position and stop the receiving platform 25 at the step use position. In this embodiment, when the power switch 81 and the lowering switch 83 are operated simultaneously, the control device 70 executes control to move the receiving platform 25 to the step use position and stop it.

[0053] The operation of the receiving platform lifting / lowering device 10 according to this embodiment will be described below. Here, the operation of the receiving platform lifting / lowering device 10 when the receiving platform 25 in the storage position is pulled out rearward and a package is placed on the package box 5 will be described as an example.

[0054] As shown in FIG. 3, when the loading platform 25 is in the storage position, the slide cylinder 32 is contracted and the storage sensor 64 is in a detection state. In this state, if the lowering switch 83 is operated, a command to move the loading platform 25 rearward is sent to the control device 70. Based on this command, the control device 70 controls the hydraulic circuit 40 to extend the slide cylinder 32. Specifically, the control device 70 drives the hydraulic pump 42, opens the reverse operation control valve 55, and closes the forward operation control valve 57. This causes the loading platform 25 to move rearward. In addition, when moving the loading platform 25 rearward, the control device 70 discharges hydraulic oil from the lift cylinder 30 and reduces the hydraulic pressure of the lift cylinder 30. In this embodiment, the control device 70 stops the hydraulic pump 42 and opens the lifting control valve 45 and the lowering control valve 47 for a predetermined time to reduce the hydraulic pressure in the lift cylinder 30 to a predetermined pressure, and then moves the loading platform 25 rearward. Whether the hydraulic pressure in the lift cylinder 30 is at the predetermined pressure may be determined, for example, based on the measurement value of the pressure transmitter 58 provided in the hydraulic circuit 40. When the loading platform 25 moves to the extended position, the rear end sensor 66 enters a detection state. When the rear end sensor 66 enters a detection state, the control device 70 closes the reverse control valve 55 and stops the supply of hydraulic oil to the slide cylinder 32. This stops the loading platform 25 at the extended position.

[0055] As shown in Figure 4, when the lowering switch 83 is further operated while the loading platform 25 is in the extended position, a command to move the loading platform 25 downward is sent to the control device 70. Based on this command, the control device 70 controls the hydraulic circuit 40 to contract the lift cylinder 30. Specifically, the control device 70 stops the operation of the hydraulic pump 42 and opens the lifting operation control valve 45 and the lowering operation control valve 47. This causes the loading platform 25 to move downward.

[0056] As shown by the two-dot chain line in Figure 6, when the receiving platform 25 is stopped at ground level, by rotating the receiving platform main body 27 around pin P6, the receiving platform 25 is unfolded. By unfolding the receiving platform 25, the worker can place a load on the receiving platform 25.

[0057] When the lift switch 82 is operated while the loading platform 25 is deployed and at ground level, a command to move the loading platform 25 upward is sent to the control device 70. Based on this command, the control device 70 controls the hydraulic circuit 40 to extend the lift cylinder 30. Specifically, the control device 70 drives the hydraulic pump 42, opens the lift control valve 45, and closes the lowering control valve 47. This causes the loading platform 25 to move upward. When the height sensor 68 detects that the loading platform 25 has moved to the cargo box height, the control device 70 stops driving the hydraulic pump 42 and closes the lift control valve 45. This stops the supply of hydraulic oil to the lift cylinder 30, and the loading platform 25 stops at the cargo box height. When the loading platform 25 is at the cargo box height, the top surface of the loading platform 25 and the floor of the cargo box 5 are at the same height, making it easy for workers to move cargo from the loading platform 25 to the cargo box 5.

[0058] As described above, in the receiving platform lifting device 10 of this embodiment, the receiving platform 25 can be stopped at the step use position and used as a foothold for workers to get on and off the cargo box 5. The operation of the receiving platform lifting device 10 when the receiving platform 25 is used as a foothold will be described below.

[0059] When the power switch 81 and the lowering switch 83 are operated simultaneously while the loading platform 25 is in the storage position as shown in FIG. 3, a command to move the loading platform 25 backward to the step use position and stop it at the step use position is sent to the control device 70. Based on this command, the control device 70 extends the slide cylinder 32 and moves the loading platform 25 backward from the storage position. When the loading platform 25 moves to the step use position, the control device 70 stops the supply of hydraulic oil to the slide cylinder 32 and stops the movement of the loading platform 25. In addition, the control device 70 executes control to reduce the hydraulic pressure of the lift cylinder 30 when moving the loading platform 25 backward, just as when moving the loading platform 25 from the storage position to the extended position.

[0060] The method for detecting whether the receiving platform 25 has reached the step use position is not particularly limited. For example, a position sensor may be provided on the guide rail 12 or the like to detect whether the receiving platform 25 has reached the step use position. This position sensor may be, for example, a proximity switch. Alternatively, whether the receiving platform 25 has reached the step use position may be detected based on the elapsed time since the receiving platform 25 started moving.

[0061] Incidentally, when a worker uses the cargo receiving platform 25 as a foothold to get on or off the cargo box 5, the weight of the worker may cause the cargo receiving platform 25 to swing downward. In particular, in this embodiment, when the cargo receiving platform 25 is moved to the step use position, the hydraulic pressure of the lift cylinder 30 is reduced. In this manner, if a worker stands on the cargo receiving platform 25 while the hydraulic pressure of the lift cylinder 30 is reduced, the cargo receiving platform 25 is likely to swing downward.

[0062] Therefore, in this embodiment, when the loading platform 25 is stopped at the step use position, the control device 70 executes control to increase the hydraulic pressure of the lift cylinder 30 in a direction to raise the loading platform 25 so that the height of the loading platform 25 is maintained at a predetermined height. More specifically, in this embodiment, when the loading platform 25 is stopped at the step use position, the control device 70 executes control to press the loading platform 25 against the guide rail 12. At this time, the control device 70 closes the lowering control valve 47 and opens the raising control valve 45, and drives the hydraulic pump 42 to increase the hydraulic pressure of the lift cylinder 30 to a predetermined pressure. For example, the hydraulic pressure of the lift cylinder 30 when the loading platform 25 is moved to the step use position (in other words, before the loading platform 25 is pressed against the guide rail 12) is defined as P. The control device 70 increases the hydraulic pressure of the lift cylinder 30 from P to P + ΔP by increasing the hydraulic pressure by ΔP. As a result, the control device 70 presses the loading platform 25 against the guide rail 12. When the hydraulic pressure of the lift cylinder 30 reaches a predetermined pressure, the control device 70 closes the lifting operation control valve 45 and stops the supply of hydraulic oil to the lift cylinder 30. Whether the hydraulic pressure value of the lift cylinder 30 is the predetermined pressure may be determined based on the measurement value of the pressure transmitter 58 provided in the hydraulic circuit 40, for example.

[0063] The receiving platform lifting device 10 according to this embodiment includes a lift cylinder 30 that raises and lowers the receiving platform 25, a slide cylinder 32 that moves the receiving platform 25 in the forward and backward directions, and a control device 70 that controls the operation of the lift cylinder 30 and the slide cylinder 32. When the receiving platform 25 is stopped at the step use position, the control device 70 executes control to increase the hydraulic pressure of the lift cylinder 30 in a direction that raises the receiving platform 25 so that the height of the receiving platform 25 is maintained at a predetermined height. As a result, when the receiving platform 25 is stopped at the step use position, the hydraulic pressure of the lift cylinder 30 is increased in a direction that raises the receiving platform 25, and therefore, when a worker stands on the receiving platform 25, downward swinging of the receiving platform 25 can be suppressed.

[0064] According to this embodiment, when the receiving platform 25 is stopped at the step use position, the control device 70 executes control to press the receiving platform 25 against the guide rail 12. This makes it easier to maintain the height of the receiving platform 25 at a set height. In addition, when a worker stands on the receiving platform 25, the receiving platform 25 is less likely to rattle.

[0065] According to this embodiment, when the loading platform 25 is moved in the forward / backward direction, the control device 70 executes control to reduce the hydraulic pressure of the lift cylinder 30. This makes it less likely that the loading platform 25 and the guide rail 12 will rub against each other when the loading platform 25 moves in the forward / backward direction, thereby suppressing wear on the loading platform 25 and the guide rail 12.

[0066] According to this embodiment, the receiving platform lifting device 10 is equipped with an operating device 80 that is operated to command the operation of the lift cylinder 30 and the slide cylinder 32. The operating device 80 has a power switch 81, an up switch 82, and a down switch 83. When the power switch 81 and the down switch 83 are operated simultaneously, the control device 70 executes control to move the receiving platform 25 to the step use position and stop the receiving platform 25 at the step use position. This allows the worker to easily move the receiving platform 25 to the step use position.

[0067] Although one embodiment of the present invention has been described above, the embodiment is merely an example, and various other embodiments are possible for the present invention.

[0068] FIG. 9 is a side view of a receiving platform lifting device 10 according to another embodiment. FIG. 9 illustrates the receiving platform lifting device 10 when the receiving platform 25 is in the extended position. As shown in FIG. 9, a contact member 14 may be attached to the guide rail 12 so as to come into contact with the receiving platform 25 when control is executed to press the receiving platform 25 against the guide rail 12. The receiving platform 25 may be indirectly pressed against the guide rail 12 via the contact member 14. The material and shape of the contact member 14 are not particularly limited. The contact member 14 may be made of a flexible material, such as various rubber materials or a sponge-like material. The contact member 14 may be configured to deform to absorb a portion of the force applied from the receiving platform 25 to the guide rail 12. This reduces the load on the guide rail 12 and the receiving platform 25 when the receiving platform 25 is pressed against the guide rail 12. Alternatively, the contact member 14 may be a metal roller.

[0069] In the above embodiment, when the loading platform 25 is stopped at the step use position, the loading platform 25 is pressed against the guide rail 12, but the pressing member against which the loading platform 25 is pressed is not limited to this. For example, the loading platform lifting device 10 may be configured so that the loading platform 25 is pressed against the vehicle body 2. A part that the vehicle 1 has traditionally had may also be used as the pressing member. Furthermore, the pressing member may be a dedicated member separately attached to the vehicle body 2, the guide rail 12, or the like.

[0070] In the above embodiment, when the power switch 81 and the lowering switch 83 are operated simultaneously, the control device 70 is configured to execute control to move the receiving platform 25 to the step-using position and stop it. However, the control device 70 may be configured to execute similar control when the power switch 81 and the up switch 82 are operated simultaneously. The control device 70 may also be configured to execute similar control when the up switch 82 and the down switch 83 are operated simultaneously, or when the three switches, the power switch 81, the up switch 82, and the down switch 83, are operated simultaneously. Therefore, the control device 70 may be configured to execute control to move the receiving platform 25 to the step-using position and stop it when any two or more switches among the power switch 81, the up switch 82, and the down switch 83 are operated simultaneously.

[0071] 10 is a block diagram of the receiving platform lifting device 10 according to another embodiment. The operating device 80 may have a step use switch 84 in addition to the above three switches. In this case, the control device 70 may be configured to execute control to move the receiving platform 25 to the step use position and stop the receiving platform 25 at the step use position when the step use switch 84 is operated. There are no limitations on the type of step use switch 84, and it may be, for example, a push button switch.

[0072] In the above embodiment, the loading platform 25 is stopped at the step utilization position when used as a foothold for a worker. However, when the loading platform 25 is used as a foothold for a worker, the loading platform 25 does not necessarily have to be stopped at the step utilization position and may be moved to the extended position. In other words, the loading platform 25 may be used as a foothold while stopped at the extended position. Even in this case, if a worker stands on the loading platform 25, there is a risk that the loading platform 25 will swing downward. Therefore, the control device 70 may be configured to execute control to increase the hydraulic pressure of the lift cylinder 30 in a direction to raise the loading platform 25 so that the height of the loading platform 25 is maintained at a predetermined height, even when the loading platform 25 is stopped at the extended position.

[0073] Unless otherwise specified, the embodiments do not limit the present invention. Furthermore, the embodiments of the invention disclosed herein can be modified in various ways. Unless any particular problem arises, the components and processes described herein can be omitted or combined as appropriate. [Explanation of symbols]

[0074] 1 vehicle 2. Body 10 Loading platform lifting device 12 Guide rail 14 Contact member 15 Slider 20 Arm mechanism 25 Loading platform 30 Lift cylinder 32 Slide cylinder 70 Control device 80 Operating device 81 Power switch 82 Up switch 83 Down switch 84 Step Use Switch

Claims

1. a guide rail provided at the bottom of the vehicle body and extending in the front-rear direction; a slider provided movably along the guide rail; an arm mechanism rotatably connected to the slider; a load receiving platform rotatably connected to the tip of the arm mechanism; a lift cylinder that raises and lowers the loading platform by rotating the arm mechanism; a slide cylinder that moves the slider in the front-rear direction to move the loading platform in the front-rear direction between a storage position where the loading platform is entirely overlapped with the vehicle body when viewed from above, and a drawn-out position where the loading platform is entirely not overlapped with the vehicle body when viewed from above; a control device for controlling the operation of the lift cylinder and the slide cylinder, The lift cylinder is a hydraulic cylinder, The control device A loading platform lifting device that controls the hydraulic pressure of the lift cylinder to raise the loading platform so that the height of the loading platform is maintained at a predetermined height when the loading platform is stopped at the pulled-out position or at a step-use position where no part of the loading platform overlaps with the vehicle body when viewed from above.

2. a pressing member disposed above the load receiving platform at the step use position and arranged so as to overlap the load receiving platform at the step use position when viewed from above; 2. The loading platform lifting device according to claim 1, wherein the control executed by the control device is a control for pressing the loading platform against the pressing member by increasing hydraulic pressure in the lift cylinder when the loading platform is stopped at the step utilization position.

3. the pressing member is the guide rail, The control device The loading platform lifting device according to claim 2, wherein when the loading platform is stopped at the step using position, control is executed to press the loading platform against the guide rail.

4. A contact member is attached to the pressing member and contacts the load receiving platform pressed against the pressing member, 3. The load-receiving platform lifting device according to claim 2, wherein the contact member is made of a flexible material.

5. The control device 2. The loading platform lifting device according to claim 1, wherein control is executed to reduce the hydraulic pressure of the lift cylinder when the loading platform is moved forward or backward.

6. an operating device that is operated to command the operation of the lift cylinder and the slide cylinder; The control device The loading platform lifting device according to claim 1, wherein when the operating device is operated in a predetermined manner, the loading platform is moved to the step utilization position and controlled to stop the loading platform at the step utilization position.

7. The operating device is a power switch for turning on / off the power of the operating device; a lift switch for sending a command to the controller to move the platter up or forward; a lowering switch for sending a command to the controller to move the loading platform downward or backward; The predetermined operation method includes:

7. The loading platform lifting device according to claim 6, wherein any two or more of the power switch, the up switch, and the down switch are operated simultaneously.

8. The operating device is a power switch for turning on / off the power of the operating device; a lift switch for sending a command to the controller to move the platter up or forward; a down switch for sending a command to the controller to move the platter down or backward; a step utilization switch for transmitting a command to the control device to move the loading platform to the step utilization position and stop the loading platform at the step utilization position; The predetermined operation method includes:

7. The loading platform lifting device according to claim 6, wherein the step utilization switch is operated.

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