Loading platform lifting device

Abstract

To provide a loading table lifting device which enables a loading table to be stowed into an underfloor space while including a function for tilting the loading table.SOLUTION: A loading table lifting device includes: guide rails attached to a lower part of a vehicle frame; a slider which may move forward and rearward along the guide rails; arms rotatably connected to the slider; and a loading table which is rotatably connected to tips of the arms. The loading table lifting device determines whether the loading table is in a folded state and determines whether a relative angle of the loading table relative to the guide rails is within a set angle range. The loading table lifting device can draw the loading table into the lower part of the vehicle frame in response to a storage operation on condition that the loading table is in the folded state and the relative angle of the loading table is in the set angle range.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a loading platform lifting device that assists in loading and unloading of luggage and the like onto and from the loading platform of a vehicle. [Background technology]

[0002] A loading platform lifting device is a device that raises and lowers the loading platform between the height of the vehicle's loading platform floor and the ground, and supports the loading and unloading of cargo and other items from the loading platform. Some loading platform lifting devices are of an underfloor storage type that retracts the loading platform under the vehicle frame and stores it (Patent Document 1). There are also loading platform lifting devices that stand up along the rear surface of the loading platform and store it while the vehicle is traveling, etc. (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-123778 [Patent Document 2] Japanese Patent Publication No. 2020-121632 Summary of the Invention [Problem to be solved by the invention]

[0004] The receiving platform lifting device described in Patent Document 2 can tilt the receiving platform to adjust its angle, which has the advantage of making it possible to adjust the tilt angle, for example, when the receiving platform tilts due to the weight of the loaded cargo. Although the underfloor storage type receiving platform lifting device described in Patent Document 1 does not have such a receiving platform tilt function, it is possible to add a receiving platform tilt function by applying the configuration of the receiving platform lifting device described in Patent Document 2. However, with an underfloor storage type receiving platform lifting device, it is desirable for the receiving platform to be retracted at a specified angle relative to the vehicle frame, and adding a loading platform tilt function can result in variations in the receiving platform angle.

[0005] In underfloor storage platform lifting devices, the platform must be as close as possible to the vehicle frame during storage to ensure a predetermined departure angle. Therefore, if the platform is tilted relative to the vehicle frame, the platform may interfere with surrounding structures when being moved under or removed from the frame, or the predetermined departure angle may not be maintained when the platform is stored. Furthermore, a configuration is sometimes adopted in which the platform is locked with a fall prevention member during storage to prevent the platform from descending due to hydraulic oil leakage from the lift cylinder. However, if the platform is tilted, the platform may not be properly locked by the fall prevention member.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a loading platform lifting device that has a tilt function for the loading platform and can properly store the loading platform under the floor. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a vehicle comprising a guide rail attached to the bottom of a vehicle frame, a slider movable back and forth along the guide rail, an arm rotatably connected to the slider, a load receiving platform rotatably connected to the tip of the arm, a lift cylinder that rotates the arm to raise and lower the load receiving platform, a slide cylinder that moves the load receiving platform back and forth together with the slider, a tilt cylinder that tilts the load receiving platform, a gate sensor that detects whether the load receiving platform is in a folded state, a tilt sensor that detects a state quantity related to the relative angle of the load receiving platform with respect to the guide rail, and an operating device for storing the load receiving platform. and a control device that drives the lift cylinder and the tilt cylinder in accordance with a signal from the operating device and raises, lowers, and tilts the loading platform, wherein the control device determines whether the loading platform is in a folded state based on the output of the gate sensor, determines whether the relative angle of the loading platform is within a set angle range based on the output of the tilt sensor, and, provided that the loading platform is in a folded state and the relative angle of the loading platform is within the set angle range, contracts the slide cylinder in accordance with a storage operation signal input from the operating device in conjunction with a storage operation, thereby enabling the loading platform to be retracted under the vehicle frame. [Effects of the Invention]

[0008] According to the present invention, the loading platform can be properly stored under the floor while being provided with a tilt function. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a left side view showing the overall structure of a vehicle equipped with a loading platform lifting device according to a first embodiment of the present invention. [Figure 2] 1 is a right side view of a loading platform lifting device according to a first embodiment of the present invention; [Figure 3] 1 is an enlarged view of the vicinity of the base of the arm of the loading platform lifting device according to the first embodiment of the present invention; [Figure 4] Plan view of the part shown in Figure 3 [Figure 5]FIG. 1 is a hydraulic circuit diagram showing an example of the configuration of a power unit provided in a loading platform lifting device according to a first embodiment of the present invention. [Figure 6] 1 is a diagram showing the installation of a tilt sensor in a loading platform lifting device according to a first embodiment of the present invention; [Figure 7] Cross-sectional view taken along line VII-VII in Figure 4 [Figure 8] 1 is an explanatory diagram of the operation of the loading platform by the lift cylinder of the loading platform lifting device according to the first embodiment of the present invention; [Figure 9] 1 is an explanatory diagram of the operation of the loading platform by the tilt cylinder of the loading platform lifting device according to the first embodiment of the present invention; [Figure 10] 1 is an explanatory diagram of the operation of unfolding the receiving platform of the receiving platform lifting device according to the first embodiment of the present invention; [Figure 11] 1 is a flowchart showing a control procedure for starting the retraction of the loading platform by a control device provided in the loading platform lifting device according to the first embodiment of the present invention. [Figure 12] 10 is a flowchart showing a control procedure for starting the retraction of the loading platform by a control device provided in the loading platform lifting device according to the second embodiment of the present invention. [Figure 13] 10 is a flowchart showing a control procedure for starting the retraction of the loading platform by a control device provided in the loading platform lifting device according to the third embodiment of the present invention. [Figure 14] FIG. 10 is a hydraulic circuit diagram showing an example of the configuration of a power unit provided in a loading platform lifting device according to a fourth embodiment of the present invention. [Figure 15] 10 is a flowchart showing a control procedure for starting the retraction of the loading platform by a control device provided in the loading platform lifting device according to the fourth embodiment of the present invention. [Figure 16] 10 is a flowchart showing a control procedure for starting the retraction of the loading platform by a control device provided in the loading platform lifting device according to the fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] First Embodiment -vehicle- 1 is a left side view showing the overall structure of a vehicle equipped with a platform lifting device 4 according to a first embodiment of the present invention. In this specification, the left and right sides of FIG. 1 correspond to the front and rear of the platform lifting device 4.

[0012] The vehicle shown in Fig. 1 is configured to include a chassis 1, a driver's cab 2 provided at the front of the chassis 1, a loading platform 3 mounted on the chassis 1, and an underfloor-storable loading platform lifting device 4 provided at the lower rear of the chassis 1. When not in use, such as when the vehicle is being driven, the loading platform 5 of this loading platform lifting device 4 is folded and stored under the chassis 1. When in use, the loading platform 5 is pulled rearward from under the chassis 1 and unfolded, and is raised and lowered between the height of the floor of the loading platform 3 and the height of the ground to assist in loading and unloading of cargo onto and from the loading platform 3.

[0013] -Load receiving platform lifting device- Fig. 2 is a right side view of the loading platform lifting device 4, showing the loading platform 5 in a retracted state. Fig. 3 is an enlarged view of the vicinity of the base of the arm of the loading platform lifting device 4 shown in Fig. 2, and Fig. 4 is a plan view of the part shown in Fig. 3. The guide roller 13 and its support 17 are omitted from Fig. 3.

[0014] As shown in these figures, the receiving platform lifting device 4 is configured to include the receiving platform 5 on which cargo is loaded, as well as a slide unit 10, a lift unit 20, a power unit 30 (Figure 5), an operation device 40 (Figure 5), and a control device 50 (Figure 5). The slide unit 10 is a unit that slides the receiving platform 5 back and forth. The lift unit 20 is a unit that raises, lowers, tilts, and tilts the receiving platform 5. The power unit 30 is a unit that drives the slide unit 10 and the lift unit 20. The operation device 40 is a device that operates to raise, lower, tilt forward, and tilt backward the receiving platform 5. The control device 50 is a device (e.g., a computer) that controls the power unit 30. These elements will be explained in order.

[0015] -Slide unit- The slide unit 10 is composed of left and right guide rails 11, a slider 12, guide rollers 13, left and right slide cylinders 14, etc. The left and right guide rails 11 are attached to the lower rear portion of the vehicle frame 1 so as to extend forward and backward. The slider 12 is composed of left and right blocks 15 and a cross member 16. The left and right blocks 15 are supported by the left and right guide rails 11 and can move forward and backward along the guide rails 11. The cross member 16 extends left and right to connect the left and right blocks 15. The guide roller 13 is rotatably supported at the tip (rear end) of a cantilever-shaped support 17 that is supported by the slider 12 and protrudes rearward. The guide roller 13 is supported with its rotation axis extended left and right, and supports the load receiving platform 5, which tilts when storing and deploying, and guides its movement. The left and right slide cylinders 14 are double-acting hydraulic cylinders that move the slider 12 back and forth, and both ends are connected to the guide rails 11 and the slider 12 via appropriate support members. When the slider 12 moves, the loading platform 5 moves back and forth along the guide rails 11 together with the slider 12.

[0016] -Lift unit- The lift unit 20 is configured to include a left and right pair of a link 21, an arm (lift arm) 22, a tilt cylinder (compression arm) 23, and a lift cylinder 24. The link 21 is connected to the slider 12 (cross member 16) via a bracket 25, and its upper portion is connected to the bracket 25 via a rotating shaft, and its lower portion is rotatable back and forth. The front end of the arm 22 is connected to the link 21 via a rotating shaft and to the slider 12 via the link 21, and the arm 22 is rotatable up and down relative to the slider 12. The receiving platform 5 is rotatably connected to the rear end of the arm 22. The tilt cylinder 23 is a cylinder that tilts the receiving platform 5, and its front end is rotatably connected to the slider 12 (cross member 16) via a bracket 26. The receiving platform 5 is rotatably connected to the rear end of the tilt cylinder 23. The lift cylinder 24 is a cylinder that raises and lowers the loading platform 5, and its front end is rotatably connected to the link 21, which in turn connects it to the slider 12. The rear end of the lift cylinder 24 is rotatably connected to the arm 22. The tilt cylinder 23, when set to a predetermined length, functions as a parallel link together with the arm 22, and the extension and contraction of the lift cylinder 24 raises and lowers the loading platform 5 while maintaining it in a horizontal position relative to the slider 12. The lift cylinder 24 and tilt cylinder 23 may be double-acting, but in this embodiment, single-acting hydraulic cylinders are used.

[0017] -Loading platform- The receiving platform 5 is a foldable lifting platform and includes a base receiving platform 6 and a tip receiving platform 7. The base receiving platform 6 is supported on the rear end of the arm 22 and tilt cylinder 23 of the lift unit 20. The tip receiving platform 7 is connected to the base receiving platform 6 via a hinge 8. Both ends of the hinge 8 are rotatably connected to the base receiving platform 6 and the tip receiving platform 7 via pins (not shown). As such, the rotational movement of the tip receiving platform 7 relative to the base receiving platform 6 has two degrees of freedom, so that the receiving platform 5 can be folded into a position where the receiving surface of the tip receiving platform 7 faces parallel to the upward-facing receiving surface of the base receiving platform 6. In this embodiment, a configuration in which the receiving platform 5 folds in only one place is exemplified, but a folding structure in which it folds in two places may also be used.

[0018] -Power unit- 5 is a hydraulic circuit diagram showing one configuration example of the power unit 30. The power unit 30 shown in this figure includes a hydraulic circuit that drives the slide unit 10 and the lift unit 20, specifically the slide cylinder 14, the tilt cylinder 23, and the lift cylinder 24. The power unit 30 includes an electric motor 31, a hydraulic pump 32, a control valve 33 for the slide cylinder, a control valve 34 for the tilt cylinder, and a control valve 35 for the lift cylinder.

[0019] The electric motor 31 is driven by a battery 57 (not shown). The hydraulic pump 32 is driven by the electric motor 31 and discharges hydraulic oil drawn from a hydraulic oil tank 36. The maximum pressure in the discharge line of the hydraulic pump 32 is limited by a main relief valve 37.

[0020] The control valve 33 is a solenoid valve that controls the flow of hydraulic oil to the slide cylinder 14, switches the connection destination of the hydraulic pump 32 to the bottom-side oil chamber or the rod-side oil chamber of the slide cylinder 14, and holds the slide cylinder 14. The control valve 33 can be configured with multiple two-position switching valves (on / off valves) or a single three-position switching valve (directional control valve). This control valve 33 is driven when a solenoid is excited by a command signal from the control device 50. For example, when the control valve 33 is driven and the hydraulic pump 32 connects to the bottom-side oil chamber of the slide cylinder 14, hydraulic oil is supplied to the bottom-side oil chamber and the slide cylinder 14 extends. Hydraulic oil pushed out from the rod-side oil chamber of the slide cylinder 14 returns to the hydraulic oil tank 36 via the control valve 33. Conversely, when the control valve 33 is driven and the hydraulic pump 32 connects to the rod-side oil chamber of the slide cylinder 14, hydraulic oil is supplied to the rod-side oil chamber and the slide cylinder 14 retracts. The hydraulic oil pushed out from the bottom-side oil chamber of the slide cylinder 14 returns to the hydraulic oil tank 36 via the control valve 33. When no command signal is output from the control device 50 to the control valve 33, the control valve 33 is biased to the closed position by a spring force, closing the bottom-side oil chamber and rod-side oil chamber of the slide cylinder 14 and holding the slide cylinder 14.

[0021] The control valve 34 is a solenoid valve that controls the flow of hydraulic oil to the tilt cylinder 23, switching whether the oil chamber of the tilt cylinder 23 is connected to the hydraulic pump 32 or the hydraulic oil tank 36, and holding the tilt cylinder 23. The control valve 34 can be configured with multiple two-position switching valves (on / off valves), or a single three-position switching valve (directional control valve). This control valve 34 is driven when a solenoid is excited by a command signal from the control device 50. For example, when the control valve 34 is driven and the oil chamber of the tilt cylinder 23 is connected to the hydraulic pump 32, hydraulic oil is supplied to the oil chamber and the tilt cylinder 23 extends. Conversely, when the control valve 34 is driven and the oil chamber of the tilt cylinder 23 is connected to the hydraulic oil tank 36, the weight of the loading platform 5 causes the tilt cylinder 23 to contract, and hydraulic oil pushed out of the oil chamber returns to the hydraulic oil tank 36 via the control valve 34. A flow control valve 38 is provided in the pipe connecting the control valve 34 and the hydraulic oil tank 36, and the speed at which the tilt cylinder 23 retracts is adjusted according to the weight of the loading platform 5. When no command signal is output from the control device 50 to the control valve 34, the control valve 34 is biased to the closed position by a spring force, closing the oil chamber of the tilt cylinder 23 and holding the tilt cylinder 23 in place.

[0022] The control valve 35 is a solenoid valve that controls the flow of hydraulic oil to the lift cylinder 24, switching the connection of the oil chamber of the lift cylinder 24 to the hydraulic pump 32 or the hydraulic oil tank 36, and holding the lift cylinder 24. The control valve 35 can be configured as multiple two-position switching valves (on / off valves) or a single three-position switching valve (directional control valve). This control valve 35 is driven by energizing a solenoid in response to a command signal from the control device 50. For example, when the control valve 35 is driven and the oil chamber of the lift cylinder 24 is connected to the hydraulic pump 32, hydraulic oil is supplied to the oil chamber and the lift cylinder 24 extends. Conversely, when the control valve 35 is driven and the oil chamber of the lift cylinder 24 is connected to the hydraulic oil tank 36, the weight of the loading platform 5 causes the lift cylinder 24 to contract, and hydraulic oil pushed out of the oil chamber returns to the hydraulic oil tank 36 via the control valve 35. A flow control valve 39 is provided in the pipe connecting the control valve 35 and the hydraulic oil tank 36, and adjusts the speed at which the lift cylinder 24 contracts depending on the weight of the loading platform 5. When no command signal is output from the control device 50 to the control valve 35, the control valve 35 is biased to the closed position by a spring force, closing the oil chamber of the lift cylinder 24 and holding the lift cylinder 24.

[0023] -Operation device- The operating device 40 is a remote control that allows the operator to raise, lower, tilt forward, and tilt backward the loading platform 5. The loading platform lifting device 4 is equipped with at least one of a wired remote control and a wireless remote control as the operating device 40. The raising operation is an operation of extending the lift cylinder 24 to raise the loading platform 5, which also doubles as an operation (storing operation) of storing the loading platform 5 by adding contraction of the slide cylinder 14 under predetermined conditions. The lowering operation is an operation of contracting the lift cylinder 24 to lower the loading platform 5, which also doubles as an operation (deployment operation) of deploying the loading platform 5 by adding extension of the slide cylinder 14 under predetermined conditions. The forward tilting operation is an operation of extending the tilt cylinder 23 to tilt the loading platform 5 forward (tilting the rear end of the loading platform 5 in the direction of rising). The rearward tilting operation is an operation of contracting the tilt cylinder 23 to tilt the loading platform 5 rearward (tilting the rear end of the loading platform 5 in the downward direction). The switch of the operating device 40 for performing these operations is a momentary switch, and an operating signal is output from the operating device 40 only during operation, and the output of the operating signal stops when the switch is released. However, an alternate switch may also be used as the switch of the operating device 40.

[0024] -Control device- The control device 50 is, for example, a microcomputer, and has the function of driving the lift cylinder 24 and tilt cylinder 23 in accordance with signals from the operation device 40 to raise, lower, and tilt the loading platform 5. The control device 50 may also have the function of switching and controlling the lift cylinder 24 and slide cylinder 14 under predetermined conditions to execute the unfolding and stowing operations of the loading platform 5. The control device 50 is connected to the battery of the loading platform lifting device 4 via a power switch, and the power to the control device 50 is turned on and off by the power switch.

[0025] Although not shown, the control device 50 includes an input port, memory (RAM, ROM, and other storage devices), a calculation device (CPU), and an output port. The input port receives operation signals from the operating device 40 as well as detection signals from various sensors (rear end sensor a, storage sensor b, gate sensor c, pressure sensor d, tilt sensor e, and tilt sensors f1 and f2, which will be described later). The memory stores various data, such as a control program for the platform lifting device 4 and control thresholds. The calculation device executes processing according to the program stored in the memory and generates command signals to instruct the extension and retraction operations of the lift cylinder 24, tilt cylinder 23, and slide cylinder 14 based on the operation signals and sensor outputs. The command signals generated by the calculation device are output via the output port to the power unit 30, specifically, to the control valves 33-35 and the electric motor 31, as appropriate.

[0026] The control device 50 also has a function of issuing a command to the notification output device A to perform a notification output operation (such as issuing an alarm) via an output port in a predetermined situation. In this case, the notification output device A may be provided in the loading platform lifting device 4 (for example, the operation device 40), or the control device 50 may be electrically connected to the notification output device A provided on the vehicle side, and the control device 50 may issue a command to the on-board notification output device A to perform a notification output operation. The notification output device A may be an audio output device such as a buzzer or speaker, or a display output device such as a lamp or monitor.

[0027] -Sensor- 5, the loading platform lifting device 4 is equipped with a rear end sensor a, a storage sensor b, a gate sensor c, a pressure sensor d, an inclination sensor e, and tilt sensors f1 and f2. These sensors are electrically connected to the control device 50 via cables.

[0028] Rear end sensor In this embodiment, front and rear stoppers (only the rear stopper 18 is shown in FIG. 2 ) that restrict the front and rear movement range of the slider 12 are provided on the guide rail 11. The end of the movement range of the slider 12 in the pull-out direction is limited by the stopper 18. The rear end sensor a is a sensor that detects whether the load receiving platform 5 is near the rear end position (the position where the slider 12 contacts the stopper 18), specifically, whether the distance between the stopper 18 and the slider 12 (the abutment portion 76 with the stopper 18) is equal to or less than a set distance L (e.g., approximately 50 mm). In this example, the rear end sensor a is a proximity switch provided on the slider 12, which turns on when it detects a rear dog (not shown) attached to the guide rail 11 and turns off when it does not detect the rear dog. The rear dog is attached, for example, to the rear of the guide rail 11. The front end of the rear dog is located forward by the set distance L from the position of the rear end sensor a when the slider 12 is at the rear end position. The set distance L can be set, for example, by the positioning of the rear end sensor a and the rear dog, and can also be set to 0 mm. The rear dog extends rearward from its front end and covers the position of the rear end sensor a when the slider 12 is at the rear end position. This allows the rear end sensor a to detect that the load receiving platform 5 is located within the set distance L from the rear end position.

[0029] Storage sensor The storage sensor b is a sensor that detects that the load receiving platform 5 is near the front end position (the position where the slider 12 contacts the front stopper), specifically, that the load receiving platform 5 is located within a predetermined distance (e.g., approximately 100 mm) from the front end position. The storage sensor b is, for example, a proximity switch provided on the slider 12, which turns on when it detects a front dog (not shown) attached to the guide rail 11 and turns off when it does not detect the front dog. The front dog is attached, for example, to the front part of the guide rail 11. The position of the rear end of the front dog coincides with the position of the storage sensor b when the slider 12 is at a predetermined distance from the front end position, and is naturally forward of the front end of the rear dog. The front dog extends forward from its rear end and covers the position of the storage sensor b when the slider 12 is at the front end position. This allows the storage sensor b to detect that the load receiving platform 5 is located within the predetermined distance from the front end position.

[0030] Gate sensor The gate sensor c is a sensor that detects whether the receiving tray 5 is in a folded state. This gate sensor c can be, for example, an angle sensor that detects the angle of the hinge 8 (Fig. 2) relative to the base end receiving tray 6. In this embodiment, the "state in which the receiving tray 5 is folded" refers to a state in which the receiving surfaces of the base end receiving tray 6 and the tip end receiving tray 7 face each other, and the angle θ (Fig. 10) between the receiving surfaces is equal to or less than the set angle θ1. Therefore, when the detected angle (θ) of the gate sensor c becomes equal to or less than the set angle θ1, it can be determined that the receiving tray 5 is in a folded state.

[0031] Pressure sensors The pressure sensor d is a sensor that detects that the loading platform 5 is pressed against the guide rail 11 when the loading platform 5 is being stored, and is provided, for example, in the discharge line of the hydraulic pump 32 (Fig. 5). When the lift cylinder 24 extends and the loading platform 5 comes into contact with the guide rail 11, the pressure in the discharge line rises. Therefore, a threshold value (set value) is set for the detected pressure of the pressure sensor d, and when the detected pressure exceeds the threshold value, it can be determined that the loading platform 5 has come into contact with the guide rail 11. Although not specifically shown, the guide rail 11 and the loading platform 5 come into contact via a pad.

[0032] Tilt sensor Figure 6 is a diagram of the installation of the tilt sensor. Figure 6 shows the tilt sensor e as seen from the left side of the loading platform 5. The tilt sensor e shown in the figure is a sensor that measures the angle φ1 of the loading platform 5 relative to the direction of gravity, and is attached to the loading platform 5 via a bracket 9. A gyro sensor, for example, can be used as the tilt sensor e. However, in addition to gyro sensors, pendulum-type or float-type tilt sensors (sensors that detect the tilt of the loading platform 5 relative to a hanging weight or the liquid surface), acceleration sensors, inertial sensors, etc. can also be used as the tilt sensor e.

[0033] An example of the location of the receiving platform 5 where the tilt sensor e is installed is inside the stiffener 5a on either the left or right side of the base-end receiving platform 6 (the left side in this example). In this embodiment, the stiffener 5a is a hollow member, and one stiffener is provided in each of the left and right regions of the underside of the receiving platform 5 (the surface opposite the receiving surface). The left and right stiffeners 5a are divided longitudinally between the base-end receiving platform 6 and the tip-end receiving platform 7. Assuming that the receiving surface of the unfolded receiving platform 5 is horizontal, the stiffener 5a has a long, narrow triangular shape when viewed from the left and right, with the top surface horizontal and the thickness decreasing toward the rear (the rear end of the receiving platform 5) (Figure 8). In this embodiment, the tilt sensor e is housed in a relatively large front space inside the stiffener 5a.

[0034] Tilt sensor Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 4. The tilt sensors f1 and f2 will be described with reference to Fig. 7 as well as Figs.

[0035] Tilt sensors f1 and f2 are sensors that detect a state quantity related to the relative angle of the receiving platform 5 with respect to the guide rail 11 and the vehicle frame 1. The state quantity related to the relative angle of the receiving platform 5 with respect to the vehicle frame 1 is a value that changes with the tilt operation of the receiving platform 5 (base end receiving platform 6), and examples of this state quantity include the angle itself of the receiving platform 5 (base end receiving platform 6) as well as the amount of extension and contraction of the tilt cylinder 23. In this embodiment, proximity switches are used for tilt sensors f1 and f2, and an example is described in which tilt sensors f1 and f2 detect a predetermined stroke of the tilt cylinder 23 to determine whether the relative angle of the receiving platform 5 is within a set angle range. In this embodiment, tilt sensor f1 defines the lower limit of the set angle range, and tilt sensor f2 defines the upper limit of the set angle range.

[0036] In this embodiment, tilt sensors f1 and f2 are attached via bracket R1 to the tube of either the left or right (in this example, the right) tilt cylinder 23, and dogs D1 and D2 are attached via bracket R2 to the rod. It is desirable to provide tilt sensors f1 and f2 on the base end side of the tube and rod of tilt cylinder 23, and when the rod of tilt cylinder 23 is connected to slider 12, tilt sensors f1 and f2 are installed on the rod side and dogs D1 and D2 on the tube side.

[0037] Tilt sensors f1 and f2 are arranged so as not to overlap when viewed from the extension and retraction direction of tilt cylinder 23, and in this embodiment, tilt sensors f1 and f2 are arranged so as to be offset in the radial direction of the tube of tilt cylinder 23 (FIG. 7). Tilt sensors f1 and f2 may also be arranged so as to be offset in the circumferential direction of the tube of tilt cylinder 23. Similarly, dogs D1 and D2 are also arranged so as not to overlap when viewed from the extension and retraction direction of tilt cylinder 23. The arrangement of dogs D1 and D2 when viewed from the extension and retraction direction of tilt cylinder 23 corresponds to the arrangement of tilt sensors f1 and f2 (FIG. 7).

[0038] Dogs D1 and D2 are bar-shaped members (channel members in this example) that are long in the extension and retraction direction of tilt cylinder 23, and are fixed to bracket R2 with bolts B that are passed through elongated holes. This allows the positions of dogs D1 and D2 to be adjusted in the extension and retraction direction of tilt cylinder 23 to meet specified conditions.

[0039] The positioning of the dogs D1 and D2 will now be described. When setting the positions of the dogs D1 and D2, first place the receiving platform 5 in the stored state as shown in FIG. 2, and then drive the tilt cylinder 23 to tilt the receiving platform 5 so that the receiving surface of the base-end receiving platform 6 is at a predetermined angle (for example, parallel to the reference plane) with the upper surface of the guide rail 11 as the reference plane. In this state, move the dog D1 in the contraction direction of the tilt cylinder 23 to approach the tilt sensor f1, and tighten the bolt B to fix the dog D1 to the bracket R2 at a position where the tilt sensor f1 detects the dog D1 and the output of the tilt sensor f1 changes from off to on. Thereafter, slightly extend the tilt cylinder 23 to tilt the receiving surface of the base-end receiving platform 6 forward by a small angle (for example, about 2 degrees). In this state, move dog D2 in the contraction direction of tilt cylinder 23 to approach tilt sensor f2, and tighten bolt B to fix dog D2 to bracket R2 at a position where tilt sensor f2 detects dog D2 and the output of tilt sensor f2 changes from off to on.

[0040] As a result, when tilt sensor f1 is off and tilt sensor f2 is on, it can be determined that the relative angle of the receiving surface of the base end receiving platform 6 with respect to the upper surface of the guide rail 11 is within the above-mentioned set angle range. In this embodiment, when the relative angle of the receiving surface of the base end receiving platform 6 with respect to the guide rail 11 is within the above-mentioned set angle range of about 2 degrees, this is considered to mean that the receiving platform 5 is parallel to the guide rail 11 and the vehicle frame 1. Note that if the receiving platform 5 is tilted backward (rear end lowered) with respect to the guide rail 11 outside the set angle range, the outputs of tilt sensors f1 and f2 are both on. Conversely, if the receiving platform 5 is tilted forward (rear end raised) with respect to the guide rail 11 outside the set angle range, the outputs of tilt sensors f1 and f2 are both off.

[0041] -Operation- Figure 8 is an explanatory diagram of the operation of the loading platform 5 by the lift cylinder 24, Figure 9 is an explanatory diagram of the operation of the loading platform 5 by the tilt cylinder 23, and Figure 10 is an explanatory diagram of the unfolding work of the loading platform 5. The operation of the loading platform lifting device 4 will be explained with reference to these figures as appropriate. The operation described below is performed by the control device 50 driving the control valves 33-35 and the electric motor 31 in response to an operation signal from the operating device 40. Furthermore, the loading platform lifting device 4 operates only while the switch of the operating device 40 is being operated, and stops when the operator takes their hand off the switch of the operating device 40.

[0042] Loading and unloading operations The loading operation is performed under the condition that the loading platform 5 is in an unfolded state, specifically, that the rear end sensor a is on and the gate sensor c is off. For example, when a raising operation is performed using the operation device 40, the control device 50 issues commands to the electric motor 31 and control valve 35 in response to a raising operation signal, driving the electric motor 31 to drive the hydraulic pump 32 and also driving the control valve 35 to connect the lift cylinder 24 to the hydraulic pump 32. This causes hydraulic oil to be supplied to the lift cylinder 24, which then extends, raising the loading platform 5 as shown in FIG. 8. When a lowering operation is performed using the operation device 40, the control device 50 issues a command to the control valve 35 in response to a lowering operation signal, stopping the electric motor 31 and the hydraulic pump 32 and also driving the control valve 35 to connect the lift cylinder 24 to the hydraulic oil tank 36. This causes hydraulic oil to be discharged from the lift cylinder 24 due to the weight of the loading platform 5, causing the lift cylinder 24 to contract and lower the loading platform 5 as shown in FIG. 8.

[0043] When the loading platform 5 is in the grounded state, there is no change in the command signal output by the control device 50 in response to the operation signal or the operation of the hydraulic circuit, but because the loading platform 5 is supported on the ground, the link 21 rotates as the lift cylinder 24 extends and retracts. This causes the arm 22 to move backward relative to the tilt cylinder 23, the parallel link deforms, the loading platform 5 tilts, and the entire underside of the stiffener 5a comes into contact with the ground, bringing the rear end of the loading surface close to the ground (Figure 8). This state makes it easier for the cart to move between the ground and the loading surface.

[0044] Furthermore, when a forward tilt operation is performed using the operating device 40, the control device 50 issues commands to the electric motor 31 and control valve 34 in response to a forward tilt operation signal, driving the electric motor 31 to drive the hydraulic pump 32 and also driving the control valve 34 to connect the tilt cylinder 23 to the hydraulic pump 32. As a result, hydraulic oil is supplied to the tilt cylinder 23, causing the tilt cylinder 23 to extend and tilt the platform 5 forward, as shown in FIG. 9. When a backward tilt operation is performed using the operating device 40, the control device 50 issues a command to the control valve 34 in response to the backward tilt operation signal, stopping the electric motor 31 and driving the control valve 34 to connect the tilt cylinder 23 to the hydraulic oil tank 36. As a result, hydraulic oil is discharged from the tilt cylinder 23 due to the weight of the platform 5, causing the tilt cylinder 23 to contract and tilt the platform 5 backward, as shown in FIG. 9. This operation is useful, for example, when parking the vehicle on a slope and tilting the loading platform 5 forward (tilt up) or backward (tilt down) relative to the vehicle so that the loading platform 5 is horizontal. Also, if the loading platform 5 is configured to be able to tilt forward (stand up) vertically, it becomes possible to raise the loading platform 5 close to the floor of the loading platform 3, stand the loading platform 5 up, and take a storage position along the rear surface of the loading platform 3.

[0045] ·Unfolding operation The unfolding operation of the loading platform lifting device 4 is an operation in which the loading platform 5 in the stored state is pulled out from under the vehicle frame 1 and lowered to the ground by sequence control of the lift cylinder 24 and the slide cylinder 14. This unfolding operation is executed by a lowering operation performed by the operating device 40, provided that the gate sensor c is on. The unfolding operation in this embodiment includes a first pull-out operation, a first lowering operation, a second pull-out operation, and a second lowering operation, and the loading platform 5 is lowered in steps from the stored position to the ground, as shown by the arrows in FIG. 1.

[0046] In the first withdrawal operation, the control device 50 extends the slide cylinder 14, withdrawing the loading platform 5 rearward from the storage position to a position where the storage sensor b switches off, and then stops the slide cylinder 14. In the first lowering operation following the first withdrawal operation, the control device 50 retracts the lift cylinder 24, lowering the loading platform 5 to a height where the gate sensor c switches off, and then stops the lift cylinder 24. In the second withdrawal operation following the first lowering operation, the control device 50 again extends the slide cylinder 14, withdrawing the loading platform 5 to a position where the rear end sensor a switches on, and then stops the slide cylinder 14. In the second lowering operation following the second lowering operation, the control device 50 again retracts the lift cylinder 24, and lowering the loading platform 5 until it touches the ground.

[0047] Once the receiving platform 5 has touched the ground, the front receiving platform 7, which is leaning against the guide rollers 13 (in the figure, the guide rollers 13 are hidden by the vehicle bumper), is pulled down as shown in Figure 10 to unfold the receiving platform 5 horizontally. The front receiving platform 7 is manually tilted, but it may also be configured so that a separate drive device such as a cylinder is provided and the front receiving platform 7 is opened by the drive device.

[0048] Storage operation The storage operation of the loading platform lifting device 4 involves pulling the loading platform 5 on the ground under the vehicle frame 1 and storing it by sequential control of the lift cylinder 24 and slide cylinder 14. This storage operation is performed on the condition that the rear end sensor a is on and the loading platform 5 is folded up. Therefore, a preparatory operation must be performed in advance to lean the front loading platform 7, which is opened horizontally on the ground, against the guide roller 13 in the direction opposite to the arrow in Figure 10. This preparatory operation is performed manually, but a separate driving device such as a cylinder may be provided to close the front loading platform 7. By performing this preparatory operation, the angle θ between the loading surfaces of the base loading platform 6 and the front loading platform 7 decreases as the loading platform 5 rises in response to the lifting operation. When the loading platform 5 reaches a predetermined height, the loading platform 5 is folded up and the gate sensor c switches from off to on.

[0049] The storage operation of this embodiment includes a first lifting operation, a first retracting operation, a second lifting operation, and a second retracting operation, and the loading platform 5 moves in steps from the ground to the storage position, just like the unfolding operation. In the first lifting operation, the control device 50 extends the lift cylinder 24 to raise the loading platform 5 from the ground to a height where the gate sensor c turns on. In the first retracting operation following the first lifting operation, the control device 50 retracts the slide cylinder 14 to retract the loading platform 5 forward to a position where the storage sensor b turns on. In the second lifting operation following the first retracting operation, the control device 50 again extends the lift cylinder 24 to raise the loading platform 5 until the pressure sensor d turns on. In the second retracting operation following the second lifting operation, the control device 50 again retracts the slide cylinder 14 to move the loading platform 5 forward to the front end position, thereby achieving the storage state.

[0050] - Loading of receiving platform begins - In this embodiment, the loading platform 5 transitions from a lifting operation (first lifting operation in this example) to a retracting operation (first retracting operation in this example) on the condition that the loading platform 5 is parallel to the guide rail 11 (the above-mentioned relative angle is within the set angle range). Specifically, when switching the operation of the loading platform 5 from a lifting operation to a retracting operation, the control device 50 determines whether the loading platform 5 is in a folded state based on the output of the gate sensor c, and determines whether the relative angle of the loading platform 5 is within the set angle range based on the outputs of the tilt sensors f1 and f2. Then, on the condition that the loading platform 5 is in a folded state and the relative angle of the loading platform 5 is within the set angle range, the control device 50 contracts the slide cylinder 14 in response to a lifting operation signal input from the operation device 40 in association with the lifting operation, and retracts the loading platform 5 to the bottom of the vehicle frame 1.

[0051] At this time, in this embodiment, when the loading platform 5 is in the folded state and the relative angle of the loading platform 5 is outside the set angle range, the control device 50 automatically adjusts the relative angle of the loading platform 5 so that the loading platform 5 is parallel to the guide rail 11. If the loading platform 5 and the guide rail 11 are not parallel when the loading platform 5 transitions to the folded state, the control device 50 controls the tilt cylinder 23 between stopping the lift cylinder 24 and driving the slide cylinder 14. After the relative angle of the loading platform 5 is thereby brought within the set angle range, the control device 50 drives the slide cylinder 14 to retract the loading platform 5 below the vehicle frame 1. All of the series of steps in the storage operation of the loading platform 5 are executed in response to the lifting operation, and this automatic adjustment of the relative angle of the loading platform 5 is also executed automatically under predetermined conditions during the lifting operation.

[0052] A specific control procedure for the controller 50 to start the retraction operation of the receiving platform 5 will be exemplified below.

[0053] Fig. 11 is a flowchart showing the control procedure for the retraction start operation of the receiving platform by the control device 50. The flow explained in Fig. 11 corresponds to the sequence from the start of the first lifting operation in the aforementioned storage operation until switching to the first retracting operation, and the input determination of the lifting operation signal (step S11) is repeatedly executed at a predetermined cycle time (e.g., 0.1 s). The flow in the same figure shows only the operation of the lifting operation performed by the operator with the intention of storing the receiving platform 5 after the aforementioned preparatory work of leaning the leading end receiving platform 7 against the guide roller 13, and does not show the operation when, for example, storing is stopped and changed to a lowering operation midway.

[0054] First, the control device 50 determines whether a lifting operation is being performed based on whether a lifting operation signal has been input (step S11). If a lifting operation is not being performed and a lifting operation signal has not been input, the control device 50 does not output a command to the power unit 30 (or stops outputting the command) and returns the procedure to step S11 (step S12). Therefore, while a lifting operation is not being performed, the processes of steps S11 and S12 are repeated and the loading platform 5 is in a stopped state. If a lifting operation is being performed and a lifting operation signal has been input, the control device 50 determines whether the rear end sensor a is on (step S13). If the rear end sensor a is off, the control device 50 returns the procedure to step S11, but it is assumed that the rear end sensor a is on at the start of storage after the loading and unloading operation, and the determination in step S13 is satisfied.

[0055] After confirming that the rear end sensor a is on, the control device 50 determines whether the gate sensor c is on (step S14). If the receiving platform 5 has not transitioned to the folded state and the gate sensor c is off, the control device 50 commands the receiving platform 5 to rise and returns to step S11 (step S15), and repeats steps S11-S15 until the gate sensor c turns on. If, while repeating steps S11-S15, the receiving platform 5 rises and transitions to the folded state and the gate sensor c turns on, the control device 50 stops the rise command and stops the lifting operation of the receiving platform 5 (step S16).

[0056] After stopping the lifting operation of the receiving platform 5, the control device 50 determines whether the tilt sensor f1 is OFF (step S17). At that time, if the length of the tilt cylinder 23 is shorter than the appropriate range and the base-end receiving platform 6 is tilted backward outside the set angle range relative to the guide rail 11 (if the rear end side is lowered), the tilt sensor f1 turns ON. In this case, the control device 50 executes a tilt-up command (a command to extend the tilt cylinder 23) and returns to step S11 (step S18), and the steps S11-S18 are repeated. While the receiving platform 5 is tilting up by repeating the steps S11-S18, if the relative angle of the receiving platform 5 with respect to the guide rail 11 matches the lower limit of the set angle range and the tilt sensor f1 turns OFF, the control device 50 stops the tilt-up command (step S19).

[0057] If it is determined in step S17 that tilt sensor f1 is off, the control device 50 determines whether tilt sensor f2 is on (step S20). If the length of the tilt cylinder 23 is longer than the appropriate range and the base-end receiving platform 6 is tilted forward relative to the guide rail 11 outside the set angle range (if the rear end side is raised), tilt sensor f2 turns off. In this case, the control device 50 executes a tilt-down command (a command to retract the tilt cylinder 23) and returns to step S11 (step S21), and the steps S11-S21 are repeated. While the receiving platform 5 is tilting down by repeating the steps S11-S21, if the relative angle of the receiving platform 5 relative to the guide rail 11 matches the upper limit of the set angle range and tilt sensor f2 turns on, the control device 50 stops the tilt-down command (step S22).

[0058] The order of steps S17-S19 and S20-S22 may be reversed. When the relative angle of the base-end receiving platform 6 with respect to the guide rail 11 falls within the set angle range as a result of the tilt-up operation of steps S17-S19 or the tilt-down operation of steps S20-S22, the conditions of both steps S17 and S20 are satisfied. Furthermore, if the length of the tilt cylinder 23 falls within the appropriate range at the start of the storage operation, the conditions of steps S17 and S20 are satisfied without the need to adjust the angle of steps S17-S22. When the conditions of steps S17 and S20 are satisfied, the control device 50 contracts the slide cylinder 14 while stopping the tilt cylinder 23 and the lift cylinder 24, thereby transitioning the operation of the receiving platform 5 from the raising operation to the retracting operation.

[0059] -effect- (1) The loading platform lifting device 4 of this embodiment is of an underfloor storage type, yet allows the loading platform 5 to be tilted as desired, and by appropriately tilting the loading platform 5 relative to the vehicle, loading and unloading operations can be performed with the loading platform 5 kept horizontal, even when the vehicle is parked on a slope. However, because the loading platform lifting device 4 is of an underfloor storage type, the loading platform 5 must be stored as close as possible to the vehicle frame 1 in order to ensure the vehicle departure angle. In this state where the loading platform 5 and the vehicle frame 1 are close to each other, unless the loading platform 5 is accurately parallel to the guide rails 11, there is a risk that the loading platform 5 will interfere with surrounding structures when stored.

[0060] In contrast, in this embodiment, the receiving platform 5 is retracted under the floor on the condition that the relative angle of the receiving platform 5 with respect to the guide rail 11 is within a set angle range. Therefore, for example, when the receiving platform 5 is tilted for use and then returned to its original angle to be stored under the floor, it is possible to avoid the receiving platform 5 being retracted under the floor when the relative angle with respect to the guide rail 11 is not within the set angle range. Therefore, the receiving platform 5 can be properly stored under the floor while maintaining the tilt function of the receiving platform 5.

[0061] Although not specifically shown, the receiving platform 5 is locked to a fall prevention member in the stored state. The fall prevention member is described in detail in JP 2019-55747 A. If the receiving platform 5 is tilted outside the set angle range, the receiving platform 5 may not properly engage with the fall prevention member. If the receiving platform 5 is left in an improperly locked state for a long period of time, the receiving platform 5 may gradually descend due to a leak of hydraulic oil in the lift cylinder 24 or tilt cylinder 23.

[0062] In contrast, in this embodiment, the receiving platform 5 is pulled under the floor with its relative angle to the guide rail 11 within the set angle range, so that the receiving platform 5 can be properly engaged with the fall prevention member when transitioning to the storage state.

[0063] (2) In this embodiment, when the receiving platform 5 transitions to the folded state during the storage operation, if the relative angle of the receiving platform 5 is outside the set angle range, the tilt cylinder 23 is driven to automatically adjust the angle of the receiving platform 5, and then the retraction operation of the receiving platform 5 is executed. This allows the receiving platform 5 to be stored smoothly and appropriately without having to manually adjust the angle of the receiving platform 5 by driving the tilt cylinder 23.

[0064] (3) Since the tilt sensors f1 and f2 are configured to detect the stroke of the tilt cylinder 23, it is possible to determine whether the relative angle of the loading platform 5 with respect to the guide rail 11 is within the set angle range using a relatively inexpensive proximity switch.

[0065] However, as long as the stroke of the tilt cylinder 23 is determined, a non-contact type rangefinder that measures the distance to the target object using a laser or the like can also be used. For example, a rangefinder can be installed as a tilt sensor on the tube of the tilt cylinder 23, and the stroke of the tilt cylinder 23 can be measured by using the rangefinder to measure the distance to the target structure on the rod side. In this case, one tilt sensor is sufficient. Also, even when a proximity switch is used, it is possible to reduce the number of tilt sensors to one by, for example, shortening the dog so that the dog passes through the detection range of the proximity switch during the extension and retraction of the tilt cylinder 23. In other words, the dog overlaps the detection range of the proximity switch only when the relative angle of the load receiving platform 5 is within the set angle range. The same applies to the second and third embodiments.

[0066] Second Embodiment 12 is a flowchart showing the control procedure for the retraction start operation of the receiving platform 5 by the control device provided in the receiving platform lifting device according to the second embodiment of the present invention. In the figure, the same steps as the control procedure for the retraction start operation in the first embodiment are assigned the same numbers as in FIG. 11, and the explanation will be omitted or simplified.

[0067] This embodiment differs from the first embodiment in that when the receiving platform 5 is in a folded state and the relative angle of the receiving platform 5 with respect to the guide rail 11 is outside the set angle range, the control device 50 commands the alarm output device A to output an alarm. In this embodiment, when the receiving platform 5 is outside the set angle range, the tilt-up command and its stop command, and the tilt-down command and its stop command (steps S18, S19, S21, S22 in FIG. 11) are not executed, and these steps are omitted.

[0068] 12, the procedure of steps S11-S17 is the same as that of the first embodiment. If the receiving platform 5 is tilted backward outside the set angle range and the tilt sensor f1 is on when the receiving platform 5 is folded, the control device 50 commands the notification output device A to output a notification (alarm) and returns the procedure to step S11 (step S23). Also, if the receiving platform 5 is tilted forward outside the set angle range and the tilt sensor f2 is off when the receiving platform 5 is folded, the control device 50 commands the notification output device A to output a notification (alarm) and returns the procedure to step S11 (step S24). The notification output operations commanded in steps S23 and S24 may be the same operation of the notification output device A, or different operations may be used so that the operator is informed of whether the receiving platform 5 is tilted forward or backward, i.e., whether the platform should be tilted down or tilted up. Furthermore, the order of determination in steps S17 and S20 may be reversed, or steps S17 and S20 may be performed simultaneously.

[0069] If the receiving platform 5 has transitioned to the folded state but is not parallel to the guide rail 11, even if a lifting operation is performed, the control device 50 repeats the procedure of steps S11-S24 and notifies the operator that the receiving platform 5 is tilted without driving the receiving platform 5. If the operator then performs a forward or backward tilting operation, manually adjusts the angle so that the receiving platform 5 is parallel to the guide rail 11, and then performs a lifting operation again, the determination of steps S17 and S20 is satisfied, and the control device 50 proceeds to the retracting operation of the receiving platform 5. If the determination of steps S17 and S20 is satisfied at the time the receiving platform 5 has transitioned to the folded state without the operator having to manually adjust the angle of the receiving platform 5, the control device 50 proceeds to the retracting operation of the receiving platform 5 without issuing a notification output operation command (steps S23 and S24).

[0070] In other respects, this embodiment is similar to the first embodiment, including the hardware configuration of the loading platform lifting and lowering device 4.

[0071] In this embodiment as well, the receiving platform 5 is retracted under the floor on the condition that the relative angle of the receiving platform 5 with respect to the guide rail 11 is within the set angle range, so the receiving platform 5 can be stored properly under the floor while maintaining the tilt function of the receiving platform 5. Furthermore, by outputting a notification output operation via the notification output device A to notify the operator that the relative angle of the receiving platform 5 is outside the set angle range, the operator is actively prompted to adjust the angle of the receiving platform 5, and the receiving platform 5 can be stored while avoiding interference with obstacles.

[0072] <Third embodiment> 13 is a flowchart showing the control procedure for the retraction start operation of the receiving platform 5 by the control device provided in the receiving platform lifting device according to the third embodiment of the present invention. In the figure, the same steps as the control procedure for the retraction start operation in the second embodiment are assigned the same numbers as in FIG. 12, and the explanation will be omitted or simplified.

[0073] This embodiment differs from the second embodiment in that the procedure (steps S23 and S24 in FIG. 12) of notifying the operator that the relative angle of the receiving platform 5 with respect to the guide rail 11 is outside the set angle range when the receiving platform 5 transitions to the folded state is omitted. In this embodiment, as in the second embodiment, control of the tilt cylinder 23 is not executed when the receiving platform 5 is outside the set angle range, and there are no procedures corresponding to steps S18, S19, S21, and S22 in FIG. 11. In other words, when the relative angle of the receiving platform 5 is outside the set angle range, the control device 50 simply disables (applies an interlock to) the operation of the slide cylinder 14 in response to the lifting operation signal.

[0074] 13, the procedure of steps S11-S20 is the same as that of the second embodiment. If the receiving tray 5 is tilted backward outside the set angle range and the tilt sensor f1 is on when the receiving tray 5 is folded, the control device 50 returns to step S11 without outputting a command to either the power unit 30 or the notification output device A (step S17). Also, if the receiving tray 5 is tilted forward outside the set angle range and the tilt sensor f2 is off when the receiving tray 5 is folded, the control device 50 returns to step S11 without issuing a command to either the power unit 30 or the notification output device A (step S20). The order of determination in steps S17 and S20 may be reversed, or they may be performed together.

[0075] If the receiving platform 5 has transitioned to the folded state but is not parallel to the guide rail 11, the control device 50 repeats the procedure of steps S11-S20 even if a lifting operation is performed, and does not drive either the receiving platform 5 or the alarm output device A. If the operator then performs a forward or backward tilting operation, manually adjusts the angle of the receiving platform 5 so that it is parallel to the guide rail 11, and then performs a lifting operation again, the determinations of steps S17 and S20 are satisfied, and the control device 50 proceeds to the retracting operation of the receiving platform 5. If the determinations of steps S17 and S20 are satisfied at the time the receiving platform 5 has transitioned to the folded state without the need to manually adjust the angle of the receiving platform 5, the control device 50 proceeds to the retracting operation of the receiving platform 5 without performing the interlock procedure (returning to step S11).

[0076] In other respects, this embodiment is similar to the first and second embodiments, including the hardware configuration of the loading platform lifting and lowering device 4.

[0077] In this embodiment as well, if the loading platform 5 is not parallel to the guide rails 11, even if an operator attempts to lift the loading platform 5 in order to store it, the loading platform 5 will not move once it has transitioned to the folded state. Furthermore, unless the operator adjusts the angle of the loading platform 5 so that it is parallel to the guide rails 11, the loading platform 5 will not be retracted under the vehicle frame 1. In this embodiment as well, the loading platform 5 can be properly stored under the floor while still having the tilt function of the loading platform 5.

[0078] <Fourth embodiment> Fig. 14 is a hydraulic circuit diagram showing one example of the configuration of a power unit provided in a platform lifting device according to a fourth embodiment of the present invention. This figure corresponds to Fig. 5 of the first embodiment, and elements similar to those in the first embodiment are given the same reference numerals as in Fig. 5, and their explanations will be omitted.

[0079] This embodiment differs from the first embodiment in that the relative angle of the receiving platform 5 with respect to the guide rail 11 is calculated, and the calculated value is used to determine whether the receiving platform 5 is within a set angle range with respect to the guide rail 11. In the first to third embodiments, the stroke of the tilt cylinder 23 is detected to determine the relative angle of the receiving platform 5 with respect to the guide rail 11, but in this embodiment, the relative angle of the receiving platform 5 with respect to the guide rail 11 is calculated. To achieve this, in this embodiment, instead of tilt sensors f1 and f2, which are proximity switches, a second tilt sensor e' is used as a tilt sensor together with the first tilt sensor e described above.

[0080] The inclination sensor e' can be a sensor of the same type as the inclination sensor e. The output of the inclination sensor e' is input to the control device 50. The inclination sensor e' is installed on the slide unit 10 (for example, the guide rail 11, which is a stationary body) or the vehicle frame 1, whose inclination angle with respect to the vehicle frame 1 is constant. That is, the inclination sensor e' measures the angle φ2 of the vehicle frame 1 or the guide rail 11 with respect to the direction of gravity. Since the angle φ1 of the loading platform 5 with respect to the direction of gravity is measured by the inclination sensor e installed on the loading platform 5, the control device 50 can calculate the relative angle α of the loading platform 5 to the guide rail 11 by calculating the difference between the angles φ1 and φ2 measured by the inclination sensors e and e'. In this embodiment, a lower limit value α1 and an upper limit value α2 of the set angle range for the relative angle α are stored in the memory of the control device 50. The control device 50 compares the calculated relative angle α with the lower limit value α1 and upper limit value α2 to determine whether the relative angle α of the receiving platform 5 with respect to the guide rail 11 is within the set angle range (α1 to α2).

[0081] 15 is a flowchart showing the control procedure for the retraction start operation of the receiving platform 5 by the control device provided in the receiving platform lifting device according to the fourth embodiment of the present invention. In the figure, the same steps as the control procedure for the retraction start operation in the first embodiment are assigned the same numbers as in FIG. 11, and the explanation will be omitted or simplified.

[0082] Explaining the flow of FIG. 15, first, the procedure of steps S11-S16 is the same as in the first embodiment. In this embodiment, when the receiving platform 5 transitions to the folded state and stops its upward movement (step S16), the control device 50 calculates the relative angle α of the receiving platform 5 with respect to the guide rail 11 based on the output of the tilt sensors e and e' (step S16a). In this embodiment, instead of determining whether the tilt sensors f1 and f2 are on or off (steps S17 and S20 in FIG. 11), the control device 50 determines whether the relative angle α is equal to or greater than the lower limit α1 (step S17') and whether the relative angle α is equal to or less than the upper limit α1 (step S20'). If the receiving platform 5 is tilted backward outside the set angle range and α is below the lower limit α1, a tilt-up command is issued and the procedure returns to step S11 (step S18). As a result, if the relative angle α becomes equal to or greater than the lower limit α1, the tilt-up command is stopped (step S19). Conversely, if the receiving platform 5 is tilted forward outside the set angle range and α exceeds the upper limit value α2, a tilt-down command is issued and the procedure returns to step S11 (step S21). As a result, if the relative angle α falls below the upper limit value α2, the tilt-up command is stopped (step S22). If the relative angle α of the receiving platform 5 falls within the set angle range (α1≦α≦α2) and the determinations of steps S17' and S20' are both satisfied, the control device 50 proceeds to the retraction operation of the receiving platform 5.

[0083] The order of steps S17', S18, and S19 and steps S20', S21, and S22 may be interchanged.

[0084] This embodiment is similar to the first embodiment except for the points described above.

[0085] In this embodiment, as in the first embodiment, the receiving platform 5 is retracted under the floor on the condition that the relative angle of the receiving platform 5 with respect to the guide rail 11 is within the set angle range. Therefore, the receiving platform 5 can be properly stored under the floor while maintaining the tilt function of the receiving platform 5.

[0086] Furthermore, in this embodiment, unlike the first embodiment, the two tilt sensors f1 and f2 (proximity switches) can be omitted instead of providing the tilt sensor e', which has the advantage of reducing the number of sensors and parts compared to the first embodiment.

[0087] In this embodiment, as an example of processing when the relative angle α calculated based on the outputs of the tilt sensors e and e' is outside the set angle range, the tilt cylinder 23 is controlled as in the first embodiment. However, it is of course also possible to notify the operator as in the second embodiment, or to simply execute an interlock as in the third embodiment.

[0088] Furthermore, in this embodiment, a configuration has been exemplified in which two tilt sensors e and e' are used to calculate the relative angle α of the load receiving platform 5 relative to the guide rail 11, but the method of calculating the relative angle α is not limited to this example. For example, it is also possible to provide a first angle sensor that detects the angle of the arm 22 relative to the slide unit 10 (slider 12, etc.) and a second angle sensor that detects the angle of the base end side load receiving platform 6 relative to the arm 22, and calculate the relative angle α based on the outputs of these angle sensors.

[0089] Also, instead of calculating the relative angle α, a configuration can be adopted in which a proximity switch is used to detect the set angle range. For example, a configuration can be provided in which a first proximity switch is turned on (or off) when the arm 22 is at an angle within a predetermined range relative to the slider 12, and a second proximity switch is turned on (or off) when the base-end receiving platform 6 is at an angle within a predetermined range relative to the arm 22. In other words, if the two proximity switches are configured to turn on and off in a predetermined combination when the relative angle α of the receiving platform 5 with respect to the guide rail 11 is in an appropriate position within the set angle range, the set angle range can be detected by the proximity switch.

[0090] Fifth Embodiment Fig. 16 is a flowchart showing the control procedure for the retraction start operation of the loading platform by the control device provided in the loading platform lifting device according to the fifth embodiment of the present invention. In the figure, the same steps as those in the control procedure for the retraction start operation in the first embodiment are assigned the same numbers as in Fig. 11, and the explanations thereof will be omitted or simplified.

[0091] This embodiment differs from the first embodiment in that the control device 50 retracts the loading platform 5 into the lower part of the vehicle frame 1 on the condition that the loading platform 5 is in a folded state and the relative angle of the loading platform 5 with respect to the guide rail 11 falls within a set angle range from a specific direction, either above or below. The condition for transitioning to the retracting operation of the loading platform 5 can also be set so that the loading platform 5 falls within a set angle range from a backward tilted position, but in this embodiment, the condition is that the loading platform 5 falls within a set angle range from a forward tilted position.

[0092] Specifically, when the loading platform 5 transitions to the folded state, if the relative angle is outside the set angle range and the loading platform 5 is tilted forward, the control device 50 drives the tilt cylinder 23 in response to a storage operation signal to tilt the loading platform 5 backward and make it horizontal, just like in the first embodiment. After the relative angle of the loading platform 5 is thus brought within the set angle range, the control device 50 contracts the slide cylinder 14 to retract the loading platform 5 into the lower part of the vehicle frame 1.

[0093] When the loading platform 5 transitions to the folded state, if the relative angle is outside the set angle range and the loading platform 5 is not tilted forward, the control device 50 drives the tilt cylinder 23 in response to a storage operation signal to tilt the loading platform 5 forward once and then level it. The cases where the relative angle is outside the set angle range and the loading platform 5 is not tilted forward include when the relative angle is within the set angle range and the loading platform 5 is level, and when the relative angle is outside the set angle range and the loading platform 5 is tilted backward. In these cases, the control device 50 first causes the loading platform 5 to be tilted forward once the relative angle is outside the set angle range, then brings the relative angle of the loading platform 5 back into the set angle range, and then retracts the slide cylinder 14 to retract the loading platform 5 into the bottom of the vehicle frame 1.

[0094] Explaining the flow of FIG. 16, first, the procedure of steps S11-S16 is the same as in the first embodiment. In this embodiment, when the receiving platform 5 transitions to the folded state and stops its upward movement (step S16), the control device 50 determines whether tilt sensors f1 and f2 are both off (step S17"). Step S17" is a procedure for determining whether the receiving platform 5 is in a forward tilted position, and if tilt sensor f2 is off, tilt sensor f1 will inevitably also be off. As a result, step S17" is equivalent to determining whether tilt sensor f2 is off, and the same algorithm as step S17 in FIG. 11 (first embodiment) can be applied.

[0095] When the receiving platform 5 is in a forward tilted position and tilt sensor f2 is off, the control device 50 executes a tilt down command (step S21) and determines whether tilt sensor f2 has turned on (step S21a). If tilt sensor f2 turns on while repeating the procedures of steps S21 and S21a, the control device 50 stops the tilt down command (step S22) and proceeds to the retraction operation of the receiving platform 5. The receiving platform 5 tilts down from a forward tilted position and the retraction operation begins when tilt sensor f2 turns on, so the receiving platform 5 is retracted in a horizontal position (a position in which tilt sensor f2 is on and tilt sensor f1 is off).

[0096] On the other hand, if the receiving platform 5 is in a horizontal position (tilt sensor f2 is on and tilt sensor f1 is off) or a backward tilted position (tilt sensors f1 and f2 are both on) at the time the lift command is stopped, the control device 50 executes a tilt-up command (step S18). In this embodiment, unless the receiving platform 5 is determined to be in a forward tilted position at this time, even if it is determined to be in a horizontal position, the control device 50 tilts up the receiving platform 5 and temporarily shifts it to a forward tilted position. The control device 50 confirms that the lifting operation is continuing while issuing the tilt-up command (step S18a), and determines whether the elapsed time since the tilt sensor f2 turned off due to the tilt-up operation has reached the delay time (a very short set value) (step S18b). If the lifting operation is interrupted before the delay time has elapsed after the tilt sensor f2 turned off, the control device 50 stops the operation of the receiving platform lifting / lowering device 4 (step S18c) and returns to step S11. When a delay time has elapsed since tilt sensor f2 turned off due to tilt-up and the loading platform 5 has tilted forward slightly, the control device 50 stops the tilt-up command (step S19) and returns the procedure to step S11. When the procedure returns to step S11, if a lifting operation has been performed, the determinations of steps S11, S13, S14, and S17" are satisfied. Therefore, after stopping the tilt-up command (step S19), the control device 50 proceeds to a tilt-down command (step S21), and proceeds through the procedures of steps S21, S21a, and S22 as described above to a command to retract the loading platform 5.

[0097] This embodiment is similar to the first embodiment except for the points described above.

[0098] In this embodiment, as in the first embodiment, the receiving platform 5 is retracted under the floor on the condition that the relative angle of the receiving platform 5 with respect to the guide rail 11 is within the set angle range. Therefore, the receiving platform 5 can be properly stored under the floor while maintaining the tilt function of the receiving platform 5.

[0099] Furthermore, even when the receiving platform 5 is determined to be horizontal, slight variations in the angle of the receiving platform 5 may occur depending on whether the platform is tilted down to fit within the set angle range from above or tilted up to fit within the set angle range from below. Taking this into consideration, in this embodiment, the retraction operation of the receiving platform 5 is started on the condition that the receiving platform 5 fits within the set angle range from a specific direction. This further reduces variations in the angle of the receiving platform 5 during the retraction operation.

[0100] In particular, in this embodiment, the condition is set such that the receiving platform 5 falls within a set angle range from above as a result of tilting down. Tilting up is an operation performed by driving the hydraulic pump 32 to send hydraulic oil to the tilt cylinder 23. In contrast, tilting down is an operation that utilizes the weight of the receiving platform 5, as described above. In other words, the tilting up operation involves control of the control valve 34, the electric motor 31, and the hydraulic pump 32, and variations in the responsiveness of these devices can cause variations in the timing of stopping. In contrast, the tilting down operation is performed solely under the control of the control valve 34 and utilizes the weight of the receiving platform 5 without using any power, allowing for smooth stopping with good response, and reducing variations in the timing of stopping. Therefore, compared to when the condition is that the receiving platform 5 becomes horizontal as a result of tilting up, by setting the condition that the receiving platform 5 finally becomes horizontal as a result of tilting down, variations in the angle of the receiving platform 5 during the retracting operation can be more reasonably suppressed.

[0101] <Modification> It should be noted that the first to third and fifth embodiments can be said to be forms for determining whether the length of the tilt cylinder 23 is appropriate, and it is possible to determine whether the conditions of steps S17 (S17") and S20 (FIG. 11) are met even before the loading platform 5 transitions to the folded state. Therefore, the determinations of steps S17 (S17") and S20 may be performed before step S14, and after recognizing that the relative angle of the loading platform 5 is outside the set angle range, the angle of the loading platform 5 may be adjusted, an alarm may be sounded, or an interlock may be performed when the loading platform transitions to the folded state.

[0102] Furthermore, the first to fifth embodiments can be combined as appropriate. For example, the determination using the tilt sensors e and e' in the fourth embodiment can be applied instead of the determination using the tilt sensors f1 and f2 in the second, third, or fifth embodiment.

[0103] Furthermore, the essence of the invention is to perform the retraction operation while the relative angle of the loading platform 5 with respect to the guide rail 11 is within a set angle range, and the configuration and operation of the loading platform lifting device 4 can be modified as appropriate without departing from this concept. For example, the storage operation of the loading platform 5 has been described as including the steps of a first lifting operation, a first retracting operation, a second lifting operation, and a second retracting operation. However, the storage operation may be completed by simply retracting the loading platform 5 in a straight line from the rear end position to the front end position. Furthermore, the number of lifting operations and retracting operations required for the loading platform 5 to reach the storage position from the ground is not limited to two each and may be increased if necessary. Furthermore, although the application of the loading platform lifting device has been described as an application in which the loading platform 5 is retracted rearward of the vehicle frame 1, the present invention is also applicable to a configuration in which the loading platform 5 is retracted to the side (e.g., left side) of the vehicle frame 1. [Explanation of symbols]

[0104] 1...vehicle frame, 4...load receiving platform lifting device, 5...load receiving platform, 11...guide rail, 12...slider, 14...slide cylinder, 22...arm, 23...tilt cylinder, 24...lift cylinder, 40...operation device, 50...control device, A...alarm output device, c...gate sensor, e...tilt sensor (first tilt sensor), e'...tilt sensor (second tilt sensor), f1, f2...tilt sensors (proximity switch, sensor to detect stroke), α...relative angle, α1...lower limit value of set angle range, α2...upper limit value of set angle range

Claims

1. A guide rail attached to the bottom of the car frame, a slider that is movable back and forth along the guide rail; an arm pivotally connected to the slider; a load receiving platform rotatably connected to the tip of the arm; a lift cylinder that rotates the arm to raise and lower the loading platform; a slide cylinder that moves the loading platform back and forth together with the slider; a tilt cylinder that tilts the loading platform; a gate sensor that detects that the loading platform is in a folded state; a tilt sensor for detecting a state quantity relating to a relative angle of the loading platform with respect to the guide rail; an operating device for storing the loading platform; a control device that drives the lift cylinder and the tilt cylinder in accordance with a signal from the operation device to raise and lower and tilt the loading platform, The control device determining whether the loading platform is in a folded state based on the output of the gate sensor; determining whether the relative angle of the loading platform is within a set angle range based on the output of the tilt sensor; On the condition that the loading platform is in a folded state and the relative angle of the loading platform is within the set angle range, the slide cylinder is contracted in response to a storage operation signal input from the operation device in association with a storage operation, thereby making it possible to retract the loading platform into the lower part of the vehicle frame. A loading platform lifting device characterized by the above.

2. The loading platform lifting device according to claim 1, The control device is characterized in that, when the loading platform is in a folded state and the relative angle of the loading platform is outside the set angle range, it drives the tilt cylinder in response to the storage operation signal, brings the relative angle of the loading platform into the set angle range, and then retracts the loading platform into the lower part of the vehicle frame.

3. The loading platform lifting device according to claim 1, The control device is characterized in that, when the loading platform is in a folded state and the relative angle of the loading platform is outside the set angle range, it instructs the alarm output device to output an alarm indicating that the relative angle of the loading platform is outside the set angle range.

4. The loading platform lifting device according to claim 1, The loading platform lifting device is characterized in that the control device disables the operation of the slide cylinder in response to the storage operation signal when the relative angle of the loading platform is outside the set angle range.

5. The loading platform lifting device according to claim 1, The control device A loading platform lifting device characterized by pulling the loading platform into the lower part of the vehicle frame when the loading platform is in a folded state and the relative angle of the loading platform is within the set angle range from a specific direction, either above or below.

6. The loading platform lifting device according to claim 1, The control device When the loading platform is in a folded state and the relative angle is out of the set angle range and the loading platform is tilted forward, the tilt cylinder is driven in response to the storage operation signal, and the relative angle of the loading platform is brought into the set angle range, and then the loading platform is retracted into the lower part of the vehicle frame; When the loading platform is in a folded state, when the relative angle is within the set angle range and the loading platform is horizontal, and when the relative angle is outside the set angle range and the loading platform is tilted backward, the tilt cylinder is driven in response to the storage operation signal, causing the relative angle to be outside the set angle range and the loading platform to be tilted forward, and then the relative angle of the loading platform is brought within the set angle range and the loading platform is pulled into the lower part of the vehicle frame.

7. The loading platform lifting device according to any one of claims 1 to 6, The loading platform lifting device is characterized in that the tilt sensor is a sensor that detects the stroke of the tilt cylinder.

8. The loading platform lifting device according to any one of claims 1 to 6, The loading platform lifting device is characterized in that the control device calculates the relative angle of the loading platform with respect to the guide rail and determines whether the loading platform is within the set angle range with respect to the guide rail based on the calculated value.

9. The loading platform lifting device according to any one of claims 1 to 6, the tilt sensor includes a first tilt sensor that measures the angle of the loading platform relative to the direction of gravity, and a second tilt sensor that measures the angle of the vehicle frame relative to the direction of gravity, The loading platform lifting device is characterized in that the control device calculates the relative angle of the loading platform by taking the difference between the measured values ​​of the first tilt sensor and the second tilt sensor.

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