JP5822605B2 - Retractable loading platform lifting device - Google Patents

Description

  The present invention relates to a retractable cradle lifting and lowering device that supports an operation of loading and unloading a load on a loading platform of a vehicle.

  The load receiving device lifting / lowering device lifts and lowers the load receiving table between the height of the loading platform floor of the vehicle and the height of the ground, and assists in loading and unloading work on the loading platform of the vehicle. Among the load receiving platform lifting devices, there is a retractable type in which the load receiving platform is slid forward from the position at the time of cargo handling work and stored in the lower part of the vehicle frame (see Patent Document 1 and the like).

Japanese Patent Application Laid-Open No. 2005-233892

  By the way, in the said prior art, the load receiving stand is foldable, and when storing the load receiving stand, the front side member of the load receiving stand is folded over the upper part of the base side member. And after raising a load receiving stand to a predetermined position, a load receiving stand is advanced and it draws in the lower part of a vehicle frame. A U-shaped drop prevention member extends back and forth on the back side of the front side member (the upper surface of the load receiving stand in the retracted position). When the load receiving stand is pulled into the lower part of the car frame, The mating material on the guide rail side (the lower flange of the I-shaped guide rail) enters inside. In other words, by restricting the downward movement of the load cradle with the mating material on the guide rail side and the fall prevention member, the load cradle can be lowered unexpectedly during storage, which can occur due to leakage of pressure oil in the lift cylinder, etc. Is suppressed.

  However, the following problems exist in the above-described conventional technology.

  That is, in the storing operation, when the detector detects that the load receiving table has moved up to a predetermined position, the operation is switched to the pull-in operation (forward operation). The vertical range of movement of the load is not restricted, and the height of the load receiving platform during the pull-in operation is within the reaction time from the height detection by the detector until the operation is actually switched to the pull-in operation. Is determined by the height of the rise.

  At this time, the viscosity of the pressure oil in the cylinder varies depending on the temperature or the like, so that the lifting / lowering operation of the cargo cradle and the speed of forward / backward movement can vary depending on the temperature or the like. When the operating speed fluctuates, even when the same sequence is used, the height position of the receiving platform that moves forward changes when the receiving platform detects that the receiving platform has moved up to the specified position during the storage operation and switches to pull-in. The member may not enter smoothly.

  The present invention has been made in view of the above circumstances, and the retractable lifting / lowering of the retractable load receiving base capable of smoothly shifting the fall prevention member to the opposite state while suppressing the variation in the height position of the receiving load during the retracting operation during the storing operation. An object is to provide an apparatus.

In order to achieve the above object, a first aspect of the present invention is a retractable cradle lifting / lowering device for retracting and storing a cradle into a lower part of a vehicle frame, and a guide rail attached to the lower part of the vehicle frame, A travelable slider, an arm connecting the slider and the load receiving table, a lift cylinder for driving the arm to raise and lower the load receiving table, and driving the slider to move the load receiving table together with the slider to the guide A slide cylinder that moves along a rail, a fall prevention member having a first engagement member provided on the vehicle frame or the guide rail, and a second engagement member provided on the load receiving table, the lift cylinder, and the slide cylinder and a control unit for controlling, the control device, after the receiving platform, is raised to contact the guide rail, the moth Characterized in that to oppose the second engagement member to the first engagement member is pulled in a state in contact with the Doreru.

  According to a second invention, in the first invention, the control device raises the load receiving platform from a ground contact position to a set intermediate height lower than the height of the storage position, and the intermediate height. A first pulling operation of pulling the reached cargo receiving table to a lower intermediate position of the vehicle frame to an intermediate position set before the storing position, and raising the cargo receiving table reaching the intermediate position to the height of the storing position; A second ascending operation to press against the guide rail, and a second pulling-in of the load receiving table that has reached the height of the storage position to the storage position to make the second engagement member face the first engagement member. A pull-in operation is performed to store the consignment table.

  According to a third aspect of the present invention, in the second aspect of the present invention, a pressure sensor that detects that the load receiving table is pressed against the guide rail is provided, and the pressure sensor detects that the load receiving table is pressed against the guide rail. Then, the control device switches the operation of the load receiving table from the second ascending operation to the second retracting operation.

  According to a fourth invention, in the second or third invention, there is provided a hydraulic pump, a lift cylinder control valve for controlling a flow of pressure oil from the hydraulic pump to the lift cylinder, and a discharge pipe of the hydraulic pump. A main relief valve that regulates the maximum value of pressure oil, a sub-relief valve that regulates the maximum value of pressure oil in the discharge line to a value lower than the relief pressure of the main relief valve, and the pressure to the sub-relief valve A switching valve that communicates or shuts off the flow of oil, and during the storage operation of the load receiving platform, the control device opens the switching valve and executes the circuit of the lift cylinder when performing the second ascending operation. The maximum pressure is switched from the relief pressure by the main relief valve to the relief pressure by the sub relief valve.

  According to the present invention, it is possible to smoothly shift the fall prevention member to the facing state while suppressing variations in the height position of the load receiving table during the retracting operation during the storing operation.

It is a side view showing the whole structure of the vehicle carrying the retractable load receiving table raising / lowering device which concerns on one embodiment of this invention. It is a perspective view showing the detailed structure of the retractable receiving platform raising / lowering device which concerns on one embodiment of this invention, Comprising: The state which stored the receiving platform is represented. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a detailed structure of a retractable load receiving table lifting apparatus according to an embodiment of the present invention, showing a state in which the load receiving table is developed. It is an enlarged view of the rear end vicinity of the guide rail at the time of storage of the load receiving table of the retractable load receiving lift device according to the embodiment of the present invention. It is a hydraulic circuit diagram showing the example of 1 composition of the hydraulic drive unit with which the retractable load receiving device raising and lowering device concerning one embodiment of the present invention was equipped. It is a functional block diagram showing the example of 1 structure of the control apparatus with which the retractable load receiving stand raising / lowering device which concerns on one embodiment of this invention was equipped with the peripheral device. It is a flowchart showing the control procedure of the storing operation of the load receiving stand by the control apparatus with which the retractable receiving stand raising / lowering apparatus which concerns on one embodiment of this invention was equipped. It is the schematic diagram put together in the table | surface form about the relationship between the state of the load receiving stand in the storing operation | movement in the retractable load receiving stand raising / lowering apparatus which concerns on one embodiment of this invention, and on / off of an input-output signal.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a side view showing the overall structure of a vehicle equipped with a retractable load receiving device lifting apparatus according to an embodiment of the present invention. In the present specification, the left and right in FIG.

  The vehicle shown in FIG. 1 includes a vehicle frame 1, a driver's cab 2 provided in front of the vehicle frame 1, a cargo bed 3 mounted on the vehicle frame 1, and a retractable retractable load receiving table provided on the lower rear side of the vehicle frame 1. Elevating device 4 is provided. The retractable load receiving platform lifting device 4 folds the load receiving stand 5 and stores it in the lower side of the car frame 1 during traveling operation, for example, while loading work (loading and unloading work) on the load receiving platform 3 or the like. Is pulled back and deployed, and the work is supported by moving up and down between the floor surface height of the loading platform 3 and the ground height.

  FIGS. 2 and 3 are perspective views showing the detailed structure of the retractable load receiving table elevating device 4. FIG. 2 shows a state where the load receiving stand 5 is stored, and FIG. 3 shows a state where the load receiving stand 5 is expanded.

  As shown in FIGS. 2 and 3, the retractable load receiving device elevating device 4 includes the load receiving platform (platform) 5 on which a load is loaded, a slide drive unit 6 for moving the load receiving stand 5 and the like in the front-rear direction, An elevating drive unit 7 for elevating the load receiving platform 5 is provided.

  The slide drive section 6 is engaged and supported by a pair of left and right guide rails 8 attached to the lower rear side of the vehicle frame 1 so as to extend in the front-rear direction, and can run along the guide rails 8. Left and right sliders 9, connecting members 10 mounted on the left and right sliders 9, left and right bracket portions 11 provided outside the sliders 9 in the connecting members 10, and left and right support frames projecting behind the sliders 9. 13 (see FIG. 3), a support roller 12 provided at the front end of the support frame 13 to which the load receiving table 5 rolls when stored and unfolded, and the left and right sliders 9 together with the left and right sliders 9 along the guide rails 8 And left and right slide cylinders 14 to be moved. As the left and right slide cylinders 14 extend and retract, the slider 9 moves along the guide rail 8, and the connecting member 10, the bracket portion 11, the support frame 13, and the support roller 12 slide in the front-rear direction together with the slider 9. To do. At this time, the left and right guide rails 8 are provided with front and rear stoppers (not shown) for restricting the range of movement of the slider 9 in the front-rear direction and a position where the slider 9 contacts the rear stopper (hereinafter referred to as “rear end position”). ) And a set position (hereinafter referred to as “intermediate position”) between the rear end position of the rear end sensor 15 (see FIG. 6 to be described later) and the position in contact with the front stopper (hereinafter referred to as “storage position”). ]) Is provided with an intermediate sensor 16 (see FIG. 6 to be described later). For these sensors 15, 16, for example, proximity sensors or limit switches can be used.

  The elevating drive unit 7 has a first arm (tilt arm) 17 whose upper end is rotatably connected to the bracket 11, a front end is rotatable to the first arm 17, and a rear end is rotatable to the load receiving platform 5. A second arm (lift arm) 18 connected to the front end, a third arm (compression arm) 19 whose front end is pivotally connected to the bracket portion 11 and rear end to the load receiving platform 5, respectively, and the rod side is first A pair of left and right lift cylinders 20 each having a bottom side rotatably connected to a second arm 18 are provided at the lower end of one arm 17. The second arm 18 and the third arm 19 form a parallel link that connects the load receiving platform 5 to the slider 9 so as to be movable up and down, and the parallel link is driven to rotate up and down as the lift cylinder 20 extends and contracts. Thus, the load receiving platform 5 moves up and down while maintaining a horizontal posture.

  The load receiving platform 5 includes a load receiving platform base end 21 supported by the elevating drive unit 7, a load receiving base main body 23 rotatably connected to the load receiving base base end 21 via a hinge 22, and a load receiving base main body. A load receiving table distal end portion 25 rotatably connected to the portion 23 via a hinge 24 and a pad 80 described later are provided. Both ends of the hinge 22 are connected to the vicinity of the upper surfaces of the load receiving base end 21 and the load receiving main body 23 via pins (not shown), respectively, and the load receiving base main body with respect to the load receiving base 21 The rotating mechanism of the part 23 has a double joint structure through the hinge 22. Similarly, both ends of the hinge 24 are pivotally connected to the vicinity of the upper surfaces of the load receiving base body portion 23 and the load receiving tip end portion 25 via pins (not shown), respectively. The turning mechanism of the distal end portion 25 has a double joint structure through the hinge 24. The load receiving table main body 23 and the load receiving table distal end 25 are each turned upward and folded from the unfolded state.

  At this time, although not shown in FIGS. 2 and 3, the hinge 22 connecting the load receiving base end 21 and the load receiving main body 23 has an intermediate height between the ground contact position and the storage position (hereinafter “ A gate sensor 56 (see FIG. 6) for detecting the attitude (opening degree) of the receiving platform 5 during the storing operation is provided as a value serving as a basis for determining whether or not it is at the “intermediate height”. As the gate sensor 56, an angle sensor that detects an angle of the hinge 22 with respect to the load receiving base end portion 21 can be used.

  As described above, since the hinge 22 has a double joint structure, when the load receiving base body portion 23 is folded on the load receiving base end portion 21, the load receiving base body portion 23 is rotated 90 degrees with respect to the hinge 22, The hinge 22 is constrained by the load receiving base body 23 and starts to rotate with respect to the load receiving base 21, and finally the load receiving surfaces of the load receiving base 23 and the load receiving base 21 face each other. When the load receiving platform 5 is stored after the work, the lift arm 18 is raised with the load receiving platform tip 25 and the load receiving table main body 23 folded and leaning against the support roller 12 as will be described later. The rising angle of the hinge 22 with respect to the base end portion 21 (angle R of the hinge 22 with respect to the horizontal (see FIG. 3)) does not reach 90 degrees. The angle of the hinge 22 relative to the load receiving base end 21 when the load receiving base 5 is deployed is 0 (zero), and the load receiving base base 21 when the load receiving main body 23 is leaned against the support roller 12 at the ground contact position. When the angle of the hinge 22 with respect to is α (0 <α <90 °), the gate sensor 56 is configured such that the angle R of the hinge 22 with respect to the load receiving base end 21 is a set angle β (α <β ≦ 90 °). Is set to output a detection signal. The set angle β is, for example, the angle R of the hinge 22 when the load receiving platform 5 starts to rise from the ground contact position and reaches the above-described intermediate height during the storing operation, and when the angle R = the set angle β, the load receiving platform 5 is Lift from the ground.

  Further, a hydraulic drive device (power unit) 26 for driving the slide cylinder 14 and the lift cylinder 20 is provided at the left end portion of the bracket portion 11 of the slide drive portion 6, and the retractable load receiving device elevating device 4 is provided at the right end portion. A loading platform outer side operation device 27 (only a switch box is shown in FIGS. 2 and 3 and will be described in detail later) is provided.

  FIG. 4 is an enlarged view of the vicinity of the rear end of the guide rail 8 at the time of storing the cargo cradle.

  FIG. 4 shows the vicinity of the rear end of the left guide rail 8. As shown in this figure, the guide rail 8 and the cargo cradle 5 are provided with a fall prevention member 75 that suppresses an unexpected dropping operation of the cargo cradle 5. The fall prevention member 75 includes a first engagement member 76 attached to the side surface of the guide rail 8 with a bolt or the like, and a second engagement attached to the back surface (the surface facing upward during storage) of the load receiving table main body 23 with a bolt or the like. And a joint member 77. The first engagement member 76 has a flange 78 extending toward the second engagement member 77 side (right side in FIG. 4), and the second engagement member 77 is on the first engagement member 76 side (in FIG. 4). It has a flange 79 extending toward the left side. The second engagement member 77 moves with the back-and-forth movement of the load receiving platform 5 during the storage operation. In the present specification, the state in which the flanges 78 and 79 are opposed to each other vertically is referred to as “opposing state”, and the state in which the second engagement member 77 is moved rearward and the positions of the flanges 78 and 79 are displaced is referred to as “non-opposing state”. To do. In the opposed state, even if pressure oil leaks in the lift cylinder 20, the flange 79 comes into contact with and engages with the flange 78, so that the descent of the load receiving platform 5 is suppressed. If it is not necessary to consider the manufacturing error of the retractable cargo receiver lifting device 4, the gap between the opposing flanges 78, 79 is secured to the extent that they do not rub when the flange 79 moves relative to the flange 78. However, in practice, it is preferable to secure a larger value in consideration of manufacturing errors.

  In addition, as described above, the pad 80 is provided on the receiving platform 5. The pad 80 is provided on the back surface (the surface facing upward when stored) of the cradle body 23, and is made of, for example, resin. The pad 80 comes into contact with the lower surface of the guide rail 8 when the load receiving platform 5 is at the height of the storage position. It is sufficient if the contact surface of the pad 80 with respect to the guide rail 8 is secured to such an extent that the contact surface pressure does not become excessively high, and it is not necessary to take it wide. The thickness of the pad 80 is set such that the above-described gap is secured between the opposing flanges 78 and 79 in a state where the pad 80 is in contact with the guide rail 8.

  Protrusions 8 a and 8 b that guide the slider 9 extend in the extending direction of the guide rail 8 on the upper and lower surfaces of the guide rail 8. The protrusions 8a and 8b have a triangular shape with a cross-sectional width narrowing toward the tip, and a groove (not shown) formed in a V shape is formed in the pad 80 in accordance with the lower protrusion 8b. Has been. That is, when the pad 80 hits the guide rail 8, the protrusion 8 b on the lower side of the guide rail 8 enters the groove of the pad 80 to restrain the movement of the load receiving platform 5 in the left-right direction, and the groove of the pad 80. The projection 8b functions as a positioning guide.

  FIG. 5 is a hydraulic circuit diagram showing a configuration example of the hydraulic drive device 26.

  In FIG. 5, the hydraulic drive device 26 includes an electric motor 28, a hydraulic pump 29 driven by the electric motor 28, an oil tank 30 provided on the suction side of the hydraulic pump 29, and a discharge pipe 29 a of the hydraulic pump 29. Of the pressure oil supply passage 31 for supplying the pressure oil to the lift cylinder 20, the control valve 32 for raising operation for communicating or blocking the flow of the pressure oil supply passage 31, and the control valve 32 for raising operation in the pressure oil supply passage 31. A pressure oil return passage 33 that branches from the downstream side and is connected to the oil tank 30, a lower operation control valve 34 that communicates or blocks the flow of the pressure oil return passage 33, and a lower operation control valve 34. A flow control valve 35, a main relief valve 36 for defining the maximum discharge pressure of the hydraulic pump 29, and a conductor relay interposed between the electric motor 28 and a battery (not shown). And a 7. In the present embodiment, the raising operation control valve 32 and the lowering operation control valve 34 constitute a lift cylinder control valve that controls the flow of pressure oil from the hydraulic pump 29 to the lift cylinder 20.

  For example, during the lifting operation of the cargo receiving platform 5 during the cargo handling operation or the storage operation, the coil 37a of the conductor relay 37 is energized according to a command signal output from the control device 45 in response to an operation signal from the wireless operation device 46 or the like described later. Thus, the normally open contact point 37b is closed, and the electric motor 28 is supplied with power from the battery via the contact point 37b to drive the hydraulic pump 29. At the same time, a drive command signal is input to the solenoid portion 32a of the raising operation control valve 32, and the raising operation control valve 32 is switched to the communication position on the left side in FIG. At this time, since the lowering control valve 34 is at the lower cutoff position in FIG. 5, the pressure oil from the hydraulic pump 29 is supplied to the bottom side of the lift cylinder 20 via the pressure oil supply passage 31. Elongates and the cradle 5 rises.

  On the other hand, when the load receiving platform 5 is lowered in the cargo handling operation or the unfolding operation, the contact 37b is opened according to a command signal output from the control device 45 in response to an operation signal from the wireless operation device 46 or the like, and the electric motor 28 and the hydraulic pump 29 are opened. Is stopped and the raising operation control valve 32 is in the blocking position on the right side in FIG. At the same time, a drive command signal is input to the solenoid portion 34a of the lowering control valve 34, the lowering control valve 34 is switched to the upper communication position in FIG. 5, and the bottom side of the lift cylinder 20 passes through the pressure oil return passage 33. Through the oil tank 30 and the load receiving platform 5 is lowered by its own weight.

  The hydraulic drive device 26 also includes a pressure oil supply passage 38 branched from the discharge pipe 29 a of the hydraulic pump 29 and connected to the rod side of the slide cylinder 14, a throttle valve 39 provided in the pressure oil supply passage 38, and a check. A valve 40, a pressure oil supply passage 41 branched from the pressure oil supply passage 38 and connected to the bottom side of the slide cylinder 14, a reverse operation control valve 42 for communicating or blocking the flow of the pressure oil supply passage 41, and a reverse movement A pressure oil return passage 43 branched from the pressure oil supply passage 41 on the downstream side of the operation control valve 42 and in contact with the oil tank 30, and a forward operation control valve 44 for communicating or blocking the flow of the pressure oil return passage 43; It has.

  For example, during the sliding operation of the cargo receiving platform 5 in the unfolding operation, the contact 37b of the conductor relay 37 is closed according to a command signal output from the control device 45 in response to an operation signal from a wireless operation device 46 or the like described later, and the electric motor 28. Then, the hydraulic pump 29 is driven, and at the same time, a drive command signal is input to the solenoid part 42a of the reverse operation control valve 42, and the reverse operation control valve 42 is switched to the upper communication position in FIG. At this time, since the forward operation control valve 44 is in the lower cutoff position in FIG. 5, the pressure oil from the hydraulic pump 29 is supplied to the bottom side of the slide cylinder 14 via the pressure oil supply passage 41, The slide cylinder 14 is driven in the extending direction due to the pressure receiving area difference, and the load receiving platform 5 and the like slide rearward.

  On the other hand, at the time of the sliding operation of the load receiving tray 5 in the storing operation, the contact 37b of the conductor relay 37 is closed according to a command signal output from the control device 45 in response to an operation signal from the wireless operation device 46 and the like which will be described later. Then, the hydraulic pump 29 is driven, and simultaneously, a drive command signal is input to the solenoid portion 44a of the forward operation control valve 44, and the forward operation control valve 44 is switched to the upper communication position in FIG. At this time, since the reverse operation control valve 42 is in the lower cutoff position in FIG. 5, the pressure oil from the hydraulic pump 29 is supplied to the rod side of the slide cylinder 14 via the pressure oil supply passage 38. The pressure oil from the bottom side flows out to the oil tank 30 through the pressure oil return passage 43. As a result, the slide cylinder 14 is driven in the contraction direction, and the load receiving platform 5 and the like slide forward.

  In order to raise and lower the load receiving platform 5 with the slider 9 in the rear end position, while the lift cylinder 20 is extended, the reverse operation control valve 42 is switched to the communication position and the slider 9 is used as the rear stopper described above. It can also be configured to press. Further, the hydraulic pump 29 can be driven even when the load receiving platform 5 is lowered to supply pressure oil to the bottom side of the reverse operation control valve 42 so as to bias the slider 9 to the rear end position. . Further, the forward movement control valve 44 can be instantaneously switched to the communication position when the load receiving platform 5 is slid rearward, and the slide cylinder 14 can be depressurized.

  In the present embodiment, there is a bypass passage 71 branched from the discharge pipe 29 a between the throttle valves 39 and connected to the pressure oil return passage 43, and the sub-relief valve 73 is provided in the bypass passage 71. And a switching valve 72 are provided. The switching position of the switching valve 72 is switched to a communication position (upper position in the figure) or a blocking position (lower position in the figure) according to a drive signal to the solenoid driving unit 72a, and the sub relief valve 73 is switched according to the switching position. Communicate or block the flow of pressure oil to The switching valve 72 is provided on the upstream side of the sub relief valve 73, but may be provided on the downstream side. The sub-relief valve 73 has a relief pressure (for example, about 6 MPa) set lower than the relief pressure (for example, about 20 MPa) of the main relief valve 36, and the switching valve 72 is switched to the communication position to enter the discharge pipe 29 a. When the connection is established, the maximum value of the pressure oil in the discharge pipe 29 a is regulated to a value lower than the relief pressure of the main relief valve 36.

  Further, a pressure sensor 74 is provided in the discharge pipe 29 a of the hydraulic pump 29 as a pressure sensor that detects that the pad 80 of the load receiving platform 5 is pressed against the guide rail 8. That is, when the lift cylinder 20 extends and the load receiving platform 5 comes into contact with the pad 80 of the guide rail 8, the pressure in the discharge pipe 29a rises. Therefore, a threshold value (set value) is set for the detection value of the pressure sensor 74. If the detected value exceeds the threshold value, it can be determined that the load receiving platform 5 is in contact with the guide rail 8.

  FIG. 6 is a functional block diagram showing an example of the configuration of the control device provided in the retractable cargo receiving table lifting device 4 together with peripheral devices.

  In FIG. 6, a rear end sensor 15 for detecting whether or not the load receiving base 5 is in the rear end position, a gate sensor 56 for detecting that the receiving operation of the load receiving base 5 is started, and the folded load receiving base 5 slide. An intermediate sensor 16 that detects whether or not it is in a retractable storage position, a loading platform outer operation device 27 that outputs an operation signal to the retractable loading platform elevating device 4 by wire, and a control provided on the vehicle side (or in the power unit 26) A device 45 and a portable wireless operation device (remote control) 46 that wirelessly outputs an operation signal for the retractable cargo receiver lifting device 4 are provided. The control device 45 is connected to a power source (battery) 57 of the retractable cargo receiver lifting device 4 via a power switch 58, and the power switch 58 switches on / off of the power source of the control device 45. The power switch 58 can be installed in the cab 2 of the vehicle or in the power unit 26, for example.

  The loading platform outer side operation device 27 is, for example, of a pendant operation type including a push button type raising operation switch 47A and a lowering operation switch 47B, and an operation signal corresponding to the operation of the raising operation switch 47A or the lowering operation switch 47B. The data is output to the control device 45 via a cable or the like.

  The wireless operation device 46 generates push button type raising operation switch 48A, lowering operation switch 48B, power switch 48C, and serial data such as ON / OFF state of the operation switch 48A or 48B, and uses this serial data as a radio signal. And a transmission unit 49 for transmission. Of course, it can be stored in an arbitrary place such as in the cab 2 or the loading platform 3.

  The control device 45 includes an input unit 50 for inputting detection signals from the rear end sensor 15, the intermediate sensor 16, the gate sensor 56 and the pressure sensor 74, and an operation signal from the loading platform outer operation device 27, and a wireless operation from the wireless operation device 46. A receiving unit (input unit) 51 that receives an operation signal, a storage unit (memory) 52 that stores a control program (for example, a program based on sequence control, timer control, and the like) and a control threshold value, and the storage unit 52 store the operation signal. An arithmetic processing unit (CPU) 53 that executes arithmetic processing according to the control program and generates a command signal or the like for instructing the operation of the cylinders 14 and 20, and the command signal generated by the arithmetic unit 53 for each control valve 32, 34, 42. , 44, 72, and an output unit 54 for outputting to the conductor relay 37 as appropriate, and the solenoid units 32a, 34a, 42a, 44a, 72a.

  Next, the operation of the retractable load receiving device lifting device 4 will be described.

  For example, when using the load receiving stand 5 stored in the lower part of the car frame 1, the power switch 58 of the control device 45 is turned on, and the lowering operation switch 48B of the wireless operation device 46 or the lowering operation switch 47B of the outer operation device 27 of the loading platform is turned on. If pressed, while the switch is being operated, an extension command for the slide cylinder 14 is issued via the control device 45, and the load receiving platform 5 moves rearward from the storage position. When the rear end sensor 15 detects that the load receiving platform 5 has been pulled out to the rear end position, when the switch 48B or 47B is further pressed, the command signal from the control device 45 is switched to the degeneration command of the lift cylinder 20, The load receiving platform 5 is lowered to the ground contact position. When the cargo cradle 5 is lowered to the grounding position, the cargo cradle 5 is unfolded and the cargo cradle 5 is moved up and down by appropriately operating the raising operation switch and the lowering operation switch of the wireless operation device 46 or the loading platform outer operation device 27. It can be used to support work.

  Note that the unfolding operation is a two-stage operation of pulling out the load receiving platform 5 → lowering the load receiving platform 5, but it may be the reverse operation of the storage operation described below.

  FIG. 7 is a flow chart showing the control procedure of the storage operation of the cargo cradle 5 by the control device 45, and FIG. It is the summarized schematic diagram.

  As shown in these drawings, during the retracting operation of the retractable load receiving device elevating device 4, the control device 45 retracts the load receiving stand 5 in contact with the guide rail 8 to bring the second engagement member 79 into the first engaging member 79. The procedure of making it oppose to the engaging member 78 is performed. Specifically, in the case of the present embodiment, a first ascending operation for raising the load receiving platform 5 from the ground contact position to an intermediate height lower than the height of the storage position, and the load receiving platform 5 that has reached the intermediate height in the storage position. A first pull-in operation that pulls the vehicle frame 1 to the lower intermediate position, a second lift operation that raises the load receiving platform 5 that has reached the intermediate position to the height of the storage position, and presses it against the guide rail 8; A second retracting operation is performed in which the load receiving platform 5 that has reached the height of the position is retracted to the retracted position and the fall prevention member 75 is shifted to the facing state. Details are as follows.

<First lifting operation>
Here, the procedure of steps 101 to 104 in FIG. 7 and the illustrations of “grounding” and “first rise” in the upper two stages in FIG. 8 are referred to together.

  For example, when the cargo receiving platform 5 is stored in the lower part of the car frame 1 after the cargo handling operation is completed, first, the cargo receiving platform 5 is folded at the ground contact position and leaned against the support roller 12 (step 101), and the lifting operation switch 47A of the operating device 27 or 46 or Press 48A. The control device 45 determines whether or not the operation signal of the raising operation switch 47A or 48A has been input (step 102). When an operation signal is input, the conductor relay 37 (see FIG. 5) is energized to drive the hydraulic pump 29, and an extension command for the lift cylinder 20 is output to raise the load receiving platform 5 (step 103). If there is no operation signal input, step 102 is repeated to wait for the operation signal input. While the load receiving platform 5 is being raised, it is determined based on the signal from the gate sensor 56 whether or not the angle of the load receiving platform 5 (the hinge 22) has reached the set angle β described above (step 104). While the signal of the gate sensor 56 is OFF and the angle of the load receiving platform 5 does not reach β, the procedure of steps 102 to 104 is repeated, and the load receiving platform 5 is raised only while the raising operation switch 47A or 48A is operated. Stop when the operation is released.

<First pull-in operation>
Here, the procedure of steps 104 to 107 in FIG. 7 and the illustration of “first pull-in” in the third row in FIG. 8 are referred to together.

  When the detection signal from the gate sensor 56 is input while the load receiving table 3 is raised and it is recognized in step 104 that the receiving operation is being performed and the load receiving table 5 has reached the intermediate height, the control device 45 further performs a raising operation. It is determined whether or not an operation signal for the switch 47A or 48A has been input (step 105). If an operation signal has been input, a degeneration command for the slide cylinder 14 is output to advance the slider 9 together with the load receiving platform 5 (step 105). 106) If there is no operation signal input, step 105 is repeated to wait for the operation signal input. While the load receiving platform 5 is moving forward, it is determined based on the signal from the intermediate sensor 16 whether or not the slider 9 has reached the intermediate position (step 107). While the signal of the intermediate sensor 16 is OFF and the slider 9 does not reach the intermediate position, the procedure of steps 105 to 107 is repeated, and the slider 9 is advanced only while the raising operation switch 47A or 48A is operated, and the operation is released. If it is, stop it.

<Second ascent action>
Here, the procedure of steps 107-111 in FIG. 7 and the illustration of “second rise” in the fourth row in FIG. 8 are referred to together.

  When the detection signal from the intermediate sensor 16 is input while the slider 9 moves forward and it is recognized in step 107 that the slider 9 has reached the intermediate position, the control device 45 stops the slide cylinder 14 and switches the switching valve 72. Is switched to the communication position to switch the relief pressure of the hydraulic circuit to a low relief pressure by the sub relief valve 73 (step 108). Thereafter, it is determined whether or not an operation signal for the raising operation switch 47A or 48A has been input (step 109). If an operation signal is input, an extension command for the lift cylinder 20 is output to raise the load receiving platform 5 ( Step 110) If no operation signal is input, Step 109 is repeated to wait for the input of the operation signal. When the re-raising of the load receiving platform 5 is started, the relief pressure is not strictly reduced to the relief pressure by the sub-relief valve 73 at the start of raising from the intermediate height. It is only necessary to switch to a state where can be operated. Alternatively, the re-lifting of the load receiving platform 5 may be delayed from the switching of the relief valve due to a timing error, but it is sufficient that the sub-relief valve 73 can be operated before the load receiving platform 5 is lifted up. .

  While the load receiving platform 5 is rising, it is determined based on the signal from the pressure sensor 74 whether or not the load receiving platform 5 has reached the height of the storage position (step 111). While the signal of the pressure sensor 74 is OFF and the load receiving platform 5 does not reach the storage position height, the procedure of steps 109 to 111 is repeated, and the load receiving platform 5 is raised only while the raising operation switch 47A or 48A is operated. If the operation is released, stop the operation.

<Second pull-in operation>
Here, the procedure of steps 111 to 116 in FIG. 7 and the illustration of “second pull-in” at the bottom in FIG. 8 are referred to together.

  When the detection signal from the pressure sensor 74 is input while the load receiving platform 5 is raised and it is recognized in step 111 that the load receiving platform 5 has reached the height of the storage position, the control device 45 stops the lift cylinder 20. At the same time, the switching valve 72 is switched to the cutoff position to restore the relief pressure of the hydraulic circuit to the relief pressure by the main relief valve 36 (step 112).

  Thereafter, it is determined whether or not an operation signal for the raising operation switch 47A or 48A has been input (step 113). If an operation signal has been input, a contraction command for the slide cylinder 14 is output and the slider 9 is advanced (step). 114) If no operation signal is input, step 113 is repeated to wait for the input of the operation signal. While the load receiving platform 5 is moving forward, it is determined whether or not the operation of the raising operation switch 47A or 48A is stopped (step 115), and the procedure of steps 114 and 115 is repeated while the operation signal is being input. 14 continues to feed pressure oil to the rod side, for example, when the load receiving platform 5 has completely moved forward (has reached the retracted position) and the operator has released his / her finger from the raising operation switch 47A or 48A, the forward movement operation of the load receiving platform 5 (slide cylinder) 14 is stopped (supply of pressure oil to the rod side) (step 116).

  In addition, in the process of the 2nd drawing-in operation | movement of this load receiving stand 5, when the load receiving stand 5 reaches storage height, the fall prevention member 75 will be in a facing state from a non-opposing state.

<End operation>
Here, the procedure of steps 117 to 118 in FIG. 7 is referred to.

  After the second forward stop of the receiving platform 5, it is determined whether or not the raising operation switch 47A or 48A is operated before the control device 45 is turned off (step 117). The procedure is returned and pressure oil is supplied to the rod side of the slide cylinder 14. If there is no operation, the hydraulic pump 29 is stopped to determine whether or not the power is turned off (step 118). If not, the procedure returns to step 117 and waits. Exit.

  As described above, according to the present embodiment, as described above, when the load receiving platform 5 is moved to the storage position, the load receiving platform 5 is pressed against the guide rail 8 by performing the second raising operation. There is no backlash between the load receiving platform 5 and the guide rail 8 at the stage where the fall prevention member 75 is shifted to the facing state. Therefore, it is not affected by fluctuations in the operating speed of the cylinders 14 and 20 due to the viscosity of the pressure oil, so that variations in the height position of the load receiving platform 5 during the second pull-in operation can be suppressed during the storing operation, and the storing position can be accurately performed. The fall prevention member 75 can be smoothly shifted to the facing state by advancing the load receiving platform 5 at a height of. Furthermore, since the variation in the height position of the load receiving platform 5 when the fall prevention member 75 is shifted to the opposed state can be suppressed, the gap between the flanges 78 and 79 of the fall prevention member 75 can be set small, and the lift The descending width of the load receiving tray 5 that is allowed when the hydraulic oil leaks from the cylinder 20 can be suppressed to an extremely small distance.

  In particular, in the present embodiment, since the pressure sensor 74 is used to recognize that the load receiving platform 5 is in contact with the guide rail 8, the final second pull-in operation is performed, so that the height of the storage position is more reliably determined. The cargo cradle 5 can be moved forward.

  In addition, when the relief pressure of the hydraulic circuit is lowered to the low relief pressure by the sub relief valve 73 during the second ascending operation, the pressing force acting between the load receiving platform 5 and the guide rail 8 is excessive. In the second forward movement, the pad 80 can be slid lightly on the guide rail 8 to advance the load receiving platform 5. Moreover, since the contact pressure with respect to the guide rail 8 of the load receiving pedestal 5 can be suppressed, the stress which acts on the guide rail 8 and the load receiving pedestal 5 can fully be suppressed, and the storing operation of the load receiving pedestal 5 is repeated in normal operation. Even if the operation is performed, the load on the components of the apparatus is small, and shortening of the life of the apparatus can be suppressed.

  Note that no precision is required for the “intermediate height” for switching the operation from the first ascending operation to the first advancing operation and the “intermediate position” for switching the operation from the first ascending operation to the second ascending operation. Therefore, there is no problem even if variations in the height direction or the front-rear direction position of the operation switching occur due to fluctuations in the operation speed of the cylinders 14 and 20. In view of this, since it is sufficient that the load receiving platform 5 is finally in contact with the guide rail 8 during the second pull-in operation, the sensors 15, 16, 56, and 74 are arranged as in the present embodiment. The first ascending operation → the first pulling operation → the second ascending operation → the second pulling operation is not limited to the configuration of switching between the operation and the movement from the grounding position without using a sensor. It can also be set as the structure which moves the goods receiving stand 5 to a storing position. Even in such a configuration, the first and second ascents are considered in consideration of variations in the operating speeds of the cylinders 14 and 20 that can be generated to ensure that the load receiving platform 5 comes into contact with the guide rail 8 in the second ascending operation. What is necessary is just to set the increase width of operation | movement large. Even if the increase width is large, the contact pressure between the guide rail 8 and the load receiving platform 5 does not increase more than necessary by switching to the relief pressure by the sub relief valve 73. In this case, the manufacturing cost can be reduced in addition to simplification of the hardware configuration by reducing the number of sensors.

  Further, for example, instead of suppressing the variation in the height position of the load receiving table when the fall prevention member is shifted to the facing state, a configuration in which some kind of movable mechanism is added to the fall prevention member to allow the variation is also conceivable. When the movable mechanism is added, the operation quality of the movable mechanism may deteriorate and the operation may not be smoothly performed when rust or wear occurs with long-term use. On the other hand, in the case of the present embodiment, the fall prevention member 75 is a fixed member having a simple configuration, and therefore the operation of the fall prevention member 75 according to the secular change of the fall prevention member 75 itself, for example, facing state or non-facing state. There is no such a problem that the transition operation to is not performed smoothly.

  In the present embodiment, the case where the cargo receiving platform 5 is stored in the procedure of the first ascending operation → the first retracting operation → the second ascending operation → the second retracting operation has been described as an example. The essence of the present invention is to retract the load receiving base 5 in contact with the guide rail 8 so that the second engaging member 79 faces the first engaging member 78, and the load receiving base 5 contacts the guide rail 8. There is no particular limitation on the procedure up to (the operation path of the cargo receiving platform 5). As an example, the load receiving platform 5 is first pulled forward for a short distance (for example, to the position where the pad 80 comes into contact with the vicinity of the rear end of the guide rail 8 if it is lifted as it is), and then the load receiving platform 5 is raised and guided. It is also possible to employ a retracting → lift → retracting storage operation in which the rail 8 is brought into contact with and further retracted to the retracted position. In this case, in order to facilitate the pull-in operation in a state where the load receiving platform 5 is grounded, a roller can be provided on the grounding portion of the load receiving platform 5 as necessary. Alternatively, the load receiving platform 5 is first pulled from the ground contact position by a minute distance and then raised to an intermediate height, and then pulled up to the intermediate position and then lifted to contact the guide rail 8. The load receiving platform is in contact with the guide rail 8. It is also possible to adopt a storage operation of drawing-in, ascending, drawing-in, ascending, and drawing-in, in which 5 is finally pulled to the storage position. Further, it is possible to perform a storing operation in which a pulling operation or a descending operation is incorporated in the middle if necessary. Also, various setting changes are allowed for the strokes of the pull-in operation and the ascending operation from the ground contact position to the storage position in the initial state of the storage operation. For example, when the ascending and retracting operations are repeated many times (for example, three times or more), the strokes of the ascending operations and the strokes of the retracting operations can be set at equal distances or can be set irregularly.

  Further, in the present embodiment, the case where the retractable load receiving device lifting device for storing the load receiving device in the lower part of the vehicle frame is described as an example of application, but this type of retractable load receiving device lifting device includes: In addition to the retracted posture stored in the lower part of the vehicle frame, there is a device that can select the retracted posture in which the load receiving stand is raised at the rear of the load carrier. This embodiment can be applied when storing the load receiving table in the lower part of the vehicle frame even if it is a retractable load receiving device lifting / lowering device of a kind that adopts such a plurality of storage postures. Can be obtained.

4 Retractable load receiving device lifting device 5 Load receiving table 8 Guide rail 9 Slider 14 Slide cylinder 17 First arm (arm)
18 Second arm (arm)
19 Third arm (arm)
20 Lift cylinder 29 Hydraulic pump 32 Control valve for lifting operation (control valve for lift cylinder)
34 Control valve for lowering operation (control valve for lift cylinder)
36 Main relief valve 45 Control device 72 Switching valve 73 Sub relief valve 74 Pressure sensor (pressing sensor)
75 Fall prevention member

Claims (4)

In the retractable load receiving device lifting device for retracting and storing the load receiving table in the lower part of the car frame,
A guide rail attached to the lower part of the vehicle frame;
A slider that can travel along this guide rail;
An arm connecting the slider and the load receiving table;
A lift cylinder that drives the arm to raise and lower the load receiving table;
A slide cylinder that drives the slider to move the load receiving table along with the slider along the guide rail;
A fall prevention member having a first engagement member provided on the vehicle frame or the guide rail and a second engagement member provided on the load receiving table;
A control device for controlling the lift cylinder and the slide cylinder;
The control device raises the load receiving platform until it comes into contact with the guide rail, and then pulls it in a state of being in contact with the guide rail so that the second engagement member faces the first engagement member. Retractable cargo receiving platform lifting device. The retractable load receiving device lifting apparatus according to claim 1,
The controller is
A first raising operation for raising the load receiving platform from a ground contact position to an intermediate height set lower than the height of the storage position;
A first pull-in operation of pulling the load receiving table that has reached the intermediate height into the lower part of the vehicle frame to an intermediate position set in front of the storage position;
A second ascending operation for raising the load receiving table that has reached the intermediate position to the height of the retracted position and pressing it against the guide rail;
The load receiving table that has reached the height of the storage position is retracted to the storage position, and the second engaging member is made to face the first engaging member, and the load receiving table is stored. A retractable cradle lifting device characterized by that. The retractable load receiving device lifting apparatus according to claim 2,
A pressure sensor for detecting that the load receiving table is pressed against the guide rail;
When it is detected by the pressing sensor that the load receiving table is pressed against the guide rail, the control device switches the operation of the load receiving table from the second ascending operation to the second retracting operation. Retractable cradle lifting device. The retractable cradle lifting device according to claim 2 or 3,
A hydraulic pump;
A lift cylinder control valve for controlling the flow of pressure oil from the hydraulic pump to the lift cylinder;
A main relief valve that regulates the maximum value of pressure oil in the discharge line of the hydraulic pump;
A sub-relief valve that regulates the maximum value of pressure oil in the discharge pipe to a value lower than the relief pressure of the main relief valve;
A switching valve for communicating or blocking the flow of pressure oil to the sub-relief valve;
At the time of storing operation of the consignment table, the control device
The retractable valve is configured to open the switching valve to switch the maximum pressure of the lift cylinder circuit from the relief pressure by the main relief valve to the relief pressure by the sub-relief valve when the second raising operation is performed. Loading platform lifting device.

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