JP5642478B2 - Loading platform lifting device - Google Patents

Description

  The present invention relates to a loading platform lifting / lowering device that supports loading and unloading work of a load on a loading platform of a vehicle.

  The load receiving platform lifting / lowering device lifts and lowers the load receiving platform in the vicinity of the vehicle loading platform entrance, and supports loading and unloading work of luggage and workers on the loading platform of the vehicle. Among these, there is a type in which a load receiving platform is connected to a base attached to a vehicle via an arm, and the load receiving platform is moved up and down by rotating the arm up and down with respect to the base (see Patent Document 1). The load receiving platform elevating device of the same document is configured to rotate the arm up and down by a single-acting lift cylinder having an oil chamber only on the bottom side. By supplying hydraulic oil to the oil chamber, the lift cylinder is extended to receive the load. When raising the platform while lowering the loading platform, the lift cylinder is contracted by applying its own weight to the loading platform, arm, etc. by connecting the oil chamber to the tank.

JP 2009-202667 A

  The area in which the vehicle equipped with the loading platform elevating device can operate is wide, and it may be used in a cold area or a warm area. Even in the same region, the temperature can fluctuate greatly depending on the time and time zone. When the temperature of the operating environment varies in this way, the viscosity of the hydraulic oil that is the working medium of the lift cylinder also varies. Further, when the load receiving device lifting / lowering device is continuously operated, the temperature of the hydraulic oil rises and the viscosity decreases. And when a single-acting lift cylinder is used like the load receiving table lifting device of the above-mentioned Patent Document 1, the flow rate of the hydraulic oil pushed out from the oil chamber is affected by the viscosity change. The descent speed can vary.

  On the other hand, if a double-acting lift cylinder is used, not only the ascending speed of the load receiving platform but also the descending speed can be controlled by the hydraulic oil supply flow rate. Speed can be stabilized.

  However, when the weight of the load to be loaded is large, the vehicle is greatly depressed. That is, the height position of the loading platform of the vehicle with respect to the ground can change depending on the weight of the loaded luggage. For this reason, the ground on which the cradle is grounded is not necessarily in a certain positional relationship with the vehicle. Therefore, when the load receiving platform is lowered by the positive operation of the double-acting lift cylinder, if the load receiving platform is grounded before the cylinder operating amount reaches the specified amount, the specified operating amount will be maintained even after touching. The descending operation of the receiving platform can be continued until In this case, the load receiving platform lifting device acts in the direction of pushing the ground and lifting the rear part of the vehicle, and in extreme cases, the load of the vehicle is applied to the arm or the like and the load receiving platform lifting device may be damaged.

  The present invention has been made in view of the above circumstances, and is capable of moving the load receiving table up and down at a stable speed, and suppressing the contact pressure between the load receiving table and the ground to suppress self damage. The purpose is to provide.

To achieve the above object, according to a first aspect of the present invention, there is provided a load receiving platform lifting / lowering device for supporting loading and unloading of a load on a vehicle loading platform, a base unit attached to the vehicle, an arm unit coupled to the base unit, A load receiving base connected to the arm unit, a double-acting lift driving device that drives the arm unit to raise and lower the load receiving base, a grounding sensor that detects that the load receiving base is grounded, and the lift driving device A hydraulic pump that supplies hydraulic oil to the hydraulic pump, a tilt drive device that operates with hydraulic oil from the hydraulic pump to tilt and displace the load receiving table with respect to the arm unit, and a discharge pipe and a tank of the hydraulic pump. a low pressure relief pipe which connects the low-pressure relief valve provided on the low-pressure relief conduit, and switching valve provided in the low-pressure relief conduit, the lift Control means for driving the tilt drive device together with the lift drive device to deploy the load stand when the detection signal from the grounding sensor is input while driving the moving device to lower the load support table, control means is characterized between, and Turkey to open the switching valve detection signal from the ground sensor when the receiving platform of the lowering operation is inputted.

A second invention is characterized in that, in the first invention, the relief pressure of the low pressure relief valve is lower than the relief pressure of the relief valve for circuit protection provided in the discharge pipe of the hydraulic pump. To do.

According to a third aspect of the present invention, in the first or second aspect , the load receiving base is formed in an L shape by a load receiving base main body and a backrest erected on the main body of the load receiving base, and the arm is formed at an L-shaped corner portion. It is pivotally supported by the unit, and can be rotationally displaced between an upright position where the load receiving base body is leveled by the tilting drive device and a lying position where the backrest is laid down.

  ADVANTAGE OF THE INVENTION According to this invention, a load receiving stand can be raised / lowered at the stable speed, the contact pressure of a load receiving stand and the ground can be suppressed, and self-damage can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing an overall structure of a vehicle on which a load receiving platform lifting apparatus according to a first embodiment of the present invention is mounted, and is a view illustrating the load receiving platform lifting apparatus in a deployed posture, a retracted posture and an intermediate posture. . It is a perspective view of the load receiving table raising / lowering apparatus which concerns on 1st Embodiment of this invention, and is a figure showing the state which has a load receiving stand in a deployment attitude | position. It is a perspective view of the load receiving table raising / lowering device which concerns on 1st Embodiment of this invention, and is a figure showing the state which the load receiving stand grounded and fell in the guide roller. It is a perspective view of the load receiving table raising / lowering apparatus which concerns on 1st Embodiment of this invention, and is a figure showing the state in which the load receiving stand is separated from the ground and is supported by the guide roller. It is a perspective view of the load receiving table raising / lowering apparatus which concerns on 1st Embodiment of this invention, and is a figure showing the state which has a load receiving stand in a storing attitude | position. It is a perspective view of the load receiving stand with which the load receiving stand raising / lowering device which concerns on 1st Embodiment of this invention was equipped. It is a side view showing the locking device with which the load receiving table raising / lowering device which concerns on 1st Embodiment of this invention was equipped with the base unit. It is a lock | rock apparatus with which the load receiving table raising / lowering apparatus which concerns on 1st Embodiment of this invention was equipped is represented with a base unit. It is an expansion perspective view showing the structure of the vicinity of the operation lever with which the cargo receiving platform raising / lowering apparatus which concerns on 1st Embodiment of this invention was equipped. It is a circuit diagram of the hydraulic drive device of the lift drive device and tilt drive device provided in the load receiving table lifting device according to the first embodiment of the present invention. It is a circuit diagram of the relay circuit with which the control means of the load receiving table raising / lowering apparatus which concerns on 1st Embodiment of this invention was equipped. It is a schematic diagram showing the control procedure of the unfolding operation | movement of the load receiving stand by the control means with which the load receiving stand raising / lowering apparatus which concerns on 1st Embodiment of this invention was equipped. It is a timing chart of turning on and off of the command signal at the time of unfolding operation of the load receiving table by the control means provided in the load receiving table lifting device according to the first embodiment of the present invention. It is a schematic diagram showing the control procedure of the storage operation of the load receiving stand by the control means with which the load receiving stand raising / lowering apparatus which concerns on 1st Embodiment of this invention was equipped. It is a timing chart of ON / OFF of the command signal at the time of storing operation of the load receiving table by the control means provided in the load receiving table lifting device according to the first embodiment of the present invention.

  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 load receiving table lifting apparatus according to a first embodiment of the present invention, and also shows the load receiving table lifting apparatus in a deployed posture, a retracted posture and an intermediate posture. It is. The load receiving platform lifting apparatus exemplified in the present embodiment can be applied to any of so-called small vehicles, medium-sized vehicles, and large vehicles, but FIG. 1 illustrates the case where it is mounted on a small vehicle (van type vehicle). In the following description, the left and right in FIG.

  The vehicle shown in FIG. 1 includes a driver's cab 2 provided at the front of a chassis frame 1, a cargo bed 3 provided on the chassis frame 1, and a cargo bed lift provided at the rear of the cargo bed 3. A device 100 is provided. As shown in the figure, the load receiving platform lifting apparatus 100 gradually lays the L-shaped load receiving platform (platform) 30 from the posture standing up outside the rear of the load loading platform 3 (referred to as “deployment posture”), and finally the loading platform 3 By shifting the posture to the posture (referred to as “retracted posture”) lying down inside, the long load is loaded on the load receiving stand 30 in a vertically placed state and accommodated in the loading stand 3 in a laid state. When unloading the load from the loading platform 3, the loading platform 30 is displaced from the retracted position to the deployed position. Further, when in the retracted position, the load receiving platform lifting / lowering device 100 is completely accommodated in the load receiving platform 3, and if the lock device 150 described later is locked, even if the opening / closing door 4 of the load receiving platform 3 is closed, it interferes with the opening / closing door 4. Never do.

  2 to 5 are perspective views of the load receiving table elevating device 100. FIG. 2 is a state in which the load receiving stand 30 is in an unfolded position, and FIG. 3 is a state in which the load receiving stand 30 is grounded and curled by a guide roller 14 (described later). 4 shows a state in which the load receiving stage 30 is separated from the ground and is supported by the guide roller 14, and FIG. 5 shows a state in which the load receiving stage 30 is in the retracted position.

  As shown in FIGS. 2 to 5, the load receiving platform lifting device 100 includes a base unit 10 attached to the floor surface of the load carrier 3, left and right arm units 20 attached to the base unit 10, and the tip of the arm unit 20. The load receiving table 30 attached to the section, the lift driving device 40 that moves the load receiving table 30 up and down, and the tilt driving device 50 that tilts the load receiving table 30 are provided.

  The base unit 10 includes an attachment portion 11 for attaching the base unit 10 to the floor surface of the loading platform 3, a vertical joist 12 connected to the front portion of the attachment portion 11, and a stopper member 13 connected to the front portion of the vertical joist 12. I have. The attachment portion 11 is a plate-like member extending left and right, and is fixed with a bolt or the like near the rear end of the floor surface of the loading platform 3. The vertical joists 12 are a pair of left and right beams, and extend forward from the mounting portion 11. The stopper member 13 is a member that demarcates a storage space for a load with a load receiving base 31 (described later) of the load receiving base 30, and as shown in FIG. 5, the load receiving main body of the load receiving base 30 in the retracted position. The front joist 12 is joined to the front end of the vertical joist 12 by means of welding or the like so as to face the front of 31 and is erected inside the cargo bed 3. The front-rear position of the stopper member 13, that is, the length of the vertical joist 12 is set such that the rear surface of the stopper member 13 is in contact with or close to the front end portion of the load receiving table 30 in the retracted posture. In addition, a guide roller 14 for guiding a backrest 32 (described later) of the load receiving table 30 that is displaced in the retracted posture or the deployed posture is provided at the rear end portion of the base unit 10, specifically, the rear portion of the attachment portion 11. It has been done. The guide roller 14 is rotatably supported with a horizontal axis by a bracket 15 projecting from the rear portion of the attachment portion 11. In this embodiment, the guide roller 14 is installed at two left and right sides, and the opening / closing door 4 of the loading platform 3 is attached to the guide roller 14. Even when closed, the door 4 is arranged so as not to contact the door 4.

  Although not shown in FIGS. 2 to 5 for the purpose of preventing the figure from being complicated, the base unit 10 is provided with a lock device 150 that restrains the load receiving platform 32 in the retracted position. The locking device 150 will be described later with reference to FIGS.

  The arm unit 20 includes a parallel link arm 21 attached to the base unit 10 and a support arm 22 connected to the distal end portion of the parallel link arm 21. The parallel link arm 21 has a first link arm 28 and a second link arm 29. The base ends of the link arms 28 and 29 are connected to base brackets 23 arranged on the left and right sides on the mounting portion 11 of the base unit 10 via pins 24 and 25, respectively, and the tip ends are supported by the above-described support. The arm 22 is connected to the upper part (base end part) via pins 26 and 27, respectively. The support arm 22 extends downward from the connecting portion with the parallel link arm 21. The shape drawn by connecting the pins 24-27 of the parallel link arm 21 is a parallelogram shape, and the parallel link arm 21 literally constitutes a parallel link and protrudes backward from the inside of the cargo bed 3 (hereinafter referred to as “lowering position”). And a position that stands up from the floor of the loading platform 3 (hereinafter referred to as an “upward position”) inside the loading platform 3.

  A pin 41 is provided between the pins 25 and 27 of the second link arm 29, and both ends of the lift driving device 40 are connected to the pin 41 and the pin 26 at the tip of the first link arm 28. Each is connected. An electric or hydraulic cylinder (a double-acting hydraulic cylinder in the present embodiment) is used for the lift drive device 40 provided on the parallel link arm 21, but an electric or hydraulic motor can also be applied. The parallel link arm 21 is rotationally displaced between the lowered position and the raised position in accordance with the expansion / contraction operation of the lift driving device 40, and specifically, the direction in which the lift driving device 40 extends (the raised position direction). Further, the parallel link arm 21 is rotationally displaced rearward (downward position direction) by contracting. At this time, since the parallel link arm 21 is a parallel link as described above, when the parallel link arm 21 rotates, the support arm 22 moves up and down while drawing an arcuate locus while maintaining a vertically extended posture. (See also FIG. 1).

  The load receiving stand 30 is formed in an L shape by a load receiving stand main body 31 and a backrest 32 erected on the front part of the load receiving stand main body 31. Both the load receiving table body 31 and the backrest 32 are plate-like members having substantially the same width, and the strength is enhanced by the brace 35. A rotation shaft 33 protrudes left and right at an L-shaped corner portion of the load receiving base 30 (near the boundary between the load receiving body 31 and the backrest 32), and the rotation shaft 33 is a lower end (front end) of the left and right support arms 22. Part). Accordingly, the load receiving platform 30 is pivotally supported by the support arm 22 at the L-shaped corner portion, and the load receiving platform main body 31 is horizontally positioned as shown in FIG. 2 (hereinafter referred to as “standing position”) and as shown in FIG. It can be rotated and displaced between positions where the backrest 32 is laid down (hereinafter referred to as “falling position”). Here, the “position where the backrest 32 defining the lying position is laid” means the position where the backrest 32 is laid down to the storage position of the luggage in the cargo bed 3 when the vehicle travels. Although the position where the droop 32 is horizontal is defined as the lying position, the posture in which the back 32 is inclined, for example, when loading a baggage that has a situation where liquid is stored inside and cannot be laid down completely horizontally May also be included.

  Also, brackets 34 are provided on the left and right sides of the back surface of the backrest 32 in the vertical direction, and both ends of the tilt drive device 50 are connected to the brackets 51 and the support arm 22 on the left and right sides, respectively. They are connected via 52. The pin 52 passes through a position near the front of the rotating shaft 33 in the lower part of the support arm 22. An electric or hydraulic cylinder (in this embodiment, a double-acting hydraulic cylinder) is used for the tilting drive device 50, but an electric or hydraulic motor can also be applied. As the tilting drive device 50 expands and contracts, the load receiving platform 30 tilts about the rotation shaft 33. Specifically, the load receiving platform 30 extends in the direction of standing when the tilting driving device 50 extends, and in the direction of lying down when contracting. 30 is rotationally displaced.

  Here, although not illustrated in FIGS. 2 to 5, the load fixing fixing devices 36 and 37 (FIG. 6) that can be attached to and detached from the load receiving table 30 and the load receiving table 30 in the retracted position are mechanically restrained. A locking device 150 (FIGS. 7 to 9) is provided.

  FIG. 6 is a perspective view illustrating fixing devices 36 and 37 together with the load receiving platform 30. In this figure, the bracing 35, the rotary shaft 33, and the bracket 34 are not shown.

  As shown in FIG. 6, the load receiving platform 30 is provided with a large number of mounting holes 38 for fixing the fixing devices 36 and 37. In the present embodiment, the case where the mounting holes 38 are regularly arranged in the backrest 32 is illustrated, but the drilling position and arrangement of the mounting holes 38 are not particularly limited. A mounting hole 38 can be provided. The fixing devices 36 and 37 are optional, and are fixed to the mounting holes 38 with bolts and nuts. The configuration of the fixing devices 36 and 37 is not particularly limited, but is determined in consideration of the fixing posture of the load mounted on the load receiving platform 30 and the like. For example, since the load is tilted during the storage operation of the load receiving platform 30, for example, the baggage is filled by filling a gap between the backrest 32 and the load so that the load does not rattle during the tilting operation and the posture after lying down. The fixing devices 36 and 37 are appropriately formed so as to be restrained. Therefore, when the fixing devices 36 and 37 are used, the load is supported on the backrest 32 via the fixing devices 36 and 37 when the cargo receiving platform 30 shifts to the retracted position. Although not particularly illustrated, the attachment holes 38 other than those used for fixing the fixing devices 36 and 37 can be used for fixing a securing means such as a rope or a band, and are set in the fixing devices 36 and 37. The state luggage can be secured by lashing means. In the present embodiment, two sets of fixing devices 36 and 37 are illustrated, but the number of fixing devices may vary depending on the shape of the luggage.

  Although not shown in FIGS. 2 to 5, in the present embodiment, the receiving platform 30 is provided with a locking portion 39 on the backrest 32. The configuration of the locking portion 39 is not particularly limited as long as the hook 152 (see FIG. 7 and the like) of the locking device 150 to be described later is applied, but in the present embodiment, the corner portions on both the left and right sides of the upper end portion of the backrest 32. Are provided as a locking portion 39 by providing a pin extending in the left-right direction.

  FIG. 7 is a side view showing the configuration of the locking device 150 together with the base unit 10, and FIG. 8 is a plan view thereof. 7 and 8, the right and left in the figure are front and rear.

  As shown in FIGS. 7 and 8, the lock device 150 converts the operation lever 151, the hook 152 to be engaged with the engagement portion 39 of the cargo receiving table 30, and the operation of the operation lever 151 into the operation of the hook 152. And a link mechanism 153.

  The operation lever 151 is provided so as to rotate back and forth via a shaft 155 extending in the left-right direction with respect to a box 154 provided on the left and right end portions (right side in the present embodiment) of the mounting portion 11 of the base unit 10. It has been. Since this operation lever 151 is located at the rear part of the load receiving platform lifting / lowering device 100, if the opening / closing door 4 of the loading platform 3 of the vehicle is opened, the operator can easily reach it, and the standing position (hereinafter referred to as “lock position”). Is not interfered with the movable region of the open / close door 4, but when it is at the rearward position (hereinafter referred to as “unlock position”), only the length L (see FIG. 7) behind the guide roller 14. It interferes with the movable region of the protruding door 4. Thus, the locking device 150 is not locked (not in the locking position) when the opening / closing door 4 cannot be closed by interfering with the operation lever 151 in the unlocking position to prevent the opening / closing door 4 from being closed. The worker can understand this.

  In the present embodiment, the operation lever 151 of the locking device 150 interferes with the opening / closing door 4 when in the locked position, but the portion that interferes with the opening / closing door 4 is not limited to the operation lever 151, The part may interfere with the opening / closing door 4, or a dedicated member may be separately provided only to cause interference with the opening / closing door 4 when in the locked position. For example, a contact member that is rod-shaped and longer than the operation lever 151 is separately attached to the shaft 155 in parallel with the operation lever 151 so that the contact member protrudes rearward from the operation lever 151 when the operation lever 151 is operated to the lock position. Thus, it can be considered that the contact member, not the operation lever 151, interferes with the open / close door 4 when in the locked position. In this case, since the operation lever 151 does not interfere with the door 4, it is possible to prevent the operation lever 151 that is an indispensable member for causing the locking device 150 to function from being damaged by the interference with the door 4. .

  The link mechanism 153 includes a plurality of link arms 156-162. The link arm 156 extends from the shaft 155 to the opposite side of the operation lever 151 and is connected to one end of the link arm 157. The other end of the link arm 157 is connected to a link arm 158 fixed to the shaft 163. The shaft 163 is rotatably supported in a posture extending left and right by a support member 164 provided at the front portion of the box 154 and a support member 165 provided at the attachment portion 11. A link arm 160 is connected to the shaft 163 via a link arm 159, and one end of a link arm 161 extending in the front-rear direction is connected to the link arm 160. The other end of the link arm 161 is connected to a link arm 162 fixed to the shaft 166. The shaft 166 passes through the vicinity of the front end portion of the left and right vertical joists 12 and extends in the left-right direction, and is supported rotatably with respect to the vertical joists 12.

  The hook 152 is fixed to the shaft 166. The hooks 152 are provided on the left and right, the left hook 152 is positioned on the left side of the left vertical joist 12, and the right hook 152 is positioned on the right side of the right vertical joist 12. When the operation lever 151 falls from the locked position (see the solid line in FIG. 7) to the unlocked position (see the one-dot chain line in FIG. 7), the shaft 155, the link arm 156-158, the shaft 163, and the link arm 159-162. And the movement of the operating lever 151 is transmitted to the hook 162 via the shaft 166, and the hook 152 can be engaged with the locking portion 39 (only the locking portion 39 is shown in FIG. 7) of the load receiving base 30 in the retracted position (see FIG. 7). 7) (see a solid line in FIG. 7). On the other hand, when the operation lever 151 is raised from the unlocked position to the locked position, the hook 152 falls from the unlocked position to the locked position.

  FIG. 9 is an enlarged perspective view showing a configuration in the vicinity of the operation lever 151.

  As shown in FIG. 9, a lock sensor 167 that detects that the lock device 150 is in the locked position or the unlocked position is attached to the inner wall of the box 154. Various sensors can be applied to the lock sensor 167, but in this embodiment, a limit switch is used, and when the operation lever 151 moves to the unlocking position, it contacts the link arm 156 extending in the same direction as the operation lever 151. Accordingly, the limit switch is turned on, and it is detected that the lock device 150 is in the unlocked position. The detection signal of the lock sensor 167 is output to the controller 90 described later. Although details will be described later, when it is determined that the lock device 150 is in the lock position based on the signal from the lock sensor 167, the controller 90 disables the operations of the lift drive device 40 and the tilt drive device 50. The

  In the present embodiment, the posture displacement of the link arm 156 is detected by the lock sensor 167. However, the displacement of the operation lever 151 may be directly detected, and the postures of the other link arms 157-162 and the hook 152 may be detected. By detecting the displacement or the rotation angle of the shafts 155, 163 and 166, it can be detected that the lock device 150 is in the lock position or the unlock position.

  FIG. 10 is a circuit diagram of the hydraulic drive device of the lift drive device 40 and the tilt drive device 50 provided in the load receiving table lifting device 100.

  10 includes a tank 61 that stores hydraulic oil, a hydraulic pump 62 that sucks up and discharges the hydraulic oil in the tank 61 via a filter, and a drive device (for example, an electric motor) that drives the hydraulic pump 62. 60, the lift driving device 40 and the tilt driving device 50 connected in parallel to the discharge pipe 63 of the hydraulic pump 62, and a three-position switching for controlling the flow of hydraulic oil to the lift driving device 40 and the tilt driving device 50 Control valves 64 and 65 of the type.

  A variable throttle type throttle valve unit 67 is provided in the hydraulic oil line 66 that connects the control valve 64 and the bottom side oil chambers of the left and right lift driving devices 40, and is supplied to the bottom side oil chambers of the lift driving device 40. The flow rate of the working oil to be discharged and the working oil discharged from the oil chamber is throttled by the throttle valve unit 67. In addition, variable throttle type throttle valve units 70 and 71 are also provided in hydraulic oil pipes 68 and 69 that connect the control valve 65 and the bottom and rod side oil chambers of the left and right tilt drive devices 50, respectively. The flow rates of the hydraulic oil discharged from the bottom side oil chamber of the tilt drive device 50 and the hydraulic oil discharged from the rod side oil chamber are throttled by the throttle valve units 70 and 71, respectively. The hydraulic oil pipes 68 and 69 of the tilt driving device 50 are connected by a bypass pipe 72. By opening the switching valve 73 provided in the bypass pipe 72, the tilt driving device 50 becomes free.

  The discharge pipe 63 is connected to a return pipe 74 connecting the control valves 64 and 65 and the tank 61 via relief pipes 75 and 76. One relief pipe 75 is provided with a relief valve 77 for circuit protection, and the other low-pressure relief pipe 76 is provided with a low-pressure relief valve 78 and a switching valve 79. The relief pressure of the low pressure relief valve 78 is set lower than that of the relief valve 77, and the relief pressure of the discharge pipe 63 is reduced to the relief pressure of the low pressure relief valve 78 by opening the switching valve 79.

  Further, the discharge pipe 63 is connected to the tank 61 via an auxiliary pipe 80, and a hand pump 81 is provided in the auxiliary pipe 80. By driving the hand pump 81 manually, the hydraulic drive device can be driven even when the hydraulic pump 62 cannot be used.

  The control valves 64 and 65 and the switching valves 73 and 79 are controlled to be switched by a command signal from a controller (control means) 90 provided in the cargo receiving table lifting device 100. At this time, although not particularly illustrated, the load receiving platform lifting / lowering device 100 has an arm sensor for detecting that the parallel link arm 21 is not in the raised position, and the backrest 32 of the load receiving platform 30 is in contact with the guide roller 14. And a ground sensor for detecting that the load receiving stand 30 is in contact with the ground, a detection signal Sarm from the arm sensor, a detection signal Sgrd from the ground sensor, and a detection from the roller sensor. Each signal Srol is input to the controller 90. When the controller 90 inputs an operation signal from a storage switch 97 or a deployment switch 98, which will be described later, and starts a storage operation or a deployment operation of the receiving platform 30, the detection signal Sarm, Sgrd, Srol input during the operation is used as a trigger. Then, command signals Ssol1-Ssol6 to the control valves 64, 65 and the switching valves 73, 79 are appropriately output. As a result, the controller 90 controls the lift drive device 40 and the tilt drive device 50 in conjunction with each other to displace the load receiving platform 30 between the deployed posture and the retracted posture.

  The correspondence relationship between the command signals Ssol1 to Ssol6 and the output destination / resulting operation is as follows.

Ssol1: Control valve 64 / lift drive device 40 expands Ssol2: Control valve 64 / lift drive device 40 retracts Ssol3: Control valve 65 / tilt drive device 50 expands Ssol4: Control valve 65 / tilt drive device 50 retracts Ssol5: The switching valve 79 / relief pressure decreases Ssol6: the switching valve 73 / tilting drive device 50 becomes free. As an arm sensor, for example, an angle sensor or a parallel link provided on one of the pins 24-27 of the parallel link arm 21 A proximity sensor (distance sensor) that detects the distance between the arm 21 and the support arm 22 can be used. As a grounding sensor, a proximity sensor (distance sensor) that detects the distance to the ground at the corner of the load receiving table 30, a limit switch that enters when the corner of the load receiving table 30 contacts the ground, and pins 24-27 of the parallel link arm 21 An angle sensor provided in any of them (calculating the height of the load receiving platform 30 with the arm angle) or the like can be used. As a roller sensor, a proximity sensor (distance sensor) for detecting the distance between the guide roller and the backrest 32 of the load receiving table 30 is provided at a support portion of the guide roller 14 (when the load is applied to the guide roller 14, the roller sensor is turned on). ) A limit switch or the like can be used.

  FIG. 11 is a circuit diagram of a relay circuit provided in the controller 90.

  The relay circuit shown in FIG. 11 includes contacts 91-93 that close the contacts when the detection signals of the arm sensor, the ground sensor, and the roller sensor are received in addition to the driving device 60 and the lock sensor 167 described above, and the load receiving platform lifting device 100. A main power switch 94, a buzzer (leaving device) 95 for notifying that the main power is turned on with a notification sound, and a notification sound for notifying that the lock sensor 167 is off (the lock device 150 is in the unlocked position). Buzzer (notification device) 96, storage switch 97 for instructing the storage operation, expansion switch 98 for instructing the expansion operation, relay coils R1 to R4, T1, T2, CT, and these relay coils R1 to R4, T1, T2, CT Are provided with relay contacts R1 ′ to R4 ′, T1 ′, T2 ′, and CT ′, which are activated when excited.

  Although there are three relay contacts R2 ', two of them are overlapping contacts having two contacts, and when the relay coil R2 is excited, either of the two contacts is selectively turned on. The relay coils T1 and T2 are on-delay timer coils. When the excitation state continues for a set time, the corresponding on-delay timer contacts T1 'and T2' are activated after the set time has elapsed since the start of excitation. The main power switch 94 and the buzzer 95 are disposed in the cab 2, and the storage switch 97 and the unfolding switch 98 are disposed, for example, on a remote controller in the loading platform 3.

  Next, operations and effects of the load receiving table lifting apparatus 100 having the above-described configuration will be described in order.

1. Deployment Operation FIG. 12 is a schematic diagram showing a control procedure of the deployment operation of the load receiving table 30 by the controller 90, and FIG. 13 is a timing chart of turning on / off command signals to the control valves 64, 65, 73, 79. The unfolding operation will be described below using FIGS. 12 and 13 with reference to FIGS.

(Step A)
In order to operate the load receiving platform lifting apparatus 100, first, the main power switch 94 of the load receiving platform lifting apparatus 100 is turned on in the cab 2. When the main power is turned on, as shown in the relay circuit of FIG. 11, the buzzer 95 is energized to output a notification sound in the cab 2 and to notify the cab 1 that the main power is turned on. The This notification sound sounds continuously while the main power switch 94 is on. Next, it turns to the rear part of the vehicle, opens the opening / closing door 4 of the loading platform 3, and causes the operation lever 151 of the locking device 150 to fall to the unlocking position. As a result, the lock sensor 167 is turned on, and when the buzzer 96 is energized, a notification sound is output to the rear of the vehicle, and it is notified to the surroundings of the vehicle that the lock device 150 is in the unlocked position. This notification sound sounds continuously while the lock device 150 is in the unlocked position. At this time, the receiving platform 30 is in the retracted position, and the detection signals Sarm, Sgrd, and Srol are all in an OFF (off) state.

  Next, when the expansion switch 98 is operated, the controller 90 outputs the command signals Ssol2 and Ssol6 to the control valve 64 and the switching valve 73. The control valve 64 is set to the left position in FIG. 10, and the switching valve 73 is set to the upper position. Switch. As a result, the rod side oil chamber of the lift drive unit 40 is connected to the discharge line 63 of the hydraulic pump 62, and the bottom side and rod side hydraulic oil lines 68 and 69 of the tilt drive unit 50 are connected. At the same time, the contactor relay coil CT is excited to close the contactor relay contact CT ', the drive device 60 is driven, and the hydraulic pump 62 is driven. As a result, the lift drive device 40 is retracted and the tilt drive device 50 is free (expandable state). As a result, after the load receiving platform 30 is lifted by the parallel link arm 21 and the backrest 32 is slightly lifted from the vertical joist 12, it starts to descend rearward. When step A is executed, the parallel link arm 21 starts to move from the raised position, and the parallel link arm 21 leaves the raised position, so that the detection signal Sarm from the arm sensor is immediately turned ON (on), and the procedure goes to step B. Will migrate. In FIG. 12, ON / OFF of the detection signals Sarm, Srol, and Sgrd is indicated by the presence or absence of “◯”. The same applies to FIG. 14 described later.

(Step B)
In Step B, when the detection signal Sarm from the arm sensor is entered and the contact 91 is closed, the relay coil R1 is excited and the corresponding relay contact R1 ′ is activated. As a result, the command signal Ssol3 is output from the controller 90 to the switching valve 73, and the control valve 65 is switched to the right position in FIG. As a result, the bottom side and rod side hydraulic oil pipes 68 and 69 of the tilt drive device 50 are connected to the tank 61, and the followability of the tilt drive device 50 is increased. The command signals Ssol2 and Ssol6 are continuously output. As a result, the load receiving platform 30 descends from the loading platform 3 together with the support arm 22 in accordance with the operation of the parallel link arm 21 and moves backward while drawing an arcuate locus. This descending speed is moderately suppressed by the action of the throttle valve unit 67.

  For example, in this step B and the next step C, the lift driving device 40 is subjected to an urging force in a direction in which the lift driving device 40 contracts due to the action of its own weight such as the load receiving platform 30. Therefore, even if hydraulic oil is not positively supplied to the rod side oil chamber, the bottom side oil chamber is connected to the tank 61, so that it operates in the unfolding direction with its own weight such as the load receiving platform 30. Therefore, in order to suppress minute vibrations that may occur in the load receiving platform 30 during the lowering operation due to the pulsation of the hydraulic oil caused by the piston operation of the hydraulic pump 62, the rotational speed of the hydraulic pump 62 is reduced when the load receiving platform 30 is lowered. It is also conceivable to reduce the discharge flow rate by dropping it so that the weight of the load receiving platform 30 or the like becomes dominant as a driving source for the lowering operation.

(Step C)
Immediately after the execution of Step B, the backrest 32 of the load receiving table 30 comes into contact with the guide roller 14. As a result, the detection signal Srol from the roller sensor is entered, the contact 93 is closed, the relay coils R3 and T2 are excited and the relay contacts R3 ′ and T2 ′ are activated, but the output state of the command signal does not change during the unfolding operation. While the output states of the command signals Ssol2, Ssol3, and Ssol6 are maintained, the backrest 32 rises following the guide roller 14 as the support arm 22 is further lowered. When the support arm 22 further descends and the corner portion of the load receiving platform 30 contacts the ground, the detection signal Sgrd from the ground sensor is turned on (ON), and the procedure proceeds to the subsequent step D.

(Steps D and E)
In Step D, the detection signal Sgrd from the ground sensor is entered, the contact 92 is closed, and the relay coils R2 and T1 are excited. As a result, the relay contact R2 ′ is first activated, the command signal Ssol5 is output to the switching valve 79, and the switching valve 79 is switched to the upper position in FIG. As a result, the relief pressure of the hydraulic circuit of the hydraulic drive device is switched to a low-pressure relief pressure by the low-pressure relief valve 78, and an excessive pressing force does not act between the load receiving platform 30 and the ground. When the relay coil T1 is excited and the set time t1 elapses, the on-delay timer contact T1 ′ is opened, and the output of the command signal Ssol6 is stopped, so that the switching valve 73 returns to the lower position in FIG. As a result, the tilting drive device 50 is released from the free state and starts to extend, and the load receiving platform 30 shifts from the posture of the guide roller 14 to the deployed posture (step E) starting from the corner portion. During this time, that is, while the detection signal Sgrd is input from the ground sensor, the controller 90 opens the switching valve 79 and maintains the state where the relief pressure is lowered.

  When the operation of the deployment switch 98 is stopped after the load receiving table 30 reaches the standing position and the load receiving table 30 shifts to the deployed position, the controller 90 stops the command signals Ssol2, Ssol3, Ssol5 being output and receives the load. The unfolding operation of the table 30 is finished.

  Note that when the detection signal Srol from the roller sensor is cut off, the relay coil R3 is not excited and the relay contact R3 'operates, but at the time of step D, the output state of the command signal is not affected. Further, the execution of step D is limited to, for example, a preset time T0. When the set time T0 has elapsed after the start of execution of step D, the controller 90 stops the command signals Ssol2, Ssol3, Ssol5 being output. The unfolding operation of the receiving platform 30 is finished. The time T0 is, for example, the time required to shift from a state where the load receiving table 30 is in contact with the ground and the guide roller 14 to a state where the load receiving table 30 is in contact with the bottom surface of the load receiving table main body 31 and stands up (deployed posture).

2. Storage Operation FIG. 14 is a schematic diagram showing a control procedure of the storage operation of the cargo receiving platform 30 by the controller 90, and FIG. 15 is a timing chart of turning on and off command signals to the control valves 64, 65, 73, and 79. The storing operation will be described below with reference to FIGS. 14 and 15 with reference to FIGS.

(Step F)
At this time, the load receiving stand 30 is in the unfolded posture, and the detection signals Sarm and Sgrd are ON and the detection signal Srol is OFF. When the retract switch 97 is operated, the controller 90 outputs the command signal Ssol4 to the control valve 65, and switches the control valve 65 to the left position in FIG. As a result, the rod side oil chamber of the tilt drive device 50 is connected to the discharge pipe 63 of the hydraulic pump 62. At the same time, the contactor relay coil CT is excited to close the contactor relay contact CT ′, the drive device 60 is driven, and the hydraulic pump 62 is driven. As a result, the tilting drive device 50 is retracted, and in the state where the load receiving platform 30 is grounded at the corner portion, the tilting drive device 50 rotates in the retracted direction and hangs on the guide roller 14. When the backrest 32 of the load receiving platform 30 leans on the guide roller 14 and the detection signal Srol of the roller sensor is turned on, the controller 90 moves the procedure to Step G.

(Step GJ)
In Step G, the detection signal Srol from the roller sensor is entered, the contact 93 is closed, and the relay coils R3 and T2 are excited. As a result, the relay contact R3 ′ is first activated, the command signal Ssol6 is output to the switching valve 73, and the switching valve 73 is switched to the upper position in FIG. As a result, the tilting drive device 50 becomes free once, and the load receiving platform 30 stands against the guide roller 14 by its own weight. When the relay coil T2 is excited and the set time t2 elapses, the on-delay timer contact T2 ′ is closed, the command signal Ssol1 is output to the control valve 64, and the control valve 64 is switched to the right position in FIG. The lift driving device 40 starts the extending operation. At the same time, the output of the command signal Ssol6 is stopped, and the switching valve 73 returns to the lower shut-off position, whereby the tilting drive device 50 operates on the sloping side, and the backrest 32 of the load receiving table 30 is pressed against the guide roller 14. It is done. In this way, the load receiving platform 30 moves upward while being pressed against the guide roller 14.

  As the storage operation progresses, the detection signals Sgrd and Srol from the ground sensor and roller sensor are sequentially turned off (steps H and I), and the detection signal Sarm from the arm sensor is turned on (step J). As in 11 relay circuit, the output state of the command signal is not switched during this time, and the output of the command signals Ssol1 and Ssol4 is maintained. In a state in which the backrest 32 having a length longer than that of the load receiving body 31 is in contact with the guide roller 14, the center of gravity of the load receiving stand 30 is in front of the rotation shaft 33, and thus the process of rising in an arc with the support arm 22. Thus, the load receiving platform 30 also tilts in the retracted direction while following the guide roller 14 due to its own weight.

  When the operation of the storage switch 97 is stopped after the parallel link arm 21 reaches the ascending posture and the load receiving table 30 shifts to the retracted posture, the controller 90 stops the output command signals Ssol1 and Ssol4 and stops the load receiving table. 30 storing operation is completed. Even during the storage operation, the ascending speed and the tilting speed of the load receiving platform 30 are moderately suppressed by the action of the throttle valve units 67, 70, 71.

  When the storage operation is completed, the lock device 150 and the operation lever 151 of the lock device 150 are raised at the lock position, and the backrest 32 of the load receiving platform 30 is restrained by the hook 152. As a result, the lock sensor 167 is turned off, the electric path to the buzzer 96 is interrupted, and the buzzer 96 stops ringing. Thereafter, the opening / closing door 4 of the cargo bed 3 is closed and the operation room 2 is returned to, and the main power switch 94 is turned off. When the main power is turned off, the electric circuit to the buzzer 95 is interrupted and the buzzer 95 stops ringing.

  Next, operational effects obtained by this embodiment will be described.

  (1) As described above, in this embodiment, a double-acting hydraulic cylinder is used for the lift driving device 40, and the force of the hydraulic oil is also used for the lowering operation of the load receiving table 30. Not only the ascending speed but also the descending speed can be controlled by the hydraulic oil supply flow rate. Therefore, compared with the case where the weight of the load receiving platform or the like is used for the lowering operation of the load receiving platform using the single-acting hydraulic cylinder, the influence of the viscosity of the hydraulic oil on the lowering speed of the load receiving platform 30 can be suppressed. Can be stabilized.

  In addition, in this embodiment, while the load receiving platform 30 is installed during the unfolding operation, that is, while the detection signal Sgrd is input from the ground sensor during the lowering operation of the arm unit 20, The switching valve 79 is opened, and the relief pressure of the circuit is lowered from a normal relief pressure for circuit protection by the relief valve 77 to a lower relief pressure by the low pressure relief valve 78. For this reason, the load receiving platform 30 comes into contact with the ground or the like until the lift driving device 40 reaches the specified amount of contraction, and the load receiving table 30 is brought to the ground or the like by the lift driving device 40 trying to continue the contraction to the specified amount of contraction. Even in a situation where the load receiving table 30 is pressed, the contact pressure acting between the load receiving platform 30 and the ground or the like is limited by the relief pressure of the low pressure relief valve 78, so that the force that the load receiving platform 30 is pressed against the ground or the like can be suppressed. . Thereby, the load receiving platform lifting device 100 does not push the ground with the load receiving platform 30 to lift the rear part of the vehicle, and the damage of the load receiving platform lifting device 200 due to the load of the vehicle applied to the arm unit or the like can be suppressed. it can.

  Therefore, according to the present embodiment, the load receiving platform 30 can be moved up and down at a stable speed by using the double-acting lift driving device 40, and the load receiving platform 30 can be used even when the double-acting lift driving device 40 is used. Since the contact pressure with the ground and the like can be suppressed, damage to the load receiving table lifting device 100 can be suppressed.

  (2) Further, in this embodiment, the tilt drive device 50 is provided in addition to the lift drive device 40, and the extending operation (operation toward the standing position) of the tilt drive device 50 supplies hydraulic oil to the tilt drive device 50. By running. Therefore, for example, the load receiving base main body 31 may be strongly pressed against the ground or the like before the tilt drive device 50 is extended by a predetermined amount due to, for example, an inclination or unevenness on the ground or a foreign object falling. In this case as well, an excessive load can be applied to the load receiving table lifting device 100.

  On the other hand, in the present embodiment, the tilt drive device 50 is connected in parallel with the lift drive device 40, and both the drive devices 40, 50 are driven by a common hydraulic pump 62. Since the low-pressure relief pipe 76 is provided in the discharge pipe 63 of the hydraulic pump 62 before the hydraulic oil supply pipe branches in the device 50, the lift pressure is increased when the relief pressure is switched to that of the low-pressure relief valve 78. Not only the operating load of the driving device 40 but also the operating load of the tilting driving device 50 can be limited by the relief pressure of the low pressure relief valve 78. Therefore, an excessive load that can be applied to the components of the load receiving platform lifting apparatus 100 by the tilting drive apparatus 50 can also be suppressed.

  Further, when the tip of the load receiving table 30 is floating from the ground, it is not possible to smoothly load and unload the load, and when the tip of the load receiving table 30 is lifted from the ground, there is a problem in terms of product quality. Is required to be fully grounded. Therefore, in the present embodiment, by operating the lift driving device 40 and the tilting driving device 50 while regulating the contact pressure with the low pressure relief valve 78, the entire surface of the load receiving platform 30 can be applied within a range in which no excessive load is applied to the load receiving device lifting / lowering device 100. Therefore, the load receiving platform can be securely grounded with peace of mind, and the lifting of the load receiving platform 30 from the ground can be prevented.

  (3) Also, when the load receiving platform 30 is lowered as in the present embodiment, when the load receiving platform 30 is pressed against the ground even when touching the ground, the operating pressure of the lift drive device 40 is set to be equivalent to that during the lifting drive. As described above, since a strong force is applied to the constituent members of the load receiving base lifting device 100 such as the load receiving base 30 and the arm unit 20, these constituent members are required to have high durability with little secular change. However, for example, when the load receiving platform 30 is increased in thickness in order to improve the durability of the constituent members, the weight of the load receiving platform lifting / lowering device 100 increases and the fuel efficiency of the vehicle decreases. In recent years when environmental issues are regarded as important, a design that leads to a reduction in fuel efficiency is not preferable. In addition, various loading platform lifting devices for standing and storing the loading platform at the rear part of the loading platform (for example, disclosed in JP 2008-189189 A, JP 2007-331631 A, JP 2004-224082 A, etc.) )), The total length of the vehicle including the cradle standing up at the rear of the cradle must be within the limit value of the vehicle length of the general road. The front and rear length of the loading platform must be shortened, and the load capacity can be reduced.

  On the other hand, in the present embodiment, as described above, the contact pressure between the ground and the load receiving table can be suppressed, so that the thickness of the load receiving table 30 or the like can be avoided. Accordingly, it is possible to avoid the weight increase of the load receiving platform lifting apparatus 100 and to suppress a decrease in the fuel efficiency of the vehicle. In addition, since it is possible to avoid increasing the thickness of the load receiving platform 30 and the like, even when the present invention is applied to a type of load receiving platform lifting device that raises the load receiving platform at the rear of the loading platform, it is possible to suppress a decrease in load capacity. it can.

  (4) Also, for example, when a load is unloaded from a vehicle or an operator gets off the vehicle, the load weight of the vehicle is reduced accordingly, so that the suspension of the vehicle is slightly extended and the height of the vehicle (chassis frame 1) is increased. Rises. For this reason, even when the cargo cradle 30 is unfolded and initially in a grounded state, if the vehicle is lifted by unloading a load or an operator getting off, the cradle 30 may also follow the vehicle and lift away from the ground. . This is a great demerit as a cargo receiving elevating device.

  On the other hand, in the present embodiment, since the load receiving platform 30 is pressed against the ground for the set time t1 before the post-contacting load receiving platform 30 is tilted during the unfolding operation, the vehicle may be slightly floated during the set time t1. it can. Thereby, when a luggage | load etc. are dropped from a vehicle after that, it can suppress that the load receiving stand 30 floats from the ground with a vehicle.

  (5) Further, according to the present embodiment, since the load receiving platform 30 rises from the deployed posture standing on the ground and falls to the retracted posture in the load loading platform 3, the long load is loaded on the load receiving platform 30. It can be loaded in a standing state and can be accommodated in a state in which it is laid down on the cargo receiver 3. In particular, when the loading platform 3 of the vehicle is a cargo box as in this embodiment, that is, when the loading platform 3 has a ceiling, it is possible to incline while raising and lowering the loading as in this embodiment, A load can be loaded on the loading platform 3 while avoiding interference.

  (6) At the start of the unfolding operation (step A in FIG. 12), the lift driving device 40 is contracted and the load receiving platform 30 is pulled out horizontally behind the loading platform 3, but during this time, the tilt driving device 50 is temporarily extended. When the posture of the load receiving platform 30 changes from step A to step B when operating in the direction, the load receiving stand 30 is in the posture where the load receiving stand 30 starts to stand up slightly from the lying down posture or the lying down posture. A force that positively presses 30 downward is generated. As a result, the load receiving table 30 is pressed against the guide roller 14 more than necessary, and the horizontal pulling operation may not be performed smoothly. There is a particular concern when a heavy object is placed on the load receiving platform 30.

  On the other hand, as shown in FIG. 12, the controller 90 of the present embodiment makes the tilting drive device 50 free when moving the load receiving platform 30 from the lying position during the unfolding operation. As a result, the load receiving table 30 is not pressed against the guide roller 14 by the tilting driving device 50 when the state transitions from the step A to the step B, and the backrest 32 of the load receiving table 30 is made to follow the guide roller 14 smoothly. Can be pulled out backwards.

  (7) Moreover, in the case of this embodiment, the case where the loading platform raising / lowering apparatus 100 is mounted in the loading platform 3 of a van type vehicle, in other words, the loading box of a vehicle, is illustrated. In this case, if the opening / closing door 4 of the loading platform 3 is closed in the retracted position, the surroundings of the loading platform lifting / lowering device 100 are covered with the wall surface of the loading platform 3 and the opening / closing door 4. Can protect precision equipment from the surrounding environment, and can also protect the load receiving table lifting apparatus 100 itself, thereby reducing the labor required for maintenance.

  In the above embodiment, the case where the tilt driving device 50 that actively tilts the load receiving table 30 is described as an example. However, when the tilting operation of the load receiving table 30 is guided by the guide roller 14, The tilt drive device 50 is not always necessary. The operation of leaning the load receiving table 30 on the guide roller 14 from the deployed posture and the operation that is caused to move from the posture leaning on the guide roller 14 to the deployed posture can be performed manually without using an actuator. When these operations are performed by human power, for example, the load receiving table 30 and the support arm 22 are connected by a biasing means such as a gas spring, and the load receiving table 30 is weaker than the force by which the load receiving table 30 is inclined by its own weight in the storing direction. By urging the load receiving table 30 in the unfolding direction with force, the operation of shifting the load receiving table 30 to the unfolding position is assisted, and the cushion is also supported when the load receiving table 30 is leaned against the guide roller 14 from the unfolding position. Play a role. A cylindrical biasing means such as a gas spring can be substituted for the tilting drive device 50, and a device utilizing a torsion return force such as a torsion bar is also applicable.

  Further, in the above embodiment, the case where the load receiving table 30 integrally formed in an L shape is used has been described as an example. However, the backrest 32 is rotatably connected to the load receiving body 31. It is good also as a structure which can be folded on the load receiving body 31 or the backrest 32 can be removed from the load receiving body 31. In such a configuration, the backrest 32 is removed or folded to change the shape of the load receiving platform 30 into a horizontal plate shape, so that the load receiving platform main body 31 is lifted and lowered with the support arm 22 in a horizontal posture without being tilted. Specifically, by operating the parallel link arm 21 while the tilting drive device 50 is maintained in the extended state, the load receiving platform 30 can be lifted and lowered in the horizontal posture. That is, it can also be used as a normal load receiving table lifting / lowering device on which a load or an operator is placed. Further, when the lift driving device 40 is operated, the control for keeping the tilt driving device 50 in the extended state and the control for extending and retracting the tilt driving device 50 as in the above-described embodiment can be performed by switching. Therefore, it can also be used as a general load receiving device lifting device that lifts and lowers the load receiving body 31 in a horizontal state, and for the purpose of laying and loading a load by changing the posture of the load receiving table 30 as in the above embodiment. Can do.

  Moreover, although the said embodiment illustrated and demonstrated the case where the tilting operation of the cargo receiving stand 30 was guided with the guide roller 14, the guide roller 14 can also be abbreviate | omitted. For example, the operation amounts of both the drive devices 40 and 50 are synchronized with each other in a predetermined relationship, or the operations of both the drive devices 40 and 50 are fixed while the angle sensor detects the angle between the parallel link arm 21 and the load receiving platform 30. By synchronously controlling the relationship, the load receiving platform 30 can be operated in a fixed track.

  Furthermore, although the locking device for restraining the arm unit 20 is not particularly described in the above embodiment, for example, the link arms 28 and 29 of the parallel link arm 21 are fixed with hooks or the like in the retracted posture, or supported with the parallel link arm 21. It is also conceivable to provide a locking device for fixing the arm 22 and the like, and to provide means for fixing the cargo receiving platform 30 in the retracted position.

  Furthermore, in the above-described embodiment, the present invention is applied to the load receiving platform lifting / lowering device 100 that pulls the L-shaped load receiving platform 30 from the upright state (deployed posture) into the loading platform 3 while shifting the L-shaped receiving platform 30 to the retracted posture. The case where it is applied has been described as an example. However, for example, a load receiving platform lifting device that supports a cargo handling operation by moving the load receiving platform up and down between the ground and the loading platform is also applicable to other types of load receiving platform lifting devices. The invention is applicable. For example, a load receiving device lifting device (for example, see Japanese Patent Application Laid-Open No. 2010-155600) that lifts and lowers a horizontal load receiving device between the ground and the inside of the load carrier, and a load receiving device lifting device (for example, Japanese Patent Application Laid-Open No. 2005-289150), a retractable load receiving device lifting and lowering device (see, for example, Japanese Patent Application Laid-Open No. 2009-202667) that folds the load receiving table and slides it to the lower part of the vehicle frame, and rotates it upward without sliding the load receiving table. The present invention can also be applied to a rotary retractable cradle lifting and lowering device (see Japanese Patent Application Laid-Open No. 2010-52569) that is moved and stored in the lower part of the vehicle frame. Further, the present invention is not limited to storing the load receiving platform in the loading platform or the lower part of the vehicle frame, but various loading platform lifting devices (for example, Japanese Patent Application Laid-Open No. 2008-189189, Japanese Patent Application Laid-Open No. 2007) which store the loading reception stand in the rear portion of the loading platform. -331631, JP-A-2004-224082 and the like). Even in these cases, the same effects as the basic effects of the present invention can be obtained.

3 Cargo base 10 Base unit 20 Arm unit 30 Cargo base 31 Cargo body 32 Backrest 40 Lift drive device 50 Tilt drive device 61 Tank 62 Hydraulic pump 75 Low pressure relief valve 76 Low pressure relief conduit 77 Relief valve 79 for circuit protection Switching valve 90 Controller 100 Cargo stand lifting device Sgrd Ground sensor detection signal

Claims (3)

In a loading platform lifting device that supports loading and unloading of packages on a vehicle loading platform,
A base unit attached to the vehicle;
An arm unit connected to the base unit;
A receiving platform connected to the arm unit;
A double-acting lift driving device that drives the arm unit to raise and lower the load receiving table;
A grounding sensor that detects that the cargo cradle is grounded;
A hydraulic pump for supplying hydraulic oil to the lift driving device;
A tilt drive device that operates with hydraulic oil from the hydraulic pump to tilt and displace the load receiving table with respect to the arm unit;
A low pressure relief pipe which connects the discharge line and the tank of the hydraulic pump,
A low pressure relief valve provided in the low pressure relief line;
A switching valve provided in the low-pressure relief line;
Control means for driving the lift driving device and lowering the load receiving table while detecting the detection signal from the ground sensor and driving the tilt driving device together with the lift driving device to shift the load receiving table to an unfolded posture. And
Wherein, while the detection signal from the ground sensor when the receiving platform of the lowering operation has been input, receiving platform lifting device comprising a Turkey to open the switching valve. 2. The load receiving / lifting device according to claim 1 , wherein a relief pressure of the low pressure relief valve is lower than a relief pressure of a relief valve for circuit protection provided in a discharge pipe of the hydraulic pump. Stand lifting device. In the load receiving platform lifting apparatus according to claim 1 or 2,
The load receiving base is formed in an L shape by a back of the load receiving base body and a backrest erected on the main body of the load receiving base, and is pivotally supported by the arm unit at an L-shaped corner portion, and the load receiving base is supported by the tilt drive device. A load receiving table elevating device characterized in that it can be rotationally displaced between an upright position where the base body is leveled and a lying position where the backrest is laid down.

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