JP3363050B2 - Safety device in operation control device of loading / unloading device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for a lifting and lowering device for a loading tray, wherein the loading tray is prevented from descending when the rotation restricting means is in a bridge mode. The present invention relates to a safety device in an operation control device of a lifting device. 2. Description of the Related Art A conventional loading tray lifting / lowering device is disclosed in Japanese Utility Model Laid-Open No.
As described in Japanese Patent Application Publication No. 543, when loading and unloading cargo between the cargo bed of the packing box and the ground, the rotation restricting means is switched to the horizontal mode, and the loading tray is horizontally extended from the vertical storage position. It is rotated to the position, and the loading tray is raised and lowered in that state. When loading and unloading cargo between a platform higher than the ground and slightly lower than the loading platform and the loading platform, the rotation restricting means is switched to a bridge mode, and the loading platform is rotated from the vertical storage position to the inclined extension position. The platform is moved so that the tip of the receiving platform abuts on the platform so that the platform can be bridged between the platform and the platform. [0004] In the above-mentioned conventional apparatus, when an operator stands on the receiving tray at the inclined protruding position in the bridge mode and intends to unload the platform from the loading platform to the platform. If another worker mistakenly lowers the loading tray, the loading tray changes from the inclined state to the platform side to the horizontal state, and then to the inclined state toward the platform. [0005] Then, the worker and the baggage on the receiving tray fall down to the loading platform side, and the worker may be injured and the baggage may be damaged. Therefore, an object of the present invention is to prevent the load receiving tray from lowering when the rotation restricting means is in the bridge mode. In order to achieve the above object, according to the present invention, a load receiving table provided at a rear portion of a vehicle body so as to be able to ascend and descend by driving a cylinder is configured such that the cylinder is reduced and lowered, and further rotated. The horizontal mode in which the restricting means restricts the loading table from rotating below the horizontal overhang position along the horizontal plane, and the rotation of the loading table to the inclined overhang position below the horizontal overhang position. In the operation control device of the loading / unloading device elevating device capable of selectively switching between the allowable bridge mode and the load receiving platform elevating device, a detection switch for restricting the lowering of the cylinder is provided when the rotation restricting means is in the bridge mode. I have. Embodiments of the present invention will be described below with reference to the drawings. B is a packing box mounted on the vehicle body F, and the packing box B is formed with a bed 1 on which a load is placed. At the rear of the vehicle body F, there is provided a loading tray lifting device TL called a so-called tail gate lifter. That is, at the rear of the vehicle body F, a pair of left and right elevating frames 2 is supported via a pair of left and right parallel link mechanisms L so as to be able to move up and down while maintaining a fixed posture (vertical posture in the illustrated example). between the parallel link mechanism L and the vehicle body F, the first hydraulic cylinder C ₁ is provided for vertically driving the elevator frame 2. Further, each of the left and right lifting frames 2 is pivotally supported so that a rectangular plate-shaped loading tray T can be turned up and down between an inclined extension position H ′ inclined downward with respect to a horizontal plane and a vertical storage position V. Between the receiving table T and the lifting frame 2, the receiving table T
The second hydraulic cylinder C ₂ is interposed for rotating the up and down. A horizontal mode M _H is provided between the lifting frame 2 and the loading table T to restrict or inhibit the rotation of the loading table T below the horizontal overhang position H along the horizontal plane. Stand T
A rotation restricting means A is provided which can be selectively operated to switch to a bridge mode M _H ′ that allows the lower part to rotate below the horizontal overhang position H. Each of the parallel link mechanisms L
Is a bracket FB fixed to the rear part of the vehicle body F, a pair of upper and lower link arms 3 ₁ , 3 ₂ pivotally supported by the bracket FB, and tips of the link arms 3 ₁ , 3 ₂ . are more configuration as elevator frame 2 is pivotally connected, respectively upper and lower, the first hydraulic cylinder C ₁ is interposed between the lower link arm 3 ₂ and the vehicle body F. Also in the elevator frame 2 at pivot coupling portion and coaxial with the upper link arm 3 ₁ lifting frame 2, receiving platform T is pivotally supported 5 ₁ to be vertically rotated. Each lifting frame 2 includes a pair of left and right side plates 2s, 2s
And a cylindrical connecting pin 2p for integrally connecting the upper portions of both side plates 2s and 2s.
The pivot 5 ₁ passing through the p, is supported freely base frame 4 and the upper link arm 3 ₁ rotates each receiving platform T, whereas, both side plates 2s, is between the bottom of the 2s, lower link arm 3 ₂ the distal end tube portion of the is rotatably supported via a pivot 5 _2. A stopper plate S that can be engaged with and disengaged from a later-described regulating block 6 is fixed between the lower left and right sides of the left and right plates 2s and 2s. A regulating shaft 7 extending over the full width of the receiving table T is rotatably fitted to and supported by the base frame 4 of the receiving table T. An operation lever 7a for manually rotating the actuator 7 is integrally connected. Further, on the regulating shaft 7, regulating blocks 6 are respectively fixed so as to correspond to the left and right lifting frames 2 (stopper plates S). When the control block 6 is in the horizontal mode _MH , as shown in FIG.
The stopper plate S for restricting the pivot plate from rotating downward.
The free end of the block 6 is engaged with the stopper 6, and when the bridge mode M _H ′ is in place as shown in FIG. The side surface of the block 6 faces the plate S. The restricting block 6 and the restricting shaft 7 with the operating lever 7a constitute a rotation restricting means A. A normally open limit switch 9 which is a detection switch is provided on the lifting frame 2 via a bracket 8, while an operating piece 10 is provided on a regulating shaft 7 corresponding to the limit switch 9. By contrast, the operation piece 10 may be provided on the lifting frame 2 and the limit switch 9 may be provided on the regulating shaft 7.
Referring next to the hydraulic circuit of FIG. 5, the hydraulic oil sent from the oil tank 12 by the hydraulic pump 11 is an oil passage 14 communicating with the first cylinder C ₁ through the first check valve 13
When, is branched into an oil passage 16 that communicates with the second cylinder C ₂ through the second check valve 15. In the middle of the oil passage 14, the first solenoid 1
7, an oil passage 20 having a first switching valve 18 and a throttle valve 18 and communicating with the oil tank 12 is branched, and is switched in the middle of the oil passage 16 by excitation of a second solenoid 21. Oil passage 2 having second switching valve 22
The oil passage 23 is connected to the oil passage 20 between the first switching valve 18 and the throttle valve 19. In addition, 2
4 is a relief valve. Next, the electric circuit shown in FIG. 6 will be described. Reference numeral 25 denotes a first circuit which is connected between the main circuits 26 and 26 and has a relay switch r and an electric motor M interposed on the way. Reference numeral 27 denotes a second circuit having one end connected to the main circuit 26 and the other end connected to the remote control switch 28. Reference numeral 29 denotes a third circuit having one end connected to the ascending side U of the remote control switch 28 and a relay R interposed on the way. Reference numeral 30 denotes a fourth circuit having one end connected to the lower side D of the remote control switch 28 and the second solenoid 21 interposed on the way. Reference numeral 31 denotes a fifth circuit having one end connected to the fourth circuit 30 on the upstream side of the second solenoid 21 and having the normally open limit switch 9 and the first solenoid 17 interposed therebetween. The normally open limit switch 9 remains open when the rotation restricting means A is switched to the bridge mode M _H ′ to set the load receiving table T to the inclined extension position H ′.
The energization of the solenoid 17 is regulated, and when the rotation restricting means A is switched to the horizontal mode _MH to set the loading tray T to the horizontal extension position H, it is switched by the operating piece 10 to be closed, and the first is closed. Energization of the solenoid 17 is allowed. In the embodiment of the present invention, the loading tray is raised and lowered via the parallel link mechanism. However, the loading tray may be vertically raised and lowered along the column. The limit switch is normally open, but when the limit switch is normally closed and the rotation restricting means is switched to the bridge mode and the load receiving tray is set to the inclined projecting position, it is switched by the operating piece and opened, and the first solenoid is opened. The power supply to the power supply may be regulated. Although the limit switch is provided on the lifting frame, the limit switch may be provided on the base frame of the load receiving table so as to restrict the power supply to the first solenoid when the rotation restricting means is in the bridge mode. Good. The rotation restricting member provided with the operation piece is mounted on the base frame of the loading tray. When the rotation restricting member is mounted on the lifting frame and the rotation restricting means is in the bridge mode, the rotation of the first solenoid is restricted. It may be. The operation of the present invention having the above-described structure will now be described. When carrying in / out the cargo between the cargo bed 1 of the cargo box B and the ground G, first, the rotation restricting means A is switched to the horizontal mode _MH . Thereafter, when the remote control switch 28 is switched to the descending side D, the second solenoid 21 is excited and the second switching valve 22 is switched. Then, the second hydraulic cylinder C
_{The second} hydraulic oil is supplied to the oil tank 12 via an oil passage 23 provided with a second switching valve 22 and an oil passage 20 provided with a throttle valve 19.
And the second hydraulic cylinder C ₂ contracts and the receiving table T
Pivots downward from the vertical storage position V to the horizontal overhang position H where the free end of the restriction block 6 engages with the stopper plate S. In this state, the load on the loading platform 1 is placed on the receiving platform T. The operation piece 10 comes into contact with the limit switch 9 due to the downward rotation of the loading tray T, and the limit switch 9 is switched from normally open to closed. When the remote control switch 28 is switched to the lower side D, the first solenoid 17 is excited via the limit switch 9 and the first switching valve 18 is switched. Then, the hydraulic oil of the first hydraulic cylinder C ₁ is supplied to the oil tank 1 via an oil passage 20 provided with a first switching valve 18 and a throttle valve 19.
Is refluxed in 2, receiving platform T by the first hydraulic cylinder C ₁ is reduced is lowered while maintaining the horizontal overhang state to the lowered position from the elevated position. The luggage on the receiving tray T is dropped on the ground G. Next, another load on the ground G is placed on the receiving tray T. When the remote control switch 28 is switched to the ascending side U, the relay R is excited, the relay switch r is turned on, and the electric motor M operates. Then, the hydraulic pump 11 is operated, and the hydraulic oil from the oil tank 12 is supplied to the first check valve 13 and the oil passage 1.
4 to the first hydraulic cylinder C ₁ , the second check valve 15 and the second hydraulic cylinder C ₂ via the oil passage 16, respectively. the hydraulic cylinder C ₁ is in the first hydraulic cylinder C ₁ since the large first pressure-receiving area of the hydraulic cylinder C ₁ to extend above elongation increases receiving platform T from the lowest position,
When the loading tray T is substantially flush with the loading platform 1, the remote control switch 28 is moved away from the rising side U to stop the operation of the electric motor M. Then, the load on the loading tray T is placed on the loading platform 1. Next, when carrying in / out the cargo between the loading platform 1 and the platform PH, the rotation restricting means A is switched to the bridge mode M _H ′. Thereafter, when the remote control switch 27 is switched to the lower side D, the second solenoid 21 is excited and the second switching valve 22 is switched. Then to be allowed to rotate up to below the horizontal overhanging position H is receiving platform T by the second hydraulic cylinder C ₂ is reduced from the vertical storage position V, receiving platform T at its distal end platform H It descends to the inclined overhang position H '. At this time, the side surface of the restriction block 6 faces the stopper plate S. In this state, the load on the loading platform 1 is lowered onto the platform PH through the loading platform T, or another package on the platform PH is loaded on the loading platform 1 via the loading platform T. If another worker mistakenly operates the remote control switch 28 to the lower side D while the worker is carrying the load on the loading tray T, the operating piece 10 does not contact the limit switch 9 and switch 9 remains deenergized not energized in the first solenoid 17 so remains normally open, without first switching valve 18 is switched, receiving platform and the first hydraulic cylinder C ₁ is reduced T does not fall. As described above, according to the present invention, when the rotation restricting means is in the bridge mode, the lowering of the cylinder is restricted by the detection switch, so that the load is carried in and out between the platform and the platform. When another worker mistakenly attempts to lower the cradle, the cradle does not lower.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall view of the present invention. FIG. 2 is a perspective view of a main part in a state where the receiving table is at an inclined projecting position. FIG. 3 is a view as viewed in the direction of the arrow X in FIG. 2; FIG. 4 is a perspective view of a main part in a state where the loading tray is at a horizontally extended position. FIG. 5 is a hydraulic circuit diagram. FIG. 6 is an electric circuit diagram. [Description of Signs] 9 Limit switch A as a detection switch A rotation restricting means C ₁ First hydraulic cylinder F Body H Horizontally extended position H 'Inclined extended position M _H Horizontal mode M _H ' Bridge mode T Receiving table TL Receiving Table lifting device

Claims (1)

(1) Claims 1. A load receiving table provided at a rear portion of a vehicle body so as to be able to move up and down by driving a cylinder, the cylinder contracts and descends. Select either a horizontal mode that restricts rotation below the horizontal overhang position along the horizontal axis, or a bridge mode that allows the loading tray to rotate to an inclined overhang position below the horizontal overhang position. In the operation control device of the loading / unloading device which can be switched to a safety device, the safety device in the operation control device of the loading / unloading device which comprises a detection switch for restricting the lowering of the cylinder when the rotation restricting means is in the bridge mode. .