JP5701105B2 - Loading platform lifting device - Google Patents

Description

  The present invention relates to a load receiving platform lifting apparatus, and more particularly to a load receiving platform lifting apparatus having a load receiving platform that can be moved up and down and tilted.

  2. Description of the Related Art Conventionally, a load receiving table lifting device that lifts and lowers a load receiving table provided at the rear of a vehicle is known. Such an elevating device is disclosed in, for example, Japanese Patent Laid-Open No. 2001-233114 (Patent Document 1).

  In the load receiving platform elevating device described in Patent Document 1, the load receiving platform (gate 6) is lowered from the floor height of the loading platform to the height at which the load receiving platform is grounded while maintaining the horizontal state of the upper surface (mounting surface 61). The load receiving platform has a triangular shape when viewed from the side, and when the load receiving platform comes in contact with the ground, the front end side (the vehicle rear side) of the load receiving table floats from the ground. Therefore, after the load receiving platform is grounded, the load receiving platform is tilted (tilted), and the tip of the load receiving platform is grounded (this operation is referred to as “tilting” in this specification).

  In the load receiving table elevating device, the operation (elevating and tilting) of the load receiving table is performed based on the expansion and contraction of the hydraulic cylinder. The expansion and contraction of the hydraulic cylinder is performed by the operator pressing the operation button of the input device (remote control). While the operator pushes the operation button, the cargo cradle operates, and when the worker releases the operation button, the cargo cradle stops.

JP 2001-233114 A

  In the load receiving platform elevating device described in Patent Document 1, there is no problem if the operator releases the operation button after the load receiving platform is grounded and the tip of the load receiving platform is securely grounded to a desired state. However, if the operator immediately releases the operation button after the load receiving platform tip is grounded, the load receiving platform tip may not be grounded to a desired state. When the tip of the load receiving platform is grounded, the hydraulic cylinder is contracted and the pressure in the hydraulic cylinder is released, but if the operation button is released immediately after the tip of the load receiving platform is touched, the contraction or pressure release becomes insufficient. End up. The load receiving platform is pressed downward (on the ground side) by the weight of the loaded load or the like. As a result, even if the hydraulic cylinder is not contracted or depressurized, the tip of the load receiving platform is grounded at first glance, but the tip of the load receiving platform jumps up due to the reaction of releasing the pressure as soon as the load is lowered.

  In many cases, a cart or the like is used for loading and unloading the load, and the above-described jumping of the tip of the load receiving table occurs when the caster of the cart is lowered, and the tip of the load receiving table may interfere with the rear end of the cart.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a load receiving table lifting device capable of reliably preventing the phenomenon that the tip of the load receiving table jumps up. .

A load receiving platform lifting apparatus according to the present invention includes a support member installed along a vehicle width direction with respect to a vehicle frame, a shaft portion provided on the support member along a vehicle width direction, and a shaft portion. rotatably on the axially supported by the rotating member, and the loading dock which can be tilted on the ground base while lifting between the cargo and the ground, pivotally attached to the rotating member, receiving platform groups The arm which supports an edge part, the drive system which tilts a load receiving stand, and the sensor which detects the tilt of a load receiving stand are provided. When the sensor detects tilting of the load receiving table in the direction of grounding the tip of the load receiving table, the drive system continues to tilt the load receiving table in the direction of grounding the tip of the load receiving table for a predetermined time. The detection of the tilt of the load receiving table in the direction in which the front end portion of the load receiving table is grounded is performed when the sensor detects the rotation of the rotating member.

  In this specification, “detecting the tilt of the load receiving table” means both detecting at the moment when the load receiving table starts to tilt and detecting the movement after the load receiving table starts to tilt. Including.

  Further, in the present specification, “continuing tilting of the receiving platform” means that the tilting is continued regardless of whether or not a signal for tilting the receiving platform is input from the input unit.

  In one embodiment, the cargo receiving platform lifting device includes an input unit through which an operator inputs a signal for operating the drive system. When the input unit is turned on while the loading platform is lowered from the loading platform level to the ground level, the drive system starts to tilt the loading platform in the direction in which the tip of the loading platform is grounded. .

  According to the present invention, in the load receiving table lifting device, it is possible to reliably prevent the phenomenon that the tip of the load receiving table jumps up.

It is a schematic diagram which shows roughly operation | movement of the load receiving table raising / lowering apparatus which concerns on one embodiment of this invention. It is a side view of the load receiving table raising / lowering apparatus which concerns on one embodiment of this invention. It is a figure which shows the state from which the cargo receiving stand began to tilt from the state of FIG. It is a figure which shows the state in which the load receiving stand tilted from the state of FIG. 3 until the front-end | tip part of a load receiving stand contacts. It is a figure which shows an example of schematic structure of the hydraulic drive unit in the load receiving table raising / lowering apparatus which concerns on one embodiment of this invention. It is a figure which shows an example of the electric circuit of the load receiving table raising / lowering apparatus which concerns on one embodiment of this invention. It is a flowchart for demonstrating the descent | fall operation | movement of the load receiving platform raising / lowering apparatus which concerns on one embodiment of this invention, and the subsequent tilting operation | movement.

  Embodiments of the present invention will be described below. Note that the same or corresponding portions are denoted by the same reference numerals, and the description thereof may not be repeated.

  FIG. 1 is a schematic diagram schematically showing the operation of the load receiving platform lifting apparatus 10 according to the present embodiment. The load receiving platform lifting / lowering device 10 is provided with a load receiving stand 5 that is rotatable in the direction of an arrow DR1 at the rear portion of the vehicle. The loading platform 5 moves up and down in the direction of the arrow DR2 while maintaining a horizontal state between the height of the loading platform 100 and the ground. The load receiving platform 5 descending from the height of the loading platform 100 and touching the ground tilts (tilt operation) in the direction of the arrow DR3 so as to ground the tip. By tilting the load receiving stand 5, it is possible to easily load and unload the load on the load receiving stand 5.

  In the state of FIG. 2, the proximal end portion 51 of the load receiving platform 5 is in contact with the ground contact surface G, but the distal end portion 52 of the load receiving platform 5 is separated from the ground contact surface G. At this time, the upper surface of the receiving tray 5 is substantially horizontal.

  The configuration of the cargo receiving platform lifting apparatus 10 will be described with reference to the side view shown in FIG. The load receiving platform elevating device 10 includes a tilt arm 2 assembled to the frame 1 so as to be rotatable with respect to the frame 1 of the chassis, and a lift arm 3 assembled to the tilt arm so as to be rotatable with respect to the tilt arm 2; A lift cylinder 4 provided between the tilt arm 2 and the lift arm 3, a load receiving platform 5 supported by the lift arm 3, and a sensor 6 that detects the rotation of the tilt arm 2 are included. Note that the frame 1 has a shape extending in the vehicle body width direction, is installed at the rear ends of a pair of left and right chassis frames SF extending in the vehicle body longitudinal direction, and is provided as a support member for fixing the tilt arm 1 and the like.

  The tilt arm 2 is supported by the frame 1 via a support bracket 11 fixed to the frame 1 so as to be rotatable by a rotation shaft (pin) 2A. The tilt arm 2 is formed in a substantially L-shaped cross section, and a rotating shaft 2A is provided in the vicinity of the bent portion of the L-shape.

  The lift arm 3 extends in the front-rear direction of the vehicle body, and a front end thereof is rotatably connected to the tilt arm 2 and a rear end thereof is rotatably connected to the cargo receiver 5. The lift cylinder 4 is a hydraulic cylinder and is provided below the lift arm 3. The front end of the lift cylinder 4 is rotatably connected to the lower end of the tilt arm. The rear end of the lift cylinder 4 is rotatably connected to the lift arm 3. When the lift cylinder 4 is extended, the load receiving platform 5 is raised, and when the lift cylinder 4 is contracted, the load receiving platform 5 is lowered. When the lift cylinder 4 is further contracted in a state where the load receiving platform 5 is grounded, the load receiving platform 5 is tilted in a direction in which the tip end portion 52 is grounded.

  As the sensor 6, for example, a proximity sensor is used. In addition, as a modified example of the sensor, for example, an optical detection type including a transmitting unit and a receiving unit installed so as to be arranged in the width direction of the vehicle can be considered. In this case, the sensor can detect whether or not the tilt arm 2 is rotated depending on whether a signal (for example, infrared rays or light) from the transmission unit reaches the reception unit.

  FIG. 3 shows a state in which the load receiving platform 5 starts to tilt from the state of FIG. 2, and FIG. 4 shows a state in which the load receiving platform 5 tilts until the tip 52 of the load receiving platform 5 comes into contact with the ground.

  By tilting the load receiving platform 5 so that the tip 52 of the load receiving platform 5 approaches the ground contact surface G, the tilt arm 2 rotates clockwise about the rotation shaft 2A. In FIG. 3, a portion 21 extending downward from the rotation shaft 2 </ b> A is rotated by an angle θ in a direction away from the frame 1. In the downward movement until the base end portion 51 of the load receiving platform 5 is grounded, the tilt arm 2 does not rotate and remains in the state shown in the enlarged view of FIG. When the tilt arm 2 rotates by an angle θ, a part of the portion 22 extending forward approaches the sensor 6 (α portion in FIG. 3). As a result, the sensor 6 detects that the tilt arm 2 has started to rotate, that is, the load receiving platform 5 has started to tilt.

  As shown in FIG. 4, when the load receiving platform 5 further tilts and the tip of the load receiving platform 5 comes into contact with the grounding surface G, the portion 21 extending below the tilt arm 2 rotates by an angle larger than the angle θ.

  FIG. 5 is a diagram illustrating an example of a schematic configuration of a hydraulic drive device in the cargo receiving platform elevating device 10. A power unit (P / U) 100 as a “hydraulic drive device” includes an electric motor (prime mover) 110, a hydraulic pump 120 driven by the electric motor 110, an oil tank 130 provided on the suction side of the hydraulic pump 120, A pressure oil supply passage 140 that supplies pressure oil discharged from the hydraulic pump 120 to the lift cylinder 200 (corresponding to the lift cylinder 4 in FIG. 2), a check valve 140A provided in the pressure oil supply passage 140, a pressure A pressure oil return passage 150 that is branched downstream of the check valve 140A in the oil supply passage 140 and communicated with the oil tank 130; and a switching valve 150A that can switch the flow of the pressure oil return passage 150 to a communication / blocking state. A flow valve 150B provided on the downstream side of the switching valve 150A, a relief valve 160 that regulates the maximum value of the discharge pressure of the hydraulic pump 120, Pressure for supplying pressure oil to an open / close cylinder 300 (not shown in FIG. 1) that branches off upstream of the check valve 140A in the oil supply passage 140 and opens and closes the load receiving platform (arrow DR1 in FIG. 1). An oil supply passage 170, a switching valve 170A capable of switching the flow of the pressure oil supply passage 170 to a communication / blocking state, a throttle valve 170B provided upstream of the switching valve 170A, and a switching valve in the pressure oil supply passage 170 A pressure oil return passage 180 connected to the downstream side of 170A, a switching valve 180A capable of switching the flow of the pressure oil return passage 180 to a communicating / blocking state, and a throttle valve 180B provided on the downstream side of the switching valve 180A, including. The power unit 100 having this configuration functions as a drive system for raising and lowering and tilting the load receiving platform 5.

  When the hydraulic pump 120 is driven by the electric motor 110 and the flow of the pressure oil return passage 150 is blocked by the switching valve 150A, the pressure oil discharged from the hydraulic pump 120 is lifted via the pressure oil supply passage 140 through the lift cylinder 200. To be supplied. Thereby, the lift cylinder 200 is driven in the extending direction, and the load receiving platform 5 is raised.

  On the other hand, when the switching valve 150A is switched to the communication position with the electric motor 110 and the hydraulic pump 120 stopped, the pressure oil from the lift cylinder 200 flows out to the oil tank 130 via the pressure oil return passage 150 due to gravity. Then, the lift cylinder 200 is driven in the contraction direction. As a result, the cargo receiving platform 5 is lowered. If driving of the lift cylinder 200 in the contraction direction is continued in a state where the load receiving platform 5 is grounded, the load receiving platform 5 is tilted in a direction in which the tip end portion is grounded.

  In addition, when the hydraulic pump 120 is driven by the electric motor 110, when the switching valve 170 </ b> A is in the communication state and the switching valve 180 </ b> A is in the cutoff state, the pressure oil discharged from the hydraulic pump 120 passes through the pressure oil supply passage 170. Are supplied to the open / close cylinder 300, and the open / close cylinder 300 is driven in the extending direction. Thereby, the load receiving stand 5 is rotated to a closed state (the load receiving stand 5 is closed).

  On the other hand, when the electric motor 110 and the hydraulic pump 120 are stopped, and at the same time, the switching valve 180A is switched to the communication state and the switching valve 170A is switched to the shut-off state, the pressure oil from the open / close cylinder 300 is pulled by the gravity. The oil flows out into the oil tank 130 through 180, and the open / close cylinder 300 is driven in the contraction direction. As a result, the cargo cradle 5 rotates to the open state (the cargo cradle 5 opens).

  FIG. 6 is a diagram illustrating an example of an electric circuit of the load receiving platform lifting apparatus 10 according to the present embodiment. In addition to the switching valves and the electric motor 110 described above, the load receiving platform lifting / lowering device 10 includes a remote controller 410 capable of operating the lifting / lowering (up / down) and opening / closing of the load receiving platform 5 from the outside of the load platform, and an “open / close” switch of the remote control 410. The open / close relay 510 connected to the P / U drive conductor 520 for driving the power unit 100, the drive relay 530 for driving the P / U drive conductor 520, and the continuous operation time of the power unit 100 are set to a predetermined value. Based on the detection result of the timer 540 for regulating within time (for example, 20 seconds), the sensor 610 which detects that the receiving stand 5 is not in the fully open position, and the sensor 610, the receiving stand 5 is completely When not in the open position, it further includes a cutoff relay 620 for maintaining the switching valve 150A in the cutoff state.

  When the “down” switch of the remote controller 410 is pressed, the drive command signal (electrical signal) is not input to the drive relay 530 and the electric motor 110 is not driven, but the switching valve 150A is brought into the communication state, and the load receiving platform 5 Descends. Note that when the load receiving platform 5 is not in the fully open position, the switching relay 150A opens the contact R1-1 based on the detection result of the sensor 610, so that the switching valve 150A is shut off. Even if the “down” switch of the remote controller 410 is pressed, the cargo receiving platform 5 does not descend.

  In the load receiving table elevating device 10, the operation of lowering the load receiving table 5 and tilting is performed according to the procedure shown in the flowchart of FIG. When the “down” switch is pressed and the base end portion 51 of the load receiving platform 5 is grounded, the operator determines that the lowering operation has been completed. Note that when the operator releases the “down” switch to turn it off, the descending operation of the load receiving platform stops.

  Next, when moving to the tilting operation, the operator presses the “down” switch to turn it on. As a result, the tilting operation is started, and the rotation of the tilt arm 2 is detected by the sensor 6 (enlarged view in FIG. 3), and the sensor 6 detects the start of tilting of the load receiving platform 5. At this time, an electrical signal is input to the tilt continuation relay 6A, the contact RB that is normally open is closed, and the timer 6B is operated via the contact RB. As a result, the contact T2 that is normally open is closed for a predetermined time (for example, 2 seconds), and the switching valve 150A is brought into communication regardless of whether or not the “lower” switch of the remote controller 410 is turned on. The With respect to this predetermined time, a time t1 required from when the sensor 6 starts detection until the front end 52 of the load receiving platform 5 is grounded, and a minute time after the front end 52 is grounded (at least approximately the same time as t1). ) Means the sum of t2. Therefore, the remote controller can be used in a state where the tip 52 of the cargo cradle 5 is not grounded or in a state where the tip 52 is not sufficiently pressed against the ground even when grounded, that is, the cargo cradle 5 is not tilted reliably. Even if the “down” switch 410 is turned off, the load receiving platform 5 continues to tilt until the tip of the load receiving platform 5 reaches a state where it is securely grounded to the ground surface. As a result, the lift cylinder 4 (200) is in a desired contracted state and is in a desired pressure-removed state in the lift cylinder 4 (200), so that the load loaded on the load receiving platform 5 is lowered and the load received by the load receiving platform 5 Even if the downward pressing due to the weight is released, the tip of the load receiving platform 5 does not jump up.

  In the above example, the structure in which the load receiving platform 5 rotates in the direction of the arrow DR1 (see FIG. 1) with respect to the chassis has been described, but the load receiving platform 5 is folded instead of opening and closing by the rotation in the arrow DR1 direction. Needless to say, the above-described idea (sensor 6 or the like) in the aspect of tilting (arrow DR3) can be applied even if the structure is slid and stored in the lower part of the chassis.

  The configuration in which the tilt related to the load receiving table lifting device 10 is continuously performed for a predetermined time functions in the tilting operation after the completion of the lowering operation of the load receiving table 5. Can be secured. Control in which the tilt of the receiving platform 5 is continued even when the “down” switch of the remote controller serving as the input unit is not pressed is performed after the operator recognizes that the tilting operation is performed. That is, since the detection by the sensor 6 is not performed while the load receiving platform 5 is in the descending operation, the continuous operation of the load receiving platform 5 as described above does not occur, and the downward movement is not unexpectedly shifted to the tilting operation.

  Further, since it is only necessary to press the “down” switch, there is no change in the operation method for lowering or tilting the load receiving platform 5, and the operator does not feel bothered.

  In the above-described load receiving platform elevating device 10, the power unit 100 forming the drive system for moving the load receiving platform 5 up and down and tilting is configured to start the tilting operation by pressing the “down” button (see FIG. 7). It is good also as a structure which tilts the receiving stand 5 with a method. For example, if the “down” switch is kept pressed when the descending operation of the cargo receiving platform 5 is completed, the structure may be able to continuously shift to the tilting operation. In this case, the operator does not have to operate the “down” switch a plurality of times.

  In addition, regarding on / off switching with the “down” switch, the switch is switched from on to off by releasing the switch, but switching from “on to off” or “off to on” by pressing the switch. In other words, it is possible to adopt a configuration that does not turn off just by releasing the switch. In this case, when performing the lowering operation, if the load receiving platform elevating device continuously performs the tilting operation by pressing the “down” switch, the input (signal transmission) for starting the tilting operation is not required. Can do.

  On the other hand, in order to shift to the tilting operation, a new tilting command may be required at an input unit different from the “down” switch.

  Regarding the detection of the tilt by the sensor 6, not only the detection is started when the tilt arm 2 is rotated by the angle θ, but it may be coincident with the start time of the tilt (the rotation start time of the tilt arm 2). Or you may set so that detection is possible in the state where the base end 51 of the load receiving platform 5 is grounded.

  The sensor 6 is not limited to the structure attached to the frame 1, and may be a grounding sensor that is provided near the base end portion 51 of the load receiving platform 5 and detects that the base end portion 51 is grounded. In this case, the tilting operation is continued on condition that the detection by the ground sensor and the tilting command are output to the input unit.

  Although the embodiments of the present invention have been described above, the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 frame, 2 tilt arm, 2A rotating shaft, 3 lift arm, 4 lift cylinder, 5 load receiving platform, 6 sensor, 6A tilting continuation relay, 6B timer, 10 load receiving platform lifting device, 100 power unit, 110 electric motor, 120 Hydraulic pump, 130 oil tank, 140 pressure oil supply passage, 140A check valve, 150 pressure oil return passage, 150A switching valve, 150B flow valve, 160 relief valve, 170 pressure oil supply passage, 170A switching valve, 170B throttle valve, 180 pressure oil return passage, 180A switching valve, 180B throttle valve, 200 lift cylinder, 300 open / close cylinder, 410 remote control, 510 open / close relay, 520 power unit drive conductor, 530 drive relay, 540 timer, 610 sensor, 620 shut-off relay .

Claims (2)

A support member constructed along the width direction of the vehicle with respect to the vehicle frame;
A shaft provided on the support member along the width direction of the vehicle;
A pivot member pivotally supported by the shaft portion;
And receiving platform which can be tilted on the ground while lifting between the cargo and the ground,
An arm that is pivotally attached to the pivot member and supports a base end of the load receiving table;
A drive system for tilting the load receiving table;
A sensor for detecting the tilt of the load receiving table ,
When the sensor detects a tilt of the load receiving base in a direction in which the front end of the load receiving base is grounded, the drive system tilts the load receiving base in a direction to ground the front end of the load receiving base over a predetermined time. It was allowed to continue,
Detection of tilting of the load receiving table in a direction in which the tip of the load receiving table is grounded is performed by detecting the rotation of the rotating member by the sensor . An input unit through which an operator inputs a signal for operating the drive system;
When the input unit is turned on while the load receiving table is lowered to the level of the ground, the drive system starts to tilt the load receiving table in a direction in which the tip of the load receiving table is grounded. The load receiving table elevating device according to claim 1.

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