JP6026265B2 - Loading platform lifting device - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a load receiving platform lifting device used for loading and unloading a load between a vehicle loading platform and the ground, and more particularly to a load receiving platform lifting device including a load receiving platform capable of changing its posture from a horizontal state to a tilted state.

  The load receiving platform of the load receiving platform lifting / lowering device is maintained in a horizontal state during lifting and lowering in order to ensure the stability of the loaded cargo. On the other hand, when the load receiving platform descends to the lowest level and approaches or contacts the ground, there is one that is tilted so that the tip of the load receiving table is in contact with the ground. This is for avoiding the formation of a gap between the front end portion of the load receiving table and the ground so that the cargo (or cart) can be loaded and unloaded satisfactorily.

  Such downward tilting of the load receiving table lifting device is mainly performed by contraction of the hydraulic cylinder. For this reason, in the case where the hydraulic cylinder is not sufficiently depressurized during contraction, studies have been made focusing on the possibility of the hydraulic cylinder extending unexpectedly at the same time as the load is lowered and the load is eliminated. In other words, efforts are being made to prevent the phenomenon that the tip of the cargo cradle leaves the ground and the tip of the cargo cradle jumps as soon as the cart is lowered from the cargo cradle. This is because the tip of the cradle of the load receiving platform is caught on the end of the cart, and the collapse of the cargo may occur on the cart. In view of this, there is also introduced a loading platform lifting device that detects a tilt of the load receiving table and has a control for continuing the tilting posture based on the detection signal, and continues the tilting posture for a while even after the load is lowered. (Patent Document 1).

JP 2012-183910 A

  However, although the load receiving table lifting device according to Patent Document 1 has a great effect in terms of preventing the load receiving table from being flipped up, there is still room for improvement with respect to sensor mounting. This is because the mounting position of the sensor is limited in the consignment lifting device attached to the actual vehicle, and the difference in the mounting position greatly affects the durability of the sensor, the detection accuracy, the cost of mounting or maintenance, etc. is there.

  In the case of a load receiving platform lifting device in which the load receiving platform is lifted and lowered by the parallel link arm, the parallel link arm is supported so as to be rotatable up and down with respect to the vehicle frame of the vehicle. In order to avoid contact with the ground or an obstacle, the sensor is often provided on the base end side (side supported by the vehicle frame) of the parallel link arm.

  However, the base end side of the parallel link arm is a part below the loading platform and provided with an arm member, a hydraulic cylinder, electric wiring, and the like, and there are many space limitations. On the other hand, changing these layouts requires a great deal of cost.

  Further, when the sensor is attached to the load receiving platform lifting device already used, it is not preferable to remove the load receiving lift device from the vehicle because it increases the cost. Therefore, since the work is performed in a state where it is under the vehicle, a simple attachment work or attachment position is preferred. Furthermore, the higher the degree of request for the sensor attachment position, the lower the detection accuracy of the sensor when an attachment error occurs. Therefore, it is preferable that the degree of freedom of the attachment position is high. The same applies to the maintenance of the sensor.

  The present invention has been made in view of these points, can continue the downward tilting of the load receiving table, and can suppress the cost required for mounting, including the load receiving device lifting and lowering device that is already mounted on the vehicle. An object of the present invention is to provide a cargo receiving platform lifting device having a configuration.

  An arm body that is rotatably supported with respect to the vehicle frame, a load receiving base that is connected to the arm body and is lifted and lowered between the cargo bed and the ground, and a detection device that detects the arm body And a load receiving platform lifting device including a hydraulic drive device that tilts the load receiving table downward for a predetermined time. In this load receiving table lifting device, the arm body has a front / rear rotation part that can be separated from and attached to the vehicle frame when the load receiving table is tilted downward, and the detection unit or the detected part of the detection device is The vehicle is fixed to the vehicle frame so as to face the lower rotating portion of the rotating portion, and the downward tilting for the predetermined time is controlled by the detecting device. With the configuration in which the detection unit or the detected portion of the detection device is opposed to the lower rotation portion of the front / rear rotation unit, not only when the load receiving device lifting device is attached to the vehicle, but also the lifting operation of the load receiving device that is already attached to the vehicle. It can suppress that the attachment cost of detection apparatus itself raises also to an apparatus.

The vehicle frame includes a pair of left and right vertical frames whose longitudinal direction is the longitudinal direction of the vehicle, and a horizontal frame constructed on the vertical frame, and the detection unit and the detected unit are located behind the horizontal frame. It is good also as a structure provided.
The sensing unit or the sensed part of the sensing device may be arranged side by side so as to be adjacent to the arm body.

  In the load receiving platform lifting apparatus according to the present invention, the front / rear rotating portion rotates back and forth when the load receiving table is tilted downward. Therefore, if the lower rotating portion is used as a detected portion or a detecting portion, the load receiving platform lifting / lowering device is tilted downward. In various vehicles, the detection unit and the detected unit use a switching from “non-opposing state to facing state” or “opposing state to non-facing state” to continue the downward tilt of the load receiving table for a predetermined time. On the other hand, it can be realized stably.

  If the part facing the lower part of the rotation is the detection part or the detected part, the attachment work that is hidden under the vehicle is easy to reach. In addition, the electrical wiring and hydraulic piping of the vehicle are installed on a portion above the connection support portion between the arm body and the vehicle frame, for example, the vehicle frame, in order to avoid interference with obstacles or rocks below the vehicle. The For this reason, providing the detection unit or the like on the lower side of the rotation does not hinder the installation work of the detection device due to the electric wiring or the like installed on the vehicle frame. Therefore, it is not influenced by the skill level of the operator who installs the detection device.

  In addition, the detection part or the detected part is provided so as to face the lower rotation part of the front / rear rotation part of the arm body, because the front / rear rotation part forms a certain rotation area, Even if the mounting position is deviated, it is possible to detect the downward tilt of the load receiving platform. If the detection itself is possible, the downward tilting can be continued for a predetermined time by timer control or the like. That is, it is possible to continue the downward tilting of the load receiving table for a predetermined time without requiring a high level for the positional accuracy of mounting the detection device. In particular, when the pivot point of the front / rear rotation part is the upper part, the lower part of the rotation forms a long rotation area in the front / rear direction, so it is only necessary to install the detection part or the detected part in the part facing the lower rotation part. Stable detection operation is performed.

  Furthermore, when performing maintenance or the like, it is more efficient to mount a cargo box on the vehicle frame and to provide the detection unit or the detected unit on the lower side of the rotation. The same effect can be obtained when the detection unit is newly grounded to add a function to the load receiving table lifting device already used.

It is a perspective view of the load receiving table raising / lowering apparatus which concerns on embodiment of this invention. (A) is a side view of the load receiving table raising / lowering device according to the embodiment of the present invention, and (b) is a plan view of an essential part of an arm body of the device. It is a side view which shows the detection apparatus which concerns on embodiment of this invention. 1 is a circuit diagram of a hydraulic drive device according to an embodiment of the present invention. It is an electric circuit diagram of the load receiving table lifting apparatus according to the embodiment of the present invention. It is a flowchart figure of the downward movement operation | movement of the cargo receiving stand which concerns on this embodiment. It is a side view which shows the detection apparatus which concerns on another embodiment.

  An example of an embodiment of a load receiving table lifting apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a load receiving table elevating device 100 attached to the rear of the vehicle 1 and having a load receiving table 3 standing on the rear surface of the load box 2. The vehicle 1 is in a state where it can travel when in the state of the cargo cradle 3 in this figure.

  The load receiving platform lifting / lowering device 100 has a parallel link arm body 4 supported so as to be vertically rotatable with respect to the vehicle 1, and the load receiving platform 3 is supported at the tip of the arm body 4 so as to be vertically rotatable. ing. The arm body 4 is provided in a pair of left and right, and is supported by a vehicle frame that supports the cargo box 2 and the like on the respective base end sides. The vehicle frame includes a pair of left and right vertical frames (not shown) whose longitudinal direction is the longitudinal direction, and a horizontal frame 5 installed on the vertical frame. The cargo box 2 is mounted on the vertical frame, and the arm body 4 is connected to the horizontal frame 5. The arm body 4 includes a hydraulic cylinder and the like. This hydraulic cylinder is controlled to be expanded and contracted by a hydraulic drive device 6 provided on the lower left side of the cargo box 2. As the hydraulic cylinder expands and contracts, the arm body 4 is rotated up and down, and the load receiving platform 3 is moved up and down or tilted.

  The raising / lowering operation or tilting movement of the load receiving platform 3 will be described with reference to FIG. 2 including the configuration of the arm body 4 and the like. FIG. 2A is a side view of the load receiving table lifting apparatus 100, and FIG. 2B is a plan view centering on a connecting portion between the arm body 4 and the horizontal frame 5. FIG. Of the pair of left and right arm bodies 4, the arm body 4 on the left side of the vehicle will be described as a representative example.

  As described above, the vehicle frame includes the vertical frame 7 shown by a two-dot chain line and the horizontal frame 5 installed below the vertical frame 7. The arm body 4 is connected to the horizontal frame 5 through three support brackets 51a, 51b, 51c, and has an L-shape with a bracket (first frame bracket) 81 having a U-shaped cross section that opens downward. It is connected to the vertical frame 7 via a bracket (second frame bracket) 82 having a cross section.

  The three support brackets 51a, 51b, 51c are fixed in parallel with the horizontal frame 5 in an opposed state. Between the adjacent support brackets 51a to 51c, the base end portion of the constituent member of the arm body 4 is connected and supported so as to be rotatable up and down.

  Among these support brackets 51a to 51c, a first frame bracket 81 is fixed to a first support bracket 51a located on the innermost side in the vehicle width direction. The first frame bracket 81 is fixed in a state where the U-shaped cross section extends to the rear of the horizontal frame 5, and the second frame bracket 82 is fixed to the upper surface of the first frame bracket 81. The second frame bracket 82 is fixed to the vertical frame 7 side by side.

  A proximity sensor S is provided at the lower end portion of the first frame bracket 81 as a detection unit for detecting the rotation of the arm body 4. The proximity sensor S is attached via a sensor stay 81a. The sensor stay 81a is fixed to the first frame bracket 81 so as to extend downward. The proximity sensor S is inserted into the sensor stay 81a and is fixed in a state of facing the vehicle outer side.

  The arm body 4 includes a link arm 41 extending in the up-down direction, a lift arm 42, a lift cylinder 43, and a tilt cylinder 44 extending in the vehicle front-rear direction. The lift cylinder 43 and the tilt cylinder 44 are both hydraulic cylinders, and are provided so as to be able to supply and discharge pressure oil to and from the hydraulic drive device 6 (see FIG. 1).

  The link arm 41 is a bracket material having a U-shaped cross section that opens to the rear of the vehicle. The link arm 41 is positioned between the two support brackets 51a and 51b, and is connected to the support brackets 51a and 51b via the pin P1 so as to be able to rotate back and forth. Specifically, the upper portion 401 of the link arm 41 is supported by the pin P1, the lower portion 410 is the rotating tip side, and the rotating portion (hereinafter, the lower portion 410 is simply referred to as “rotating lower portion”). It is.

  The lift arm 42 has a base end portion (one end portion on the vehicle front side) rotatably connected to the upper end portion side of the link arm 41 via a pin P2. A front end portion (the other end portion on the rear side of the vehicle) of the lift arm 42 is rotatably connected via a pin P21 on the upper surface side (the left side in the drawing) at the rear end portion of the load receiving platform 3.

  The lift cylinder 43 is provided below the lift arm 42, and a base end portion (one end portion on the vehicle front side) is rotatably connected to a lower end portion of the link arm 41 via a pin P <b> 3. A tip end portion (the other end portion on the rear side of the vehicle) of the lift cylinder 43 is rotatably connected to a midway portion 42a of the lift arm 42 via a pin P32.

  The tilt cylinder 44 is provided below the lift arm 42, and a base end portion (one end portion on the front side of the vehicle) is rotatably connected to a support bracket 51b outside the vehicle via a pin P4. The front end portion (the other end portion on the rear side of the vehicle) of the tilt cylinder 44 is rotatably connected to the rear end portion of the load receiving platform 3 via a pin P41 on the lower surface side (the right side in the drawing).

  The load receiving platform 3 has a substantially triangular shape in side view. Rotation operation (arrow A1) for changing the posture of the upper surface (baggage placement surface) 31 to the horizontal state 3A and the lowering operation (arrow A2) for changing to the grounding state 3B while maintaining the horizontal posture with respect to the stand 3 ) And a downward tilt (arrow A3) from the state 3B in which the ground is grounded to the state 3C in which the tip of the load receiving table 3 is further grounded. When the load receiving platform 3 is raised or raised, the opposite operation is performed. These operations are performed by an operator operating an operating device (not shown) connected to the hydraulic drive device 6 (see FIG. 1).

  The rotation of the arrow A1 is performed by contracting the extended tilt cylinder 44. When the tilt cylinder 44 contracts, the load receiving table 3 rotates around the pin P21, and the upper surface 31 of the load receiving table 3 becomes horizontal at substantially the same height as the floor surface 21 of the load box 2 (see FIG. 1).

  The downward movement of the arrow A2 is performed by contracting the extended lift cylinder 43. When the lift cylinder 43 contracts, the lift arm 42, the lift cylinder 43, and the tilt cylinder 44 are rotated downward around the pins P2, P3, and P4, respectively. At this time, a parallelogram is formed by the pins P2, P3, P21, and P32, and the link arm 41, the lift arm 42, and the lift cylinder 43 form a parallel link via the pins P2, P3, P21, and P32. . Therefore, the load receiving platform 3 is lowered while maintaining the upper surface 31 in a horizontal state. In this lowering operation, the load receiving platform 3 and the load of the load are applied to the lift cylinder 43, and the force toward the vehicle front is applied to the link arm 41. Therefore, the link arm 41 is maintained in contact with the horizontal frame 5 as shown in FIG.

  The downward tilting of the arrow A3 is performed by further contraction of the lift cylinder 43 from the state 3B in which the load receiving platform 3 is grounded in a horizontal posture. When the load receiving platform 3 is in a grounded state 3B in a horizontal position, the lift cylinder 43 is further contracted by the downward load of the load receiving platform 3 and the like, and the pin P21 at the tip of the lift arm 42 is moved rearward of the vehicle. At this time, in the link arm 41, the rotating lower portion 410 moves rearward from the state in contact with the horizontal frame 5, and the rotating lower portion 410 is separated from the horizontal frame 5. That is, the link arm 41 is rotated rearward about the pin P1. Based on the operations of the lift cylinder 42 and the link arm 41, the load receiving platform 3 grounded in the horizontal posture is automatically switched to the state 3C tilted downward.

  The link arm 41 is detected by the proximity sensor S when the state is switched to the state 3 </ b> C tilted downward in the load receiving platform 3. The proximity sensors S are provided side by side in a state where the detection site is located between the gap W1 between the link arm 41 and the first frame bracket 81 so as to be adjacent to the link arm 41. The proximity sensor S is a detection range directed from the first frame bracket 81 toward the outside of the vehicle. Specifically, the link arm 41 that rotates so as to cross the detection range of the proximity sensor S is used as a detection target (detection target). Yes. Note that a cylindrical cover member C is attached to the vehicle inner portion (attachment portion to the sensor stay 81a) of the proximity sensor S. The cover member C can prevent damage caused by rocks while driving the vehicle, corrosion due to muddy water, and the like.

  Next, a method for detecting the link arm 41 of the detected part by the proximity sensor S of the detecting part will be described with reference to FIG. FIG. 3 is a side view of the link arm 41 and the first frame bracket 81 with the proximity sensor S as the center. For convenience of explanation, the lift arm 42, the lift cylinder 43, the tilt cylinder 44, or the pins P2 to P4 that support them are omitted as appropriate.

  While the load receiving table is raised and lowered in a horizontal posture, the link arm 41 is in a state of extending vertically as shown in FIG. At this time, the link arm 41 maintains substantially the same posture without crossing the detection range of the proximity sensor S (region directed to the outside of the vehicle).

  On the other hand, the link arm 41 rotates around the pin P1 to the rear of the vehicle (right side in the figure) as shown in FIG. At this time, as shown in the figure, the proximity sensor S is opposed to the rotating lower portion 410 of the rotated link arm 41, and the link arm 41 is detected by the proximity sensor S. When the proximity sensor S detects the link arm 41, the proximity sensor S outputs a signal to the hydraulic drive device 6. In response to this output signal, the downward tilt of the load receiving platform 3 is continued for a predetermined time. In the present embodiment, detection of the link arm 41 by the proximity sensor S is used as a trigger for the command to continue the downward tilt of the load receiving platform 3.

  As shown in FIG. 3B, the proximity sensor S is behind the horizontal frame 5 and is included in the rotation area of the link arm 41 as viewed from the side (area from the alternate long and short dash line to the solid line). Is provided. Even if the proximity sensor S is provided at any position in the rotation region, it can be detected in the same manner. In particular, since the detection target of the proximity sensor S is the lower rotation portion 410, the proximity sensor S only has to overlap with the range of the length L41 in the front-rear direction when viewed from the side. Therefore, even if the attachment position of the proximity sensor S is slightly shifted back and forth or up and down, the lower rotation portion 410 and the proximity sensor S can be made to face each other. In addition, the first frame bracket 81 to which the proximity sensor S is attached has a U-shaped cross section that opens downward and has a shape that extends rearward of the vehicle. Therefore, the degree of freedom of the attachment position of the proximity sensor S is high. When the width W41 (FIG. 3A) of the link arm 41 viewed from the side is increased, the link arm 41 is easily opposed to the proximity sensor S. Therefore, the degree of freedom of the attachment position of the proximity sensor S can be further increased. Further, if the attachment position of the proximity sensor S is within the rotation region of the link arm 41, the vehicle ground height is not lowered. Particularly, the attachment height of the proximity sensor S may be opposed to the rotated link arm 41 so long as it is at least within the range of the height H1 of the horizontal frame 5 because the link arm 41 contacts the horizontal frame 5. it can. Further, as long as the ground height of the vehicle can be prevented from being lowered, the proximity sensor S may be provided in the range of the height H2 up to the lower end of the link arm 41. And as for the attachment position of the proximity sensor S in the vehicle front-rear direction, it is desirable that it is provided at the rear of the horizontal frame 5 in terms of preventing interference with the rock. This is because the rear wheel of the vehicle 1 is located on the front side of the horizontal frame 5, so that the rock hits hardly interfere with the proximity sensor S.

  The attachment position of the proximity sensor S may be a position that can be opposed to the rotation region of the link arm 41 even if it is slightly deviated in the front-rear and up-down directions to the rear side of the horizontal frame 5. Since the detection of the link arm 41 by the proximity sensor S serves as a trigger for continuing the downward tilt of the load receiving table 3, even if the detection position is slightly deviated, if the timer is controlled based on the detection signal, the duration of the downward tilt is made constant. be able to.

  Since the proximity sensor S is attached to the first frame bracket 81 so as to face the rotating lower portion 410, it is easy to perform attachment work and maintenance from below. The first frame bracket 81 is provided side by side with the vertical frame 7 and has a cross-sectional shape that opens downward. The first frame bracket 81 can enter the space below the vertical frame 7 and the frame brackets 81 and 82 to perform the work. Maintenance work is not hindered by the body 4. In addition, electrical wiring and hydraulic piping connected to the arm body 4 are installed on the vehicle frames 5 and 7. This is to avoid contact with the arm body that rotates and interference with obstacles or rocks below the vehicle. Therefore, the configuration in which the proximity sensor S is attached to the lower side of the arm body 4 is efficient because the work is not hindered by electrical wiring or the like when performing the attachment work or maintenance. Such an effect can be obtained in the same manner even when a proximity sensor S is newly attached and a function is added to a load receiving table lifting apparatus that is already attached to a vehicle.

Further, the higher the accuracy required for the attachment position of the proximity sensor S, the more complicated the operation. In the configuration of the present embodiment, as described above, the “high degree of freedom of the attachment position” and “simple attachment work”. By making it possible to deal with various types of vehicles, it is possible to greatly contribute to the suppression of the installation cost of the proximity sensor S.
The downward rotation of the load receiving platform 3 and the detection by the proximity sensor S are performed by the hydraulic drive device 6 shown in FIG. 4 and the electric circuit shown in FIG.

  As shown in FIG. 4, the hydraulic drive device 6 includes an electric motor M, a hydraulic pump P, and an oil tank T. The pressure oil discharged from the hydraulic pump P is supplied to the lift cylinder 43 through the first pressure oil supply passage 61. Further, the lift cylinder 43 and the oil tank T can communicate with each other by a first pressure oil return path 62 branched from the first pressure oil supply path 61. Further, the tilt cylinder 44 and the hydraulic pump P can communicate with each other by a second pressure oil supply path 63 branched from the first pressure oil supply path 61, and the pressure oil discharged from the hydraulic pump P can be communicated with the tilt cylinder 44. It is the structure which can be supplied to. Further, the tilt cylinder 44 and the oil tank T can communicate with each other by a second pressure oil return path 64 connected to the first pressure oil supply path 63. Note that the control valves SOL1 to SOL3 shown in the figure are used to switch the communication or blocking of the pressure oil supply paths 61 and 63 and the pressure oil return paths 62 and 64.

  As shown in FIG. 5, the load receiving platform elevating device 100 includes an operating device that an operator commands to operate, an open / close relay 101 connected to the operating device, a driving conductor 102 that drives the hydraulic drive device 6, A driving relay 103 that drives the driving conductor 102, a timer 104 that sets the continuous operation time of the hydraulic drive device 6 to a predetermined time (for example, 20 seconds), and whether or not the attitude of the load receiving platform 3 has been changed to a horizontal state. And a shut-off relay 105 that maintains the switching valve SOL1 in the shut-off state upon detection of the sensor S10.

  The operating device includes an “open / close” switch B1 that changes the posture of the load receiving table 3 between a standing posture and a horizontal posture, an “up” switch B2 that raises the load receiving table 3, and a “lower” switch that lowers the load receiving table 3. A switch B3 is provided. When the “down” switch B 3 is pressed, no signal is output to the driving relay 103. Therefore, although the electric motor M is not driven, the switching valve SOL1 is in a communication state and the cargo receiving table 3 is lowered. If the posture of the load receiving platform 3 is not completely changed to the horizontal state, the shut-off relay 105 opens the contact R11 based on the detection of the sensor S10, the switching valve SOL1 is turned off, and the load receiving platform 3 is Does not descend.

  In such an electric circuit, the proximity sensor S provided on the first frame bracket 81 is connected to the downward tilt continuation relay 106. The timer 107 is controlled by the downward tilt continuation relay 106. The timer 107 controls the continuation state of the downward tilt of the cargo receiving platform 3. The control of the continuation state of the downward tilt is as shown in the flowchart of FIG.

  When the “down” switch B3 is pressed with respect to the horizontal loading tray 3, the loading tray 3 is lowered. If the “down” switch B3 is released halfway, the lowering operation stops (steps 1 to 3).

  In a state where the load receiving table 3 is in contact with the ground (step 4), when the “down” switch is further pressed, the tilting movement of the load receiving table 3 is started (steps 5 and 6). The rotation of the link arm 41 is detected by the proximity sensor S along with the tilting motion (steps 7 and 8). When the proximity sensor S detects the link arm 41, an electric signal is input to the tilt continuation relay 106, and the contact RB is closed. The timer 107 is activated by closing the contact RB. The contact T2 is kept closed for a predetermined set time (for example, 2 seconds) by the timer 107. While the closed state of the contact T2 is continued, the switching valve SOL1 is in the communication state regardless of whether the “lower” switch B3 is on or off (steps 9 and 10). That is, even if the operator releases the “down” switch B3 between steps 8 to 10, the downward tilt of the load receiving platform 3 can be continued. The predetermined set time for maintaining the downward tilt of the load receiving platform 3 is set so that the pressure relief associated with the contraction of the lift cylinder 43 is sufficiently performed during the downward tilt of the load receiving platform 3 over steps 6 to 10. The length can be changed as appropriate.

  Although a downward tilting continuation function is added to the load receiving platform lifting / lowering device 100, as shown in the flowchart of FIG. 6, the operator can continue the downward tilting by simply pressing the “down” switch B3. There is no need for a new operation for continuous control of tilting, and there is no need to feel the complexity of the work.

  Further, if the attachment position of the proximity sensor S is the lower end side of the first frame bracket 81 as in the present embodiment, the rotation area of the link arm 41 becomes longer in the front-rear direction, so the detection range of the proximity sensor S is the same. It can also be set longer in the front-rear direction. Therefore, the proximity sensor S can stably detect the downward tilt of the load receiving platform 3. In this case, the place where the vehicle 1 stops and the load receiving platform 3 descends is a place having an inclined ground or a step, and the lift cylinder 43 is hardly depressurized when the load receiving platform 3 is tilted downward. However, the downward tilt can be continued by the detection of the proximity sensor S.

  Note that the set time by the timer 107 is a time that the lift cylinder 43 is sufficiently depressurized after the tip of the load receiving table 3 is grounded, and the weight and size of the load receiving table 3 are set. Or can be set as appropriate in accordance with the assumed weight of the load. By using the load receiving table lifting device 100 that continues to tilt downward for the set time, even if the load is lowered from the load receiving table 3 and the lower load received by the load receiving table 3 is released by the load or the like, the tip of the load receiving table 3 Will not jump up.

  As described above, the link arm 41 is detected by the proximity sensor S for continuing the downward tilt of the load receiving platform 3, but the detected part is a member that is operated in accordance with the downward tilt of the load receiving platform 3. If there is, it may be other than the link arm 41.

  The member to which the proximity sensor S is attached is not limited to the first frame bracket 81. It is good also as a structure attached to the horizontal frame 5 as shown in FIG. For example, as shown in FIG. 7A, the proximity sensor Sa may be fixed to the lower portion of the horizontal frame 5, and the lower end portion 411a of the link arm 41a may be extended forward of the vehicle. In this case, the link arm 41a is in contact with the horizontal frame 5 before the load receiving platform 3 is tilted downward, and the lower end portion 411a and the proximity sensor Sa face each other. When the downward tilt of the load receiving platform 3 is started, the lower end 411a and the proximity sensor Sa are brought into a non-opposing state, and the continuous control of the downward tilting of the load receiving platform 3 is started by switching from the facing state to the non-opposing state.

  Further, as shown in FIG. 7B, a proximity switch Sb is attached to a fixed bracket 50b suspended downward from the rear surface 5b of the horizontal frame 5, and a lower end portion 411b extending downward in the link arm 41b is attached. It is good also as a structure made into the to-be-detected part. The proximity switch Sb has a detection range directed toward the rear of the vehicle, and is in a state of facing the lower end portion 411b as indicated by a one-dot chain line before tilting downward. When the downward tilting of the load receiving platform 3 is started, the lower end portion 411b is moved rearward and deviates from the detection range of the proximity sensor Sb. When the lower end portion 411b rotates from the detection range to the detection range, the continuation control of the downward tilt of the load receiving platform 3 is started. In addition, it is good also as a structure which provided the proximity sensor Sb in the rear surface 5b of the horizontal frame 5 by providing a notch in the front surface 410b of the link arm 411b.

  Further, although the proximity sensor S is attached and fixed to the first frame bracket 81, the same configuration as the configuration in which the proximity sensor S is attached to the link arm 41 and the detected portion fixed to the first frame bracket 81 is provided. An effect can be obtained. Further, regarding the detection unit, not only the proximity sensor but also other non-contact type sensors may be used, and for example, a contact type detection unit such as a limit switch may be used.

  The type of the cargo receiving platform lifting device is not limited to the configuration including the cargo receiving platform that stands up behind the cargo box 2 as in the present embodiment, and the same is true for the cargo receiving platform that is stored below the cargo box 2. Since an effect can be obtained, it is applicable.

  INDUSTRIAL APPLICABILITY The present invention is useful for all load receiving table lifting / lowering devices in which the load receiving table is tilted through a hydraulic cylinder.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Cargo box 3 Load receiving stand 4 Arm body 5 Horizontal frame 6 Hydraulic drive device 7 Vertical frame 41 Link arm (front-rear rotation part)
42 Lift arm 43 Lift cylinder 44 Tilt cylinder 410 Rotating lower part (detected part)
51a, 51b, 51c Support bracket 81 First frame bracket 82 Second frame bracket S Proximity sensor (detector)
100 Loading platform lifting device

Claims (3)

An arm body that is provided below the cargo box of the vehicle and is rotatably supported with respect to a vehicle frame that supports the cargo box ;
A load receiving platform connected to the arm body and being lifted and lowered between the loading platform and the ground, and tilted on the ground;
A detection device for detecting the arm body;
A hydraulic drive device that tilts the load receiving table downward for a predetermined time; and
With
The vehicle frame includes a vertical frame whose longitudinal direction is the longitudinal direction of the vehicle, and a horizontal frame whose longitudinal direction is the width direction of the vehicle below the vertical frame,
The horizontal frame is provided with a plurality of support brackets facing each other,
The arm body is connected to the support bracket in the opposed state so that the base end side of the arm body can be pivoted up and down, and can be separated from and connected to the horizontal frame when the load receiving table is tilted downward. Having a front and rear rotating part on the base end side ,
The detection part or the detected part of the detection device is in a state of being fixed with respect to the horizontal frame so as to face the rotation lower part of the front / rear rotation part,
The downward movement of the predetermined time is controlled by the detection device. Before Symbol detection unit and the detected portion includes receiving platform lifting apparatus according to claim 1, characterized in that provided in the rear of the transverse frame. The detection unit of the detection device is a proximity sensor, and is provided so as to be included in a rotation region of the front-rear rotation unit as viewed from the side of the vehicle. Loading platform lifting device.

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