Loading platform lifting device

Abstract

To provide a load receiving table lifting device which can inhibit a load receiving table from flapping due to swinging occurring when a vehicle travels.SOLUTION: A load receiving table lifting device includes: a load receiving table 2 on which loads are placed; a lifting mechanism B which moves up or down the load receiving table 2; a load receiving table support part C which supports the load receiving table 2 in a manner that the load receiving table 2 may rotate relative to the lifting mechanism B between a closing attitude at which the load receiving table 2 closes an opening 3 formed at a rear end part of a loading platform 1 and an open attitude at which the load receiving table 2 opens the opening 3; and biasing means which biases the load receiving table 2 in a direction such that the load receiving table 2 is closed. The biasing means biases the load receiving table 2 in the direction such that the load receiving table 2 is closed at the closing attitude of the loading receiving table 2 and exerts a biasing force, which is smaller than or equivalent to a self-weight moment of the load receiving table 2, in a direction such that the load receiving table 2 is closed at the opening attitude of the load receiving table 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a loading platform lifting device mounted on a loading vehicle. [Background technology]

[0002] In Patent Document 1, the loading platform is configured to be able to be raised and lowered by a lifting device, and is equipped with a torsion bar as a biasing means for biasing the loading platform in the closing direction so that the loading platform, which has been positioned in the highest position by the lifting device, can be easily rotated by an operator from an open position (approximately horizontal position) that opens an opening formed at the rear end of the loading platform to a closed position (approximately upright position) that closes the opening. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4212218 Publication Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, when the loading platform is in the closed position, the loading platform's own weight moment generated by its own weight and the biasing force (restoring force) of the torsion bar are the same, so the loading platform is in a neutral state with no biasing force applied, which means that there is a risk that the loading platform will flap due to the swaying of the vehicle while it is traveling, leaving room for improvement.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a loading platform lifting device capable of preventing the loading platform from flapping due to shaking while the vehicle is traveling. [Means for solving the problem]

[0006] The loading platform lifting device of the present invention comprises a loading platform on which luggage is placed, a lifting mechanism for raising and lowering the loading platform, a loading platform support section for rotatably supporting the loading platform relative to the lifting mechanism between a closed position in which the loading platform is raised so that luggage cannot be placed on it and an open position in which the loading platform is unfolded so that luggage can be placed on it, and a biasing means for biasing the loading platform in the direction of closing, wherein the biasing means biases the loading platform in the closing direction when the loading platform is in the closed position, and applies a biasing force less than the weight moment generated by the loading platform's own weight in the direction of closing the loading platform when the loading platform is in the open position.

[0007] According to the present invention, the biasing means biases the loading platform in the closing direction when the loading platform is in the closed position, thereby preventing the loading platform from flapping due to shaking during travel. In addition, even if the biasing means applies a biasing force equal to or less than the moment of the loading platform's own weight generated by its own weight when the loading platform is in the open position, the loading platform will not rotate in the closing direction, making it easy to load luggage onto the loading platform.

[0008] In the loading platform lifting device of the present invention, the biasing means may apply a biasing force to the loading platform that is equal to the moment of the loading platform's own weight when the loading platform is in an open position.

[0009] As described above, the biasing force of the biasing means can be maximized without exceeding the moment of the load receiving platform's own weight, and the load receiving platform can be raised from the closed position to the open position, thereby reducing the closing force required by the operator during closing (especially around 45 degrees, which is the intermediate part, when the opening and closing angle range is 90 degrees). Effect of the Invention

[0010] The present invention provides a loading platform lifting device that can prevent the loading platform from flapping due to shaking while the vehicle is traveling, by providing a biasing means that biases the loading platform in the closing direction when the loading platform is in the closed position. [Brief description of the drawings]

[0011] [Figure 1] 1 is a side view of a rear portion of a loading vehicle equipped with a loading platform lifting device of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. 4 is a longitudinal sectional rear view showing the arrangement of the torsion bar inside the load receiving platform. [Figure 4] FIG. 4 is a cross-sectional plan view showing the arrangement of torsion bars inside the load receiving platform. [Diagram 5] 4 is a cross-sectional view taken along line VV in FIG. [Figure 6] 6 is a cross-sectional view taken along the line VI-VI in FIG. [Figure 7] FIG. 1A is a diagram showing the configuration with the left adjustment plate attached to the left bracket as viewed from the vehicle width direction, and FIG. 1B is a vertical cross-sectional view showing the configuration with the left adjustment plate attached to the left bracket as viewed from the rear. [Figure 8] FIG. 1A is a diagram showing the configuration with the left adjustment plate attached to the left bracket as viewed from the vehicle width direction, and FIG. 1B is a vertical cross-sectional view showing the configuration with the left adjustment plate attached to the left bracket as viewed from the rear. [Figure 9] FIG. [Figure 10] This is a graph with the angle of the loading platform on the horizontal axis and the force on the vertical axis. [Figure 11] This is a graph showing the angle of the load carrier on the horizontal axis and the force on the vertical axis, using a torsion bar of a different configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The loading platform lifting device A of the present invention provided on a loading vehicle will be described below with reference to the drawings. As shown in Figs. 1 and 2, the loading platform lifting device A is provided at the rear end of the loading platform 1 of the loading vehicle, and includes a loading platform 2 on which a load is placed, a lifting mechanism B for lifting the loading platform 2, a loading platform support part C for supporting the loading platform 2 rotatably between a closed position (almost standing position) in which the loading platform 2 is raised so that a load cannot be placed on it relative to the lifting mechanism B and an open position (almost horizontal position) in which the loading platform 2 is unfolded so that a load can be placed on it, and a biasing means D (see Fig. 3) for biasing the loading platform 2 in a closing direction. The loading platform 2 is opened and closed by the manual force of an operator. In other words, the closed position is a position for closing the opening 3 formed at the rear end of the loading platform 1 shown in Fig. 2 from the rear, and the open position is a position for opening the opening 3.

[0013] The cargo receiving platform 2 includes a front plate 4 and a substantially rectangular back plate 5 spaced below the front plate 4. When the cargo receiving platform 2 is in the open position, the front plate 4 includes a loading surface 4A formed as a flat surface located at the top on which cargo is loaded, and an inclined surface 4B located rearwardly downward from the rear end of the loading surface 4A. A locking device for fixing the cargo receiving platform 2 in the closed position is provided between the left and right side surfaces of the cargo receiving platform 2 and a pair of left and right outer columns 12, 12 described below. The locking device includes a locking bar 32 provided slidably in the vehicle width direction so as to be able to enter and exit from each of the left and right side surfaces of the cargo receiving platform 2, and a hook 33 fixed to each of the left and right side surfaces of the pair of left and right outer columns 12, 12 and capable of engaging and disengaging with the locking bar 32. Therefore, by operating an operating part (not shown) provided on the back plate 5 of the receiving platform 2, the lock bars 32, 32 are protruded outward in the left-right direction from the receiving platform 2 and engaged with the hooks 33, 33, thereby fixing the receiving platform 2 in the closed position.

[0014] As shown in Fig. 3 and Fig. 4, the loading platform 2 has U-shaped storage plate parts 9, 10 fixed to two locations on both ends in the vehicle width direction of the reinforcing plate 6 fixed to the vehicle width direction center of the inner surface of the back plate 5, which form a storage space for storing the other end of the U-shaped torsion bars 7, 8 described later. Since one end portion, which is the outer end of the torsion bars 7, 8 described later, is located on the same axis, the torsion bars 7, 8 are inclined forward or backward in the vehicle width direction so that the other end portion, which is the inner end of the torsion bars 7, 8, does not interfere with each other. For this reason, as shown in Fig. 6, one (right) storage plate part 10 is configured to protrude greatly forward so as to be able to store the other end portion of the U-shaped torsion bar 7 on the left side, which is inclined forward, and the storage space is divided in the front-rear direction by two partition plates 11, 11 so that the other end portion of the U-shaped stored in the storage space does not rotate. In addition, the other (left) storage plate portion 9 is configured to be sized so that the other end of the U-shaped right torsion bar 8 does not rotate because the right torsion bar 8 is inclined rearward as shown in FIG.

[0015] As shown in FIG. 2, the lifting mechanism B includes a pair of left and right outer columns 12, 12, a pair of left and right inner columns 13, 13 that are inserted into the pair of left and right outer columns 12, 12 so that they can be raised and lowered, a cross member 14 whose both ends are welded between the pair of left and right outer columns 12, 12, and sliders 15, 15.

[0016] As shown in Figs. 1 and 2, the pair of left and right outer columns 12, 12 have the same configuration, and each outer column 12 is composed of a hollow rectangular cylinder, with a front wall portion 12A welded to the rear end of the loading platform 1, and a vertical slit 12S for guiding a slider 15 extending in the vertical direction to ascend and descend in the center of the vehicle width direction of the rear wall portion 12B. Also, a plate member 16 for dividing the internal space in the front-rear direction is provided in the center of the interior of each outer column 12 in the front-rear direction. The inner column 13 ascends and descends in the space behind this plate member 16. A guide roller 17 for guiding the ascending and descending of the inner column 13 is rotatably supported at the lower end of each outer column 12. Also, a guide roller 31 is rotatably supported at the upper end of each inner column 13 via a bracket 30, and the guide roller 31 rolls on the inner surface of the rear wall portion 12B of the outer column 12 when the inner column 13 ascends and descends to guide the ascending and descending of the inner column 13. Additionally, an upper fixed sheave 19 and a lower fixed sheave 19 for guiding a wire 18 (described later) are rotatably supported at the upper and lower ends of each outer column 12. Additionally, a stopper 20 is fixed to the lower end of each outer column 12, against which the lower end of an elastic stopper 29 provided on the inner column 13 abuts.

[0017] The pair of left and right inner columns 13, 13 have the same configuration, and each inner column 13 is composed of a hollow square cylinder. A plate-shaped slider 15 is inserted into each inner column 13 so as to be able to move up and down, and the rear end of the slider 15 is guided by a vertical slit 13S formed in the inner column 13 and a vertical slit 12S formed in the outer column 12 so as to be able to move up and down relative to the inner column 13 and the outer column 12. Guide rollers 21 are rotatably supported on the upper and lower parts of the slider 15, and when the slider 15 moves up and down relative to the inner column 13, these pair of upper and lower guide rollers 21, 21 roll on the inner surface of the inner column 13 to allow smooth movement up and down. A stopper rubber 22 is attached to the upper end of each slider 15, and this stopper rubber 22 engages with a base plate (not shown) provided at the upper end of the outer column 12 to regulate the upward movement position of the slider 15 relative to the outer column 12. A bracket 23 protruding rearward is fixed to the lower end of each slider 15, and the load receiving platform 2 is configured to be rotatable about a horizontal axis via a pin 24 to this bracket 23. A stay 25 is fixed to the lower end of each slider 15, and a stopper bolt 26 is attached to this stay 25. The stopper bolt 26 abuts against the upper surface of the base end of the rotating side of the load receiving platform 2 when the load receiving platform 2 rotates to the open position, thereby adjusting the open position of the load receiving platform 2. The pin 24 and bracket 23 form the load receiving platform support part C.

[0018] As shown in Figures 3, 4, 7(a), (b), and 8(a), (b), each bracket 23 is U-shaped in plan view and includes a pair of plate portions 23A, 23B parallel to each other in the left-right width direction, and a connecting plate portion 23C connecting the rear ends of the plate portions 23A, 23B. A circular through hole 23K is formed at the lower end of each of the pair of plate portions 23A, 23B, and the pin 24 is supported by the pair of plate portions 23A, 23B by passing through the through holes 23K, 23K. The pin 24 is formed in a substantially cylindrical shape and has a length that protrudes outward and inward from both ends of the plate portions 23A, 23B, and a square hole 24A into which one end of a torsion bar 7 described later fits is formed in the inner portion that protrudes inward. Further, a vertically long adjustment plate 27 for adjusting the torsional force of the torsion bar 7 (described later) is fixed in a penetrating state to the outer portion protruding outward so as to rotate integrally with the outer portion.

[0019] The adjustment plate 27 is formed with a through hole 27K through which the pin 24 passes at one end (lower end) in the longitudinal direction, and a plurality of (three in this case) bolt insertion through holes 27a, 27b, 27c are formed at a predetermined interval along the longitudinal direction on the other end side of the through hole 27K. The bolt insertion through holes 27a, 27b, 27c are formed so that their centers are positioned on a straight line passing through the center of the through hole 27K. In addition, the plate portion 23A located on the outer side of the bracket 23 is formed with three screw holes n1, n2, n3 into which the tip end of the bolt 28 passing through any one of the bolt insertion through holes 27a, 27b, 27c is screwed. Each of the screw holes n1, n2, n3 is misaligned in the radial direction of the through hole 27K when viewed from the center of the through hole 27K. 7(a), (b) and 9 show three screw holes n1, n2, and n3 formed in the plate portion 23A located outside the left bracket 23, and the lower the screw hole, the further downstream in the counterclockwise direction it is located. In other words, the screw hole is set so that the counterclockwise inclination angle of the vertical posture adjustment plate 27 increases as the screw hole is located lower. Specifically, the inclination angles are 5 degrees, 10 degrees, and 15 degrees. FIG. 8(a) and (b) show the right adjustment plate 27, and show a case where a bolt 28 is screwed into the lowest screw hole of the three screw holes formed in the plate portion 23A located outside the bracket 23, and the vertical posture adjustment plate 27 is inclined at an angle of 20 degrees clockwise. When the bolt 28 is screwed into the screw hole n2 in the center in the vertical direction, the vertical posture adjustment plate 27 is inclined at an angle of 15 degrees clockwise. When the bolt 28 is screwed into the screw hole n1 located at the top in the vertical direction, the adjustment plate 27 in the vertical position is tilted 10 degrees clockwise. In other words, the clockwise tilt angle becomes smaller as the bolt 28 is screwed into the upper screw hole. Also, the right adjustment plate 27 can be adjusted to a larger tilt angle than the left adjustment plate 27.

[0020] A general-purpose cross member 14 is used. This cross member 14 is made of a hollow rectangular cylinder, and inside the cross member 14, a hydraulic cylinder (not shown) is provided as a drive device for raising and lowering the cross member 14, and left and right movable sheaves (not shown) are provided side by side and can rotate freely in the vehicle width direction by the extension and contraction of the hydraulic cylinder.

[0021] Wires are wound around the left and right movable sheaves, and these wires 18, 18 are split into left and right and wound around upper fixed sheaves 19, 19, respectively, as shown in Fig. 1, and the ends of the wound wires 18, 18 are connected to the sliders 15, 15. Therefore, by extending the hydraulic cylinder, the sliders 15, 15 are raised via the wires 18, 18, and the load receiving platform 2 can be raised. Also, by contracting the hydraulic cylinder, the sliders 15, 15 are lowered via the wires 18, 18, and the load receiving platform 2 can be lowered.

[0022] The biasing means D is composed of two torsion bars 7, 8 having the same shape but different lengths, and each of the torsion bars 7 or 8 is made of a rod-like member, as shown in Figures 3 and 4, with one end formed in a square shape to fit into the square hole 24A of the pin 24, the other portion except for the one end formed in a round shape, and the other end formed in a U-shape. In this embodiment, the right torsion bar 8 is made longer than the left torsion bar 7 to reduce the spring constant and to make the right torsion bar 8 have a larger torsion than the left torsion bar 7.

[0023] One angular end of one (left) torsion bar 7 is fitted into a rectangular hole 24A of the pin 24, and a fastener such as a set screw or bolt is screwed into the pin 24 from the radial direction to prevent the torsion bar 7 from coming out of the pin 24. The other U-shaped end of one (left) torsion bar 7 is stored in the space formed by the right-side storage plate 10. And, as described above, the adjustment plate 27 that adjusts the torsional force of one (left) torsion bar 7 is fixed to the bracket 23 by a bolt 28 in a state rotated 5 degrees counterclockwise (see FIG. 7(a)).

[0024] One end of the square shape of the other (right) torsion bar 8 is fitted into the square hole 24A of the pin 24, and a fastener such as a set screw or bolt is screwed into the pin 24 from the radial direction to prevent the bar from coming off the pin 24. The other U-shaped end of the other (right) torsion bar 8 is stored in the space formed by the left storage plate 9. And, as described above, the adjustment plate 27 for adjusting the torsional force of the other (right) torsion bar 8 is fixed to the bracket 23 by the bolt 28 in a state rotated 20 degrees clockwise (see FIG. 8(a)). The axis of the straight part of the torsion bars 7, 8 is approximately aligned with the rotation center of the load receiving platform 2.

[0025] In Fig. 10, the horizontal axis represents the angle (posture) of the load receiving platform 2, and the horizontal axis represents the force corresponding to the angle (posture) of the load receiving platform 2. 0 degrees is the closed posture (upright posture) of the load receiving platform 2, and 90 degrees is the open posture (horizontal posture) of the load receiving platform 2. The biasing force (rotational biasing force, torque) of the torsion bars 7, 8 when a torsional force is applied to the torsion bars 7, 8 by the left and right adjustment plates 27, 27 as described above is shown by a straight line in the graph of Fig. 10. The dashed line in the graph of Fig. 10 indicates the biasing force of a conventional torsion bar, and the dashed line indicates the weight moment generated in the load receiving platform support part C due to the weight of the load receiving platform 2 itself. In order to increase the biasing force of the torsion bars 7, 8 acting on the load-receiving platform support part C in the closed position of the load-receiving platform 2 compared to the conventional method (Patent Document 1), and to make it coincide with the weight moment generated by the weight of the load-receiving platform 2 in the open position of the load-receiving platform 2, as described above, the length of the other torsion bar 8 is increased (thereby reducing the spring constant and making the slope of the graph shown by the solid line in FIG. 10 gentler) and the twist angle of the other torsion bar 8 in the closed position is increased (the biasing force of the torsion bar 8 is increased and the graph rises in parallel). The biasing force is adjusted so that only the other (right) torsion bar 8 applies biasing force when the load-receiving platform 2 is raised. Therefore, when the biasing force weakens due to aging, the torsion force of one (left) torsion bar 7 can be increased. In other words, the left and right have different purposes.

[0026] The biasing force of the torsion bars 7, 8 of the present invention shown by solid lines in Fig. 10 is not 0 even at 0 degrees, and a biasing force is being generated. Therefore, since the load receiving platform 2 is biased in the closing direction when the load receiving platform 2 is in the closed position (standing position), it is possible to prevent the load receiving platform 2 from flapping due to shaking during travel. Also, when the load receiving platform 2 is in the open position (horizontal position) at 90 degrees, the biasing force of the torsion bars 7, 8 of the present invention shown by solid lines in Fig. 10 acts on the load receiving platform 2 with a biasing force that is equal to the self-weight moment generated in the load receiving platform support part C due to the load receiving platform 2's own weight, so that the load receiving platform 2 does not rotate in the closing direction, and it is easy to load the load onto the load receiving platform 2. Also, the biasing force of the torsion bars 7, 8 can be raised between the closed position and the open position of the load receiving platform 2. In other words, since the straight line can be made closer to the dashed line in FIG. 10, the closing force required by the operator during closing (particularly near the 45 degree angle which is the intermediate portion) can be reduced.

[0027] The present invention can be modified in various ways without departing from the spirit of the invention. The specific configuration of each part is not limited to the above embodiment. For example, the length of the torsion bar 8 (which may be a compression spring) may be further increased to reduce the spring constant (the slope of the graph in FIG. 11 may be gentler than that in FIG. 10) and the biasing force of the torsion bar (which may be a compression spring) in the open position may be made smaller than the self-weight moment generated by the self-weight of the load-receiving platform 2. In other words, the biasing force P2 of the torsion bar shown at the right end of the solid line may be set so that the biasing force P2 is smaller than the self-weight moment P1.

[0028] In the above embodiment, a loading platform lifting device is shown in which the loading platform 2 is vertically raised and lowered along the outer columns 12, 12, but a loading platform lifting device equipped with an arm-type lifting mechanism using a parallel link mechanism may also be used. In this case, the loading platform support part that rotatably supports the loading platform is composed of a pin that connects the arm and the loading platform, and a bracket with a hole through which the pin passes.

[0029] In addition, in the above embodiment, a plurality of torsion bars 7, 8 are used as the biasing means, but a single torsion bar may be used, or a single or multiple compression springs (torsion coil springs) or leaf springs may be used.

[0030] In the above embodiment, the closed position of the load receiving platform 2 is set to 0 degrees, and the open position is set to 90 degrees, but the angles are not limited to these.

[0031] In the above embodiment, the axis of the straight portion of the torsion bars 7, 8 is aligned with the rotation center of the load receiving platform 2, but it does not necessarily have to be aligned with the axis. [Explanation of symbols]

[0032] Reference Signs List 1...cargo bed, 2...load receiving platform, 3...opening, 4...front plate, 4A...loading surface, 4B...inclined surface, 5...back plate, 6...reinforcing plate, 7, 8...torsion bar, 9, 10...accommodating plate portion, 11...partition plate, 12...outer column, 12A...front wall portion, 12B...rear wall portion, 12S...vertical slit, 13...inner column, 13...inner column, 13S...vertical slit, 14...cross member, 15...slider, 16...plate member, 17...guide roller, 18...wire, 19...fixed sheave, 20...stopper, 21...guide roller , 22... stopper rubber, 23... bracket, 23A, 23B... plate portion, 23C... connecting plate portion, 23K... through hole, 24... pin, 24A... hole, 25... stay, 26... stopper bolt, 27... adjustment plate, 27K... through hole, 27a, 27b, 27c... through hole for bolt insertion, 28... bolt, 29... elastic stopper, 30... bracket, 31... guide roller, 32... lock bar, 33... hook, A... load receiving platform lifting device, B... lifting mechanism, C... load receiving platform support portion, D... biasing means, n1, n2, n3... holes

Claims

1. the loading platform is provided on the loading platform and includes a loading platform on which luggage is placed, a lifting mechanism for raising and lowering the loading platform, a loading platform support section for supporting the loading platform rotatably relative to the lifting mechanism between a closed position in which the loading platform is raised so that luggage cannot be placed thereon and an open position in which the loading platform is unfolded so that luggage can be placed thereon, and a biasing means for biasing the loading platform in a direction in which it is closed; The biasing means biases the loading platform in a closing direction by making the biasing force of the biasing means greater than a moment of weight generated by the weight of the loading platform when the loading platform is in a closed position, and biases the loading platform in a closing direction by making a biasing force equal to or smaller than the moment of weight when the loading platform is in an open position, The load-receiving platform lifting device is characterized in that the biasing means is composed of two torsion bars of different lengths, the longer torsion bar having a smaller spring constant than the shorter torsion bar, and the shorter torsion bar having a larger torsion than the longer torsion bar.

2. 2. The loading platform lifting device according to claim 1, wherein the biasing means applies a biasing force to the loading platform that is equal to a moment of the loading platform's own weight when the loading platform is in an open position.

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