JP2003112560A - Arm structure of loading deck elevating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arm structure of a loading deck elevating device in which at least either one of storage or extension work is easy. SOLUTION: In the arm structure where tip end arms (13, 16) are rotated against base arms (4, 8) and a deck 18 is supported by this tip end arms, torsion springs 42 and 44 are provided for energizing the tip end arms in the reverse direction with a force smaller than the force given by gravity in the rotation direction at its rotation end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loading platform elevating device which is mounted on a rear portion or a side portion of a freight vehicle and is used for loading and unloading luggage.

[0002]

2. Description of the Related Art In a conventional load receiving platform raising / lowering device of a type in which a load receiving platform is moved up and down by rotating an arm, and a part of the arm is folded to store the load receiving platform under the floor of the vehicle body. It is necessary for the operator to lift the load receiving tray to store or deploy it. However, since the load receiving platform is a structure having sufficient mechanical strength to safely load the load, the load receiving platform is correspondingly heavy, and the weight of a part of the arm is not enough for the operator to store and deploy the load receiving platform. It will be a burden. Therefore, the lifting work of the loading tray was a heavy labor at the time of storage. In addition, the withdrawal work was a heavy labor even at the time of deployment.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide an arm structure of a load receiving / descending / descending device which facilitates at least one of storage and unfolding work.

[0004]

The arm structure of the load-carrying platform lifting device of the present invention is provided as a pair of left and right bodies on the vehicle body as the arm structure of the load-carrying platform lifting device for lifting, retracting, and unfolding the load carrier. It is connected between a pair of base arms that are rotatable in a predetermined range around a pair of upper and lower fulcrums A and B provided on the vehicle body, and action points C and D on the respective rotation end sides of these base arms. A base link mechanism that forms a quadrangle having four vertices of A, B, C, and D by a base connection member, and is provided so as to be rotatable around the action points C and D, respectively, and is provided with a folding position and a deployed position. C, D, E and F by a pair of distal end arms whose rotation ends are and a distal end connecting member connected between the action points E and F on the respective rotational end sides of these distal end arms. Flat with 4 vertices The tip end link mechanism that forms a line quadrangle and supports the load receiving platform on the side of the point of action E or F and the tip end arm are provided in the direction of rotation by gravity at the rotation end of at least one of them. And a biasing means for biasing in the opposite direction with a force smaller than the applied force (claim 1). In the arm structure of the load receiving platform elevating device configured as described above, the biasing means applies a force in the reverse direction with a force smaller than the force applied in the rotation direction by gravity at the rotation end of the tip arm. Momentum takes place. Therefore, although the distal end arm does not rotate in the opposite direction against the gravity, a certain effect of reducing the force applied by the gravity in the rotation direction can be obtained.

In the above-mentioned arm structure (claim 1), the urging means may be stored or released in accordance with the rotation of the tip arm, and its urging force may be maximized at the end of the rotation. (Claim 2). In this case, a sufficient biasing force is exerted at the time of starting the storage or unfolding of the load receiving tray, which is the most burdensome in operation, and this becomes the assisting force for operation.

In the arm structure (Claim 2), the urging means is a spring provided on the pin shaft of at least one of the C, D, E and F, and among the quadrangular sides of each link mechanism. Alternatively, the parallelogram may be deformed and biased by biasing one of the two sides intersecting at the one point in the direction of rotating the other side (claim 3). In this case, the spring can be arranged at an arbitrary pin position of the link mechanism as needed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a loading platform raising / lowering device employing an arm structure according to an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are a rear view and a side view, respectively, showing a loading platform elevating / lowering device 1 mounted below a luggage box 102 in a rear portion of a vehicle body 101 of a lorry.
In FIG. 2, the chassis 104 behind the rear wheel 103
Brackets 2A are attached to each of both side surfaces of
The support member 2B is attached to this. The loading platform elevating / lowering device 1 is attached to the support member 2B. The load receiving platform elevating / lowering device 1 shown in FIG. 2 is in a traveling state stored in a lower portion of the vehicle body 101. And, in use, as shown in FIG.
From the state shown in FIG. 3, FIG. 4, and FIG.
01 is pulled out and deployed.

Next, the structure of each part of the load receiving platform elevating device 1 will be described with reference to FIG. The loading platform lifting device 1 basically has a two-stage arm structure including a base arm (base lower arm 4, base upper arm 8) and a tip arm (tip lower arm 13, tip upper arm 16). is doing. In FIG. 4, the base lower arm 4 is
The pin 5 provided at the left end can be rotated about a fulcrum in a predetermined range around the fulcrum.
Supported by. The right end of the base lower arm 4 is connected to the base connecting member 7 via a pin 6 as an action point. On the other hand, the base upper arm 8 is rotatable about a pin 9 provided at the left end as a fulcrum within a predetermined range, and the pin 9 is supported by the support member 2B. The right end of the base upper arm 8 is connected to the base connecting member 7 via a pin 10 as an action point. Here, the pins 9 and 5 are a pair of upper and lower fulcrums A and B, and the pins 10 and 6 are action points C and D corresponding to the fulcrums A and B, respectively.
Then, the base lower arm 4, the base connecting member 7, and the base upper arm 8 have A, B, C, and D as four apexes, and a side CD
Is longer than the side AB, and the side BD is longer than the side AC.

A hydraulic cylinder 30 (shown only in FIG. 4) as a drive unit is connected to the base upper arm 8 and when the base upper arm 8 is rotated by the supply of hydraulic pressure, the base lower arm 4 is also moved. Rotate according to. Base upper arm 8
The two steel materials of the same shape arranged in the vehicle width direction are fixed to each other by the channel material 11. The channel material 11 not only functions to reinforce the base upper arm 8 but also regulates rotation of the tip upper arm 16.
That is, in the retracted state of FIG.
The tip portion of 6 (on the pin 17 side) contacts the upper surface of the channel member 11 to prevent the tip upper arm 16 from rotating further in the counterclockwise direction.

Next, referring to FIG.
Is pivotally attached to the lower base arm 4 by a pin 6 and is attached so as to be rotatable in a predetermined range in the counterclockwise direction from the position shown in the drawing. The right end of the tip lower arm 13 is connected to the tip connecting member 15 via a pin 14 as an action point. The L-shaped tip upper arm 16 is pivotally attached to the base upper arm 8 by the pin 10 and is rotatable counterclockwise within a predetermined range. Conversely, the tip upper arm 16 is rotated clockwise from the position shown in the figure. Has been given a detent. The right end of the tip upper arm 16 is connected to the tip connecting member 15 via a pin 17 as an action point. Where pin 1
When 7 and 14 are acting points E and F, respectively, the tip lower arm 13, the tip connecting member 15 and the tip upper arm 16 are tips of parallelograms having C, D, E and F as four vertexes. Part of the link mechanism.

The base link mechanism (ABCD), the tip end link mechanism (CDEF), and the load receiving base 18 supported by the tip end link mechanism are indicated by the alternate long and two short dashes line in FIG. The position is the rising end. Further, the tip end link mechanism (CDEF) can be folded as shown in FIGS. 3 and 2 by rotating counterclockwise with respect to the base link mechanism (ABCD).

On the other hand, in FIG. 5, the load receiving table 18 also has a foldable structure and is composed of a main plate 19 and a sub plate 20. Sub plate 20
Is rotatable counterclockwise from the position shown in the figure with respect to the main plate 19 (see FIG. 4). The main plate 19 is attached rotatably in the counterclockwise direction from the position shown in the figure with the pin 17 as a support point. Further, the stopper 21 attached to the main plate 19 is in contact with the right end surface of the tip end connecting member 15. The guide plate 22 projecting from the left end of the main plate 19 serves to fill a gap between the floor surface of the cargo box 102 and the cargo cradle 18 when loading and unloading cargo. The guide roller 23 engages with and guides the load receiving table 18 when the load receiving table lifting device 1 is stored. The guide roller 23 is rotatably supported by a guide roller support member 24 fixed to the support member 2B.

Next, an elevating mechanism of the load receiving table 18 will be described. FIG. 6 is a side view showing, in principle, the load receiving table 18 and an arm structure including a base link mechanism and a tip link mechanism for raising and lowering it.
~ It is common with FIG. The base linkage is represented by the scalene quadrilateral ABCD, where A and B are fixed points, C and D.
Is a movable point. Further, the tip end link mechanism is represented by a parallelogram CDEF, and each vertex C, D, E, F is a movable point. When the base lower arm 4 and the base upper arm 8 are rotated within the range shown in the drawing, the tip end portion is connected to the rotation end side and is provided with a rotation stop in the clockwise direction with respect to the base upper arm 8. The upper arm 16 rotates integrally,
Following this, the lower arm 13 at the tip also rotates. Side CD
And the side EF are always parallel to each other, and the load receiving base 18 always maintains a constant posture with respect to the side EF. Therefore, the inclination of the side CD determines the inclination of the loading tray 18. On the contrary, as long as the inclination of the side CD is constant, the posture of the cargo receiving table 18 is constant and is always sideways. For example, the loading platform 18 in the state shown in FIG. 3 is different from the state shown in FIG. 5 in that the sub-plate 20 is folded, but the inclination of the side CD is unchanged. Therefore, the posture of the load receiving base 18 (the inclination of the main plate 19) is completely the same in the range shown in FIG. 3 and the state shown by the solid line in FIG.

Further, as shown in FIG. 6, the tip end link mechanism (CDEF) has a steeper inclination angle than the inclination angle of the base upper arm 8 at the ascending end of the base upper arm 8 and the side CD. On the other hand, it plays a role of further pushing up the side EF and the loading tray 18. Therefore, the load receiving base 18 can be pushed up to a predetermined height while suppressing the rotation range of the base link mechanism (ABCD). Further, at the rising end of the load receiving tray, it is possible to avoid interference between the base arm and the like and the load box 102. On the contrary, at the descending end of the base upper arm 8, the tip end link mechanism has an inclination angle that is less than the inclination angle of the base upper arm 8 and suppresses the lowering of the side EF and the loading platform 18 with respect to the side CD. Playing a role.

The length relationships of the sides AB, CD, AC and BD of the base link mechanism (ABCD) in this embodiment are configured such that AB <CD and AC <BD. The magnitude relationship between the two opposite sides affects the link operation. FIG. 7 is a diagram showing how, in addition to the actual arrangement shown in FIG. 6, the size relationship between the sides AB and CD in a generally unequal-sided square link mechanism affects the link operation. (A) shows the link operation when AC = BD and AB <CD, (b)
On the contrary, shows the link operation when AB> CD.

In (a), the sides AB and CD are both vertical in the state shown by the solid line, but the side CD is inclined to the left as shown by the chain double-dashed line as the pivot side of the link mechanism rises. To do. Further, the side CD inclines to the right as the rotation side of the link mechanism descends. On the other hand, in the state shown by the solid line in (b), both sides AB and CD are vertical, but the side CD inclines to the right as shown by the chain double-dashed line as the rotation side of the link mechanism rises. . In addition, by lowering the rotation side of the link mechanism, the side CD
Leans to the left. That is, in (a) and (b),
The inclination direction of the side CD due to the rotation of the link mechanism has an opposite relationship. Further, in (a), if AC> BD, the inclination angle of the side CD with respect to the vertical at the time of ascending and at the time of descending decreases. On the contrary, when AC <BD, the inclination angle of the side CD with respect to the vertical direction at the time of ascending and descending increases. Further, if AC> BD in (b),
The angle of inclination of the side CD with respect to the vertical during the ascent and descent increases. On the other hand, when AC <BD, the inclination angle of the side CD with respect to the vertical direction at the time of ascending and descending decreases.

From the above, on the basis of the magnitude relationship between AB and CD (including the case where they are equal), the magnitude relationship between AC and BD (including the case where they are equal) is further required if necessary.
By constructing a unequal-sided quadrangular link mechanism that takes into account
The slope of D can be adjusted to the desired degree. In the present embodiment, the relationship of AB <CD and AC <BD is adopted as described above.

Returning to FIG. 6, the base link mechanism (ABCD)
At the rising end of, the side CD and the side EF are inclined to the left, that is, to the storage side of the load receiving base 18 with respect to the vertical line. In this state, the cargo table 18 is supported substantially horizontally. Then, when the base link mechanism descends from this state, the side CD and the side EF gently tilt. The inclination angles of the side CD and the side EF at the descending end are smaller than those at the ascending end, and the load receiving base 18 is in a tilted state. However,
The sides CD and EF are still inclined toward the storage side with respect to the vertical line even at the descending end. In this way, the receiving tray 1
The tilting operation of 8 is not performed separately from the lifting operation,
It is performed integrally with the lifting operation. Therefore, a dedicated structure for the tilt operation is unnecessary, and the structure is simple. Further, this tilting operation is performed extremely smoothly and is not accompanied by impact. Therefore, it is possible to prevent the luggage from falling or falling. On the contrary, when moving from the descending end to the ascending end, similarly, the load receiving base 18 changes its posture from the tilted state to the horizontal position extremely smoothly.

Next, the arm structure will be described in more detail. FIG. 8 is an exploded perspective view of the arm structure (an example on the left side when viewed from the rear of the vehicle body). In the figure, the base upper arm 8 is made of two plates as described above, and the tip upper arm 16 made of one plate is connected between the ends of the two plates. On the other hand, the lower arm 13 at the tip is composed of two plates,
Between the ends of the two plates, the base lower arm 4 made of one plate
(However, pipe-shaped members are welded to both ends.)
Is connected with. Further, as described above, the base connecting member 7 connects the above-mentioned C and D, and the tip connecting member 15 connects between the E and F. That is, the upper arm (base upper arm 8 and tip upper arm 1
6) and the lower arm (the base lower arm 4 and the tip lower arm 13) both have a structure in which a two-plate arm and a one-plate arm are connected.

Next, the urging means for the distal end arms (13, 16) which are omitted in the above description and the drawings will be described. FIG. 9 shows a state in which the loading tray 18 is unfolded (FIG. 5).
3 is a side view showing the detailed structure around the distal end link mechanism in FIG. Further, FIG. 10 is a plan view of the portion.
Although FIG. 10 shows only the port side (the left side when viewed from the rear of the vehicle body), the starboard side has the same bilaterally symmetrical structure.

In FIGS. 9 and 10, the base upper arm 8 is shown.
A bracket 40 is welded to the front end side surface of the so as to project outward in the vehicle width direction. A pin receiving portion 40a that supports the pin 10 is provided on an end surface of the bracket 40 on the outer side in the vehicle width direction, and the pin 10 extending outward on the vehicle width direction is inserted through the pin receiving portion 40a. A rod pin 41 is attached to the end of the pin 10 to prevent the pin from coming off. As shown in FIG. 10, a torsion spring 42 is attached to the pin 10 in the axial direction of the pin, and one end 42 a of the torsion spring 42 is attached to the tip upper arm 1.
6, the other end 42b is locked to the bracket 40, respectively. However, the other end 42b does not abut the bracket 40 in the state where the upper end arm 16 is unfolded as shown, and the torsion spring 42 is in a free state. Then, the tip upper arm 16 rotates with respect to the base upper arm 8 and the other end 42b moves toward the bracket 4 while being folded.
0, and the torsion spring 42 is charged thereafter. Therefore, the torsion spring 42 is in the most stored state at the end of the rotation of the upper end arm 16 in the folding direction with respect to the upper base arm 8 (the state of FIG. 2). At this time, the stored torsion spring 4
The urging force of 2 acts as a force to rotate the distal end arm (13, 16) with respect to the base arm (4, 8) in the deployment direction (clockwise direction). To the base arm (4, 8) to the tip arm (1
3, 16) is smaller than the force for turning the folding direction (counterclockwise direction). Therefore, in the state of FIGS. 2 and 3, the load receiving table 18 is not actually pushed up in the developing direction against the gravity, but a certain damping effect is given to the turning force by the gravity.

On the other hand, referring to FIG.
A locking portion 43 is welded to the inner side surface near the tip of so as to slightly project inward in the vehicle width direction. The pin 14 is extended inward in the vehicle width direction, and a torsion spring 44 is mounted in the pin axial direction. Although the pin 14 is integrated with the tip end connecting member 15, the pin 14 is only inserted into the tip end lower arm 13 and they are not integrated. A spring receiving member 45 is externally fitted to the inner end portion of the pin 14, and a rod pin 46 for preventing slipping out is inserted. One end 44 a of the torsion spring 44 is locked to the locking portion 43, and the other end 44 b is locked to the spring receiving member 45. The spring force of the torsion spring 44 is applied between the tip end connecting member 15 and the tip end lower arm 13,
The angle .alpha. (Angle DFE) in FIG. Further, the torsion spring 44 is stored most in the state in which the lower end arm 13 is deployed as shown in the figure.

In this way, when a force is applied in the direction of expanding the angle α, the tip upper arm 16 and the tip lower arm 1
A force for rotating the device 3 in the counterclockwise direction in FIG. 9 is applied to the tip end link mechanism. That is, parallelogram C
A deformation bias is applied to DEF to push E and F upward. At this time, the stored biasing force of the torsion spring 44 acts as a force for rotating the distal end arm (13, 16) with respect to the base arm (4, 8) in the folding direction. Force is applied to the base arm (4, 8) to the tip arm (1
3, 16) is smaller than the force for rotating the same in the developing direction. Therefore, the load receiving table 18 does not actually float up against gravity, but a certain damping effect is given to the turning force by gravity. Further, when the lower tip arm 13 is rotated in the folding direction from the state shown in FIG. 9, the torsion spring 44 is released accordingly, and becomes free during the rotation. Therefore, at the rotation end of the lower tip arm 13 with respect to the lower base arm 4 in the folding direction,
The torsion spring 44 is in a free state.

[0024] The load receiving platform elevating device 1 constructed as described above.
A series of normal operations (from pulling out to elevating and retracting) in FIG. 2 will be described with reference to FIGS. First, after stopping the vehicle and pulling the parking brake, the hydraulic cylinder 30 (FIG. 4) is driven from the state shown in FIG. 2 to rotate the base upper arm 8 and the base lower arm 4 clockwise to the lower end. Let Along with this, the loading tray 18 is moved to the guide roller 23.
As they are pushed away, the lower tip arm 13 and the upper tip arm 16 open slightly in the clockwise direction about the pins 6 and 10, respectively, and reach the state shown in FIG.

Next, the operator manually pulls the folded load receiving tray 18 rearward. Here, the tip end link mechanism (CDEF) is given a certain damping effect by the torsion spring 42 (FIG. 10) against the turning force in the counterclockwise direction due to gravity. This reducing effect serves as an assisting force for the operation, and the biasing force of the torsion spring 42 is large at the start of the operation. Therefore, the burden on the operator is reduced, and the operator can easily pull out the load receiving table 18. As a result, the lower end arm 1
3 and the upper arm 16 at the tip end are pin 6 and pin 1, respectively.
Rotate clockwise around 0. During this rotation, the parallelogram CDEF formed by the pins 10, 6, 17, and 14 changes its shape, but the side CD and the side EF maintain the parallel relationship. Therefore, the cargo receiving table 18 descends while maintaining a constant posture, and reaches near the floor surface as shown in FIG. Further, this rotation causes the torsion spring 44 (FIG. 10) to be charged. Then, the operator manually raises and rotates the sub-plate 20 of the load receiving base 18 to unfold it as shown in FIG.

When unloading, the hydraulic cylinder 30 (FIG. 4) is driven to rotate the base upper arm 8 and the base lower arm 4 counterclockwise. According to this
The tip upper arm 16 and the tip lower arm 13 also rotate,
The cradle 18 rises. During this ascent, the side CD of the base link mechanism (ABCD) gradually tilts with respect to the side AB, so that the side EF of the tip end link mechanism (CDEF) also tilts, and the load receiving platform 18 tilts. It gradually leveles from the state. In this way, the receiving tray 18 and the packing box 10
The loading platform 18 rises up to the rising end shown by the chain double-dashed line in FIG. Here, the operator transfers the luggage from the luggage box 102 to the cargo receiving table 18. After the transfer, the hydraulic cylinder 30 (FIG. 4) is driven to rotate the base upper arm 8 and the base lower arm 4 in the clockwise direction. In accordance with this, the tip upper arm 16 and the tip lower arm 13 also rotate, and the load receiving table 18 descends. During this descent, the side CD of the base link mechanism gradually tilts with respect to the side AB, so that the side EF also tilts, and the loading platform 18 gradually shifts from the substantially horizontal state to the tilted state. Reach the end of descent. Therefore, the luggage is not impacted, and the luggage can be prevented from falling or falling. When loading luggage in the luggage box 102, the above operations are performed in the reverse order.

In the ascending operation of the load receiving tray 18, the above-mentioned angle α (FIG. 9) becomes larger as the load receiving tray 18 rises from the lower end, and the biasing force of the torsion spring 44 (FIG. 10) accordingly. Decrease. This brings about the following effects. That is, the distal end arm (13, 1) expanded by the torsion spring 44 is
When a force is applied to 6) to fold it in the folding direction, the tip arm (13, 16) in the ascending rotation is moved relative to the base arm (4, 8) as shown in FIG. There is a possibility that it may rotate in the clockwise direction to prevent the normal lifting operation. However, if the urging force decreases as the load receiving platform 18 rises as described above, such a situation does not occur.

Next, when the loading tray elevating / lowering device 1 is to be stored, the operator folds the sub-plate 20 from the state shown by the solid line in FIG. 5 to the state shown in FIG. Lift up. Here, the tip end link mechanism (CDEF) is given a certain damping effect by the torsion spring 44 (FIG. 10) against the turning force in the clockwise direction due to gravity. This reducing effect is an assisting force for the operation, and the biasing force of the torsion spring 44 is maximum at the time of starting the operation. Therefore, the burden on the operator is reduced, and the operator can easily receive the load receiving table 18
Can be lifted. As a result, the lower tip arm 13 and the upper tip arm 16 rotate counterclockwise about the pin 6 and the pin 10, respectively. Further, this rotation again causes the torsion spring 42 (FIG. 10).
Is stored. In this way, the load receiving platform elevating / lowering device 1 returns to the state shown in FIG. Then, the operator operates the hydraulic cylinder 30.
(FIG. 4) is driven to drive the base upper arm 8 and the base lower arm 4
Rotate counterclockwise. As a result, the receiving stand 1
8 is in the state shown in FIG. 2 and is stored in the lower part of the vehicle body 101.

The arrangement of the torsion springs 42 and 44 in the above embodiment is not limited to the above arrangement,
Various design changes are possible. For example, in FIG. 11 showing the schematic configuration of the tip end link mechanism (CDEF), in order to reduce the weight of the load receiving tray 18 when storing from the deployed state, as shown by the arrows, E and F in the parallelogram CDEF are shown.
The force may be applied so as to push the angle DCE wide, or the force may be applied so as to narrow the angle CDF or CEF in order to perform the deformation bias in the direction of pushing up. Further, the tip upper arm 16 may be biased in the folding direction with respect to the base upper arm 8, or the tip lower arm 13 may be biased in the folding direction with respect to the base lower arm 4. Also,
The torsion springs may be provided at a plurality of places among them.

Similarly, in FIG. 12, in order to lightly pull out the loading tray 18 which is unfolded from the retracted state, the tip lower arm 13 is biased in the unfolding direction with respect to the lower base arm 4 as indicated by the arrow. You may. In addition, in order to apply a deformation bias in the direction of pushing up E and F in the parallelogram CDEF, a force is applied to spread the angle DCE or DFE, or a force is applied to narrow the angle CDF or CEF. May be. Further, the torsion springs may be provided at a plurality of places among them.

In this way, the torsion spring can be arranged at any pin position of the link mechanism as required. Therefore, the degree of freedom in design is large. In addition, in the above-described embodiment, the assisting force is generated in both directions of expansion and storage with respect to the distal end link mechanism (CDEF), but the assisting force is not always required in both directions.
Even if only one of the assisting forces is used, the effect of facilitating the operation is still obtained. Further, although the torsion springs 42 and 44 are used in the above embodiment, other springs can be used instead of this.

In the above embodiment, the load receiving platform elevating / lowering device 1 has been described as being pulled out to the rear of the vehicle body 101, but the same can be applied to a configuration in which it is pulled out to the side. Further, the main plate 19 of the load receiving table 18 is rotatably attached with the pin 17 as a support point, but a pin provided separately from the pin 17 may be rotatably attached as a support point, or It is also possible to rotatably attach the pin 14 as a support point.

[0033]

The load receiving platform lifting device of the present invention configured as described above has the following effects. According to the arm structure of the load receiving / descending / descending device of claim 1, the biasing means biases the tip end arm in the opposite direction with a force smaller than the force applied in the turning direction by gravity at the turning end of the arm. Therefore, a certain effect of reducing the force applied in the rotation direction by gravity can be obtained. Therefore, the load receiving stand becomes light in weight, and the work of storing and / or deploying the load receiving stand becomes easy.

According to the arm structure of the load receiving / descending / descending device of the second aspect, a sufficient biasing force is exerted at the start of storage or unfolding of the load receiving base, which is the most burdensome in operation, and this serves as an assisting force for the operation. , Easy to operate.

According to the arm structure of the load receiving / descending / descending device of the third aspect, the spring can be arranged at an arbitrary pin position of the link mechanism as needed, so that the degree of freedom in design is large.

[Brief description of drawings]

FIG. 1 is a rear view showing a state where a load receiving platform elevating device including an arm structure according to an embodiment of the present invention is attached to a lower part of a load box at a rear portion of a vehicle body of a freight vehicle.

FIG. 2 is a side view of the load receiving platform elevating device, showing a state of being stored in a vehicle body.

FIG. 3 is a side view of the load receiving platform elevating device, showing a state in which it is being developed or stored.

FIG. 4 is a side view of the load receiving platform elevating device, showing a state in which the distal end link mechanism is expanded with respect to the base link mechanism and the load receiving platform is folded.

FIG. 5 is a side view of the load receiving platform elevating device, showing a state in which the tip end link mechanism and the load receiving platform are deployed and moved up and down.

FIG. 6 is a side view showing, in principle, a load carrier in the load carrier lifting device, and an arm structure including a base link mechanism and a tip link mechanism for lifting and lowering the load carrier.

FIG. 7 is a side A in an unequal-sided square link mechanism.
It is a figure which shows how the magnitude relationship of B and CD influences a link operation.

FIG. 8 is an exploded perspective view of the arm structure shown in FIGS. 2 to 6 (an example on the left side when viewed from the rear of the vehicle body).

FIG. 9 is a side view showing a detailed structure around the distal end link mechanism in a state where the load receiving tray is unfolded (FIG. 4).

10 is a plan view of a portion shown in FIG.

FIG. 11 is a view showing a schematic configuration of a tip end link mechanism in a state in which the tip end arm of the load receiving platform elevating device is deployed.

FIG. 12 is a diagram showing a schematic configuration of a tip end link mechanism in a folded state of the tip end arm of the load receiving platform elevating device.

[Explanation of symbols]

1 Lifting device 4 base lower arm 5 pin (B) 6-pin (D) 7 Base connection member 8 base upper arm 9-pin (A) 10 pin (C) 13 Tip lower arm 14 pin (F) 15 Tip connection member 16 Tip upper arm 17 pin (E) 18 receiving stand 42,44 torsion spring 101 car body ABCD base link mechanism CDEF tip link mechanism

Claims (3)

[Claims] 1. A pair of left and right bodies are provided on a vehicle body as an arm structure of a load carrier lifting device for lifting, retracting, and deploying the load carrier.
Each arm structure has a pair of base arms that are rotatable within a predetermined range around a pair of upper and lower fulcrums A and B provided on the vehicle body, and action points C and D on the respective rotation end sides of these base arms.
A base linking member that is connected between the base connecting member that forms a quadrangle having A, B, C, and D as four vertices, and is rotatably provided around the operating points C and D, respectively. C, by a pair of distal end arms whose rotational ends are the folded position and the deployed position, and a distal end connecting member connected between the action points E and F on the respective rotational end sides of these distal end arms. A front end link mechanism that forms a parallelogram having D, E, and F as four vertices and that supports the load receiving platform on the side of the action point E or F, and the front end arm at at least one rotation end thereof. An arm structure of the load-carrying platform lifting device, comprising: a biasing unit that biases in a reverse direction with a force smaller than a force applied in the direction of rotation by gravity. 2. The lifting and lowering of the load receiving platform according to claim 1, wherein said urging means stores or releases energy in accordance with the rotation of said tip arm, and its urging force is maximized at the end of said rotation. Device arm structure. 3. The biasing means is a spring provided on a pin shaft of at least one of C, D, E and F, and the one of the square sides of each link mechanism
The arm structure of the load receiving platform elevating device according to claim 2, wherein the parallelogram is deformed and biased by biasing one of two sides intersecting at a point in a direction of rotating the other side with respect to the other.