JPH0825717B2 - Elevator synchronization mechanism - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lifting device used for lifting a worker or equipment for working at a high place and loading and unloading unnecessary materials, and more particularly to a pair of middle booms. Is rotatably supported in an X shape, and each middle boom has a configuration in which an upper boom and a lower boom that extend and contract in the axial direction are inserted, and by synchronizing the expansion and contraction of the lower boom and the upper boom, respectively. The present invention relates to a synchronizing mechanism of a lifting device that can lift a lifting platform above a base.

[0002]

2. Description of the Related Art In the construction of highways and high-rise buildings,
Elevating devices for vertically raising and lowering an elevating table have been widely used for assembling, painting, and repairing work in high places. It was possible to smoothly carry out various kinds of work at high places by placing a worker and materials on the lifting table of this lifting device and lifting or lowering them.

First, an outline of a conventional lifting device will be described with reference to FIG. The middle-stage booms A and B, which are hollow inside, are connected by a shaft C at their centers so as to be relatively rotatable in an X-shape. Upper booms E and D and lower booms F and G are slidably inserted from both ends of the middle booms A and B, respectively, and a lifting platform I is connected to the upper ends of the upper booms D and E. A base H is connected to the lower ends of the lower booms F and G. A pair of hydraulic cylinders J and K are interposed between the base H and the shaft C so as to form an isosceles triangle.

In order to raise the lift I in this structure, first, the shaft C is raised by the two hydraulic cylinders J and K, and the upper booms D and E and the lower booms F and G are opened in the middle booms A and B. Pulled out by the end, the lift I is the base H
Move upwards. Here, the lift I is the base H
In order to rise vertically upward with respect to the upper boom D,
The movement amounts i of the E and lower booms F and G pulled out from the open ends of the middle booms A and B, respectively, must always be synchronized. In order to satisfy this condition, a tuning mechanism that regulates the upper booms D and E and the lower booms F and G so that the moving amounts thereof are equal to each other is provided.

Various tuning mechanisms have been conventionally used for this purpose. Among them, one that uses a sprocket wheel and a chain is a simple and reliable mechanism. The outline of the tuning mechanism by the sprocket wheel and the chain is as shown in FIG. That is, a pair of sprocket wheels a and b are rotatably supported so as to be coaxial with the axis C,
Sprocket wheels d and e having a slightly smaller diameter are pivotally supported at the lower ends of the middle booms A and B, respectively. And
A chain f is wound between the sprocket wheels a and d, and a chain g is wound between the sprocket wheels b and e. With such a structure, when the sprocket wheels d and e rotate, the pinion connected to the sprocket wheels d and e is rotated, so that the rack fixed to the lower booms F and G is pulled out. When such a tuning mechanism is housed in the telescopic boom of FIG. 1 and is operated to extend the hydraulic cylinders J and K, theoretically, as shown in FIG.
It will rise vertically upward with respect to. The aforementioned sprocket wheels a and b rotate coaxially, the sprocket wheels d and e rotate at the same rotation ratio, and the movement amount of the lower boom F that can be pulled out from the middle boom A and the middle boom B
This is because the movement amounts of the lower boom G that is pulled out from the lower end of are the same. According to such a theory, the lifting platform I rises along a locus perpendicular to the base H like a locus V in FIG.

However, in practice, the hydraulic cylinder J,
When K is extended to elevate the lifting platform I, the lifting platform I rises along a curve of a locus W which is slightly close to a parabola. Then, when the hydraulic cylinders J and K are maximally extended, the lifting platform I is stopped at a distance S from the base H in the horizontal direction. That is, the lifting platform I is deviated from the target working position by the distance S from the theoretical raised position. Now, the above-mentioned two hydraulic cylinders J and K
The same hydraulic pressure is supplied to each of them, and the axis C, which is a connecting point of the hydraulic cylinders J and K, is set so as to draw a locus such that the axis C always moves vertically upward from the base H. Therefore, if the lifting platform I is displaced in the horizontal direction by S when the hydraulic cylinders J and K are maximally extended, the force given to the shaft C by the hydraulic cylinders J and K is a horizontal component Y. However, an unbalanced load is applied to the shaft C. As described above, the error in the number of revolutions caused by the revolution of the sprocket wheels a and b is caused by the deviation S of the lift I.
As a result, this deviation S is applied as an eccentric load to the shaft C that is the center of the middle booms A and B.
Then, since the lifting platform I does not rise straight along the vertical line V, it becomes impossible to accurately control the raising position. However, the biggest problem is the sprocket wheels a, b, d, e.
And the load applied to the chains f and g. The sprocket wheels a, b, d, e and the chains f, g are originally designed to rotate in synchronization with each other, and the upper booms D, E and the lower booms F, G have the same withdrawal amount and the vertical lines. It is regulated so as to draw the trajectory of V. As described above, if the lifting platform I moves by the displacement S, the pull-out amounts of the upper booms D and E and the lower booms F and G differ, and as a result, the sprocket wheels a, b, d, e and the chain. An unreasonable load will be applied to f and g, and accidents such as tooth breakage of the sprocket wheels a, b, d and e and breakage of the chains f and g will occur depending on long-term use and the length of the deviation S. I decided to do it. The breakage of the chains f and g is extremely dangerous because it causes an accident of the lifting device to fall. In order to prevent such an accident from occurring, it has been desired to minimize the horizontal shift S when the lift I is in the maximum raised state.

[0007]

The cause of this phenomenon is that the sprocket wheels a and b rotate in synchronization with each other as shown in FIG. 3, and the chains f and g respectively cause small sprocket wheels d and e. Is to rotate. These sprocket wheels a,
The middle booms A and B rise as soon as b rotates,
The middle booms A and B themselves also rotate about the axis C, and the sprocket wheels a and b rotate about their own axes and the middle booms A and B rotate.
It will be affected by the revolution of B. For example, when the middle booms A and B are elevated above the horizontal position by an angle θ, the spcket wheel a and b are rotated by the angle θ in addition to the rotation by the rotation with respect to the horizontal position. Because. This angle θ is added to the spcket wheels a and b which are originally rotating in synchronization, and at the same time, the chains f and g are driven to rotate the sprocket wheels d and e. This is because there is a deviation in the rotation angle of.

The deviations of the rotations of these sprocket wheels d and e can be expressed as follows.

The number of teeth of the sprocket wheel a is Ta,

The number of teeth of the spcket wheel le b is Tb,

If the number of teeth of the sprocket wheel d is Td,

The number of teeth of the sprocket wheel e is Te,

[0013] Then, the sprocket wheel d is moved from the state where the hydraulic cylinders J and K are contracted at the shortest to the time when the hydraulic cylinders are extended to the maximum (that is, when the shaft C is fully lifted as shown in FIG. 1). If the shift amount of the number of teeth of the chain f is x, then it becomes as follows (at this time, Td = Te).

X = θ (Ta + Tb) / 360

A deviation S of the horizontal movement of the lift I shown in FIG.
In order to eliminate the above (to reduce the amount of movement of S to 0), the deviation amount x of the number of teeth of the chain f may be set to zero. Here, assuming that the number of teeth of the spcket wheels a and b is (Ta ≧ Tb), the sprocket wheel d rotates during the period in which the hydraulic cylinders J and K contract from the shortest to the maximum expansion. If the number is r,

Te = Td (Tb / Ta) + (x / r)

It is expressed as follows. This means that if the two sprocket wheels d and e have different numbers of teeth, the hydraulic cylinders J and K are maximally extended and the shaft C is lifted as shown in FIG. Upper boom E,
The movement deviation of the lifting platform I when the D and the lower booms F and G are pulled out to the maximum is eliminated. From this,
In order to easily eliminate the deviation S, the number of teeth Te of the sprocket wheel e on the opposite side is set to be one more than the number of teeth Td of the sprocket wheel d.

[0018]

In view of the above-mentioned drawbacks, the present invention connects a pair of inner hollow middle booms rotatably in an X-shape at their respective centers, and has respective ends in each middle boom. The upper and lower booms that expand and contract at the bottom are slidably inserted, and each end of the lower boom is axially attached to the base with a gap, and each end of the upper boom is attached to the lift base with a gap. The upper and lower booms are slid in synchronization with each other by vertically moving the middle boom, and the upper and lower booms are slid in synchronization with each other. A pair of sprocket wheels are rotatably connected to the center of rotation of the boom, a sprocket wheel is connected to one end of each middle boom, and the sprocket wheel at the center of rotation and the middle boo The sprocket wheels at one end of the boom are linked by a chain, the rack is fixed in the length direction of the lower boom, and the pinion is meshed with the rack by pivotally supporting it at one end of the middle boom. It is driven by the sprocket wheel provided at one end of the lower boom, and the extension amount of the lower boom relative to the middle boom is synchronized with these sprocket wheel, chain, rack, and pinion.The number of teeth of the sprocket wheel provided at one end of one middle boom The number of teeth is smaller than the number of teeth of a sprocket wheel provided at one end of the other middle boom, and a synchronizing mechanism for a lifting device is provided.

[0019]

In the present invention, the moving amount of each lower boom extending from the pair of middle booms can be synchronized by the synchronizing mechanism composed of the chain and the sprocket wheel. For this synchronization, a sprocket wheel and a chain are used, but the number of teeth of the sprocket wheel fixed to one middle boom is different from the number of teeth of the sprocket wheel fixed to the other middle boom. is there. Due to the difference in the number of teeth of both sprocket wheels, there is a difference in rotation between the two, resulting in a difference in the movement amount of the lower boom, and this difference in movement amount is shown in FIG.
It is possible to correct the movement deviation S of the lifting platform I, which is indicated by, to position the lifting platform I vertically above the base H at the position where the hydraulic cylinders J and K are maximally extended. This correction prevents the sprocket wheel and the chain from being unduly loaded and prevents accidents such as tooth breakage and breakage.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention will be described below with reference to the drawings. FIG. 4 is a perspective view showing a state in which the lifting device mounted on the body of a truck is lifted to the maximum height, and FIG. 5 shows the lifting device in the lowest position. 7 is a side view showing a state in which the elevator is lowered to the maximum height position, and FIG.
[Fig. 4] is a rear view showing a state where the lifting platform is lifted to the maximum height position.

First, reference numeral 1 in the figure is a vehicle body of a truck, and front wheels 2 and rear wheels 3 are axially supported on the front, rear, left and right of the vehicle body 1, respectively. A cabin 4 is provided above the front wheel 2, and further outriggers 5 are fixed to the center of the vehicle body 1 and to the left and right of the rear end of the vehicle body 1 so as to project laterally. An elevating mechanism 6 is placed on the upper surface of the vehicle body 1,
An elevating table 7 is fixed to the upper part of the elevating mechanism 6, and a handrail 8 for preventing a drop is provided around the elevating table 7.

The elevating mechanism 6 is composed of four telescopic boom bodies, each telescopic boom body being a middle boom 10, 11, 12, 13 and a lower boom 15, 16, 1.
7, 18 and upper booms 19, 20, 21, 22. Therefore, the middle boom 10 and the lower boom 1
5. The upper boom 19 forms one telescopic boom body, the middle boom 11, the lower boom 16 and the upper boom 22 form one telescopic boom body, the middle boom 12, the lower boom 1
7, the upper boom 21 constitutes one telescopic boom body, and the middle boom 13, the lower boom 18 and the upper boom 22 constitute one telescopic boom body. The four telescopic booms are set as a set of two, and the middle boom 1
0 and the middle boom 11 are one combination, and the middle booms 12 and 13 are one combination. Therefore, the middle boom 10 and the middle boom 11 are rotatably connected to each other by a shaft at their centers so that they can relatively rotate, and the centers of the middle boom 12 and the middle boom 13 are also relatively rotatable by the shaft. Are linked to. In addition, two sets of opposing center, that is, the middle boom 11 and the middle boom 13 are provided.
The central portions of the two are rotatably connected by a lifting shaft 43. Then, the lower booms 15, 16, 17, 18
Connecting pieces 23, 24, 25, 26 are fixed to the respective lower ends of the vehicle body 1, fixing pieces 31, 33 are fixed to the left and right rear surfaces of the upper surface of the vehicle body 1, and fixed to left and right front surface upper surfaces of the vehicle body 1. Piece 3
2, 34 are fixed to the left and right. The fixing piece 31 is pin-connected to the connecting piece 23, the fixing piece 32 is pin-connecting to the connecting piece 24, the fixing piece 33 is pin-connecting to the connecting piece 25, and the fixing piece 34 is pin-connecting to the connecting piece 26. . Further, connecting pieces 27, 28, 29, 30 are fixed to the upper ends of the upper booms 19, 20, 21, 22 respectively, and fixing pieces 35, 37 are fixed to the left and right front lower surfaces of the lifting platform 7. Fixing pieces 36 and 38 are fixed to the left and right behind the lower surface of the lift 7. The connection piece 27 is pin-connected to the fixed piece 35, the connection piece 28 is pin-connected to the fixed piece 36, the connection piece 29 is pin-connected to the fixed piece 37, and the connection piece 30 is pin-connected to the fixed piece 38. . With such a configuration, the elevating mechanism 6 is configured to have an X shape when viewed from the side (see FIG. 6).

The front and rear of the upper surface of the vehicle body 1 are respectively connected to the bases of hydraulic cylinders 41 and 42 which extend and contract in a plurality of stages, and the tips of the cylinder rods extending from the hydraulic cylinders 41 and 42 are connected to a lifting shaft 43. There is.
Therefore, the two hydraulic cylinders 41 and 42 are set to have an inverted V-shape when viewed from the side in relation to the vehicle body 1. By synchronizing the hydraulic pressures supplied to the hydraulic cylinders 41 and 42, Hydraulic cylinders 41 and 42 are always reverse V
The lifting shaft 43, which extends so as to have a character shape, is controlled so as to rise vertically upward with respect to the vehicle body 1, which is a connection point between the ends of the two.

Further, a fixing piece 3 fixed to the upper surface of the vehicle body 1.
The distance between 1 and 32 and the distance between the fixing pieces 33 and 34 are set to be the same as the distance between the fixing pieces 35 and 36 and the distance between the fixing pieces 37 and 38 fixed to the lower surface of the lifting table 7. Since the lengths are equal, the lower booms 15 to 18 and the upper booms 19 to 22 are raised and pulled out at the same speed from the middle booms 10 to 13, so that the middle booms 10 to 13 and the lower boom 15 are seen from the side. ~ 18, upper boom 1
9 to 22, the vehicle body 1, and the lifting platform 7 are configured to form two isosceles triangles at the top and bottom and always form an X shape.

Next, FIG. 8, FIG. 9 and FIG. 10 show the internal construction of the above-mentioned four telescopic boom bodies. Specifically, the middle boom 1 is a representative example of the four telescopic boom bodies.
The internal structure of 0 is shown. However, other middle boom 1
The internal structures of 1, 12, and 13 have the same configuration, and there is no difference in the configuration.

The middle boom 10 is formed by bending a thin steel plate and has an internal hollow structure in the longitudinal direction having a square cross section. From one end (right side in FIG. 8) of the middle boom 10. The lower boom 15 is slidably inserted. The lower boom 15 has an internal hollow structure in which a thin-walled steel plate is bent to have an R-shaped cross section. Inside the lower boom 15, the other end of the middle boom 10 (on the left side in FIG. 8).
The upper boom 19 inserted from above is slidably inserted. Fan-shaped shaft support pieces 44 and 45 are fixed to both ends of the middle boom 10, respectively.
4 and 45 each have a pair of guide roller rollers 4
6, 47 are rotatably supported up and down. The upper and lower surfaces of the lower boom 15 are brought into contact with each other between the pair of rollers 46, 46, and the lower boom 15 is smoothly slid by the middle boom 10 by these rollers 46, 46. Further, the upper and lower surfaces of the upper boom 19 are in contact with each other between the pair of rollers 47, 47, and the upper boom 19 is held by the rollers 47, 47 so as to slide smoothly from the inside of the lower boom 15. There is. A rack 52 is fixed to the lower surface of the lower boom 15 along the lengthwise direction thereof, and the tooth surface of a pinion 53 pivotally supported by the shaft support piece 44 is meshed with the rack 52.

A gear box 48 is fixed to the lower portion of the middle boom 10 at a position close to the shaft support piece 45. Inside the gear box 48, two sprocket wheels 49, 50 are provided. It is pivoted. And
Both ends of a chain 51 are connected to the tip of the lower boom 15 (the deepest position in the middle boom 10) and the tip of the upper boom 19 (the deepest position in the middle boom 10). The sprocket wheel 4 on the way
It is wound around the outer circumference of 9, 50 so as to form an S shape. The chain 51 restricts the amount of movement of the lower boom 15 and the upper boom 19 that is pulled out from the middle boom 10, so that the lower boom 15 can be moved from both ends of the middle boom 10.
And the upper boom 19 are slid by the same amount of expansion and contraction.

Next, FIG. 9 shows a sectional structure taken along line XX in FIG. In FIG. 9, the shaft 5 is interposed between the shaft support pieces 44 fixed to both sides of the middle boom 10.
4 is rotatably supported, and a pinion 53 is fixed to the center of the shaft 54. The tooth surface of the pinion 53 is in mesh with the rack 52 fixed along the length direction of the lower boom 15. A sprocket wheel 55 is fixed to the side of the shaft 54 and outside the shaft support piece 44.

Further, FIG. 10 shows the vicinity of the center of the telescopic boom body which is a set of two ropes. Middle boom 10
A belt-shaped holder 59 is wound around and fixed to the outer periphery of the center of the, and a cylindrical collar 58 is fixed to the side surface of the holder 59 facing the middle boom 11.
Then, the middle boom 11 that constitutes the other telescopic boom body
A belt-shaped holding body 60 is also wound around and fixed to the outer periphery of the center of the middle boom 10.
The connecting shaft 1 has a stepped cylindrical shape on the side surface facing the
4 is stuck. The connecting shaft 14 is inserted into the collar 58, and the collar 58 and the connecting shaft 14 are combined so that the middle boom 10 and the middle boom 11 can rotate relative to each other. Further, a groove-shaped engaging groove 62 is formed on the outer periphery of the tip of the connecting shaft 14, and the engaging groove 6 is formed.
2 has an engaging piece 63 meshed with it.
Is secured to the collar 58 by screws 64. By engaging the engagement piece 63 with the engagement groove 62, the middle boom 10 is held rotatably without being separated from the middle boom 11. In addition, a cylindrical collar 65 is inserted through the center of the connecting shaft 14, and the collar 65 is rotatably supported by the connecting shaft 14. And two sprocket wheels 66 and 67 are fixed.

A cylindrical support is provided on the side surface of the holding body 60 fixed to the outer periphery of the middle boom 11, and the side surface facing the other middle boom 12 (the side opposite to the connecting shaft 14). The shaft 61 is fixed. The support shaft 61 is rotatably inserted into the space of the sliding hole formed in the lifting shaft 43,
The support shaft 61 and the lifting shaft 43 can rotate relative to each other. With such a configuration, the middle boom 10,
11 and another set of middle booms 12 and 13 is the connecting shaft 1
4. The hoisting shafts 43 are assembled in such a manner that the hoisting shafts 43 rotate in opposite directions, and the four telescopic boom bodies maintain a constant distance.

Next, FIG. 11 shows a synchronizing mechanism provided between the middle boom 10 and the middle boom 11 which are the above-mentioned pair of telescopic boom bodies, and the lower booms 15 and 16 can be operated by this synchronizing mechanism. The amount of extension sliding from the middle booms 10 and 11 is restricted.

As described above, the sprocket wheels 66 and 67 are fixed to the outer periphery of the collar 65, and the sprocket wheel 55 is fixed to one end of the shaft 54 pivotally supported on the lower end of the middle boom 10. A chain 76 is wound between the sprocket wheel 66 and the sprocket wheel 55. A pinion 53 is fixed to the center of the shaft 54.
3 is meshed with a rack 52 fixed along the length direction of the lower surface of the lower boom 15. A rack 70 is fixedly attached to the lower surface of the lower boom 16 inserted through the pair of middle booms 11 in the longitudinal direction, and a pinion 71 is engaged with the rack 70. And the lower boom 16
A shaft 72 is rotatably supported at the lower end of the shaft 72, a pinion 71 is fixed to the center of the shaft 72, and a gear 73 is fixed to the other end of the shaft 72.
A gear 74 meshes with the gear 73, and the gear 7
4, a sprocket wheel 75 is connected coaxially.
A chain 77 is wound between the sprocket wheel 75 and the sprocket wheel 67. The sprocket wheels 66 and 67 have the same number of teeth, but when the numbers of teeth of the sprocket wheel 55 and the sprocket wheel 75 are compared, the number of teeth of the sprocket wheel 75 is "1 tooth" than the number of teeth of the sprocket wheel 55. 』I just set a lot. The pinion 53 and the pinion 71 have the same number of teeth, and the gears 73 and 74 have the same diameter.

With this structure, when the collar 65 rotates, the sprocket wheels 66 and 67 rotate at the same rotation angle, the chains 76 and 77 rotate at the same moving speed, and the moving speed of the chains 76 and 77 changes. It is transmitted to the sprocket wheel 55 and the sprocket wheel 75.
When this sprocket wheel 55 rotates, the shaft 5
The pinion 53 is driven by the pinion 53 and the rack 52 is driven from the position 4. Therefore, the rack 52, that is, the lower boom 15 is pulled out from the middle boom 10.
When the sprocket wheel 75 is rotated, the gear 7
4 is driven, and at the same time, the gear 73 rotates in the opposite direction, the rotation of the gear 73 is transmitted to the pinion 71 via the shaft 72, and as a result, the rack 70, that is, the lower boom 16 is pulled out from the middle boom 11. . Due to this interlocking action, the lower boom 15 and the lower boom 16 are pulled out from the middle booms 10 and 11 at the same speed. At this time, since the number of teeth of the sprocket wheel 75 is “one more” than the number of teeth of the sprocket wheel 55, the length by which the lower boom 16 is pulled out from the middle boom 11 is the length by which the lower boom 15 is pulled out from the middle boom 10. Is controlled to be smaller than The difference in the pull-out amounts of the lower boom 15 and the lower boom 16 eliminates the deviation S shown in FIG.

FIG. 12 shows the lower boom 1 described above.
Only the structure of the synchronization mechanism for pulling out 5 and 16 from the middle booms 10 and 11 is shown.

Next, FIG. 13 concretely shows the interlocking structure of each part in the telescopic boom body which is a set of two. Inside the middle boom 10, the lower boom 15
The upper and lower ends of the upper boom 19 and the upper boom 19 are connected to each other by a chain 51, and the chain 51 is wound around the sprocket wheels 49 and 50 so as to draw an S-shape and reversed. Therefore, when the lower boom 15 is pulled out from the middle boom 10, the chain 51 pulls the upper boom 19 and, as a result, the lower boom 1
5 and the upper boom 19 have the same movement amount withdrawn from the middle boom 10. Inside the other middle boom 11, the upper boom and the lower boom of the lower boom 16 and the upper boom 20 are connected by a chain 80, and the chain 80 is wound by sprocket wheels 78, 79 so as to draw an S-shape. Has been reversed. Therefore, when the lower boom 16 is pulled out from the middle boom 11, the upper boom 20 is pulled by the chain 80, and as a result, the lower boom 16 and the upper boom 20 have the same movement amount pulled out from the middle boom 11. With such a configuration, the lower booms 15, 16 and the upper boom 1 that are pulled out from the middle booms 10, 11 by moving the chains 76, 77, 51, 80 respectively.
The movement amounts of 9 and 20 are all the same. Therefore, the two telescopic booms forming the X-shape radially extend the same moving distance i as shown in FIG. 1, and the lifting platform 7 rises vertically upward with respect to the vehicle body 1. Become.

In such a structure for synchronization, as described above, the sprocket wheels 66, 67, 5 are used.
Since the number of teeth of the sprocket wheel 75 is larger than the number of teeth of the sprocket wheel 55, the number of teeth of the sprocket wheel 75 is larger than the number of teeth of the sprocket wheel 55. 16 is greatly lifted, and the connecting shaft 14 moves up in an arc. At this initial stage, the locus of the connecting shaft 14 largely bulges outward (indicated by locus Z in FIG. 14) because the angular velocity of the rising of the middle booms 10 and 11 is high. However, when the two hydraulic cylinders 41, 42 are maximally extended, a difference in the number of teeth between the sprocket wheel 75 and the sprocket wheel 55 is set, so that the length of the lower boom 16 pulled out from the middle boom 11 and the lower boom 16 are There is a difference in the distance with which the middle boom 10 is pulled out. Therefore, the tip of the upper boom 20 that once drew a large parabola outward is pulled back toward the vertical line V and draws an arc as shown by the trajectory Z in FIG. Then, when the hydraulic cylinders 41, 42 are in the maximum extended state (state shown by the solid line in FIG. 14), the pin at the upper end of the upper boom 20 is set so as to coincide with the position of the vertical line V. As described above, the hydraulic cylinder 41,
Since the same amount of hydraulic pressure is supplied to 42 and the amounts of extension of both are set to be the same, when the hydraulic cylinders 41, 42 are maximally extended, the upper boom 2
The fact that the pin at the upper end of 0 coincides with the position of the vertical line V means that the lower booms 15, 16 and the upper booms 19, 20 are moved evenly from the middle booms 10, 11, and the chains 76, 77 Is not overloaded. Further, the horizontal unbalanced load generated from the hydraulic cylinders 41 and 42 does not occur on the connecting shaft 14,
The unbalanced load in the horizontal direction cannot be applied to the telescopic boom. In this way, the sprocket wheels 66, 67, 55, 75 and the chain 7 forming the synchronization mechanism
6, 77 and pinion 53, 71, rack 52, 70
Therefore, it is possible to prevent the chain 76, 77 from being broken and the sprocket wheels 66, 67, 55, 75 from being damaged such as missing teeth.

[0037]

Since the present invention is configured as described above, it is possible to achieve synchronization of the elevating device that expands and contracts in an X shape by a basically synchronizing mechanism using a chain and a sprocket. Also, in this synchronous movement, the fatal error that occurs from the mechanism that synchronizes the sprocket wheel by pivotally supporting it to the middle boom can be eliminated by setting the number of teeth of the sprocket wheel, and the lift table Horizontal displacement can be eliminated when raised to the maximum height. For this reason, it is possible to eliminate the generation of an unreasonable load that occurs due to the telescopic boom body acting with a pair of hydraulic cylinders, and to prevent the failure of gears, sprocket wheels, chains, etc., which compose the synchronization mechanism, to break. It can be resolved. Further, it is possible to prevent the deviation of the ascent by a very simple structure, and it is possible to prevent the accident of the lifting device from falling due to the cutting of the chain or the like.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a lifting device that extends in an X shape.

FIG. 2 is a lift I that is obtained by operating a conventional lifting device.
It is explanatory drawing which shows the deviation of.

FIG. 3 is an explanatory view showing a synchronizing mechanism in a conventional lifting device.

FIG. 4 is a perspective view showing an embodiment in which the lifting device of the present invention is mounted on a truck.

FIG. 5 is a side view showing a state in which the lifting table is lowered to the lowest position.

FIG. 6 is a side view showing a state in which the lifting table is lifted to a maximum height position.

FIG. 7 is a rear view showing a state in which the lifting platform is lifted to a maximum height position.

FIG. 8 is a side sectional view showing the internal structure of the telescopic boom body in the embodiment of the present invention.

FIG. 9 is a vertical cross-sectional view of the telescopic boom body taken along line XX in FIG.

FIG. 10 is a vertical cross-sectional view showing a connecting mechanism at the center of the above-described telescopic boom body.

FIG. 11 is a partially cutaway perspective view showing a structure of a synchronizing mechanism of the above telescopic boom body.

FIG. 12 is an explanatory view showing only the configuration of the synchronization mechanism of the telescopic boom body of the above.

FIG. 13 is a skeleton diagram showing a synchronizing mechanism for the entire telescopic boom body of the above.

FIG. 14 is an explanatory diagram showing a locus due to movement of the telescopic boom body according to the present embodiment. 1 Vehicle Body 6 Lifting Mechanism 7 Lifting Platform 10 Middle Boom 11 Middle Boom 12 Middle Boom 12 Middle Boom 13 Middle Boom 15 Lower Boom 16 Lower Boom 17 Lower Boom 18 Lower Boom 19 Upper Boom 20 Upper Boom 21 Upper Boom 22 Upper Boom 41 Hydraulic Cylinder 42 Hydraulic Cylinder 42 Hydraulic Cylinder 53 Pinion 55 Sprocket Wheel 66 Sprocket Wheel 67 Sprocket Wheel 71 Pinion 75 Sprocket Wheel 76 Chain 77 Chain

Claims (5)

[Claims] 1. A pair of inner hollow middle booms are rotatably connected to each other in an X-shape at a slightly central position, and an upper boom and a lower boom that extend and contract at their respective ends are slidable in each middle boom. Each end of the lower boom is axially mounted on the base at intervals, and each end of the upper boom is axially mounted on the lift base at intervals, and the upper boom is moved up and down. A lifting device capable of vertically moving while vertically maintaining the lifting platform by sliding the lower boom and the lower boom in synchronization with each other from the middle boom. A pair of sprocket wheels are provided at the center of rotation of the pair of middle booms. Rotatably support the sprocket wheel, connect a sprocket wheel to one end of each middle boom, and check the chain between the sprocket wheel at the center of rotation and the sprocket wheel at one end of the middle boom. In a mechanism for synchronizing the sliding amount of the lower boom with a sprocket wheel and a chain, the lifting device is characterized in that the sprocket wheel provided at one end of the middle boom is controlled so as to have a difference in rotation speed. Synchronization mechanism. 2. The number of teeth of one of the sprocket wheels provided at one end of the middle boom is smaller than the number of teeth of the other sprocket wheel provided at one end of the middle boom. The synchronization mechanism of the lifting device according to item 1. 3. The number of teeth of one of the sprocket wheels provided at one end of the middle boom is set to be one tooth less than the number of teeth of the other sprocket wheel provided at one end of the middle boom. The synchronization mechanism of the lifting device according to claim 1. 4. A pair of hollow inner middle booms are rotatably connected to each other in an X shape at a slightly central position, and upper and lower booms that extend and contract at their respective ends are slidable in the middle booms. Each end of the lower boom is axially mounted on the base at intervals, and each end of the upper boom is axially mounted on the lift base at intervals, and the upper boom is moved up and down. In a lifting device that can vertically move while keeping the lifting platform horizontal by sliding the lower boom and the lower boom in synchronization with each other, rotate the pair of sprocket wheels around the center of rotation of the pair of middle booms. Connect the sprocket wheel to one end of each middle boom, and connect the sprocket wheel at the center of rotation to the sprocket wheel at one end of the middle boom. The rack is fixed in the length direction of the lower boom, the rack is pivotally supported on one end of the middle boom and the pinion is meshed with this rack, and this pinion is attached to one end of the middle boom by the sprocket wheel. Driven, these sprocket wheels, chains,
The rack and pinion are configured to synchronize the extension amount of the lower boom with respect to the middle boom, and the number of teeth of the sprocket wheel provided at one end of one middle boom is smaller than the number of teeth of the sprocket wheel provided at one end of the other middle boom. The synchronizing mechanism of the lifting device characterized by the above. 5. The number of teeth of one of the sprocket wheels provided at one end of the middle boom is set to be one less than the number of teeth of the other sprocket wheel provided at one end of the middle boom. Claim 4 to
The synchronization mechanism of the lifting device according to the item.