JP6037377B2 - Folding crane - Google Patents

Description

  The present invention relates to a folding crane in which a boom attached to the tip of a column is folded from an intermediate position and stored laterally.

  Conventionally, a column that is erected and supported on a loading platform of a vehicle such as a truck, a boom that can be bent up and down at one end of the column, and that can be bent halfway, and the vicinity of the lower end of the column There is known a folding crane including a telescopic cylinder having both ends fixed in the vicinity of one end of the boom (see, for example, Patent Document 1).

JP 2000-357019

However, in the conventional folding type crane, when the crane is deployed by extending the cylinder to rotate the boom upward, the load acting on the cylinder becomes large, and a large cylinder is required. For this reason, there is a problem that the entire crane becomes large and heavy.
In addition, since the folding crane is mounted on a vehicle such as a truck, it is necessary to fold the crane compactly when retracting the crane by rotating the boom downward by reducing the cylinder.
In addition, the deployment angle in the folding crane, that is, the pivot angle of the boom is set according to the crane application, and there is a problem that a necessary crane deployment angle according to the application must be secured. .
Therefore, the present invention has been made paying attention to the above-mentioned problem, and can reduce the load acting on the cylinder at the time of crane deployment to suppress the enlargement of the crane and ensure the necessary crane deployment angle. And it aims at providing the folding type crane which can attain size reduction at the time of crane storage.

In order to achieve the above object, a folding crane according to the present invention includes a column, a link boom, a boom, and a cylinder.
The column stands up with its lower end inserted into a crane support.
One end of the link boom is supported at the tip of the column so as to be rotatable up and down.
The boom is divided into a main boom and a sub-boom with a foldable bending portion as a center, and one end of the main boom is supported at the tip of the link boom so as to be vertically rotatable.
The cylinder is extendable, and both end portions are fixed to the column and the boom, respectively, and one end portion of the cylinder is positioned from a central position in the vertical direction of a portion of the column protruding from the crane support. Also , the other end of the cylinder is supported in the region closer to the bent portion than the center position in the longitudinal direction of the main boom .
The column boom is provided with rotation restricting means for restricting the link boom from rotating downward in the horizontal direction.

Therefore, in the folding crane of the present invention, when the cylinder is extended from the crane retracted state, the boom first pivots upward about one end portion that is the connection position with the link boom, and the boom is deployed. At this time, the link boom does not rotate. When the cylinder is further extended and the cylinder mounting position with respect to the boom coincides with the link boom axis direction, the link boom and the boom are integrated, and the link boom is connected to the column, and the upper part is centered on one end of the link boom. Rotate. That is, the crane is deployed while the pivot center positions of the boom and the link boom change with the extension length of the cylinder.
And the cylinders whose both ends are fixed to the column and the boom, respectively, one end is supported in the vicinity of the tip of the column and the other end is supported in the vicinity of the bent portion of the boom,
A large distance between the pivot center position of the boom and the cylinder mounting position with respect to the boom can be secured. Therefore, the load which acts on a cylinder at the time of crane expansion | deployment can be reduced, and the enlargement of a crane can be suppressed.
Further, when the cylinder mounting position with respect to the boom coincides with the link boom axis direction, the link boom and the boom are integrally rotated upward around one end portion of the link boom. For this reason, the horizontal shift | offset | difference of the rotation center position of a boom and the attachment position of the cylinder with respect to a column becomes small. Thereby, the deployment angle of the crane which is a rotation angle of a boom can be ensured largely.
Furthermore, in the crane retracted state where the link boom and the boom are pivoted down most, a space in which the cylinder can be arranged can be secured between the column and the boom by interposing the link boom between the column and the boom. Thereby, the compactness at the time of crane storage can be achieved.

It is a schematic side view which shows the truck which mounted the folding crane of Example 1. It is a side view which shows the storage state of the crane main body of Example 1. FIG. It is a perspective view which shows the crane support stand of Example 1. FIG. It is a figure which shows the expansion | deployment operation | movement of the crane main body of Example 1, and is a side view which shows a boom horizontal expansion | deployment state. It is a figure which shows the expansion | deployment operation | movement of the crane main body of Example 1, and is a side view which shows a boom largest expansion | deployment state. It is a side view which shows the crane main body of the folding crane of a comparative example. FIG. 7 is a side view showing a crane body of a folding crane of a comparative example, where (a) shows a horizontal deployed state and (b) shows a maximum deployed state. It is explanatory drawing explaining the balance of the moment which acts on a boom. It is a schematic diagram which shows the structure and operation | movement in the modification of the folding crane of a comparative example. It is a schematic diagram which shows the structure and operation | movement in the folding crane of Example 1. FIG.

  Hereinafter, the form for implement | achieving the folding crane of this invention is demonstrated based on Example 1 shown in drawing.

Example 1
First, the configuration will be described.
The configuration of the folding crane of the first embodiment will be described by dividing it into “the overall configuration of the vehicle to which the folding crane is applied” and “the detailed configuration of the crane body”.

[Overall configuration of vehicle with folding crane tower]
FIG. 1 is a schematic side view showing a truck on which the folding crane of the first embodiment is mounted. Hereinafter, based on FIG. 1, the whole structure of the vehicle carrying a folding crane is demonstrated.

  A truck (vehicle) T shown in FIG. 1 includes left and right front wheels FL and FR, left and right rear wheels RL and RR, a cab R, and a loading platform L. A folding crane 1 is mounted on the loading platform L near the cab R. A partition wall H is provided between the luggage mounting portion L1 of the loading platform L and the folding crane 1.

  The folding crane 1 is, for example, a crane used when loading and unloading wood from a load carrying portion L1 of a truck T. When used (working), it is unfolded as shown in FIG. 1, and when not used (stored), it is folded and stored between the cab R and the partition wall H. The folding crane 1 includes a pedestal 1A fixed on a loading platform L, a crane main body 1B supported upright on the pedestal 1A, and a crane operation unit 1C provided on the crane main body 1B.

  The pedestal 1A is a part fixed to the loading platform L, and is provided with an outrigger (not shown). The outriggers project to the side of the vehicle body when the crane body 1B is deployed to ensure work stability.

  The crane body 1B is a crane that is hydraulically deployed and retracted. Details will be described later.

  The crane operation unit 1C is provided on a side of a column 4 described later, and includes a seat 2a on which an operator sits, a control lever 2b, and a ladder 2c. The seat 2a and the control lever 2b can be tilted toward the crane body 1B.

[Detailed configuration of crane body]
FIG. 2 is a side view showing the crane main body in the retracted state, and FIG. 3 is a perspective view showing the crane support. Hereinafter, based on FIG.2 and FIG.3, the detailed structure of a crane main body is demonstrated.

  As shown in FIG. 2, the crane main body 1 </ b> B includes a crane support 3, a column 4, a link boom 5, a boom B, a cylinder 8, and a sub-cylinder 9.

The crane support 3 is a hollow pyramid steel material fixed to the pedestal 1A, and an insertion opening 32 into which the column 4 is inserted is formed in the upper end surface 31 as shown in FIG. A column receiver 33 is formed on the inner bottom surface 3 a of the crane support 3 so as to face the insertion opening 32. A bearing (not shown) for rotatably supporting the column 4 is provided inside the insertion opening 32 and the column receiver 33. A boom receiver (not shown) is provided outside the crane support 3.
Further, a pair of rack gear shafts 34 arranged in the axial direction (vertical direction) of the column 4 inserted into the crane support 3 are provided on opposite side surfaces (support table side surfaces) 3b and 3b of the crane support 3 opposite to each other. 34 penetrates each. Each side surface 3b is provided with a guide cover 35 that covers the end 34a of the rack gear shaft 34 protruding from the side surface 3b.
The rack gear shaft 34 is a metal shaft having rack gear teeth 34b formed on the side surface of the intermediate portion. Each rack gear shaft 34 can be reciprocated in the axial direction by a hydraulic system (not shown), and each end 34 a, 34 a can slide within the guide cover 35.

As shown in FIG. 2, the column 4 stands up with its lower end 41 inserted into the crane support 3 through the insertion opening 32, and one end 51 of the link boom 5 pivots up and down at the tip 42. Supported as possible. At this time, the part which protruded from the crane support stand 3 inclines with respect to a perpendicular direction. As shown in FIG. 3, the lower end (lower end tip) 41a inserted into the crane support 3 is fitted to the column receiver 33 and is supported rotatably around the axial direction by a bearing (not shown). The contact surface with respect to the insertion opening 32 is also supported so as to be rotatable about the axial direction by a bearing (not shown).
Further, a pair of pinion gears 43, 43 arranged in the axial direction (vertical direction) disposed inside the crane support 3 are formed on the peripheral surface of the lower end portion 41 of the column 4. Each pinion gear 43 is formed in an annular shape along the peripheral surface of the column 4 and meshes with the rack gear teeth 34 b of the rack gear shaft 34 that penetrates the crane support 3.
On the other hand, a shaft through hole (not shown) is formed at the distal end portion 42 of the column 4, and a first rotation support shaft together with a shaft through hole (not shown) formed in one end portion 51 of the link boom 5. J1 penetrates. Thereby, the link boom 5 can be turned up and down with respect to the column 4.

Further, a first cylinder support portion 44 is provided at an intermediate portion of the column 4 and a restriction rib (rotation restriction means) 45 is formed.
The first cylinder support portion 44 is a metal piece that protrudes laterally from a position near the front end portion 42 of the column 4, and can vertically rotate an attachment piece 81 a provided on a housing 81 that is one end portion of the cylinder 8. To support. A shaft through hole (not shown) is formed in the first cylinder support portion 44, and the first cylinder support shaft J4 passes through with a shaft through hole (not shown) formed in the mounting piece 81a of the cylinder 8. . Thereby, the cylinder 8 can be turned up and down with respect to the column 4.
The “position in the vicinity of the tip end portion 42” is a region on the tip end portion 42 side of the column 4 from the center position in the vertical direction of the portion protruding from the crane support 3.
The restriction rib 45 is a metal piece that is disposed between the first rotation support shaft J1 and the first cylinder support portion 44 and protrudes laterally in the horizontal direction. The restriction rib 45 interferes with the lower side surface 53 of the link boom 5 and restricts the link boom 5 from rotating below the horizontal direction.

  The link boom 5 is a long metal member. As shown in FIG. 2, one end 51 is supported by the column 4 so as to be pivotable up and down. The one end 61 is supported so as to be rotatable up and down. Here, a shaft through hole (not shown) is formed in the tip 52 of the link boom 5 similarly to the one end 51, and a shaft through hole (not shown) formed in the one end 61 of the main boom 6. At the same time, the second rotation support shaft J2 penetrates. Thereby, the main boom 6 can be rotated up and down with respect to the link boom 5.

Further, the distance between the first rotation support shaft J1 (the rotation center position of the link boom 5 with respect to the column 4) and the second rotation support shaft J2 (the rotation center position of the main boom 6 with respect to the link boom 5). The dimension W1 is set to a size that allows the cylinder 8 to be disposed between the column 4 and the main boom 6 when the crane body 1B is in the retracted state.
Here, “the crane main body 1B is in the retracted state” is a state in which the link boom 5 and the main boom 6 are rotated maximum downward (see FIG. 2). In addition, the maximum downward rotation state of the link boom 5 is a horizontal state regulated by the regulation rib 45. Further, the maximum downward rotation state of the main boom 6 is a state in which the main boom 6 is bent substantially at a right angle with respect to the link boom 5.

  The boom B can be bent at an intermediate position, and is divided into a main boom 6 and a sub-boom 7 around the bent portion.

  As shown in FIG. 2, the main boom 6 has one end 61 supported by the link boom 5 so as to be rotatable up and down, and a tip end 62 supported at one end 71 of the sub boom 7 so as to be rotatable up and down. . Here, a shaft through hole (not shown) is formed in the tip end portion 62 of the main boom 6 similarly to the one end portion 61, and together with a shaft through hole (not shown) formed in the one end portion 71 of the sub boom 7. The third rotation support shaft J3 penetrates. Thereby, the sub boom 7 can be turned up and down with respect to the main boom 6. The third rotation support shaft J3 is a bent portion of the boom B.

Furthermore, a second cylinder support portion 63 and a third cylinder support portion 64 are provided at the intermediate portion of the main boom 6.
The second cylinder support portion 63 is a metal piece that protrudes laterally from a position in the vicinity of the front end portion 62 of the main boom 6 and supports the rod front end 82a that is the other end portion of the cylinder 8 so as to be vertically rotatable. A shaft through hole (not shown) is formed in the second cylinder support portion 63, and the second cylinder support shaft J5 passes through with a shaft through hole (not shown) formed in the rod tip 82a of the cylinder 8. . Thereby, the main boom 6 can be rotated up and down with respect to the cylinder 8.
The “position near the front end portion 62” is a region closer to the front end portion 62 than the center position in the longitudinal direction of the main boom 6.
The third cylinder support portion 64 is constituted by a shaft through hole formed in the side surface of the main boom 6 and supports an attachment piece 91a provided in the housing 91 which is one end portion of the sub cylinder 9 so as to be vertically rotatable. . A third cylinder support shaft J6 passes through the third cylinder support portion 64 together with a shaft through hole (not shown) formed in the attachment piece 91a of the sub cylinder 9 disposed inside the main boom 6. Thereby, the sub cylinder 9 can be turned up and down with respect to the main boom 6.

As shown in FIG. 2, the sub boom 7 has an end 71 supported by the main boom 6 so as to be rotatable up and down, and an attachment mechanism 73 capable of suspending a lifting tool S (see FIG. 1) from the tip 72. Is provided. Here, a pin through-hole 73a is formed in the attachment mechanism 73, and a pin for suspension (not shown) penetrates with a bracket (not shown) provided on the suspension S. Thereby, the hanging tool S is suspended from the sub boom 7. The sub-boom 7 has a so-called telescopic structure, and an inner boom having an attachment mechanism 73 is accommodated inside the outer tab supported by the main boom 6 so as to appear and retract.
Furthermore, the 4th cylinder support part 74 which supports the rod front-end | tip 92a of the subcylinder 9 so that vertical rotation is possible is provided in the end (end part 71 end side) 71a of this sub boom 7. As shown in FIG. The fourth cylinder support portion 74 includes a shaft through hole formed on the side surface of the sub boom 7. A fourth cylinder support shaft J7 passes through the fourth cylinder support portion 74 together with a shaft through hole (not shown) formed in the rod tip 92a of the sub cylinder 9. Thereby, the sub boom 7 can be rotated up and down with respect to the sub cylinder 9.

The cylinder 8 is a hydraulic cylinder that is driven by a hydraulic system (not shown), and includes a cylindrical housing 81 and a piston rod 82 protruding and retracting from the housing 81. The housing 81 has an attachment piece 81a formed at the end on the column 4 side, and is supported by the first cylinder support portion 44 of the column 4 so as to be vertically rotatable. The rod tip 82a of the piston rod 82 is supported by the second cylinder support 63 of the main boom 6 so as to be rotatable up and down.
That is, the cylinder 8 has an attachment piece 81 a as one end portion supported at a position near the tip end portion 42 of the column 4 and a rod tip end 82 a as the other end portion supported at a position near the tip end portion 62 of the main boom 6. ing.

  The sub-cylinder 9 is a hydraulic cylinder driven by a hydraulic system (not shown), and includes a cylindrical housing 91 and a piston rod 92 that protrudes and retracts from the housing 91. The housing 91 is formed with an attachment piece 91 a at an end disposed inside the main boom 6, and is supported by the third cylinder support portion 64 of the main boom 6 so as to be vertically rotatable. The rod tip 92a of the piston rod 92 is supported by the fourth cylinder support portion 74 of the sub boom 7 so as to be vertically rotatable.

Next, the operation will be described.
First, the raising / lowering operation of the folding crane of Example 1 will be described, and then the configuration, operation, and problem of the folding crane of the comparative example will be described. The operation of the folding crane according to the first embodiment will be described by dividing it into “operation during crane storage”, “operation during crane deployment”, and “operation during crane rotation”.

[Rolling motion of a folding crane]
FIGS. 4 and 5 are diagrams illustrating a deployment operation of the crane body according to the first embodiment, and are a side view illustrating a boom horizontal deployment state and a boom maximum deployment state. Hereinafter, the raising and lowering operation of the folding crane will be described with reference to FIGS. 2 and 4 and 5.

  In the folding crane 1 according to the first embodiment, the crane body 1B is moved from the retracted state shown in FIG. 2 to the FIGS. It transforms to the unfolded state shown. Further, the boom B of the crane main body 1B is rotated up and down with respect to the main boom 6 in accordance with the expansion and contraction of the sub-cylinder 9, and the expanded state shown in FIG. 5 is deformed into a bent state.

(Operation accompanying expansion and contraction of cylinder 8)
In the folding crane 1 of the first embodiment, a cylinder 8 is provided between the column 4 and the main boom 6. Therefore, when the piston rod 82 enters the housing 81 of the cylinder 8 and contracts, the main boom 6 is attracted to the column 4. For this reason, when the cylinder 8 is contracted most, the main boom 6 is in a state of being rotated most downward about the second rotation support shaft J2. At this time, the main boom 6 is stabilized by contacting a boom receiver (not shown) provided on the crane support 3.

  On the other hand, the link boom 5 is interposed between the column 4 and the main boom 6 connected via a cylinder 8. Therefore, when the second boom support portion 63, which is the mounting position of the cylinder 8 with respect to the main boom 6, coincides with the axial direction of the link boom 5, the link boom 5 rotates when the main boom 6 rotates upward. The boom 6 rotates up and down as the boom 6 rotates. Further, the downward rotation of the link boom 5 is restricted to the horizontal state by the restriction rib 45. For this reason, the link boom 5 cannot rotate downward from the horizontal state. That is, when the cylinder 8 is contracted most, the link boom 5 is in a horizontal state.

  When the piston rod 82 projects from the housing 81 and the cylinder 8 extends, the projecting output of the piston rod 82 acts on the second cylinder support portion 63 of the main boom 6, and as shown in FIG. The boom 6 rotates upward about the second rotation support shaft J2. At this time, since the second cylinder support portion 63 does not coincide with the axial direction of the link boom 5, the link boom 5 is held in a horizontal state.

  Furthermore, if the piston rod 82 of the cylinder 8 protrudes and the second cylinder support part 63 of the main boom 6 coincides with the axial direction of the link boom 5, the crane body 1B will be in the horizontally deployed state shown in FIG.

  When the piston rod 82 of the cylinder 8 further protrudes, the main boom 6 is further pushed upward. The link boom 5 is pulled in the axial direction of the piston rod 82 by the main boom 6. As a result, the link boom 5 and the main boom 6 rotate integrally around the first rotation support shaft J1 while the axial directions of the second cylinder support portion 63 and the link boom 5 coincide with each other. To do. At this time, since the main boom 6 is pulled upward by a projecting output acting along the axial direction of the piston rod 82, the main boom 6 does not rotate around the second rotation support shaft J2. .

  And when the cylinder 8 is extended most, the upward rotation of the main boom 6 and the link boom 5 stops, and the crane main body 1B will be in the maximum expansion | deployment state shown in FIG. When the cylinder 8 is contracted from the maximum deployed state, the main boom 6 and the link boom 5 are rotated by the operation opposite to that when the cylinder is extended, and finally the storage state shown in FIG. 2 is obtained.

(Operation accompanying expansion and contraction of sub cylinder 9)
In the folding crane 1 according to the first embodiment, a sub cylinder 9 is provided between the main boom 6 and the sub boom 7. Here, when the piston rod 92 protrudes from the housing 91 of the sub cylinder 9, the sub boom 7 is attracted to the main boom 6. That is, when the fourth cylinder support shaft J7 is positioned below the third rotation support shaft J3 when the sub cylinder 9 is most extended, as shown in FIG. The sub-boom 7 overlaps the storage state.

  When the piston rod 92 enters the housing 91 from this retracted state and the sub cylinder 9 is contracted, the sub boom 7 rotates about the third rotation support shaft J3. At this time, the fourth cylinder support shaft J7 rotates downward, and the tip 72 of the sub boom 7 rotates upward.

  When the sub-cylinder 9 is contracted most, as shown in FIG. 4, the third rotation support shaft J3 and the fourth cylinder support shaft J7 are positioned on the same straight line, and the main boom 6 and the sub-boom 7 are substantially in the same straight line. Extends along the line.

  Subsequently, when the piston rod 92 protrudes from the housing 91 and the sub-cylinder 9 extends, as shown in FIG. 5, the tip 72 of the sub-boom 7 is lowered by its own weight around the third rotation support shaft J3. To turn. Then, when the sub cylinder 9 is extended the most, the sub boom 7 stops rotating downward, and the sub boom 7 is in the maximum bent state shown in FIG.

  In order to deform from the maximum bent state (FIG. 5) to the retracted state (FIG. 2), first, the sub cylinder 9 is contracted. As a result, the sub-boom 7 rotates about the third rotation support shaft J3, the tip end portion 72 is pulled upward, and the third rotation support shaft J3 and the fourth cylinder support shaft J7 are on the same straight line. To position. In this state, for example, by bringing the tip 72 into contact with the loading platform L of the track T, the fourth cylinder support shaft J7 is positioned below the third rotation support shaft J3. In this state, the sub-cylinder 9 is extended, and the sub-boom 7 is rotated around the third rotation support shaft J3 so that the tip end 72 side is directed upward, so that the sub-boom 7 is placed on the main boom 6 in a retracted state.

[Configuration of folding crane of comparative example]
FIG. 6 is a side view showing a crane body of a folding crane of a comparative example, showing a retracted state.

  As shown in FIG. 6, the folding crane 100 of the comparative example includes a crane support base 101, a column 102, a boom B ′, a cylinder 105, and a sub cylinder 106.

  The crane support 101 is a pedestal (not shown) mounted on a loading platform or a hollow pyramid steel material directly fixed to the loading platform. A pair of rack gear shafts 107, 107 arranged in the horizontal direction pass through the crane support base 101.

  The column 102 stands up with its lower end 102a inserted into the crane support base 101, and one end 103a of a main boom 103, which will be described later, is supported by the tip 102b so as to be vertically rotatable.

  The boom B ′ can be bent at an intermediate position, and has a main boom 103 and a sub boom 104.

  One end 103a of the main boom 103 is supported by the column 102 so as to be vertically rotatable, and one end 104a of the sub boom 104 is supported by the tip 103b so as to be vertically rotatable. At this time, the rotation support shaft J passes through a shaft through hole (not shown) formed in the one end portion 103 a of the main boom 103 and a shaft through hole (not shown) formed in the tip portion 102 b of the column 102.

  The sub boom 104 is supported at its one end 104a by the main boom 103 so as to be able to rotate up and down, and a mounting mechanism 104c capable of suspending a hanging tool (not shown) is provided at the tip 104b.

  The cylinder 105 is a hydraulic cylinder, and both ends thereof are supported by the column 102 and the main boom 103 so as to be vertically rotatable. Here, the housing attachment part 105a which is one end part of the cylinder 105 is supported by the first cylinder support part 102c provided at the lower end part x1 in the part of the column 102 protruding from the crane support base 101. . On the other hand, the rod front end 105b, which is the front end of the cylinder 105, is supported by a second cylinder support portion 103c formed at a position x2 near the one end 103a of the main boom 103.

  The sub-cylinder 106 is a hydraulic cylinder, and both ends thereof are supported by the main boom 103 and the sub-boom 104 so as to be vertically rotatable.

[Operation of folding crane of comparative example]
FIG. 7 is a side view showing a crane body of a folding crane of a comparative example, where (a) shows a horizontal deployed state and (b) shows a maximum deployed state.

  In the folding crane 100 of the comparative example, the cylinder 105 is extended to bring the crane 105 into the deployed state from the retracted state shown in FIG. 6 in which the cylinder 105 is most contracted and the main boom 103 is attracted to the column 102.

  When the cylinder 105 is extended, the extension force of the cylinder 105 (projection output of the piston rod 105c) acts on the main boom 103, and as shown in FIG. It pivots upward about a pivot support shaft J that passes through the column 102 together with the column 102.

  When the cylinder 105 is further extended from the horizontally deployed state shown in FIG. 7A, the main boom 103 rotates further upward about the rotation support shaft J as shown in FIG. 7B. To do.

[Problems of the folding crane of the comparative example]
FIG. 8 is an explanatory diagram for explaining the balance of moments acting on the boom. FIG. 9 is a schematic diagram showing a structure in a modification of the folding crane of the comparative example.

  In the folding crane 100 of the comparative example shown in FIG. 6, when the cylinder 105 extends, the cylinder extension force F <b> 1 from the cylinder 105 acts on the second cylinder support portion 103 c formed at the position x <b> 2 of the main boom 103. On the other hand, the weight F2 from the sub boom 104 or the like always acts on the tip 103b of the main boom 103. Note that the cylinder extension force F1 actually acting on the main boom 103 is a component force acting vertically upward, and the weight F2 is a component force acting vertically vertically.

  Here, since the one end 103a of the main boom 103 is supported by the column 102 so as to be rotatable up and down around the rotation support shaft J, an upward moment M1 is applied to the second cylinder support 103c of the main boom 103. Acts, and a downward moment M2 acts on the tip 103b.

Then, as shown in FIG. 8, the moment M1 at the second cylinder support portion 103c is L1, if the distance from the rotation support shaft J, which is the rotation center of the main boom 103, to the second cylinder support portion 103c is L1. It is calculated | required by following formula (1).
M1 = L1 × F1 (1)

Further, as shown in FIG. 8, the moment M2 at the distal end portion 103b is expressed by the following formula (2) if the distance from the pivot support shaft J, which is the pivot center of the main boom 103, to the distal end portion 103b is L2. Sought by.
M2 = L2 × F2 (2)

  If M2 = M1, moments acting on the two locations of the main boom 103 are balanced, and the rotation operation of the main boom 103 stops. Further, if M2> M1, since the downward moment is large, the main boom 103 rotates downward. Further, if M2 <M1, since the upward moment is large, the main boom 103 rotates upward.

On the other hand, consider a case where the support position (second cylinder support portion 103c) of the cylinder 105 in the main boom 103 is in the vicinity of the tip portion 103b. That is, this is a case where the cylinder extension force F1 ′ from the cylinder 105 acts on the second cylinder support portion 103c ′ formed in the vicinity of the distal end portion 103b of the main boom 103 (see FIG. 8). At this time, the moment M3 at the second cylinder support portion 103c ′ is expressed by the following formula (L1 ′) when the distance from the rotation support shaft J that is the rotation center of the main boom 103 to the second cylinder support portion 103c ′ is L1 ′. 3).
M3 = L1 ′ × F1 ′ (3)
Since the moment required to stop the pivoting operation of the main boom 103 is M2, if M2 = M3, the moment acting on the two locations of the main boom 103 is balanced and the pivoting of the main boom 103 is performed. Operation stops.

And based on said Formula (1)-(3), when the moment which acts on two places of the main boom 103 is balanced, cylinder extension force F1 which acts on the 2nd cylinder support part 103c, and 2nd cylinder The cylinder extension force F1 ′ acting on the support portion 103c ′ is obtained by the following formulas (4) and (5).
F1 = M2 / L1 (4)
F1 ′ = M2 / L1 ′ (5)

  Here, since L1 <L1 ′, F1> F1 ′. That is, as the distance from the rotation support shaft J, which is the rotation center of the main boom 103, to the support position of the cylinder 105 (the second cylinder support portion 103c) in the main boom 103, the second cylinder support portion 103c is increased. It can be seen that the acting cylinder extension force F1 may be small.

  On the other hand, consider a folding crane 200 schematically shown in FIG. In this folding crane 200, the support position of the cylinder 105 (first cylinder support portion 102c) in the column 102 is made closer to the tip end portion 102b of the column 102 than in the case of the folding crane 100 of the comparative example shown in FIG. . Further, the support position (second cylinder support portion 103c) of the cylinder 105 in the main boom 103 is brought closer to the tip end portion 103b of the main boom 103 than in the case of the folding crane 100 of the comparative example shown in FIG.

Here, in the folding cranes 100 and 200, since the main boom 103 rotates up and down around the rotation support shaft J, the more the main boom 103 rotates downward, the more the space between the column 102 and the main boom 103 increases. The space K that can be arranged, which is a space generated in the above, becomes narrow. However, in order to arrange the cylinder 105 appropriately, it is necessary to secure a cylinder disposition space K having a predetermined size. Therefore, based on the necessary cylinder disposition space K, the downward rotation of the main boom 103 is performed. The limit value of the moving angle is set.
On the other hand, the outer diameter of the cylinder 105 is usually larger in the housing mounting portion 105a supported by the column 102 than in the rod tip 105b. That is, in order to arrange the housing attachment portion 105a, a larger cylinder disposition space K is required than when the rod tip 105b is disposed.

  In the folding crane 200 shown in FIG. 9A, the distance from the rotation support shaft J to the support position (second cylinder support portion 103c) of the cylinder 105 in the main boom 103 is the folding crane 100 shown in FIG. It can be secured larger than the case of. Thereby, the load which acts on the cylinder 105 when rotating the main boom 103 upward can be reduced. However, in the folding crane 200, the housing mounting portion 105a is disposed in the vicinity of the rotation support shaft J. For this reason, the cylinder-placeable space K between the column 102 and the main boom 103 must be secured larger than in the case of the folding crane 100 of FIG. 6, and the downward rotation angle of the main boom 103 is restricted. It will be. Therefore, there arises a problem that the main boom 103 cannot be stored compactly compared to the folding crane 100 shown in FIG.

  In view of this, a folding crane 300 schematically shown in FIG. 9B is considered. In the folding crane 300, the intermediate portion C of the column 102 is bent, and the rotation support shaft J serving as the rotation center of the main boom 103 is horizontal with respect to the support position of the cylinder 105 (first cylinder support portion 102c). Offset in direction.

  In the folding crane 300, the main boom 103 rotates around a rotation support shaft J offset in the horizontal direction from the first cylinder support portion 102c. For this reason, even when the main boom 103 is rotated downward, a sufficiently large cylinder-placeable space K can be secured between the column 102 and the main boom 103. Thereby, the main boom 103 can be stored compactly.

  In the folding crane 300, when the cylinder 105 is extended, the main boom 103 rotates about the rotation support shaft J. At this time, the cylinder 105 has a cylinder axis direction that is a straight line connecting the support position of the cylinder 105 with respect to the column 102 (first cylinder support portion 102c) and the rotation support shaft J that is the rotation center of the main boom 103 (see FIG. The main boom 103 cannot be rotated upward (indicated by a broken line in 9 (b)).

  In other words, the cylinder extension force F1 acting on the second cylinder support portion 103c acts in the cylinder axial direction, and the moment for rotating the main boom 103 upward is the component force of the cylinder extension force F1 directed vertically upward. It will occur. However, when the cylinder axis direction coincides with a straight line connecting the first cylinder support portion 102c and the rotation support shaft J, no component force is generated in the vertical direction, and a moment for rotating the main boom 103 upward is generated. Absent. Therefore, on the basis of this “straight line connecting the support position (first cylinder support portion 102 c) of the cylinder 105 with respect to the column 102 and the rotation support shaft J that is the rotation center of the main boom 103”, The rotation angle to is restricted. Therefore, the problem that the rotation range of the main boom 103 will become narrow compared with the folding crane 100 shown in FIG.

[Operation when crane is retracted]
FIG. 10 is a schematic diagram illustrating the structure and operation of the folding crane according to the first embodiment.

  In the folding crane 1 according to the first embodiment, when the link boom 5 and the main boom 6 are fully rotated downward and the crane body 1B is in the retracted state, the link boom 5 is attached to the restriction rib 45 (see FIG. 2). The main boom 6 is held in a substantially vertical state because of interference. At this time, since the column 4 also stands up from the crane support 3, a gap corresponding to the axial length of the link boom 5 is generated between the column 4 and the main boom 6. That is, by providing the link boom 5 between the column 4 and the main boom 6, it is possible to secure the cylinder disposition space K, and the main boom 6 can be compared with the folding crane 100 shown in FIG. 6. It can be stored compactly.

In particular, in the first embodiment, the column 4 is provided with the restriction rib 45 that restricts the link boom 5 from rotating below the horizontal direction, so that a large distance between the column 4 and the main boom 6 is ensured. be able to.
That is, the link boom 5 rotates about the first rotation support shaft J1. At this time, when the axial direction of the link boom 5 coincides with the horizontal direction, the first rotation support shaft J1 and the main boom 6 are aligned. The horizontal distance from the second rotation support shaft J2, which is the rotation center position, is maximized. For this reason, the link boom 5 is held in a horizontal state by the restriction rib 45 provided on the column 4, whereby the first rotation support shaft J <b> 1 and the second rotation support shaft J <b> 2 that are both ends of the link boom 5 are horizontal. The directional distance can be maximized, the distance between the column 4 and the main boom 6 is increased, and a large cylinder-placeable space K can be secured.

Moreover, in the first embodiment, between the first rotation support shaft J1 (the rotation center position of the link boom 5 with respect to the column 4) and the second rotation support shaft J2 (the rotation center position of the boom B with respect to the link boom 5). The interval dimension W1 (see FIG. 2) is set to a size that allows the cylinder 8 to be disposed between the column 4 and the main boom 6 when the link boom 5 and the main boom 6 are fully rotated downward. ing.
That is, even if the cylinder 8 is disposed, the downward rotation of the link boom 5 and the main boom 6 is not hindered, and both the booms 5 and 6 are disposed downward while securing the cylinder disposition space K. The maximum rotation is possible.

[Operation during crane deployment]
In the folding crane 1 of the first embodiment, the mounting piece 81a of the housing 81 of the cylinder 8 is supported by the first cylinder support portion 44 in the vicinity of the front end portion 42 of the column 4, and the rod front end 82a of the piston rod 82 is the main boom 6. Is supported by the second cylinder support portion 63 in the vicinity of the tip end portion 62, which is a bent portion of the above. When the piston rod 82 extends and the extension force from the cylinder 8 acts on the second cylinder support portion 63, the main boom 6 rotates upward about the second rotation support shaft J2.

  That is, the second cylinder support portion 63 on which the extension force from the cylinder 8 acts (corresponding to a so-called power point), and the second rotation support shaft J2 serving as the center of rotation of the main boom 6 (corresponding to a so-called fulcrum). A large distance can be secured. For this reason, the extension force of the cylinder 8 necessary for rotating the main boom 6 (load acting on the cylinder 8 when the crane is deployed) becomes smaller than that of the folding crane 100 shown in FIG. There is no need to make it. For this reason, size reduction of the whole folding crane 1 can be achieved.

  When the cylinder 8 extends and the second cylinder support portion 63 of the main boom 6 coincides with the axial direction of the link boom 5, the link boom 5 and the main boom 6 are integrated together to form the first rotation support shaft. Rotate upward about J1. That is, the rotation center position in the boom B changes from the second rotation support shaft J2 to the first rotation support shaft J1.

  For this reason, a straight line connecting the first cylinder support portion 44 that is the support position of the cylinder 8 with respect to the column 4 and the first rotation support shaft J1 that is the rotation center of the boom B is substantially vertical. Thereby, the rotation range of the main boom 6 can be ensured to the same extent as the folding crane 100 shown in FIG. 6, and a required crane deployment angle can be ensured.

Until the second cylinder support portion 63 of the main boom 6 coincides with the axial direction of the link boom 5, the boom B rotates about the second rotation support shaft J2, so that the operator sitting on the seat 2a The distance to the pivot center of the boom B can be ensured relatively long.
For this reason, the boom B does not easily disturb the operator's field of view, and the crane operation can be easily performed.

[Operation during crane rotation]
In the folding crane 1 of the first embodiment, in order to rotate the column 4 around the axial direction, the rack gear shaft 34 penetrating the side surface 3b of the crane support 3 is moved in the axial direction. As a result, the pinion gear 43 meshed with the rack gear teeth 34b of the rack gear shaft 34 rotates, and the column 4 rotates.

  Here, a pair of the rack gear shaft 34 and the pinion gear 43 are provided side by side in the axial direction of the column 4. Therefore, even if the diameter of the rack gear shaft 34 is reduced, sufficient power for rotating the column 4 and sufficient braking force for regulating the rotation of the column 4 can be secured.

  Furthermore, since the pair of rack gear shafts 34 are provided side by side in the axial direction of the column 4, the horizontal direction of the crane support 3 is larger than the case where the pair of rack gear shafts 34 is provided horizontally with the column 4 interposed therebetween. Can be reduced. Therefore, even if the mounting space of the folding crane 1 is narrow, it can be mounted.

Next, the effect will be described.
In the folding crane of the first embodiment, the effects listed below can be obtained.

(1) A column 4 standing up with a lower end 41 inserted into the crane support 3;
A link boom 5 in which one end 51 is supported on the tip 42 of the column 4 so as to be vertically rotatable,
The end B of the link boom 5 is supported at one end 61 so as to be vertically rotatable, and a boom B at which a middle position (third rotation support shaft) J3 can be bent;
Extendable and retractable cylinders 8 having both ends 81a and 82a supported on the column 4 and the boom B so as to be vertically rotatable,
With
One end portion (attachment piece) 81a of the cylinder 8 is supported in the vicinity of the tip end portion 42 of the column 4, and the other end portion (rod tip end) 82a of the cylinder 8 is bent to the bent portion (third portion) of the boom B. (Rotation support shaft) A configuration in which the shaft is supported in the vicinity of J3.
For this reason, while reducing the load which acts on the cylinder 8 at the time of crane expansion | deployment and suppressing the enlargement of the crane 1, a required crane expansion | deployment angle can be ensured and compactization at the time of crane storage can be achieved. it can.

(2) The column 4 is provided with a rotation restricting means (regulatory rib) 45 for restricting the link boom 5 from rotating below the horizontal direction.
For this reason, a large cylinder-placeable space K generated between the column 4 and the boom B can be secured.

(3) Between the rotation center position (first rotation support shaft) J1 of the link boom 5 with respect to the column 4 and the rotation center position (second rotation support shaft) J2 of the boom B with respect to the link boom 5. The interval dimension W1 is set to a size that allows the cylinder 8 to be disposed between the column 4 and the boom B when the link boom 5 and the boom B are rotated maximum downward. did.
For this reason, both the link boom 5 and the boom B can be rotated downward to the maximum while securing the cylinder disposition space K between the column 4 and the boom B.

(4) A pinion gear 43 disposed inside the crane support 3 is provided on the peripheral surface of the lower end portion 41 of the column 4;
The crane support 3 is provided with a plurality of rack gear shafts 34 that are arranged side by side in the vertical direction and penetrate the support table side surface (side surface) 3 b and mesh with the pinion gear 43.
For this reason, even if the diameter of the rack gear shaft 34 is reduced, the power for rotating the column 4 and the rotational braking force can be secured, and the size of the crane support 3 in the horizontal direction can be reduced. The tower mounting space can be reduced.

  As mentioned above, although the folding crane of this invention has been demonstrated based on Example 1, about a concrete structure, it is not restricted to this Example, The summary of the invention which concerns on each claim of a claim Unless it deviates, design changes and additions are allowed.

  In the first embodiment, an example in which a pair of pinion gears 43 are provided side by side in the axial direction of the column 4 has been described. Even in this case, the pair of rack gear shafts 34 mesh with the pinion gears, so that sufficient column rotational power can be ensured even if the rack gear shaft 34 has a small diameter. Further, three or more rack gear shafts 34 may be used.

  Moreover, in Example 1, although the truck T was shown as a vehicle carrying the folding crane 1, it is not restricted to this. Even a tractor (towing vehicle) or a trailer (towed vehicle) can be applied. The folding crane 1 may be mounted on the rear part of the vehicle. Further, it may be installed on a building or on the ground surface.

T truck (vehicle)
DESCRIPTION OF SYMBOLS 1 Folding type crane 1A Pedestal 1B Crane main body 1C Crane operation part 3 Crane support stand 32 Insertion opening 34 Rack gear shaft 35 Guide cover 4 Column 41 Lower end part 42 Tip part 43 Pinion gear 44 1st cylinder support part 45 Restriction rib (turning restriction means) )
5 Link boom 51 One end portion 52 End portion 53 Lower side surface B Boom 6 Main boom 61 One end portion 62 End portion 63 Second cylinder support portion 64 Third cylinder support portion 7 Sub boom 71 One end portion 72 End portion 74 Fourth cylinder support portion 8 Cylinder 81 Housing 81a Mounting piece 82 Piston rod 82a Rod tip 9 Sub cylinder J1 First rotation support shaft J2 Second rotation support shaft J3 Third rotation support shaft J4 First cylinder support shaft J5 Second cylinder support shaft

Claims (3)

A column standing at the lower end inserted into the crane support;
A link boom supported at one end of the column so as to be pivotable up and down at the tip of the column;
A boom that is divided into a main boom and a sub boom around a foldable bending portion, and one end of the main boom is supported at the tip of the link boom so as to be vertically rotatable,
Extendable and retractable cylinders that are supported on the column and the boom so that both end portions can be vertically rotated,
With
One end portion of the cylinder is supported in a region closer to the tip end portion than a center position in the vertical direction of a portion of the column that protrudes from the crane support base, and the other end portion of the cylinder is supported in the longitudinal direction of the main boom. Support in the region on the side of the bent part from the center position in the direction ,
A folding crane characterized in that the column boom is provided with rotation restricting means for restricting the link boom from rotating downward in the horizontal direction . The folding crane according to claim 1 ,
The distance between the rotation center position of the link boom with respect to the column and the rotation center position of the boom with respect to the link boom is determined so that the column boom and the boom are rotated to the maximum when the link boom and the boom are rotated downward. A folding crane characterized in that the cylinder can be arranged between the boom and the boom. In the folding crane according to claim 1 or 2 ,
Provided on the peripheral surface of the lower end of the column is a pinion gear disposed inside the crane support,
A folding crane characterized in that a plurality of rack gear shafts are provided on the crane support table so as to penetrate the side surface of the support table in the vertical direction and mesh with the pinion gear.