Outrigger device, vehicle-mounted crane, and mobile crane

Abstract

To provide an outrigger device and a vehicle-mounted crane capable of protecting a chassis frame even if the front chassis frame of a vehicle is not reinforced, and moreover, to provide a mobile crane capable of delivering the same performance regardless of the turning angle of a working machine.SOLUTION: In a mobile crane 1 mounted with an outrigger device 10, an overhang angle AF is set to +45 degrees. Therefore, a frontward overturning line FG connecting the left and right ground contact points 16 is located further forward than the revolving center CP of a vehicle-mounted crane 5. At the location, the maximum overturning moment acting when a boom 7 is located in a front region E1 becomes less than a stable moment.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an outrigger device, a vehicle-mounted crane, and a mobile crane equipped with the outrigger device.

Background Art

[0002] Conventionally, an outrigger device mounted on a truck or the like includes a base fixed to a chassis frame of a vehicle, a lateral outrigger stored in a nested manner inside the base, and a vertical outrigger fixed to the tip of the lateral outrigger in a direction along the vehicle's vertical direction and having an outrigger cylinder inside, as disclosed in Patent Document 1 below.

[0003] When using such an outrigger device, first, the lateral outrigger is horizontally pulled out from the base to the outside in the vehicle width direction, and the outrigger cylinder is extended to ground the grounding portion provided at the tip of the cylinder rod. Then, the outrigger cylinder is further extended to move the load applied to the front wheels of the vehicle to the outrigger device. By moving the load to the outrigger device that protrudes in the vehicle width direction, the reaction force against the overturning moment that attempts to overturn the vehicle is increased, ensuring the stability of the vehicle.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, a mobile crane as described in Patent Document 1 above is modified by welding a reinforcing plate to the chassis frame when mounting a vehicle-mounted crane so that the vehicle is not damaged by the suspended load. However, since such a mobile crane is manufactured by mounting a vehicle-mounted crane on a completed vehicle, various parts are attached to the vehicle during the mounting process. Therefore, before reinforcing the chassis frame, the parts attached to the reinforcement points must be removed. However, components such as engines are arranged inside the cabin in the front of the vehicle, making it difficult to perform the reinforcement.

[0006] Since the chassis frame of the cabin part is not reinforced, it is in a state of lower strength compared to the chassis frame of the part where the crane device is mounted. Therefore, when performing lifting work in the front of the vehicle, there is a risk of damaging the chassis frame even with a load that can be lifted on the side or rear of the vehicle.

[0007] Therefore, in the case of a vehicle-mounted crane, the rated load when working in the front of the vehicle is restricted compared to the rear and side of the vehicle, thereby reducing the load on the chassis frame. If, when transporting a suspended load with a mass exceeding the rated load in the front area in the side area and attempting to turn the crane device to enter the front area, the moment limiter activates, the operation of the crane device stops or an alarm is issued.

[0008] For these reasons, in almost all cases when performing work by turning the work machine, the crane device must be turned to the loading platform side, and the fact that the rated load changes depending on the turning angle of the crane device has been a factor in reducing the workability during crane operation.

[0009] In view of such circumstances, the present invention provides an outrigger device and a vehicle-mounted crane capable of protecting the chassis frame even if the chassis frame on the front side of the vehicle is not reinforced, and further aims to provide a mobile crane capable of exhibiting the same performance regardless of the turning angle of the work machine.

Means for Solving the Problems

[0010] The first invention is an outrigger device provided on the left and right sides of a vehicle-mounted crane mounted on a vehicle, When the vehicle-mounted crane performs a lifting operation in the front region, the total overturning moment, which is a moment for rotating the vehicle in a direction that generates a grounding load on the front wheels of the vehicle about an imaginary straight line connecting the grounding portions on the left and right, is defined as the combined moment of a first overturning moment acting by the mass of the front portion of the vehicle with the imaginary straight line as a boundary and a second overturning moment acting by the mass of the load at the rated load in the rear region or side region when lifting the load in the front region and the mass of the front portion of the vehicle-mounted crane with the imaginary straight line as a boundary. When the stabilizing moment, which is a moment for rotating the vehicle in a direction that generates a grounding load on the rear wheels of the vehicle about the imaginary straight line, is defined as the combined moment of a first stabilizing moment acting by the mass of the rear portion of the vehicle with the imaginary straight line as a boundary and a second stabilizing moment acting by the mass of the rear side of the vehicle-mounted crane with the imaginary straight line as a boundary, The outrigger device is characterized in that the grounding portion is grounded at a position in front of the turning center of the vehicle-mounted crane on the front side of the vehicle, and the total overturning moment is smaller than the stabilizing moment.

[0011] The second invention is an outrigger device characterized in that when the vehicle according to the first invention is viewed from above, it projects obliquely forward at a predetermined angle.

[0012] The third invention is an outrigger device characterized in that the predetermined angle is approximately 40 degrees or more and approximately 50 degrees or less on the front side of the vehicle when the direction along the vehicle width direction of the vehicle is set to 0 degrees.

[0013] The fourth invention is an outrigger device characterized in that the projecting portion provided with the grounding portion according to the second invention swings in the vertical direction of the vehicle about the base end portion, so that the attitude is changed between a stored attitude in which the grounding portion rises upward and a grounding attitude in which the grounding portion lies down to be grounded.

[0014] The fifth invention is characterized in that, as the overhanging portion described in the fourth invention, it is provided with a swing arm, furthermore, it is provided with a first link arm, a second link arm, and an actuator that expands and contracts, the base end portion of the swing arm is swingably supported around a horizontal first axis at an end in the vehicle width direction of a base fixed to the chassis frame of the vehicle, one end of the first link arm is swingably supported around a second axis parallel to the first axis above the first axis and on the center side in the vehicle width direction, one end of the second link arm is swingably supported around a third axis parallel to the first axis at the base end portion of the swing arm, and the other end is swingably supported around a fourth axis parallel to the first axis at the other end of the first link arm, one end of the actuator is swingably supported around the fourth axis at the tip of the first link arm, and the other end is swingably supported around a fifth axis parallel to the first axis on the tip side of the swing arm with respect to the third axis, The outrigger device is characterized in that the posture can be changed between the storage posture and the grounding posture by the expansion and contraction of the actuator.

[0015] The sixth invention is an outrigger device characterized in that the storage posture described in the fourth invention is a posture in which the grounding portion faces upward and the overhanging portion does not overlap with the chassis frame of the vehicle when viewed from the vehicle width direction.

[0016] The seventh invention is a vehicle-mounted crane characterized by comprising a crane device and the outrigger device according to any one of the first to sixth inventions.

[0017] The eighth invention is that the vehicle-mounted crane described in the seventh invention is mounted between the cab of the vehicle and the rear mounting, The mobile crane is characterized in that the rated load of the crane device is set equally regardless of whether it is in the front area, side area or rear area of the vehicle.

Advantages of the Invention

[0018] According to the present invention, it is possible to provide an outrigger device and a vehicle-mounted crane that can protect the chassis frame even if the chassis frame on the front side of the vehicle is not reinforced, and further, it is also possible to provide a mobile crane that can exhibit the same performance regardless of the turning angle of the working machine.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals, and redundant descriptions are omitted. Note that the drawings are schematic. Therefore, it should be noted that the relationship between the thickness and the planar dimensions, the ratio, etc. are different from the actual ones, and there are also parts where the dimensional relationships and ratios are different between the drawings. Further, the following embodiments illustrate devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention does not specify the materials, shapes, structures, displays, etc. of the components in the following embodiments.

[0021] In the following description and drawings regarding the configuration of the invention, a structure including an outrigger device and a crane device is referred to as a "vehicle-mounted crane", and an industrial machine in which the vehicle-mounted crane is mounted on a vehicle is referred to as a "mobile crane". And, unless otherwise specified, the direction in which the vehicle on which the vehicle-mounted crane is mounted advances is the "front side of the vehicle" or simply the "front side", and the direction in which it retreats is the "rear side of the vehicle" or simply the "rear side". Also, the left hand side of the driver of the vehicle in the state of sitting in the driver's seat is the "left side of the vehicle" or simply the "left side", and the right hand side is the "right side of the vehicle" or simply the "right side". Similarly, based on the driver sitting in the driver's seat, the side where the ceiling of the driver's seat is located is the "upper side", and the side where the floor is located is the "lower side". When the direction is not particularly specified, it may be the "front-rear direction of the vehicle", the "left-right direction of the vehicle", or the "up-down direction of the vehicle". Note that, unless otherwise specified, the crane device is described as being in a position where it rotates along the front-rear direction of the vehicle and faces rearward, and the boom is in a posture where it has fallen to a horizontal angle.

[0022] <Structure of Mobile Crane> First, the structure of the mobile crane 1 will be described with reference to FIG. 1. The mobile crane 1 has a vehicle-mounted crane 5 mounted on a chassis frame CF between a cab CV and a loading platform LB which is a rear mounting on a vehicle V. The vehicle-mounted crane 5 includes a crane device and an outrigger device. The crane device is configured such that the column 6 is rotatably supported about an axis along the vertical direction of the vehicle via a slewing device at the upper part of the base BE, and the base end of the boom 7 is swingably supported about an axis along the vehicle width direction at the upper end of the column 6. The boom 7 is capable of telescoping by means of a nested telescoping mechanism and is also capable of pitching by means of a hoisting cylinder 8. The column 6 is provided with a winch, and the wire rope extending from the winch is connected to a hook HO suspended from the tip of the boom 7. Although details will be described later, outrigger devices 10 are provided at both ends of the base BE in the vehicle width direction.

[0023] The chassis frame CF of the vehicle V is a ladder-shaped structure in which C-shaped members extending in the vehicle width direction and having their open sides facing each other are sandwiched by members extending in the vehicle longitudinal direction. The cab CV, the loading platform LB, the vehicle-mounted crane 5, and the outrigger devices 10 are fixed thereto. Although not shown, devices such as a muffler and an air compressor are also fixed to the chassis frame CF. In particular, since the central portion of the chassis frame CF in the vehicle longitudinal direction is the position where the vehicle-mounted crane 5 is fixed, a reinforcing member 9 is fixed thereto. Note that the reinforcing member 9 is not fixed within the range where the cab CV is provided. This is because the installation work of the vehicle-mounted crane 5 is carried out after the completion of the vehicle V, but at the time of installation, large and important components such as the engine are already mounted inside the cab CV, making it difficult to fix the reinforcing member 9 later.

[0024] When the vehicle V is an electric vehicle, a plurality of batteries BA may be mounted below the chassis frame CF. The batteries BA are arranged to have a width substantially the same as the vehicle width in order to increase the cruising range of the vehicle V. In the present embodiment, wide batteries BA are arranged side by side in the vehicle longitudinal direction, but there may also be cases where a large number of smaller batteries are arranged. In such cases, the batteries BA are arranged in a state where they overlap the outrigger devices 10 in the vertical direction.

[0025] <Structure of the Outrigger Device> Next, referring to FIGS. 2 to 4, the outrigger device 10 mounted on the mobile crane 1 will be described. Note that the outrigger devices 10 are provided on each of the right and left sides of the vehicle. Since the structures on the left and right are the same, in the following description, only the outrigger device provided on the right side of the vehicle will be described, and the description of the outrigger device provided on the left side of the vehicle will be omitted. Although details will be described later, in the present embodiment, the outrigger device 10 is installed at a predetermined angle inclined from the vehicle width direction toward the front side of the vehicle.

[0026] The outrigger device 10 includes a base 11, a swing arm 12, a first link arm 13, a second link arm 14, and a base BE to form both lever mechanisms. And an outrigger cylinder 15 is provided as an actuator for operating both of these lever mechanisms. Further, at the tip of the swing arm 12, a grounding portion 16 is supported around an axis along the vehicle longitudinal direction. Note that the swing arm 12 is a projecting portion that projects in the vehicle width direction when its posture changes.

[0027] The base 11 is a C-shaped member in a top view, whose lower part is longer in the vehicle width direction than the upper part and projects outward in the vehicle width direction, and is fixed to the right end of the base BE. In both lever mechanisms, it is a fixed joint that does not operate.

[0028] The swing arm 12 is provided with a clamping plate 12A that protrudes toward the center in the vehicle width direction when in the stored posture shown in FIG. 2 at its tip, and is a box-shaped member having a length of about 80% of the vehicle width. Note that the length of the swing arm 12 may be set for each vehicle in order to adjust the grounding position of the grounding portion 16 described later. The swing arm 12 is the first swing joint in both lever mechanisms, and its base end portion is swingably supported around a first axis 21 that is inclined toward the front side of the vehicle at a predetermined angle with respect to the vehicle longitudinal direction on the lower side of the base 11.

[0029] Further, as shown in FIG. 4, the swing arm 12 is provided with a telescopic mechanism in which the inner arm 17 is stored. A fixing pin 18 for fixing the telescopic state is provided at the tip of the swing arm 12. Although not shown, it fits into a through hole formed in the inner arm 17 along the longitudinal direction of the vehicle, and holds the state where the inner arm 17 projects. Further, at the tip of the inner arm 17, a grounding portion 16 is swingably supported around a shaft 19 parallel to the first shaft 21.

[0030] The first link arm 13 is a plate material having substantially the same length as the vertical direction of the base BE, and one is provided on each of the front side and the rear side of the vehicle inside the base portion 11. In both lever mechanisms, it is the second swing joint, and the base end portion is swingably supported around a second shaft 22 parallel to the first shaft 21 on the upper side of the base portion 11.

[0031] The second link arm 14 is a plate material having a length approximately 1.5 times that of the first link arm 13, and two are provided so as to sandwich the swing arm 12 and the first link arm 13. In both lever mechanisms, it is a connecting joint, and the base end portion is swingably supported around a third shaft 23 parallel to the first shaft 21 at the base end portion of the swing arm 12, and the tip end portion is swingably supported around a fourth shaft 24 parallel to the first shaft 21 at the other end of the first link arm 13.

[0032] The outrigger cylinder 15 is a double-acting rod cylinder in which a rod having a length approximately twice the length in the vertical direction of the base BE is fitted into a cylinder tube having substantially the same length as the length in the vertical direction of the base BE. Although it is not an element constituting a part of both lever mechanisms, the head side end portion of the cylinder tube is swingably supported around the fourth shaft 24 at the tip end portion of the first link arm 13, and the tip end portion of the cylinder rod is swingably supported around a fifth shaft 25 parallel to the first shaft 21 at the portion of the clamping plate 12A protruding from the swing arm. When the rod extends, both lever mechanisms are swung to change the posture of the swing arm 12.

[0033] As shown in Fig. 2, when the outrigger cylinder 15 is most shortened, the outrigger device 10 is in a stored posture where the grounding part 16 faces upward and the swing arm 12 and the outrigger cylinder 15 are parallel along the vehicle's vertical direction. When the outrigger cylinder 15 extends from the stored posture, the grounding part 16 moves downward under the vehicle through an arc orbit centered on the swing axis of the swing arm 12 and grounds.

[0034] If the first link arm 13 and the second link arm 14 are not provided and the outrigger cylinder 15 is directly supported by the base BE, when the swing arm 12 is lowered to a certain angle, the outrigger cylinder 15 interferes with the swing arm 12 and the operation stops. Therefore, measures such as making the swing arm 12 in a zigzag shape are necessary. In this embodiment, by configuring both lever mechanisms with the swing arm 12, the first link arm 13, and the second link arm 14, the distance between the base end side of the outrigger cylinder 15 and the swing arm 12 is fixed, and interference between the swing arm 12 and the outrigger cylinder 15 is prevented until the grounding part 16 reaches the grounding angle.

[0035] <Deployment and storage of the outrigger device> Continuing to refer to Figs. 2 to 4, the operation when deploying and storing the outrigger device 10 will be described. The outrigger device 10 in the initial state is in a stored posture for the vehicle V to travel, as shown in Fig. 2. When the outrigger device 10 is in the stored posture, the grounding part 16 is located closer to the vehicle center side than the right end of the vehicle V. That is, the width between the left and right grounding parts 16 is narrower than the vehicle width of the vehicle V.

[0036] After the mobile crane 1 stops at the working position, as shown in Fig. 3, extend the outrigger cylinder 15 until it is in a substantially horizontal position. In this state, pull out the fixing pin 18 from the through-hole that fixes the inner arm 17 in the retracted position. Then, pull out and extend the inner arm 17 to the intermediate extended position or the maximum extended position set by the position where the fixing pin is inserted into the through-hole, insert the fixing pin 18 into the through-hole, and fix the inner arm 17 again.

[0037] After that, as shown in Fig. 4, extend the outrigger cylinder 15 again, turn the swing arm 12 downward, and ground the grounding part 16. After the grounding part 16 touches the ground, further extend the outrigger cylinder 15 to move the load from the traveling device of the vehicle V to the swing arm 12. At this time, adjust the extension amount of the left and right outrigger cylinders 15 so that the front wheels FW of the vehicle V shown in Figs. 1 and 5 slightly touch the ground, are in a state where almost no load is applied, and the vehicle body is horizontal.

[0038] When storing the outrigger device 10 after the work is completed, first shorten the outrigger cylinder 15 to move the load from the swing arm 12 to the traveling device of the vehicle V. Then, shorten the outrigger cylinder 15 until the swing arm 12 is in a horizontal position, and store the inner arm 17. After storing the inner arm 17, shorten the outrigger cylinder 15 until the swing arm 12 is in the stored position along the vertical direction of the vehicle. That is, perform the operation opposite to the deployment.

[0039] <Area performance> Next, with reference to Fig. 5, explain how to set the rated load (hereinafter referred to as area performance) for each slewing position of the boom 7 of the vehicle-mounted crane 5 due to the structure in which the extending direction of the outrigger device 10 is inclined from the vehicle width direction to the front side of the vehicle. In the following description, the region sandwiched by the line connecting from the turning center of the vehicle-mounted crane 5 to the grounding portions 16 of the left and right outrigger devices 10 is referred to as the "front region E1", the region sandwiched by the line connecting the ground contact points P1 and P2 of the left and right rear wheels RW is referred to as the "rear region E2", the region sandwiched by the line connecting to the left grounding portion 16 and the line connecting to the ground contact point P2 of the left rear wheel is referred to as the "left region E3", and the region sandwiched by the line connecting to the right grounding portion 16 and the line connecting to the ground contact point P1 of the right rear wheel is referred to as the "right region E4". When explaining the extension angle of the outrigger device 10, a straight line along the vehicle width direction with the base 11 of the outrigger device 10 as the origin is defined as 0 degrees, and the inclination on the front side of the vehicle is defined as a positive angle.

[0040] First, the regional performance in the left region E3 and the right region E4, which are the side regions, will be described. When performing crane operations in these turning regions, when the boom 7 is turning to the left front side of the vehicle, loads are applied to the outrigger device 10 on the left side of the vehicle, the front wheel FW and the rear wheel RW on the left side of the vehicle. Similarly, when the boom 7 is turning to the right front side of the vehicle, loads are applied to the outrigger device 10 on the right side of the vehicle, the front wheel FW and the rear wheel RW on the right side of the vehicle. However, since such loads are mainly applied to the outrigger device 10, a load that would damage the chassis frame CF of the un-reinforced part on the front side of the vehicle does not occur. Therefore, the rated load in the left region E3 and the right region E4 can be set to the smaller of the value obtained by setting a predetermined safety factor for the strength limit of the vehicle-mounted crane 5 or the value obtained by setting a predetermined safety factor for the stability limit.

[0041] Next, the rear region E2 will be described. When working in the rear region E2, the load is mainly applied to the left and right rear wheels RW. This load acts as a downward force on the ground contact points P1 and P2 of the rear wheels RW with the turning center CP of the crane device as the fulcrum. However, since the rear wheels RW are in contact with the ground during crane operations, this force becomes a force that tries to bend the chassis frame CF into a convex shape on the lower side of the vehicle (hereinafter referred to as the bending load). When the boom 7 is located in the rear area E2, the bending load mainly acts on the range of the chassis frame CF where the reinforcing member 9 is fixed, so damage to the chassis frame CF is prevented. Therefore, the rated load of the rear area E2 can be set to either a value obtained by providing a predetermined safety factor to the strength limit of the vehicle-mounted crane 5 or a value obtained by providing a predetermined safety factor to the stability limit. Here, when performing a lifting operation in the rear area E2, since the distance from the turning center CP of the crane device to the rear tipping line RG connecting the ground contact points P2 of the left rear wheel and P1 of the right rear wheel becomes longer, it is easier to improve the stability compared to the side areas E3 and E4. However, if the rated load changes between the rear area E2 and the left area E3 and the right area E4, the operation during work becomes complicated. Therefore, generally, the rated load of the rear area E2 is set to be the same as that of the left area E3 and the right area E4.

[0042] Next, the front area E1 will be described. To clarify the operation of the outrigger device 10 according to the present embodiment, first, with reference to FIG. 6, the area performance of the front area E5 of the mobile crane 1A equipped with the outrigger device 10A with a protrusion angle of 0 degrees, which has been conventionally used, will be described. When performing a crane operation in the front area E5, since the front wheels FW are slightly in contact with the ground, the load is applied to the left and right outrigger devices 10A. However, when lifting a large-mass load or when the boom 7 is extended and the working radius is increasing, the load moves from the rear wheels RW to the front wheels FW and the front wheels FW are in contact with the ground, and a bending load is applied to the chassis frame CF located between the turning center CP of the crane device and the front wheel contact positions P3 and P4 of the front wheels FW. And since the reinforcing member 9 is not fixed to the chassis frame CF at this position, there is a risk that the chassis frame CF will be damaged by the bending load. Therefore, such a mobile crane 1A reduces the load on the chassis frame CF by restricting the rated load in the front area E5 to 25% of the rated load in other areas.

[0043] In other words, the mobile crane 1A equipped with the outrigger device 10A that has been conventionally used has a structure in which the rated load must be changed between the front side and the rear side of the vehicle with the line connecting the grounding parts 16A of the outrigger device 10A as a boundary across the turning center CP in order to prevent damage to the chassis frame CF.

[0044] On the other hand, for the mobile crane 1 equipped with the outrigger device 10 according to the present embodiment shown in FIGS. 5 and 7, the extension angle AF is set to +45 degrees. Therefore, the forward tipping line FG connecting the left and right grounding parts 16 is located on the front side of the vehicle with respect to the turning center CP of the vehicle-mounted crane 5.

[0045] Here, the stability of the mobile crane 1 related to the load transfer from the front wheels to the rear wheels is determined by the relationship between the total tipping moment and the stability moment. Therefore, the relationship between the tipping moment and the stability moment in the front region E1 and, as an example of other regions, the right region E4 will be described. Here, it is assumed that the boom 7 in each region is located at the turning angle at which the tipping moment is maximized and the stability moment is minimized. This is the turning angle with the lowest performance in each region. Specifically, in the front region E1, it is the angle at which the boom 7 and the forward tipping line FG intersect at a right angle in a top view. In the right region E4, it is the angle at which the boom 7 and the virtual straight line (hereinafter referred to as the right tipping line) FL1 connecting the grounding part 16 and the ground contact point P1 of the rear wheel RW intersect at a right angle in a top view. If the boom 7 does not intersect the forward tipping line FG or the right tipping line FL1 at a right angle, the distance related to the magnitude of the tipping moment becomes shorter, so the tipping moment becomes lower than when it intersects at a right angle. By using this turning angle as the reference for setting the rated load, the stability at other turning angles is also ensured. Note that the point PF in FIG. 4 indicates the position where the boom 7 and the right tipping line FL1 intersect at a right angle in a top view. Also, for comparison, it is assumed that the boom 7 of the conventional mobile crane 1A is located at the same turning angle, and the right tipping line in FIG. 6 is shown with the reference numeral FL2.

[0046] As shown in FIG. 7, the total overturning moment FM1 in the front region E1 is a moment (a force acting in a direction to lift the rear wheels RW) that rotates the vehicle in a direction to generate a ground load on the front wheels FW with the front tipping line FG connecting the grounding portions 16 as the axis (fulcrum). Specifically, it is the resultant moment of a first overturning moment M1 acting by the mass A [kg] of the front part of the vehicle (a part of the cabin CV and a part of the chassis frame CF) with the front tipping line FG as the boundary, and a second overturning moment M2 acting by the mass B1 [kg] of the load L lifted by the vehicle-mounted crane 5 and the mass B2 [kg] of the front part of the vehicle-mounted crane 5 (the front part of the boom 7) with the front tipping line FG as the boundary. For simplicity in the following description, virtually assume the distance from the front tipping line FG to the acting point of the first overturning moment M1 is w [m], the distance from the front tipping line FG to the acting point of the second overturning moment M2 is x [m], and the mass applied at this position is B [kg]. Therefore, the total overturning moment FM1 is given by Equation (1). In the equations used in the following description, g is the acceleration due to gravity. FM1 = M1 + M2 = gAw + gBx [N·m] ··· (1)

[0047] The stabilizing moment SM1 in the front region E1 is a moment that rotates the vehicle in a direction to generate a ground load on the rear wheels RW with the front tipping line FG as the axis (fulcrum). Specifically, it is the resultant moment of a first stabilizing moment M3 acting by the mass C1 [kg] of the rear part of the vehicle (the vehicle-mounted crane 5, the loading platform LB, a part of the chassis frame CF, and the fixtures on the chassis frame CF) with the front tipping line FG as the boundary, and a second stabilizing moment M4 acting by the mass C2 [kg] of the rear part of the vehicle-mounted crane 5 with the front tipping line FG as the boundary. For simplicity in the following description, only the stabilizing moment SM1 is used in the description. Virtually assume the distance from the front tipping line FG to the acting point of the stabilizing moment SM1 is y [m], and the mass applied at this position is C [kg]. Therefore, the stabilizing moment SM1 is given by Equation (2). SM1 = gCy [N·m] ··· (2)

[0048] If the resultant force of the first tipping moment M1 and the second tipping moment M2 is smaller than the stabilizing moment SM1, the rear wheel RW will continue to be in contact with the ground and the stability of the mobile crane 1 will be maintained. This can be expressed as relational expression (3) based on relational expressions (1) and (2). Aw + Bx < Cy ··· (3)

[0049] By the way, as described above, in the conventional mobile crane 1A, the rated load in the front region E5 is set lower than the rated loads in the rear region E6 and the side regions E7, E8. That is, the maximum value of the tipping moment received by the conventional vehicle-mounted crane 5A during lifting work is the value when lifting the load of the rated load in the rear region E6 and the side regions E7, E8. Note that the rated load in each region of the conventional mobile crane 1A is also set so as to maintain stability at the turning angle at which the tipping moment is maximized, as described above.

[0050] Here, also in the vehicle-mounted crane 5 in the present embodiment, the mass of the maximum load that can be lifted is set based on the rated load in the side regions E3, E4. Further, as shown in FIG. 4, let the mass of such a load L be D [kg] and the distance from the right tipping line FL2 to the load L be w [m]. At this time, a total tipping moment of gDz [N·m] is applied to the vehicle-mounted crane 5, and a stabilizing moment of SM2 [N·m] is applied to keep it stable. In the side region, since there is nothing other than the vehicle-mounted crane 5 and the load L outside the right tipping line FL1 that is the fulcrum of the moment, the total tipping moment FM2 is substantially the second tipping moment, and the stabilizing moment SM2 is the force acting due to the mass of the structure (substantially the entire mobile crane 1) on the side opposite to the load L with the grounding portion 16 as the boundary. FM2 = gDz [N·m] ··· (4)

[0051] Assume a case where the boom 7 of the vehicle-mounted crane 5 according to the present embodiment is turned while lifting a load L that is the rated load in the side regions E3, E4 and enters the front region. At this time, since the mass of the load L does not change (Equation (5)), from Equation (3), the total overturning moment FM1 in the front region E1 can be expressed as in Equation (6). B = D ··· (5) FM1 = gAw + gDx [N·m] ··· (6)

[0052] From the above relational expressions (1) to (6), when lifting the load L that becomes the maximum load, in order for the mobile crane 1 to maintain stability, it is necessary to satisfy Equation (7). Aw + Dx < Cy ··· (7)

[0053] Here, when the boom 7 is rotated from the right region E3 to the front region E1 without changing its length, the distance x from the front tipping line FG, which is the fulcrum of the moment in the front region E1, to the suspended load L, and the distance z from the right tipping line FL1, which is the fulcrum of the moment in the side regions E3 and E4, to the suspended load L become close values. This is because the outrigger device 10 tilts forward by 45° and extends.

[0054] Since the outrigger device 10 is supported at the vehicle-width direction ends of the base BE, the distance z in the side regions E3 and E4 is likely to be shorter than the distance x in the front region E1. However, when performing lifting work in the front region E1, the distance from the front tipping line FG to the rear end of the structure that generates the stabilizing moment also becomes longer, so the stabilizing moment SM1 becomes larger than the stabilizing moment SM2 in the side regions E3 and E4. Therefore, in the front region E1, while the total overturning moment FM1 increases, the stabilizing moment SM1 also increases, so the change in the total overturning moment caused by the difference between the distance x and the distance z is offset.

[0055] From the above, the outrigger device 10 according to the present embodiment can ground the grounding portion 16 at a position that satisfies Equation (7) by tilting forward by 45° and extending on the front side of the vehicle. Therefore, even when lifting a load with a mass that becomes the rated load in the rear region E2 and the side regions E3 and E4 in the front region E1, it is possible to maintain stability without moving the load from the rear wheels RW to the front wheels FW.

[0056] If the total overturning moment FM1 exceeds the stabilizing moment SM1, the rear wheel RW will lift off with the forward tipping line FG as the fulcrum, and the vehicle V will tip forward. However, the load that causes the vehicle V to tip forward often exceeds the strength limit of the vehicle-mounted crane 5. Therefore, by setting the rated load to the smaller of either a value obtained by providing a predetermined safety factor to the strength limit of the vehicle-mounted crane 5 or a value obtained by providing a predetermined safety factor to the stability factor of the mobile crane 1, it is possible to prevent tipping forward of the vehicle. As described above, since the total overturning moment FM1 in the front region E1 is larger than the total overturning moments in the side regions E3 and E4, if the rated load values set for the rear region E2 and the side regions E3 and E4 are used as the rated load value in the front region E1, it is also possible to prevent tipping when working in the front region E1.

[0057] In summary, in the outrigger device 10 according to the present embodiment, when the outrigger device 10 tilts forward and extends, the left and right grounding portions 16 are grounded at a position where the total overturning moment FM1, which is the sum of the first overturning moment M1 acting by the mass of the structure on the front side of the vehicle with the forward tipping line FG connecting them as the boundary and the second overturning moment M2 generated in the vehicle-mounted crane 5 when lifting the load L of the rated load in the front region E1 in the rear region E2 or the side regions E3 and E4, is smaller than the stabilizing moment SM1 acting by the mass of the structure on the rear side of the vehicle with the forward tipping line FG as the boundary (a position satisfying Equation (7)).

[0058] That is, in the mobile crane 1 according to the present embodiment, regardless of the working area, the load does not move from the rear wheel RW to the front wheel FW, and the front wheel FW maintains a slightly grounded state. Therefore, even when the boom 7 enters from the right region E4 to the front region E1 with the load L of the rated load in the side regions E3 and E4 lifted, the outrigger device 10 and the rear wheel RW support the mass of the vehicle V and the mass of the suspended load L, and continue to ensure stability. Therefore, since no load is applied to the front wheels FW, almost no bending load acts on the un-reinforced portion on the front wheel FW side of the chassis frame CF, and there is no concern that the chassis frame CF will be damaged without restricting the rated load.

[0059] Note that when the overhang angle AF approaches 0 degrees, it becomes easier to extend the outrigger device 10 longer in the vehicle width direction, and it is possible to easily maximize the area performance of the left area E3 and the right area E4. However, if the swing arm 12 is not lengthened, it becomes difficult to ground the grounding portion 16 at a position that satisfies Equation (7). Also, when the overhang angle AF approaches 90 degrees, it becomes easier to ground the grounding portion 16 in front of the front wheel grounding positions P3 and P4 when viewed from the vehicle width direction. However, since the area performance of the left area E3 and the right area E4 decreases significantly in proportion to the magnitude of the angle, it becomes difficult to maximize the rated load.

[0060] In particular, the left area E3 and the right area E4 are the areas most frequently used in the load lifting operation using the mobile crane 1, so it is necessary to suppress the decrease in area performance. Therefore, the outrigger device 10 in the present embodiment sets the overhang angle AF to 45 degrees at which the overhang length in the vehicle width direction and the overhang length in the vehicle front side are equal, so that the grounding portion 16 is grounded in front of the front wheel grounding positions P3 and P4 without making the length of the swing arm 12 extremely long.

[0061] In addition, as shown in FIG. 8, the mounting position of the vehicle-mounted crane 5 of the mobile crane 1 may be shifted to the rear of the vehicle. This is done to satisfy the legal values for the grounding load or axle load on the front wheel side, particularly when necessary. That is, when the vehicle-mounted crane 5 is mounted, the vehicle body mass increases, and the grounding load and axle load of the front wheel increase. Therefore, if left as it is, the legal load must be satisfied by reducing the loading capacity. However, by moving the mounting position to the rear wheel side, a part of the load on the front wheel can be moved to the rear wheel, and the legal standard can be satisfied without reducing the loading capacity.

[0062] Even when a vehicle-mounted crane 5 is mounted on such a vehicle, the application of the present invention is not hindered. When the mounting position of the vehicle-mounted crane 5 moves rearward, the forward tipping line FG connecting the left and right grounding portions 16 also moves rearward of the vehicle. However, in particular, the engine with a large mass is housed inside the cab CV and is located near directly above the forward tipping line FG of the mounting, so the influence on the change in moment is small, and most of the vehicle-mounted crane 5 also continues to be located on the rear side of the vehicle. Therefore, the increase in the tipping moment due to the movement of the mounting position can be suppressed to an acceptable level.

[0063] <Effect> In the outrigger device 10 according to the present invention, when the grounding portion 16 grounds on the front side of the vehicle with respect to the turning center CP of the vehicle-mounted crane 5 and the work is performed in the front region E1, the rear wheels RW continue to be grounded. Therefore, since it is not necessary to support the load with the chassis frame CF on the front side of the vehicle, it is not necessary to limit the rated load in the front region E1, and the crane device can exhibit the same performance over the entire circumference.

[0064] In particular, for the outrigger device 10A with a protrusion angle of 0 degrees as conventionally used, the lifting ability is limited in a substantially half range on the front side of the vehicle with the outrigger device 10A as the boundary. When turning is performed without operating the moment limiter in the load-suspended state, it almost always has to turn to the side of the loading platform LB. Further, since the outrigger device 10A does not have a protrusion angle, within the range where the vehicle-mounted crane 5 can turn, the front half of the vehicle becomes the front region E5, and the range where the lifting performance is limited becomes wider. On the other hand, for the outrigger device 10 according to the present embodiment, even when lifting a mass object exceeding 25% of the rated load, it is possible to turn to the front side of the vehicle without operating the moment limiter. Compared with the mobile crane 1A equipped with the conventional outrigger device 10A, the mass and range of the load that can be transported are wider, and the workability during the crane operation is improved.

[0065] In the case of the conventional nested outrigger device 10A, since the lateral outrigger is stored along the vehicle width direction inside the base BE, when the overhanging angle is not 0 degrees, the outer box must be tilted toward the loading platform LB side or the cab CV side. Therefore, in order to accommodate the lateral outrigger, the loading platform LB must be shortened or a part of the front side of the loading platform LB must be made shallower. On the other hand, in the outrigger device 10 according to the present embodiment, since the grounding portion 16 faces upward when stored, no space is required inside the base BE to store the outrigger device, and the length of the base BE in the front-rear direction can be shortened. Therefore, it is possible to set the overhanging angle without narrowing the space of the loading platform LB.

[0066] The outrigger device 10 according to the present embodiment can be installed by replacing the conventionally used outrigger device 10A. That is, since there is no need to modify the vehicle V or change the method for installation, the present invention can be applied without significantly increasing the manufacturing cost of the mobile crane 1.

[0067] <Modification> In the present embodiment, the outrigger device 10 is stored in a posture where the grounding portion 16 faces upward, but the outrigger device according to the present invention does not necessarily have to be stored in such a posture. For example, an outrigger cylinder that extends downward may be provided at the tip of the lateral outrigger cylinder that extends by a telescopic mechanism as conventionally used, and the outrigger device 10A in which the grounding portion always faces downward may be used.

[0068] When using the outrigger device 10A as conventionally used, it is sufficient if the telescopic mechanism for protruding in the vehicle width direction is provided with an overhanging angle. Further, when the overhanging angle is not set in the telescopic mechanism for protruding, the shape of the lateral outrigger cylinder may be L-shaped in a top view, and the grounding position of the grounding portion 16 may be adjusted.

[0069] In addition, the outrigger device 10 according to this embodiment includes the first link arm 13 and the second link arm 14, but the outrigger device according to the present invention is not necessarily limited to such a structure. For example, the outrigger cylinder 15 may be supported by the base 11 without including the first link arm 13 and the second link arm 14. In the case of such a structure, in order to make the outrigger device 10 assume a grounded posture while avoiding interference between the outrigger cylinder 15 and the swing arm 12, the swing arm 12 may have a non-linear shape such as a U-shape.

[0070] In this embodiment, the extension angle AF of the outrigger device 10 was +45 degrees, but it can be changed within a range of approximately 40 degrees to approximately 50 degrees depending on the length of the swing arm 12 and the mounting position of the outrigger device 10 with respect to the vehicle V.

Explanation of Reference Numerals

[0071] 1... Mobile crane, 5... Vehicle-mounted crane, 7... Boom, 9... Reinforcing member, 10... Outrigger device, 16... Grounding part, CF... Chassis frame, E1... Front area, E2... Rear area, E3... Left area, E4... Right area, L... Load, M1... First overturning moment, M2... Second overturning moment, FM1... Total overturning moment, SM1... Stabilizing moment

Claims

1. An outrigger device provided on the left and right sides of a vehicle-mounted crane mounted on a vehicle, wherein: When the vehicle-mounted crane performs a lifting operation in the front area, the total overturning moment, which is the moment to rotate the vehicle in a direction to generate a grounding load on the front wheels of the vehicle about an imaginary straight line connecting the grounding parts on the left and right, is composed of a first overturning moment acting by the mass of the front part of the vehicle with the imaginary straight line as a boundary, and a second overturning moment acting by the mass of the load of the rated load in the rear area or side area when the load is lifted in the front area and the mass of the front part of the vehicle-mounted crane with the imaginary straight line as a boundary. And the stability moment, which is the moment to rotate the vehicle in a direction to generate a grounding load on the rear wheels of the vehicle about the imaginary straight line, is composed of a first stability moment acting by the mass of the rear part of the vehicle with the imaginary straight line as a boundary and a second stability moment acting by the mass of the rear side of the vehicle-mounted crane with the imaginary straight line as a boundary. When it is set as the combined moment of, The outrigger device is characterized in that the grounding part is grounded at a position in front of the vehicle with respect to the turning center of the vehicle-mounted crane, and the total overturning moment is smaller than the stability moment.

2. The outrigger device according to claim 1, wherein when viewed from above, it projects obliquely forward at a predetermined angle.

3. The outrigger device according to claim 2, wherein the predetermined angle is approximately 40 degrees or more and approximately 50 degrees or less on the front side of the vehicle when the direction along the vehicle width direction of the vehicle is set as 0 degrees.

4. The outrigger device according to claim 2, wherein the projecting part provided with the grounding part at the tip end rocks in the vehicle vertical direction about the base end part, so that the grounding part changes its posture between a stored posture in which it rises upward and a grounding posture in which it lies down to be grounded.

5. The projecting part is provided with a swing arm, Furthermore, it is provided with a first link arm, a second link arm, and an actuator that performs a telescopic operation. The swing arm has a base end part supported swingably about a horizontal first axis at an end in the vehicle width direction of a base fixed to the chassis frame of the vehicle. One end of the first link arm is supported so as to be swingable about a second axis parallel to the first axis above the first axis and on the center side in the vehicle width direction. One end of the second link arm is supported so as to be swingable about a third axis parallel to the first axis at the base end portion of the swing arm, and the other end is supported so as to be swingable about a fourth axis parallel to the first axis at the other end of the first link arm. One end of the actuator is supported so as to be swingable about the fourth axis at the tip of the first link arm, and the other end is supported so as to be swingable about a fifth axis parallel to the first axis on the tip side of the swing arm with respect to the third axis. The outrigger device according to claim 4, characterized in that the posture can be changed between the storage posture and the grounding posture by the expansion and contraction of the actuator.

6. The outrigger device according to claim 4, characterized in that the storage posture is a posture in which the grounding portion faces upward and the protruding portion does not overlap the chassis frame of the vehicle when viewed from the vehicle width direction.

7. A vehicle-mounted crane, comprising: a crane device; and the outrigger device according to any one of claims 1 to 6.

8. The vehicle-mounted crane according to claim 7 is mounted between the cabin of the vehicle and the rear mounting. A mobile crane, characterized in that the rated load of the crane device is set equally regardless of whether it is in the front region, side region or rear region of the vehicle.

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