Boom control devices for construction machinery

Abstract

To provide a boom control device of a construction machine which properly and safely controls operation of a multistage boom by corresponding to whether a separable front side portion is mounted in a rear side portion and is simplified in work for changing a connection destination of an extension end of a cord.SOLUTION: In a multistage boom, a front side portion having a telescopic boom member is separably mounted in a rear side portion having a base boom member and a telescopic boom member. In a boom control device, an extension end of a cord can be connected to the front side portion and an undulating cylinder undulates or lays down the multistage boom. In a state that the extension end of the cord is connected to the rear side portion and a telescopic cylinder is connected to the telescopic boom member on a foremost stage in the rear side portion, a controller determines whether the front side portion is mounted in the rear side portion on the basis of a pressure of the undulating cylinder when the multistage boom is in a prescribed undulating state and a reference condition is satisfied with respect to telescopic states of a plurality of telescopic boom members.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a boom control device that controls the operation of a multi-stage boom that is extendable and retractable in the longitudinal direction in a construction machine. [Background technology]

[0002] Patent Document 1 discloses a crane as a construction machine equipped with a multi-stage boom that can be extended and retracted in the longitudinal direction. In this crane, the multi-stage boom includes a rear section attached to an upper rotating body and a front section detachably attached to the rear section. In a crane in which the front section of the multi-stage boom can be separated from the rear section, the number of sections of the multi-stage boom differs between a state in which the front section is attached to the rear section and a state in which the front section is separated from the rear section. In a crane in which the front section of the multi-stage boom can be separated from the rear section, the front section is transported to a work site or the like in a separated state. Then, at the work site, work or the like is performed using a multi-stage boom in which the front section is attached to the rear section and the front section is attached to the rear section.

[0003] Furthermore, in Patent Document 1, a cord extends from a reel installed in the rear portion toward the front side. The extending end (distal end) of the cord from the reel can be selectively connected to either the front portion or the rear portion. When attaching the front portion to the rear portion, the extending end of the cord is detached from the rear portion and connected to the front portion. On the other hand, when separating the front portion from the rear portion, the extending end of the cord is detached from the front portion and connected to the rear portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-38072 Summary of the Invention [Problem to be solved by the invention]

[0005] In a construction machine in which the front section of a multi-stage boom can be separated from the rear section, as in Patent Document 1, the number of sections of the multi-stage boom varies depending on whether the front section is attached to the rear section, and therefore the weight and longitudinal length of the multi-stage boom vary depending on whether the front section is attached to the rear section. Therefore, there is a need for a system that can safely and appropriately control the extension and retraction of the multi-stage boom by appropriately controlling the extension and retraction of the telescopic cylinder that extends and retracts the multi-stage boom depending on whether the front section is attached to the rear section. There is also a need for a system that can safely and appropriately calculate the real-time working radius of the multi-stage boom, the real-time load (actual load) applied to the multi-stage boom, and the limit value (upper limit) of the load applied to the multi-stage boom depending on whether the front section is attached to the rear section, and then safely and appropriately control the operation of the multi-stage boom based on the calculation results.

[0006] Furthermore, in a multi-section boom in which the front section can be separated from the rear section, as described above, it is necessary to change the connection destination of the extended ends of the cords when attaching the front section to the rear section and when separating the front section from the rear section. There is a need to simplify the task of changing the connection destination of the extended ends of the cords, for example, by changing the connection destination of the extended ends of the cords when the multi-section boom is fully retracted.

[0007] The present invention has been made to solve the above-mentioned problems, and its object is to provide a boom control device for construction machinery that appropriately and safely controls the operation of a multi-stage boom depending on whether the detachable front part is attached to the rear part, and simplifies the task of changing the connection destination of the extended end of the cord. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the present invention is a boom control device for controlling the operation of a multi-stage boom, which includes a rearmost base boom member and multiple telescopic boom members that are extendable and contractable in the longitudinal direction relative to the base boom member, and a front section formed of one or more of the telescopic boom members that is detachably attached to a rear section formed of the base boom member and one or more of the telescopic boom members, the boom control device comprising: a cord extending from the rear section and having an extension end connectable to the front section; a telescopic cylinder that is selectively connectable to one of the telescopic boom members and that extends or retracts the connected telescopic boom member when telescopically operated; a hoisting cylinder that raises or lowers the multi-stage boom; and a controller that, when the extended end of the cord is connected to the rear section and the telescopic cylinder is connected to a first telescopic boom member that is the frontmost telescopic boom member in the rear section, determines whether the front section is attached to the rear section based on the pressure of the hoisting cylinder when the multi-stage boom is in a predetermined hoisting state and standard conditions are met regarding the extension and contraction states of the plurality of telescopic boom members, and controls the operation of the multi-stage boom, including extension and contraction of the multi-stage boom, based on the determination result of whether the front section is attached to the rear section. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a boom control device for construction machinery that appropriately and safely controls the operation of a multi-stage boom depending on whether a detachable front section is attached to a rear section, and simplifies the task of changing the connection destination of the extended end of the cord. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a state in which a front portion is attached to a rear portion of a multi-stage boom according to a first embodiment, and FIG. 1b is a schematic diagram showing a state in which the front portion is separated from the rear portion. [Figure 2]FIG. 2 is a schematic diagram showing the frontmost boom member in the rear section (first telescopic boom member), the rearmost boom member in the front section (second telescopic boom member), and the surrounding area of ​​the multi-section boom according to the first embodiment, with the telescopic cylinder connected to the rearmost boom member in the front section. [Figure 3] FIG. 3 is a schematic diagram showing the forward-most boom member in the rear section (first telescopic boom member), the rearmost boom member in the front section (second telescopic boom member), and the surrounding area of ​​the multi-section boom according to the first embodiment, with the telescopic cylinder connected to the forward-most boom member in the rear section. [Figure 4] FIG. 4 is a schematic diagram showing the multi-section boom according to the first embodiment, in which (a) the front section is attached to the rear section and each of the boom members (telescopic boom members) is in its most retracted state, (b) the state in which the fourth boom member is extended from (a) to its most extended state, (c) the state in which the cylinder tube of the telescopic cylinder is connected to the third boom member from (b), (d) the state in which the third boom member is extended to a predetermined retracted state from (c), (e) the state in which the fourth boom member is disconnected from the third boom member from (d) and the front section is lifted up, (f) the state in which the third boom member is retracted and the front section is separated from the rear section from (e), and (g) the state in which the third boom member is retracted from (f) to its most retracted state. [Figure 5] FIG. 5 is a schematic diagram showing a system provided with a boom control device that controls the operation of a multi-stage boom in the first embodiment. [Figure 6] FIG. 6 is a flowchart that schematically illustrates a part of an example of a process for determining the attachment state between the front portion and the rear portion by the controller in the first embodiment. [Figure 7] FIG. 7 is a flowchart that schematically shows processing other than the processing shown in FIG. 6, with respect to the determination processing of FIG. [Figure 8]FIG. 8 is a flowchart that schematically shows processing other than the processing shown in FIG. 6, regarding an example of processing by the controller to determine the attachment state between the front portion and the rear portion in the first modified example. [Figure 9] FIG. 9 is a schematic diagram showing a multi-section boom according to a first modified example, in which the front section is attached to the rear section, and the telescopic cylinder is connected to the frontmost boom member on the rear section. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will be described with reference to the drawings.

[0012] (First embodiment) First, a first embodiment, which is one of the embodiments, will be described. FIGS. 1(a) and 1(b) show the configuration of a multi-stage boom 1 of the first embodiment. As shown in FIGS. 1(a) and 1(b), the multi-stage boom 1 extends along the longitudinal direction. Here, one longitudinal side of the multi-stage boom 1 is the rear side (arrow C1 side), and the opposite side from the rear side is the front side (arrow C2 side). In a crane equipped with the multi-stage boom 1 shown in FIG. 1, a rotating body (not shown) is provided on a traveling vehicle body (not shown), and the rear end of the multi-stage boom 1 is attached to the rotating body. The multi-stage boom 1 can be raised and lowered relative to the rotating body and can rotate together with the rotating body relative to the traveling vehicle body. In addition, an attachment (not shown), such as a jib, can be attached to the front end of the multi-stage boom 1.

[0013] In this embodiment, the multi-stage boom 1 includes a rear section 2 and a front section 3. The front section 3 is separably attached to the rear section 2. Therefore, in the multi-stage boom 1, the attachment state (connection state) between the front section 2 and the rear section 2 changes between two states: a state in which the front section 3 is attached to the rear section 2 as shown in FIG. 1(a), and a state in which the front section 3 is separated from the rear section 2 as shown in FIG. 1(b).

[0014] In the multi-stage boom 1 of this embodiment, the rear section 2 includes multiple (three in this embodiment) boom members B1 to B3. Here, the i in boom member Bi (i=1, 2, 3) indicates the stage number in the multi-stage boom 1. Each of the boom members Bi extends along the longitudinal direction of the multi-stage boom 1. In the multi-stage boom 1, the rear end of boom member B1 of the rear section 2 is attached to a rotating bed. In the multi-stage boom 1, boom member B1 serves as the base boom member for the rearmost stage, and boom member B1 of the rear section 2 serves as the initial stage (first stage). In the multi-stage boom 1, boom members B2 and B3 of the rear section 2 serve as the second and third stages, respectively. In the rear section 2, each of boom members B2 and B3 is a telescopic boom member that can be extended and retracted in the longitudinal direction of the multi-stage boom 1 relative to boom member B1, which is the base boom member. When either of the boom members B2, B3 is extended or contracted in the longitudinal direction, the dimension of the rear portion 2 of the multi-stage boom 1 along the longitudinal direction changes.

[0015] Among the boom members Bi in the rear section 2, the first boom member B1 is located on the outermost side, and the boom member B3 is located on the innermost side. Among the boom members Bi in the rear section, the higher the stage number, the more inward the member is located. In the multi-section boom 1, the rear end is formed by the first boom member (base boom member) B1. In the rear section 2, the front end is formed by the boom member B3. Among the boom members Bi in the rear section 2, the higher the stage number, the more forward the front end is located. Due to the configuration as described above, in the rear section 2, the boom member B1 is one stage rearward of the boom member B2, and the boom member B3 is one stage forward of the boom member B2. In this embodiment, the boom member B3 is the frontmost boom member (first telescopic boom member) Bα in the rear section 2. When the front section 3 is separated from the rear section 2, boom member B3 (Bα) becomes the foremost section (final section) in the multi-section boom 1, and boom member B3 forms the front end of the multi-section boom 1. Therefore, when the front section 3 is separated from the rear section 2, the number of sections of the multi-section boom 1 is three.

[0016] Furthermore, in the multi-section boom 1 of this embodiment, the front section 3 includes a plurality of boom members B4 to B6 (three in this embodiment). Here, j in boom member Bj (j=4, 5, 6) indicates the stage number in the multi-section boom 1 in which the front section 3 is attached to the rear section 2. When the front section 3 is attached to the rear section 2, each of the boom members Bj extends along the longitudinal direction of the multi-section boom 1. The front section 3 is attached to the rear section 2 by connecting the rear end of boom member B4 to boom member B3 (Bα) of the rear section 2. In the multi-section boom 1 in which the front section 3 is attached to the rear section 2, the boom members B4 to B6 are the fourth, fifth, and sixth stages, respectively. Furthermore, in the multi-section boom 1 in which the front section 3 is attached to the rear section 2, each of the boom members Bj is a telescopic boom member that can be extended and contracted in the longitudinal direction of the multi-section boom 1 relative to boom member B1, which is the base boom member. Therefore, in the multi-section boom 1 in which the front section 3 is attached to the rear section 2, the longitudinal dimension of the multi-section boom 1 changes when any of the boom members B2, B3, Bj extends or contracts in the longitudinal direction. Also, in the front section 3, a boom head 5 is provided at the front end of the boom member B6.

[0017] In a multi-section boom 1 in which the front section 3 is attached to the rear section 2, the first boom section B1 is positioned outermost among the boom members Bi, Bj, and boom member B6 is positioned innermost. When the front section 3 is attached to the rear section 2, the boom members Bi, Bj with higher section numbers are positioned more inward. In a multi-section boom 1 in which the front section 3 is attached to the rear section 2, the front end is formed by the boom head 5 of boom member B6. When the front section 3 is attached to the rear section 2, the front end of the boom members Bi, Bj with higher section numbers is positioned more forward. Due to the configuration described above, in a multi-section boom 1 in which the front section 3 is attached to the rear section 2, boom member B3 is one section rearward of boom member B4, and boom member B5 is one section forward of boom member B4. Furthermore, when the front section 3 is attached to the rear section 2, boom member B6 is one stage forward of boom member B5, and becomes the forwardmost stage (final stage) boom member Bγ of the multi-stage boom 1 (front section 3). Therefore, when the front section 3 is attached to the rear section 2, the multi-stage boom 1 has six stages. Furthermore, among the boom members Bj of the front section 3 attached to the rear section 2, boom member B4 becomes the rearmost boom member (second telescopic boom member) Bβ.

[0018] A crane equipped with a multi-stage boom 1 is provided with a boom hoisting cylinder (boom hoisting cylinder) 7. One end of the boom hoisting cylinder 7 is connected to the first boom member (base boom member) B1 of the multi-stage boom 1, and the other end is connected to the rotating structure. When the boom hoisting cylinder 7 is extended or retracted, the multi-stage boom 1 is raised or lowered relative to the rotating structure, etc. The boom hoisting cylinder 7 is hydraulically extended or retracted. In a crane, for example, when the multi-stage boom 1 is fully lowered (when the boom hoisting cylinder 7 is fully retracted), the multi-stage boom 1 is extended horizontally or approximately horizontally along its longitudinal direction. In another example, when the multi-stage boom 1 is in its most lowered position, the more forward the portion of the multi-stage boom 1 is, the lower it is positioned vertically, and the more it is lowered from a position in which it is extended horizontally or approximately horizontally along the longitudinal direction.

[0019] A telescopic cylinder (boom telescopic cylinder) 10 is disposed inside the multi-section boom 1. The telescopic cylinder 10 comprises a cylinder rod 11 and a cylinder tube 12. The cylinder rod 11 is connected to the first boom member B1, which is the base boom member, via a connecting member 15 such as a connecting pin. As the cylinder tube 12 moves along the longitudinal direction of the multi-section boom 1 relative to the cylinder rod 11, the telescopic cylinder 10 extends or retracts in the longitudinal direction of the multi-section boom 1, thereby telescoping. In addition, a connecting member 16 such as a grip pin is attached to the end of the cylinder tube 12 on the cylinder rod 11 side, i.e., the rear end of the cylinder tube 12. As the telescopic cylinder 10 extends or retracts, the connecting member 16 moves together with the cylinder tube 12 along the longitudinal direction of the multi-section boom 1 relative to the cylinder rod 11 and the connecting member 15.

[0020] Additionally, an engagement hole H that can engage with the connecting member 16 is formed at the rear end of each of the boom members B2, B3, and Bj, which are telescopic boom members. In the following description, the engagement hole formed in boom member B2 will be referred to as H2, and the engagement hole formed in boom member Bk of stage number k will be referred to as Hk. When the front section 3 is attached to the rear section 2, the engagement holes H2, H3, and Hj are positioned offset from each other in the longitudinal direction, and are arranged in the following order from the rear side: H2, H3, H4, H5, and H6, regardless of the telescopic state of the multi-section boom 1. When the front section 3 is attached to the rear section 2, the front section 3 can selectively engage with any one of the engagement holes H2, H3, and Hj. Therefore, when the front section 3 is attached to the rear section 2, the cylinder tube 12 can be selectively connected to either one of the boom members (telescopic boom members) B2, B3 of the rear section 2 or the boom member (telescopic boom member) Bj of the front section 3 via the connecting member 16. Furthermore, when the front section 3 is separated from the rear section 2, the engagement holes H2, H3 are shifted from each other in the longitudinal direction and are arranged in this order from the rear side, regardless of the telescopic state of the multi-section boom 1. When the front section 3 is separated from the rear section 2, the cylinder tube 12 can be selectively engaged with either one of the engagement holes H2, H3. Therefore, when the front section 3 is separated from the rear section 2, the cylinder tube 12 can be selectively connected to either one of the boom members (telescopic boom members) B2, B3 of the rear section 2 via the connecting member 16.

[0021] When the front section 3 is attached to the rear section 2, the cylinder tube 12 is connected to one of the boom members B2, B3, or Bj. By extending or retracting the telescopic cylinder 10, the boom member (corresponding one of B2, B3, or Bj) to which the cylinder tube 12 is connected extends or retracts in the longitudinal direction of the multi-section boom 1 relative to the boom member B1. As a result, the length (dimension) of the multi-section boom 1 in the longitudinal direction changes in the multi-section boom 1 in which the front section 3 is attached to the rear section 2. Here, in the state shown in FIG. 1(a), the cylinder tube 12 is connected to boom member B6, and by extending or retracting the telescopic cylinder 10, the boom member B6 can be extended or retracted relative to the boom member B1. FIG. 1(a) also shows the boom members (telescopic boom members) B2, B3, and Bj in their fully retracted state (extension rate 0%). When extending or retracting any one of the boom members B2, B3, Bj, the cylinder tube 12 is connected to the boom member to be extended or retracted (the corresponding one of B2, B3, Bj) as described above, and the connection by the lock pin (not shown) to the boom member one stage behind the boom member to be extended or retracted (the corresponding one of B2, B3, Bj) is released.

[0022] When the front section 3 is separated from the rear section 2, the cylinder tube 12 is connected to one of the boom members B2 and B3. By extending or retracting the telescopic cylinder 10, the boom member (corresponding one of B2 and B3) to which the cylinder tube 12 is connected extends or retracts in the longitudinal direction of the multi-section boom 1 relative to the boom member B1. This changes the length (dimension) of the multi-section boom 1, which is formed only from the rear section 2. In the state shown in FIG. 1(b), the cylinder tube 12 is connected to the boom member B3, and by extending or retracting the telescopic cylinder 10, the boom member B3 can be extended or retracted relative to the boom member B1. FIG. 1(b) also shows the boom members (telescopic boom members) B2 and B3 in their fully retracted state (0% extension). When extending or retracting one of the boom members B2, B3, the cylinder tube 12 is connected to the boom member to be extended or retracted (the corresponding one of B2, B3) as described above, and the connection by the lock pin to the boom member one stage behind the boom member to be extended or retracted (the corresponding one of B2, B3) is released.

[0023] In this embodiment, a reel 21 is installed on the boom member (base boom member) B1 of the rear section 2. In the multi-stage boom 1, a cord 22 extends from the reel 21 of the rear section 2 toward the front side. A connector 23 is provided on the cord 22 at the end extending from the reel 21, i.e., at the end distal to the reel 21. In a multi-stage boom 1 in which the front section 3 is attached to the rear section 2, the connector 23 (extended end) of the cord 22 is connectable to the boom head 5 of the boom member B6 of the front section 3. In a multi-stage boom 1 in which the front section 3 is separated from the rear section 2, the connector 23 (extended end) of the cord 22 is connectable to the boom member B3 of the rear section 2. In a multi-stage boom 1 in which the front section 3 is separated from the rear section 2, the connector 23 of the cord 22 may be connectable to either the boom member B1 or B2 in the rear section 2, instead of the boom member B3. As described above, in this embodiment, the extending end (distal end) of the cord 22 from the reel 21 can be selectively connected to one of the front portion 3 and the rear portion 2.

[0024] Fig. 2 and Fig. 3 show the configuration of the foremost boom member (first telescopic boom member) Bα in the rear section 2, the rearmost boom member (second telescopic boom member) Bβ in the front section 3, and their surrounding areas. Each of Fig. 2 and Fig. 3 shows a cross section parallel or approximately parallel to the longitudinal direction of the multi-section boom 1. Fig. 2 also shows the state in which the cylinder tube 12 of the telescopic cylinder 10 is connected to the rearmost boom member B4 (Bβ) in the front section 3, with boom member B4 shown in its most contracted state (extension rate of 0%). Fig. 3 also shows the state in which the cylinder tube 12 of the telescopic cylinder 10 is connected to the foremost boom member B3 (Bα) in the rear section 2, with boom member B4 shown in its most extended state (extension rate of 100%).

[0025] As shown in Figures 2 and 3, the multi-section boom 1 of this embodiment is equipped with a detector 18. The detector 18 is attached to the cylinder tube 12 of the telescopic cylinder 10. When the telescopic cylinder 10 extends or retracts due to telescopic operation, the detector 18 moves along the longitudinal direction of the multi-section boom 1 together with the cylinder tube 12 and connecting member 16 relative to the cylinder rod 11 and connecting member 15. The detector 18 is not misaligned or is barely misaligned relative to the connecting member 16 in the longitudinal direction.

[0026] Furthermore, a detection plate D is provided at the rear end of each of the boom members B2, B3, and Bj, which are telescopic boom members, as an object to be detected by the detector 18. In each of the boom members B2, B3, and Bj, the detection plate D is not misaligned or is only slightly misaligned with respect to the engagement hole H in the longitudinal direction. In the following description, the detection plate provided on the boom member B2 will be referred to as D2, and the detection plate provided on the boom member Bk of the kth stage will be referred to as Dk. When the front section 3 is attached to the rear section 2, the detection plates D2, D3, and Dj are positioned with a longitudinal offset from each other regardless of the telescopic state of the multi-section boom 1, and are arranged in the following order from the rear side: D2, D3, D4, D5, and D6. When the front section 3 is separated from the rear section 2, the detection plates D2 and D3 are positioned with a longitudinal offset from each other regardless of the telescopic state of the multi-section boom 1, and are arranged in the following order from the rear side: D2, D3, D4, D5, and D6.

[0027] The detector 18 detects each of the detection plates D2, D3, and Dj, which are the detection targets, by proximity. When the detector 18 detects one of the detection plates D2, D3, and Dj, it does not detect any other detection plates. In other words, the detector 18 does not simultaneously detect multiple detection plates. In the example shown in FIGS. 2 and 3, the detector 18 is provided with multiple infrared sensors as proximity sensors, and each of the multiple infrared sensors emits infrared light. In this case, each infrared sensor in the detector 18 receives infrared light reflected from a corresponding one of the detection plates D2, D3, and Dj, thereby detecting the corresponding detection plate that reflected the infrared light. Also, in the example shown in FIGS. 2 and 3, a different infrared sensor receives the reflected infrared light in the detector 18 for each of the detection plates D2, D3, and Dj. Therefore, it is possible to identify one of the detection plates D2, D3, and Dj that has been detected based on which infrared sensor in the detector 18 received the infrared light. The proximity sensor provided in the detector 18 is not limited to an infrared sensor, but may be a magnetic sensor or the like.

[0028] When the detector 18 detects one of the detection plates D2, D3, or Dj, which are the detection target, the telescopic cylinder 10 (cylinder tube 12) is connected to the telescopic boom member (corresponding to one of B2, B3, or Bj) detected by the detector 18, or is located in a position in the longitudinal direction where the detection plate can be connected to the telescopic boom member (corresponding to one of B2, B3, or Bj) detected by the detector 18 or in the vicinity thereof. In the state shown in FIG. 2, the telescopic cylinder 10 is connected to the rearmost boom member (second telescopic boom member) Bβ in the front section 3, and the detector 18 detects the detection plate Dβ (D4) attached to the boom member Bβ (B4). In the state shown in FIG. 3, the telescopic cylinder 10 is connected to the frontmost boom member (first telescopic boom member) Bα in the rear section 2, and the detector 18 detects the detection plate Dα (D3) attached to the boom member Bα (B3).

[0029] A lock pin R4 (Rβ) is provided at the rear end of the rearmost boom member B4 (Bβ) in the front section 3. In the boom member B4, the lock pin R4 (Rβ) is not misaligned or is barely misaligned in the longitudinal direction with respect to the engagement hole H4 (Hβ) and the detection plate D4 (Dβ). In addition, the frontmost boom member B3 (Bα) in the rear section is formed with multiple lock holes, including lock holes Eb3 (Ebα) and Ef3 (Efα), with which the lock pin R4 can engage. In the boom member B3, the lock hole Eb3 is located at the rear end, and the lock hole Ef3 is located forward of the lock hole Eb3. The lock pin R4 can be selectively coupled to any one of the multiple lock holes, including the lock holes Eb3 and Ef3.

[0030] When the boom member B4 (Bβ) is fully retracted (extension rate 0%), the lock pin R4 can engage with the lock hole Eb3 of the boom member B3. In addition, in a predetermined extension / contraction state of the boom member B4, in an example such as FIGS. 2 and 3, when the boom member B4 (Bβ) is fully extended (extension rate 100%), the lock pin R4 can engage with the lock hole Ef3 of the boom member B3. Note that when the boom member B4 is extended or retracted, the lock pin R4 is not engaged with either the lock hole Eb3 or Ef3. In addition, the front section 3 is separated from the rear section 2 with the lock pin R4 not engaged with either the lock hole Eb3 or Ef3.

[0031] Next, the operation of separating the front section 3 from the rear section 2 will be described with reference to FIGS. 4(a) to 4(g). The operation of separating the front section 3 from the rear section 2 is performed with the multi-stage boom 1 in a predetermined hoisting state. Here, in the predetermined hoisting state of the multi-stage boom 1, a pressure equivalent to the holding pressure of the multi-stage boom 1 acts on the hoist cylinder 7. The predetermined hoisting state of the multi-stage boom 1 corresponds to a state in which the hoist cylinder 7 is extended a predetermined amount from its fully retracted state, in which the pressure acting on the hoist cylinder 7 is zero. Therefore, the predetermined hoisting state of the multi-stage boom 1 corresponds to a state in which the multi-stage boom 1 is raised a predetermined angle from its fully lowered state. In one example, when the multi-stage boom 1 is in its fully lowered state, the multi-stage boom 1 extends horizontally or approximately horizontally along the longitudinal direction, and a state in which the multi-stage boom 1 is slightly raised from the state in which it extends horizontally or approximately horizontally along the longitudinal direction is defined as the predetermined hoisting state of the multi-stage boom 1. In another example, when the multi-stage boom 1 is in its most lowered state, the more forward the section of the multi-stage boom 1 is, the lower the vertical position will be, and the state in which the multi-stage boom 1 is extended horizontally or approximately horizontally along the longitudinal direction is defined as the predetermined elevation state of the multi-stage boom 1. The operation of separating the front section 3 from the rear section 2 is performed when the main hoisting rope, auxiliary hoisting rope, etc. are not hung on the boom head 5 and the main hook, sub hook, etc. are not suspended from the boom head 5.

[0032] To separate the front section 3 from the rear section 2, first, as shown in Figure 4(a), each of the boom members (telescopic boom members) B2, B3, Bj is brought to its most contracted state (0% extension). At this time, the connector 23 (extended end) of the cord 22 is connected to the boom member B6, which is the frontmost boom member Bγ in the front section 3. Then, the connecting member 16 is engaged with the engaging hole H4 (Hβ) of the boom member B4 (Bβ), and the cylinder tube 12 of the telescopic cylinder 10 is connected to the boom member B4, which is the rearmost boom member (second telescopic boom member) Bβ in the front section 3, via the connecting member 16. Then, when each of the telescopic boom members B2, B3, and Bj is fully retracted and the cylinder tube 12 is connected to the boom member B4 (Bβ), the connector 23 (extended end) of the cord 22 is removed from the boom member B6 of the front section 3 and connected to the boom member B3 of the rear section 2. That is, the connector 23 is removed from the position indicated by the solid line in Fig. 4(a) and connected to the position indicated by the dashed line in Fig. 4(a).

[0033] Then, as shown in FIG. 4(b), with the cylinder tube 12 connected to the boom member B4 and the extended end of the cord 22 connected to the rear section 2, the telescopic cylinder 10 is extended to extend the boom member B4 to its maximum extension state (100% extension). At this time, the lock pin R4 (Rβ) is not engaged with any of the lock holes of the boom member B3, including the lock holes Eb3 (Ebα) and Ef3 (Efα), and the telescopic cylinder 10 is extended to extend the boom member B4. When the boom member B4 reaches its maximum extension state, the lock pin R4 engages with the lock hole Ef3, connecting the boom member B4 to the boom member B3. The connection of the cylinder tube 12 to the boom member B4 is also released. Then, as shown in FIG. 4(c), after the cylinder tube 12 is contracted while it is not connected to any of the boom members B2, B3, Bj, the connecting member 16 is engaged with the engaging hole H3 (Hα) of the boom member B3 (Bα), and the cylinder tube 12 of the telescopic cylinder 10 is connected to the boom member B3, which is the frontmost boom member (first telescopic boom member) Bα in the rear section 2, via the connecting member 16.

[0034] Then, as shown in FIG. 4(d), with the cylinder tube 12 connected to the boom member B3, the telescopic cylinder 10 is extended to extend the boom member B3 to a predetermined telescopic state, such as a 50% extension rate. At this time, the connection of the boom member B3 to the boom member B2 by the lock pin is released, and the telescopic cylinder 10 is extended to extend the boom member B3. As a result, the boom member B4, which is the rearmost boom member (second telescopic boom member) Bβ in the front section 3, reaches its maximum extension state, and the boom member B3, which is the frontmost boom member (first telescopic boom member) Bα in the rear section 2, reaches its predetermined telescopic state. With the boom member B3 in its predetermined telescopic state, the lock pin R4 (Rβ) connecting the boom member B4 to the boom member B3 and the lock hole Ef3 (Efα) in which the lock pin R4 is engaged are positioned forward of the front end of the boom member B2 and are exposed. Then, as shown in Figure 4(e), when boom members B3 and B4 are each in the extended and retracted state shown in Figure 4(d), the connection of boom member B4 to boom member B3 by lock pin R4 is forcibly released, and the front portion 3 (boom member Bj) is lifted vertically upward by a crane separate from the crane on which the multi-stage boom 1 is mounted.

[0035] Then, as shown in FIG. 4(f), with the front section 3 lifted, the telescopic cylinder 10 is retracted. At this time, because the cylinder tube 12 is connected to the boom member B3, the boom member B3 (Bα) retracts from a predetermined telescopic state (for example, a state with an extension rate of 50%) in response to the retraction of the telescopic cylinder 10. As the boom member B3 retracts from the predetermined telescopic state, the front section 3 is separated from the rear section 2. Note that in FIG. 4(f), the boom member B3 is shown in a state retracted from the predetermined retracted state, for example, at an extension rate of 15%. Then, as shown in FIG. 4(g), the telescopic cylinder 10 is further retracted, and the boom member B3 is retracted to the most retracted state (a state with an extension rate of 0%), thereby completing the operation of separating the front section 3 from the rear section 2.

[0036] The work of attaching the front section 3 to the rear section 2 is performed in the reverse order of the work of separating the front section 3 from the rear section 2. That is, when separating the front section 3 from the rear section 2, the state of the multi-stage boom 1 changes in the order of Figures 4(a), 4(b), ..., 4(f), 4(g), whereas when attaching the front section 3 to the rear section 2, the state of the multi-stage boom 1 changes in the order of Figures 4(g), 4(f), ..., 4(b), 4(a). Furthermore, when attaching the front section 3 to the rear section 2, after the multi-stage boom 1 has been changed to the state shown in Figure 4(a), connector 23 (extended end) of cord 22 is removed from boom member B3 of the rear section 2 and connected to boom member B6 of the front section 3. That is, when each of the telescopic boom members B2, B3, and Bj is fully retracted and the cylinder tube 12 is connected to the boom member B4 (Bβ), the connector 23 is removed from the position shown by the dashed line in FIG. 4(a) and connected to the position shown by the solid line in FIG. 4(a). The front section 3 is attached to the rear section 2 after the multi-stage boom 1 is in the predetermined hoisted state described above. The front section 3 is attached to the rear section 2 without the main hoisting rope, auxiliary hoisting rope, etc. being slung around the boom head 5 and without the main hook, sub hook, etc. being suspended from the boom head 5.

[0037] FIG. 5 shows a system equipped with a boom control device 20 that controls the operation of the multi-section boom 1, including its extension and contraction. As shown in FIG. 5, the boom control device 20 includes the aforementioned cord 22 with a connector 23 attached to the distal end extending from the reel 21, as well as the aforementioned hoisting cylinder 7, telescopic cylinder 10, and detector 18. The boom control device 20 also includes a pressure gauge 17 and a controller 25. The pressure gauge 17 is, for example, a hydraulic pressure gauge, and is attached to the hoisting cylinder 7. The pressure gauge 17 measures the aforementioned pressure (holding pressure) acting on the hoisting cylinder 7. The pressure in the hoisting cylinder 7 changes depending on whether the front section 3 is attached to the rear section 2. The pressure in the hoisting cylinder 7 also changes depending on the extension and contraction states of the boom members (telescopic boom members) B2, B3, and Bj, and the hoisting state of the multi-section boom 1. The pressure in the boom raising / lowering cylinder 7 changes depending on whether or not the main hoisting rope, auxiliary hoisting rope, main hook, sub hook, etc. are attached to the boom head 5 of the multi-stage boom 1.

[0038] The controller 25 includes a processor and a storage medium. The processor is an integrated circuit or circuitry including a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like. Only one processor may be provided, or multiple processors may be provided. Processing in the processor is performed in accordance with a program stored in the processor or the storage medium. The storage medium also stores the processing program used by the processor, and parameters, functions, tables, and the like used in the calculations in the processor.

[0039] The controller 25 obtains the measurement results of the pressure in the hoisting cylinder 7 from the pressure gauge 17. The controller 25 also controls the extension and retraction operations of the hoisting cylinder 7 and the telescopic cylinder 10. The controller 25 also obtains information regarding the hoisting state of the multi-stage boom 1 based on the extension and retraction state of the hoisting cylinder 7. For example, the controller 25 obtains information indicating the real-time hoisting state of the multi-stage boom 1 based on the real-time extension and retraction state of the hoisting cylinder 7. This enables the controller 25 to determine whether the real-time hoisting state of the multi-stage boom 1 is the predetermined hoisting state described above.

[0040] The controller 25 acquires information indicating the extension and contraction history of each of the telescopic boom members constituting the multi-section boom 1. For example, when the front section 3 is attached to the rear section 2, the controller 25 acquires the extension and contraction history of each of the boom members (telescopic boom members) B2, B3, and Bj, and acquires information indicating the real-time extension and contraction state (extension rate, etc.) of each of the boom members B2, B3, and Bj. Similarly, when the front section 3 is separated from the rear section 2, the controller 25 acquires the extension and contraction history of each of the boom members (telescopic boom members) B2 and B3, and acquires information indicating the real-time extension and contraction state (extension rate, etc.) of each of the boom members B2 and B3. The extension and contraction history of each of the telescopic boom members can be calculated based on the history of the connection state of the cylinder tube 12 of the telescopic cylinder 10 with each of the telescopic boom members, the history of the longitudinal length of the multi-section boom 1, and the history of the extension and contraction of the telescopic cylinder 10, etc.

[0041] In one example, the controller 25 acquires the real-time extension rate of each of the telescopic boom members as information indicating the history of extension and contraction of each of the telescopic boom members. In this case, the controller 25 determines that each of the boom members (telescopic boom members) B2, B3, and Bj is in the most contracted state based on an extension rate of 0%, and determines that each of the boom members (telescopic boom members) is in the most extended state based on an extension rate of 100%. The controller 25 also determines whether or not the extension and contraction states of the multiple boom members (telescopic boom members) B2, B3, and Bj satisfy a reference condition based on information indicating the history of extension and contraction of each of the telescopic boom members constituting the multi-stage boom 1. In this embodiment, the controller 25 determines whether or not the extension and contraction states of the multiple boom members B2, B3, and Bj satisfy two reference conditions, a first reference condition and a second reference condition.

[0042] For example, the controller 25 determines that the first reference condition is satisfied with respect to the telescopic states of the multiple boom members B2, B3, and Bj based on the fact that boom member B4, which is the rearmost telescopic boom member (second telescopic boom member) Bβ in the front section 3, is in the most extended state (extension rate: 100%) and that each of the telescopic boom members other than boom member B4 (Bβ) is in the most retracted state (extension rate: 0%). Then, the controller 25 determines that the second reference condition is satisfied with respect to the telescopic states of the multiple boom members B2, B3, and Bj based on the fact that each of all of the telescopic boom members constituting the multi-stage boom 1 is in the most retracted state (extension rate: 0%). In addition, an operator or the like can input operation commands related to the operation of the multi-stage boom 1, including the extension and contraction of the multi-stage boom 1, via a user interface (not shown) or the like. The controller 25 acquires operation commands input via the user interface or the like.

[0043] The controller 25 also determines the connection destination of the connector 23 (extended end) of the cord 22. In a first example of determining the connection destination of the extended end of the cord 22, the controller 25 is capable of communicating with a device attached to the connection destination of the connector 23, and acquires information related to the device attached to the connection destination of the connector 23 based on a signal or the like transmitted from the device via the cord 22. For example, when the connector 23 (extended end) is connected to the front section 3, the controller 25 is capable of communicating with a device attached to the boom head 5 of the boom member B6 (Bγ), and when the connector 23 is connected to the rear section 2, the controller 25 is capable of communicating with a device attached to the rear section 2. Examples of devices with which the controller 25 can communicate include a switch that detects over-winding of the rope that suspends the hook from the boom head 5, and a sensor that detects parameters related to the multi-stage boom 1, such as the angle of the multi-stage boom 1 above the ground.

[0044] In a first example, the controller 25 determines the connection of the connector 23 (extended end) of the cord 22 based on information transmitted through the cord 22, including signals transmitted via the cord 22. For example, the address of the device attached to the connection destination of the connector 23 is transmitted to the controller 25 via the cord 22 by serial communication. In this case, unique addresses that are different from each other are set for the device attached to the front section 3 and the device attached to the rear section 2. Then, the controller 25 determines whether the connection destination of the connector 23 is the front section 3 or the rear section 2, based on the device address transmitted via the cord 22.

[0045] In the first example, when the extended end of cord 22 is connected to front portion 3, the transmission path of the signal from the device in cord 22 may be different from when the extended end of cord 22 is connected to rear portion 2. In this case, controller 25 determines whether connector 23 is connected to front portion 3 or rear portion 2, based on the transmission path of the transmitted signal in cord 22. In the first example, when a signal from the device is not transmitted via cord 22, such as when the device address is not acquired, controller 25 determines that a detection failure has occurred at the connection destination of the extended end of cord 22 due to a break in cord 22, a device malfunction, or the like.

[0046] In the second example, when the aforementioned device is not attached to the rear portion 2 and the connector 23 of the cord 22 is connected to the rear portion 2, the controller 25 does not communicate via the cord 22. In this case, the controller 25 determines that the connector 23 of the cord 22 is connected to the rear portion based on the fact that a signal is not transmitted via the cord 22, such as when the address of the device is not acquired. In this example, when the extended end of the cord 22 is connected to the front portion 3, a signal from the device attached to the front portion 3 is transmitted to the controller 25 via the cord 22. The controller 25 then determines whether the extended end of the cord 22 is connected to the front portion 3 based on the acquired address of the device, the signal transmission path in the cord 22, or the like. In the first and second examples described above, the controller 25 determines the connection (destination) of the connector 23 (extended end) of the cord 22 based on the presence or absence of a signal transmitted through the cord 22, the address of the device transmitted through the cord 22, and the transmission path in the cord 22 of the signal transmitted through the cord 22.

[0047] In a third example of determining the connection destination of the extended end of the cord 22, a boom length measurement unit that measures the length of the multi-stage boom 1 in the longitudinal direction is composed of the controller 25 and the cord 22. In this case, the controller 25 acquires the measurement result of the extended length of the cord 22 from the reel 21 (rear section 2) to the extended end. The controller 25 and the like calculate the length of the multi-stage boom 1 in the longitudinal direction based on the measurement result of the extended length of the cord 22. Note that when the extended end (connector 23) of the cord 22 is connected to the front section 3, the extended length of the cord 22 from the reel 21 to the extended end is different from when the extended end of the cord 22 is connected to the rear section 2, even if the above-mentioned extension history of each of the telescopic boom members (the extension and contraction states of each of the telescopic boom members) is the same. In other words, the extended length of the cord 22 changes depending on the connection destination of the extended end of the cord 22.

[0048] In the third example, the controller 25 determines the connection of the extended end of the cord 22 based on the measurement result of the aforementioned extended length of the cord 22 and the history of extension and contraction of the boom members (telescopic boom members) B2, B3 of the rear section 2 and the boom member (telescopic boom member) Bj of the front section 3 attached to the rear section 2. That is, the connection destination of the extended end of the cord 22 is determined based on the extended length of the cord 22 and the history of extension and contraction (e.g., history of extension rates) of the second stage and the stage forward of the second stage boom members B2, B3, Bj.

[0049] For example, assume that the controller 25 acquires information indicating that the extension rate of the third section is 50% and the extension rates of sections other than the third section are 0% as the extension history of each boom member (telescopic boom member). In this case, if the measured value of the extension length of the cord 22 is the same as or approximately the same as value L1, the controller 25 determines that the connection destination of the extension end of the cord 22 is the rear section 2 (boom member B3). Note that in the states shown in Figures 4(d) and 4(e), the extension length of the cord 22 is the same as or approximately the same as value L1. Then, if the extension length of the cord 22 is the same as or approximately the same as value L2, which is greater than value L1, the controller 25 determines that the connection destination of the extension end of the cord 22 is the front section 3 (boom member B6). In addition, in a third example, even if the controller 25 acquires information other than the above-mentioned information as the history of extension and contraction of each boom member (telescopic boom member), the controller 25 similarly determines the connection (connection destination) of the extended end of the cord 22 based on the measurement results of the extended length of the cord 22.

[0050] The controller 25 may make both a determination regarding the connection (destination) of the extended end of the cord 22 based on information transmitted from a device via the cord 22 (e.g., the first and second examples) and a determination based on the extended length of the cord (e.g., the third example). In this case, a priority order is set for the two determinations. If the two determinations produce different results, the controller 25 uses the determination result with the higher priority order as the determination result regarding the connection (destination) of the extended end of the cord 22. By making two determinations, even if a detection error occurs regarding the destination of the extended end of the cord 22 in one of the two determinations, the destination of the extended end of the cord 22 can be appropriately determined by the other of the two determinations.

[0051] The controller 25 acquires the detection results of the detection plates D2, D3, and Dj, which are the objects to be detected by the detector 18. Furthermore, the controller 25 determines the connection between each of the boom members (telescopic boom members) B2, B3, and Bj and the cylinder tube 12 of the telescopic cylinder 10, based on the detection results of the detector 18, etc. When determining the connection between each of the boom members B2, B3, and Bj and the cylinder tube 12, it determines whether the cylinder tube 12 is connected to any of the boom members B2, B3, and Bj, and if the cylinder tube 12 is connected to any of the boom members B2, B3, and Bj, it determines to which of the boom members B2, B3, and Bj the cylinder tube 12 is connected.

[0052] Furthermore, when determining whether each of the boom members B2, B3, and Bj is connected to the cylinder tube 12, the determination is made using at least one of the following: the operation history of the connecting member 16, the extension / retraction history of the telescopic cylinder 10, and the longitudinal length history of the multi-section boom 1, in addition to the detection results of the detector 18. In one example, the controller 25 determines that the telescopic cylinder 10 is connected to the boom member (telescopic boom member) Bk based on the fact that the detector 18 has continuously detected the detection plate Dk of the boom member Bk of the stage number k over time while the telescopic cylinder 10 is being extended or retracted. In another example, the controller 25 determines that the telescopic cylinder 10 is connected to the boom member (telescopic boom member) Bk based on the fact that the detector 18 has detected the detection plate Dk of the boom member Bk of the stage number k, and the connecting member 16 has been actuated to engage with the engagement hole Hk of the boom member Bk.

[0053] The controller 25 determines the attachment state (connection state) between the front section 3 and the rear section 2 based on the determination result of the connection (connection destination) of the extended end (connector 23) of the cord 22, the determination result of the connection of the cylinder tube 12 of the telescopic cylinder 10 to each of the boom members (telescopic boom members) B2, B3, Bj, the determination result of the hoisting state of the multi-section boom 1, the determination result of whether the telescopic states of the multiple boom members (telescopic boom members) B2, B3, Bj satisfy the standard conditions, and the measurement result of the pressure in the hoisting cylinder 7 using the pressure gauge 17. At this time, it determines whether the front section 3 is attached to the rear section 2 or not, and determines whether the front section 3 is attached to the rear section 2 as shown in Figure 1(a) or whether the front section 3 is separated from the rear section 2 as shown in Figure 1(b).

[0054] 6 and 7 show an example of a process for determining the attachment state between the front section 3 and the rear section 2 by the controller 25. FIG. 6 shows a portion of the process, and FIG. 7 shows the process other than that shown in FIG. 6. The determination process of FIGS. 6 and 7 is repeatedly performed over time while the controller 25 is controlling the operation of the multi-section boom 1. When the determination process of FIGS. 6 and 7 starts, the controller 25 determines whether the connector 23 (extended end) of the cord 22 is connected to the front section 3 (S101). The connection destination of the connector 23 is determined in the same manner as any of the above-described examples, including the first to third examples. If the connector 23 is connected to the front section 3 (S101—Yes), the controller 25 determines that the front section 3 is attached to the rear section (S102). In this case, it is determined that boom member B6 (Bγ) is the most forward section of the multi-section boom 1, and the multi-section boom 1 is determined to be the sixth section. If the connector 23 is not connected to the front portion 3 (S101-No), the controller 25 determines whether the connector 23 (extended end) of the cord 22 is connected to the rear portion 2 (S103).

[0055] If the connector 23 is connected to the rear section 2 (S103-Yes), the controller 25 determines whether or not the cylinder tube 12 of the telescopic cylinder 10 is connected to any of the telescopic boom members (boom members B2, B3, Bj) (S104). If the cylinder tube 12 is not connected to any of the telescopic boom members (S104-No), the controller 25 ends the process without determining the attachment state between the front section 3 and the rear section 2. In this case, the previous determination result regarding the attachment state between the front section 3 and the rear section 2 is maintained. On the other hand, if the cylinder tube 12 is connected to any of the telescopic boom members (S104-Yes), the controller 25 determines whether or not any of the boom members B4 to B6 of the front section 3 is the connection destination of the cylinder tube 12 (S105). If the connection destination of the cylinder tube 12 is any of the boom members B4 to B6 (S105-Yes), the controller 25 determines that the front section 3 is attached to the rear section 2 (S106). However, in this case, although the front section 3 is formed by the boom members B4 to B6, the controller 25 determines that the boom member B4 (Bβ) is the frontmost section of the multi-section boom 1 (S107). Therefore, the multi-section boom 1 is determined to have four sections.

[0056] If the connection destination of the cylinder tube 12 is other than the boom members B4 to B6 (No in S105), the controller 25 determines whether the connection destination of the cylinder tube 12 is the boom member B3 (Bα), which is the foremost section in the rear section 2 (S108). If the connection destination of the cylinder tube 12 is not the boom member B3 (Bα) (No in S108), the controller 25 determines that the connection destination of the cylinder tube 12 is the boom member B2. In other words, it determines that the boom member is connected to a telescopic boom member that is rearward of the boom member B3 (Bα) in the rear section 2. Then, the controller 25 determines that the front section 3 is separated from the rear section 2 (S109). In this case, it is determined that the boom member B3 (Bα) is the foremost section in the multi-section boom 1, and the multi-section boom 1 is determined to have three sections. Furthermore, if the connector 23 is not connected to the rear section 2 in S103 (S103-No), the controller 25 determines that a detection failure has occurred with respect to the connection destination of the connector 23 of the cord 22 (S110).

[0057] Furthermore, if the connection destination of the cylinder tube 12 is boom member B3 (Bα) in S108 (S108-Yes), the controller 25 determines whether the hoisting state of the multi-stage boom 1 is the predetermined hoisting state described above (S111). If the multi-stage boom 1 is not in the predetermined hoisting state (S111-No), the controller 25 does not determine the attachment state between the front section 3 and the rear section 2, and the previous determination result for the attachment state between the front section 3 and the rear section 2 is maintained. If the multi-stage boom 1 is in the predetermined hoisting state (S111-Yes), the controller 25 determines whether the real-time extension and retraction states of the multiple boom members (telescopic boom members) B2, B3, Bj satisfy the second reference condition described above (S112). If the second standard condition is not satisfied (S112-No), the controller 25 determines whether the real-time extension / retraction states of the multiple boom members (telescopic boom members) B2, B3, and Bj satisfy the first standard condition (S113). At this time, as described above, it is determined whether the first standard condition and the second standard condition are satisfied with respect to the extension / retraction states of the boom members B2, B3, and Bj. If the first condition is not satisfied (S113-No), the controller 25 does not determine the attachment state between the front section 3 and the rear section 2, and the previous determination result regarding the attachment state between the front section 3 and the rear section 2 is maintained.

[0058] When the real-time extension / retraction state of the boom members B2, B3, and Bj satisfies the first criterion condition (S113-Yes) and when the real-time extension / retraction state satisfies the second criterion condition (S112-Yes), the controller 25 determines whether the real-time pressure of the boom hoisting cylinder 7 is within a first pressure range (S114). The first pressure range includes a pressure value (first pressure value) P1 but does not include a pressure value (second pressure value) P2 that is smaller than the pressure value P1. In one example, using a value ΔP, a pressure range equal to or greater than the pressure value P1-ΔP and equal to or less than the pressure value P1+ΔP is set as the first pressure range. In this case, the difference between the pressure values ​​P1 and P2 is greater than twice the value ΔP. If the pressure in the boom lifting cylinder 7 is within the first pressure range (S114-Yes), the controller 25 determines that the front section 3 is attached to the rear section 2 (S106) and determines that the boom member B4 (Bβ) is the frontmost section of the multi-stage boom 1 (S107).

[0059] On the other hand, if the pressure is not within the first pressure range (S114—No), the controller 25 determines whether the real-time pressure of the elevation cylinder 7 is within a second pressure range (S115). The second pressure range is outside the first pressure range and includes the aforementioned pressure value (second pressure value) P2. Therefore, the second pressure range does not include the pressure value P1. In one example, using the aforementioned value ΔP, a pressure range equal to or greater than the pressure value P2—ΔP and equal to or less than the pressure value P2+ΔP is set as the second pressure range. If the pressure of the elevation cylinder 7 is within the second pressure range (S115—Yes), the controller 25 determines that the front section 3 is separated from the rear section 2 (S109). On the other hand, if the pressure is not within the second pressure range (S115-No), the controller 25 does not determine the attachment state between the front portion 3 and the rear portion 2, and the previous determination result regarding the attachment state between the front portion 3 and the rear portion 2 is maintained.

[0060] In one example, if the connector 23 is not connected to the front section 3 in S101 (S101-No), the controller 25 performs the process of S104 without performing the process of S103. In this case, if the connector 23 is not connected to the front section 3 in S101 (S101-No), the controller 25 determines that the connector 23 is connected to the rear section 2. In another example, if the connection destination of the cylinder tube 12 is other than the boom members B4 to B6 in S105 (S105-No), the controller 25 performs the process of S111 without performing the process of S108. In this case, if the connection destination of the cylinder tube 12 is other than the boom members B4 to B6 in S105 (S105-No), the controller 25 determines that the connection destination of the cylinder tube 12 is the boom member B3 (Bα).

[0061] The controller 25 controls the operation of the multi-stage boom 1, including the extension and contraction of the multi-stage boom 1, based on the determination result of whether or not the front section 3 is attached to the rear section 2. The controller 25 also controls the operation of the multi-stage boom 1 based on the determination result of which of the boom members (telescopic boom members) B2, B3, Bj is the frontmost section of the multi-stage boom 1, i.e., the determination result of the number of sections of the multi-stage boom 1. The weight and the length in the longitudinal direction of the multi-stage boom 1 vary depending on the attachment state (connected state) of the front section 3 to the rear section 2 and the number of sections of the multi-stage boom 1. For this reason, the controller 25 controls the operation of the multi-stage boom 1, including the extension and contraction of the multi-stage boom 1, in accordance with the real-time attachment state of the front section 3 to the rear section 2, etc. The operation of the multi-stage boom 1 is controlled based on the results of determining the attachment status of the front section 3 to the rear section 2 and the results of determining the number of sections of the multi-stage boom 1, as well as information indicating the history of extension and contraction of each of the telescopic boom members and operational commands related to the operation of the multi-stage boom 1.

[0062] As shown in Figure 5 and other figures, the controller 25 controls the extension and retraction of the telescopic cylinder 10, i.e., the operation of the telescopic cylinder 10, thereby controlling the extension and retraction of the multi-section boom 1. In controlling the operation of the telescopic cylinder 10, i.e., the extension and retraction of the multi-section boom 1, the controller 25 sets the extension and retraction range of the telescopic cylinder 10 in accordance with the determination results of the attachment state of the front section 3 to the rear section 2 and the determination results of the number of sections of the multi-section boom 1. The controller 25 then controls the operation of the telescopic cylinder 10 so that the telescopic cylinder 10 only extends and retracts within the set extension and retraction range. The set extension and retraction range of the telescopic cylinder 10 differs depending on the determination results of the attachment state of the front section 3 to the rear section 2 and the determination results of the number of sections of the multi-section boom 1. In other words, when it is determined that the front section 3 is attached to the rear section 2, the set extension and retraction range of the telescopic cylinder 10 is different from when it is determined that the front section 3 is separated from the rear section 2. When it is determined that the multi-stage boom 1 has four stages, the telescopic range of the telescopic cylinder 10 that is set is different from when it is determined that the multi-stage boom 1 has six stages.

[0063] When the front section 3 is attached to the rear section 2 and it is determined that the boom member B6 (Bγ) is the frontmost section of the multi-section boom 1 (the multi-section boom 1 has six sections), and the cylinder tube 12 (connecting member 16) is not connected to any of the boom members B2, B3, or Bj, the telescopic range of the telescopic cylinder 10, i.e., the range within which the connecting member 16 can move in the longitudinal direction of the multi-section boom 1, is set to the range between the position where the cylinder tube 12 can be connected to the boom member B2 and the position where the cylinder tube 12 can be connected to the boom member B6. For example, when the boom members (telescopic boom members) B2, B3, and Bj are each fully retracted (extension rate 0%) as shown in Figure 1(a), the range δa is set as the telescopic range of the telescopic cylinder 10 when the cylinder tube 12 is not connected to any of the boom members B2, B3, or Bj.

[0064] Furthermore, when the front section 3 is attached to the rear section 2 and it is determined that the boom member B4 (Bβ) is the frontmost section of the multi-section boom 1, and the cylinder tube 12 (connecting member 16) is not connected to any of the boom members B2, B3, or Bj, the telescopic range of the telescopic cylinder 10 (the range within which the connecting member 16 can move in the longitudinal direction of the multi-section boom 1) is set to the range between the position where the cylinder tube 12 can be connected to the boom member B2 and the position where the cylinder tube 12 can be connected to the boom member B4. For example, when the boom members (telescopic boom members) B2, B3, and Bj are all fully retracted as shown in Figure 1(a), the telescopic range of the telescopic cylinder 10 when the cylinder tube 12 is not connected to any of the boom members B2, B3, or Bj is set to range δb.

[0065] If it is determined that the front section 3 will be separated from the rear section 2, and the cylinder tube 12 (connecting member 16) is not connected to either boom member B2 or B3, the telescopic range of the telescopic cylinder 10 is set to the range between the position where the cylinder tube 12 can be connected to the boom member B2 and the position where the cylinder tube 12 can be connected to the boom member B3. For example, when the boom members (telescopic boom members) B2 and B3 are fully retracted as shown in Figure 1(b), the telescopic range of the telescopic cylinder 10 when the cylinder tube 12 is not connected to either boom member B2 or B3 is set to range δc.

[0066] As shown in FIG. 5 and other figures, the controller 25 that controls the operation of the multi-stage boom 1 controls the operation of the hoisting cylinder 7, thereby controlling the raising and lowering of the multi-stage boom 1. In controlling the operation of the multi-stage boom 1, including the extension and lowering of the multi-stage boom 1, the controller 25 calculates the real-time working radius of the multi-stage boom 1 and controls the extension and lowering of the multi-stage boom 1 so that the multi-stage boom 1 does not interfere with obstacles around the crane. The controller 25 also calculates the load (actual load) that is being applied to the multi-stage boom 1 in real time due to a lifted load, etc., and calculates and sets a limit value (upper limit value) for the load that can be applied to the multi-stage boom 1. The controller 25 then issues a warning or the like when the difference between the real-time load and the limit value falls below a threshold, and forcibly stops the operation of the multi-stage boom 1, including the extension and lowering of the multi-stage boom 1, when the real-time load exceeds the limit value.

[0067] Here, the real-time working radius of the multi-stage boom 1 is calculated based on the longitudinal length of the multi-stage boom 1, etc., and the load (actual load) acting on the multi-stage boom 1 in real time and the limit value of the load acting on the multi-stage boom 1 are calculated based on the longitudinal length of the multi-stage boom 1 and the weight of the multi-stage boom 1, etc. For this reason, the calculated real-time working radius and load (actual load) of the multi-stage boom 1 and the set limit value for the load of the multi-stage boom 1 differ depending on the determination result for the attachment state of the front section 3 to the rear section 2 and the determination result for the number of sections of the multi-stage boom 1. In other words, when it is determined that the front section 3 is attached to the rear section 2, the calculation results for the real-time working radius and load of the multi-stage boom 1 and the set limit value for the load of the multi-stage boom 1 will differ from when it is determined that the front section 3 is separated from the rear section 2. Furthermore, when it is determined that the multi-stage boom 1 has four stages, the calculation results for the real-time working radius and load of the multi-stage boom 1, and the limit values ​​set for the load of the multi-stage boom 1, will be different from when it is determined that the multi-stage boom 1 has six stages.

[0068] In this embodiment, the processes shown in Figures 6 and 7 are performed to determine the attachment state of the front section 3 to the rear section 2. Therefore, in the operation of separating the front section 3 from the rear section 2, the controller 25 performs the following determination and process. That is, in the state shown in Figure 4(a), when the connector 23 (extended end) of the cord 22 is connected to the front section 3 (the connector 23 is connected to the position shown by the solid line), the controller 25 determines S101-Yes. Then, in S102, the controller 25 determines that the front section 3 is attached to the rear section 2, and determines that boom member B6 (Bγ) is the foremost section of the multi-section boom 1.

[0069] Then, when the connection destination of the connector 23 (extended end) of the cord 22 is changed to the rear section 2 (position indicated by the dashed line) in the state of FIG. 4(a), the controller 25 makes determinations in the following order: No in S101, Yes in S103, Yes in S104, and Yes in S105. Then, the controller 25 determines in S106 that the front section 3 is attached to the rear section 2, and determines in S107 that the boom member B4 (Bβ) is the frontmost section of the multi-section boom 1. After the boom member B4 is extended to the state of FIG. 4(b), until the connection of the cylinder tube 12 to the boom member B4 is released, the controller 25 makes determinations in the following order: No in S101, Yes in S103, Yes in S104, and Yes in S105, and makes determinations regarding the attachment state of the front section 3 to the rear section 2 as shown in S106 and S107.

[0070] Then, when the connection of the cylinder tube 12 to the boom member B4 (Bβ) is released, the controller 25 makes determinations in the order of No in S101, Yes in S103, and No in S104 until the cylinder tube 12 is connected to the boom member B3 (Bα) in the state of FIG. 4(c). For this reason, the controller 25 does not make a determination about the attachment state between the front section 3 and the rear section 2. Therefore, until the cylinder tube 12 is connected to the boom member B3 (Bα) in the state of FIG. 4(c), the determination results that the front section 3 is attached to the rear section 2 and that the boom member B4 (Bβ) is the frontmost section of the multi-section boom 1 are maintained.

[0071] When the cylinder tube 12 is connected to the boom member B3 (Bα) in the state shown in FIG. 4(c), the controller 25 makes a determination in the following order: No in S101, Yes in S103, Yes in S104, No in S105, and Yes in S108. Since the multi-stage boom 1 is in a predetermined boom hoisting state in the state shown in FIG. 4(c), the controller 25 makes a determination in S111: Yes. Furthermore, since only the boom member B4 (Bβ) is in its most extended state in the state shown in FIG. 4(c), and each of the telescopic boom members other than boom member B4 is in its most retracted state, the first reference condition is satisfied for the telescopic states of the boom members B2, B3, and Bj. Therefore, the controller 25 makes a determination in the following order: No in S112, Yes in S113. Furthermore, since the pressure in the boom hoisting cylinder 7 is within the first pressure range in the state shown in FIG. 4(c), the controller 25 makes a determination in S114: Yes. Then, the controller 25 determines in S106 that the front section 3 is attached to the rear section 2, and determines in S107 that the boom member B4 (Bβ) is the frontmost section of the multi-section boom 1.

[0072] While the state of the multi-stage boom 1 is being changed in the order of FIGS. 4(d), 4(e), and 4(f), the boom member B3 (Bα) is in an extended state from its most retracted state, and the extension rate of the boom member B3 is not 0%. Therefore, neither the first nor the second reference condition is satisfied with respect to the extension and contraction states of the boom members B2, B3, and Bj. Therefore, while the state of the multi-stage boom 1 is being changed in the order of FIGS. 4(d), 4(e), and 4(f), the controller 25 makes determinations in the order of S101 - No, S103 - Yes, S104 - Yes, S105 - No, S108 - Yes, S111 - Yes, S112 - No, and S113 - No. Therefore, the controller 25 does not determine the attachment state between the front section 3 and the rear section 2. Furthermore, when the front section 3 is separated from the rear section 2 in the state shown in Figure 4(f), the controller 25 determines that the boom member B4 (Bβ) is in the most extended state and that the boom members B5 and B6 are in the most retracted state. Until the controller 25 determines that the front section 3 is in the separated state from the rear section 2, these determinations regarding the extension / contraction states of the boom members B4 to B6 are maintained even after the front section 3 is separated from the rear section 2 in the state shown in Figure 4(f).

[0073] Then, after the front section 3 is separated in the state shown in FIG. 4(f), in the state shown in FIG. 4(g), boom member B3 (Bα) is in the most contracted state (extension rate 0%). Therefore, in the state shown in FIG. 4(g), only boom member B4 (Bβ) is in the most extended state, and it is determined that each of the telescopic boom members other than boom member B4 is in the most contracted state, and the first reference condition is satisfied for the telescopic states of boom members B2, B3, and Bj. Therefore, the controller 25 makes determinations in the following order: No in S101, Yes in S103, Yes in S104, No in S105, Yes in S108, Yes in S111, Yes in S112, No, and Yes in S113. Furthermore, in the state shown in FIG. 4(g), the pressure in the boom hoisting cylinder 7 falls within the second pressure range, so the controller 25 makes determinations in the following order: No in S114, Yes in S115. Then, in S109, the controller 25 determines that the front section 3 is separated from the rear section 2, and determines that the boom member B3 (Bα) is the frontmost section of the multi-section boom 1.

[0074] When attaching the front section 3 to the rear section 2, the controller 25 performs the following determinations and processes. Specifically, in the state shown in FIG. 4(g), the boom members B2 and B3 of the rear section 2 are each fully retracted, and no information about the boom member Bj of the front section 3 is input to the controller 25. Therefore, in the state shown in FIG. 4(g), it is determined that all of the telescopic boom members are fully retracted, and the telescopic states of the boom members B2, B3, and Bj satisfy the second reference condition. Therefore, the controller 25 makes determinations in the following order: No in S101, Yes in S103, Yes in S104, No in S105, Yes in S108, Yes in S111, and Yes in S112. Furthermore, in the state shown in FIG. 4(g), the pressure in the boom hoisting cylinder 7 falls within the second pressure range, so the controller 25 makes determinations in the following order: No in S114, Yes in S115. Then, in S109, the controller 25 determines that the front section 3 is separated from the rear section 2, and determines that the boom member B3 (Bα) is the frontmost section of the multi-section boom 1.

[0075] While the state of the multi-stage boom 1 is being changed in the order of FIGS. 4(f), 4(e), and 4(d), the boom member B3 (Bα) is in an extended state from its most retracted state, and the extension rate of the boom member B3 is not 0%. Therefore, neither the first nor the second reference condition is satisfied with respect to the extension and contraction states of the boom members B2, B3, and Bj. Therefore, while the state of the multi-stage boom 1 is being changed in the order of FIGS. 4(f), 4(e), and 4(d), the controller 25 makes determinations in the order of S101 - No, S103 - Yes, S104 - Yes, S105 - No, S108 - Yes, S111 - Yes, S112 - No, and S113 - No. Therefore, the controller 25 does not make a determination regarding the attachment state between the front section 3 and the rear section 2. Furthermore, even after the front section 3 is attached to the rear section 2 in the state shown in Figure 4(d), information relating to the extension and contraction states of the boom members Bj (B4 to B6) is not input to the controller 25 until the controller 25 determines that the front section 3 is attached to the rear section 2. Even if the controller 25 determines that the front section 3 is attached to the rear section 2, information relating to the extension and contraction states of the boom members B5 and B6, i.e., the telescopic boom members in the front section 3 other than boom member B4, is not input to the controller 25 while it is determined that the boom member B4 (Bβ) is the foremost section in the multi-section boom 1.

[0076] After the front section 3 is attached in the state shown in FIG. 4(d), in the state shown in FIG. 4(c), the boom member B3 (Bα) is in the most contracted state (extension rate 0%). Furthermore, during the transition from the state shown in FIG. 4(d) to the state shown in FIG. 4(c), the controller 25 does not determine that the front section 3 is attached to the rear section 2, and information regarding the extension and contraction states of the boom members Bj (B4-B6) is not input to the controller 25. Therefore, when the multi-stage boom 1 changes from the state shown in FIG. 4(d) to the state shown in FIG. 4(c), it is determined that each of the telescopic boom members is in the most contracted state, and the second reference condition is satisfied regarding the extension and contraction states of the boom members B2, B3, and Bj. Therefore, the controller 25 makes determinations in the following order: No in S101, Yes in S103, Yes in S104, No in S105, Yes in S108, Yes in S111, and Yes in S112. 4(c), the pressure in the boom hoisting cylinder 7 is within the first pressure range, so the controller 25 determines S114-Yes. Then, in S106, the controller 25 determines that the front section 3 is attached to the rear section 2, and in S107, determines that boom member B4 (Bβ) is the frontmost section of the multi-section boom 1.

[0077] Then, after the connection of the cylinder tube 12 to the boom member B3 (Bα) is released, while the telescopic cylinder 10 is extended to the state shown in FIG. 4(b), the controller 25 makes determinations in the following order: No in S101, Yes in S103, and No in S104. Therefore, the determination results that the front section 3 is attached to the rear section 2 and that the boom member B4 (Bβ) is the frontmost section of the multi-section boom 1 are maintained. Then, when the cylinder tube 12 is connected to the boom member B4 (Bβ) in the state shown in FIG. 4(b), the controller 25 makes determinations in the following order: No in S101, Yes in S103, Yes in S104, and Yes in S105, and makes determinations regarding the attachment state of the front section 3 to the rear section 2 as shown in S106 and S107. Then, in the state of Figure 4(a), when the connection destination of the connector 23 (extended end) of the cord 22 is changed to the front part 3 (position shown by the solid line), the controller 25 judges S101-Yes and judges the attachment state of the front part 3 to the rear part 2 as shown in S102.

[0078] In this embodiment, when the extended end of the cord 22 is connected to the rear section 2 and the telescopic cylinder 10 is connected to the frontmost boom member Bα (B3) in the rear section 2, the controller 25 determines whether the front section is attached to the rear section based on the pressure of the hoisting cylinder 7 when the multi-section boom 1 is in a predetermined hoisting state and the telescopic states of the multiple boom members (telescopic boom members) B2, B3, Bj satisfy the aforementioned reference condition (first reference condition or second reference condition). Therefore, even if the connection destination of the extended end of the cord 22 is changed when the multi-section boom 1 is in the most retracted state, such as the state shown in Figure 4(a), it is possible to appropriately determine whether the front section 3 is attached to the rear section 2 during both the attachment and detachment of the front section 3 to and from the rear section 2.

[0079] Furthermore, in this embodiment, with the extended end of the cord 22 connected to the rear section 2 and the telescopic cylinder 10 connected to the boom member Bα (B3), only when the multi-section boom 1 is in a predetermined boom hoisting state and the telescopic state of the multiple boom members B2, B3, Bj satisfies the first or second reference condition, the controller 25 determines whether the front section 3 is attached to the rear section 2 based on the pressure in the hoisting cylinder 7. If the pressure in the hoisting cylinder 7 is within the aforementioned first pressure range, the controller 25 determines that the front section 3 is attached to the rear section 2, and if the pressure in the hoisting cylinder 7 is within the aforementioned second pressure range, the controller 25 determines that the front section 3 is separated from the rear section 2. Then, based on the fact that the rearmost boom member B4 (Bβ) in the front section 3 is in the most extended state and that the telescopic boom members other than boom member B4 are each in the most retracted state, it is determined that the first reference condition is satisfied with respect to the telescopic states of the multiple boom members B2, B3, Bj. Also, based on the fact that all of the telescopic boom members are each in the most retracted state, it is determined that the second reference condition is satisfied with respect to the telescopic states of the multiple boom members B2, B3, Bj.

[0080] By performing this determination process, even if the connection destination of the extended end of the cord 22 is changed when the multi-stage boom is at its most retracted state in Figure 4(a) and then the state of the multi-stage boom 1 is changed in the order of Figures 4(a), 4(b), ..., 4(f), and 4(g) to perform an operation to separate the front section 3 from the rear section 2, it is possible to more appropriately determine whether the front section 3 is attached to the rear section 2. Similarly, even if the connection destination of the extended end of the cord 22 is changed when the multi-stage boom is at its most retracted state in Figure 4(a) and then the state of the multi-stage boom 1 is changed in the order of Figures 4(g), 4(f), ..., 4(b), and 4(a), it is possible to more appropriately determine whether the front section 3 is attached to the rear section 2.

[0081] In this embodiment, the controller 25 controls the operation of the multi-stage boom 1, including the extension and contraction of the multi-stage boom 1, based on the determination result regarding the attachment state of the front section 3 to the rear section 2. In this embodiment, the attachment state of the front section 3 to the rear section 2 is appropriately determined, as described above. Therefore, by controlling the operation of the multi-stage boom 1 based on the appropriately determined determination result, the operation of the multi-stage boom 1 is appropriately and safely controlled in accordance with whether or not the front section 3 is attached to the rear section 2.

[0082] Furthermore, in this embodiment, if it is determined that the front section 3 is attached to the rear section when the extended end of the cord 22 is connected to the rear section 2, the controller 25 determines that the rearmost boom member Bβ (B4) in the front section 3 is the frontmost section of the multi-section boom 1, and controls the operation of the multi-section boom 1. In other words, the controller 25 determines that the multi-section boom 1 is in the β-stage (four stages in this embodiment), and controls the operation of the multi-section boom 1. As a result, even if it is impossible to determine the number of telescopic boom members in the front section 3, i.e., even if it is impossible to determine the number of stages of the multi-section boom 1 when the front section 3 is attached to the rear section 2, the operation of the multi-section boom 1 is controlled appropriately and safely.

[0083] For example, the controller 25 sets the telescopic range of the telescopic cylinder 10 based on the results of determining the attachment state of the front section 3 to the rear section 2 and the number of sections of the multi-section boom 1. As a result, the telescopic range of the telescopic cylinder 10 is appropriately set to a range that corresponds to the real-time attachment state of the front section 3 to the rear section 2 and the number of sections of the multi-section boom 1. As a result, the operation of the telescopic cylinder 10 is controlled so that the telescopic cylinder 10 extends and retracts within the set telescopic range, thereby appropriately controlling the operation of the telescopic cylinder 10 and appropriately controlling the extension and retraction of the multi-section boom 1. By appropriately controlling the operation of the telescopic cylinder 10 and the extension and retraction of the multi-section boom 1, the telescopic cylinder 10 is effectively prevented from being overextended beyond the appropriate telescopic range. This effectively prevents the cylinder tube 12 from coming out of the cylinder guide and the front end of the cylinder tube 12 from interfering with the boom head 5.

[0084] Furthermore, the controller 25 acquires the length of the multi-stage boom 1 in the longitudinal direction and the weight of the multi-stage boom 1 based on the determination results of the attachment state of the front section 3 to the rear section 2 and the determination results of the number of sections of the multi-stage boom 1, and calculates the real-time working radius of the multi-stage boom 1, the load (actual load) acting on the multi-stage boom 1 in real time, and the limit value (upper limit value) for the load acting on the multi-stage boom 1. Therefore, values ​​corresponding to the determination results of the real-time attachment state of the front section 3 to the rear section 2 and the number of sections of the multi-stage boom 1 are appropriately calculated as the working radius of the multi-stage boom 1, the load (actual load) of the multi-stage boom 1, and the limit value for the load of the multi-stage boom 1. Therefore, by controlling the extension and contraction, elevation and the like of the multi-stage boom 1 based on the calculated working radius of the multi-stage boom 1, interference of the multi-stage boom 1 with obstacles around the crane is effectively prevented. Furthermore, by controlling the operation of the multi-stage boom 1 based on the calculated load of the multi-stage boom 1 and the limit value for the load of the multi-stage boom 1, an appropriate warning is issued in response to the real-time attachment state of the front section 3 to the rear section 2, and the operation of the multi-stage boom 1 is appropriately forcibly stopped. This effectively prevents the crane from assuming a position that makes it more likely to tip over.

[0085] Furthermore, in this embodiment, in both the operation of attaching the front section 3 to the rear section 2 and the operation of separating the front section 3 from the rear section 2, the connection destination of the extended end of the cord 22 can be changed when the multi-stage boom 1 is in its most retracted state. This simplifies the operation of changing the connection destination of the extended end of the cord 22. Furthermore, because the connection destination of the extended end of the cord 22 can be changed when the multi-stage boom 1 is in its most retracted state, work efficiency and safety are improved in the operation of changing the connection destination of the extended end of the cord 22.

[0086] (Variation) In the first modified example, the processes shown in FIGS. 6 and 8 are performed to determine the attachment state of the front section 3 to the rear section 2. In this modified example, the controller 25 performs the processes of S101 to S110 shown in FIG. 6 in the same manner as in the previously described embodiment. In this modified example, the controller 25 also performs the processes of S111 to S115 in the same manner as in the previously described embodiment. However, in this modified example, if the second reference condition is satisfied in S112 with respect to the real-time extension / retraction state of the boom members B2, B3, and Bj (Yes in S112), the controller 25 determines whether the real-time pressure of the boom hoisting cylinder 7 is within a third pressure range (S116). The third pressure range is outside the first and second pressure ranges and includes a pressure value (third pressure value) P3 between the aforementioned pressure values ​​P1 and P2. Therefore, the pressure values ​​P1 and P2 are not included in the third pressure range. In one example, using the above-mentioned value ΔP, a pressure range equal to or greater than the pressure value P3−ΔP and equal to or less than the pressure value P3+ΔP is set as the third pressure range.

[0087] If the pressure in the hoisting cylinder 7 is within the third pressure range (S116-Yes), the controller 25 determines that the front section 3 is attached to the rear section 2 (S106) and that boom member B4 (Bβ) is the frontmost section of the multi-stage boom 1 (S107). On the other hand, if the pressure in the hoisting cylinder 7 is not within the third pressure range (S116-No), the controller 25 determines whether the real-time pressure in the hoisting cylinder 7 is within the first pressure range (S114). In this modified example, the attachment state of the front section 3 to the rear section 2 is determined in the same manner as in the previously described embodiment during the attachment and detachment of the front section 3 from the rear section 2. Therefore, this modified example also provides the same functions and effects as the previously described embodiment.

[0088] Here, when separating the front section 3 from the rear section 2, as described above, the connection destination of the connector 23 (extension end) of the cord 22 is changed from the front section 3 to the rear section 2 while the telescopic cylinder 10 is connected to the boom member B4 (Bβ). However, when separating the front section 3 from the rear section 2, as shown in Figure 9 and other figures, there is a possibility that the connection destination of the connector 23 (extension end) of the cord 22 will be mistakenly changed from the front section 3 to the rear section 2 while the telescopic cylinder 10 is connected to the boom member B3 (Bα). In Figure 9, the front section 3 is attached to the rear section 2, and each of the boom members (telescopic boom members) B2, B3, and Bj is in its most retracted state.

[0089] In this modified example, the attachment state of the front section 3 to the rear section 2 is determined using the processes shown in FIGS. 6 and 8. Therefore, even if the connection destination of the connector 23 of the cord 22 is changed from the front section 3 (position indicated by the solid line) to the rear section 2 (position indicated by the dashed line) in the state shown in FIG. 9, the controller 25 makes determinations in the following order: No in S101, Yes in S103, Yes in S104, No in S105, Yes in S108, Yes in S111, and Yes in S112. Then, in the state shown in FIG. 9, the pressure in the boom hoisting cylinder 7 falls within the third pressure range, so the controller 25 makes a determination of Yes in S116. Then, the controller 25 determines in S106 that the front section 3 is attached to the rear section 2, and determines in S107 that boom member B4 (Bβ) is the foremost section of the multi-section boom 1.

[0090] As described above, in this modified example, even if the connection destination of the connector 23 (extended end) of the cord 22 is mistakenly changed from the front section 3 to the rear section 2 while the telescopic cylinder 10 is connected to the boom member B4 (Bβ), the front section 3 is determined to be attached to the rear section 2. Therefore, after the connection destination of the connector 23 of the cord 22 is mistakenly changed from the front section 3 to the rear section 2, there is no need to return the connection destination of the connector 23 of the cord 22 to the front section 3. Therefore, in this modified example, the degree of freedom and efficiency of the work are improved when, for example, separating the front section 3 from the rear section 2.

[0091] Furthermore, in the above-described embodiments, the rear section 2 is formed from one base boom member (B1) and two telescopic boom members (B2, B3), but the rear section 2 may comprise one base boom member and one or more telescopic boom members. Furthermore, in the above-described embodiments, the front section 3 is formed from three telescopic boom members (B4 to B6), but the front section 3 may comprise one or more telescopic boom members. In these cases, the attachment state (connection state) between the front section 3 and the rear section 2 is determined in the same manner as in the above-described embodiments. Therefore, the same functions and effects as in the above-described embodiments are achieved.

[0092] Furthermore, any one of two or more types of front sections may be selectively attachable to the rear section 2. In this case, whether or not a front section is attached to the rear section 2 is determined in each of the operations of attaching any one of the types of front sections to the rear section 2 and separating the front section attached to the rear section 2 from the rear section 2, in the same manner as in the above-described embodiment. Therefore, the same functions and effects as in the above-described embodiment are achieved. Note that when any one of two or more types of front sections is selectively attachable to the rear section 2, the two or more types of front sections may differ from one another in one or more of the number of boom members (telescopic boom members), longitudinal length, weight, etc. In other words, the two or more types of front sections may be the same in the number of boom members (telescopic boom members) provided as long as they differ from one another in one or more of the longitudinal length, weight, etc.

[0093] In a configuration in which one of two or more types of front sections can be selectively attached to the rear section 2, it may be determined which of the two or more types of front sections is attached to the rear section 2 based on the pressure of the hoisting cylinder 7. In this modified example, with the extended end of the cord 22 connected to the rear section 2 and the telescopic cylinder 10 connected to the frontmost boom member Bα in the rear section 2, it is determined whether any of the front sections is attached to the rear section 2 and the type of front section attached to the rear section 2 based on the pressure of the hoisting cylinder 7 only when the multi-section boom 1 is in a predetermined hoisting state and the extension and contraction states of the multiple telescopic boom members comprising the multi-section boom 1 satisfy the first or second reference condition.

[0094] In this modified example, when determining the type of front portion attached to the rear portion 2, for example, based on the pressure of the hoisting cylinder 7 being within the first pressure range greater than or equal to pressure value P1-ΔP and less than or equal to pressure value P1+ΔP, it is determined that a first front portion, which is one of two or more types of front portions, is attached to the rear portion 2. In addition, a pressure value P4 greater than pressure value P1 is defined, and a fourth pressure range is defined that is outside the first pressure range and includes pressure value P4. Then, when determining the type of front portion attached to the rear portion 2, for example, based on the pressure of the hoisting cylinder 7 being within the fourth pressure range greater than or equal to pressure value P4-ΔP and less than or equal to pressure value P4+ΔP, it is determined that a second front portion, which is a different type from the first front portion of the two or more types of front portions, is attached to the rear portion 2. In this case, the second front side section has a larger number of boom members (telescopic boom members), is longer in length in the longitudinal direction, or is heavier than the first front side section.

[0095] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in combination as appropriate as possible, and in such cases, the combined effects can be obtained. Furthermore, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining the disclosed multiple constituent elements. [Explanation of symbols]

[0096] 1...multi-stage boom, 2...rear portion, 3...front portion, 7...raisal cylinder, 10...telescopic cylinder, 12...cylinder tube, 17...pressure gauge, 18...detector, 20...boom control device, 22...cord, 23...connector, 25...controller, Bi, Bj...boom member, Dk...detection plate

Claims

1. A boom control device for controlling the operation of a multi-stage boom, comprising: a rearmost base boom member; and a plurality of telescopic boom members that are extendable and retractable in the longitudinal direction relative to the base boom member; and a front section formed of one or more of the telescopic boom members detachably attached to a rear section formed of the base boom member and one or more of the telescopic boom members, a cord extending from the rear portion and having an extended end connectable to the front portion; a telescopic cylinder selectively connectable to one of the telescopic boom members and extending or retracting the connected telescopic boom member by telescoping; a boom-raising cylinder that is extended or retracted to raise or lower the multi-stage boom; a controller that determines whether the front section is attached to the rear section based on the pressure of the hoisting cylinder when the extended end of the cord is connected to the rear section and the telescopic cylinder is connected to a first telescopic boom member that is the frontmost telescopic boom member in the rear section, and when the multi-section boom is in a predetermined hoisting state and standard conditions are met for the extension and contraction states of the plurality of telescopic boom members; and controls the operation of the multi-section boom, including extension and contraction of the multi-section boom, based on the determination result of whether the front section is attached to the rear section. A boom control device comprising:

2. When the extended end of the cord is connected to the rear section and the telescopic cylinder is connected to the first telescopic boom member, the controller determines whether the front section is attached to the rear section based on the pressure of the hoisting cylinder when the multi-stage boom is in the predetermined hoisting state and the telescopic state of the plurality of telescopic boom members satisfies a first reference condition or a second reference condition different from the first reference condition, When the extended end of the cord is connected to the rear section and the telescopic cylinder is connected to the first telescopic boom member, the controller: when the multi-stage boom is in the predetermined hoisting state and the first reference condition or the second reference condition is satisfied with respect to the extension and contraction states of the plurality of telescopic boom members, it is determined that the front section is attached to the rear section based on the pressure of the hoisting cylinder being within a first pressure range that includes a first pressure value and does not include a second pressure value that is smaller than the first pressure value; When the multi-stage boom is in the predetermined hoisting state and the first reference condition or the second reference condition is satisfied with respect to the extension and contraction states of the plurality of telescopic boom members, it is determined that the front section is separated from the rear section based on the pressure in the hoisting cylinder being outside the first pressure range and within a second pressure range that includes the second pressure value. The boom control device of claim 1.

3. 3. The boom control device according to claim 1 or 2, wherein the controller determines that the front section is attached to the rear section based on whether the telescopic cylinder is connected to any one of the telescopic boom members of the front section when the extended end of the cord is connected to the rear section.

4. The boom control device according to claim 1 , wherein the controller determines that the front portion is attached to the rear portion based on the fact that the extended end of the cord is connected to the front portion.

5. a detector that moves along the longitudinal direction by the extension and retraction operation of the telescopic cylinder and detects a detection target provided on each of the telescopic boom members by proximity; When the detector detects the detection object on any one of the telescopic boom members, the telescopic cylinder is connected to the telescopic boom member that the detector detects the detection object, or is located at a position in the longitudinal direction where the detection object can be connected to the telescopic boom member that the detector detects the detection object. The boom control device according to any one of claims 1 to 4.

6. 6. The boom control device according to claim 1, wherein, when the controller determines that the front portion is attached to the rear portion with the extended end of the cord connected to the rear portion, the controller determines that the second telescopic boom member, which is the rearmost telescopic boom member in the front portion, is the frontmost section of the multi-stage boom, and controls the operation of the multi-stage boom, including the extension and contraction of the multi-stage boom.

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