Working machine

Abstract

To provide a working machine capable of holding a state where connection between a boom and an actuator by a first pin is released and a state where connection between adjacent booms by a second pin is released.SOLUTION: The working machine includes a telescopic boom having a plurality of booms and configured to be extended and retracted by an extension device, a first pin configured to connect the boom and the extension device, and a second pin configured to connect adjacent booms. A moving mechanism for releasing connection between members connected by one pin, a brake mechanism for braking a motor, and a control unit for controlling the moving mechanism are provided, and the control unit turns on the brake mechanism after a first predetermined time elapses after the one pin reaches a preset first position when the one pin moves.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a work machine equipped with a telescopic boom. [Background technology]

[0002] Patent Document 1 discloses a mobile crane equipped with a telescopic boom in which multiple booms are nested one on top of the other and a hydraulic telescopic device that extends the telescopic boom.

[0003] Adjacent booms are connected to each other by a boom connecting pin (in other words, a second pin). A boom that is released from the connection by the boom connecting pin (hereinafter referred to as a movable boom) becomes movable in the extension / retraction direction relative to the other booms.

[0004] The telescopic device is connected to the movable boom via a cylinder connecting pin (in other words, the first pin). When the telescopic device moves in the telescopic direction, the movable boom moves together with the actuator, and the telescopic boom extends or retracts. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-96928 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, the above-described crane includes a boom connecting mechanism that displaces the boom connecting pin, and a cylinder connecting mechanism that displaces the cylinder connecting pin.

[0007] In recent years, cranes have been developed that include boom connection mechanisms and cylinder connection mechanisms that operate based on the power of an electric motor. These cranes require a mechanism that maintains the state in which the boom and telescopic device are disconnected by the cylinder connection pin (i.e., the first pin), and the state in which adjacent booms are disconnected by the boom connection pin (i.e., the second pin).

[0008] An object of the present invention is to provide a work machine that can maintain a state in which the connection between the boom and the actuator by the first pin is released, and a state in which the connection between adjacent booms by the second pin is released. [Means for solving the problem]

[0009] One aspect of the working machine according to the present invention is a telescopic boom having a plurality of booms and extending and retracting by a telescopic device; a first pin that connects the boom and the telescopic device; a second pin connecting adjacent booms; a movement mechanism that moves one of the first pin and the second pin in a removal direction using a motor to release the connection between the members connected by the one pin; a brake mechanism for braking the motor; a control unit that controls the movement mechanism, When one of the pins moves, the control unit turns the brake mechanism on after a first predetermined time has elapsed since the one of the pins reaches a preset first position. [Effects of the Invention]

[0010] According to the present invention, a work machine can be provided that can maintain a state in which the connection between the boom and the actuator by the first pin is released, and a state in which the connection between adjacent booms by the second pin is released. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a mobile crane according to an embodiment of the present invention. [Figure 2A] FIG. 2A is a schematic diagram for explaining the structure and extension / retraction operation of a telescopic boom. [Figure 2B] FIG. 2B is a schematic diagram for explaining the structure and extension / retraction operation of the telescopic boom. [Figure 2C] FIG. 2C is a schematic diagram for explaining the structure and extension / retraction operation of the telescopic boom. [Figure 2D] FIG. 2D is a schematic diagram for explaining the structure and extension / retraction operation of the telescopic boom. [Figure 2E] FIG. 2E is a schematic diagram for explaining the structure and extension / retraction operation of the telescopic boom. [Figure 3A] FIG. 3A is a schematic diagram for explaining the operation of the cylinder coupling mechanism. [Figure 3B] FIG. 3B is a schematic diagram for explaining the operation of the cylinder coupling mechanism. [Figure 3C] FIG. 3C is a schematic diagram for explaining the operation of the cylinder coupling mechanism. [Figure 4A] FIG. 4A is a schematic diagram for explaining the operation of the boom connecting mechanism. [Figure 4B] FIG. 4B is a schematic diagram for explaining the operation of the boom connection mechanism. [Figure 4C] FIG. 4C is a schematic diagram for explaining the operation of the boom connection mechanism. [Figure 5A] FIG. 5A is a diagram showing a detection area of ​​a position information detection device. [Figure 5B] FIG. 5B is a schematic diagram showing the positional relationship between the detection area of ​​the position information detection device and the cylinder connecting pin. [Figure 5C] FIG. 5C is a schematic diagram showing the positional relationship between the detection area of ​​the position information detecting device and the boom connecting pin. [Figure 6] FIG. 6 is an enlarged schematic view of the cylinder connecting pin and the cylinder pin receiving portion. [Figure 7] FIG. 7 is an enlarged schematic view of the boom connecting pin and the boom pin receiving portion. [Figure 8] FIG. 8 is a flowchart showing the brake control process. DETAILED DESCRIPTION OF THE INVENTION

[0012] An example of an embodiment of the present invention will be described in detail below with reference to the drawings. Note that the crane according to the embodiment described below is an example of a work machine according to the present invention, and the present invention is not limited to the embodiment described below.

[0013] [Embodiment] A mobile crane 1 according to an embodiment of the present invention will be described with reference to Figures 1 to 8. First, an overview of the mobile crane 1 according to an embodiment of the present invention will be described with reference to Figures 1 and 2A to 2E.

[0014] Examples of mobile cranes include rough terrain cranes, all-terrain cranes, truck cranes, and loaded truck cranes. However, the work machine is not limited to a mobile crane and may be another work machine (e.g., an aerial work platform) equipped with a telescopic boom.

[0015] The mobile crane 1 has a telescopic boom 14 and an actuator 2. The telescopic boom 14 has multiple booms combined so that they can be extended and retracted. Adjacent booms are connected to each other by boom connecting pins (boom connecting pins 144a, 144b).

[0016] When extending or retracting the telescopic boom 14, the actuator 2 moves the boom in the extension / retraction direction. At this time, the actuator 2 connects to the boom to be moved via the cylinder connecting pins 454A, 454B, and releases the connection between the boom to be moved and the boom adjacent to the boom to be moved.

[0017] As shown in FIGS. 1 and 2A to 2E, the mobile crane 1 includes a traveling body 10, a swivel base 12, a telescopic boom 14, an actuator 2, a wire rope 16, and a hook 17.

[0018] The swivel base 12 is rotatably provided on the upper part of the traveling body 10. The telescopic boom 14 has multiple booms (for example, a tip boom 141, an intermediate boom 142, and a base boom 143, which will be described later) and is extended and retracted by the telescopic cylinder 3.

[0019] The base end of the telescopic boom 14 is fixed to the swivel base 12 and is capable of raising and lowering. The actuator 2 extends and retracts the telescopic boom 14. A wire rope 16 is supported by the telescopic boom 14 and hangs down from the tip of the telescopic boom 14. A hook 17 is attached to the tip of the wire rope 16.

[0020] Next, the telescopic boom 14 will be described with reference to Figures 1 and 2A to 2E. The telescopic boom 14 has multiple booms combined in a telescopic manner. Specifically, the multiple booms are, in order from the inside, a tip boom 141, an intermediate boom 142, and a base boom 143.

[0021] The telescopic boom 14 extends in order from the innermost boom, thereby transitioning from the contracted state shown in Fig. 2A to the extended state shown in Fig. 1. Note that there may be multiple intermediate booms.

[0022] The tip boom 141 is cylindrical and has an internal space capable of accommodating the actuator 2. The tip boom 141 has, at its base end, a pair of cylinder pin receiving portions 1411, 1412 and a pair of boom pin receiving portions 141b. The pair of cylinder pin receiving portions 1411, 1412 and the pair of boom pin receiving portions 141b are each a through hole.

[0023] The pair of cylinder pin receivers 1411, 1412 are coaxially provided at the base end of the tip boom 141. The pair of cylinder pin receivers 1411, 1412 are respectively engageable with and disengageable from a pair of cylinder connecting pins 454A, 454B provided on the cylinder member 32 of the telescopic cylinder 3.

[0024] The cylinder connecting pins 454A, 454B are each an example of a first pin, and are biased outward (in the direction from the base end toward the tip end of the cylinder connecting pins 454A, 454B) by a first biasing mechanism 455 (described later). The cylinder connecting pins 454A, 454B move inward (in the direction from the tip end toward the base end of the cylinder connecting pins 454A, 454B) based on the operation of a cylinder connecting mechanism 45 (described later).

[0025] With the cylinder connecting pins 454A, 454B engaged with the pair of cylinder pin receiving portions 1411, 1412, the tip boom 141 can move together with the cylinder member 32 in the extension / contraction direction.

[0026] The pair of boom pin receiving portions 141b are provided coaxially around the cylinder pin receiving portions 1411, 1412. The boom pin receiving portions 141b are respectively engageable with and disengageable from the pair of boom connecting pins 144a. For ease of explanation, in the drawings, the pair of boom pin receiving portions 141b and the pair of cylinder pin receiving portions 1411, 1412 are shown misaligned in the axial direction of the telescopic boom 14.

[0027] In reality, the pair of boom pin receiving portions 141b and the pair of cylinder pin receiving portions 1411, 1412 are aligned in the axial direction of the telescopic boom 14, and are provided at offset positions in the circumferential direction of the telescopic boom 14.

[0028] Each of the pair of boom connecting pins 144a corresponds to an example of a second pin, and is biased outward (in the direction from the base end toward the tip end of the boom connecting pin 144a) by a second biasing mechanism 463 described below. Each of the pair of boom connecting pins 144a connects the tip boom 141 and the intermediate boom 142. The pair of boom connecting pins 144a move inward (in the direction from the tip end toward the base end of the boom connecting pin 144a) based on the operation of a boom connecting mechanism 46 described below.

[0029] With the tip boom 141 and the intermediate boom 142 connected by a pair of boom connecting pins 144a, the boom connecting pin 144a is inserted so as to span between the boom pin receiving portion 141b of the tip boom 141 and the first boom pin receiving portion 142b or the second boom pin receiving portion 142c of the intermediate boom 142.

[0030] When the tip boom 141 and the intermediate boom 142 are connected, the tip boom 141 is prohibited from moving relative to the intermediate boom 142. On the other hand, when the tip boom 141 and the intermediate boom 142 are not connected, the tip boom 141 is movable relative to the intermediate boom 142.

[0031] The intermediate boom 142 is cylindrical and has an internal space capable of accommodating the tip boom 141. The intermediate boom 142 has a pair of cylinder pin receiving portions 142a, a pair of first boom pin receiving portions 142b, and a pair of third boom pin receiving portions 142d at its base end, and a pair of second boom pin receiving portions 142c at its tip end. The pair of cylinder pin receiving portions 142a, the pair of first boom pin receiving portions 142b, the pair of third boom pin receiving portions 142d, and the pair of second boom pin receiving portions 142c are each a through hole.

[0032] The pair of cylinder pin receiving portions 142a and the pair of first boom pin receiving portions 142b are substantially similar to the pair of cylinder pin receiving portions 1411, 1412 and the pair of boom pin receiving portions 141b of the tip boom 141, respectively.

[0033] For ease of explanation, the illustration shows the pair of first boom pin receiving portions 142b and the pair of cylinder pin receiving portions 142a as being offset in the axial direction of the telescopic boom 14. In reality, the pair of first boom pin receiving portions 142b and the pair of cylinder pin receiving portions 142a are aligned in the axial direction of the telescopic boom 14 and are provided at offset positions in the circumferential direction of the telescopic boom 14.

[0034] The pair of third boom pin receiving portions 142d are provided coaxially with each other and closer to the base end than the pair of first boom pin receiving portions 142b. A pair of boom connecting pins 144b are inserted into the pair of third boom pin receiving portions 142d, respectively. The pair of boom connecting pins 144b connect the intermediate boom 142 and the base boom 143.

[0035] The pair of second boom pin receiving portions 142c are provided coaxially with each other at the tip of the intermediate boom 142. A pair of boom connecting pins 144a are inserted into the pair of second boom pin receiving portions 142c, respectively.

[0036] The actuator 2 is an actuator that extends and retracts the telescopic boom 14. As shown in FIGS. 2A to 4C, the actuator 2 has a telescopic cylinder 3 and a pin moving mechanism 4. The actuator 2 is disposed in the internal space of the tip boom 141 when the telescopic boom 14 is in the retracted state (the state shown in FIG. 2A).

[0037] The telescopic cylinder 3 is an example of an extension device and includes a rod member 31 and a cylinder member 32. The telescopic cylinder 3 moves a boom connected to the cylinder member 32 via cylinder connecting pins 454A and 454B, which will be described later.

[0038] The pin moving mechanism 4 is an example of a moving mechanism and includes an electric motor 41, a brake mechanism 42, a transmission mechanism 43, a cylinder connecting mechanism 45, a boom connecting mechanism 46, a switching mechanism 47, and a position information detecting device 48, all of which are supported by a trunnion (not shown).

[0039] Hereinafter, each member constituting the actuator 2 will be described based on the state in which each member is incorporated into the actuator 2.

[0040] The trunnion (not shown) is fixed to the cylinder member 32 of the telescopic cylinder 3. Therefore, the pin moving mechanism 4 is supported by the cylinder member 32 of the telescopic cylinder 3. The pin moving mechanism 4 moves together with the cylinder member 32 in the extension / retraction direction of the telescopic boom 14 (in other words, in the axial direction of the telescopic boom 14). The cylinder member 32 is an example of a movable part of an actuator.

[0041] Such a trunnion unitizes the above-mentioned elements that make up the pin moving mechanism 4. Such a configuration contributes to a smaller size of the pin moving mechanism 4, improved productivity, and improved system reliability.

[0042] The electric motor 41 is, for example, a brushed DC motor or a brushless motor. The electric motor 41 is supported by a trunnion (not shown). As shown in FIGS. 3A to 4C, the electric motor 41 is connected to a reducer 431. The electric motor 41 is connected to, for example, a power supply device (not shown) provided on the swivel base 12 via a power supply cable.

[0043] The brake mechanism 42 is a so-called electromagnetic brake, and applies a braking force to the electric motor 41. The brake mechanism 42 prevents the rotation of the output shaft of the electric motor 41 when the electric motor 41 is stopped. This maintains the state of the pin moving mechanism 4 when the electric motor 41 is stopped.

[0044] The brake mechanism 42 is connected via a power supply cable to, for example, a power supply device (not shown) provided on the swivel base 12. Note that a position information detection device 48 (described later) is also connected via a power supply cable to, for example, a power supply device (not shown) provided on the swivel base 12.

[0045] Specifically, the brake mechanism 42 operates when the cylinder coupling mechanism 45 or the boom coupling mechanism 46, which will be described later, is in a contracted state, to maintain the states of the cylinder coupling mechanism 45 and the boom coupling mechanism 46. The state of the brake mechanism 42 is switched by a control unit (not shown). Alternatively, the state of the brake mechanism 42 may be switched based on an operation by an operator. The operation of the brake mechanism 42 will be described later.

[0046] The transmission mechanism 43 transmits the power of the electric motor 41 to the cylinder connecting mechanism 45 and the boom connecting mechanism 46. The transmission mechanism 43 includes a reducer 431 and a transmission shaft 432.

[0047] The reducer 431 reduces the rotation of the electric motor 41 and transmits the reduced rotation to a transmission shaft 432. The transmission shaft 432 transmits the rotation of the reducer 431 to a switching mechanism 47, which will be described later. In addition, a position information detection device 48 is provided at the tip of the transmission shaft 432, which detects information relating to the positions of the cylinder connecting pins 454A, 454B and the pair of boom connecting pins 144a, 144b.

[0048] The information relating to the positions of the cylinder connecting pins 454A, 454B and the pair of boom connecting pins 144a, 144b is, for example, the rotation angle of the electric motor 41 (specifically, the rotation angle of the transmission shaft 432). The rotation angle of the electric motor 41 (specifically, the rotation angle of the transmission shaft 432) corresponds to the amount of movement of the cylinder connecting pins 454A, 454B or the pair of boom connecting pins 144a, 144b from a reference position.

[0049] The positions of the cylinder connecting pins 454A, 454B shown in Fig. 3A are the reference positions of the cylinder connecting pins 454A, 454B. Also, the positions of the pair of boom connecting pins 144a shown in Fig. 4A are the reference positions of the boom connecting pins 144a.

[0050] The switching mechanism 47 is selectively connected to one of a cylinder connecting mechanism 45 and a boom connecting mechanism 46, which will be described later, and transmits the power of the electric motor 41 to one of the connecting mechanisms.

[0051] The switching mechanism 47 has a switch gear 471. The switch gear 471 is fitted and fixed to the outside of the transmission shaft 432, and selectively transmits the power of the electric motor 41 to either the cylinder connection mechanism 45 or the boom connection mechanism 46.

[0052] Here, the rotation direction of the switch gear 471 when the cylinder coupling mechanism 45 transitions from the extended state to the contracted state (the direction indicated by the arrow A1 in FIGS. 3A to 3C) is defined as a first rotation direction of the switch gear 471. Also, the rotation direction of the switch gear 471 when the cylinder coupling mechanism 45 transitions from the contracted state to the extended state (the direction indicated by the arrow A2 in FIGS. 3A to 3C) is defined as a second rotation direction of the switch gear 471.

[0053] The first rotation direction A1 of the switch gear 471 is also the rotation direction of the switch gear 471 when the boom connection mechanism 46 transitions from the retracted state (see FIG. 4C) to the extended state (see FIG. 4A). The second rotation direction A2 of the switch gear 471 is also the rotation direction of the switch gear 471 when the boom connection mechanism 46 transitions from the extended state (see FIG. 4A) to the retracted state (see FIG. 4C).

[0054] Furthermore, the position information detection device 48 is connected to a control unit 50 (see FIGS. 3A to 4C) provided on the swivel base 12 via a signal transmission cable. The power supply cable to the electric motor 41, the power supply cable to the brake mechanism 42, the power supply cable to the position information detection device 48, and the signal transmission cable of the position information detection device 48 are all combined into a single multi-core cable and arranged in the interior space of the telescopic boom 14. With this configuration, the interior space of the telescopic boom 14 can be used efficiently.

[0055] The cylinder coupling mechanism 45 is an example of a first coupling mechanism, which couples the boom with the telescopic cylinder 3 and releases the coupling using a motor. Specifically, the cylinder coupling mechanism 45 operates based on the power of the electric motor 41, and transitions between an extended state (see FIG. 3A) and a retracted state (see FIG. 3C).

[0056] 3A to 3C are schematic diagrams of the pin moving mechanism 4 as viewed from the base end side (rear side) of the telescopic boom 14. The operation of the cylinder connecting mechanism 45 transitioning from the extended state to the retracted state is the extraction operation of the cylinder connecting mechanism 45. The operation of the cylinder connecting mechanism 45 transitioning from the retracted state to the extended state is the engagement operation of the cylinder connecting mechanism 45.

[0057] When the cylinder connecting mechanism 45 is in the expanded state, the cylinder connecting pins 454A, 454B are engaged with the cylinder pin receiving portions 1411, 1412 of the boom (for example, the distal boom portion 141). In this engaged state, the boom and the cylinder member 32 (see FIGS. 2A to 2E) are connected.

[0058] Furthermore, when the cylinder connecting mechanism 45 is in the contracted state, the cylinder connecting pins 454A, 454B are disengaged from the cylinder pin receiving portions 1411, 1412. In this disengaged state, the boom and the cylinder member 32 are disengaged.

[0059] Specifically, the cylinder connecting mechanism 45 includes a first rack bar 451 , a first gear mechanism 452 , a second gear mechanism 453 , cylinder connecting pins 454 A and 454 B, and a first biasing mechanism 455 .

[0060] The first rack bar 451 moves in its axial direction in response to power (specifically, rotation) transmitted from the switching mechanism 47 (specifically, switch gear 471). The first rack bar 451 is located at a first predetermined position of the first rack bar 451 when the cylinder coupling mechanism 45 is in the expanded state (see FIG. 3A).

[0061] On the other hand, when the cylinder coupling mechanism 45 is in a contracted state (see FIG. 3C), the first rack bar 451 is located at the second predetermined position of the first rack bar 451. That is, the first rack bar 451 moves between the first predetermined position of the first rack bar 451 and the second predetermined position of the first rack bar 451.

[0062] In the expanded state, when the switch gear 471 rotates in the first rotation direction A1, the first rack tooth portion of the first rack bar 451 meshes with the tooth portion of the switch gear 471. When the switch gear 471 further rotates in the first rotation direction A1 from this state, the first rack bar 451 moves in accordance with the rotation of the switch gear 471.

[0063] The first rack bar 451 has a second rack tooth portion and a third rack tooth portion. The second rack tooth portion meshes with a first gear mechanism 452 (described later). The third rack tooth portion meshes with a second gear mechanism 453 (described later).

[0064] The first gear mechanism 452 rotates in response to the movement of the first rack bar 451. The first gear mechanism 452 also meshes with a cylinder connecting pin 454A, which will be described later.

[0065] The second gear mechanism 453 rotates in response to the movement of the first rack bar 451. In addition, the second gear mechanism 453 is in mesh with a cylinder connecting pin 454B, which will be described later.

[0066] The cylinder connecting pins 454A, 454B are arranged on the same straight line. Such cylinder connecting pins 454A, 454B are supported by a trunnion (not shown). The cylinder connecting pins 454A, 454B move in their axial directions in response to the rotation of the first gear mechanism 452 and the second gear mechanism 453.

[0067] When the electric motor 41 is de-energized and the brake mechanism 42 is turned OFF while the cylinder connecting mechanism 45 is in the contracted state (see FIG. 3C), the first biasing mechanism 455 returns the cylinder connecting mechanism 45 to the expanded state.

[0068] In other words, when the cylinder connecting mechanism 45 is in a contracted state, the first biasing mechanism 455 returns the cylinder connecting pins 454A, 454B to the reference position (in other words, the engaged state) when the electric motor 41 is in a non-energized state (stopped state) and the brake mechanism 42 is in an OFF state.

[0069] Specifically, the first biasing mechanism 455 has a pair of coil springs 455a, 455b (see FIG. 3A). The coil spring 455a is provided between a trunnion (not shown) and the cylinder connecting pin 454A.

[0070] The coil spring 455a constantly biases the cylinder connecting pin 454A. The direction in which the coil spring 455a biases the cylinder connecting pin 454A coincides with the direction from the base end portion to the tip end portion of the cylinder connecting pin 454A.

[0071] The coil spring 455b is provided between the trunnion (not shown) and the cylinder connecting pin 454B. The coil spring 455b constantly biases the cylinder connecting pin 454B. The direction in which the coil spring 455b biases the cylinder connecting pin 454B coincides with the direction from the base end to the tip end of the cylinder connecting pin 454B.

[0072] The configuration of the first biasing mechanism 455 as described above contributes to the miniaturization of the pin moving mechanism 4. The arrangement of the coil springs 455a and 455b is not limited to that of this embodiment. The operation of the cylinder connecting mechanism 45 will be described later.

[0073] The boom connection mechanism 46 is an example of a second connection mechanism, which connects adjacent booms together and releases the connection using a motor. Specifically, the boom connection mechanism 46 transitions between an extended state (see FIG. 4A) and a retracted state (see FIG. 4C) based on the rotation of the electric motor 41.

[0074] The operation of the boom connection mechanism 46 transitioning from the extended state to the retracted state is the retraction operation of the boom connection mechanism 46. The operation of the boom connection mechanism 46 transitioning from the retracted state to the extended state is the retraction operation of the boom connection mechanism 46.

[0075] In the extended state, the boom connection mechanism 46 can be in either an engaged state or a disengaged state with respect to a boom connection pin (for example, a pair of boom connection pins 144a). When the boom connection mechanism 46 is engaged with the boom connection pin, it transitions from the extended state to the retracted state, thereby disengaging the boom connection pin from the boom.

[0076] Furthermore, the boom connecting mechanism 46, while engaged with the boom connecting pin, transitions from a contracted state to an extended state, thereby engaging the boom connecting pin with the boom.

[0077] As shown in FIGS. 4A to 4C, the boom connecting mechanism 46 includes a pair of second rack bars 461a and 461b, a synchronization gear 462, and a second biasing mechanism 463.

[0078] The pair of second rack bars 461a, 461b are, for example, shaft members that are long in the left-right direction and are arranged in parallel and spaced apart in the front-rear direction. The pair of second rack bars 461a, 461b are each arranged above the first rack bar 451 of the cylinder linking mechanism 45.

[0079] The pair of second rack bars 461a, 461b each have a synchronizing rack tooth portion on an opposing surface. Each of the synchronizing rack tooth portions is meshed with a synchronizing gear 462. When the synchronizing gear 462 rotates, the one second rack bar 461a and the other second rack bar 461b move in opposite directions in the axial direction of the second rack bars 461a, 461b.

[0080] The pair of second rack bars 461a, 461b each have a locking claw portion at the tip thereof, which engages with the boom connecting pins (for example, boom connecting pins 144a, 144b) when the boom connecting pins are moved.

[0081] One of the second rack bars 461a moves in its axial direction in response to power (specifically, rotation) transmitted from the switching mechanism 47 (specifically, switch gear 471). One of the second rack bars 461a is located at a first predetermined position of the second rack bar 461a when the boom connection mechanism 46 is in the extended state. Also, one of the second rack bars 461a is located at a second predetermined position of the second rack bar 461a when the boom connection mechanism 46 is in the retracted state. In other words, one of the second rack bars 461a moves between the first predetermined position of the second rack bar 461a and the second predetermined position of the second rack bar 461a.

[0082] When the switch gear 471 of the switching mechanism 47 rotates in the second rotation direction A2 from the extended state of the boom connection mechanism 46, the rack teeth portion of one of the second rack bars 461a meshes with the teeth portion of the switch gear 471. When the switch gear 471 further rotates in the second rotation direction A2 from this state, one of the second rack bars 461a moves in its axial direction in response to the rotation of the switch gear 471.

[0083] Furthermore, when one second rack bar 461a moves, the synchronization gear 462 rotates, and the other second rack bar 461b moves in its axial direction. The movement direction of one second rack bar 461a is opposite to the movement direction of the other second rack bar 461b.

[0084] When the electric motor 41 is de-energized and the brake mechanism 42 is turned off while the boom connection mechanism 46 is in the contracted state, the second biasing mechanism 463 returns the boom connection mechanism 46 to the extended state. The second biasing mechanism 463 biases the pair of second rack bars 461a, 461b in directions away from each other.

[0085] In other words, when the boom connecting mechanism 46 is in a contracted state, the second biasing mechanism 463 returns the boom connecting pin 144a to the reference position (in other words, the engaged state) when the electric motor 41 is in a non-energized state (stopped state) and the brake mechanism 42 is in an OFF state.

[0086] Specifically, the second biasing mechanism 463 is composed of a pair of coil springs 463a, 463b. The pair of coil springs 463a, 463b bias the base ends of the pair of second rack bars 461a, 461b toward the tip ends, respectively.

[0087] The position information detection device 48 is a non-contact potentiometer. The position information detection device 48 has a detection object (not shown) and a sensor (not shown). The detection object is a magnet, and is fixed to the transmission shaft 432. The detection object rotates together with the transmission shaft 432.

[0088] The object to be detected may be provided on a member that rotates together with the output shaft of the electric motor 41. Therefore, the object to be detected rotates together with the output shaft of the electric motor 41.

[0089] The sensor has a Hall element and is provided facing the object to be detected in a predetermined direction. For example, the sensor may be fixed to a trunnion (not shown) via a support.

[0090] The sensor outputs a voltage corresponding to the phase of the object to be detected. That is, the sensor outputs a voltage corresponding to the rotation angle of the transmission shaft 432 to which the object to be detected is fixed (that is, the rotation angle of the electric motor 41).

[0091] The position information detecting device 48 detects information relating to the positions (in other words, the states) of the cylinder connecting pins 454A, 454B in accordance with the detection values ​​of the sensors. The position information detecting device 48 also detects information relating to the position of the boom connecting pin 144a in accordance with the detection values ​​of the sensors.

[0092] The information regarding the positions (in other words, the states) of the cylinder connecting pins 454A, 454B and the information regarding the position of the boom connecting pin 144a is the rotation angle of the electric motor 41 from the reference position (specifically, the rotation angle of the transmission shaft 432).

[0093] Fig. 5A is a diagram showing the detection area of ​​the position information detection device 48. Fig. 5B is a schematic diagram showing the positional relationship between the detection area of ​​the position information detection device 48 and the cylinder connecting pin. Fig. 5C is a schematic diagram showing the positional relationship between the detection area of ​​the position information detection device 48 and the boom connecting pin.

[0094] 5A to 5C indicates the position where the rotation angle of the electric motor 41 is 0° (hereinafter referred to as the reference position). The dashed dotted line L1 also indicates the position where the rotation angle of the transmission shaft 432 and the switch gear 471 is 0°. The rotation angle of the electric motor 41 means the angle by which the output shaft of the electric motor 41 rotates from the reference position.

[0095] The state in which the rotation angle of the electric motor 41 is 0° is referred to as the reference state of the electric motor 41. The state in which the rotation angle of the electric motor 41 is 0° is also the reference state of the transmission shaft 432 and the switch gear 471. The state in which the rotation angle of the electric motor 41 is 0° is also the reference state of the cylinder linkage mechanism 45 and the boom linkage mechanism 46.

[0096] In the reference state of the electric motor 41, the cylinder coupling mechanism 45 is in the expanded state shown in Fig. 3A. In the reference state of the electric motor 41, the cylinder coupling pins 454A and 454B are in the engaged state.

[0097] When the electric motor 41 is in the reference state, the cylinder connecting pins 454A and 454B are located at the position of the cylinder connecting pin CP1 in FIG. 5B.

[0098] 5B shows cylinder connecting pins CP1 to CP4. When the cylinder connecting mechanism 45 transitions from the expanded state to the contracted state, the cylinder connecting pins 454A and 454B transition from the state of cylinder connecting pin CP1 to the state of cylinder connecting pins CP2 and CP3, and then to the state of cylinder connecting pin CP4.

[0099] Furthermore, when the electric motor 41 is in the standard state, the boom connection mechanism 46 is in the extended state shown in Fig. 4A. When the boom connection mechanism 46 is in the extended state, the boom connection pin 144a is in the engaged state.

[0100] When the electric motor 41 is in the reference state, the boom connecting pin 144a is located at the position of the boom connecting pin BP1 in FIG. 5C.

[0101] 5C shows boom connecting pins BP1 to BP4. When the boom connecting mechanism 46 transitions from the extended state to the retracted state while engaged with the boom connecting pin 144a, the boom connecting pin 144a transitions from the state of boom connecting pin BP1 to the state of boom connecting pins BP2 and BP3, and then to the state of boom connecting pin BP4.

[0102] When the electric motor 41 rotates in the first rotation direction A1 from the reference position, the cylinder coupling mechanism 45 is actuated. When the electric motor 41 rotates in the second rotation direction A2 from the reference position, the boom coupling mechanism 46 is actuated. For ease of explanation, angles on the first rotation direction A1 side from the reference position will be represented as negative angles. On the other hand, angles on the second rotation direction A2 side from the reference position will be represented as positive angles.

[0103] The position information detection device 48 detects information relating to the positions of the cylinder connecting pins 454A, 454B and the boom connecting pin 144a according to the rotation angle of the electric motor 41 (specifically, the transmission shaft 432).

[0104] First, with reference to Figures 5A and 5B, a case where the electric motor 41 rotates in the first rotation direction A1 from the reference position will be described. When the electric motor 41 rotates in the first rotation direction A1 from the reference position, the cylinder coupling mechanism 45 transitions from the expanded state to the contracted state. Such operation of the cylinder coupling mechanism 45 is controlled by the control unit 50 (see Figures 3A to 3C).

[0105] Hereinafter, the control by the control unit 50 to transition the cylinder connecting mechanism 45 from the extended state to the contracted state will be referred to as cylinder connecting pin removal control. In the cylinder connecting pin removal control, the position information detection device 48 determines that the cylinder connecting pins 454A, 454B are in the inserted state when the detected angle is included in the first detection region R1 (see FIGS. 5A and 5B).

[0106] The first detection region R1 is a region from the reference position to a first predetermined angle θ1 (see FIGS. 5A and 5B). The first predetermined angle θ1 may be, for example, −20°. When the rotation angle of the electric motor 41 is the first predetermined angle θ1, the cylinder connecting pins 454A and 454B are located at the position of the cylinder connecting pin CP2 in FIG. 5B.

[0107] In the control of cylinder connecting pin removal, cylinder connecting pins 454A, 454B move in the direction of arrow A3 shown in Fig. 5B. The direction of arrow A3 shown in Fig. 5B is referred to as the cylinder connecting pin removal direction.

[0108] Furthermore, in the removal control of the cylinder connecting pins, the position information detection device 48 determines that the cylinder connecting pins 454A, 454B are in the intermediate state when the detected angle is included in the second detection region R2 (see FIGS. 5A and 5B).

[0109] The second detection region R2 is a region from the first predetermined angle θ1 to the second predetermined angle θ2 (see FIGS. 5A and 5B). The second predetermined angle θ2 may be, for example, −65°. The second predetermined angle θ2 is an example of the first angle.

[0110] When the angle detected by the position information detector 48 is the second predetermined angle θ2, the cylinder connecting pins 454A and 454B are located at the position of the cylinder connecting pin CP3 in FIG. 5B.

[0111] The dashed two-dot line L in FIG. a indicates the inner end surfaces 1413 of the cylinder pin receiving portions 1411 and 1412 (see FIG. 6).

[0112] When the detection angle of the position information detection device 48 is the second predetermined angle θ2, as shown in Figures 5B and 6, the tip surfaces 454a of the cylinder connecting pins 454A and 454B and the inner end surfaces 1413 of the cylinder pin receiving portions 1411 and 1412 are located on the same plane.

[0113] When the detection angle of the position information detection device 48 is the second predetermined angle θ2, the position of the tip surfaces 454a of the cylinder connecting pins 454A, 454B may be slightly shifted in the left-right direction in FIG. 6 from the state shown in FIG. 6.

[0114] The position of the cylinder connecting pin CP3 shown in Fig. 5B and the positions of the cylinder connecting pins 454A, 454B shown in Fig. 6 correspond to an example of the first position of the cylinder connecting pin. When the cylinder connecting pins 454A, 454B are in the first position, they release the connection between the boom and the telescopic cylinder 3.

[0115] In this way, the first position of the cylinder connecting pin is the theoretical (in other words, design) position where the boom is released from the connection with the telescopic cylinder 3. This first position is determined by the fit between the cylinder connecting pins 454A, 454B and the cylinder pin receivers 1411, 1412.

[0116] Furthermore, the position information detection device 48 determines that the cylinder connecting pins 454A, 454B are in the removed state when the detected angle is included in a third detection region R3 (see FIGS. 5A and 5B). The third detection region R3 is a region from the second predetermined angle θ2 to a third predetermined angle θ3 (see FIGS. 5A and 5B). The third predetermined angle may be, for example, −95°.

[0117] In the cylinder connecting pin removal control, the cylinder connecting pins 454A, 454B move a predetermined distance in the removal direction. This predetermined distance is referred to as the stroke amount S1 of the cylinder connecting pin (see FIG. 5B). Furthermore, in the cylinder connecting pin removal control, the movement speed of the cylinder connecting pin is a first predetermined speed. In other words, in the cylinder connecting pin removal control, the cylinder connecting pin moves the stroke amount S1 at the first predetermined speed.

[0118] 5B is the stroke end in the withdrawal direction of the cylinder connecting pin (hereinafter referred to as the stroke end). When the cylinder connecting pin is positioned at the stroke end, the rotation angle of the electric motor 41 is an angle between the second predetermined angle θ2 and the third predetermined angle θ3.

[0119] In this embodiment, the position information detection device 48 cannot accurately identify (in other words, detect) the rotation angle of the electric motor 41 when the cylinder connecting pins 454A, 454B are located at the position of the cylinder connecting pin CP4 in Figure 5B (i.e., the stroke end).

[0120] Next, with reference to Figures 5A and 5C, a case where the electric motor 41 rotates from the reference position in the second rotation direction A2 (see Figures 5A and 5C) will be described. When the electric motor 41 rotates from the reference position in the second rotation direction A2, the boom connection mechanism 46 transitions from the extended state to the retracted state. Such operation of the boom connection mechanism 46 is controlled by the control unit 50 (see Figures 4A to 4C).

[0121] Hereinafter, the control performed by the control unit 50 to transition the boom connecting mechanism 46 from the extended state to the retracted state will be referred to as boom connecting pin removal control. During the boom connecting pin removal control, the position information detection device 48 determines that the boom connecting pin 144a is in the retracted state when the detected angle is included in the fourth detection region R4 (see FIGS. 5A and 5C).

[0122] The fourth detection region R4 is a region from the reference position to a fourth predetermined angle θ4 (see FIGS. 5A and 5C). The fourth predetermined angle θ4 may be, for example, 10°. When the rotation angle of the electric motor 41 is the fourth predetermined angle θ4, the boom connecting pin 144a is located at the position of the boom connecting pin BP2 in FIG. 5C.

[0123] In the control of removing the boom connecting pin, the boom connecting pin 144a moves in the direction of arrow A4 shown in Fig. 5C (see Figs. 5A and 5C). The direction of arrow A4 shown in Fig. 5C is referred to as the removing direction of the boom connecting pin.

[0124] Furthermore, during the removal control of the boom connecting pin, the position information detection device 48 determines that the boom connecting pin 144a is in the intermediate state when the detected angle is included in a fifth detection region R5 (see FIGS. 5A and 5C). The fifth detection region R5 is a region from the fourth predetermined angle θ4 to a fifth predetermined angle θ5 (see FIGS. 5A and 5C). The fifth predetermined angle θ5 may be, for example, 65°. The fifth predetermined angle θ5 is an example of the second angle.

[0125] When the rotation angle of the electric motor 41 is the fifth predetermined angle θ5, the boom connecting pin 144a is located at the position of the boom connecting pin BP3 in FIG. 5C.

[0126] The dashed double-dashed line L in Figure 5C b indicates an inner end surface 142e (see FIG. 7) of the first boom pin receiving portion 142b.

[0127] When the angle detected by the position information detecting device 48 is the fifth predetermined angle θ5, the tip surface 144c of the boom connecting pin 144a and the inner end surface 142e of the first boom pin receiving portion 142b are located on the same plane as shown in Fig. 7. Note that when the angle detected by the position information detecting device 48 is the fifth predetermined angle θ5, the position of the tip surface 144c of the boom connecting pin 144a may be slightly shifted in the left-right direction in Fig. 7 from the state shown in Fig. 7.

[0128] The position of the boom connecting pin BP3 shown in Fig. 5C and the position of the boom connecting pin 144a shown in Fig. 7 correspond to an example of the first position of the boom connecting pin. When the boom connecting pin 144a is in the first position of the boom connecting pin, the connection between adjacent booms is released.

[0129] In this way, the first position of the boom connecting pin is the theoretical (in other words, designed) position where the connection between adjacent booms is released. This first position is determined by the fit between the boom connecting pin 144a and the first boom pin receiver 142b.

[0130] Furthermore, the position information detecting device 48 determines that the boom connecting pin 144a is in the removed state when the detected angle is included in a sixth detection region R6 (see FIGS. 5A and 5C). The sixth detection region R6 is a region from the fifth predetermined angle θ5 to a sixth predetermined angle θ6 (see FIGS. 5A and 5C). The sixth predetermined angle θ6 may be, for example, 95°.

[0131] In the boom connecting pin withdrawal control, the boom connecting pin 144a moves a predetermined distance in the withdrawal direction. This predetermined distance is called the boom connecting pin stroke amount S2 (see FIGS. 5A and 5C). Furthermore, in the boom connecting pin withdrawal control, the boom connecting pin moves at a second predetermined speed. That is, in the boom connecting pin withdrawal control, the boom connecting pin moves the stroke amount S2 at the second predetermined speed.

[0132] 5C is the stroke end in the direction in which the boom connecting pin is removed (hereinafter referred to as the stroke end). When the boom connecting pin is positioned at the stroke end, the rotation angle of the electric motor 41 is an angle between the fifth predetermined angle θ5 and the sixth predetermined angle θ6.

[0133] In this embodiment, the position information detection device 48 cannot accurately identify (in other words, detect) the rotation angle of the electric motor 41 when the boom connecting pin 144a is located at the position of the boom connecting pin BP4 in Figure 5C (i.e., the stroke end).

[0134] An example of the operation of the cylinder connecting mechanism 45 and the boom connecting mechanism 46 will now be described.

[0135] 2A to 2E and 3A to 3C, an example of the operation of the cylinder coupling mechanism 45 will be described. The operation of the cylinder coupling mechanism 45 is the operation when the cylinder coupling mechanism 45 transitions from the expanded state to the contracted state based on the power of the electric motor 41, and the operation when the cylinder coupling mechanism 45 transitions from the contracted state to the expanded state based on the biasing force of the first biasing mechanism 455.

[0136] Fig. 3A is a schematic diagram showing the expanded state of the cylinder coupling mechanism 45 and the engagement state between the pair of cylinder coupling pins 454A, 454B and the pair of cylinder pin receivers 1411, 1412 of the tip boom 141. Fig. 3B is a schematic diagram showing the state of the cylinder coupling mechanism 45 in the middle of transitioning from the expanded state to the contracted state.

[0137] 3C is a schematic diagram showing a state in which the cylinder connecting mechanism 45 is contracted and the pair of cylinder connecting pins 454A, 454B and the pair of cylinder pin receiving portions 1411, 1412 of the tip boom 141 are separated from each other.

[0138] The expanded state of the cylinder coupling mechanism 45 shown in Fig. 3A corresponds to the state of the cylinder coupling mechanism 45 in Fig. 2A to Fig. 2D. The state of the cylinder coupling mechanism 45 shown in Fig. 3B corresponds to a state in which the cylinder coupling mechanism 45 is in transition from the state shown in Fig. 2D to the state shown in Fig. 2E. The contracted state of the cylinder coupling mechanism 45 shown in Fig. 3C corresponds to the state of the cylinder coupling mechanism 45 shown in Fig. 2E.

[0139] When the cylinder linking mechanism 45 transitions from the extended state to the retracted state, the control unit 50 (see FIGS. 3A to 3C) drives the electric motor 41. The power of the electric motor 41 is transmitted to a pair of cylinder linking pins 454A, 454B via the first and second transmission paths described below. The control unit 50 may actually be configured such that a CPU, ROM, RAM, and HDD are connected via a bus, or may be configured such that it is composed of a one-chip LSI.

[0140] The first transmission path is a path through which the power of the electric motor 41 is transmitted in the following order. (First transmission path) Switch gear 471 → First rack bar 451 → First gear mechanism 452 → Right cylinder connecting pin 454A

[0141] The second transmission path is a path through which the power of the electric motor 41 is transmitted in the following order. (Second transmission path) Switch gear 471 → First rack bar 451 → Second gear mechanism 453 → Left cylinder connecting pin 454B

[0142] Specifically, first, in the first transmission path and the second transmission path, the switch gear 471 rotates in a first rotation direction (the direction indicated by the arrow A1 in FIG. 3A) based on the power of the electric motor 41.

[0143] In the first transmission path, when the switch gear 471 rotates in the first direction, the first rack bar 451 moves to the right in response to the rotation. In the description of the operation of the cylinder coupling mechanism 45, the right side and the left side refer to the right side and the left side in Figures 3A to 3C.

[0144] In the first transmission path, when the first rack bar 451 moves to the right, the right cylinder connecting pin 454A moves to the left via the first gear mechanism 452. On the other hand, in the second transmission path, when the first rack bar 451 moves to the right, the left cylinder connecting pin 454B moves to the right via the second gear mechanism 453.

[0145] The position information detection device 48 detects the positions of the pair of cylinder connecting pins 454A, 454B. The position information detection device 48 sends the detected value to the control unit 50. The control unit 50 controls the brake mechanism 42 and the electric motor 41 based on the detected value obtained from the position information detection device 48.

[0146] In this embodiment, when the detection value of the position information detection device 48 satisfies a predetermined condition, the control unit 50 supplies power to the brake mechanism 42 to turn on the brake mechanism 42. In the on state, the brake mechanism 42 applies a braking force to the electric motor 41.

[0147] As a result, the operation of the cylinder connecting mechanism 45 is restricted. In other words, the cylinder connecting mechanism 45 is maintained in a contracted state. That is, the positions of the pair of cylinder connecting pins 454A, 454B are maintained. Thereafter, the control unit 50 stops the electric motor 41. Such control by the control unit 50 is referred to as brake control. Brake control will be described later.

[0148] Next, an example of the operation of the boom linkage mechanism 46 will be described with reference to FIGS. 2A to 2E and 4A to 4C.

[0149] Fig. 4A is a schematic diagram showing the boom connection mechanism 46 in an extended state, and an engaged state between the pair of boom connection pins 144a and the pair of first boom pin receivers 142b of the intermediate boom 142. Fig. 4B is a schematic diagram showing the boom connection mechanism 46 in the middle of transitioning from the extended state to the retracted state. Furthermore, Fig. 4C is a schematic diagram showing the boom connection mechanism 46 in a retracted state, and a disengaged state between the pair of boom connection pins 144a and the pair of first boom pin receivers 142b of the intermediate boom 142.

[0150] The extended state of the boom connection mechanism 46 shown in Fig. 4A corresponds to the state of the boom connection mechanism 46 in Fig. 2A. The state of the boom connection mechanism 46 shown in Fig. 4B corresponds to a state in which the boom connection mechanism 46 is in transition from the state shown in Fig. 2A to the state shown in Fig. 2B. The retracted state of the boom connection mechanism 46 shown in Fig. 4C corresponds to the state of the boom connection mechanism 46 shown in Fig. 2B.

[0151] The boom linkage mechanism 46 transitions between an extended state and a retracted state based on the power of the electric motor 41. Here, the position of the switch gear 471 shown in FIG.

[0152] When the boom connection mechanism 46 transitions from the extended state to the retracted state, the control unit 50 (see FIGS. 4A to 4C) drives the electric motor 41 in the direction opposite to the direction in which the cylinder connection mechanism 45 is operated. The power of the electric motor 41 is transmitted through the following path. (Transmission path) Switch gear 471 → one second rack bar 461a → synchronous gear 462 → other second rack bar 461b

[0153] First, in the transmission path, the switch gear 47 rotates in the second rotation direction (the direction indicated by the arrow A2 in FIG. 4A) based on the power of the electric motor 41. Then, the teeth of the switch gear 471 mesh with the rack teeth of one of the second rack bars 461a.

[0154] From this state, when the switch gear 471 further rotates in the second rotation direction A2, one of the second rack bars 461a moves to the right in Fig. 4A in accordance with the rotation of the switch gear 471. In the description of the operation of the boom connecting mechanism 46, the right side and the left side refer to the right side and the left side in Figs. 4A to 4C.

[0155] Then, in response to the movement of one second rack bar 461a to the right, the synchronization gear 462 rotates. Then, in response to the rotation of the synchronization gear 462, the other second rack bar 461b moves to the left.

[0156] When the pair of second rack bars 461a, 461b are engaged with the pair of boom connecting pins 144a and transition from the extended state to the retracted state, the pair of boom connecting pins 144a disengage from the pair of first boom pin receiving portions 142b of the intermediate boom 142 (see Figure 4C).

[0157] The position information detection device 48 is an example of a detection unit, and detects the positions of the pair of boom connecting pins 144a. The position information detection device 48 sends the detected value to the control unit 50. The control unit 50 controls the brake mechanism 42 and the electric motor 41 based on the detected value acquired from the position information detection device 48.

[0158] In this embodiment, when the detection value of the position information detection device 48 satisfies a predetermined condition, the control unit 50 supplies power to the brake mechanism 42 to turn the brake mechanism on. In the on state, the brake mechanism 42 applies a braking force to the electric motor 41.

[0159] As a result, the operation of the boom connection mechanism 46 is restricted. In other words, the boom connection mechanism 46 is maintained in a retracted state. That is, the positions of the pair of boom connection pins 144a are maintained. Thereafter, the control unit 50 stops the electric motor 41. Such control by the control unit 50 is referred to as brake control. Brake control will be described later.

[0160] The brake control will be described below with reference to Fig. 8. As described above, the control unit 50 performs the brake control when transitioning the cylinder coupling mechanism 45 from the extended state to the retracted state. The control unit 50 also performs the brake control when transitioning the boom coupling mechanism 46 from the extended state to the retracted state.

[0161] In other words, the control unit 50 performs brake control in the removal control of the cylinder connecting pin and the removal control of the boom connecting pin. The brake control in the removal control of the boom connecting pin is substantially the same as the brake control in the removal control of the cylinder connecting pin.

[0162] The brake control during the removal control of the cylinder connecting pin will be described below. The brake control during the removal control of the boom connecting pin may be applied to the brake control during the removal control of the cylinder connecting pin, which will be described later, by appropriately changing the description.

[0163] 8 is a flowchart showing the brake control process. As described above, in the control of removing the cylinder connecting pins, the control unit 50 drives the electric motor 41 to operate the cylinder connecting mechanism 45. At this time, the position information detection device 48 detects the rotation angle of the electric motor 41 (specifically, the rotation angle of the transmission shaft 432) as information about the positions of the cylinder connecting pins 454A, 454B.

[0164] The position information detector 48 sends information relating to the detected positions of the cylinder connecting pins 454A, 454B to the control unit 50. Hereinafter, the brake control in the removal control of the cylinder connecting pins will be described with reference to FIG.

[0165] First, in step S1 of FIG. 8, the control unit 50 acquires information about the positions of the cylinder connecting pins 454A and 454B from the position information detection device .

[0166] Next, in step S2 of FIG. 8, the control unit 50 determines whether or not the cylinder connecting pins 454A, 454B have reached a first position of the cylinder connecting pins that has been set in advance.

[0167] Specifically, the control unit 50 determines whether the rotation angle of the electric motor 41 (in other words, the transmission shaft 432) is the second predetermined angle θ2 (see Figures 5A and 5B) based on the information regarding the positions of the cylinder connecting pins 454A, 454B acquired in step S1.

[0168] When the rotation angle of the electric motor 41 (in other words, the transmission shaft 432) is the second predetermined angle θ2, the cylinder connecting pins 454A, 454B are located at the position of the cylinder connecting pin CP3 shown in FIG. 5B and the position of the cylinder connecting pins 454A, 454B shown in FIG. 6.

[0169] In this example, the position of the cylinder connecting pin CP3 shown in FIG. 5B and the positions of the cylinder connecting pins 454A, 454B shown in FIG. 6 are first positions of the cylinder connecting pins 454A, 454B.

[0170] The first positions of the cylinder connecting pins 454A, 454B are preset in relation to the moving speed of the cylinder connecting pins 454A, 454B. When the cylinder connecting pins 454A, 454B reach the first positions, the boom and the telescopic cylinder 3, which are connected by the cylinder connecting pins 454A, 454B, are released from their original positions.

[0171] If the cylinder connecting pins 454A, 454B have not reached the first position in step S2 ("NO" in step S2), the control unit 50 returns the control process to step S1.

[0172] On the other hand, if the cylinder connecting pins 454A, 454B have reached the first position in step S2 ("YES" in step S2), the control unit 50 advances the control process to step S3.

[0173] 8, the control unit 50 determines whether a first predetermined time has elapsed since the cylinder connecting pins 454A, 454B reached the first position. The first predetermined time is, for example, 0.5 seconds.

[0174] If the first predetermined time has not elapsed since the cylinder connecting pins 454A, 454B reached the first position in step S3 ("NO" in step S3), the control unit 50 repeats the process of step S3.

[0175] On the other hand, if the first predetermined time has elapsed since the cylinder connecting pins 454A, 454B reached the first position in step S3 ("YES" in step S3), the control unit 50 advances the control process to step S4.

[0176] While the control unit 50 repeats the process of step S3, the cylinder connecting pins 454A, 454B continue to move in the extraction direction at the first predetermined speed. Then, the cylinder connecting pins 454A, 454B move in the extraction direction for a first predetermined time after reaching the first position, and reach the stroke end of the cylinder connecting pins 454A, 454B in the extraction direction.

[0177] With this configuration, the cylinder connecting pins 454A, 454B can be completely removed during the removal control of the cylinder connecting pins, and therefore the extension and retraction operation of the telescopic boom 14 can be performed efficiently.

[0178] The stroke end of the cylinder connecting pins 454A, 454B in the removal direction is the position of the cylinder connecting pin CP4 shown in Fig. 5B. In this state, the cylinder connecting mechanism 45 is in a contracted state.

[0179] As described above, in this example, the first position of the cylinder connecting pins 454A, 454B is the theoretical position where the boom and the telescopic cylinder 3 are released from connection, and is determined by the engagement between the cylinder connecting pins 454A, 454B and the cylinder pin receivers 1411, 1412.

[0180] The first predetermined time is the time it takes for the cylinder connecting pins 454A, 454B to move from the first position to the stroke end at the first predetermined speed.

[0181] That is, the first predetermined time is determined by the relationship between the first position of the cylinder connecting pins 454A, 454B, the first predetermined speed which is the moving speed of the cylinder connecting pins 454A, 454B, and the distance from the first position to the stroke end.

[0182] Next, in step S4 of Fig. 8, the control unit 50 supplies power to the brake mechanism 42 to turn the brake mechanism 42 on. In the on state, the brake mechanism 42 applies a braking force to the electric motor 41. As a result, the state of the cylinder coupling mechanism 45 is maintained in the contracted state.

[0183] In this embodiment, as described above, the position information detection device 48 cannot accurately identify (in other words, detect) the rotation angle of the electric motor 41 when the cylinder connecting pins 454A, 454B are located at the position of the cylinder connecting pin CP4 in Figure 5B (i.e., the stroke end).

[0184] Meanwhile, the position information detection device 48 can accurately identify (in other words, detect) the rotation angle of the electric motor 41 when the cylinder connecting pins 454A, 454B are located at the position of the cylinder connecting pin CP3 in FIG. 5B (i.e., the first position).

[0185] In this embodiment, the timing to turn on the brake mechanism 42 is determined based on the state in which the cylinder connecting pins 454A, 454B reach the first position. Therefore, the control unit 50 can turn on the brake mechanism 42 when the cylinder connecting pins 454A, 454B have reliably reached the stroke end.

[0186] 8, the control unit 50 determines whether a second predetermined time has elapsed since the brake mechanism 42 was turned on. The second predetermined time is, for example, 0.3 seconds.

[0187] If the control unit 50 determines in step S5 that the second predetermined time has not elapsed since the brake mechanism 42 was turned on ("NO" in step S5), the control unit 50 repeats the process of step S5.

[0188] On the other hand, if the control unit 50 determines in step S5 that the second predetermined time has elapsed since the brake mechanism 42 was turned on ("YES" in step S5), the control process proceeds to step S6.

[0189] Next, in step S6 of Fig. 8, the control unit 50 stops the supply of power to the electric motor 41, thereby stopping the electric motor 41. In this state, the brake mechanism 42 maintains the cylinder coupling mechanism 45 in the contracted state. Then, the control unit 50 ends the brake control.

[0190] In this manner, in this embodiment, the control unit 50 stops the electric motor 41 when the second predetermined time has elapsed since the brake mechanism 42 was turned on. Therefore, the electric motor 41 does not operate excessively when the cylinder connecting pins 454A, 454B are positioned at the stroke end in the removal direction. As a result, damage to the electric motor 41 is suppressed.

[0191] (Actions and Effects of This Embodiment) The mobile crane 1 according to this embodiment as described above can maintain the state in which the booms are disconnected from the telescopic cylinder 3 by the cylinder connecting pins 454A, 454B, and the state in which adjacent booms are disconnected from each other by the boom connecting pin 144a. Other functions and effects obtained from the mobile crane 1 according to this embodiment are as described above.

[0192] <Additional Notes> The technical ideas disclosed in the specification and drawings include inventions obtained by arbitrarily combining the various configurations described in the above embodiments. In particular, the technical ideas disclosed in the specification and drawings include inventions obtained by arbitrarily applying the various configurations disclosed in the specification and drawings to the above basic configuration. [Industrial Applicability]

[0193] The crane according to the present invention is not limited to a rough terrain crane, but may be any of various mobile cranes, such as an all-terrain crane, a truck crane, or a loaded truck crane (also called a cargo crane).Furthermore, the crane according to the present invention is not limited to a mobile crane, but may be any other crane equipped with a telescopic boom. [Explanation of symbols]

[0194] 1. Mobile crane 10 Running body 12 Swivel table 14 Telescopic Boom 141 Tip boom 1411, 1412 Cylinder pin receiving part 1413 Inner end surface 141b Boom pin holder 142 Intermediate Boom 142a Cylinder pin receiving part 142b First boom pin holder 142c Second boom pin holder 142d Third boom pin holder 142e Inner end surface 143 Base boom 144a, 144b, BP1, BP2, BP3, BP4 boom connecting pin 144c Tip surface 16 Wire Rope 17 Hook 2 Actuators 3 Telescopic cylinder 31 Rod member 32 Cylinder parts 4 Pin moving mechanism 41 Electric motor 42 Brake mechanism 43 Transmission Mechanism 431 Reducer 432 Transmission shaft 45 Cylinder connection mechanism 451 First Rack Bar 452 First Gear Mechanism 453 Second Gear Mechanism 454A, 454B, CP1, CP2, CP3, CP4 cylinder connecting pin 454a Tip surface 455 First biasing mechanism 455a, 455b Coil spring 46 Boom connection mechanism 461a, 461b Second rack bar 462 Synchronous Gear 463 Second biasing mechanism 463a, 463b Coil spring 47 Switching mechanism 471 Switchgear 48 Location Information Detection Device 50 control section

Claims

1. a telescopic boom having a plurality of booms and extending and retracting by a telescopic device; a first pin that connects the boom and the telescopic device; a second pin connecting adjacent booms to each other; a movement mechanism that moves one of the first pin and the second pin in a removal direction by a motor to release the connection between the members connected by the one pin; a brake mechanism that brakes the motor; a control unit that controls the movement mechanism, the control unit turns on the brake mechanism after a first predetermined time has elapsed since the one pin reaches a preset first position during movement of the one pin; Work equipment.

2. the control unit stops the motor after a second predetermined time has elapsed since the brake mechanism was turned on. The work machine according to claim 1 .

3. When the one pin reaches the first position, the members connected by the one pin are released from connection with each other. The work machine according to claim 1 .

4. the first pin moves in the removal direction for the first predetermined time period after reaching the first position; The work machine according to claim 1 .

5. the first pin moves in the removal direction for the first predetermined time period after reaching the first position, and reaches a stroke end of the first pin in the removal direction; The work machine according to claim 1 .

6. the first position is a position that is set in advance in relation to the moving speed of the one pin; The work machine according to claim 1 .

7. a detection unit that detects the position of the one pin, the first pin moves in accordance with rotation of the motor in a first rotation direction; the second pin moves in accordance with rotation of the motor in a second rotation direction; The detection unit detecting that the first pin has reached the first position when a rotation angle of the motor in the first rotation direction reaches a first angle; detecting that the second pin has reached the first position when a rotation angle of the motor in the second rotation direction reaches a second angle; The control unit controls the brake mechanism in accordance with the detection result of the detection unit. The work machine according to claim 1 .

Images