Work machine

Abstract

This work machine comprises: an extendable boom that has a plurality of booms and that extends and retracts via an extending and retracting apparatus; first pins that join the booms and the extending and retracting apparatus; second pins that join neighboring booms to each other; a movement mechanism that moves either the first pins or the second pins in a pulling-out direction via a motor, and releases the joining of the fellow members joined by said pins; a brake mechanism that brakes the motor; and a control unit that controls the movement mechanism. When moving said pins, the control unit turns the brake mechanism to an ON state after a first prescribed amount of time has passed from the pins arriving at a first position set in advance.

Description

Work equipment

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

[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 has been 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 (i.e., 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.

[0005] JP 2012-96928 A

[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. For such cranes, there is a need for 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.

[0009] One aspect of the work machine according to the present invention comprises: a telescopic boom having a plurality of booms that is extended and retracted by an extension device; a first pin connecting the boom and the extension device; a second pin connecting adjacent booms; a movement mechanism that moves one of the first and second pins in the extraction direction using a motor to release the connection between the members connected by the one pin; a brake mechanism that brakes the motor; and a control unit that controls the movement mechanism, wherein when one of the pins moves, the control unit turns the brake mechanism on after a first predetermined time has elapsed since the one pin reaches a preset first position.

[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.

[0011] FIG. 1 is a schematic diagram of a mobile crane according to an embodiment of the present invention. FIG. 2A is a schematic diagram illustrating the structure and telescopic operation of a telescopic boom. FIG. 2B is a schematic diagram illustrating the structure and telescopic operation of a telescopic boom. FIG. 2C is a schematic diagram illustrating the structure and telescopic operation of a telescopic boom. FIG. 2D is a schematic diagram illustrating the structure and telescopic operation of a telescopic boom. FIG. 2E is a schematic diagram illustrating the structure and telescopic operation of a telescopic boom. FIG. 3A is a schematic diagram illustrating the operation of a cylinder coupling mechanism. FIG. 3B is a schematic diagram illustrating the operation of a cylinder coupling mechanism. FIG. 3C is a schematic diagram illustrating the operation of a cylinder coupling mechanism. FIG. 4A is a schematic diagram illustrating the operation of a boom coupling mechanism. FIG. 4B is a schematic diagram illustrating the operation of a boom coupling mechanism. FIG. 4C is a schematic diagram illustrating the operation of a boom coupling mechanism. FIG. 5A is a diagram illustrating a detection area of ​​a position information detection device. FIG. 5B is a schematic diagram illustrating the positional relationship between the detection area of ​​the position information detection device and a cylinder coupling pin. Fig. 5C is a schematic diagram showing the positional relationship between the detection area of ​​the position information detection device and the boom connecting pin. Fig. 6 is an enlarged schematic diagram of the cylinder connecting pin and the cylinder pin receiving portion. Fig. 7 is an enlarged schematic diagram of the boom connecting pin and the boom pin receiving portion. Fig. 8 is a flowchart showing the brake control process.

[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 a plurality of booms combined so as to be extendable and retractable. 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 running 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 mounted 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 and extending. 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 provided at 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 telescopically. Specifically, the multiple booms are, from the inside out, 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 to transition from the retracted 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 receivers 141b are provided coaxially around the cylinder pin receivers 1411 and 1412. The boom pin receivers 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 receivers 141b and the pair of cylinder pin receivers 1411 and 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 toward the base end of the boom connecting pin 144a) based on the operation of the 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 receivers 142d are provided coaxially with each other and closer to the base end than the pair of first boom pin receivers 142b. A pair of boom connecting pins 144b are inserted into the pair of third boom pin receivers 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 Figures 2A to 4C, the actuator 2 has a telescopic cylinder 3 and a pin moving mechanism 4. The actuator 2 is located in the internal space of the boom tip 141 when the telescopic boom 14 is in the retracted state (the state shown in Figure 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 (described later).

[0038] The pin moving mechanism 4 corresponds to 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 of the components constituting the actuator 2 will be described based on the state in which each component is assembled 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 corresponds to an example of a movable part of an actuator.

[0041] Such a trunnion unitizes the above-described 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 that 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 the 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 the cylinder connecting mechanism 45 and the 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, when the cylinder coupling mechanism 45 transitions from the expanded state to the contracted state, the rotation direction of the switch gear 471 (arrow A in FIGS. 3A to 3C) １ 3A to 3C ) is defined as a first rotation direction of the switch gear 471. Also, the rotation direction of the switch gear 471 (the direction indicated by the arrow A in FIGS. 3A to 3C ) when the cylinder coupling mechanism 45 transitions from the contracted state to the expanded state is defined as a second rotation direction of the switch gear 471. ２ The direction indicated by the arrow (the direction indicated by the arrow) is defined as a second rotation direction of the switch gear 471.

[0053] The first rotation direction A of the switch gear 471 １ is also the rotation direction of the switch gear 471 when the boom linkage mechanism 46 transitions from the contracted state (see FIG. 4C) to the extended state (see FIG. 4A). ２ is also the rotation direction of the switch gear 471 when the boom linkage mechanism 46 transitions from the extended state (see FIG. 4A) to the retracted state (see FIG. 4C).

[0054] The position information detection device 48 is also 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 (rear side) of the telescopic boom 14. The operation of the cylinder coupling mechanism 45 transitioning from the extended state to the retracted state is the extraction operation of the cylinder coupling mechanism 45. The operation of the cylinder coupling mechanism 45 transitioning from the retracted state to the extended state is the engagement operation of the cylinder coupling 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 tip boom 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 has 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 the 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, the switch gear 471 rotates in the first rotation direction A １ When the switch gear 471 rotates in the first rotation direction A, the first rack teeth of the first rack bar 451 mesh with the teeth of the switch gear 471. １ When the switch gear 471 is further rotated, 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. The second gear mechanism 453 also meshes 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. These cylinder connecting pins 454A, 454B are supported by trunnions (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] The first biasing mechanism 455 returns the cylinder connecting mechanism 45 to the expanded state 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 Figure 3C).

[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 to the tip end 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 that connects adjacent booms to each other 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 (e.g., a pair of boom connection pins 144a). The boom connection mechanism 46 disengages the boom connection pin from the boom by transitioning from the extended state to the retracted state while engaged with the boom connection pin.

[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 461 a and 461 b, a synchronization gear 462 , and a second biasing mechanism 463 .

[0078] The pair of second rack bars 461 a, 461 b 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. Each of the pair of second rack bars 461 a, 461 b is arranged above the first rack bar 451 of the cylinder linkage mechanism 45.

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

[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 pin (e.g., 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, the 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] From the expanded state of the boom connection mechanism 46, the switch gear 471 of the switching mechanism 47 is rotated in the second rotation direction A ２ When the switch gear 471 rotates in the second rotation direction A, the rack teeth of the second rack bar 461a on one side mesh with the teeth of the switch gear 471. From this state, the switch gear 471 rotates in the second rotation direction A. ２ When the switch gear 471 is further rotated, one of the second rack bars 461 a moves in its axial direction in response to the rotation of the switch gear 471 .

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

[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 461 a, 461 b in directions away from each other.

[0085] In other words, when the boom connection mechanism 46 is in the contracted state, the second biasing mechanism 463 returns the boom connection 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 configured by a pair of coil springs 463 a, 463 b. The pair of coil springs 463 a, 463 b bias the base ends of the pair of second rack bars 461 a, 461 b 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 detected body may be provided on a member that rotates together with the output shaft of the electric motor 41. Therefore, the detected body 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, i.e., the sensor outputs a voltage corresponding to the rotation angle of the transmission shaft 432 to which the object to be detected is fixed (i.e., the rotation angle of the electric motor 41).

[0091] The position information detection 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 detection 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 position (in other words, the state) 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] The dashed line L in FIGS. 5A to 5C １ indicates the position where the rotation angle of the electric motor 41 is 0° (hereinafter referred to as the reference position). １ This also indicates a 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 refers to the angle by which the output shaft of the electric motor 41 has rotated 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] When the electric motor 41 is in the reference state, the cylinder coupling mechanism 45 is in the extended state shown in Fig. 3A. When the electric motor 41 is in the reference state, the cylinder coupling pins 454A and 454B are in the engaged state.

[0097] In the reference state of the electric motor 41, the cylinder connecting pins 454A and 454B are aligned with the cylinder connecting pin CP in FIG. １ Located at the position.

[0098] In addition, in FIG. 5B, the cylinder connecting pin CP １ ~CP ４ When the cylinder coupling mechanism 45 transitions from the expanded state to the contracted state, the cylinder coupling pins 454A and 454B are connected to the cylinder coupling pin CP １ From the state of the cylinder connecting pin CP ２ , C.P. ３ Through this state, the cylinder connecting pin CP ４ The state changes to

[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] In the standard state of the electric motor 41, the boom connecting pin 144a is connected to the boom connecting pin BP in FIG.１ Located at the position.

[0101] In addition, in FIG. 5C, the boom connecting pin BP １ ~BP ４ When the boom connection mechanism 46 transitions from the extended state to the retracted state while being engaged with the boom connection pin 144a, the boom connection pin 144a engages with the boom connection pin BP １ From the state of the boom connecting pin BP ２ , B.P. ３ Through this state, the boom connecting pin BP ４ The state changes to

[0102] The electric motor 41 rotates in a first rotation direction A from the reference position. １ When the electric motor 41 rotates in the second rotation direction A from the reference position, the cylinder coupling mechanism 45 is actuated. ２ When the boom 44 rotates in the first rotation direction A from the reference position, the boom connecting mechanism 46 is actuated. １ On the other hand, the angle on the side of the second rotation direction A from the reference position is expressed as a negative angle. ２ The side is represented by a positive angle.

[0103] The position information detection device 48 detects information regarding 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, referring to FIGS. 5A and 5B, the electric motor 41 rotates in a first rotation direction A from the reference position. １ When the electric motor 41 rotates in the first rotation direction A from the reference position, the following description will be given. １ When the cylinder coupling mechanism 45 is rotated in this manner, the cylinder coupling mechanism 45 transitions from the expanded state to the contracted state. Such an operation of the cylinder coupling mechanism 45 is controlled by the control unit 50 (see FIGS. 3A to 3C).

[0105] Hereinafter, the control by the control unit 50 to transition the cylinder connecting mechanism 45 from the expanded state to the contracted state will be referred to as cylinder connecting pin removal control. １(see FIGS. 5A and 5B), it is determined that the cylinder connecting pins 454A, 454B are in the engaged state.

[0106] First detection region R １ is a first predetermined angle θ from the reference position １ (See FIGS. 5A and 5B). １ may be, for example, −20°. １ In this case, the cylinder connecting pins 454A and 454B are the cylinder connecting pins CP in FIG. ２ Located at the position.

[0107] In the control of removing the cylinder connecting pins, the cylinder connecting pins 454A and 454B are moved in the direction of arrow A shown in FIG. ３ The arrow A shown in FIG. ３ This direction is referred to as the cylinder connecting pin removal direction.

[0108] In addition, in the removal control of the cylinder connecting pin, the position information detection device 48 detects when the detection angle is within the second detection region R ２ (see FIGS. 5A and 5B), it is determined that the cylinder connecting pins 454A, 454B are in the intermediate state.

[0109] Second detection region R ２ is the first predetermined angle θ １ from the second predetermined angle θ ２ (See FIGS. 5A and 5B). ２ The second predetermined angle θ may be, for example, −65°. ２ is an example of the first angle.

[0110] The detected angle of the position information detection device 48 is the second predetermined angle θ ２ In this case, the cylinder connecting pins 454A and 454B are the cylinder connecting pins CP in FIG. ３ Located at the position.

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

[0112] The detected angle of the position information detection device 48 is the second predetermined angle θ ２ In this case, as shown in FIGS. 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] In addition, the detected angle of the position information detection device 48 is the second predetermined angle θ ２ In this case, the positions of the tip surfaces 454a of the cylinder connecting pins 454A and 454B may be slightly shifted in the left-right direction in FIG. 6 from the state shown in FIG.

[0114] The cylinder connecting pin CP shown in FIG. ３ and the positions of the cylinder connecting pins 454A, 454B shown in Figure 6 correspond to an example of the first position of the cylinder connecting pins. 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] Thus, 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 contact between the cylinder connecting pins 454A, 454B and the cylinder pin receivers 1411, 1412.

[0116] Furthermore, the position information detection device 48 detects the position of the object when the detection angle is within the third detection area R ３ If the third detection region R is within the third detection region R (see FIGS. 5A and 5B), it is determined that the cylinder connecting pins 454A and 454B are in the removed state. ３ is the second predetermined angle θ ２ from the third predetermined angle θ ３ (See FIGS. 5A and 5B.) The third predetermined angle may be, for example, −95°.

[0117] The cylinder connecting pins 454A and 454B move a predetermined distance in the removal direction during the removal control of the cylinder connecting pins. This predetermined distance is referred to as the stroke amount S of the cylinder connecting pins. １(See FIG. 5B). The moving speed of the cylinder connecting pin during the removal control of the cylinder connecting pin is the first predetermined speed. That is, during the removal control of the cylinder connecting pin, the cylinder connecting pin moves at a stroke amount S １ is moved at a first predetermined speed.

[0118] Cylinder connecting pin CP in FIG. ４ The position of the connecting pin is the stroke end in the direction in which the connecting pin is pulled out (hereinafter referred to as the stroke end). When the connecting pin is positioned at the stroke end, the rotation angle of the electric motor 41 is equal to the second predetermined angle θ ２ and a third predetermined angle θ ３ is the angle between

[0119] In this embodiment, the position information detection device 48 detects whether the cylinder connecting pins 454A and 454B are the cylinder connecting pins CP in FIG. ４ Therefore, it is not possible to accurately identify (in other words, detect) the rotation angle of the electric motor 41 when it is positioned at the position (i.e., the stroke end).

[0120] Next, referring to FIGS. 5A and 5C, the electric motor 41 rotates in the second rotation direction A from the reference position. ２ 5A and 5C, the case where the electric motor 41 rotates in the second rotation direction A from the reference position will be described. ２ When the boom connecting mechanism 46 rotates in this direction, the boom connecting mechanism 46 transitions from the extended state to the retracted state. Such operation of the boom connecting mechanism 46 is controlled by the control unit 50 (see FIGS. 4A to 4C).

[0121] Hereinafter, the control by the control unit 50 to transition the boom connection mechanism 46 from the extended state to the retracted state will be referred to as boom connection pin removal control. In the boom connection pin removal control, the position information detection device 48 detects when the detection angle falls within the fourth detection region R ４ (see FIGS. 5A and 5C), it is determined that the boom connecting pin 144a is in the engaged state.

[0122] Fourth detection region R ４ is a fourth predetermined angle θ from the reference position ４ (See FIGS. 5A and 5C). ４may be, for example, 10°. ４ In this case, the boom connecting pin 144a is the boom connecting pin BP in FIG. ２ Located at the position.

[0123] In the control of removing the boom connecting pin, the boom connecting pin 144a is moved in the direction of arrow A shown in FIG. ４ (See FIGS. 5A and 5C). ４ The direction of is called the boom connecting pin removal direction.

[0124] In addition, in the removal control of the boom connecting pin, the position information detection device 48 detects when the detection angle is within the fifth detection area R ５ (see FIGS. 5A and 5C ), it is determined that the boom connecting pin 144a is in the intermediate state. ５ is the fourth predetermined angle θ ４ to the fifth predetermined angle θ ５ (See FIGS. 5A and 5C). ５ The fifth predetermined angle θ may be, for example, 65°. ５ is an example of the second angle.

[0125] The rotation angle of the electric motor 41 is the fifth predetermined angle θ ５ In this case, the boom connecting pin 144a is the boom connecting pin BP in FIG. ３ Located at the position.

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

[0127] The detected angle of the position information detection device 48 is the fifth predetermined angle θ ５ In this case, as shown in Figure 7, the tip end surface 144c of the boom connecting pin 144a and the inner end surface 142e of the first boom pin receiving portion 142b are positioned on the same plane. ５ In this case, the position of the tip end 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.

[0128] The boom connecting pin BP shown in FIG. ３ and the position of the boom connecting pin 144a shown in Figure 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 boom connecting pin 144a releases the connection between adjacent booms.

[0129] The first position of the boom connecting pin is the theoretical (or designed) position at which adjacent booms are released from connection with each other. 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 detection device 48 detects the position of the object when the detection angle is within the sixth detection area R ６ (see FIGS. 5A and 5C ), it is determined that the boom connecting pin 144 a is in the removed state. ６ is the fifth predetermined angle θ ５ to the sixth predetermined angle θ ６ (See FIGS. 5A and 5C). ６ may be, for example, 95°.

[0131] The boom connecting pin 144a moves a predetermined distance in the extraction direction during the extraction control of the boom connecting pin. This predetermined distance is referred to as the stroke amount S of the boom connecting pin. ２ (See FIGS. 5A and 5C). The moving speed of the boom connecting pin during the removal control of the boom connecting pin is the second predetermined speed. That is, during the removal control of the boom connecting pin, the boom connecting pin moves at a stroke amount S ２ at a second predetermined speed.

[0132] Boom connecting pin BP in FIG. ４ The position of the boom connecting pin is the stroke end in the direction in which the boom connecting pin is pulled out (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 equal to the fifth predetermined angle θ ５ and a sixth predetermined angle θ ６ is the angle between

[0133] In this embodiment, the position information detection device 48 detects whether the boom connecting pin 144a is the boom connecting pin BP４ Therefore, it is not possible to accurately identify (in other words, detect) the rotation angle of the electric motor 41 when the electric motor 41 is positioned at 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] 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 the cylinder connecting mechanism 45 in a contracted state and the pair of cylinder connecting pins 454A, 454B and the pair of cylinder pin receiving portions 1411, 1412 of the tip boom 141 in a disengaged state.

[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 in such a way that a CPU, ROM, RAM, HDD, etc. are connected via a bus, or may be configured as a one-chip LSI, etc.

[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 (arrow A in FIG. 3A ) based on the power of the electric motor 41. １ (the direction indicated by the arrow).

[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 linking mechanism 45 is restricted. In other words, the cylinder linking mechanism 45 is maintained in a contracted state. That is, the positions of the pair of cylinder linking pins 454A, 454B are maintained. After that, 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 described above 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 471 rotates in the second rotation direction (arrow A in FIG. 4A ) based on the power of the electric motor 41. ２ 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, the switch gear 471 rotates in the second rotation direction A ２ 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 obtained 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 during the removal control of the cylinder connecting pin and the removal control of the boom connecting pin. The brake control during the removal control of the boom connecting pin is substantially the same as the brake control during 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. Brake control during removal control of the cylinder connecting pins will now 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 48.

[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 equal to or greater than the second predetermined angle θ based on the information about the positions of the cylinder connecting pins 454A and 454B acquired in step S1. ２ (See FIGS. 5A and 5B).

[0168] The rotation angle of the electric motor 41 (in other words, the transmission shaft 432) is set to a second predetermined angle θ ２ In this case, the cylinder connecting pins 454A and 454B are the cylinder connecting pins CP shown in FIG. ３ and the positions of the cylinder connecting pins 454A and 454B shown in FIG.

[0169] In this example, the cylinder connecting pin CP shown in FIG. ３ and the position 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 movement 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 proceeds 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 control unit 50 determines in step S3 that the first predetermined time has not elapsed since the cylinder connecting pins 454A, 454B reached the first position ("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 proceeds 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, thereby enabling the telescopic boom 14 to be extended and retracted efficiently.

[0178] The stroke end of the cylinder connecting pins 454A and 454B in the drawing direction is the cylinder connecting pin CP shown in FIG. ４ In this state, the cylinder coupling mechanism 45 is in the 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 of the cylinder connecting pins 454A, 454B with 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] In other words, 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 movement 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 on the brake mechanism 42. 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 the present embodiment, as described above, the position information detection device 48 detects whether the cylinder connecting pins 454A and 454B are the cylinder connecting pins CP in FIG. ４ Therefore, it is not possible to accurately identify (in other words, detect) the rotation angle of the electric motor 41 when it is positioned at the position (i.e., the stroke end).

[0184] On the other hand, the position information detection device 48 detects whether the cylinder connecting pins 454A and 454B are aligned with the cylinder connecting pin CP in FIG. ３Therefore, the rotation angle of the electric motor 41 when the electric motor 41 is in the position (i.e., the first position) can be accurately specified (in other words, detected).

[0185] In this embodiment, the timing for turning 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] (Functions and Effects of the Present Embodiment) The mobile crane 1 according to the present embodiment 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 the 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 the present embodiment are as described above.

[0192] <Note> The technical idea disclosed in the specification and drawings includes inventions obtained by arbitrarily combining the various configurations described in the above-mentioned embodiments. In particular, the technical idea disclosed in the specification and drawings includes inventions obtained by arbitrarily applying the various configurations disclosed in the specification and drawings to the above-mentioned basic configuration.

[0193] The disclosures of the specification, drawings, and abstract contained in Japanese Patent Application No. 2024-102203, filed on June 25, 2024, are incorporated herein by reference in their entirety.

[0194] 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 telescoping boom.

[0195] 1 Mobile crane 10 Traveling body 12 Swivel base 14 Telescopic boom 141 Tip boom 1411, 1412 Cylinder pin receiving portion 1413 Inner end surface 141b Boom pin receiving portion 142 Intermediate boom 142a Cylinder pin receiving portion 142b First boom pin receiving portion 142c Second boom pin receiving portion 142d Third boom pin receiving portion 142e Inner end surface 143 Base boom 144a, 144b, BP １ , B.P. ２ , B.P. ３ , B.P. ４Boom connecting pin 144c Tip surface 16 Wire rope 17 Hook 2 Actuator 3 Telescopic cylinder 31 Rod member 32 Cylinder member 4 Pin moving mechanism 41 Electric motor 42 Brake mechanism 43 Transmission mechanism 431 Reducer 432 Transmission shaft 45 Cylinder connecting mechanism 451 First rack bar 452 First gear mechanism 453 Second gear mechanism 454A, 454B, CP １ , C.P. ２ , C.P. ３ , C.P. ４ Cylinder connecting pin 454a Tip surface 455 First biasing mechanism 455a, 455b Coil spring 46 Boom connecting mechanism 461a, 461b Second rack bar 462 Synchronous gear 463 Second biasing mechanism 463a, 463b Coil spring 47 Switching mechanism 471 Switch gear 48 Position information detecting device 50 Control unit

Claims

1. A work machine comprising: a telescopic boom having multiple booms that extend and retract using a telescopic device; a first pin that connects the booms to the telescopic device; a second pin that connects adjacent booms together; a movement mechanism that uses a motor to move one of the first and second pins in the extraction direction to release the connection between the members connected by the one pin; a brake mechanism that brakes the motor; and a control unit that controls the movement mechanism, wherein the control unit turns on the brake mechanism when the one pin moves and a first predetermined time has elapsed since the one pin reaches a predetermined first position.

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

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

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

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

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

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

Images