Work machine

Abstract

This work machine comprises: a telescopic boom that has a plurality of booms and expands and contracts by a telescopic cylinder; a first connection mechanism that connects the boom and the telescopic cylinder and releases the connection with a motor; a second connection mechanism that connects the adjacent booms and releases the connection with the motor; and a switching mechanism that moves in the axial direction, is selectively connected to one of the first connection mechanism and the second connection mechanism, and has a motor side transmission member that transmits power of the motor to one of the connection mechanisms.

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 that includes a telescopic boom in which multiple booms are nested one on top of the other, and a hydraulic actuator (telescopic cylinder) that extends the telescopic boom.

[0003] Adjacent booms are connected to each other by a boom connecting 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 actuator is connected to the movable boom via a cylinder connecting pin. When the actuator moves in the extension / retraction direction, the movable boom moves together with the actuator, and the telescopic boom extends or retracts.

[0005] JP 2012-96928 A

[0006] The crane described above includes a hydraulic actuator for displacing the boom connecting pin, a hydraulic actuator for displacing the cylinder connecting pin, and a hydraulic circuit for supplying pressure oil to each of these actuators. Such hydraulic circuits are provided, for example, around the telescopic boom. This can reduce the degree of freedom in designing the area around the telescopic boom.

[0007] An object of the present invention is to provide a crane that can improve the degree of freedom in design around the telescopic boom.

[0008] One aspect of the work machine according to the present invention comprises: a telescopic boom having a plurality of booms that are extended and retracted by a telescopic cylinder; a first connecting mechanism that connects the booms to the telescopic cylinders and releases the connection by a motor; a second connecting mechanism that connects adjacent booms to each other and releases the connection by a motor; and a switching mechanism having a motor-side transmission member that moves axially to be selectively connected to one of the first and second connecting mechanisms and transmits power from the motor to one of the connecting mechanisms.

[0009] According to the present invention, it is possible to provide a work machine that can improve the degree of freedom in design around the telescopic boom.

[0010] FIG. 1 is a schematic diagram of a mobile crane according to a first 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 schematic diagram illustrating a switching mechanism. FIG. 5B is a schematic diagram illustrating a switching mechanism. FIG. 6A is a schematic diagram illustrating a switching mechanism. FIG. 6B is a schematic diagram showing a switching mechanism. FIG. 7A is a diagram showing a switching mechanism according to a second embodiment of the present invention. FIG. 7B is a diagram showing a switching mechanism according to the second embodiment of the present invention. FIG. 7C is a diagram showing a switching mechanism according to the second embodiment of the present invention. FIG. 8A is a diagram showing a switching mechanism according to a third embodiment of the present invention. FIG. 8B is a diagram showing a switching mechanism according to the third embodiment of the present invention. FIG. 9A is a diagram showing a switching mechanism according to a fourth embodiment of the present invention. FIG. 9B is a diagram showing a switching mechanism according to the fourth embodiment of the present invention. FIG. 10 is a diagram showing a switching mechanism according to a fifth embodiment of the present invention. FIG. 11 is a diagram showing an example of a modification of the switching mechanism according to the fifth embodiment. FIG. 12A is a diagram showing a switching mechanism according to a sixth embodiment of the present invention. FIG. 12B is a diagram showing a switching mechanism according to the sixth embodiment of the present invention. FIG. 13A is a diagram showing a switching mechanism according to a seventh embodiment of the present invention. FIG. 13B is a diagram showing a switching mechanism according to the seventh embodiment of the present invention.

[0011] 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.

[0012] 1 to 6B, a mobile crane 1 according to a first embodiment of the present invention will be described. First, an overview of the mobile crane 1 according to the first embodiment of the present invention will be described with reference to Fig. 1 and Fig. 2A to Fig. 2E.

[0013] 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.

[0014] 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).

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The cylinder connecting pins 454A, 454B are each 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).

[0024] 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.

[0025] 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, the illustration shows the pair of boom pin receivers 141b and the pair of cylinder pin receivers 1411 and 1412 as being offset in the axial direction of the telescopic boom 14. In reality, the pair of boom pin receivers 141b and the pair of cylinder pin receivers 1411 and 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.

[0026] Each of the pair of boom connecting pins 144a 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, which will be described later. 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, which will be described later.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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. For ease of explanation, in the drawings, the pair of first boom pin receiving portions 142b and the pair of cylinder pin receiving portions 142a are shown 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.

[0031] 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.

[0032] 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.

[0033] 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).

[0034] The telescopic cylinder 3 has 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).

[0035] The pin moving mechanism 4 has an electric motor 41, a brake mechanism 42, a transmission mechanism 43, a position information detection device 44, a switching mechanism 5, a cylinder connecting mechanism 45, and a boom connecting mechanism 46, all of which are supported by a trunnion (not shown).

[0036] 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.

[0037] 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.

[0038] Such a trunnion unitizes the above elements 41 to 46. Such a configuration contributes to the miniaturization of the pin moving mechanism 4, improvement of productivity, and improvement of the reliability of the system.

[0039] 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.

[0040] The brake mechanism 42 applies a braking force to the electric motor 41. When the electric motor 41 is stopped, the brake mechanism 42 prevents the rotation of the output shaft of the electric motor 41. This maintains the state of the pin moving mechanism 4 when the electric motor 41 is stopped.

[0041] 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 44 (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.

[0042] The position information detection device 44 is also connected to a control unit (not shown) 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 44, and the signal transmission cable of the position information detection device 44 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.

[0043] 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 42 may be switched based on an operation by an operator.

[0044] 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.

[0045] The reducer 431 reduces the rotation of the electric motor 41 and transmits the reduced rotation to the transmission shaft 432. The transmission shaft 432 transmits the rotation of the reducer 431 to the switching mechanism 5, which will be described later. In addition, a position information detection device 44 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.

[0046] The information regarding the positions of the cylinder connecting pins 454A, 454B and the pair of boom connecting pins 144a, 144b is, for example, the amount of movement of the cylinder connecting pins 454A, 454B or the pair of boom connecting pins 144a, 144b from a reference position. 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 position of the pair of boom connecting pins 144a shown in Fig. 4A is the reference position of the boom connecting pin 144a.

[0047] The switching mechanism 5 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.

[0048] The configuration of the switching mechanism 5 will be described with reference to Figures 3A to 3C, 4A to 4C, and 5A to 6B. The switching mechanism 5 has a motor-side clutch gear 6, a cylinder-side clutch gear 8, and a boom-side clutch gear 7. The motor-side clutch gear 6, the cylinder-side clutch gear 8, and the boom-side clutch gear 7 are arranged on the same straight line.

[0049] The motor-side clutch gear 6 is an example of a motor-side transmission member, and is connected to the transmission mechanism 43 (specifically, the transmission shaft 432). The motor-side clutch gear 6 rotates based on the power (i.e., rotation) of the electric motor 41 transmitted via the transmission mechanism 43.

[0050] The motor-side clutch gear 6 is movable in the axial direction of the motor-side clutch gear 6. For example, the motor-side clutch gear 6 is moved in the axial direction of the motor-side clutch gear 6 by a clutch actuator (not shown).

[0051] In the following description of the switching mechanism 5, unless otherwise specified, the axial direction refers to the axial direction of the motor-side clutch gear 6. The clutch actuator will be described later in the second embodiment. The clutch actuator in the second embodiment can also be applied to the switching mechanism 5 of this embodiment.

[0052] The motor-side clutch gear 6 has a motor-side first tooth portion 61 at one axial end (also referred to as a first end) and a motor-side second tooth portion 62 at the other axial end (also referred to as a second end).

[0053] The motor-side first tooth portion 61 has a plurality of motor-side first convex portions 611 that are arranged side by side and spaced apart in the circumferential direction. The motor-side first convex portions 611 are convex portions that extend toward the boom-side clutch gear 7, which will be described later. The motor-side first convex portions 611 have a first inclined surface 6111 on the end face that faces the boom-side clutch gear 7.

[0054] The motor-side second tooth portion 62 has a plurality of motor-side second protrusions 622 arranged side by side and spaced apart in the circumferential direction. The motor-side second protrusions 622 are protrusions extending toward the cylinder-side clutch gear 8, which will be described later. The motor-side second protrusions 622 have a second inclined surface 6221 on the end face facing the cylinder-side clutch gear 8.

[0055] The motor-side clutch gear 6 also has a through-hole 63 that axially passes through the motor-side clutch gear 6. The through-hole 63 opens to one end face (also referred to as a first end face) of the motor-side clutch gear 6 in the axial direction, and to the other end face (also referred to as a second end face) of the motor-side clutch gear 6 in the axial direction.

[0056] The boom side clutch gear 7 is an example of a first transmission member, and is connected to the boom connection mechanism 46, which will be described later. Specifically, the boom side clutch gear 7 is connected to the boom connection mechanism 46 via a boom side pinion gear 73 (see FIGS. 3A to 4C ). Note that in FIGS. 3A to 4C , the connection structure of the boom side clutch gear 7, the boom side pinion gear 73, and the boom connection mechanism 46 is shown schematically. The boom side pinion gear 73 may be any of various pinion gears (for example, a bevel gear, a spur gear, or a helical gear). The boom side clutch gear 7 transmits the power of the electric motor 41, which is transmitted from the motor side clutch gear 6, to the boom connection mechanism 46. In addition, in FIGS. 3A to 4C , the connection structure of the transmission shaft 432 and the motor side clutch gear 6 is also shown schematically.

[0057] The boom side clutch gear 7 has a gear body 71 and a shaft portion 72. The boom side clutch gear 7 and the motor side clutch gear 6 are provided on the same straight line.

[0058] The gear body 71 is rotatable and can engage with the motor-side clutch gear 6. The gear body 71 has a boom-side toothed portion 711 at one end (also referred to as a first end) in the axial direction. The boom-side toothed portion 711 is an example of a first toothed portion.

[0059] The boom side tooth portion 711 has a plurality of boom side convex portions 712 that are arranged side by side and spaced apart in the circumferential direction. The boom side convex portions 712 are convex portions that extend toward the motor side clutch gear 6. The boom side convex portions 712 have a boom side inclined surface 7121 on the end face on the motor side clutch gear 6 side.

[0060] The shaft portion 72 is provided integrally with the gear body 71. The shaft portion 72 is provided on the central axis of the gear body 71. The shaft portion 72 extends in the axial direction from the gear body 71 toward the motor-side clutch gear 6.

[0061] The shaft portion 72 is inserted into the through-hole 63 of the motor-side clutch gear 6. The outer diameter of the shaft portion 72 is slightly smaller than the outer diameter of the through-hole 63. Such a shaft portion 72 has the function of guiding the movement of the motor-side clutch gear 6 in the axial direction.

[0062] The shaft portion 72 also has the function of positioning the motor-side clutch gear 6 and the boom-side clutch gear 7. Such a shaft portion 72 contributes to improving the coaxiality between the motor-side clutch gear 6 and the boom-side clutch gear 7.

[0063] A boom side pinion gear 73 is fixed to the gear body 71. The boom side pinion gear 73 transmits the rotation of the gear body 71 to the boom connection mechanism 46. The boom side pinion gear 73 may be provided integrally with the gear body 71.

[0064] The boom-side pinion gear 73 is engaged with the boom connecting mechanism 46 (specifically, the second rack bar 461a).

[0065] The cylinder side clutch gear 8 is an example of a second transmission member, and is connected to the cylinder coupling mechanism 45, which will be described later. Specifically, the cylinder side clutch gear 8 is connected to the cylinder coupling mechanism 45 via a cylinder side pinion gear 83 (see FIGS. 3A to 4C ). Note that in FIGS. 3A to 4C , the coupling structure of the cylinder side clutch gear 8, the cylinder side pinion gear 83, and the cylinder coupling mechanism 45 is shown schematically. The cylinder side pinion gear 83 may be any of various pinion gears (for example, a bevel gear, a spur gear, or a helical gear). The cylinder side clutch gear 8 transmits the power of the electric motor 41, which is transmitted from the motor side clutch gear 6, to the cylinder coupling mechanism 45.

[0066] The cylinder side clutch gear 8 has a gear body 81 and a shaft portion 82. The cylinder side clutch gear 8 and the motor side clutch gear 6 are provided on the same straight line.

[0067] The gear body 81 is rotatable and can engage with the motor-side clutch gear 6. The gear body 81 has a cylinder-side toothed portion 811 at one axial end (also referred to as a first end) of the gear body 81. The cylinder-side toothed portion 811 is an example of a second toothed portion.

[0068] The cylinder side tooth portion 811 has a plurality of cylinder side protrusions 812 arranged side by side and spaced apart in the circumferential direction. The cylinder side protrusions 812 are protrusions that extend toward the motor side clutch gear 6. The cylinder side protrusions 812 have a cylinder side inclined surface 8121 on the end face on the motor side clutch gear 6 side.

[0069] The shaft portion 82 is provided integrally with the gear body 81. The shaft portion 82 is provided on the central axis of the gear body 81. The shaft portion 82 extends in the axial direction from the gear body 81 toward the motor-side clutch gear 6.

[0070] The shaft portion 82 is inserted into the through-hole 63 of the motor-side clutch gear 6. The outer diameter of the shaft portion 82 is slightly smaller than the outer diameter of the through-hole 63. Such a shaft portion 82 has the function of guiding the movement of the motor-side clutch gear 6 in the axial direction.

[0071] The shaft portion 82 also has the function of positioning the motor-side clutch gear 6 and the cylinder-side clutch gear 8. Such a shaft portion 82 contributes to improving the coaxiality between the motor-side clutch gear 6 and the cylinder-side clutch gear 8.

[0072] A cylinder side pinion gear 83 is fixed to the gear body 81. The cylinder side pinion gear 83 is a member that transmits the rotation of the gear body 81 to the cylinder linking mechanism 45. The cylinder side pinion gear 83 may be provided integrally with the gear body 81.

[0073] The cylinder-side pinion gear 83 is engaged with the cylinder coupling mechanism 45 (specifically, the first rack bar 451). The operation of the switching mechanism 5 having the above-described configuration will be described later.

[0074] 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).

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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 .

[0079] The first rack bar 451 moves in its axial direction in response to power (specifically, rotation) transmitted from the switching mechanism 5 (specifically, the cylinder-side clutch gear 8). The first rack bar 451 is located at the first position when the cylinder coupling mechanism 45 is in the expanded state (see FIG. 3A).

[0080] On the other hand, the first rack bar 451 is located at the second position when the cylinder coupling mechanism 45 is in the contracted state (see FIG. 3C ). That is, the first rack bar 451 moves between the first position and the second position. The first rack bar 451 is connected to the cylinder-side clutch gear 8 of the switching mechanism 5 via the cylinder-side pinion gear 83.

[0081] In the expanded state, when the cylinder side clutch gear 8 rotates a predetermined amount, the first rack bar 451 moves in accordance with the rotation of the cylinder side clutch gear 8 .

[0082] 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).

[0083] 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.

[0084] 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.

[0085] 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.

[0086] When the electric motor 41 is de-energized while the cylinder coupling mechanism 45 is in the contracted state (see FIG. 3C), the first biasing mechanism 455 returns the cylinder coupling mechanism 45 to the expanded state.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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 .

[0097] 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.

[0098] 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.

[0099] The pair of second rack bars 461a, 461b have locking claws 461g, 461h at their tips, respectively. The locking claws 461g, 461h engage with the boom connecting pins (e.g., boom connecting pins 144a, 144b) when the boom connecting pins are moved.

[0100] One second rack bar 461a moves in its axial direction in response to power (specifically, rotation) transmitted from the switching mechanism 5 (specifically, the boom side clutch gear 7) via the boom side pinion gear 73. One second rack bar 461a is located at a first position when the boom connection mechanism 46 is in the extended state. On the other hand, one second rack bar 461a is located at a second position when the boom connection mechanism 46 is in the retracted state. In other words, one second rack bar 461a moves between the first position and the second position.

[0101] When the boom side clutch gear 7 of the switching mechanism 5 rotates a predetermined amount from the extended state of the boom connecting mechanism 46, one of the second rack bars 461a moves in its axial direction in accordance with the rotation of the boom side clutch gear 7.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] <Operation of Coupling Mechanism> Hereinafter, an example of the operation of the switching mechanism 5, the cylinder coupling mechanism 45, and the boom coupling mechanism 46 will be described with reference to FIGS. 3A to 6A.

[0106] Next, an example of the operation of the switching mechanism 5 and the boom connecting mechanism 46 will be described with reference to FIGS. 4A to 4C, 5A, and 5B.

[0107] The boom connection mechanism 46 transitions from the extended state to the retracted state based on the power of the electric motor 41. This operation is referred to as the retracting operation of the boom connection mechanism 46. This operation is also referred to as the retracting operation of the boom connection mechanism 46.

[0108] In the removal operation of the boom connection mechanism 46, the pair of boom connection pins 144a are removed from, for example, the pair of first boom pin receivers 142b of the intermediate boom 142. This releases the connection between the tip boom 141 and the intermediate boom 142. Below, we will explain the operation of the boom connection mechanism 46 when the pair of boom connection pins 144a are the target.

[0109] Before the boom connection mechanism 46 performs the retracting operation, the switching mechanism 5 is in the state shown in Fig. 5A. The state shown in Fig. 5A is referred to as the neutral state, non-connected state, or initial state of the switching mechanism 5. In addition, the position of the motor-side clutch gear 6 in the state of the switching mechanism 5 shown in Fig. 5A is referred to as the third position.

[0110] When the switching mechanism 5 is in the state shown in Figure 5A, the states of the members of the pin moving mechanism 4 are as follows: Boom connection mechanism 46: extended state Cylinder connection mechanism 45: extended state Boom connection pin 144a: engaged state Cylinder connection pins 454A, 454B: engaged state Electric motor 41: OFF Brake mechanism 42: OFF Switching mechanism 5: neutral state

[0111] When the boom connection mechanism 46 performs the operation of extracting the boom connection mechanism 46, the motor-side clutch gear 6 moves from the neutral state toward the boom-side clutch gear 7. The moving direction of the motor-side clutch gear 6 at this time is also referred to as a first direction (the direction of arrow A1 in FIG. 5A ). The first direction is one side of the motor-side clutch gear 6 in the axial direction.

[0112] Specifically, the control unit (not shown) drives the clutch actuator (not shown) to move the motor-side clutch gear 6 in the first direction. At this time, the electric motor 41 is in the OFF state. Therefore, the motor-side clutch gear 6 does not rotate.

[0113] The switching mechanism 5 then assumes the state shown in Fig. 5B. The state shown in Fig. 5B is referred to as the first coupled state of the switching mechanism 5. In the first coupled state of the switching mechanism 5, the motor-side clutch gear 6 engages with the boom-side clutch gear 7. Furthermore, the position of the motor-side clutch gear 6 in the state of the switching mechanism 5 shown in Fig. 5B is referred to as the first position.

[0114] Specifically, the motor-side first tooth portion 61 of the motor-side clutch gear 6 engages with the boom-side tooth portion 711 of the boom-side clutch gear 7. When the switching mechanism 5 enters the first connected state, the clutch actuator (not shown) stops. At this time, it is preferable that the motor-side clutch gear 6 is biased toward the boom-side clutch gear 7.

[0115] The first coupled state of the switching mechanism 5 is a state in which rotation of the motor-side clutch gear 6 can be transmitted to the boom-side clutch gear 7. In the first coupled state of the switching mechanism 5, the motor-side first convex portion 611 of the motor-side first tooth portion 61 of the motor-side clutch gear 6 and the boom-side convex portion 712 of the boom-side tooth portion 711 of the boom-side clutch gear 7 are engaged in the circumferential direction.

[0116] Furthermore, in the first connected state of the switching mechanism 5, the first inclined surface 6111 of the motor side clutch gear 6 and the boom side inclined surface 7121 of the boom side clutch gear 7 engage (specifically, abut) while facing each other in the axial direction.

[0117] When the switching mechanism 5 is in the state shown in Figure 5B, the states of the members of the pin moving mechanism 4 are as follows: Boom connection mechanism 46: extended state Cylinder connection mechanism 45: extended state Boom connection pin 144a: engaged state Cylinder connection pins 454A, 454B: engaged state Electric motor 41: OFF Brake mechanism 42: OFF Switching mechanism 5: first connected state

[0118] 5B, the control unit (not shown) turns on the electric motor 41. Then, the control unit drives the electric motor 41 in a first rotation direction. The power (rotation) of the electric motor 41 is transmitted to the motor-side clutch gear 6 via the transmission mechanism 43.

[0119] 5B. The rotation direction of the motor-side clutch gear 6 at this time is referred to as a first rotation direction of the motor-side clutch gear 6.

[0120] The power (rotation) of the electric motor 41 is transmitted from the motor-side clutch gear 6 to the boom-side clutch gear 7 by the motor-side first convex portion 611 of the motor-side clutch gear 6 pushing the boom-side convex portion 712 of the boom-side clutch gear 7 in the circumferential direction (i.e., the first rotation direction).

[0121] As described above, when the motor-side clutch gear 6 rotates, the boom-side clutch gear 7 engaged with the motor-side clutch gear 6 also rotates. The rotation of the boom-side clutch gear 7 is then transmitted to the boom connection mechanism 46 (specifically, the second rack bar 461a) via the boom-side pinion gear 73.

[0122] As a result, the boom connection mechanism 46 transitions from the extended state (see FIG. 4A) to the retracted state (see FIG. 4C). Specifically, the power transmitted from the boom-side clutch gear 7 to the second rack bar 461a is transmitted to the pair of boom connection pins 144a via the following transmission path.

[0123] (Transmission path) Second rack bar 461a → Synchronous gear 462 → Second rack bar 461b

[0124] When the power of the boom side clutch gear 7 is transmitted to the pair of boom connecting pins 144a via the transmission path described above, the pair of boom connecting pins 144a move in a direction away from the pair of first boom pin receiving portions 142b.

[0125] 5B , when the electric motor 41 is driven in the second rotation direction, the motor-side clutch gear 6 rotates in the direction opposite to the arrow A3 in FIG. 5B (also referred to as the second rotation direction). In this embodiment, when the motor-side clutch gear 6 rotates in the second rotation direction in the state shown in FIG. 5B , the power of the motor-side clutch gear 6 is not transmitted to the boom-side clutch gear 7. In other words, the motor-side clutch gear 6 and the boom-side clutch gear 7 are configured to transmit power only when the motor-side clutch gear 6 rotates in a predetermined direction (the first rotation direction in this embodiment). This configuration can prevent the boom connection mechanism 46 from being unintentionally operated due to malfunction of the electric motor 41.

[0126] The position information detection device 44 detects that the pair of boom connecting pins 144a have been released from the pair of first boom pin receivers 142b of the intermediate boom 142 and have moved to a predetermined position (for example, the position shown in FIG. 4C ). Then, based on this detection result, the control unit stops the operation of the electric motor 41.

[0127] 4C, the states of the members of the pin moving mechanism 4 are as follows: Boom connection mechanism 46: contracted state Cylinder connection mechanism 45: extended state Boom connection pin 144a: extracted state Cylinder connection pins 454A, 454B: engaged state Electric motor 41: OFF Brake mechanism 42: ON Switching mechanism 5: first connected state

[0128] Next, the transition of the boom connecting mechanism 46 from the contracted state to the extended state is automatically performed based on the biasing force of the second biasing mechanism 463 when the brake mechanism 42 is in the OFF state while the electric motor 41 is not energized.

[0129] Specifically, when the brake mechanism 42 is in the OFF state while the boom connection mechanism 46 is in the contracted state, the boom side clutch gear 7 rotates in the direction indicated by arrow A4 in FIG. 5B based on the biasing force of the second biasing mechanism 463. The motor side clutch gear 6 also rotates together with the boom side clutch gear 7. The rotation direction at this time is the second rotation direction.

[0130] When the boom side clutch gear 7 rotates a predetermined amount, the boom side clutch gear 7 and the motor side clutch gear 6 stop rotating. As a result, the boom connection mechanism 46 transitions from the contracted state to the extended state.

[0131] Furthermore, when the boom connecting mechanism 46 transitions from the contracted state to the extended state and the boom side clutch gear 7 stops rotating in the second rotation direction, the motor side clutch gear 6 may rotate in the second rotation direction due to inertial force.

[0132] Then, when the motor side clutch gear 6 rotates in the second rotation direction while the boom side clutch gear 7 is stopped, the motor side clutch gear 6 may move in the direction of arrow A2 in Figure 5B (in other words, the second direction).

[0133] Specifically, when the motor side clutch gear 6 rotates in the second rotation direction, the first inclined surface 6111 of the motor side clutch gear 6 is guided by the boom side inclined surface 7121 of the boom side clutch gear 7 (in other words, pushed in the second direction), causing the motor side clutch gear 6 to move in the second direction.

[0134] At this time, the amount of movement of the motor-side clutch gear 6 in the second direction is at most the height of the motor-side first convex portion 611 and the boom-side convex portion 712. In the case of this embodiment, in the first coupled state of the switching mechanism 5 shown in FIG. 5B , the distance between the motor-side second tooth portion 62 (specifically, the motor-side second convex portion 622) of the motor-side clutch gear 6 and the cylinder-side tooth portion 811 (specifically, the cylinder-side convex portion 812) of the cylinder-side clutch gear 8 is greater than the height of the motor-side first convex portion 611 and the boom-side convex portion 712.

[0135] Therefore, even when the motor-side clutch gear 6 moves in the second direction, the motor-side clutch gear 6 does not engage with the cylinder-side clutch gear 8. Therefore, rotation is not transmitted from the cylinder-side clutch gear 8 to the cylinder coupling mechanism 45. As a result, unintentional operation of the cylinder coupling mechanism 45 can be reliably prevented.

[0136] Next, in the state shown in Figure 5B, the control unit (not shown) drives the clutch actuator (not shown) to move the motor-side clutch gear 6 in the second direction. At this time, the electric motor 41 is in the OFF state. Therefore, the motor-side clutch gear 6 does not rotate. The switching mechanism 5 then enters the state shown in Figure 5A. The state shown in Figure 5A is the neutral state of the switching mechanism 5.

[0137] An example of the operation of the switching mechanism 5 and the cylinder coupling mechanism 45 will be described with reference to FIGS. 3A to 3C, 6A, and 6B.

[0138] The cylinder coupling mechanism 45 transitions from an expanded state (see FIG. 3A) to a contracted state (see FIG. 3C) based on the power of the electric motor 41. This operation is referred to as the contraction operation of the cylinder coupling mechanism 45. This operation is also referred to as the withdrawal operation of the cylinder coupling mechanism 45. In the withdrawal operation of the cylinder coupling mechanism 45, the cylinder coupling mechanism 45 withdraws the cylinder coupling pins 454A, 454B from the cylinder pin receiving portions 1411, 1412.

[0139] The cylinder coupling mechanism 45 transitions from a contracted state to an expanded state based on the biasing force of the first biasing mechanism 455. This operation is referred to as the expanding operation of the cylinder coupling mechanism 45. This operation is also referred to as the return operation of the cylinder coupling mechanism 45. During the return operation of the cylinder coupling mechanism 45, the cylinder coupling mechanism 45 inserts the cylinder coupling pins 454A, 454B into the cylinder pin receiving portions 1411, 1412.

[0140] Before the cylinder coupling mechanism 45 performs the uncoupling operation, the switching mechanism 5 is in the state shown in Fig. 6A. The state shown in Fig. 6A is referred to as the neutral state, non-coupling state, or initial state of the switching mechanism 5. The state of the switching mechanism 5 shown in Fig. 6A is the same as the state of the switching mechanism 5 shown in Fig. 5A.

[0141] When the switching mechanism 5 is in the state shown in Figure 6A, the states of the members of the pin moving mechanism 4 are as follows: Boom connection mechanism 46: extended state Cylinder connection mechanism 45: extended state Boom connection pin 144a: engaged state Cylinder connection pins 454A, 454B: engaged state Electric motor 41: OFF Brake mechanism 42: OFF Switching mechanism 5: neutral state

[0142] When the switching mechanism 5 is in the neutral state, the motor-side clutch gear 6 is located in the neutral position. When the switching mechanism 5 is in the neutral state, the motor-side clutch gear 6 is not engaged with the cylinder-side clutch gear 8 and the boom-side clutch gear 7.

[0143] When the cylinder coupling mechanism 45 performs the disengagement operation, the motor-side clutch gear 6 moves from the neutral state toward the cylinder-side clutch gear 8. The moving direction of the motor-side clutch gear 6 at this time is also referred to as the second direction (the direction of arrow A2 in FIG. 6A ). The second direction is the other side in the axial direction of the motor-side clutch gear 6.

[0144] Specifically, the control unit (not shown) drives the clutch actuator (not shown) to move the motor-side clutch gear 6 in the second direction. At this time, the electric motor 41 is in the OFF state. Therefore, the motor-side clutch gear 6 does not rotate.

[0145] The switching mechanism 5 then enters the state shown in Fig. 6B. The state shown in Fig. 6B is referred to as the second coupled state of the switching mechanism 5. In the second coupled state of the switching mechanism 5, the motor-side clutch gear 6 engages with the cylinder-side clutch gear 8. In addition, the position of the motor-side clutch gear 6 in the state of the switching mechanism 5 shown in Fig. 6B is referred to as the second position.

[0146] Specifically, the motor-side second teeth 62 of the motor-side clutch gear 6 engage with the cylinder-side teeth 811 of the cylinder-side clutch gear 8. When the switching mechanism 5 enters the second connected state, the clutch actuator (not shown) stops. At this time, it is preferable that the motor-side clutch gear 6 is biased toward the cylinder-side clutch gear 8.

[0147] The second coupled state of the switching mechanism 5 is a state in which the rotation of the motor-side clutch gear 6 can be transmitted to the cylinder-side clutch gear 8. In the second coupled state of the switching mechanism 5, the motor-side second convex portion 622 of the motor-side second tooth portion 62 of the motor-side clutch gear 6 and the cylinder-side convex portion 812 of the cylinder-side tooth portion 811 of the cylinder-side clutch gear 8 are engaged in the circumferential direction.

[0148] Furthermore, in the second connected state of the switching mechanism 5, the second inclined surface 6221 of the motor side clutch gear 6 and the cylinder side inclined surface 8121 of the cylinder side clutch gear 8 engage (specifically, abut) while facing each other in the axial direction.

[0149] When the switching mechanism 5 is in the state shown in Figure 6B, the states of the members of the pin moving mechanism 4 are as follows: Boom connection mechanism 46: extended state Cylinder connection mechanism 45: extended state Boom connection pin 144a: engaged state Cylinder connection pins 454A, 454B: engaged state Electric motor 41: OFF Brake mechanism 42: OFF Switching mechanism 5: second connected state

[0150] Next, in the state shown in Fig. 6B, the control unit (not shown) turns on the electric motor 41. Then, the control unit drives the electric motor 41 in a first rotation direction. The power (rotation) of the electric motor 41 is transmitted to the motor-side clutch gear 6 via the transmission mechanism 43. Then, the motor-side clutch gear 6 rotates in the direction indicated by the arrow A3 in Fig. 6B (in other words, the first rotation direction).

[0151] In this embodiment, the rotation direction of the electric motor 41 when the power of the electric motor 41 is transmitted to the boom connection mechanism 46 (in other words, the second connection mechanism) is the same as the rotation direction of the electric motor 41 when the power of the electric motor 41 is transmitted to the cylinder connection mechanism 45 (in other words, the first connection mechanism).

[0152] In other words, the rotation direction of the motor-side clutch gear 6 during the unloading operation of the boom coupling mechanism 46 (i.e., the first rotation direction) is the same as the rotation direction of the motor-side clutch gear 6 during the unloading operation of the cylinder coupling mechanism 45 (i.e., the first rotation direction). This configuration contributes to reducing brush wear on the electric motor 41 when the electric motor 41 is a brushed DC motor. Furthermore, this configuration does not require a switching circuit for switching the rotation direction of the electric motor 41. As a result, the manufacturing costs of the mobile crane 1 can be reduced.

[0153] The power (rotation) of the electric motor 41 is transmitted from the motor side clutch gear 6 to the cylinder side clutch gear 8 by the motor side second convex portion 622 of the motor side second tooth portion 62 of the motor side clutch gear 6 pushing the cylinder side convex portion 812 of the cylinder side tooth portion 811 of the cylinder side clutch gear 8 in the circumferential direction (i.e., the first rotation direction).

[0154] As described above, when the electric motor 41 rotates, the cylinder-side clutch gear 8 engaged with the motor-side clutch gear 6 also rotates. The rotation of the cylinder-side clutch gear 8 is then transmitted to the cylinder coupling mechanism 45 (specifically, the first rack bar 451) via the cylinder-side pinion gear 83.

[0155] As a result, the cylinder coupling mechanism 45 transitions from the expanded state (see FIG. 3A) to the contracted state (see FIG. 3C). Specifically, the power transmitted from the cylinder-side clutch gear 8 to the first rack bar 451 is transmitted to the pair of cylinder coupling pins 454A, 454B via the following first and second transmission paths.

[0156] The first transmission path is a path through which the power of the cylinder-side clutch gear 8 is transmitted to the cylinder connecting pin 454A in the following order: (First Transmission Path) Cylinder-side clutch gear 8 → Cylinder-side pinion gear 83 → First rack bar 451 → First gear mechanism 452 → Cylinder connecting pin 454A

[0157] The second transmission path is a path through which the power of the cylinder-side clutch gear 8 is transmitted to the cylinder connecting pin 454B in the following order: (Second Transmission Path) Cylinder-side clutch gear 8 → Cylinder-side pinion gear 83 → First rack bar 451 → Second gear mechanism 453 → Cylinder connecting pin 454B

[0158] When the power of the cylinder side clutch gear 8 is transmitted to the cylinder connecting pin 454A via the first transmission path, the cylinder connecting pin 454A moves in a direction away from the cylinder pin receiving portion 1411 (to the left in FIG. 3A).

[0159] On the other hand, when the power of the cylinder side clutch gear 8 is transmitted to the cylinder connecting pin 454B via the second transmission path, the cylinder connecting pin 454A moves in the direction of coming out of the cylinder pin receiving portion 1412 (to the right in FIG. 3A).

[0160] 6B , when the electric motor 41 is driven in the second rotation direction, the motor-side clutch gear 6 rotates in the direction opposite to the arrow A3 in FIG. 6B (also referred to as the second rotation direction). In this embodiment, when the motor-side clutch gear 6 rotates in the second rotation direction in the state shown in FIG. 6B , the power of the motor-side clutch gear 6 is not transmitted to the cylinder-side clutch gear 8. In other words, the motor-side clutch gear 6 and the cylinder-side clutch gear 8 are configured to transmit power only when the motor-side clutch gear 6 rotates in a predetermined direction (the first rotation direction in this embodiment). This configuration can prevent the cylinder coupling mechanism 45 from being unintentionally operated due to a malfunction of the electric motor 41.

[0161] The position information detection device 44 detects that the pair of cylinder connecting pins 454A, 454B have been released from the pair of cylinder pin receivers 1411 of the tip boom 141 and have moved to a predetermined position (for example, the position shown in FIG. 3C ). Then, based on the detection result, the control unit (not shown) stops the operation of the electric motor 41.

[0162] When the cylinder connection mechanism 45 is in the contracted state, the states of the members of the pin moving mechanism 4 are as follows: Boom connection mechanism 46: extended state Cylinder connection mechanism 45: contracted state Boom connection pin 144a: engaged state Cylinder connection pins 454A, 454B: disengaged state Electric motor 41: OFF Brake mechanism 42: ON Switching mechanism 5: second connected state

[0163] Next, the transition of the cylinder connecting mechanism 45 from the contracted state to the expanded state is automatically performed based on the biasing force of the first biasing mechanism 455 when the brake mechanism 42 is in the OFF state while the electric motor 41 is not energized.

[0164] Specifically, when the brake mechanism 42 is in the OFF state while the cylinder coupling mechanism 45 is in the contracted state, the cylinder-side clutch gear 8 rotates in the direction indicated by arrow A4 in FIG. 6B based on the biasing force of the first biasing mechanism 455. The motor-side clutch gear 6 also rotates together with the cylinder-side clutch gear 8. The rotation direction at this time is the second rotation direction.

[0165] When the cylinder side clutch gear 8 rotates a predetermined amount, the rotation of the cylinder side clutch gear 8 and the motor side clutch gear 6 stops. As a result, the cylinder coupling mechanism 45 transitions from the contracted state to the expanded state.

[0166] When the cylinder coupling mechanism 45 transitions from the contracted state to the expanded state and the rotation of the cylinder-side clutch gear 8 in the second rotation direction stops, the motor-side clutch gear 6 may rotate independently in the second rotation direction due to inertia. If the motor-side clutch gear 6 rotates independently in the second rotation direction while the cylinder-side clutch gear 8 is stopped, the motor-side clutch gear 6 may move in the direction of arrow A1 in Figure 6B (i.e., the first direction).

[0167] Specifically, when the motor side clutch gear 6 rotates in the second rotation direction, the second inclined surface 6221 of the motor side clutch gear 6 is guided by the cylinder side inclined surface 8121 of the cylinder side clutch gear 8 (in other words, pushed in the first direction), causing the motor side clutch gear 6 to move in the first direction.

[0168] At this time, the maximum amount of movement of the motor-side clutch gear 6 in the first direction is the height of the motor-side second convex portion 622 and the cylinder-side convex portion 812. In the case of the present embodiment, in the second connected state of the switching mechanism 5 shown in FIG. 6B , the distance between the motor-side first tooth portion 61 (specifically, the motor-side first convex portion 611) of the motor-side clutch gear 6 and the boom-side tooth portion 711 (specifically, the boom-side convex portion 712) of the boom-side clutch gear 7 is greater than the height of the motor-side second convex portion 622 and the cylinder-side convex portion 812.

[0169] Therefore, even when the motor-side clutch gear 6 moves in the first direction, the motor-side clutch gear 6 does not engage with the boom-side clutch gear 7. Therefore, rotation is not transmitted from the cylinder-side clutch gear 8 to the boom-side clutch gear 7. As a result, unintentional operation of the boom connection mechanism 46 can be reliably prevented.

[0170] Next, in the state shown in FIG. 6B, the control unit (not shown) drives the clutch actuator (not shown) to move the motor-side clutch gear 6 in the first direction. At this time, the electric motor 41 is in the OFF state. Therefore, the motor-side clutch gear 6 does not rotate. Then, the switching mechanism 5 enters the neutral state shown in FIG. 6A.

[0171] In the case of the mobile crane 1 of this embodiment having the above-described configuration, because the cylinder coupling mechanism 45 and the boom coupling mechanism 46 are electrically operated, there is no need to provide a hydraulic circuit as in the conventional structure in the interior space of the telescopic boom 14. Therefore, the space that was previously used for the hydraulic circuit can be effectively utilized, improving the degree of freedom in designing the interior space of the telescopic boom 14.

[0172] Furthermore, in the case of the mobile crane 1 of this embodiment, the power of one electric motor 41 is selectively allocated to either the cylinder connection mechanism 45 or the boom connection mechanism 46 by the switching mechanism 5. This configuration contributes to the miniaturization of the pin moving mechanism 4. Other than that, the functions and effects of the mobile crane 1 of this embodiment are as described above.

[0173] [Embodiment 2] Next, a mobile crane 1B according to a second embodiment of the present invention will be described with reference to Figures 7A to 7C. In addition, for the configurations of the cylinder coupling mechanism 45 and the boom coupling mechanism 46, reference will be made to Figures 3A to 3C and 4A to 4C.

[0174] Figures 7A to 7C are diagrams showing the configuration of the switching mechanism 5B of the pin moving mechanism 4B incorporated in the mobile crane 1B. The state of the switching mechanism 5B shown in Figure 7A corresponds to the state of the switching mechanism 5 shown in Figures 5A and 6A described above. The state of the switching mechanism 5B shown in Figure 7B corresponds to the state of the switching mechanism 5 shown in Figure 5B described above. The state of the switching mechanism 5B shown in Figure 7C corresponds to the state of the switching mechanism 5 shown in Figure 6B described above.

[0175] The switching mechanism 5B has a motor-side clutch gear 6B, a cylinder-side clutch gear 8B, a boom-side clutch gear 7B, and a clutch actuator 9. Below, the configuration of the mobile crane 1B according to this embodiment that differs from the configuration of the mobile crane 1 according to the first embodiment described above will be described.

[0176] The motor-side clutch gear 6B has a first gear element 6a, a second gear element 6b, and a connecting shaft portion 6c.

[0177] The first gear element 6a is provided on the boom-side clutch gear 7B side. The first gear element 6a has a motor-side first tooth portion 61B at the end on the boom-side clutch gear 7B side. The configuration of the motor-side first tooth portion 61B is similar to the configuration of the motor-side first tooth portion 61 in the first embodiment described above. Therefore, the description of the configuration of the motor-side first tooth portion 61 in the first embodiment described above may be used as appropriate for the description of the configuration of the motor-side first tooth portion 61B.

[0178] The second gear element 6b is provided on the cylinder-side clutch gear 8B side. The second gear element 6b has a motor-side second tooth portion 62B at the end on the cylinder-side clutch gear 8B side. The configuration of the motor-side second tooth portion 62B is similar to the configuration of the motor-side second tooth portion 62 in the first embodiment described above. Therefore, the description of the configuration of the motor-side second tooth portion 62 in the first embodiment may be used as appropriate for the description of the configuration of the motor-side second tooth portion 62.

[0179] The connecting shaft 6c is a cylindrical shaft member that connects the first gear element 6a and the second gear element 6b in the axial direction. The connecting shaft 6c is connected to the electric motor 41. When the electric motor 41 rotates, the connecting shaft 6c rotates.

[0180] The boom side clutch gear 7B is connected to the boom connecting mechanism 46 (see FIGS. 4A to 4C). The boom side clutch gear 7B transmits the power of the electric motor 41, which is transmitted from the motor side clutch gear 6B, to the boom connecting mechanism 46.

[0181] The boom side clutch gear 7B has a gear body 71B. The configuration of the gear body 71B is substantially the same as the configuration of the gear body 71 of the boom side clutch gear 7 in the first embodiment described above. Therefore, the description of the configuration of the gear body 71B may be appropriately cited for the description of the configuration of the gear body 71 in the first embodiment described above. Furthermore, a boom side pinion gear 73B is fixed to the gear body 71B. The configuration of the boom side pinion gear 73B is substantially the same as the boom side pinion gear 73 in the first embodiment described above. Therefore, the description of the configuration of the boom side pinion gear 73B may be appropriately cited for the description of the configuration of the boom side pinion gear 73 in the first embodiment described above.

[0182] The cylinder side clutch gear 8B is connected to a cylinder coupling mechanism 45 (see FIGS. 3A to 3C). The cylinder side clutch gear 8B transmits the power of the electric motor 41, which is transmitted from the motor side clutch gear 6B, to the cylinder coupling mechanism 45.

[0183] The cylinder side clutch gear 8B has a gear body 81B. The configuration of the gear body 81B is substantially the same as the configuration of the gear body 81 of the cylinder side clutch gear 8 in the first embodiment described above. Therefore, the description of the configuration of the gear body 81B may be appropriately cited for the description of the configuration of the gear body 81 in the first embodiment described above. In addition, a cylinder side pinion gear 83B is fixed to the gear body 81B. The configuration of the cylinder side pinion gear 83B is substantially the same as the cylinder side pinion gear 83 in the first embodiment described above. Therefore, the description of the configuration of the cylinder side pinion gear 83B may be appropriately cited for the description of the configuration of the cylinder side pinion gear 83 in the first embodiment described above.

[0184] The clutch actuator 9 is an example of a drive unit and includes a first drive unit 91 a, a first spring 92 a, a first pressing unit 93 a, a second drive unit 91 b, a second spring 92 b, and a second pressing unit 93 b. The clutch actuator 9 is supported by, for example, a fixed unit 99. The fixed unit 99 may be, for example, a trunnion (not shown) that supports the pin moving mechanism 4 or a member supported by the trunnion.

[0185] The first driving unit 91a is an actuator that generates power in the axial direction, and is, for example, a solenoid actuator that is expandable and contractible in the axial direction.

[0186] The first spring 92a is an example of an elastic member and transmits the power of the first drive unit 91a to the motor-side clutch gear 6B. The first spring 92a biases the motor-side clutch gear 6B toward the boom connection mechanism 46 when the power of the electric motor 41 can be transmitted to the boom connection mechanism 46 (see FIG. 4A).

[0187] The first spring 92a is disposed between the first drive portion 91a and the first pressing portion 93a. One end (also referred to as the first end) of the first spring 92a is connected to the tip of the first drive portion 91a. The other end (also referred to as the second end) of the first spring 92a is connected to the first pressing portion 93a.

[0188] When the first drive portion 91a extends in a first direction (the direction indicated by the arrow A1 in FIG. 7A ), the first drive portion 91a presses the first spring 92a in the first direction. Then, the first spring 92a presses the first pressing portion 93a in the first direction.

[0189] The first pressing portion 93a is a member for pressing the first gear element 6a of the motor-side clutch gear 6B in a first direction. The first pressing portion 93a is supported by the fixed portion 99 in a state in which it can move in the axial direction. The first pressing portion 93a is plate-shaped.

[0190] The first pressing portion 93a has a through-hole 930a that passes through the first pressing portion 93a in the axial direction. The connecting shaft 6c of the motor-side clutch gear 6B is inserted into the through-hole 930a. The first pressing portion 93a faces the first gear element 6a of the motor-side clutch gear 6B in the axial direction.

[0191] The second drive unit 91b is an actuator that generates power in the axial direction. The second drive unit 91b is, for example, a solenoid actuator that is expandable and contractible in the axial direction. The second spring 92b is provided between the second drive unit 91b and the second pressing unit 93b.

[0192] The second spring 92b is an example of an elastic member and transmits the power of the second drive unit 91b to the motor-side clutch gear 6B. The second spring 92b biases the motor-side clutch gear 6B toward the cylinder coupling mechanism 45 (see FIG. 3A) when the power of the electric motor 41 can be transmitted to the cylinder coupling mechanism 45.

[0193] One end (also referred to as a first end) of the second spring 92b is connected to the tip of the second drive portion 91b, and the other end (also referred to as a second end) of the second spring 92b is connected to the second pressing portion 93b.

[0194] When the second drive portion 91b extends in the second direction (the direction indicated by the arrow A2 in FIG. 7A ), the second drive portion 91b presses the second spring 92b in the second direction. The second spring 92b is an example of an elastic member and presses the second pressing portion 93b in the second direction.

[0195] The second pressing portion 93b is a member for pressing the second gear element 6b of the motor-side clutch gear 6B in the second direction. The second pressing portion 93b is supported by the fixed portion 99 in a state in which it can move in the axial direction. The second pressing portion 93b is plate-shaped.

[0196] The second pressing portion 93b has a through-hole 930b that passes through the second pressing portion 93b in the axial direction. The connecting shaft 6c of the motor-side clutch gear 6B is inserted into the through-hole 930b. The second pressing portion 93b faces the second gear element 6b of the motor-side clutch gear 6B in the axial direction.

[0197] Next, the operation of the switching mechanism 5B will be described. Note that, except for the configuration in which the clutch actuator 9 moves the motor-side clutch gear 6B, the operation is the same as that of the switching mechanism 5 in the first embodiment described above.

[0198] First, with reference to FIGS. 7A and 7B, the operation of the switching mechanism 5B when performing the retracting operation of the boom connecting mechanism 46 will be briefly described.

[0199] When the boom connecting mechanism 46 is to be retracted, the control unit (not shown) drives the clutch actuator 9 to move the motor-side clutch gear 6B in the first direction (the direction indicated by the arrow A1 in FIG. 7A ). At this time, the electric motor 41 is in the OFF state. Therefore, the motor-side clutch gear 6B does not rotate.

[0200] Specifically, the control unit (not shown) drives the first drive unit 91a of the clutch actuator 9. As a result, the first drive unit 91a extends in a first direction as shown in FIG. 7B . When the first drive unit 91a extends, the first drive unit 91a pushes the first spring 92a in the first direction. When the first spring 92a is pushed in the first direction by the first drive unit 91a, the first spring 92a pushes the first pressing unit 93a in the first direction.

[0201] 7A in the first direction. When the first pressing portion 93a moves a predetermined amount in the first direction, the first pressing portion 93a comes into contact with the first gear element 6a of the motor-side clutch gear 6B. When the first driving portion 91a further extends in the first direction from this state, the first pressing portion 93a presses the first gear element 6a in the first direction.

[0202] As a result, as shown in Figure 7B, the first gear element 6a engages with the boom side clutch gear 7B. With the first gear element 6a engaged with the boom side clutch gear 7B, the rotation of the motor side clutch gear 6B can be transmitted to the boom side clutch gear 7B. The state in which the first gear element 6a engages with the boom side clutch gear 7B is the first engaged state of the switching mechanism 5B.

[0203] In this state, a control unit (not shown) turns on the electric motor 41 (see FIG. 4A). Then, the control unit drives the electric motor 41 in a first rotation direction. The power (rotation) of the electric motor 41 is transmitted to the motor-side clutch gear 6 via a transmission mechanism 43 (see FIG. 4A). As a result, the motor-side clutch gear 6B rotates in the direction of arrow A3 in FIG. 7B. The rotation direction of the motor-side clutch gear 6B at this time is referred to as the first rotation direction of the motor-side clutch gear 6B.

[0204] The power (rotation) of the electric motor 41 is transmitted to the boom-side clutch gear 7B via the motor-side clutch gear 6 (specifically, the first gear element 6a). Therefore, the boom-side clutch gear 7B rotates in the first rotation direction.

[0205] In this way, the power of the electric motor 41 is transmitted to the boom side clutch gear 7B. The power of the electric motor 41 is transmitted to the boom connecting mechanism 46 (see FIG. 4A) via the boom side clutch gear 7B.

[0206] Then, the boom connection mechanism 46 transitions from the extended state shown in Fig. 4A to the retracted state shown in Fig. 4C. As a result, the boom connection mechanism 46 is pulled out, and the pair of boom connection pins 144a are released from the pair of first boom pin receivers 142b of the intermediate boom 142.

[0207] Furthermore, the closing operation of the boom connection mechanism 46 is performed automatically based on the biasing force of the second biasing mechanism 463. Specifically, the boom side clutch gear 7B rotates in the direction of arrow A4 in Figure 7B based on the biasing force of the second biasing mechanism 463. The rotation direction at this time is the second rotation direction. Then, when the boom side clutch gear 7B rotates a predetermined amount, the rotation of the boom side clutch gear 7B and the motor side clutch gear 6B stops.

[0208] As described in the description of the first embodiment above, if the boom side clutch gear 7B stops during the closing operation of the boom connecting mechanism 46, there is a possibility that the motor side clutch gear 6B will rotate in the second rotation direction due to inertial force.

[0209] When the motor-side clutch gear 6B rotates in the second rotation direction while the boom-side clutch gear 7B is stopped, the motor-side clutch gear 6B may move in the direction of arrow A2 in Fig. 7B (i.e., the second direction), for the reasons described in the first embodiment.

[0210] However, in the present embodiment, when the switching mechanism 5B is in the first engaged state, the first pressing portion 93a constantly urges the motor-side clutch gear 6B in the direction of arrow A1 in Figure 7B (i.e., the first direction) based on the urging force of the first spring 92a.

[0211] Therefore, even if the motor side clutch gear 6B moves in the second direction, the motor side clutch gear 6B returns to its original position (i.e., the position of the motor side clutch gear 6B in Figure 7B) based on the biasing force of the first spring 92a.

[0212] Even when the motor-side clutch gear 6B moves in the second direction in this way, the motor-side clutch gear 6B does not engage with the cylinder-side clutch gear 8B, and therefore rotation is not transmitted from the cylinder-side clutch gear 8B to the cylinder coupling mechanism 45. This reliably prevents the cylinder coupling mechanism 45 from operating unintentionally.

[0213] 7B, if the electric motor 41 malfunctions and is driven in the second rotation direction, the power (i.e., rotation) of the electric motor 41 is transmitted to the motor-side clutch gear 6 via the transmission mechanism 43 (see FIGS. 3A to 4C). Then, the motor-side clutch gear 6B rotates in the direction opposite to the direction of arrow A3 in FIG. 7B (i.e., the second rotation direction).

[0214] At this time, the rotation of the motor-side clutch gear 6B is not transmitted to the boom-side clutch gear 7B. Therefore, there is no risk of malfunction of the boom connection mechanism 46. As described above, in the present embodiment, the power (i.e., rotation) of the electric motor 41 is transmitted to the boom connection mechanism 46 only when the clutch actuator 9 (specifically, the first drive unit 91a) and the electric motor 41 operate in a correct corresponding relationship.

[0215] In other words, if the clutch actuator 9 (specifically, the first drive unit 91a) and the electric motor 41 operate in an incorrect correspondence, the power (i.e., rotation) of the electric motor 41 will not be transmitted to the boom connection mechanism 46.

[0216] 7A and 7C, the removal operation of the cylinder coupling mechanism 45 will be described. When the cylinder coupling mechanism 45 performs the removal operation of the cylinder coupling mechanism 45, the motor-side clutch gear 6 moves from the neutral state shown in Fig. 7A toward the cylinder-side clutch gear 8B. The moving direction of the motor-side clutch gear 6B at this time is also referred to as the second direction (the direction indicated by arrow A2 in Fig. 7A).

[0217] Specifically, the control unit (not shown) drives the clutch actuator 9 to move the motor-side clutch gear 6B in the second direction. At this time, the electric motor 41 is in the OFF state. Therefore, the motor-side clutch gear 6B does not rotate.

[0218] More specifically, the control unit (not shown) drives the second drive unit 91b of the clutch actuator 9. As a result, the second drive unit 91b extends in the second direction as shown in FIG. 7C . When the second drive unit 91b extends, the second drive unit 91b pushes the second spring 92b in the second direction. When the second spring 92b is pushed in the second direction by the second drive unit 91b, the second spring 92b pushes the second pressing unit 93b in the second direction.

[0219] 7A in the second direction. When the second pressing portion 93b moves a predetermined amount in the second direction, the second pressing portion 93b comes into contact with the second gear element 6b of the motor-side clutch gear 6B. When the second drive portion 91b further extends in the second direction from this state, the second pressing portion 93b presses the second gear element 6b in the second direction.

[0220] As a result, as shown in Figure 7C, the second gear element 6b engages with the cylinder-side clutch gear 8B. With the second gear element 6b engaged with the cylinder-side clutch gear 8B, the rotation of the motor-side clutch gear 6B can be transmitted to the cylinder-side clutch gear 8B. The state in which the second gear element 6b engages with the cylinder-side clutch gear 8B is the second engaged state of the switching mechanism 5B.

[0221] In this state, the control unit (not shown) turns on the electric motor 41. Then, the control unit drives the electric motor 41 in the second rotation direction. The power (rotation) of the electric motor 41 is transmitted to the motor-side clutch gear 6 via the transmission mechanism 43.

[0222] As a result, the motor-side clutch gear 6B rotates in the direction of arrow A4 in Figure 7C. The rotation direction of the motor-side clutch gear 6B at this time is the second rotation direction, which is opposite to the first rotation direction.

[0223] In this embodiment, the rotation direction of the electric motor 41 when the power of the electric motor 41 is transmitted to the boom connection mechanism 46 (in other words, the second connection mechanism) is opposite to the rotation direction of the electric motor 41 when the power of the electric motor 41 is transmitted to the cylinder connection mechanism 45 (in other words, the first connection mechanism).

[0224] The power (rotation) of the electric motor 41 is transmitted to the cylinder-side clutch gear 8B via the motor-side clutch gear 6 (specifically, the second gear element 6b), causing the cylinder-side clutch gear 8B to rotate in the second rotation direction.

[0225] Note that the electric motor 41 may rotate in the first rotation direction during the retraction operation of the cylinder coupling mechanism 45. In other words, the rotation direction of the electric motor 41 during the retraction operation of the cylinder coupling mechanism 45 may be the same as the rotation direction of the electric motor 41 during the retraction operation of the boom coupling mechanism 46.

[0226] In this way, the power of the electric motor 41 is transmitted to the cylinder side clutch gear 8B. The power of the electric motor 41 is transmitted to the cylinder connecting mechanism 45 via the cylinder side clutch gear 8B.

[0227] Then, the cylinder coupling mechanism 45 transitions from the expanded state shown in Fig. 3A to the contracted state shown in Fig. 3C. As a result, the cylinder coupling mechanism 45 is pulled out, and the pair of cylinder coupling pins 454A, 454B are released from the pair of cylinder pin receivers 1411, 1412 of the tip boom 141.

[0228] Furthermore, when the brake mechanism 42 is turned off while the cylinder coupling mechanism 45 is in the contracted state, the cylinder coupling mechanism 45 transitions from the contracted state to the expanded state. That is, the closing operation of the cylinder coupling mechanism 45 is performed. The closing operation of the cylinder coupling mechanism 45 is performed automatically based on the biasing force of the first biasing mechanism 455.

[0229] Specifically, the cylinder-side clutch gear 8B rotates in the direction indicated by arrow A3 in Figure 7C based on the biasing force of the first biasing mechanism 455. The rotation direction at this time is the first rotation direction. Then, when the cylinder-side clutch gear 8B rotates a predetermined amount, the rotation of the cylinder-side clutch gear 8B and the motor-side clutch gear 6B stops.

[0230] As described in the description of the first embodiment above, if the cylinder-side clutch gear 8B stops during the engagement operation of the cylinder coupling mechanism 45, the motor-side clutch gear 6B may rotate in the first rotation direction due to inertia. If the motor-side clutch gear 6B rotates in the first rotation direction while the cylinder-side clutch gear 8B is stopped, the motor-side clutch gear 6B may move in the direction of arrow A1 in Figure 7C (i.e., the first direction). The reason for this is as described in the first embodiment.

[0231] However, in this embodiment, when the switching mechanism 5B is in the second engaged state, the second pressing portion 93b constantly urges the motor-side clutch gear 6B in the direction of arrow A2 in Fig. 7C (i.e., the second direction) based on the urging force of the second spring 92b. Therefore, even if the motor-side clutch gear 6B moves in the direction of arrow A1 in Fig. 7C (i.e., the first direction), the motor-side clutch gear 6B returns to its original position (i.e., the position of the motor-side clutch gear 6B in Fig. 7C) based on the urging force of the second spring 92b.

[0232] Even when the motor-side clutch gear 6B moves in the first direction in this way, the motor-side clutch gear 6B does not engage with the boom-side clutch gear 7B. Therefore, rotation is not transmitted from the boom-side clutch gear 7B to the boom connection mechanism 46. This reliably prevents the boom connection mechanism 46 from operating unintentionally.

[0233] 7C, if the electric motor 41 malfunctions and is driven in the first rotation direction, the power (i.e., rotation) of the electric motor 41 is transmitted to the motor-side clutch gear 6 via the transmission mechanism 43 (see FIGS. 3A to 4C). Then, the motor-side clutch gear 6B rotates in the direction opposite to the direction of arrow A4 in FIG. 7C (i.e., the first rotation direction).

[0234] At this time, the rotation of the motor-side clutch gear 6B is not transmitted to the cylinder-side clutch gear 8B, and therefore the cylinder coupling mechanism 45 does not malfunction. Thus, in this embodiment, the power (i.e., rotation) of the electric motor 41 is transmitted to the cylinder coupling mechanism 45 only when the clutch actuator 9 (specifically, the second drive unit 91b) and the electric motor 41 operate in a correct corresponding relationship.

[0235] In other words, if the clutch actuator 9 (specifically, the second drive unit 91b) and the electric motor 41 operate in an incorrect correspondence relationship, the power (i.e., rotation) of the electric motor 41 will not be transmitted to the cylinder coupling mechanism 45. The rest of the configuration, actions, and effects of the mobile crane 1B are the same as those of the mobile crane 1 according to the first embodiment described above. Note that the configuration of the switching mechanism 5B (particularly the motor-side clutch gear 6B and the clutch actuator 9) in this embodiment is also applicable to the switching mechanism 5 in the first embodiment described above.

[0236] [Embodiment 3] Next, a mobile crane 1C according to a third embodiment of the present invention will be described with reference to Figures 8A and 8B. In addition, for the configurations of the cylinder coupling mechanism 45 and the boom coupling mechanism 46, reference will be made to Figures 3A to 3C and 4A to 4C.

[0237] 8A and 8B are diagrams showing the configuration of a switching mechanism 5C of a pin moving mechanism 4C incorporated in a mobile crane 1C.

[0238] In the mobile crane 1C of this embodiment, the configuration of the switching mechanism 5C is different from the configuration of the switching mechanism 5 of the mobile crane 1 according to the above-described embodiment 1. The configuration of the switching mechanism 5C will be described below.

[0239] The operation of the cylinder coupling mechanism 45 and the boom coupling mechanism 46 is similar to that of the cylinder coupling mechanism 45 and the boom coupling mechanism 46 of the mobile crane 1 according to the above-described embodiment 1. Therefore, with regard to the configuration and operation of the cylinder coupling mechanism 45 and the boom coupling mechanism 46, explanations that overlap with those of the above-described embodiment 1 will be omitted.

[0240] The switching mechanism 5C selectively engages with one of the cylinder connecting mechanism 45 and the boom connecting mechanism 46, and transmits the power of the electric motor 41 to the one connecting mechanism. The switching mechanism 5C has a motor-side clutch gear 6C, a boom-side clutch gear 7C, and a cylinder-side clutch gear 8C.

[0241] The configurations of the motor side clutch gear 6C, boom side clutch gear 7C, and cylinder side clutch gear 8C are substantially the same as the configurations of the motor side clutch gear 6, boom side clutch gear 7, and cylinder side clutch gear 8 in the first embodiment described above.

[0242] Therefore, among the configurations of the motor side clutch gear 6C, boom side clutch gear 7C, and cylinder side clutch gear 8C, the same configurations as the motor side clutch gear 6, boom side clutch gear 7, and cylinder side clutch gear 8 in the above-mentioned first embodiment are given the same symbols as the motor side clutch gear 6, boom side clutch gear 7, and cylinder side clutch gear 8 in the first embodiment.

[0243] For the configurations of the motor side clutch gear 6C, boom side clutch gear 7C, and cylinder side clutch gear 8C, the descriptions of the motor side clutch gear 6, boom side clutch gear 7, and cylinder side clutch gear 8 in embodiment 1 may be used as appropriate.

[0244] 8A and 8B are diagrams showing the state of the switching mechanism 5C when the boom connecting mechanism 46 performs the retracting operation and the retracting operation. Hereinafter, the operation of the switching mechanism 5C will be described with reference to FIGS. 8A and 8B.

[0245] 8A shows the initial state of the switching mechanism 5C. In the initial state of the switching mechanism 5C, the motor-side clutch gear 6C, the boom-side clutch gear 7C, and the cylinder-side clutch gear 8C are all in their initial positions. In the initial state of the switching mechanism 5C (in other words, the second position), the motor-side clutch gear 6C is engaged with the cylinder-side clutch gear 8C.

[0246] The state of the switching mechanism 5C shown in FIG. 8A is also the state of the switching mechanism 5C before the boom connection mechanism 46 performs the retracting operation of the boom connection mechanism 46.

[0247] When the boom connection mechanism 46 performs the operation of extracting the boom connection mechanism 46, the motor-side clutch gear 6C moves toward the boom-side clutch gear 7C. The moving direction of the motor-side clutch gear 6C at this time is also referred to as a first direction (the direction indicated by the arrow A1 in FIG. 8A ).

[0248] Specifically, the control unit (not shown) drives the electric motor 41 to rotate the motor-side clutch gear 6C in the direction indicated by the arrow A3 in Fig. 8A. At this time, the rotation direction of the electric motor 41 and the motor-side clutch gear 6C is the first rotation direction.

[0249] When the motor side clutch gear 6C rotates in the first rotation direction, the second inclined surface 6221 of the motor side second convex portion 622 on the motor side clutch gear 6C is guided by the cylinder side inclined surface 8121 of the cylinder side convex portion 812 on the cylinder side clutch gear 8C (in other words, pushed in the first direction), and the motor side clutch gear 6C moves in the direction of arrow A1 in Figure 8A (in other words, the first direction).

[0250] At this time, the amount of movement of the motor-side clutch gear 6C is equal to the height H1 (see FIG. 8A) of the cylinder-side protrusion 812. In this way, when the motor-side clutch gear 6C moves in the first direction by the height H1 of the cylinder-side protrusion 812, the motor-side clutch gear 6C engages with the boom-side clutch gear 7C (see FIG. 8B). In the switching mechanism 5C in the state shown in FIG. 8B, the position of the motor-side clutch gear 6C is the first position.

[0251] Thus, in the case of this embodiment, when the motor-side clutch gear 6C rotates in the first rotational direction in the second connected state in which the power of the electric motor 41 can be transmitted to the cylinder-side clutch gear 8C, it is guided by the cylinder-side clutch gear 8C (in other words, the second transmission member) and moves to a first position (the position of the motor-side clutch gear 6C in Figure 8B) corresponding to the first connected state in which the power of the electric motor 41 can be transmitted to the boom-side clutch gear 7C (in other words, the first transmission member).

[0252] As described above, the switching mechanism 5C of this embodiment does not have a clutch actuator for axially moving the motor-side clutch gear 6C. In other words, in the case of the switching mechanism 5C of this embodiment, the electric motor 41 functions as the clutch actuator (i.e., the drive unit).

[0253] In the state shown in Figure 8B, the switching mechanism 5C is in the first coupled state. In the first coupled state of the switching mechanism 5C, the motor-side clutch gear 6C is engaged with the boom-side clutch gear 7C. The state of the switching mechanism 5C shown in Figure 8A is referred to as the second coupled state.

[0254] In the state shown in FIG. 8B, the motor-side first tooth portion 61 of the motor-side clutch gear 6C engages with the boom-side tooth portion 711 of the boom-side clutch gear 7C.

[0255] The first coupled state of the switching mechanism 5C is a state in which rotation of the motor-side clutch gear 6C can be transmitted to the boom-side clutch gear 7C. In the first coupled state of the switching mechanism 5C, the motor-side first convex portion 611 of the motor-side first tooth portion 61 of the motor-side clutch gear 6C and the boom-side convex portion 712 of the boom-side tooth portion 711 of the boom-side clutch gear 7C are engaged in the circumferential direction.

[0256] Furthermore, in the first connected state of the switching mechanism 5C, the first inclined surface 6111 of the motor side clutch gear 6C and the boom side inclined surface 7121 of the boom side clutch gear 7C engage (specifically, abut) while facing each other in the axial direction.

[0257] Next, in the state shown in Fig. 8B, the control unit (not shown) further drives the electric motor 41 (see Fig. 4A) in the first rotational direction. As a result, the motor-side clutch gear 6C further rotates in the first rotational direction. The power (rotation) of the electric motor 41 is transmitted from the motor-side clutch gear 6C to the boom-side clutch gear 7C. In addition, the rotation of the boom-side clutch gear 7C is transmitted to the boom connecting mechanism 46 (see Fig. 4A).

[0258] As a result, the boom connection mechanism 46 transitions from the extended state (the state shown in FIG. 4A) to the retracted state (the state shown in FIG. 4C). In this state, the control unit (not shown) turns on the brake mechanism 42. Thereafter, the control unit (not shown) turns off the electric motor 41. The retracted state of the boom connection mechanism 46 is then maintained.

[0259] Next, in the state shown in Fig. 8B, the boom connection mechanism 46 performs the retracting operation of the boom connection mechanism 46. The retracting operation of the boom connection mechanism 46 is performed automatically based on the biasing force of the second biasing mechanism 463 (see Fig. 4A).

[0260] Specifically, in the state of the switching mechanism 5C shown in Fig. 8B, the boom side clutch gear 7C rotates in the direction indicated by arrow A4 in Fig. 8B based on the biasing force of the second biasing mechanism 463. The rotation direction at this time is the second rotation direction.

[0261] When the boom-side clutch gear 7C rotates a predetermined amount, the boom-side clutch gear 7C and the motor-side clutch gear 6C stop rotating in the second rotation direction. The boom connection mechanism 46 then transitions from the contracted state (the state shown in FIG. 4C ) to the extended state (the state shown in FIG. 4A ). In this state, the boom connection pin 144a is in the engaged state.

[0262] When the cylinder coupling mechanism 45 is removed from the state shown in Fig. 8B, the control unit (not shown) drives the electric motor 41 in the second rotation direction, causing the motor-side clutch gear 6C to rotate in the direction indicated by the arrow A4 in Fig. 8B.

[0263] When the motor side clutch gear 6C rotates in the second rotation direction, the first inclined surface 6111 of the motor side first convex portion 611 on the motor side clutch gear 6C is guided by the boom side inclined surface 7121 of the boom side convex portion 712 on the boom side clutch gear 7C (in other words, pushed in the second direction), and the motor side clutch gear 6C moves in the direction of arrow A2 in Figure 8A (in other words, the second direction).

[0264] Thus, in the case of this embodiment, when the motor-side clutch gear 6C rotates in the second rotation direction in the first connected state in which the power of the electric motor 41 can be transmitted to the boom-side clutch gear 7C, it is guided by the boom-side clutch gear 7C (in other words, the first transmission member) and moves to the second position (the position of the motor-side clutch gear 6C in FIG. 8A ) corresponding to the second connected state in which the power of the electric motor 41 can be transmitted to the cylinder-side clutch gear 8C (in other words, the second transmission member). Then, the motor-side clutch gear 6C engages with the cylinder-side clutch gear 8C.

[0265] The control unit (not shown) then further drives the electric motor 41 in the second rotation direction, causing the motor-side clutch gear 6C to further rotate in the direction indicated by arrow A4 in Fig. 8A. At this time, the rotation direction of the motor-side clutch gear 6C and the electric motor 41 is the second rotation direction.

[0266] When the motor-side clutch gear 6C rotates in the second rotational direction, the cylinder-side clutch gear 8C rotates in the second rotational direction. The rotation of the cylinder-side clutch gear 8C is then transmitted to the cylinder coupling mechanism 45. As a result, the cylinder coupling mechanism 45 transitions from the expanded state (see FIG. 3A) to the contracted state (see FIG. 3C). The engaging operation of the cylinder coupling mechanism 45 is performed automatically based on the biasing force of the first biasing mechanism 455.

[0267] In the case of the mobile crane 1C according to this embodiment having the above-described configuration, the electric motor 41 functions as a clutch actuator that moves the motor-side clutch gear 6C of the switching mechanism 5C. This configuration contributes to the miniaturization of the switching mechanism 5C.

[0268] [Fourth Embodiment] Next, a mobile crane 1D according to a fourth embodiment of the present invention will be described with reference to Figures 9A and 9B. Figures 9A and 9B are diagrams showing the configuration of a switching mechanism 5D of a pin moving mechanism 4D incorporated in the mobile crane 1D.

[0269] The mobile crane 1D of this embodiment has a switching mechanism 5D whose configuration differs from the switching mechanism 5C of the mobile crane 1C of the above-described embodiment 3. The differences between the switching mechanism 5D and the switching mechanism 5C will be described below.

[0270] The motor-side clutch gear 6D of the switching mechanism 5D has a motor-side first tooth portion 61D and a motor-side second tooth portion 62D.

[0271] The motor-side first tooth portion 61D has a motor-side first convex portion 611D. The motor-side first convex portion 611D has a motor-side first long convex portion 611a and a motor-side first short convex portion 611b. The axial length of the motor-side first long convex portion 611a is longer than the axial length of the motor-side first short convex portion 611b. In other words, the tip of the motor-side first long convex portion 611a is closer to the boom-side clutch gear 7D than the tip of the motor-side first short convex portion 611b.

[0272] The motor-side first long protrusions 611a are provided at two locations in the circumferential direction of the motor-side first teeth portion 61D, while the motor-side first short protrusions 611b are provided at four locations in the circumferential direction of the motor-side first teeth portion 61D.

[0273] The two motor-side first long convex portions 611a and the four motor-side first short convex portions 611b are arranged at equal intervals (60-degree intervals) in the circumferential direction of the motor-side first tooth portion 61D. The two motor-side first long convex portions 611a are arranged diagonally opposite each other. Two motor-side first short convex portions 611b are arranged at positions sandwiched between the two motor-side first long convex portions 611a in the circumferential direction. Note that the number of motor-side first long convex portions 611a may be one. In this case, the number of motor-side first short convex portions 611b may be, for example, five.

[0274] The motor-side second tooth portion 62D has a motor-side second convex portion 622D. The motor-side second convex portion 622D has a motor-side second long convex portion 622a and a motor-side second short convex portion 622b. The axial length of the motor-side second long convex portion 622a is longer than the axial length of the motor-side second short convex portion 622b. In other words, the tip of the motor-side second long convex portion 622a is closer to the cylinder-side clutch gear 8D than the tip of the motor-side second short convex portion 622b.

[0275] The motor-side second long protrusions 622a are provided at two locations in the circumferential direction of the motor-side second toothed portion 62D, while the motor-side second short protrusions 622b are provided at four locations in the circumferential direction of the motor-side second toothed portion 62D.

[0276] The two motor-side second long protrusions 622a and the four motor-side second short protrusions 622b are arranged at equal intervals (60-degree intervals) in the circumferential direction of the motor-side second tooth portion 62D. The two motor-side second long protrusions 622a are arranged diagonally opposite each other. Two motor-side second short protrusions 622b are arranged at positions sandwiched between the two motor-side second long protrusions 622a in the circumferential direction. Note that the number of motor-side second long protrusions 622a may be one. In this case, the number of motor-side second short protrusions 622b may be, for example, five.

[0277] The boom side clutch gear 7D has a boom side toothed portion 711D. The boom side toothed portion 711D has a plurality of boom side convex portions 712 that are provided side by side and spaced apart in the circumferential direction.

[0278] The boom-side convex portion 712 has a long convex portion 712a and a short convex portion 712b. The long convex portion 712a is an example of a first long convex portion. The short convex portion 712b is an example of a first short convex portion. The axial length of the long convex portion 712a is longer than the axial length of the short convex portion 712b. In other words, the tip of the long convex portion 712a is closer to the motor-side clutch gear 6D than the tip of the short convex portion 712b.

[0279] The long convex portions 712a are provided at two locations in the circumferential direction of the boom side toothed portion 711D. On the other hand, the short convex portions 712b are provided at four locations in the circumferential direction of the boom side toothed portion 711D. In other words, the boom side convex portion 712 has six convex portions.

[0280] The two long protrusions 712a and the four short protrusions 712b are provided at equal intervals (60-degree intervals) in the circumferential direction of the boom-side toothed portion 711D. The two long protrusions 712a are provided at diagonal positions. Two short protrusions 712b are provided at each of the positions sandwiched between the two long protrusions 712a in the circumferential direction. The number of long protrusions 712a may be one. In this case, the number of short protrusions 712b may be, for example, five.

[0281] The cylinder side clutch gear 8D also has a cylinder side tooth portion 811D. The cylinder side tooth portion 811D has a plurality of cylinder side protrusions 812D that are arranged side by side and spaced apart in the circumferential direction.

[0282] The cylinder side protrusion 812D has a long protrusion 812a and a short protrusion 812b. The long protrusion 812a is an example of a second long protrusion. The short protrusion 812b is an example of a second short protrusion. The axial length of the long protrusion 812a is longer than the axial length of the short protrusion 812b. In other words, the tip of the long protrusion 812a is closer to the motor side clutch gear 6D than the tip of the short protrusion 812b.

[0283] The long protrusions 812a are provided at two locations in the circumferential direction of the cylinder side toothed portion 811D. On the other hand, the short protrusions 812b are provided at four locations in the circumferential direction of the cylinder side toothed portion 811D. In other words, the cylinder side protrusions 812 have six protrusions. Note that the number of long protrusions 812a may be one. In this case, the number of short protrusions 812b may be, for example, five.

[0284] The two long protrusions 812a and the four short protrusions 812b are provided at equal intervals (60-degree intervals) in the circumferential direction of the cylinder-side toothed portion 811D. Two long protrusions 812a are provided diagonally opposite each other. Two short protrusions 812b are provided at positions sandwiched between two long protrusions 812a in the circumferential direction.

[0285] Here, the positional relationship between the motor side first long convex portion 611a and the motor side first short convex portion 611b of the motor side clutch gear 6D and the long convex portion 712a and the short convex portion 712b of the boom side clutch gear 7D will be described.

[0286] 9A , when the motor-side clutch gear 6D rotates in the direction indicated by arrow A4 in FIG. 9A (in other words, the second rotation direction), the cylinder coupling mechanism 45 is pulled out. At this time, the motor-side clutch gear 6D rotates a predetermined angle in the second rotation direction.

[0287] 9A (i.e., the state in which the cylinder coupling mechanism 45 is being disengaged), when the motor-side clutch gear 6D rotates a predetermined angle, the motor-side first long convex portion 611a of the motor-side clutch gear 6D and the long convex portion 712a of the boom-side clutch gear 7D do not interfere with each other in the circumferential direction. This configuration contributes to suppressing abnormal noise and damage to the gears.

[0288] 9A (i.e., the state in which the disengagement operation of the cylinder coupling mechanism 45 is being performed), when the motor-side clutch gear 6D rotates a predetermined angle, the motor-side first long convex portion 611a of the motor-side clutch gear 6D passes through the angular range in the circumferential direction in which the short convex portion 712b of the boom-side clutch gear 7D is provided. As a result, there is no interference in the circumferential direction between the motor-side first long convex portion 611a of the motor-side clutch gear 6D and the long convex portion 712a of the boom-side clutch gear 7D.

[0289] Furthermore, when the boom connecting mechanism 46 is operated, the switching mechanism 5D transitions from the state shown in Fig. 9A to the state shown in Fig. 9B. Specifically, the motor-side clutch gear 6D rotates in the direction indicated by arrow A3 in Fig. 9A based on the power of the electric motor 41. At this time, the cylinder-side clutch gear 8D does not rotate. The rotation direction of the electric motor 41 and the motor-side clutch gear 6D is the first rotation direction.

[0290] When the motor side clutch gear 6D rotates in the first rotation direction, the second inclined surface 6221 of the motor side second convex portion 622D (specifically, the motor side second long convex portion 622a) on the motor side clutch gear 6D is guided by the cylinder side inclined surface 8121 of the cylinder side convex portion 812D (specifically, the long convex portion 812a) on the cylinder side clutch gear 8D (in other words, pushed in the first direction), and the motor side clutch gear 6D moves in the direction of arrow A3 in Figure 9A (in other words, the first direction).

[0291] At this time, the amount of movement of the motor-side clutch gear 6D is equal to the height H2 (see FIG. 9A ) of the elongated protrusion 812a of the cylinder-side protrusion 812D. In this way, when the motor-side clutch gear 6D moves in the first direction by the height H2 of the elongated protrusion 812a, the motor-side clutch gear 6D engages with the boom-side clutch gear 7D. In this state, the switching mechanism 5D transitions to the state shown in FIG. 9B .

[0292] In this embodiment, the motor-side clutch gear 6D moves in the first direction with the motor-side second long protrusion 622a of the motor-side clutch gear 6D guided by the long protrusion 812a of the cylinder-side clutch gear 8D. This configuration ensures a large movement stroke of the motor-side clutch gear 6D. Therefore, in the state shown in Figure 9B, the motor-side clutch gear 6D can reliably engage with the boom-side clutch gear 7D.

[0293] 9B, when the motor-side clutch gear 6D rotates in the direction indicated by arrow A3 in FIG. 9B (in other words, the first rotation direction), the boom connecting mechanism 46 is pulled out. At this time, the motor-side clutch gear 6D rotates a predetermined angle in the first rotation direction.

[0294] 9B (i.e., the state in which the boom connecting mechanism 46 is being pulled out), when the motor-side clutch gear 6D rotates a predetermined angle, the motor-side second long protrusion 622a of the motor-side clutch gear 6D and the long protrusion 812a of the cylinder-side clutch gear 8D do not interfere with each other in the circumferential direction. This configuration contributes to suppressing abnormal noise and damage to the gears.

[0295] 9B (i.e., the state in which the boom connecting mechanism 46 is being pulled out), when the motor-side clutch gear 6D rotates a predetermined angle, the motor-side second long convex portion 622a of the motor-side clutch gear 6D passes through the angular range in which the short convex portion 812b of the cylinder-side clutch gear 8D is provided in the circumferential direction. As a result, there is no interference between the motor-side second long convex portion 622a of the motor-side clutch gear 6D and the long convex portion 812a of the cylinder-side clutch gear 8D in the circumferential direction. The rest of the configuration, functions, and effects of the mobile crane 1D are the same as those of the mobile crane 1C of the third embodiment described above.

[0296] Fifth Embodiment Next, a mobile crane 1E according to a fifth embodiment of the present invention will be described with reference to Fig. 10. Fig. 10 is a diagram showing the configuration of a switching mechanism 5E of a pin moving mechanism 4E incorporated in the mobile crane 1E.

[0297] The mobile crane 1E of this embodiment differs from the switching mechanism 5 of the mobile crane 1 according to the first embodiment in the configuration of the switching mechanism 5E. Below, we will explain the differences between the switching mechanism 5E and the switching mechanism 5. Note that the same components of the switching mechanism 5E as those of the switching mechanism 5 in the first embodiment are designated by the same reference numerals.

[0298] The switching mechanism 5E has a motor-side clutch gear 6E, a boom-side clutch gear 7E, and a cylinder-side clutch gear 8E. The configuration of the motor-side clutch gear 6E is the same as the configuration of the motor-side clutch gear 6 in the first embodiment.

[0299] The boom-side clutch gear 7E has a gear body 71 and a shaft portion 72E. The configuration of the gear body 71 is similar to the configuration of the gear body 71 in the first embodiment.

[0300] The shaft portion 72E is an example of a first shaft portion, and is provided integrally with the gear body 71. The shaft portion 72E is provided on the central axis of the gear body 71. The shaft portion 72E extends in the axial direction from the gear body 71 toward the motor-side clutch gear 6. The tip portion of the shaft portion 72E is spherical.

[0301] The shaft portion 72E is inserted into the through-hole 63 of the motor-side clutch gear 6. The outer diameter of the shaft portion 72E is slightly smaller than the outer diameter of the through-hole 63. Such a shaft portion 72E has the function of guiding the axial movement of the motor-side clutch gear 6. The shaft portion 72E also has the function of positioning the motor-side clutch gear 6 and the boom-side clutch gear 7E. Therefore, the shaft portion 72E contributes to improving the coaxiality between the motor-side clutch gear 6 and the boom-side clutch gear 7E.

[0302] The cylinder-side clutch gear 8E is an example of a second shaft portion, and includes a gear body 81 and a shaft portion 82E. The configuration of the gear body 81 is similar to the configuration of the gear body 81 in the first embodiment.

[0303] The shaft portion 82E is an example of a first shaft portion, and is provided integrally with the gear body 81. The shaft portion 82E is provided on the central axis of the gear body 81. The shaft portion 82E extends in the axial direction from the gear body 81 toward the motor-side clutch gear 6. The tip portion of the shaft portion 82E is spherical.

[0304] The shaft portion 82E is inserted into the through-hole 63 of the motor-side clutch gear 6. The outer diameter of the shaft portion 82E is slightly smaller than the outer diameter of the through-hole 63. Such a shaft portion 82E has the function of guiding the axial movement of the motor-side clutch gear 6. The shaft portion 82E also has the function of positioning the motor-side clutch gear 6 and the cylinder-side clutch gear 8E. Therefore, the shaft portion 82E contributes to improving the coaxiality between the motor-side clutch gear 6 and the cylinder-side clutch gear 8E.

[0305] Furthermore, the tip of the shaft 72E of the boom-side clutch gear 7E and the tip of the shaft 82E of the cylinder-side clutch gear 8E face each other in the axial direction, either in contact or with a small gap between them, within the through-hole 63. This configuration contributes to reducing sliding resistance when the tip of the shaft 72E and the tip of the shaft 82E come into contact with each other during operation of the switching mechanism 5E.

[0306] FIG. 11 is a diagram showing an example of a modified switching mechanism 5E according to this embodiment. As in the switching mechanism 5E1 shown in FIG. 11 , a ball 74 may be provided between the tip of the shaft 82E1 and the tip of the shaft 72E1. The ball 74 may be made of metal or synthetic resin. This configuration also contributes to reducing sliding resistance when the tip of the shaft 72E contacts the ball 74 or when the tip of the shaft 82E1 contacts the ball 74 during operation of the switching mechanism 5E1. The rest of the configuration, operation, and effects of the mobile crane 1E are the same as those of the mobile crane 1 according to the first embodiment.

[0307] Sixth Embodiment Next, a mobile crane 1F according to a sixth embodiment of the present invention will be described with reference to Figures 12A and 12B. For the configurations of the cylinder coupling mechanism 45 and the boom coupling mechanism 46, please refer to Figures 3A to 3C and 4A to 4C.

[0308] 12A and 12B are diagrams showing the configuration of a switching mechanism 5F of a pin moving mechanism 4F incorporated in a mobile crane 1F.

[0309] In the mobile crane 1F of this embodiment, the configuration of the switching mechanism 5F differs from the configuration of the switching mechanism 5 of the mobile crane 1 according to the above-described embodiment 1. The configuration of the switching mechanism 5F will be described below.

[0310] The operation of the cylinder coupling mechanism 45 and the boom coupling mechanism 46 is similar to that of the cylinder coupling mechanism 45 and the boom coupling mechanism 46 of the mobile crane 1 according to the above-described embodiment 1. Therefore, with regard to the configuration and operation of the cylinder coupling mechanism 45 and the boom coupling mechanism 46, explanations that overlap with those of the above-described embodiment 1 will be omitted.

[0311] The switching mechanism 5F selectively engages with one of the cylinder connecting mechanism 45 and the boom connecting mechanism 46, and transmits the power of the electric motor 41 to the other connecting mechanism. The switching mechanism 5F has a motor-side clutch gear 6F, a boom-side clutch gear 7F, and a cylinder-side clutch gear 8F.

[0312] The configurations of the motor side clutch gear 6F, boom side clutch gear 7F, and cylinder side clutch gear 8F are substantially the same as the configurations of the motor side clutch gear 6C, boom side clutch gear 7C, and cylinder side clutch gear 8C in the above-described third embodiment.

[0313] Therefore, among the configurations of the motor side clutch gear 6F, boom side clutch gear 7F, and cylinder side clutch gear 8F, the same configurations as the motor side clutch gear 6C, boom side clutch gear 7C, and cylinder side clutch gear 8C in the above-mentioned third embodiment are given the same symbols as the motor side clutch gear 6C, boom side clutch gear 7C, and cylinder side clutch gear 8C in the third embodiment.

[0314] For the configurations of the motor side clutch gear 6F, boom side clutch gear 7F, and cylinder side clutch gear 8F, the descriptions of the motor side clutch gears 6, 6C, boom side clutch gears 7, 7C, and cylinder side clutch gears 8, 8C in the first and third embodiments may be used as appropriate.

[0315] In this embodiment, the motor-side clutch gear 6F has clutch-side teeth 64 on its outer circumferential surface. The clutch-side teeth 64 are integrally formed with the motor-side clutch gear 6F. The clutch-side teeth 64 are formed over the entire outer circumferential surface of the motor-side clutch gear 6F. The clutch-side teeth 64 are preferably spur teeth. However, the clutch-side teeth 64 may also be helical teeth.

[0316] The clutch-side teeth portion 64 is connected to the transmission mechanism 43. Specifically, the clutch-side teeth portion 64 meshes with a transmission gear 433 fixed to a transmission shaft 432 in the transmission mechanism 43. The transmission gear 433 is a gear that can mesh with the transmission gear 433.

[0317] When the transmission gear 433 rotates based on the power of the electric motor 41, the rotation of the transmission gear 433 is transmitted to the clutch-side tooth portion 64. Then, the motor-side clutch gear 6F rotates. The motor-side clutch gear 6F is movable in the axial direction relative to the transmission gear 433.

[0318] The rest of the configuration of the motor-side clutch gear 6F is the same as the configuration of the motor-side clutch gear 6C in embodiment 3. Furthermore, the configuration of the boom-side clutch gear 7F is the same as the configuration of the boom-side clutch gear 7C in embodiment 3. Furthermore, the configuration of the cylinder-side clutch gear 8F is the same as the configuration of the cylinder-side clutch gear 8C in embodiment 3.

[0319] 12A and 12B are diagrams showing the state of the switching mechanism 5F when the boom connection mechanism 46 performs the retracting operation and the retracting operation. Hereinafter, the operation of the switching mechanism 5F will be described with reference to FIGS. 12A and 12B.

[0320] 12A shows the initial state of the switching mechanism 5F. In the initial state of the switching mechanism 5F, the motor-side clutch gear 6F, the boom-side clutch gear 7F, and the cylinder-side clutch gear 8F are all in their initial positions. In the initial state of the switching mechanism 5F (in other words, the second position), the motor-side clutch gear 6F is engaged with the cylinder-side clutch gear 8F.

[0321] The state of the switching mechanism 5F shown in FIG. 12A is also the state of the switching mechanism 5F before the boom connection mechanism 46 performs the retracting operation of the boom connection mechanism 46.

[0322] When the boom connection mechanism 46 performs the retracting operation of the boom connection mechanism 46, a control unit (not shown) turns on the electric motor 41. Then, the control unit drives the electric motor 41 in a first rotation direction. The power (rotation) of the electric motor 41 is transmitted to the motor-side clutch gear 6F via the transmission mechanism 43.

[0323] Specifically, the power (rotation) of the electric motor 41 is transmitted in the following order: electric motor 41, reducer 431, transmission shaft 432, transmission gear 433, clutch-side tooth portion 64, and motor-side clutch gear 6F. Then, the motor-side clutch gear 6F rotates in the direction of arrow A3 in Fig. 12A. The rotation direction of the motor-side clutch gear 6F at this time is referred to as a first rotation direction of the motor-side clutch gear 6F.

[0324] When the motor side clutch gear 6F rotates in the first rotation direction, the second inclined surface 6221 of the motor side second convex portion 622 on the motor side clutch gear 6F is guided by the cylinder side inclined surface 8121 of the cylinder side convex portion 812 on the cylinder side clutch gear 8F (in other words, pushed in the first direction), and the motor side clutch gear 6F moves in the direction of arrow A1 in Figure 12A (in other words, the first direction).

[0325] At this time, the amount of movement of the motor-side clutch gear 6F is equal to the height H1 of the cylinder-side protrusion 812 (see FIG. 12A). When the motor-side clutch gear 6F moves in the first direction by the height H1 of the cylinder-side protrusion 812, the motor-side clutch gear 6F engages with the boom-side clutch gear 7F (see FIG. 12B). In the switching mechanism 5F in the state shown in FIG. 12B, the position of the motor-side clutch gear 6F is the first position.

[0326] Thus, in the case of this embodiment, when the motor-side clutch gear 6F rotates in the first rotational direction in the second connected state in which the power of the electric motor 41 can be transmitted to the cylinder-side clutch gear 8F, it is guided by the cylinder-side clutch gear 8F (in other words, the second transmission member) and moves to a first position (the position of the motor-side clutch gear 6F in Figure 12B) corresponding to the first connected state in which the power of the electric motor 41 can be transmitted to the boom-side clutch gear 7F (in other words, the first transmission member).

[0327] As described above, the switching mechanism 5F of this embodiment does not have a clutch actuator for axially moving the motor-side clutch gear 6F. In other words, in the case of the switching mechanism 5F of this embodiment, the electric motor 41 functions as the clutch actuator (i.e., the drive unit).

[0328] In the state shown in Figure 12B, the switching mechanism 5F is in the first coupled state. In the first coupled state of the switching mechanism 5F, the motor-side clutch gear 6F is engaged with the boom-side clutch gear 7F. The state of the switching mechanism 5F shown in Figure 12A is referred to as the second coupled state.

[0329] In the state shown in FIG. 12B, the motor-side first tooth portion 61 of the motor-side clutch gear 6F engages with the boom-side tooth portion 711 of the boom-side clutch gear 7F.

[0330] The first coupled state of the switching mechanism 5F is a state in which rotation of the motor-side clutch gear 6F can be transmitted to the boom-side clutch gear 7F. In the first coupled state of the switching mechanism 5F, the motor-side first convex portion 611 of the motor-side first tooth portion 61 of the motor-side clutch gear 6F and the boom-side convex portion 712 of the boom-side tooth portion 711 of the boom-side clutch gear 7F are engaged in the circumferential direction.

[0331] Furthermore, in the first connected state of the switching mechanism 5F, the first inclined surface 6111 of the motor side clutch gear 6F and the boom side inclined surface 7121 of the boom side clutch gear 7F engage (specifically, abut) while facing each other in the axial direction.

[0332] Next, in the state shown in Fig. 12B, the control unit (not shown) further drives the electric motor 41 in the first rotational direction. As a result, the motor-side clutch gear 6F further rotates in the first rotational direction. The power (rotation) of the electric motor 41 is transmitted from the motor-side clutch gear 6F to the boom-side clutch gear 7F. In addition, the rotation of the boom-side clutch gear 7F is transmitted to the boom connection mechanism 46 (see Fig. 4A).

[0333] As a result, the boom connection mechanism 46 transitions from the extended state (the state shown in FIG. 4A) to the retracted state (the state shown in FIG. 4C). In this state, the control unit (not shown) turns on the brake mechanism 42. Thereafter, the control unit (not shown) turns off the electric motor 41. The retracted state of the boom connection mechanism 46 is then maintained.

[0334] Next, in the state shown in Fig. 12B, the boom connection mechanism 46 performs the retracting operation of the boom connection mechanism 46. The retracting operation of the boom connection mechanism 46 is performed automatically based on the biasing force of the second biasing mechanism 463 (see Fig. 4A).

[0335] Specifically, in the state of the switching mechanism 5F shown in Fig. 12B, the boom side clutch gear 7F rotates in the direction indicated by arrow A4 in Fig. 12B based on the biasing force of the second biasing mechanism 463. The rotation direction at this time is the second rotation direction.

[0336] When the boom-side clutch gear 7F rotates a predetermined amount, the boom-side clutch gear 7F and the motor-side clutch gear 6F stop rotating in the second rotation direction. The boom connection mechanism 46 then transitions from the contracted state (the state shown in FIG. 4C ) to the extended state (the state shown in FIG. 4A ). In this state, the boom connection pin 144a is in the engaged state.

[0337] When the cylinder coupling mechanism 45 is removed from the state shown in Fig. 12B, the control unit (not shown) drives the electric motor 41 in the second rotation direction, causing the motor-side clutch gear 6F to rotate in the direction indicated by the arrow A4 in Fig. 12B.

[0338] When the motor side clutch gear 6F rotates in the second rotation direction, the first inclined surface 6111 of the motor side first convex portion 611 on the motor side clutch gear 6F is guided by the boom side inclined surface 7121 of the boom side convex portion 712 on the boom side clutch gear 7F (in other words, pushed in the second direction), and the motor side clutch gear 6F moves in the direction of arrow A2 in Figure 12A (in other words, the second direction).

[0339] Thus, in the case of this embodiment, when the motor-side clutch gear 6F rotates in the second rotation direction in the first connected state in which the power of the electric motor 41 can be transmitted to the boom-side clutch gear 7F, it is guided by the boom-side clutch gear 7F (in other words, the first transmission member) and moves to the second position (the position of the motor-side clutch gear 6F in FIG. 12A ) corresponding to the second connected state in which the power of the electric motor 41 can be transmitted to the cylinder-side clutch gear 8F (in other words, the second transmission member). Then, the motor-side clutch gear 6F engages with the cylinder-side clutch gear 8F.

[0340] Then, the control unit (not shown) further drives the electric motor 41 in the second rotation direction. As a result, the motor-side clutch gear 6F further rotates in the direction indicated by arrow A4 in Fig. 12A. At this time, the rotation direction of the motor-side clutch gear 6F and the electric motor 41 is the second rotation direction.

[0341] When the motor-side clutch gear 6F rotates in the second rotational direction, the cylinder-side clutch gear 8F rotates in the second rotational direction. The rotation of the cylinder-side clutch gear 8F is then transmitted to the cylinder coupling mechanism 45. As a result, the cylinder coupling mechanism 45 transitions from the expanded state (see FIG. 3A) to the contracted state (see FIG. 3C). The engaging operation of the cylinder coupling mechanism 45 is performed automatically based on the biasing force of the first biasing mechanism 455.

[0342] In the case of the mobile crane 1F according to this embodiment having the above-described configuration, the electric motor 41 functions as a clutch actuator that moves the motor-side clutch gear 6F of the switching mechanism 5F. This configuration contributes to the miniaturization of the switching mechanism 5F.

[0343] Seventh Embodiment Next, a mobile crane 1G according to a seventh embodiment of the present invention will be described with reference to Figures 13A and 13B. In addition, for the configurations of the cylinder coupling mechanism 45 and the boom coupling mechanism 46, reference will be made to Figures 3A to 3C and 4A to 4C.

[0344] 13A and 13B are diagrams showing the configuration of a switching mechanism 5G of a pin moving mechanism 4G incorporated in a mobile crane 1G.

[0345] The mobile crane 1G of this embodiment has a switching mechanism 5G whose configuration differs from the switching mechanism 5F of the mobile crane 1F of the above-described embodiment 6. The configuration of the switching mechanism 5G will be described below.

[0346] The operation of the cylinder coupling mechanism 45 and the boom coupling mechanism 46 is similar to that of the cylinder coupling mechanism 45 and the boom coupling mechanism 46 of the mobile crane 1 according to the above-described embodiment 1. Therefore, with regard to the configuration and operation of the cylinder coupling mechanism 45 and the boom coupling mechanism 46, explanations that overlap with those of the above-described embodiment 1 will be omitted.

[0347] The switching mechanism 5G selectively engages with one of the cylinder connecting mechanism 45 and the boom connecting mechanism 46 to transmit the power of the electric motor 41 to the other connecting mechanism. The switching mechanism 5G has a motor-side clutch gear 6G, a boom-side clutch gear 7G, and a cylinder-side clutch gear 8G. The switching mechanism 5G also has a sleeve portion 66G.

[0348] The configurations of the motor side clutch gear 6G, boom side clutch gear 7G, and cylinder side clutch gear 8G are substantially the same as the configurations of the motor side clutch gear 6F, boom side clutch gear 7F, and cylinder side clutch gear 8F in the sixth embodiment.

[0349] In this embodiment, the clutch-side teeth 64 provided on the outer peripheral surface of the motor-side clutch gear 6G are male splines.

[0350] The sleeve portion 66G is cylindrical. The sleeve portion 66G has a female spline on its inner circumferential surface. The sleeve portion 66G has teeth on its outer circumferential surface. The sleeve portion 66G is fixed to a fixed portion (not shown). The sleeve portion 66G is rotatable. However, the axial movement of the sleeve portion 66G is restricted by the fixed portion (not shown).

[0351] The motor-side clutch gear 6G is inserted into the sleeve portion 66G. In other words, the sleeve portion 66G covers the outer peripheral surface of the motor-side clutch gear 6G. In this state, the female splines of the sleeve portion 66G mesh with the clutch-side teeth 64 of the motor-side clutch gear 6G.

[0352] The motor-side clutch gear 6G is movable in the axial direction relative to the sleeve portion 66G. When the sleeve portion 66G rotates, the rotation of the sleeve portion 66G is transmitted to the motor-side clutch gear 6G.

[0353] The teeth provided on the outer peripheral surface of the sleeve portion 66G mesh with a transmission gear 433 fixed to a transmission shaft 432 in the transmission mechanism 43. The transmission gear 433 is a gear that can mesh with the teeth provided on the outer peripheral surface of the sleeve portion 66G.

[0354] When the transmission gear 433 rotates based on the power of the electric motor 41, the rotation of the transmission gear 433 is transmitted to the sleeve portion 66G. The rotation of the sleeve portion 66G is then transmitted to the motor-side clutch gear 6F. As a result, the motor-side clutch gear 6G rotates.

[0355] The rest of the configuration of the motor-side clutch gear 6G is the same as the configuration of the motor-side clutch gear 6F in embodiment 6. Also, the configuration of the boom-side clutch gear 7G is the same as the configuration of the boom-side clutch gear 7F in embodiment 6. Also, the configuration of the cylinder-side clutch gear 8G is the same as the configuration of the cylinder-side clutch gear 8F in embodiment 6.

[0356] 13A and 13B are diagrams showing the state of the switching mechanism 5G when the boom connecting mechanism 46 performs the retracting operation and the retracting operation. Hereinafter, the operation of the switching mechanism 5G will be described with reference to FIGS. 13A and 13B.

[0357] 13A shows the initial state of the switching mechanism 5G. In the initial state of the switching mechanism 5G, the motor-side clutch gear 6G, the boom-side clutch gear 7G, and the cylinder-side clutch gear 8G are all in their initial positions. In the initial state of the switching mechanism 5G (in other words, the second position), the motor-side clutch gear 6G is engaged with the cylinder-side clutch gear 8G.

[0358] The state of the switching mechanism 5G shown in FIG. 13A is also the state of the switching mechanism 5G before the boom connection mechanism 46 performs the retracting operation of the boom connection mechanism 46.

[0359] When the boom connection mechanism 46 performs the retracting operation of the boom connection mechanism 46, a control unit (not shown) turns on the electric motor 41. Then, the control unit drives the electric motor 41 in a first rotation direction. The power (rotation) of the electric motor 41 is transmitted to the motor-side clutch gear 6G via the transmission mechanism 43.

[0360] Specifically, the power (rotation) of the electric motor 41 is transmitted in the following order: electric motor 41, reducer 431, transmission shaft 432, transmission gear 433, sleeve portion 66G, clutch-side tooth portion 64, and motor-side clutch gear 6G. Then, the motor-side clutch gear 6G rotates in the direction of arrow A3 in Fig. 13A. The rotation direction of the motor-side clutch gear 6G at this time is referred to as a first rotation direction of the motor-side clutch gear 6G.

[0361] When the motor side clutch gear 6G rotates in the first rotation direction, the second inclined surface 6221 of the motor side second convex portion 622 on the motor side clutch gear 6G is guided by the cylinder side inclined surface 8121 of the cylinder side convex portion 812 on the cylinder side clutch gear 8G (in other words, pushed in the first direction).

[0362] In this embodiment, the motor-side clutch gear 6G is movable in the axial direction relative to the sleeve portion 66G. Therefore, the motor-side clutch gear 6G moves in the direction of arrow A1 in Figure 13A (in other words, the first direction).

[0363] At this time, the amount of movement of the motor-side clutch gear 6F is equal to the height H1 of the cylinder-side protrusion 812 (see FIG. 13A). In this way, when the motor-side clutch gear 6G moves in the first direction by the height H1 of the cylinder-side protrusion 812, the motor-side clutch gear 6G engages with the boom-side clutch gear 7G (see FIG. 13B). In the switching mechanism 5G in the state shown in FIG. 13B, the position of the motor-side clutch gear 6G is the first position.

[0364] Thus, in the case of this embodiment, when the motor-side clutch gear 6G rotates in the first rotational direction in the second connected state in which the power of the electric motor 41 can be transmitted to the cylinder-side clutch gear 8G, it is guided by the cylinder-side clutch gear 8G (in other words, the second transmission member) and moves to a first position (the position of the motor-side clutch gear 6G in Figure 13B) corresponding to the first connected state in which the power of the electric motor 41 can be transmitted to the boom-side clutch gear 7G (in other words, the first transmission member).

[0365] As described above, the switching mechanism 5G of this embodiment does not have a clutch actuator for axially moving the motor-side clutch gear 6G. In other words, in the case of the switching mechanism 5G of this embodiment, the electric motor 41 functions as the clutch actuator (i.e., the drive unit).

[0366] In the state shown in Figure 13B, the switching mechanism 5G is in the first coupled state. In the first coupled state of the switching mechanism 5G, the motor-side clutch gear 6G is engaged with the boom-side clutch gear 7G. The state of the switching mechanism 5G shown in Figure 13A is referred to as the second coupled state.

[0367] In the state shown in FIG. 13B, the motor-side first tooth portion 61 of the motor-side clutch gear 6G engages with the boom-side tooth portion 711 of the boom-side clutch gear 7G.

[0368] The first coupled state of the switching mechanism 5G is a state in which rotation of the motor-side clutch gear 6G can be transmitted to the boom-side clutch gear 7G. In the first coupled state of the switching mechanism 5G, the motor-side first convex portion 611 of the motor-side first tooth portion 61 of the motor-side clutch gear 6G and the boom-side convex portion 712 of the boom-side tooth portion 711 of the boom-side clutch gear 7G are engaged in the circumferential direction.

[0369] Furthermore, in the first connected state of the switching mechanism 5G, the first inclined surface 6111 of the motor side clutch gear 6G and the boom side inclined surface 7121 of the boom side clutch gear 7G engage (specifically, abut) while facing each other in the axial direction.

[0370] Next, in the state shown in Figure 13B, the control unit (not shown) further drives the electric motor 41 in the first rotational direction. This causes the motor-side clutch gear 6G to further rotate in the first rotational direction. The power (rotation) of the electric motor 41 is transmitted from the motor-side clutch gear 6G to the boom-side clutch gear 7G. In addition, the rotation of the boom-side clutch gear 7G is transmitted to the boom connecting mechanism 46 (see Figure 4A).

[0371] As a result, the boom connection mechanism 46 transitions from the extended state (the state shown in FIG. 4A) to the retracted state (the state shown in FIG. 4C). In this state, the control unit (not shown) turns on the brake mechanism 42. Thereafter, the control unit (not shown) turns off the electric motor 41. The retracted state of the boom connection mechanism 46 is then maintained.

[0372] Next, in the state shown in Fig. 13B, the boom connection mechanism 46 performs the retracting operation of the boom connection mechanism 46. The retracting operation of the boom connection mechanism 46 is performed automatically based on the biasing force of the second biasing mechanism 463 (see Fig. 4A).

[0373] Specifically, in the state of the switching mechanism 5G shown in Fig. 13B, the boom side clutch gear 7G rotates in the direction indicated by arrow A4 in Fig. 13B based on the biasing force of the second biasing mechanism 463. The rotation direction at this time is the second rotation direction.

[0374] When the boom-side clutch gear 7G rotates a predetermined amount, the boom-side clutch gear 7G and the motor-side clutch gear 6G stop rotating in the second rotation direction. The boom connection mechanism 46 then transitions from the contracted state (the state shown in FIG. 4C ) to the extended state (the state shown in FIG. 4A ). In this state, the boom connection pin 144a is in the engaged state.

[0375] 13B, when the cylinder coupling mechanism 45 is to be removed, the control unit (not shown) drives the electric motor 41 in the second rotation direction. The rotation of the electric motor 41 is transmitted in the following order: electric motor 41, reducer 431, transmission shaft 432, transmission gear 433, sleeve 66, clutch-side toothed portion 64, and motor-side clutch gear 6G. As a result, the motor-side clutch gear 6G rotates in the direction indicated by arrow A4 in FIG. 12B.

[0376] When the motor side clutch gear 6G rotates in the second rotation direction, the first inclined surface 6111 of the motor side first convex portion 611 on the motor side clutch gear 6G is guided by the boom side inclined surface 7121 of the boom side convex portion 712 on the boom side clutch gear 7G (in other words, pushed in the second direction), and the motor side clutch gear 6G moves in the direction of arrow A2 in Figure 13A (in other words, the second direction).

[0377] Thus, in the case of this embodiment, when the motor-side clutch gear 6G rotates in the second rotation direction in the first connected state in which the power of the electric motor 41 can be transmitted to the boom-side clutch gear 7G, it is guided by the boom-side clutch gear 7G (in other words, the first transmission member) and moves to the second position (the position of the motor-side clutch gear 6G in FIG. 13A ) corresponding to the second connected state in which the power of the electric motor 41 can be transmitted to the cylinder-side clutch gear 8G (in other words, the second transmission member). Then, the motor-side clutch gear 6G engages with the cylinder-side clutch gear 8G.

[0378] Then, the control unit (not shown) further drives the electric motor 41 in the second rotation direction. As a result, the motor-side clutch gear 6G further rotates in the direction indicated by arrow A4 in Fig. 13A. At this time, the rotation direction of the motor-side clutch gear 6G and the electric motor 41 is the second rotation direction.

[0379] When the motor-side clutch gear 6G rotates in the second rotational direction, the cylinder-side clutch gear 8G rotates in the second rotational direction. The rotation of the cylinder-side clutch gear 8G is then transmitted to the cylinder coupling mechanism 45. As a result, the cylinder coupling mechanism 45 transitions from the expanded state (see FIG. 3A) to the contracted state (see FIG. 3C). The engaging operation of the cylinder coupling mechanism 45 is performed automatically based on the biasing force of the first biasing mechanism 455.

[0380] In the case of the mobile crane 1G according to this embodiment having the above-described configuration, the electric motor 41 functions as a clutch actuator that moves the motor-side clutch gear 6G of the switching mechanism 5G. This configuration contributes to the miniaturization of the switching mechanism 5G.

[0381] <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.

[0382] The disclosures of the specification, drawings, and abstract contained in Japanese Patent Application No. 2023-217187, filed December 22, 2023, are incorporated herein by reference in their entirety.

[0383] 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.

[0384] 1, 1B, 1C, 1D, 1E, 1F, 1G Mobile crane 10 Traveling body 12 Swivel base 14 Telescopic boom 141 Tip boom 1411, 1412 Cylinder pin receiving portion 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 143 Base boom 144a, 144b Boom connecting pin 16 Wire rope 17 Hook 2 Actuator 3 Telescopic cylinder 31 Rod member 32 Cylinder member 4, 4B, 4C, 4D, 4E, 4F, 4G Pin moving mechanism 41 Electric motor 42 Brake mechanism 43 Transmission mechanism 431 Reducer 432 Transmission shaft 433 Transmission gear 44 Position information detection device 45 Cylinder coupling mechanism 451 First rack bar 452 First gear mechanism 453 Second gear mechanism 454A, 454B Cylinder coupling pin 455 First biasing mechanism 455a, 455b Coil spring 46 Boom coupling mechanism 461a, 461b Second rack bar 461g, 461h Locking claw portion 462 Synchronous gear 463 Second biasing mechanism 463a, 463b Coil spring 5, 5B, 5C, 5D, 5E, 5E1, 5F, 5G Switching mechanism 6, 6B, 6C, 6D, 6E, 6G, 6F Motor side clutch gear 6a First gear element 6b Second gear element 6c Connecting shaft portion 61, 61B, 61D Motor side first tooth portion 611, 611D Motor side first convex portion 6111 First inclined surface 611a Motor side first long convex portion 611b Motor side first short convex portion 62, 62B, 62D Motor side second tooth portion 622, 622D Motor side second convex portion 6221 Second inclined surface 622a Motor side second long convex portion 622b Motor side second short convex portion 63 Through hole 64 Clutch side tooth portion 66G Sleeve portion 7, 7B, 7C, 7D, 7E, 7F, 7G Boom side clutch gear 71 Gear body 711 Boom side tooth portion 712 Boom side convex portion 7121 Boom side inclined surface 712a Long convex portion 712b Short convex portion 72, 72E, 72E1 Shaft portion 73, 73B Boom side pinion gear 74 Ball8, 8B, 8C, 8D, 8E, 8F, 8G Cylinder side clutch gear 81, 81B Gear body 811 Cylinder side tooth portion 812 Cylinder side convex portion 8121 Cylinder side inclined surface 812a Long convex portion 812b Short convex portion 82, 82E, 82E1 Shaft portion 83, 83B Cylinder side pinion gear 9 Clutch actuator 91a First drive portion 92a First spring 93a First pressing portion 930a Through hole 91b Second drive portion 92b Second spring 93b Second pressing portion 930b Through hole 99 Fixing portion

Claims

1. A work machine comprising: a telescopic boom having multiple booms that are extended and retracted by a telescopic cylinder; a first connecting mechanism that connects the booms to the telescopic cylinders and releases the connection by a motor; a second connecting mechanism that connects adjacent booms to each other and releases the connection by the motor; and a switching mechanism having a motor-side transmission member that moves axially to be selectively connected to one of the first and second connecting mechanisms and transmits the power of the motor to the one connecting mechanism.

2. A work machine as described in claim 1, wherein the rotation direction of the motor when the power is transmitted to the first connecting mechanism is the same as the rotation direction of the motor when the power is transmitted to the second connecting mechanism.

3. The work machine according to claim 1, wherein the rotation direction of the motor when the power is transmitted to the first connecting mechanism is opposite to the rotation direction of the motor when the power is transmitted to the second connecting mechanism.

4. A work machine as described in claim 1, wherein the switching mechanism further has a first transmission member connected to the first connecting mechanism and a second transmission member connected to the second connecting mechanism, and the motor-side transmission member engages with the first transmission member in a first state in which the power is transmitted to the first connecting mechanism, and engages with the second transmission member in a second state in which the power is transmitted to the second connecting mechanism.

5. The work machine according to claim 4, wherein the first transmission member, the second transmission member, and the motor-side transmission member are arranged on the same straight line.

6. A work machine as described in claim 4, wherein the motor-side transmission member engages with the first transmission member at a first position, engages with the second transmission member at a second position, and does not engage with either the first transmission member or the second transmission member at a third position between the first position and the second position.

7. A work machine as described in claim 4, wherein the motor-side transmission member and the first transmission member are configured to be able to transmit the power only when the first transmission member rotates in a predetermined direction, and the motor-side transmission member and the second transmission member are configured to be able to transmit the power only when the second transmission member rotates in a predetermined direction.

8. The work machine according to claim 4, wherein, when the motor-side transmission member rotates in the second state, it is guided by the second transmission member to move to a first position corresponding to the first state, and when the motor-side transmission member rotates in the first state, it is guided by the first transmission member to move to a second position corresponding to the second state.

9. A work machine as described in claim 8, wherein the motor side transmission member has a plurality of motor side first tooth portions and a plurality of motor side second tooth portions, the first transmission member has first tooth portions that engage with the motor side first tooth portions in the first state, and the second transmission member has second tooth portions that engage with the motor side second tooth portions in the second state.

10. The working machine according to claim 9, wherein the motor-side first tooth portion has a motor-side first short convex portion and a motor-side first long convex portion having a length in the axial direction longer than that of the motor-side first short convex portion, the motor-side second tooth portion has a motor-side second short convex portion and a motor-side second long convex portion having a length in the axial direction longer than that of the motor-side second short convex portion, the first tooth portions have a first short convex portion and a first long convex portion having a length in the axial direction longer than that of the first short convex portion, the second tooth portions have a second short convex portion and a second long convex portion having a length in the axial direction longer than that of the second short convex portion, and the motor-side transmission member moves to the first position by being guided by the second long convex portion, and the motor-side first long convex portion moves to the second position by being guided by the first long convex portion.

11. A work machine as described in claim 10, wherein in the first state, within an angular range in which the motor side transmission member rotates, the motor side second long convex portion and the second long convex portion do not interfere with each other, and in the second state, within an angular range in which the motor side transmission member rotates, the motor side first long convex portion and the first long convex portion do not interfere with each other.

12. The work machine described in claim 5, wherein the first transmission member has a spherical tip surface and a first shaft portion inserted into the motor side transmission member, the second transmission member has a spherical tip surface and a second shaft portion inserted into the motor side transmission member, and the tip surface of the first shaft portion and the tip surface of the second shaft portion face each other in a state capable of contacting each other within the motor side transmission member.

13. A work machine as described in claim 4, further comprising a ball provided within the motor side transmission member, wherein the first transmission member has a first shaft portion inserted into the motor side transmission member, and the second transmission member has a second shaft portion inserted into the motor side transmission member, and a tip surface of the first shaft portion and a tip surface of the second shaft portion face each other within the motor side transmission member and are in contact with the ball.

14. The work machine according to claim 1, further comprising a drive unit that moves the motor-side transmission member in the axial direction.

15. A work machine as described in claim 14, wherein the drive unit has an actuator that generates power in the axial direction, and an elastic member that transmits the power of the actuator to the motor-side transmission member, and the elastic member biases the motor-side transmission member toward one of the connecting mechanisms when the power of the motor is capable of being transmitted to one of the connecting mechanisms.

16. The work machine according to claim 1, wherein the motor functions as a drive unit that moves the motor-side transmission member in the axial direction.

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