Work machine

Abstract

To provide a work machine capable of improving degree of freedom in design around an extendable boom.SOLUTION: A work machine comprises an extendable boom having a plurality of booms and extending and retracting by means of an extension cylinder, a first connecting mechanism connecting the boom and the extension cylinder and releasing the connection by means of a motor, a second connecting mechanism connecting adjacent booms and releasing the connection by means of a motor, and a switching mechanism selectively connected to one of the first connecting mechanism and the second connecting mechanism by moving in an axial direction and having a motor side transmission member that transmits the motor's power to one of the connecting mechanisms.SELECTED DRAWING: Figure 5A

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a mobile crane including a telescopic boom in which a plurality of booms are nested and a hydraulic actuator (telescopic cylinder) for extending the telescopic boom.

[0003] Adjacent booms are connected by boom connection pins. The boom whose connection by the boom connection pins is released (hereinafter referred to as a movable boom) is movable in the telescopic direction with respect to other booms.

[0004] Further, the actuator is connected to the movable boom via a cylinder connection pin. When the actuator moves in the telescopic direction in this state, the movable boom moves together with the actuator, and the telescopic boom expands and contracts.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, a crane as described above includes a hydraulic actuator for displacing a boom connection pin, a hydraulic actuator for displacing a cylinder connection pin, and a hydraulic circuit for supplying pressure oil to each of these actuators. Such a hydraulic circuit is provided, for example, around the telescopic boom. For this reason, there is a possibility that the degree of freedom in design around the telescopic boom may decrease.

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

Means for Solving the Problems

[0008] One aspect of the working machine according to the present invention is a telescopic boom having a plurality of booms and telescoping by a telescopic cylinder, a first coupling mechanism that couples the boom and the telescopic cylinder and releases the coupling by a motor, a second coupling mechanism that couples adjacent booms and releases the coupling by a motor, a switching mechanism that moves in the axial direction and is selectively connected to one of the first coupling mechanism and the second coupling mechanism and has a motor-side transmission member that transmits the power of the motor to one of the coupling mechanisms.

Effects of the Invention

[0009] According to the present invention, it is possible to provide a working machine capable of improving the degree of freedom in design around a telescopic boom.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 2E

Figure 3A

Figure 3B

Figure 3C

Figure 4A

Figure 4B

Figure 4C

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 7A

Figure 7B

Figure 7C

Figure 8A

Figure 8B

Figure 9A

Figure 9B

Figure 10

Figure 11

Figure 12A

Figure 12B

Figure 13A

Figure 13B

Mode for Carrying Out the Invention

[0011] Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. Note that the crane according to the embodiment described below is an example of a working machine according to the present invention, and the present invention is not limited by the embodiment described below.

[0012] [Embodiment 1] With reference to FIGS. 1 to 6B, the mobile crane 1 according to Embodiment 1 of the present invention will be described. First, with reference to FIGS. 1 and 2A to 2E, the outline of the mobile crane 1 according to Embodiment 1 of the present invention will be described.

[0013] Examples of the mobile crane include a rough terrain crane, an all terrain crane, a truck crane, or a loading truck crane. However, the working machine is not limited to a mobile crane, and may be other working machines (for example, an aerial work platform) having 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 in a telescopic manner. Adjacent booms are connected by boom connection pins (boom connection pins 144a, 144b).

[0015] When the actuator 2 extends and retracts the telescopic boom 14, the actuator 2 moves the boom in the extending and retracting direction. At this time, the actuator 2 is connected to the boom to be moved via cylinder connection pins 454A and 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 has a traveling body 10, a slewing platform 12, a telescopic boom 14, an actuator 2, a wire rope 16, and a hook 17.

[0017] The slewing platform 12 is rotatably provided on the upper part of the traveling body 10. The telescopic boom 14 has a plurality of booms (for example, a tip boom 141, an intermediate boom 142, and a base boom 143 described later), and expands and contracts by an expansion and contraction cylinder 3.

[0018] The base end of the telescopic boom 14 is fixed to the slewing platform 12, and it can be raised and lowered and expanded and contracted. The actuator 2 expands and contracts the telescopic boom 14. The wire rope 16 is supported by the telescopic boom 14 and hangs down from the tip of the telescopic boom 14. The hook 17 is provided at the tip of the wire rope 16.

[0019] Next, with reference to FIGS. 1 and 2A to 2E, the telescopic boom 14 will be described. The telescopic boom 14 has a plurality of booms combined in a telescopic manner. Specifically, the plurality of booms are, in order from the inside, a tip boom 141, an intermediate boom 142, and a base boom 143.

[0020] The telescopic boom 14 transitions from the contracted state shown in FIG. 2A to the extended state shown in FIG. 1 by extending the booms arranged inside in order. Note that there may be a plurality of 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 a pair of cylinder pin receiving portions 1411, 1412 and a pair of boom pin receiving portions 141b at the base end portion. The pair of cylinder pin receiving portions 1411, 1412 and the pair of boom pin receiving portions 141b are through holes, respectively.

[0022] The pair of cylinder pin receivers 1411 and 1412 are provided coaxially with each other at the base end portion of the tip boom 141. The pair of cylinder pin receivers 1411 and 1412 are respectively detachable from a pair of cylinder connection pins 454A and 454B provided on the cylinder member 32 of the telescopic cylinder 3.

[0023] The cylinder connection pins 454A and 454B are respectively biased outward (in the direction from the base end portion to the tip end portion of the cylinder connection pins 454A and 454B) by a first biasing mechanism 455 described later. The cylinder connection pins 454A and 454B move inward (in the direction from the tip end portion to the base end portion of the cylinder connection pins 454A and 454B) based on the operation of a cylinder connection mechanism 45 described later.

[0024] In a state where the cylinder connection pins 454A and 454B are engaged with the pair of cylinder pin receivers 1411 and 1412, the tip boom 141 is movable in the telescopic direction together with the cylinder member 32.

[0025] The pair of boom pin receivers 141b are provided coaxially with each other around the cylinder pin receivers 1411 and 1412. The boom pin receivers 141b are respectively detachable from a pair of boom connection pins 144a. In the case shown in the figure, for convenience of explanation, the pair of boom pin receivers 141b and the pair of cylinder pin receivers 1411 and 1412 are shown in a state where they are displaced in the axial direction of the telescopic boom 14. Actually, the pair of boom pin receivers 141b and the pair of cylinder pin receivers 1411 and 1412 are provided in alignment in the axial direction of the telescopic boom 14 and at displaced positions in the circumferential direction of the telescopic boom 14.

[0026] The pair of boom connection pins 144a are respectively biased outward (in the direction from the base end portion to the tip end portion of the boom connection pins 144a) by a second biasing mechanism 463 described later. The pair of boom connection pins 144a respectively connect the tip boom 141 and the intermediate boom 142. The pair of boom connection pins 144a move inward (in the direction from the tip end portion to the base end portion of the boom connection pins 144a) based on the operation of a boom connection mechanism 46 described later.

[0027] In a state where the tip boom 141 and the intermediate boom 142 are connected by a pair of boom connection pins 144a, the boom connection pin 144a is inserted so as to be bridged 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] In the connected state of the tip boom 141 and the intermediate boom 142, the tip boom 141 is prohibited from moving relative to the intermediate boom 142. On the other hand, in the unconnected state of the tip boom 141 and the intermediate boom 142, 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, at its base end portion, 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, and has, at its tip portion, a pair of second boom pin receiving portions 142c. 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 through holes.

[0030] The pair of cylinder pin receiving portions 142a and the pair of first boom pin receiving portions 142b are substantially the same as the pair of cylinder pin receiving portions 1411, 1412 and the pair of boom pin receiving portions 141b of the tip boom 141, respectively. In the illustrated case, for the sake of convenience of explanation, the pair of first boom pin receiving portions 142b and the pair of cylinder pin receiving portions 142a are shown in a state shifted in the axial direction of the telescopic boom 14. Actually, 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 positions shifted in the circumferential direction of the telescopic boom 14.

[0031] A pair of third boom pin receivers 142d are provided coaxially with each other on the proximal end side of the pair of first boom pin receivers 142b. A pair of boom connection pins 144b are inserted into the pair of third boom pin receivers 142d respectively. The pair of boom connection pins 144b connect the intermediate boom 142 and the proximal boom 143.

[0032] A pair of second boom pin receivers 142c are provided coaxially with each other at the tip of the intermediate boom 142. A pair of boom connection pins 144a are inserted into the pair of second boom pin receivers 142c respectively.

[0033] The actuator 2 is an actuator for expanding and contracting the telescopic boom 14. As shown in FIGS. 2A to 4C, the actuator 2 has a telescopic cylinder 3 and a pin movement mechanism 4. The actuator 2 is disposed in the internal space of the tip boom 141 in the contracted state of the telescopic boom 14 (the state shown in FIG. 2A).

[0034] The telescopic cylinder 3 has a rod member 31 and a cylinder member 32. The telescopic cylinder 3 moves the boom connected to the cylinder member 32 via cylinder connection pins 454A and 454B described later.

[0035] The pin movement 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 connection mechanism 45, and a boom connection mechanism 46 supported by a trunnion (not shown).

[0036] Hereinafter, each member constituting the actuator 2 will be described based on the state in which each member is incorporated into the actuator 2.

[0037] Still, the trunnion (not shown) is fixed to the cylinder member 32 of the telescopic cylinder 3. Therefore, the pin movement mechanism 4 is supported by the cylinder member 32 of the telescopic cylinder 3. The pin movement mechanism 4 moves in the telescopic direction of the telescopic boom 14 (in other words, the axial direction of the telescopic boom 14) together with the cylinder member 32. The cylinder member 32 corresponds to an example of the movable part of the actuator.

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

[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). The electric motor 41 is connected to a speed reducer 431 as shown in FIGS. 3A to 4C. The electric motor 41 is connected to a power supply device (not shown) provided on the slewing platform 12 via a power supply cable.

[0040] The brake mechanism 42 applies a braking force to the electric motor 41. The brake mechanism 42 prevents rotation of the output shaft of the electric motor 41 when the electric motor 41 is in a stopped state. Thereby, the state of the pin movement mechanism 4 is maintained when the electric motor 41 is in a stopped state.

[0041] The brake mechanism 42 is connected to a power supply device (not shown) provided on the slewing platform 12 via a power supply cable. Incidentally, the position information detection device 44 described later is also connected to a power supply device (not shown) provided on the slewing platform 12 via a power supply cable.

[0042] Furthermore, the position information detection device 44 is connected to a control unit (not shown) provided on the swivel base 12 via a signal transmission cable. The power supply cables for the electric motor 41, the power supply cable for the brake mechanism 42, the power supply cable for the position information detection device 44, and the signal transmission cable of the position information detection device 44 are bundled together into a single multi-core cable and arranged in the internal space of the telescopic boom 14. With such a configuration, the internal space of the telescopic boom 14 can be efficiently utilized.

[0043] Specifically, the brake mechanism 42 operates in the contracted state of the cylinder connection mechanism 45 or the contracted state of the boom connection mechanism 46, which will be described later, to maintain the states of the cylinder connection mechanism 45 and the boom connection mechanism 46. Note that the state of the brake mechanism 42 is switched by a control unit (not shown). Also, the state of the brake 42 may be switched based on the operation of an operator.

[0044] The transmission mechanism 43 transmits the power of the electric motor 41 to the cylinder connection mechanism 45 and the boom connection mechanism 46. The transmission mechanism 43 includes a speed reducer 431 and a transmission shaft 432.

[0045] The speed reducer 431 reduces the rotation of the electric motor 41 and transmits it to the transmission shaft 432. The transmission shaft 432 transmits the rotation of the speed reducer 431 to a switching mechanism 5, which will be described later. Also, a position information detection device 44 for detecting information on the positions of the cylinder connection pins 454A, 454B and the pair of boom connection pins 144a, 144b is provided at the tip of the transmission shaft 432.

[0046] The information on the positions of the cylinder connection pins 454A, 454B and the pair of boom connection pins 144a, 144b is, for example, the amount of movement from the reference positions of the cylinder connection pins 454A, 454B or the pair of boom connection pins 144a, 144b. The positions of the cylinder connection pins 454A, 454B shown in Fig. 3A are the reference positions of the cylinder connection pins 454A, 454B. Also, the position of the pair of boom connection pins 144a shown in Fig. 4A is the reference position of the boom connection pin 144a.

[0047] The switching mechanism 5 is selectively connected to one of the connecting mechanisms of the cylinder connecting mechanism 45 and the boom connecting mechanism 46 described later, and transmits the power of the electric motor 41 to one of the connecting mechanisms.

[0048] With reference to FIGS. 3A to 3C, FIGS. 4A to 4C, and FIGS. 5A to 6B, the configuration of the switching mechanism 5 will be described. The switching mechanism 5 includes 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 corresponds to 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 through 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] Hereinafter, in the description of the switching mechanism 5, when the axial direction is mentioned without particular notice, it means the axial direction of the motor-side clutch gear 6. Note that the clutch actuator will be described in Embodiment 2 below. It is also possible to apply the clutch actuator in Embodiment 2 to the switching mechanism 5 of the present embodiment.

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

[0053] The first tooth portion 61 on the motor side has a plurality of first convex portions 611 on the motor side that are arranged side by side in a circumferentially spaced-apart state. The first convex portion 611 on the motor side is a convex portion that extends toward the boom-side clutch gear 7 described later. The first convex portion 611 on the motor side has a first inclined surface 6111 on the end surface on the boom-side clutch gear 7 side.

[0054] The second tooth portion 62 on the motor side has a plurality of second convex portions 622 on the motor side that are arranged side by side in a circumferentially spaced-apart state. The second convex portion 622 on the motor side is a convex portion that extends toward the cylinder-side clutch gear 8 described later. The second convex portion 622 on the motor side has a second inclined surface 6221 on the end surface on the cylinder-side clutch gear 8 side.

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

[0056] The boom-side clutch gear 7 corresponds to an example of the first transmission member and is connected to the boom connection mechanism 46 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). 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 schematically shown. The boom-side pinion gear 73 may be 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 transmitted from the motor-side clutch gear 6 to the boom connection mechanism 46. Also, in FIGS. 3A to 4C, the connection structure between the transmission shaft 432 and the motor-side clutch gear 6 is also schematically shown.

[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 engageable with the motor-side clutch gear 6. The gear body 71 has a boom-side tooth portion 711 at one end in the axial direction (also referred to as the first end). The boom-side tooth portion 711 corresponds to an example of the first tooth portion.

[0059] The boom-side tooth portion 711 has a plurality of boom-side convex portions 712 provided side by side in a circumferentially spaced state. The boom-side convex portion 712 is a convex portion extending toward the motor-side clutch gear 6. The boom-side convex portion 712 has a boom-side inclined surface 7121 on the end surface 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 a function of guiding the axial movement of the motor-side clutch gear 6.

[0062] Also, the shaft portion 72 also has a 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 connection mechanism 46 (specifically, the second rack bar 461a).

[0065] The cylinder-side clutch gear 8 corresponds to an example of the second transmission member and is connected to a cylinder connection mechanism 45 described later. Specifically, the cylinder-side clutch gear 8 is connected to the cylinder connection mechanism 45 via a cylinder-side pinion gear 83 (see FIGS. 3A to 4C). In FIGS. 3A to 4C, the connection structure of the cylinder-side clutch gear 8, the cylinder-side pinion gear 83, and the cylinder connection mechanism 45 is schematically shown. The cylinder-side pinion gear 83 may be various pinion gears (for example, bevel gears, spur gears, or helical gears). The cylinder-side clutch gear 8 transmits the power of the electric motor 41 transmitted from the motor-side clutch gear 6 to the cylinder connection 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 engageable with the motor-side clutch gear 6. The gear body 81 has a cylinder-side tooth portion 811 at one end (also referred to as the first end) in the axial direction. The cylinder-side tooth portion 811 corresponds to an example of the second tooth portion.

[0068] The cylinder-side tooth portion 811 has a plurality of cylinder-side convex portions 812 arranged side by side in a circumferentially spaced state. The cylinder-side convex portion 812 is a convex portion extending toward the motor-side clutch gear 6. The cylinder-side convex portion 812 has 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 from the gear body 81 toward the motor-side clutch gear 6 in the axial direction.

[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 a function of guiding the axial movement of the motor-side clutch gear 6.

[0071] Also, the shaft portion 82 also has a 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 connection 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 connection mechanism 45 (specifically, the first rack bar 451). The operation of the switching mechanism 5 having the above configuration will be described later.

[0074] The cylinder connection mechanism 45 corresponds to an example of the first connection mechanism, connects the boom and the telescopic cylinder 3, and releases the connection by a motor. Specifically, the cylinder connection mechanism 45 operates based on the power of the electric motor 41 and transitions between an extended state (see FIG. 3A) and a contracted state (see FIG. 3C).

[0075] FIGS. 3A to 3C are schematic diagrams of the pin movement mechanism 4 in a state of viewing the pin movement mechanism 4 from the proximal end side (rear side) of the telescopic boom 14. The operation of the cylinder connection mechanism 45 transitioning from the extended state to the contracted state is the pulling-out operation of the cylinder connection mechanism 45. The operation of the cylinder connection mechanism 45 transitioning from the contracted state to the extended state is the insertion operation of the cylinder connection mechanism 45.

[0076] In the extended state of the cylinder connection mechanism 45, the cylinder connection pins 454A and 454B and the cylinder pin receiving portions 1411 and 1412 of the boom (for example, the tip boom 141) are in an engaged state. In this engaged state, the boom and the cylinder member 32 (see FIGS. 2A to 2E) are connected.

[0077] Also, in the contracted state of the cylinder connection mechanism 45, the cylinder connection pins 454A and 454B and the cylinder pin receiving portions 1411 and 1412 are in a disengaged state. In this disengaged state, the engagement between the boom and the cylinder member 32 is released.

[0078] Specifically, the cylinder connection mechanism 45 includes a first rack bar 451, a first gear mechanism 452, a second gear mechanism 453, cylinder connection pins 454A and 454B, and a first biasing mechanism 455.

[0079] The first rack bar 451 moves in its axial direction in response to the 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 in the extended state of the cylinder connection mechanism 45 (see FIG. 3A).

[0080] On the other hand, the first rack bar 451 is located at the second position in the contracted state of the cylinder connection mechanism 45 (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 extended state, when the cylinder side clutch gear 8 rotates by a predetermined amount, the first rack bar 451 moves in response to the rotation of the cylinder side clutch gear 8.

[0082] Also, the first rack bar 451 has a second rack tooth portion and a third rack tooth portion. The second rack tooth portion meshes with the first gear mechanism 452 described later. The third rack tooth portion meshes with the second gear mechanism 453 described later.

[0083] The first gear mechanism 452 rotates in response to the movement of the first rack bar 451. Further, the first gear mechanism 452 meshes with a cylinder connection pin 454A described later.

[0084] The second gear mechanism 453 rotates in response to the movement of the first rack bar 451. Further, the second gear mechanism 453 meshes with a cylinder connection pin 454B described later.

[0085] The cylinder connection pins 454A and 454B are provided on the same straight line. Such cylinder connection pins 454A and 454B are supported by a trunnion (not shown). The cylinder connection pins 454A and 454B move in the axial direction of the cylinder connection pins 454A and 454B in response to the rotation of the first gear mechanism 452 and the second gear mechanism 453.

[0086] The first biasing mechanism 455 returns the cylinder connection mechanism 45 to the extended state when the electric motor 41 is de-energized in the contracted state of the cylinder connection mechanism 45 (see FIG. 3C).

[0087] In other words, the first biasing mechanism 455 returns the cylinder connection pins 454A and 454B to the reference position (in other words, the inserted state) when the electric motor 41 is de-energized (stopped state) and the brake mechanism 42 is in the OFF state in the contracted state of the cylinder connection mechanism 45.

[0088] Specifically, the first biasing mechanism 455 has a pair of coil springs 455a and 455b (see FIG. 3A). The coil spring 455a is provided between a trunnion (not shown) and the cylinder connection pin 454A.

[0089] The coil spring 455a constantly biases the cylinder connection pin 454A. The direction in which the coil spring 455a biases the cylinder connection pin 454A coincides with the direction from the base end portion to the tip end portion of the cylinder connection pin 454A.

[0090] The coil spring 455b is provided between a 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 portion to the tip end portion 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. Note that the arrangements of the coil springs 455a and 455b are not limited to the arrangements in this embodiment. The operation of the cylinder connecting mechanism 45 will be described later.

[0092] The boom connecting mechanism 46 corresponds to an example of the second connecting mechanism, connects adjacent booms, and releases the connection by a motor. Specifically, based on the rotation of the electric motor 41, it transitions between an extended state (see FIG. 4A) and a contracted state (see FIG. 4C).

[0093] The operation in which the boom connecting mechanism 46 transitions from the extended state to the contracted state is the removal operation of the boom connecting mechanism 46. The operation in which the boom connecting mechanism 46 transitions from the contracted state to the extended state is the insertion operation of the boom connecting mechanism 46.

[0094] In the extended state, the boom connecting mechanism 46 can take either an engaged state or a disengaged state with respect to a boom connecting pin (for example, a pair of boom connecting pins 144a). When the boom connecting mechanism 46 is in an engaged state with the boom connecting pin and transitions from the extended state to the contracted state, the boom connecting pin is disengaged from the boom.

[0095] Also, when the boom connecting mechanism 46 is in an engaged state with the boom connecting pin and transitions from the contracted state to the extended state, the boom connecting pin is engaged with the boom.

[0096] As shown in FIGS. 4A to 4C, the boom connecting mechanism 46 includes a pair of second rack bars 461a and 461b, a synchronizing gear 462, and a second biasing mechanism 463.

[0097] The pair of second rack bars 461a and 461b are each, for example, shaft members that are long in the left - right direction and are arranged in parallel while being spaced apart in the front - rear direction. The pair of second rack bars 461a and 461b are each arranged above the first rack bar 451 of the cylinder connection mechanism 45.

[0098] The pair of second rack bars 461a and 461b each have synchronization rack teeth on the opposing surfaces. The synchronization rack teeth are each meshed with a synchronization gear 462. When the synchronization gear 462 rotates, one of the second rack bars 461a and the other second rack bar 461b move in opposite directions in the axial direction of the second rack bars 461a and 461b.

[0099] The pair of second rack bars 461a and 461b each have locking claw portions 461g and 461h at their tip ends. The locking claw portions 461g and 461h engage with the boom connection pins (for example, boom connection pins 144a and 144b) when moving the boom connection pins.

[0100] One of the second rack bars 461a moves in its own axial direction in response to the power (specifically, rotation) transmitted from the switching mechanism 5 (specifically, the boom - side clutch gear 7) via the boom - side pinion gear 73. One of the second rack bars 461a is located at the first position in the extended state of the boom connection mechanism 46. Also, one of the second rack bars 461a is located at the second position in the contracted state of the boom connection mechanism 46. That is, one of the second rack bars 461a moves between the first position and the second position.

[0101] When the boom - side clutch gear 7 of the switching mechanism 5 rotates by a predetermined amount from the extended state of the boom connection mechanism 46, one of the second rack bars 461a moves in its own axial direction in response to the rotation of the boom - side clutch gear 7.

[0102] Further, when one of the second rack bars 461a moves, the synchronizing gear 462 rotates, causing the other second rack bar 461b to move in its axial direction. The moving direction of one second rack bar 461a is opposite to that of the other second rack bar 461b.

[0103] The second biasing mechanism 463 returns the boom connecting mechanism 46 to the extended state when the electric motor 41 is de-energized and the braking mechanism 42 is in the OFF state in the contracted state of the boom connecting mechanism 46. The second biasing mechanism 463 biases the pair of second rack bars 461a and 461b in a direction away from each other.

[0104] Specifically, the second biasing mechanism 463 is composed of a pair of coil springs 463a and 463b. The pair of coil springs 463a and 463b bias the base end portions of the pair of second rack bars 461a and 461b toward the tip side, respectively.

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

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

[0107] The boom connecting mechanism 46 transitions from the extended state to the contracted state based on the power of the electric motor 41. Such an operation is referred to as the contraction operation of the boom connecting mechanism 46. Further, such an operation is also referred to as the pulling-out operation of the boom connecting mechanism 46.

[0108] In the pulling-out operation of the boom connecting mechanism 46, the boom connecting mechanism 46 pulls out the pair of boom connecting pins 144a from, for example, the pair of first boom pin receiving portions 142b of the intermediate boom 142. Thereby, the connection between the tip boom 141 and the intermediate boom 142 is released. Hereinafter, the operation of the boom connecting mechanism 46 in the case of targeting the pair of boom connecting pins 144a will be described.

[0109] When the boom connection mechanism 46 is in the state before performing the removal operation of the boom connection mechanism 46, 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, the non-connection state, or the initial state of the switching mechanism 5. Further, 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 FIG. 5A, the states of the respective members of the pin movement mechanism 4 are as follows. Boom connection mechanism 46: Extended state Cylinder connection mechanism 45: Extended state Boom connection pin 144a: Inserted state Cylinder connection pins 454A, 454B: Inserted state Electric motor 41: OFF Brake mechanism 42: OFF Switching mechanism 5: Neutral state

[0111] When the boom connection mechanism 46 performs the removal operation of 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 the first direction (the direction of arrow A1 in FIG. 5A). The first direction is one side in the axial direction of the motor-side clutch gear 6.

[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] Then, the switching mechanism 5 becomes the state shown in FIG. 5B. The state shown in FIG. 5B is referred to as the first connection state of the switching mechanism 5. In the first connection state of the switching mechanism 5, the motor-side clutch gear 6 engages with the boom-side clutch gear 7. Further, 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 first motor-side 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 is in the first connection 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 connection 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 boom-side clutch gear 7. In the first connection state of the switching mechanism 5, the first motor-side convex portion 611 of the first motor-side tooth portion 61 in the motor-side clutch gear 6 and the boom-side convex portion 712 of the boom-side tooth portion 711 in the boom-side clutch gear 7 engage with each other in the circumferential direction.

[0116] Also, in the first connection 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) in a state of facing each other in the axial direction.

[0117] When the switching mechanism 5 is in the state shown in FIG. 5B, the states of the respective members of the pin movement mechanism 4 are as follows. Boom connection mechanism 46: Extended state Cylinder connection mechanism 45: Extended state Boom connection pin 144a: Inserted state Cylinder connection pins 454A, 454B: Inserted state Electric motor 41: OFF Brake mechanism 42: OFF Switching mechanism 5: First connection state

[0118] Next, in the state shown in FIG. 5B, the control unit (not shown) turns on the electric motor 41. Then, the control unit drives the electric motor 41 in the 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] Then, the motor-side clutch gear 6 rotates in the direction of arrow A3 in Fig. 5B. The rotation direction of the motor-side clutch gear 6 at this time is referred to as the 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] When the motor-side clutch gear 6 rotates as described above, the boom-side clutch gear 7 engaged with the motor-side clutch gear 6 also rotates. Then, the rotation of the boom-side clutch gear 7 is 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 contracted 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 through 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 connection pins 144a through the above transmission path, the pair of boom connection pins 144a move in the direction of separating from the pair of first boom pin receiving portions 142b.

[0125] Still, when the electric motor 41 is driven in the second rotation direction in the state shown in FIG. 5B, 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 the case of this embodiment, in the state shown in FIG. 5B, when the motor-side clutch gear 6 rotates in the second rotation direction, 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 be able to transmit power only when the motor-side clutch gear 6 rotates in a predetermined direction (in the case of this embodiment, the first rotation direction). Such a configuration can prevent the boom connection mechanism 46 from operating unintentionally due to a malfunction of the electric motor 41.

[0126] The position information detection device 44 detects that the pair of boom connection pins 144a have detached 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] Still, the states of the respective members of the pin movement mechanism 4 in the contracted state of the boom connection mechanism 46 shown in FIG. 4C are as follows. Boom connection mechanism 46: Contracted state Cylinder connection mechanism 45: Extended state Boom connection pin 144a: Removed state Cylinder connection pins 454A, 454B: Inserted state Electric motor 41: OFF Brake mechanism 42: ON Switching mechanism 5: First connection state

[0128] Next, the transition of the boom connection 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 in the non-energized state of the electric motor 41.

[0129] Specifically, when the brake mechanism 42 is in the OFF state in the contracted state of the boom connection mechanism 46, 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. Also, the motor-side clutch gear 6 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 by a predetermined amount, the rotation of the boom-side clutch gear 7 and the motor-side clutch gear 6 stops. As a result, the boom connection mechanism 46 transitions from the contracted state to the extended state.

[0131] In addition, when the boom connection mechanism 46 transitions from the contracted state to the extended state and the rotation of the boom-side clutch gear 7 in the second rotation direction stops, the motor-side clutch gear 6 may rotate in the second rotation direction due to inertia.

[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 FIG. 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), and the motor-side clutch gear 6 moves in the second direction.

[0134] The amount of movement of the motor-side clutch gear 6 in the second direction at this time 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 connection 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 larger 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. For this reason, rotation is not transmitted from the cylinder-side clutch gear 8 to the cylinder connection mechanism 45. As a result, it is possible to reliably prevent the cylinder connection mechanism 45 from operating unintentionally.

[0136] Next, in the state shown in FIG. 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. Then, the switching mechanism 5 assumes the state shown in FIG. 5A. The state shown in FIG. 5A is the neutral state of the switching mechanism 5.

[0137] With reference to FIGS. 3A to 3C, FIG. 6A, and FIG. 6B, an example of the operation of the switching mechanism 5 and the cylinder connection mechanism 45 will be described.

[0138] The cylinder connection mechanism 45 transitions from the extended state (see FIG. 3A) to the contracted state (see FIG. 3C) based on the power of the electric motor 41. Such an operation is referred to as the contraction operation of the cylinder connection mechanism 45. Also, such an operation is also referred to as the extraction operation of the cylinder connection mechanism 45. In the extraction operation of the cylinder connection mechanism 45, the cylinder connection pins 454A and 454B are pulled out from the cylinder pin receiving portions 1411 and 1412.

[0139] The cylinder connection mechanism 45 transitions from the contracted state to the extended state based on the biasing force of the first biasing mechanism 455. Such an operation is referred to as the expansion operation of the cylinder connection mechanism 45. Also, such an operation is also referred to as the insertion operation of the cylinder connection mechanism 45. In the insertion operation of the cylinder connection mechanism 45, the cylinder connection pins 454A and 454B are inserted into the cylinder pin receiving portions 1411 and 1412.

[0140] When the cylinder connection mechanism 45 is in the state before performing the removal operation of the cylinder connection mechanism 45, 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, the unconnected state, or the 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 FIG. 6A, the states of the respective members of the pin movement mechanism 4 are as follows. Boom connection mechanism 46: Extended state Cylinder connection mechanism 45: Extended state Boom connection pin 144a: Inserted state Cylinder connection pins 454A, 454B: Inserted state Electric motor 41: OFF Brake mechanism 42: OFF Switching mechanism 5: Neutral state

[0142] In the neutral state of the switching mechanism 5, the motor-side clutch gear 6 is located at the neutral position. In the neutral state of the switching mechanism 5, 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 connection mechanism 45 performs the removal operation of the cylinder connection mechanism 45, 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] Then, the switching mechanism 5 assumes the state shown in FIG. 6B. The state shown in FIG. 6B is referred to as the second connection state of the switching mechanism 5. In the second connection state of the switching mechanism 5, the motor-side clutch gear 6 engages with the cylinder-side clutch gear 8. Also, 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 second motor-side tooth portion 62 of the motor-side clutch gear 6 engages with the cylinder-side tooth portion 811 of the cylinder-side clutch gear 8. When the switching mechanism 5 is in the second connection 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 connection 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 connection state of the switching mechanism 5, the second motor-side convex portion 622 of the second motor-side 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 engage with each other in the circumferential direction.

[0148] Also, in the second connection 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) in a state of facing each other in the axial direction.

[0149] When the switching mechanism 5 is in the state shown in FIG. 6B, the states of the respective members of the pin movement mechanism 4 are as follows. Boom connection mechanism 46: Extended state Cylinder connection mechanism 45: Extended state Boom connection pin 144a: Inserted state Cylinder connection pins 454A, 454B: Inserted state Electric motor 41: OFF Brake mechanism 42: OFF Switching mechanism 5: Second connection 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 the 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 arrow A3 in FIG. 6B (in other words, the first rotation direction).

[0151] In the case of this embodiment, the rotation direction of the electric motor 41 in the state where 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 in the state where 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 in the removal operation of the boom connection mechanism 46 (that is, the first rotation direction) is the same as the rotation direction of the motor-side clutch gear 6 in the removal operation of the cylinder connection mechanism 45 (that is, the first rotation direction). Such a configuration contributes to suppressing the brush wear of the electric motor 41 when the electric motor 41 is a brushed DC motor. Also, in the case of such a configuration, a switching circuit for switching the rotation direction of the electric motor 41 is unnecessary. As a result, the manufacturing cost 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 in the motor-side clutch gear 6 pushing the cylinder-side convex portion 812 of the cylinder-side tooth portion 811 in the cylinder-side clutch gear 8 in the circumferential direction (that is, the first rotation direction).

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

[0155] As a result, the cylinder connection mechanism 45 transitions from the extended 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 connection pins 454A and 454B through the following first transmission path and second transmission path.

[0156] The first transmission path is the path through which the power of the cylinder-side clutch gear 8 is transmitted to the cylinder connection 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 connection pin 454A

[0157] The second transmission path is the path through which the power of the cylinder-side clutch gear 8 is transmitted to the cylinder connection 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 connection pin 454B

[0158] When the power of the cylinder-side clutch gear 8 is transmitted to the cylinder connection pin 454A through the above first transmission path, the cylinder connection pin 454A moves in the direction of separating from the cylinder pin receiving portion 1411 (the left side in Fig. 3A).

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

[0160] Still, when the electric motor 41 is driven in the second rotation direction in the state shown in FIG. 6B, 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 the case of 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 be able to transmit power only when the motor-side clutch gear 6 rotates in a predetermined direction (in the case of this embodiment, the first rotation direction). Such a configuration can prevent the cylinder connection mechanism 45 from operating unintentionally due to a malfunction of the electric motor 41.

[0161] The position information detection device 44 detects that the pair of cylinder connection pins 454A and 454B have detached from the pair of cylinder pin receiving portions 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, a control unit (not shown) stops the operation of the electric motor 41.

[0162] Still, the states of the respective members of the pin movement mechanism 4 in the contracted state of the cylinder connection mechanism 45 are as follows. Boom connection mechanism 46: Extended state Cylinder connection mechanism 45: Contracted state Boom connection pin 144a: Inserted state Cylinder connection pins 454A, 454B: Removed state Electric motor 41: OFF Brake mechanism 42: ON Switching mechanism 5: Second connection state

[0163] Next, the transition of the cylinder connection mechanism 45 from the contracted state to the extended 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 in the non-energized state of the electric motor 41.

[0164] Specifically, when the brake mechanism 42 is in the OFF state in the contracted state of the cylinder connection mechanism 45, 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. Also, together with the cylinder-side clutch gear 8, the motor-side clutch gear 6 rotates. The rotation direction at this time is the second rotation direction.

[0165] When the cylinder-side clutch gear 8 rotates by 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 connection mechanism 45 transitions from the contracted state to the extended state.

[0166] In addition, when the cylinder connection mechanism 45 transitions from the contracted state to the extended 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 alone in the second rotation direction due to inertia. And when the motor-side clutch gear 6 rotates alone in the second rotation direction with the cylinder-side clutch gear 8 stopped, the motor-side clutch gear 6 may move in the direction of arrow A1 in FIG. 6B (that is, 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 (in other words, pushed in) the cylinder-side inclined surface 8121 of the cylinder-side clutch gear 8, and the motor-side clutch gear 6 moves in the first direction.

[0168] The amount of movement of the motor-side clutch gear 6 in the first direction at this time is at most the height of the motor-side second convex portion 622 and the cylinder-side convex portion 812. In the case of this embodiment, in the second connection 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 larger 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. For this reason, rotation is not transmitted from the cylinder-side clutch gear 8 to the boom-side clutch gear 7. As a result, it is possible to reliably prevent the boom connection mechanism 46 from operating unintentionally.

[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 assumes the neutral state shown in FIG. 6A.

[0171] In the case of the mobile crane 1 of the present embodiment having the above-described configuration, since the cylinder connection mechanism 45 and the boom connection mechanism 46 are electric, it is not necessary to provide a hydraulic circuit such as a conventional structure in the internal space of the telescopic boom 14. Therefore, the space used by the hydraulic circuit can be effectively utilized, and the degree of freedom in design in the internal space of the telescopic boom 14 can be improved.

[0172] Also, in the case of the mobile crane 1 of the present embodiment, the power of one electric motor 41 is selectively distributed to the cylinder connection mechanism 45 and the boom connection mechanism 46 by the switching mechanism 5. Such a configuration contributes to miniaturization of the pin movement mechanism 4. In addition, the operation and effects of the mobile crane 1 according to the present embodiment are as described above.

[0173] [Embodiment 2] Next, with reference to FIGS. 7A to 7C, the mobile crane 1B according to Embodiment 2 of the present invention will be described. Also, for the configurations of the cylinder connection mechanism 45 and the boom connection mechanism 46, refer to FIGS. 3A to 3C and FIGS. 4A to 4C.

[0174] Figs. 7A to 7C are diagrams showing the configuration of the switching mechanism 5B of the pin movement mechanism 4B incorporated in the mobile crane 1B. The state of the switching mechanism 5B shown in Fig. 7A corresponds to the state of the switching mechanism 5 shown in Figs. 5A and 6A described above. The state of the switching mechanism 5B shown in Fig. 7B corresponds to the state of the switching mechanism 5 shown in Fig. 5B described above. The state of the switching mechanism 5B shown in Fig. 7C corresponds to the state of the switching mechanism 5 shown in Fig. 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. Hereinafter, among the configurations of the mobile crane 1B according to the present embodiment, the configurations different from those of the mobile crane 1 according to the above-described Embodiment 1 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 the same as that of the motor-side first tooth portion 61 in the above-described Embodiment 1. Therefore, the description of the configuration of the motor-side first tooth portion 61B may be appropriately cited from the description of the configuration of the motor-side first tooth portion 61 in the above-described Embodiment 1.

[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 the same as that of the motor-side second tooth portion 62 in the above-described Embodiment 1. Therefore, the description of the configuration of the motor-side second tooth portion 62 may be appropriately cited from the description of the configuration of the motor-side second tooth portion 62 in the above-described Embodiment 1.

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

[0180] The boom-side clutch gear 7B is connected to the boom connection mechanism 46 (see FIGS. 4A to 4C). The boom-side clutch gear 7B transmits the power of the electric motor 41 transmitted from the motor-side clutch gear 6B to the boom connection 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 above-described Embodiment 1. Therefore, the description of the configuration of the gear body 71B may be appropriately incorporated by reference to the description of the configuration of the gear body 71 in the above-described Embodiment 1. Further, 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 configuration of the boom-side pinion gear 73 in the above-described Embodiment 1. Therefore, the description of the configuration of the boom-side pinion gear 73B may be appropriately incorporated by reference to the description of the configuration of the boom-side pinion gear 73 in the above-described Embodiment 1.

[0182] The cylinder-side clutch gear 8B is connected to the cylinder connection mechanism 45 (see FIGS. 3A to 3C). The cylinder-side clutch gear 8B transmits the power of the electric motor 41 transmitted from the motor-side clutch gear 6B to the cylinder connection 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 that of the gear body 81 of the cylinder-side clutch gear 8 in the above-described Embodiment 1. Therefore, the description of the configuration of the gear body 81B may be appropriately incorporated by reference to the description of the configuration of the gear body 81 in the above-described Embodiment 1. Further, 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 that of the cylinder-side pinion gear 83 in the above-described Embodiment 1. Therefore, the description of the configuration of the cylinder-side pinion gear 83B may be appropriately incorporated by reference to the description of the configuration of the cylinder-side pinion gear 83 in the above-described Embodiment 1.

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

[0185] The first drive unit 91a is an actuator that generates power in the axial direction. The first drive unit 91a is, for example, a solenoid-type actuator that can expand and contract in the axial direction.

[0186] The first spring 92a corresponds to 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 in a state where the power of the electric motor 41 can be transmitted to the boom connection mechanism 46 (see FIG. 4A).

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

[0188] When the first driving part 91a extends in the first direction (the direction indicated by the arrow A1 in FIG. 7A), the first spring 92a is pushed in the first direction by the first driving part 91a. Then, the first spring 92a pushes the first pressing part 93a in the first direction.

[0189] The first pressing part 93a is a member for pushing the first gear element 6a of the motor-side clutch gear 6B in the first direction. The first pressing part 93a is supported by the fixing part 99 in a state of being movable in the axial direction. The first pressing part 93a is plate-shaped.

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

[0191] The second driving part 91b is an actuator that generates power in the axial direction. The second driving part 91b is, for example, a solenoid-type actuator that can expand and contract in the axial direction. The second spring 92b is provided between the second driving part 91b and the second pressing part 93b.

[0192] The second spring 92b corresponds to an example of an elastic member and transmits the power of the second driving part 91b to the motor-side clutch gear 6B. The second spring 92b biases the motor-side clutch gear 6B toward the cylinder connection mechanism 45 in a state where the power of the electric motor 41 can be transmitted to the cylinder connection mechanism 45 (see FIG. 3A).

[0193] One end part of the second spring 92b (also referred to as the first end part) is connected to the tip part of the second driving part 91b. The other end part of the second spring 92b (also referred to as the second end part) is connected to the second pressing part 93b.

[0194] When the second driving part 91b extends in the second direction (the direction indicated by the arrow A2 in FIG. 7A), the second spring 92b is pushed in the second direction by the second driving part 91b. Then, the second spring 92b, which corresponds to an example of an elastic member, pushes the second pressing part 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 fixing portion 99 in a state of being movable in the axial direction. The second pressing portion 93b is plate-shaped.

[0196] The second pressing portion 93b has a through hole 930b that axially penetrates the second pressing portion 93b. The connecting shaft portion 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 motor-side clutch gear 6B is moved by the clutch actuator 9, the operation of the switching mechanism 5 in the above-described Embodiment 1 is the same.

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

[0199] When performing the removal operation of the boom connection mechanism 46, 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 portion 91a of the clutch actuator 9. Then, as shown in FIG. 7B, the first drive portion 91a extends in the first direction. When the first drive portion 91a extends, the first drive portion 91a presses the first spring 92a in the first direction. When the first spring 92a is pressed in the first direction by the first drive portion 91a, the first spring 92a presses the first pressing portion 93a in the first direction.

[0201] Then, the first pressing portion 93a moves in the first direction from the position of the first pressing portion 93a in FIG. 7A. When the first pressing portion 93a moves a predetermined amount in the first direction, the first pressing portion 93a abuts on the first gear element 6a of the motor-side clutch gear 6B. From this state, when the first driving portion 91a further extends in the first direction, the first pressing portion 93a pushes the first gear element 6a in the first direction.

[0202] As a result, as shown in FIG. 7B, the first gear element 6a engages with the boom-side clutch gear 7B. In a state where the first gear element 6a engages 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. Note that the state where the first gear element 6a engages with the boom-side clutch gear 7B is the first engagement state of the switching mechanism 5B.

[0203] In this state, the control unit (not shown) turns on the electric motor 41 (see FIG. 4A). Then, the control unit drives the electric motor 41 in the 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 (see FIG. 4A). Then, 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 link 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 contracted state shown in FIG. 4C. As a result, the removal operation of the boom connection mechanism 46 is performed, and the pair of boom connection pins 144a are detached from the pair of first boom pin receivers 142b of the intermediate boom 142.

[0207] Also, the insertion operation of the boom connection mechanism 46 is automatically performed 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 FIG. 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 by 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 explanation of the above Embodiment 1, in the insertion operation of the boom connection mechanism 46, when the boom-side clutch gear 7B stops, the motor-side clutch gear 6B may rotate in the second rotation direction due to inertial force.

[0209] When the boom-side clutch gear 7B stops and the motor-side clutch gear 6B rotates in the second rotation direction, the motor-side clutch gear 6B may move in the direction of arrow A2 in FIG. 7B (that is, the second direction). The reason for this is as described in Embodiment 1.

[0210] However, in the case of the present embodiment, in the first engagement state of the switching mechanism 5B, the first pressing portion 93a constantly biases the motor-side clutch gear 6B in the direction of arrow A1 in FIG. 7B (that is, the first direction) based on the biasing 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 (that is, the position of the motor-side clutch gear 6B in FIG. 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. Therefore, rotation is not transmitted from the cylinder-side clutch gear 8B to the cylinder connection mechanism 45. Thus, it is surely prevented that the cylinder connection mechanism 45 operates unintentionally.

[0213] Also, in the state shown in FIG. 7B, when the electric motor 41 is driven in the second rotation direction due to a malfunction, 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, the boom connection mechanism 46 does not malfunction. Thus, in the case of this 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 the correct correspondence.

[0215] In other words, when 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 is not transmitted to the boom connection mechanism 46.

[0216] Next, with reference to FIGS. 7A and 7C, the removal operation of the cylinder connection mechanism 45 will be described. When the cylinder connection mechanism 45 performs the removal operation of the cylinder connection 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, a 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. Then, as shown in FIG. 7C, the second drive unit 91b extends in the second direction. 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] Then, the second pressing unit 93b moves in the second direction from the position of the second pressing unit 93b in FIG. 7A. When the second pressing unit 93b moves a predetermined amount in the second direction, the second pressing unit 93b abuts on the second gear element 6b of the motor-side clutch gear 6B. From this state, when the second drive unit 91b further extends in the second direction, the second pressing unit 93b pushes the second gear element 6b in the second direction.

[0220] As a result, as shown in FIG. 7C, the second gear element 6b engages with the cylinder-side clutch gear 8B. In a state where the second gear element 6b engages 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. Note that the state where the second gear element 6b engages with the cylinder-side clutch gear 8B is the second engagement 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] Then, the motor-side clutch gear 6B rotates in the direction of arrow A4 in FIG. 7C. The rotation direction of the motor-side clutch gear 6B at this time is the second rotation direction. The second rotation direction is the opposite direction to the first rotation direction.

[0223] Thus, in the case of this embodiment, the rotation direction of the electric motor 41 in the state where 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 in the state where 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). Therefore, the cylinder-side clutch gear 8B rotates in the second rotation direction.

[0225] Incidentally, in the removal operation of the cylinder connection mechanism 45, the electric motor 41 may rotate in the first rotation direction. That is, the rotation direction of the electric motor 41 in the removal operation of the cylinder connection mechanism 45 may be the same as the rotation direction of the electric motor 41 in the removal operation of the boom connection 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 connection mechanism 45 via the cylinder-side clutch gear 8B.

[0227] Then, the cylinder connection mechanism 45 transitions from the extended state shown in FIG. 3A to the contracted state shown in FIG. 3C. As a result, the removal operation of the cylinder connection mechanism 45 is performed, and the pair of cylinder connection pins 454A, 454B are detached from the pair of cylinder pin receiving portions 1411, 1412 of the tip boom 141.

[0228] Further, when the brake mechanism 42 is in the OFF state in the contracted state of the cylinder connection mechanism 45, the cylinder connection mechanism 45 transitions from the contracted state to the expanded state. That is, the retracting operation of the cylinder connection mechanism 45 is performed. The retracting operation of the cylinder connection mechanism 45 is automatically performed 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 FIG. 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 by 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 explanation of the above-described Embodiment 1, in the retracting operation of the cylinder connection mechanism 45, when the cylinder-side clutch gear 8B stops, the motor-side clutch gear 6B may rotate in the first rotation direction due to inertia. When the motor-side clutch gear 6B rotates in the first rotation direction with the cylinder-side clutch gear 8B stopped, the motor-side clutch gear 6B may move in the direction of arrow A1 in FIG. 7C (that is, the first direction). The reason for this is as described in Embodiment 1.

[0231] However, in the case of the present embodiment, in the second engaged state of the switching mechanism 5B, the second pressing portion 93b constantly biases the motor-side clutch gear 6B in the direction of arrow A2 in FIG. 7C (that is, the second direction) based on the biasing 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 (that is, the first direction), the motor-side clutch gear 6B returns to its original position (that is, the position of the motor-side clutch gear 6B in FIG. 7C) based on the biasing 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 connecting mechanism 46. Thus, it is surely prevented that the boom connecting mechanism 46 operates unintentionally.

[0233] Also, when the electric motor 41 is driven in the first rotation direction due to a malfunction in the state shown in FIG. 7C, 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. Therefore, the cylinder connecting mechanism 45 does not malfunction either. Thus, in the case of this embodiment, the power (i.e., rotation) of the electric motor 41 is transmitted to the cylinder connecting mechanism 45 only when the clutch actuator 9 (specifically, the second drive unit 91b) and the electric motor 41 operate in the correct correspondence.

[0235] In other words, when the clutch actuator 9 (specifically, the second drive unit 91b) and the electric motor 41 operate in an incorrect correspondence, the power (i.e., rotation) of the electric motor 41 is not transmitted to the cylinder connecting mechanism 45. The configurations of the other parts of the mobile crane 1B, as well as the operations and effects, are the same as those of the mobile crane 1 according to the above-described Embodiment 1. 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 above-described Embodiment 1.

[0236] [Embodiment 3] Next, with reference to FIGS. 8A and 8B, a mobile crane 1C according to Embodiment 3 of the present invention will be described. Also, for the configurations of the cylinder connecting mechanism 45 and the boom connecting mechanism 46, refer to FIGS. 3A to 3C and FIGS. 4A to 4C.

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

[0238] In the mobile crane 1C of the present 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. Hereinafter, the configuration of the switching mechanism 5C will be described.

[0239] Note that the operations of the cylinder connection mechanism 45 and the boom connection mechanism 46 are the same as those of the cylinder connection mechanism 45 and the boom connection mechanism 46 of the mobile crane 1 according to the above-described Embodiment 1. Therefore, the descriptions overlapping with those of the above-described Embodiment 1 regarding the configurations and operations of the cylinder connection mechanism 45 and the boom connection mechanism 46 will be omitted.

[0240] The switching mechanism 5C selectively engages with one of the connection mechanisms of the cylinder connection mechanism 45 and the boom connection mechanism 46, and transmits the power of the electric motor 41 to one of the connection mechanisms. The switching mechanism 5C includes 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, the boom-side clutch gear 7C, and the cylinder-side clutch gear 8C are substantially the same as the configurations of the motor-side clutch gear 6, the boom-side clutch gear 7, and the cylinder-side clutch gear 8 in the above-described Embodiment 1.

[0242] Therefore, among the configurations of the motor-side clutch gear 6C, the boom-side clutch gear 7C, and the cylinder-side clutch gear 8C, the same configurations as those of the motor-side clutch gear 6, the boom-side clutch gear 7, and the cylinder-side clutch gear 8 in the above-described Embodiment 1 are denoted by the same reference numerals as those of the motor-side clutch gear 6, the boom-side clutch gear 7, and the cylinder-side clutch gear 8 in Embodiment 1.

[0243] Regarding 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 appropriately incorporated by reference.

[0244] Figures 8A and 8B are diagrams showing the states of the switching mechanism 5C when the boom connection mechanism 46 performs the removal operation and the insertion operation. Hereinafter, the operation of the switching mechanism 5C will be described with reference to Figures 8A and 8B.

[0245] First, the state of the switching mechanism 5C shown in Figure 8A is the initial state of the switching mechanism 5C. The positions of the motor-side clutch gear 6C, boom-side clutch gear 7C, and cylinder-side clutch gear 8C in the initial state of the switching mechanism 5C are the initial positions. In the initial state (in other words, the second position) of the switching mechanism 5C, 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 Figure 8A is also the state of the switching mechanism 5C before the boom connection mechanism 46 performs the removal operation of the boom connection mechanism 46.

[0247] When the boom connection mechanism 46 performs the removal operation of 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 the first direction (the direction indicated by arrow A1 in Figure 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 arrow A3 in Figure 8A. The rotation directions of the electric motor 41 and the motor-side clutch gear 6C at this time are 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 FIG. 8A (in other words, the first direction).

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

[0251] Thus, in the case of this embodiment, when the motor-side clutch gear 6C rotates in the first rotation direction in the second connection state where 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 the first position (the position of the motor-side clutch gear 6C in FIG. 8B) corresponding to the first connection state where 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 moving the motor-side clutch gear 6C in the axial direction. In other words, in the case of the switching mechanism 5C of this embodiment, the electric motor 41 functions as a clutch actuator (that is, a driving portion).

[0253] In the state shown in FIG. 8B, the switching mechanism 5C is in the first connection state. In the first connection state of the switching mechanism 5C, the motor-side clutch gear 6C engages with the boom-side clutch gear 7C. Note that the state of the switching mechanism 5C shown in FIG. 8A is referred to as the second connection state.

[0254] In the state shown in FIG. 8B, the first motor-side 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 connection state of the switching mechanism 5C is a state in which the rotation of the motor-side clutch gear 6C can be transmitted to the boom-side clutch gear 7C. In the first connection state of the switching mechanism 5C, the motor-side first convex portion 611 of the motor-side first tooth portion 61 in the motor-side clutch gear 6C and the boom-side convex portion 712 of the boom-side tooth portion 711 in the boom-side clutch gear 7C engage with each other in the circumferential direction.

[0256] Further, in the first connection 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) in a state of 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 rotation direction. Then, the motor-side clutch gear 6C further rotates in the first rotation 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. Further, the rotation of the boom-side clutch gear 7C is transmitted to the boom connection 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 contracted 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. Then, the contracted state of the boom connection mechanism 46 is maintained.

[0259] Next, in the state shown in FIG. 8B, the boom connection mechanism 46 performs the entering operation of the boom connection mechanism 46. The entering operation of the boom connection mechanism 46 is automatically performed 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 by a predetermined amount, the rotation of the boom-side clutch gear 7C and the motor-side clutch gear 6C in the second rotation direction stops. Then, the boom connection mechanism 46 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 inserted state.

[0262] In addition, when performing the removal operation of the cylinder connection mechanism 45 from the state shown in FIG. 8B, the control unit (not shown) drives the electric motor 41 in the second rotation direction. Then, the motor-side clutch gear 6C rotates in the direction indicated by 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 (in other words, pushed in the second direction) the boom-side inclined surface 7121 of the boom-side convex portion 712 on the boom-side clutch gear 7C, and the motor-side clutch gear 6C moves in the direction of arrow A2 in FIG. 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 connection state where 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 connection state where 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] Then, the control unit (not shown) further drives the electric motor 41 in the second rotation direction. Then, the motor-side clutch gear 6C rotates further in the direction indicated by arrow A4 in FIG. 8A. The rotation directions of the motor-side clutch gear 6C and the electric motor 41 at this time are the second rotation direction.

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

[0267] In the case of the mobile crane 1C according to the present embodiment having the above configuration, the electric motor 41 has a function as a clutch actuator for moving the motor-side clutch gear 6C of the switching mechanism 5C. Such a configuration contributes to the miniaturization of the switching mechanism 5C.

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

[0269] The mobile crane 1D of the present embodiment is different from the switching mechanism 5C of the mobile crane 1C according to Embodiment 3 described above in the configuration of the switching mechanism 5D. Hereinafter, the differences between the switching mechanism 5D and the switching mechanism 5C will be described.

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

[0272] The first long convex portion 611a on the motor side is provided at two positions in the circumferential direction of the first tooth portion 61D on the motor side. On the other hand, the first short convex portion 611b on the motor side is provided at four positions in the circumferential direction of the first tooth portion 61D on the motor side.

[0273] The two first long convex portions 611a on the motor side and the four first short convex portions 611b on the motor side are provided at equal intervals (60-degree intervals) in the circumferential direction of the first tooth portion 61D on the motor side. The two first long convex portions 611a on the motor side are provided at diagonal positions. In the circumferential direction, two first short convex portions 611b are provided at positions respectively sandwiched by the two first long convex portions 611a on the motor side. Incidentally, the first long convex portion 611a on the motor side may be one. In this case, the first short convex portion 611b on the motor side may be, for example, five.

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

[0275] The second long convex portion 622a on the motor side is provided at two positions in the circumferential direction of the second tooth portion 62D on the motor side. On the other hand, the second short convex portion 622b on the motor side is provided at four positions in the circumferential direction of the second tooth portion 62D on the motor side.

[0276] The two motor-side second long convex portions 622a and the four motor-side second short convex portions 622b are provided at equal intervals (60-degree intervals) in the circumferential direction of the motor-side second tooth portion 62D. The two motor-side second long convex portions 622a are provided at diagonal positions. In the circumferential direction, two motor-side second short convex portions 622b are provided at positions respectively sandwiched by the two motor-side second long convex portions 622a. Incidentally, the number of the motor-side second long convex portions 622a may be one. In this case, the number of the motor-side second short convex portions 622b may be, for example, five.

[0277] The boom-side clutch gear 7D has a boom-side tooth portion 711D. The boom-side tooth portion 711D has a plurality of boom-side convex portions 712 arranged side by side in a circumferentially spaced-apart state.

[0278] The boom-side convex portion 712 has a long convex portion 712a and a short convex portion 712b. The long convex portion 712a corresponds to an example of the first long convex portion. The short convex portion 712b corresponds to an example of the first short convex portion. The length of the long convex portion 712a in the axial direction is longer than the length of the short convex portion 712b in the axial direction. 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 portion 712a is provided at two locations in the circumferential direction of the boom-side tooth portion 711D. On the other hand, the short convex portion 712b is provided at four locations in the circumferential direction of the boom-side tooth portion 711D. That is, the boom-side convex portion 712 has six convex portions.

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

[0281] Further, the cylinder-side clutch gear 8D has a cylinder-side tooth portion 811D. The cylinder-side tooth portion 811D has a plurality of cylinder-side convex portions 812D arranged side by side in a circumferentially spaced-apart state.

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

[0283] The long convex portion 812a is provided at two positions in the circumferential direction of the cylinder-side tooth portion 811D. On the other hand, the short convex portion 812b is provided at four positions in the circumferential direction of the cylinder-side tooth portion 811D. That is, the cylinder-side convex portion 812 has six convex portions. Note that the long convex portion 812a may be one. In this case, the short convex portion 812b may be, for example, five.

[0284] The two long convex portions 812a and the four short convex portions 812b are provided at equal intervals (60-degree intervals) in the circumferential direction of the cylinder-side tooth portion 811D. The two long convex portions 812a are provided at diagonal positions. In the circumferential direction, two short convex portions 812b are provided at positions sandwiched between the two long convex portions 812a.

[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] In the state of the switching mechanism 5D shown in FIG. 9A, when the motor-side clutch gear 6D rotates in the direction indicated by the arrow A4 in FIG. 9A (in other words, the second rotation direction), the pulling operation of the cylinder connection mechanism 45 is performed. At this time, the motor-side clutch gear 6D rotates by a predetermined angle in the second rotation direction.

[0287] In the case of this embodiment, when the motor-side clutch gear 6D rotates by a predetermined angle in the state of the switching mechanism 5D shown in FIG. 9A (that is, the state in which the pulling operation of the cylinder connection mechanism 45 is performed), 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. Such a configuration contributes to suppressing abnormal noise and damage to each gear.

[0288] Specifically, in the state of the switching mechanism 5D shown in FIG. 9A (that is, the state in which the pulling operation of the cylinder connection mechanism 45 is performed), when the motor-side clutch gear 6D rotates by a predetermined angle, the motor-side first long convex portion 611a of the motor-side clutch gear 6D passes through the angular range where the short convex portion 712b of the boom-side clutch gear 7D is provided in the circumferential direction. As a result, 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.

[0289] Also, when operating the boom connection mechanism 46, 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 directions of the electric motor 41 and the motor-side clutch gear 6C are 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) in 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) in 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 FIG. 9A (in other words, the first direction).

[0291] At this time, the moving amount of the motor-side clutch gear 6D is equal to the height H2 of the long convex portion 812a of the cylinder-side convex portion 812D (see FIG. 9A). In this way, when the motor-side clutch gear 6D moves by the height H2 of the long convex portion 812a in the first direction, 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 of FIG. 9B.

[0292] In the case of this embodiment, the motor-side clutch gear 6D is guided by the long convex portion 812a of the cylinder-side clutch gear 8D by the motor-side second long convex portion 622a of the motor-side clutch gear 6D and moves in the first direction. Such a configuration can ensure a large moving stroke of the motor-side clutch gear 6D. Therefore, in the state of FIG. 9B, the motor-side clutch gear 6D can surely engage with the boom-side clutch gear 7D.

[0293] Also, in the state of the switching mechanism 5D shown in FIG. 9B, when the motor-side clutch gear 6D rotates in the direction indicated by the arrow A3 in FIG. 9B (in other words, the first rotation direction), the disengaging operation of the boom connecting mechanism 46 is performed. At this time, the motor-side clutch gear 6D rotates by a predetermined angle in the first rotation direction.

[0294] In the case of this embodiment, in the state of the switching mechanism 5D shown in FIG. 9B (that is, the state in which the disengaging operation of the boom connecting mechanism 46 is performed), when the motor-side clutch gear 6D rotates by a predetermined angle, 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 do not interfere with each other in the circumferential direction. Such a configuration contributes to suppressing abnormal noise and suppressing damage to each gear.

[0295] Specifically, in the state of the switching mechanism 5D shown in FIG. 9B (i.e., the state in which the pulling operation of the boom connection mechanism 46 is performed), when the motor-side clutch gear 6D rotates by a predetermined angle, the motor-side second long convex portion 622a of the motor-side clutch gear 6D passes through the angular range where the short convex portion 812b of the cylinder-side clutch gear 8D is provided in the circumferential direction. As a result, 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 do not interfere with each other in the circumferential direction. The configurations, operations, and effects of the other parts of the mobile crane 1D are the same as those of the mobile crane 1C according to the above-described Embodiment 3.

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

[0297] In the mobile crane 1E of the present embodiment, the configuration of the switching mechanism 5E is different from that of the switching mechanism 5 of the mobile crane 1 according to the above-described Embodiment 1. Hereinafter, the differences between the switching mechanism 5E and the switching mechanism 5 will be described. Among the configurations of the switching mechanism 5E, the same configurations as those of the switching mechanism 5 in Embodiment 1 are denoted by the same reference numerals.

[0298] The switching mechanism 5E includes 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 that of the motor-side clutch gear 6 in Embodiment 1.

[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 the same as that of the gear body 71 in Embodiment 1.

[0300] The shaft portion 72E corresponds to an example of the 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 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 a function of guiding the axial movement of the motor-side clutch gear 6. Also, the shaft portion 72E has a 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 corresponds to an example of the second shaft portion and has a gear body 81 and a shaft portion 82E. The configuration of the gear body 81 is the same as the configuration of the gear body 81 in Embodiment 1.

[0303] The shaft portion 82E corresponds to an example of the 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 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 a function of guiding the axial movement of the motor-side clutch gear 6. Also, the shaft portion 82E has a 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] Further, the tip of the shaft portion 72E of the boom-side clutch gear 7E and the tip of the shaft portion 82E of the cylinder-side clutch gear 8E face each other in the axial direction within the through hole 63, either in contact or with a slight gap therebetween. Such a configuration contributes to reducing the sliding resistance when the tips of the shaft portion 72E and the shaft portion 82E come into contact during the operation of the switching mechanism 5E.

[0306] Incidentally, FIG. 11 is a diagram showing an example of a modified example of the switching mechanism 5E according to the present embodiment. As in the switching mechanism 5E1 shown in FIG. 11, a ball 74 may be provided between the tip of the shaft portion 82E1 and the tip of the shaft portion 72E1. The ball 74 may be made of metal or synthetic resin. Such a configuration also contributes to reducing the sliding resistance when the tip of the shaft portion 72E comes into contact with the ball 74 or when the tip of the shaft portion 82E1 comes into contact with the ball 74 during the operation of the switching mechanism 5E1. The configurations, operations, and effects of the other parts of the mobile crane 1E are the same as those of the mobile crane 1 according to Embodiment 1.

[0307] [Embodiment 6] Next, with reference to FIGS. 12A and 12B, a mobile crane 1F according to Embodiment 6 of the present invention will be described. For the configurations of the cylinder connection mechanism 45 and the boom connection mechanism 46, refer to FIGS. 3A to 3C and FIGS. 4A to 4C.

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

[0309] In the mobile crane 1F of the present embodiment, the configuration of the switching mechanism 5F is different from the configuration of the switching mechanism 5 of the mobile crane 1 according to Embodiment 1 described above. Hereinafter, the configuration of the switching mechanism 5F will be described.

[0310] The operations of the cylinder connection mechanism 45 and the boom connection mechanism 46 are the same as those of the cylinder connection mechanism 45 and the boom connection mechanism 46 of the mobile crane 1 according to the above-described Embodiment 1. Therefore, the descriptions overlapping with those of the above-described Embodiment 1 regarding the configurations and operations of the cylinder connection mechanism 45 and the boom connection mechanism 46 are omitted.

[0311] The switching mechanism 5F selectively engages with one of the connection mechanisms between the cylinder connection mechanism 45 and the boom connection mechanism 46 and transmits the power of the electric motor 41 to one of the connection mechanisms. The switching mechanism 5F includes 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, the boom-side clutch gear 7F, and the cylinder-side clutch gear 8F are substantially the same as the configurations of the motor-side clutch gear 6C, the boom-side clutch gear 7C, and the cylinder-side clutch gear 8C in the above-described Embodiment 3.

[0313] Therefore, among the configurations of the motor-side clutch gear 6F, the boom-side clutch gear 7F, and the cylinder-side clutch gear 8F, the same configurations as those of the motor-side clutch gear 6C, the boom-side clutch gear 7C, and the cylinder-side clutch gear 8C in the above-described Embodiment 3 are denoted by the same reference numerals as those of the motor-side clutch gear 6C, the boom-side clutch gear 7C, and the cylinder-side clutch gear 8C in Embodiment 3.

[0314] Regarding the configurations of such a motor-side clutch gear 6F, a boom-side clutch gear 7F, and a cylinder-side clutch gear 8F, the descriptions of the motor-side clutch gears 6, 6C, the boom-side clutch gears 7, 7C, and the cylinder-side clutch gears 8, 8C in Embodiments 1 and 3 may be appropriately incorporated.

[0315] In the case of this embodiment, the motor-side clutch gear 6F has a clutch-side tooth portion 64 on its outer peripheral surface. The clutch-side tooth portion 64 is provided integrally with the motor-side clutch gear 6F. The clutch-side tooth portion 64 is provided over the entire circumference of the outer peripheral surface of the motor-side clutch gear 6F. The clutch-side tooth portion 64 is preferably straight teeth. Note that the clutch-side portion 64 may be bevel teeth.

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

[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 axially movable relative to the transmission gear 433.

[0318] The configuration of the other motor-side clutch gear 6F is the same as that of the motor-side clutch gear 6C in Embodiment 3. Also, the configuration of the boom-side clutch gear 7F is the same as that of the boom-side clutch gear 7C in Embodiment 3. Also, the configuration of the cylinder-side clutch gear 8F is the same as that of the cylinder-side clutch gear 8C in Embodiment 3.

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

[0320] First, the state of the switching mechanism 5F shown in FIG. 12A is the initial state of the switching mechanism 5F. The positions of the motor-side clutch gear 6F, the boom-side clutch gear 7F, and the cylinder-side clutch gear 8F in the initial state of the switching mechanism 5F are the initial positions. In the initial state (in other words, the second position) of the switching mechanism 5F, 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 connecting mechanism 46 performs the removal operation of the boom connecting mechanism 46.

[0322] When the boom connecting mechanism 46 performs the removal operation of the boom connecting mechanism 46, the control unit (not shown) turns on the electric motor 41. Then, the control unit drives the electric motor 41 in the 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 order of the electric motor 41, the speed reducer 431, the transmission shaft 432, the transmission gear 433, the clutch side tooth portion 64, and the 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 the 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 (in other words, pushed in the first direction) the cylinder side inclined surface 8121 of the cylinder side convex portion 812 on the cylinder side clutch gear 8F, and the motor side clutch gear 6F moves in the direction of arrow A1 in FIG. 12A (in other words, the first direction).

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

[0326] Thus, in the case of this embodiment, when the motor-side clutch gear 6F rotates in the first rotation direction in the second connection state where 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 the first position (the position of the motor-side clutch gear 6F in FIG. 12B) corresponding to the first connection state where 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 a clutch actuator (that is, a driving unit).

[0328] In the state shown in FIG. 12B, the switching mechanism 5F is in the first connection state. In the first connection state of the switching mechanism 5F, the motor-side clutch gear 6F engages with the boom-side clutch gear 7F. Note that the state of the switching mechanism 5F shown in FIG. 12A is referred to as the second connection 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 connection state of the switching mechanism 5F is a state where the rotation of the motor-side clutch gear 6F can be transmitted to the boom-side clutch gear 7F. In the first connection state of the switching mechanism 5F, the motor-side first convex portion 611 of the motor-side first tooth portion 61 on the motor-side clutch gear 6F and the boom-side convex portion 712 of the boom-side tooth portion 711 on the boom-side clutch gear 7F engage in the circumferential direction.

[0331] Further, in the first connection 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) in a state of 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 rotation direction. Then, the motor-side clutch gear 6F further rotates in the first rotation 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. Further, 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 contracted 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. Then, the contracted state of the boom connection mechanism 46 is maintained.

[0334] Next, in the state shown in FIG. 12B, the boom connection mechanism 46 performs the entering operation of the boom connection mechanism 46. The entering operation of the boom connection mechanism 46 is automatically performed 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 the 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 by a predetermined amount, the rotation of the boom-side clutch gear 7F and the motor-side clutch gear 6F in the second rotation direction stops. Then, the boom connection mechanism 46 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 entered state.

[0337] In addition, when performing the removal operation of the cylinder connection mechanism 45 from the state shown in FIG. 12B, the control unit (not shown) drives the electric motor 41 in the second rotation direction. Then, the motor-side clutch gear 6F rotates 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 FIG. 12A (in other words, the second direction).

[0339] In this way, in the case of this embodiment, when the motor-side clutch gear 6F rotates in the second rotation direction in the first connection state where 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 connection state where 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. Then, the motor-side clutch gear 6F rotates further in the direction indicated by arrow A4 in FIG. 12A. The rotation directions of the motor-side clutch gear 6F and the electric motor 41 at this time are the second rotation direction.

[0341] When the motor-side clutch gear 6F rotates in the second rotation direction, the cylinder-side clutch gear 8F rotates in the second rotation direction. And the rotation of the cylinder-side clutch gear 8F is transmitted to the cylinder connection mechanism 45. As a result, the cylinder connection mechanism 45 transitions from the extended state (FIG. 3A) to the contracted state (see FIG. 3C). The retracting operation of the cylinder connection mechanism 45 is automatically performed 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 configuration, the electric motor 41 has a function as a clutch actuator for moving the motor-side clutch gear 6F of the switching mechanism 5F. Such a configuration contributes to the miniaturization of the switching mechanism 5F.

[0343] [Embodiment 7] Next, with reference to FIGS. 13A and 13B, the mobile crane 1G according to Embodiment 7 of the present invention will be described. For the configurations of the cylinder connection mechanism 45 and the boom connection mechanism 46, refer to FIGS. 3A to 3C and FIGS. 4A to 4C.

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

[0345] In the mobile crane 1G of the present embodiment, the configuration of the switching mechanism 5G is different from the configuration of the switching mechanism 5F of the mobile crane 1F according to the above-described Embodiment 6. Hereinafter, the configuration of the switching mechanism 5G will be described.

[0346] Note that the operations of the cylinder connection mechanism 45 and the boom connection mechanism 46 are the same as those of the cylinder connection mechanism 45 and the boom connection mechanism 46 of the mobile crane 1 according to Embodiment 1 described above. Therefore, descriptions overlapping with those of Embodiment 1 above regarding the configurations and operations of the cylinder connection mechanism 45 and the boom connection mechanism 46 will be omitted.

[0347] The switching mechanism 5G selectively engages with one of the connection mechanisms between the cylinder connection mechanism 45 and the boom connection mechanism 46, and transmits the power of the electric motor 41 to one of the connection mechanisms. The switching mechanism 5G includes a motor-side clutch gear 6G, a boom-side clutch gear 7G, and a cylinder-side clutch gear 8G. Further, the switching mechanism 5G has a sleeve portion 66G.

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

[0349] In the case of the present embodiment, the clutch-side tooth portion 64 provided on the outer peripheral surface of the motor-side clutch gear 6G is a male spline.

[0350] The sleeve portion 66G is cylindrical. The sleeve portion 66G has a female spline on its inner peripheral surface. The sleeve portion 66G has a toothed portion on its outer peripheral surface. The sleeve portion 66G is fixed to a fixing portion (not shown). The sleeve portion 66G is rotatable. However, the axial movement of the sleeve portion 66G is restricted by the fixing 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 spline of the sleeve portion 66G meshes with the clutch-side toothed portion 64 of the motor-side clutch gear 6G.

[0352] The motor-side clutch gear 6G is axially movable 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 toothed portion provided on the outer peripheral surface of the sleeve portion 66G 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 toothed portion 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. Then, the rotation of the sleeve portion 66G is transmitted to the motor-side clutch gear 6F. As a result, the motor-side clutch gear 6G rotates.

[0355] The configurations of the other motor-side clutch gear 6G are the same as those of the motor-side clutch gear 6F in Embodiment 6. Also, the configuration of the boom-side clutch gear 7G is the same as that of the boom-side clutch gear 7F in Embodiment 6. Also, the configuration of the cylinder-side clutch gear 8G is the same as that of the cylinder-side clutch gear 8F in Embodiment 6.

[0356] Figures 13A and 13B are diagrams showing the state of the switching mechanism 5G when the boom connection mechanism 46 performs the pulling-out operation and the insertion operation. Hereinafter, with reference to Figures 13A and 13B, the operation of the switching mechanism 5G will be described.

[0357] First, the state of the switching mechanism 5G shown in Figure 13A is the initial state of the switching mechanism 5G. The positions of the motor-side clutch gear 6G, the boom-side clutch gear 7G, and the cylinder-side clutch gear 8G in the initial state of the switching mechanism 5G are the initial positions. In the initial state (in other words, the second position) of the switching mechanism 5G, 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 Figure 13A is also the state of the switching mechanism 5G before the boom connection mechanism 46 performs the pulling-out operation of the boom connection mechanism 46.

[0359] When the boom connection mechanism 46 performs the pulling-out operation of the boom connection mechanism 46, the control unit (not shown) turns on the electric motor 41. Then, the control unit drives the electric motor 41 in the 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 order of the electric motor 41, the speed reducer 431, the transmission shaft 432, the transmission gear 433, the sleeve portion 66G, the clutch-side tooth portion 64, and the motor-side clutch gear 6G. Then, the motor-side clutch gear 6G rotates in the direction of arrow A3 in Figure 13A. The rotation direction of the motor-side clutch gear 6G at this time is referred to as the 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 in the motor-side clutch gear 6G is guided (in other words, pushed in the first direction) by the cylinder-side inclined surface 8121 of the cylinder-side convex portion 812 in the cylinder-side clutch gear 8G.

[0362] In the case of this embodiment, the motor-side clutch gear 6G is axially movable relative to the sleeve portion 66G. Therefore, the motor-side clutch gear 6G moves in the direction of arrow A1 in Fig. 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 convex portion 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 convex portion 812, the motor-side clutch gear 6G engages with the boom-side clutch gear 7G (see Fig. 13B). The position of the motor-side clutch gear 6G in the switching mechanism 5G in the state shown in Fig. 13B is the first position.

[0364] Thus, in the case of this embodiment, when the motor-side clutch gear 6G rotates in the first rotation direction in the second connection state where 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 the first position corresponding to the first connection state where the power of the electric motor 41 can be transmitted to the boom-side clutch gear 7G (in other words, the first transmission member) (the position of the motor-side clutch gear 6G in Fig. 13B).

[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 a clutch actuator (that is, a drive unit).

[0366] In the state shown in Fig. 13B, the switching mechanism 5G is in the first connection state. In the first connection state of the switching mechanism 5G, the motor-side clutch gear 6G engages with the boom-side clutch gear 7G. Note that the state of the switching mechanism 5G shown in Fig. 13A is referred to as the second connection 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 connection state of the switching mechanism 5G is a state in which the rotation of the motor-side clutch gear 6G can be transmitted to the boom-side clutch gear 7G. In the first connection state of the switching mechanism 5G, the motor-side first convex portion 611 of the motor-side first tooth portion 61 in the motor-side clutch gear 6G and the boom-side convex portion 712 of the boom-side tooth portion 711 in the boom-side clutch gear 7G are engaged in the circumferential direction.

[0369] Further, in the first connection 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 are engaged (specifically, abutted) in a state of facing each other in the axial direction.

[0370] Next, in the state shown in FIG. 13B, the control unit (not shown) further drives the electric motor 41 in the first rotation direction. Then, the motor-side clutch gear 6G further rotates in the first rotation 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. Further, the rotation of the boom-side clutch gear 7G is transmitted to the boom connection mechanism 46 (see FIG. 4A).

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

[0372] Next, in the state shown in FIG. 13B, the boom connection mechanism 46 performs the entering operation of the boom connection mechanism 46. The entering operation of the boom connection mechanism 46 is automatically performed based on the urging force of the second urging 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 the arrow A4 in FIG. 13B based on the urging force of the second urging mechanism 463. The rotation direction at this time is the second rotation direction.

[0374] When the boom-side clutch gear 7G rotates by a predetermined amount, the rotation of the boom-side clutch gear 7G and the motor-side clutch gear 6G in the second rotation direction stops. Then, the boom connection mechanism 46 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 inserted state.

[0375] In addition, when performing the removal operation of the cylinder connection mechanism 45 from the state shown in FIG. 13B, 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 order of the electric motor 41, the speed reducer 431, the transmission shaft 432, the transmission gear 433, the sleeve portion 66, the clutch-side tooth portion 64, and the motor-side clutch gear 6G. As a result, the motor-side clutch gear 6G rotates in the direction indicated by the 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 in the motor-side clutch gear 6G is guided by (in other words, pushed in the second direction) the boom-side inclined surface 7121 of the boom-side convex portion 712 in the boom-side clutch gear 7G, and the motor-side clutch gear 6G moves in the direction of the arrow A2 in FIG. 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 connection state where 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 connection state where 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. Then, the motor-side clutch gear 6G rotates further in the direction indicated by arrow A4 in FIG. 13A. The rotation directions of the motor-side clutch gear 6G and the electric motor 41 at this time are the second rotation direction.

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

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

[0381] <Supplementary Note> The technical ideas disclosed in the specification and the drawings include inventions obtained by arbitrarily combining the various configurations described in the above embodiments. In particular, the technical ideas disclosed in the specification and the drawings include inventions obtained by applying the various configurations disclosed in the specification and the drawings to the above basic configuration in any combination.

Industrial Applicability

[0382] The crane according to the present invention is not limited to a rough terrain crane, and may be, for example, various mobile cranes such as an all terrain crane, a truck crane, or a loading truck crane (also referred to as a cargo crane). Further, the crane according to the present invention is not limited to a mobile crane, and may be other cranes provided with a telescopic boom.

Explanation of Reference Numerals

[0383] 1, 1B, 1C, 1D, 1E, 1F, 1G Mobile Crane 10 Traveling Body 12 Slewing Platform 14 Telescopic Boom 141 Tip Boom 1411, 1412 Cylinder Pin Receiving Parts 141b Boom Pin Receiving Part 142 Intermediate Boom 142a Cylinder Pin Receiving Part 142b First Boom Pin Receiving Part 142c Second Boom Pin Receiving Part 142d Third Boom Pin Receiving Part 143 Base Boom 144a, 144b Boom Connecting Pins 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 Connecting Mechanism 451 First Rack Bar 452 First Gear Mechanism 453 Second Gear Mechanism 454A, 454B Cylinder Connecting Pins 455 First Biasing Mechanism 455a, 455b Coil Springs 46 Boom Connecting Mechanism 461a, 461b Second Rack Bars 461g, 461h Locking Claw Parts 462 Synchronous Gear 463 Second Biasing Mechanism 463a, 463b Coil Springs 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 ball 8, 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 Driving Part 92a First Spring 93a First Pressing Part 930a Through-Hole 91b Second Driving Part 92b Second Spring 93b Second Pressing Part 930b Through-Hole 99 Fixing Part

Claims

1. A telescopic boom having a plurality of booms and telescoping by a telescopic cylinder, a first connecting mechanism that connects the boom and the telescopic cylinder and releases the connection by a motor, a second connecting mechanism that connects adjacent booms and releases the connection by the motor, a switching mechanism that moves in the axial direction and is selectively connected to one of the first connecting mechanism and the second connecting mechanism, and has a motor-side transmission member that transmits the power of the motor to the one connecting mechanism, a working machine.

2. The rotation direction of the motor in a state where the power is transmitted to the first connecting mechanism is the same as the rotation direction of the motor in a state where the power is transmitted to the second connecting mechanism, The working machine according to Claim 1.

3. The rotation direction of the motor in a state where the power is transmitted to the first connecting mechanism is opposite to the rotation direction of the motor in a state where the power is transmitted to the second connecting mechanism, The working machine according to Claim 1.

4. The switching mechanism, a first transmission member connected to the first connecting mechanism, a second transmission member connected to the second connecting mechanism, and further has, The motor-side transmission member, engages with the first transmission member in a first state of transmitting the power to the first connecting mechanism, engages with the second transmission member in a second state of transmitting the power to the second connecting mechanism, The working machine according to Claim 1.

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

6. 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 both the first transmission member and the second transmission member when placed at a third position between the first position and the second position, The working machine according to Claim 4.

7. 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, 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, The working machine according to Claim 4.

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

9. 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 a first tooth portion that engages with the motor-side first tooth portion in the first state. The second transmission member has a second tooth portion that engages with the motor-side second tooth portion in the second state. The working machine according to claim 8.

10. 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 plurality of the first tooth portions has 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 plurality of the second tooth portions has 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. The motor-side transmission member moves to the first position when the motor-side second long convex portion is guided by the second long convex portion, and moves to the second position when the motor-side first long convex portion is guided by the first long convex portion. The working machine according to claim 9.

11. In the first state, within the 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. In the second state, within the 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. The working machine according to claim 10.

12. 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. The tip surface of the first shaft portion and the tip surface of the second shaft portion face each other in a state where they can contact each other within the motor-side transmission member. The working machine according to claim 5.

13. It further includes a ball provided within the motor-side transmission member. The first transmission member has a first shaft portion inserted into the motor-side transmission member. The second transmission member has a second shaft portion inserted into the motor-side transmission member. The tip surface of the first shaft portion and the tip surface of the second shaft portion face each other within the motor-side transmission member and are in contact with the ball, respectively. The working machine according to claim 4.

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

15. The drive unit 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. The elastic member biases the motor-side transmission member toward the one coupling mechanism in a state where the power of the motor can be transmitted to the one coupling mechanism. The working machine according to claim 14.

16. The motor has a function as a drive unit that moves the motor-side transmission member in the axial direction. The working machine according to claim 1.

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