Work machine

Abstract

Problem: To provide a work machine capable of suppressing an 5 increase in weight and improving visibility. Resolution Means: A work machine (1) comprising: a lower traveling body (2); an upper swing body (3) rotatably supported on the upper portion of the lower traveling body (2); and a cable reel (40) that is disposed substantially concentrically with the center of rotation of the upper swing body (3) and is configured to wind and unwind a power transmission cable (37) by rotation so as to supply power to a power receiving unit.

Description

[0001] 24-0702W001

[0002] -1-

[0003] Description

[0004] WORK MACHINE

[0005] Technical Field

[0006] The present invention relates to a work machine equipped with a cable reel configured to wind and unwind a power transmission cable by rotation.

[0007] Conventionally, in electric excavators that operate while remaining connected to a power transmission cable, a cable reel is known that automatically rotates around a vertical axis to wind and unwind the power transmission cable and is disposed on a track frame of a lower traveling body so as not to impair vehicle mobility, operability, or workability, etc. In such cases, the cable reel is positioned between left and right track frames, behind the axis of rotation of an upper swing body (see, for example, Patent Documents 1 to 3).

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1 : Japanese Unexamined Patent Application Publication No. 2003-96820.

[0011] Patent Document 2: Japanese Unexamined Utility Model Application Publication No. 6-67551.

[0012] Patent Document 3 : Japanese Unexamined Utility Model Application Publication No. 7-12553.

[0013] Summary of the Invention

[0014] Problems to be Solved by the Invention

[0015] In the above configuration, since the center of gravity of the cable reel is located distant from the track frame to which it is mounted, it is necessary 24-0702W001

[0016] -2- to add a beam, etc. in order to enhance the strength of the support structure for the cable reel, resulting in an increase in weight. Moreover, when the upper swing body is rotated to face rearward, the cable reel is positioned in such a way that it obstructs the space between the left and right tracks, thereby impairing rearward lower visibility. Furthermore, since the cable reel protrudes into the working range of the front work machine, there is a concern that it may come into contact with the front work machine and become damaged.

[0017] Moreover, in order to wind and unwind the power transmission cable in accordance with the traveling of the vehicle, the cable reel itself rotates. However, since the base end of the power transmission cable wound onto the cable reel needs to be connected to the vehicle body, a slip ring is required to allow free rotation between the cable reel and the vehicle body so that the power transmission cable does not become twisted. Furthermore, since the motor driven by the supplied electric power is disposed on the upper swing body, the power transmission cable needs to be electrically connected from the lower traveling body to the upper swing body. Therefore, another slip ring is required to allow free rotation between the lower traveling body and the upper swing body so that the power transmission cable does not become twisted when the upper swing body rotates.

[0018] The present invention has been created in view of such circumstances, with the object of providing a work machine capable of suppressing an increase in weight and improving visibility.

[0019] Means for Solving the Problem

[0020] The work machine according to the present invention comprises: a lower traveling body; an upper swing body rotatably supported on the upper portion of the lower traveling body; and a cable reel that is disposed substantially concentrically with the center of rotation of the upper swing body and is configured to wind and unwind a power transmission cable by rotation so as to supply power to a power receiving unit. 24-0702W001

[0021] -3-

[0022] Effect of the Invention

[0023] According to the present invention, it is possible to suppress an increase in weight and improve visibility.

[0024] Brief Description of the Drawings

[0025] Fig. l is a side view schematically illustrating a part of Embodiment 1 of a work machine according to the present invention.

[0026] Fig. 2 is a front view schematically illustrating a part of the same work machine.

[0027] Fig. 3 is a plan view schematically illustrating a part of the same work machine.

[0028] Fig. 4 is a side view schematically illustrating a part of Embodiment 2 of the work machine according to the present invention.

[0029] Fig. 5 is a side view schematically illustrating a part of Embodiment 3 of the work machine according to the present invention.

[0030] Detailed Description of the Invention

[0031] Hereinafter, the present invention will be described in detail based on Embodiment 1 illustrated in Figs. 1 to 3, Embodiment 2 illustrated in Fig. 4, and Embodiment 3 illustrated in Fig. 5.

[0032] First, the embodiment illustrated in Figs. 1 to 3 will be described.

[0033] In Figs. 1 to 3, reference numeral 1 denotes a work machine. The work machine l is a swing-type work machine having a lower traveling body 2 and an upper swing body 3, and in the illustrated example, a hydraulic excavator is depicted as an example. The work machine 1 of this embodiment is a wired electric hydraulic excavator that operates by receiving electric power via a cable from an externally located power supply unit (power supply equipment) PS.

[0034] The lower traveling body 2 is exemplified by a track-type traveling device. The lower traveling body 2 includes a frame 5. The frame 5 integrally includes a pair of left and right track frames 6 and a main frame 7 at the 24-0702W001

[0035] -4- center portion where the track frames 6 are connected. Each track frame 6 is formed in an elongated shape along the traveling direction of the lower traveling body 2. One or more carrier rollers and multiple track rollers are rotatably supported on the upper and lower portions of each track frame 6. Moreover, a sprocket, which is a drive wheel driven by a traveling motor 11, is mounted on one longitudinal end of each track frame 6, while an idler, which is a driven wheel, is rotatably supported at the other longitudinal end of each track frame 6. The traveling motor 11 may be, for example, a fluid pressure motor (hydraulic motor). In addition, an endless track 14 is wound around the carrier rollers, track rollers, sprocket, and idler.

[0036] Moreover, a bearing section 16 for pivotally supporting the upper swing body 3 is provided on the main frame 7. In other words, the bearing section 16 forms the center of rotation of the upper swing body 3. The bearing section 16 extends in the vertical direction, that is, along the up-down axis.

[0037] The upper swing body 3 includes a swing frame 20. Mounted on the swing frame 20 is a cab 21 that forms a driver's compartment where the operator sits, a front work machine 22, which is a working apparatus operable by the operator, a tank 23 such as a hydraulic oil tank that stores hydraulic oil, as well as a counterweight, etc.

[0038] Moreover, a swing bearing 25 is also provided at the bottom of the swing frame 20. The swing bearing 25 rotatably supports the outer peripheral portion of the bearing section 16. One or more swing motors are meshed with the swing bearing 25, with the upper swing body 3 rotating relative to the lower traveling body 2 as the swing motor rotates. The swing motor may be, for example, a hydraulic motor; however, an electric motor may also be used.

[0039] A swivel joint (rotary joint) 28 is coaxially disposed on the bearing section 16. The swivel joint 28 has a dual structure including a rotor and an outer case, with the rotor being rotatable relative to the outer case. One of either the rotor or outer case of the swivel joint 28 is attached to the main frame 7 of the lower traveling body 2, while the other of the rotor or outer case is attached to the 24-0702W001

[0040] -5- swing frame 20 of the upper swing body 3. Through connection passages formed between the rotor and the outer case, a hydraulic oil passage 30 on the lower traveling body 2 side and a hydraulic oil passage 31 on the upper swing body 3 side are connected in a fluid-tight manner.

[0041] In this embodiment, since the traveling motor 11 is a hydraulic motor, a hydraulic oil passage 30 is connected to the traveling motor 11. Moreover, a hydraulic oil passage 31 is connected to the swivel joint 28 and to a hydraulic pump 34 disposed on the upper swing body 3. The hydraulic pump 34 discharges and supplies hydraulic oil, stored in a hydraulic oil tank, via a control valve to hydraulic actuators such as hydraulic cylinders that operate hydraulic motors such as the traveling motor 11 and the swing motor and / or the front work machine 22, etc.

[0042] In this embodiment, the hydraulic pump 34 is driven by an electric motor 35. The electric motor 35 is a power receiving unit that operates by receiving power from a power supply unit PS.

[0043] Electric power from the power supply unit PS is supplied via a power transmission cable 37. The power transmission cable 37 is configured by, for example, integrally retaining a thin cable for low voltage and a thick cable for high voltage within a flexible tube. The work machine 1 of this embodiment basically operates with the power transmission cable 37 still connected. Therefore, the work machine 1 includes a cable reel 40 capable of adjusting the length of the power transmission cable 37 by winding and unwinding it by rotation, in accordance with the positional relationship and moving speed relative to the power supply unit PS.

[0044] A horizontal-rotation type (vertical-axis) cable reel 40 having an axis of rotation along the vertical direction is used. The cable reel 40 is disposed substantially concentrically with the center of rotation of the upper swing body 3. In other words, the cable reel 40 is coaxial with the bearing section 16, the swing bearing 25, the swivel joint 28, etc. 24-0702W001

[0045] -6-

[0046] In this embodiment, the cable reel 40 is disposed, for example, between the lower traveling body 2 and the upper swing body 3. The cable reel 40 is located between the frame 5 and the swing frame 20. In the illustrated example, the cable reel 40 is mounted on the lower portion of the swing frame 20 of the upper swing body 3 and is located above the lower traveling body 2. The cable reel 40 has larger inner and outer diameters than the swing bearing 25 and is disposed substantially concentrically with the swing bearing 25 so as to surround the outer periphery of the swing bearing 25. Accordingly, the cable reel 40 is configured with a large diameter so as not to interfere with surrounding components. At the same time, the cable reel 40 has an outer diameter dimension that fits within the width of the upper swing body 3 (swing frame 20) and does not protrude from the upper swing body 3 when viewed from above.

[0047] In the illustrated example, the cable reel 40 is mounted so as to hang from the lower portion of the upper swing body 3 (swing frame 20) via a bearing 41. That is, in this embodiment, the bearing 41 is disposed on the upper swing body 3 (swing frame 20). The cable reel 40 integrally includes an annular gear portion 42 and is configured so as to be rotated by a motor 43 that meshes with the gear portion 42 via a speed reducer. In this embodiment, the gear portion 42 is shaped so as not to protrude beyond the outer profile of the cable reel 40, is integrated with the upper portion of the cable reel 40, and is meshed with the motor 43 mounted on the lower portion of the upper swing body 3 (swing frame 20). Accordingly, the cable reel 40 can rotate independently of the upper swing body 3. Note that it is also possible to dispose the gear portion 42 on the upper swing body 3 side and the motor 43 on the cable reel 40 side.

[0048] The bearing 41, for example, has a structure that is vertically inverted relative to the swing bearing 25.

[0049] The motor 43 is disposed at a position inside the outer profile of the cable reel 40. The motor 43 may be selected to be either an electric motor or a hydraulic motor depending on the installation arrangement. The drive of the motor 43 is controlled via a control unit 45, with the cable reel 40 automatically 24-0702W001

[0050] -7- rotating so that the power transmission cable 37 is reeled out from or wound onto the cable reel 40. The control unit 45 includes an inverter, etc. and outputs a control signal for controlling the drive of the motor 43.

[0051] In this embodiment, since the cable reel 40 is positioned between the lower traveling body 2 and the upper swing body 3, it is not necessary to fix the winding direction of the power transmission cable 37, so the power transmission cable 37 can be led out in an arbitrary direction from such as the space between the lower traveling body 2 and the upper swing body 3. The rotation angle of the cable reel 40 is controlled so that the winding direction is directed toward the power supply unit PS in accordance with the posture and position of the work machine 1. Regarding the winding direction of the cable reel 40, when a reel guide is provided on the cable reel 40, the direction of the reel guide becomes the winding direction. For example, in order to prevent the power transmission cable 37 from contacting the track 14, a track cover may be provided to cover the track 14 or a cable guide may be provided to support the power transmission cable 37 in a floating state with respect to the track 14 outside the track 14.

[0052] The end of the power transmission cable 37 wound around the cable reel 40 is electrically and mechanically connected to a slip ring 47 disposed substantially concentrically with the bearing 41 (supporting the cable reel 40) and the swing bearing 25 and this slip ring 47 is electrically connected via a wire 48 to a power receiving unit such as the electric motor 35 disposed on the upper swing body 3. That is, the power transmission cable 37 is electrically connected to the interior of the upper swing body 3 via the slip ring 47, thereby supplying electric power to the upper swing body 3. In other words, in this embodiment, the slip ring 47 is disposed on the upper swing body 3 (swing frame 20).

[0053] The slip ring 47 is configured such that a brush makes sliding contact with an annular electric circuit. In this embodiment, the slip ring 47 has an electric circuit disposed so as to surround the outer side of the swing bearing 25 and is positioned at a position inside the bearing 41 and the cable reel 40. The 24-0702W001

[0054] -8- power receiving unit is electrically connected to the electric circuit, while the power transmission cable 37 is electrically connected to the brush. In this embodiment, since the power transmission cable 37 is directly connected to the upper swing body 3 while bypassing the lower traveling body 2, the power transmission cable 37 can be electrically connected to the inside of the upper swing body 3 using only a single slip ring 47.

[0055] In addition, the control unit 45 monitors the posture and position of the work machine 1 via sensors, etc., and outputs a control signal accordingly. When the work machine 1 moves away from the power supply unit PS, the motor 43 rotates the cable reel 40 to feed out the power transmission cable 37 in accordance with the traveling speed. When approaching the power supply unit PS, the motor 43 rotates the cable reel 40 to wind up the power transmission cable 37. Thus, the connection between the work machine 1 and the power supply unit PS via the power transmission cable 37 is maintained, allowing the work machine 1 to operate while the power receiving unit is powered via the power transmission cable 37 from the power supply unit PS. Moreover, the control unit 45 controls the operation of the motor 43 based on the posture and position of the work machine 1, thereby controlling the rotation angle of the cable reel 40 so that the winding direction is toward the power supply unit PS.

[0056] As described above, by disposing the cable reel 40 substantially concentrically with the center of rotation of the upper swing body 3, this embodiment can adopt a structure in which the cable reel 40 is suspended from the upper swing body 3 via the bearing 41, eliminating the need for an additional reinforced beam structure to support the cable reel 40 and thereby suppressing an increase in weight. Moreover, since the cable reel 40 is disposed at the center of rotation of the upper swing body 3, the cable reel 40 can be accommodated within the width of the upper swing body 3 and prevented from protruding beyond the upper swing body 3 when viewed from above. Accordingly, even when the upper swing body 3 rotates, the cable reel 40 does not obstruct the 24-0702W001

[0057] -9- operator’s field of view, thereby improving visibility and preventing the front work machine 22 from coming into contact with the cable reel 40.

[0058] Moreover, in conventional examples, for instance, where a cable reel is disposed between the rear portions of track frames, the outer diameter of the cable reel is limited to a size that avoids interference with the swing bearing or track. In contrast, the cable reel 40 in this embodiment is located around the swing bearing 25 and above the lower traveling body 2, allowing the outer diameter thereof to be increased without interference from surrounding components, thereby securing the necessary cable length even with fewer windings. Furthermore, by increasing the outer diameter of the cable reel 40, it becomes possible to wind the power transmission cable 37 without stacking it vertically, in addition to reducing the vertical thickness of the cable reel 40 to approximately the thickness of a single layer of the power transmission cable 37. That is, in the case of a horizontally oriented cable reel, it is difficult to reduce the height below the minimum bend diameter of the power transmission cable, and in particular, since the minimum bend radius for high-voltage power transmission cables is very large, the height becomes even greater. In this embodiment, the height of the cable reel 40 can be significantly reduced, resulting in a simpler and lighter structure that also prevents tangling of the power transmission cable 37.

[0059] Furthermore, if the winding direction of the power transmission cable is fixed on the cable reel, turning or rotating the cable reel in a direction different from that of the power supply unit can cause the power transmission cable to bend at the end of the cable reel or reel guide, and if force is applied in this bent state, the bending radius will fall below the minimum bending radius of the power transmission cable, potentially causing the power transmission cable to break. In contrast, in the present embodiment, since it is not necessary to fix the winding direction of the power transmission cable 37 on the cable reel 40, even if the upper swing body 3 rotates or the lower traveling body 2 changes direction, the winding direction of the power transmission cable 37 can always be directed 24-0702W001

[0060] -10- toward the power supply unit PS, thereby preventing damage caused by bending of the power transmission cable 37.

[0061] Since only one expensive slip ring 47 is required, the work machine 1 can be configured at a lower cost.

[0062] Moreover, by positioning the slip ring 47 on the upper swing body 3, where space is more available, the size of the slip ring 47 can be significantly reduced.

[0063] Next, Embodiment 2 illustrated in Fig. 4 will be described. Note that components identical to those in the embodiments illustrated in Figs. 1 to 3 are denoted by the same reference numerals, so a detailed explanation thereof will be omitted.

[0064] In this embodiment, the cable reel 40 is disposed substantially concentrically with the center of rotation of the upper swing body 3 and is positioned between the lower traveling body 2 and the upper swing body 3, located on the upper portion of the lower traveling body 2 (main frame 7) via a bearing 41. That is, the cable reel 40 and the bearing 41 are disposed on the lower traveling body 2 (main frame 7).

[0065] Moreover, a gear portion 42 is formed on the lower portion of the cable reel 40, with a motor 43 that meshes with the gear portion 42 disposed on the lower traveling body 2 (main frame 7). Preferably, the motor 43 is disposed on the rear side of the lower traveling body 2 (main frame 7). Thus, by driving the motor 43, the cable reel 40 can rotate independently of the lower traveling body 2.

[0066] The slip ring 47 is disposed substantially concentrically with the bearing 41 and the swing bearing 25. In this embodiment, the slip ring 47 is disposed on the lower traveling body 2 (main frame 7) at a position inside the bearing 41.

[0067] The swivel joint 28 has a wire insertion hole 50 formed along the central axis of the rotor, with a wire 51 electrically and mechanically connected to the slip ring 47 inserted through the wire insertion hole 50. Moreover, on the 24-0702W001

[0068] -11- upper side of the swivel joint 28, a slip ring 52 is coaxially disposed with the swivel joint 28, with the wire 51 inserted through the wire insertion hole 50 electrically and mechanically connected to the slip ring 52. In addition, the slip ring 52 is electrically connected, via a wire 53, to a power receiving unit such as the electric motor 35 inside the upper swing body 3. Thus, the power transmission cable 37 is electrically connected to the power receiving unit via the slip rings 47 and 52, with power supplied from the power supply unit PS to the power receiving unit.

[0069] In this embodiment, as described above, by disposing the cable reel 40 substantially concentrically with the center of rotation of the upper swing body 3 and employing a configuration similar to that of Embodiment 1, it is possible to adopt a structure in which the cable reel 40 is mounted on the existing main frame 7 of the lower traveling body 2 via the bearing 41. This eliminates the need to add a reinforced beam structure to support the cable reel 40, thereby suppressing an increase in weight. In addition, since the cable reel 40 is disposed within the width of the upper swing body 3, it does not protrude beyond the upper swing body 3 when viewed from above. Accordingly, even when the upper swing body 3 swings, the cable reel 40 does not obstruct the operator's field of view, improving visibility and preventing the front work machine 22 from coming into contact with the cable reel 40. As a result, the same operational advantages as those in Embodiment 1 can be achieved.

[0070] Moreover, in this embodiment, although slip rings 47 and 52 are required, it is not necessary to fix the winding direction of the power transmission cable 37 as in Embodiment 1, so the winding direction of the power transmission cable 37 can always be oriented toward the power supply unit PS, thereby preventing damage caused by bending of the power transmission cable 37.

[0071] Next, Embodiment 3 illustrated in Fig. 5 will be described. Note that components identical to those in the other embodiments are denoted by the same reference numerals, so descriptions thereof have been omitted. 24-0702W001

[0072] -12-

[0073] In this embodiment, the cable reel 40 is disposed substantially concentrically with the center of rotation of the upper swing body 3 and is positioned between the track frames 6 at the lower portion of the main frame 7 of the lower traveling body 2. That is, a cable reel 40 sized to fit within the width between the left and right tracks 14 is disposed below the swivel joint 28, at the lower portion of the main frame 7 of the lower traveling body 2, and substantially concentrically with the swing bearing 25. The cable reel 40 is suspended, for example, via a bearing 41 having the same structure as that in Embodiment 1, from the lower portion of the lower traveling body 2 (main frame 7).

[0074] A gear portion 42 is formed on the lower portion of the lower traveling body 2, with a motor 43 meshing with the gear portion 42 mounted on the cable reel 40. In this example, the motor 43 is an electric motor. By driving the motor 43, the cable reel 40 can rotate independently of the lower traveling body 2. Note that if the motor 43 is a hydraulic motor, for example, the gear portion 42 may be provided on the cable reel 40 side and the motor 43 on the lower traveling body 2 side.

[0075] Moreover, one end of the power transmission cable 37 wound around the cable reel 40 is inserted through a wire insertion hole 50 of the swivel joint 28 and is electrically and mechanically connected to a slip ring 52 that is disposed coaxially on the upper side of the swivel joint 28. In addition, the slip ring 52 is electrically connected, via a wire 53, to a power receiving unit such as the electric motor 35 inside the upper swing body 3. Thus, the power transmission cable 37 is electrically connected to the power receiving unit via the slip ring 52, with power supplied from the power supply unit PS to the power receiving unit. Therefore, in this embodiment, as in Embodiment 1, only one slip ring 52 is needed to electrically connect the power transmission cable 37 to the power receiving unit within the upper swing body 3. However, since the cable reel 40 is positioned between the track frames 6, it is not possible to always orient the winding direction of the power transmission cable 37 toward the power supply unit PS and the winding direction of the power transmission cable 37 is 24-0702W001

[0076] -13- essentially fixed between the track frames 6, so it is desirable to provide a guide to prevent the power transmission cable 37 from contacting the track 14.

[0077] Preferably, the bearing 41 and the swivel joint 28 are connected by a flexible joint 55. The flexible joint 55 includes, for example, a flexible tube connected to the bearing 41 and another flexible tube connected to the swivel joint 28, which are disposed coaxially, along with a pin that secures them in place, with the pin radially penetrating both tubes, loosely securing them together. The power transmission cable 37 is inserted through the inside of the tube.

[0078] In this embodiment, as described above, by disposing the cable reel 40 substantially concentrically with the center of rotation of the upper swing body 3 and employing a configuration similar to that of Embodiment 1, it is possible to adopt a structure in which the cable reel 40 is mounted on the existing main frame 7 of the lower traveling body 2 via the bearing 41. This eliminates the need to add a reinforced beam structure to support the cable reel 40, thereby suppressing an increase in weight. In addition, since the cable reel 40 is disposed within the width of the upper swing body 3, it does not protrude beyond the upper swing body 3 when viewed from above. Accordingly, even when the upper swing body 3 swings, the cable reel 40 does not obstruct the operator's field of view, improving visibility and preventing the front work machine 22 from coming into contact with the cable reel 40. As a result, the same operational advantages as those in Embodiment 1 can be achieved.

[0079] Moreover, since the cable reel 40 is suspended from the lower traveling body 2 (main frame 7), there is no need to provide vertical space between the lower traveling body 2 and the upper swing body 3 to dispose the cable reel 40, so the overall height of the work machine 1 can be reduced.

[0080] Furthermore, in this embodiment, the cable reel 40, the power transmission cable 37, the rotating portion of the bearing 41, the flexible joint 55, and the rotating portion of the slip ring 52 rotate as a unit. The torque of the cable reel 40 is transmitted to the slip ring 52. The combined weight is supported by the 24-0702W001

[0081] -14- bearing 41 that connects the cable reel 40 to the lower traveling body 2 (main frame 7). Even if there is slight misalignment among the central axes of the swivel joint 28, the bearing 41, and the swing bearing 25, the misalignment can be absorbed by providing flexible structures such as a soft cable tube that houses the power transmission cable 37 and the flexible joint 55.

[0082] Moreover, since only one expensive slip ring 52 is required, the work machine 1 can be configured at a lower cost.

[0083] In addition, although the cable reel 40 must be sized to fit within the width between the left and right tracks 14, since there is no swing bearing 25 inside the cable reel 40, the inner diameter of the cable reel 40 can be reduced, allowing sufficient cable length to be accommodated.

[0084] Note that in each embodiment, a cover for shielding the cable reel 40 from below may be provided on the lower traveling body 2. Further, for example, the bearing 41 of the cable reel 40 may be disposed on the lower portion of the lower traveling body 2 (main frame 7) and the cable reel 40 may be disposed inside the frame 5 of the lower traveling body 2.

[0085] The power receiving unit supplied with electric power from the power transmission cable 37 is not limited to the electric motor 35, but may be any other power receiving unit mounted on the upper swing body 3. In this case, the hydraulic pump 34 is not limited to one driven by the electric motor 35, but may also be one driven by an engine.

[0086] Industrial

[0087] The present invention is applicable, for example, to industries engaged in the manufacture and sale of wired electric work machines.

[0088] 1 Work machine

[0089] 2 Lower traveling body

[0090] 3 Upper swing body -0702W001

[0091] -15-

[0092] 22 Front work machine serving as a working apparatus

[0093] 34 Hydraulic pump

[0094] 35 Electric motor serving as a power receiving unit

[0095] 37 Power transmission cable 40 Cable reel

[0096] 47,52 Slip ring

[0097] PS Power supply unit

Claims

24-0702W001-16-Claims1. A work machine comprising: a lower traveling body; an upper swing body rotatably supported on the upper portion of the lower traveling body; and a cable reel that is disposed substantially concentrically with the center of rotation of the upper swing body and is configured to wind and unwind a power transmission cable by rotation so as to supply power to a power receiving unit.

2. The work machine according to claim 1, comprising a single slip ring provided to electrically connect the power transmission cable and the power receiving unit.

3. The work machine according to claim 1, wherein the cable reel is disposed between the lower traveling body and the upper swing body, with the rotation angle of the cable reel controlled such that the winding direction of the power transmission cable faces a power supply unit.

4. The work machine according to claim 1, comprising a working apparatus operably disposed on the upper swing body.

5. The work machine according to claim 1, comprising: a hydraulic pump that discharges hydraulic oil; and an electric motor, serving as a power receiving unit, which is supplied with power via the power transmission cable and drives the hydraulic pump.

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