Electric power unit and work equipment

Abstract

To provide an electric power unit that can have the center of gravity lowered to be closer to a wheel shaft of a work machine to improve stability, and the work machine comprising the electric power unit.SOLUTION: An electric power unit comprises a motor device having a rotary shaft, a controller for controlling the operation of the motor device, and a battery device for driving the motor device, and the battery device is supported detachably by the motor device to cover the motor device from above and an upper part on one side of the motor device when viewed from the shaft direction of the rotary shaft.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to an electric power unit and a working machine equipped with the electric power unit.

Background Art

[0002] As a drive source for working machines such as management machines and tillage tractors for managing soil, a general-purpose air-cooled single-cylinder engine may be used. In recent years, with the tightening of exhaust gas regulations and environmental regulations, there has been an increasing need to use an electric power unit equipped with a battery that can replace a general-purpose engine as a drive source for working machines. The electric power unit is preferably capable of being mounted on various types of working machines, and there is a demand for downsizing and improved versatility. In addition, in order to enhance the stability of a working machine equipped with an electric power unit, it is required to lower the center of gravity of the electric power unit and bring it closer to the wheel axle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 discloses an electric power unit in which a battery is disposed directly above a motor via a frame that surrounds the upper and side portions of the motor in order to improve the downsizing of the electric power unit. In such an electric power unit, the center of gravity of the electric power unit becomes high, and there is a possibility that it may be difficult to ensure the stability of a working machine equipped with the electric power unit.

[0005] In view of the circumstances described above, at least one embodiment of this disclosure aims to provide an electric power unit that can lower its center of gravity and improve stability by bringing it closer to the wheel axle of the work machine, and a work machine equipped with the electric power unit. [Means for solving the problem]

[0006] An electric power unit according to at least one embodiment of the present disclosure is An electric power unit comprising a motor device having a rotating shaft, a controller for controlling the operation of the motor device, and a battery device for driving the motor device, The battery device is positioned so as to cover the upper part of the motor device and the upper part of one side of the motor device when viewed from the axial direction of the rotating shaft, and is detachably supported by the motor device.

[0007] A work machine according to at least one embodiment of this disclosure is It is equipped with the aforementioned electric power unit. [Effects of the Invention]

[0008] According to at least one embodiment of the present disclosure, an electric power unit is provided that can lower its center of gravity and improve stability by bringing it closer to the wheel axle of the work machine, and a work machine equipped with the electric power unit is provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic front view of a work machine equipped with an electric power unit according to one embodiment of the present disclosure, viewed from the axial direction of the rotating shaft. [Figure 2] This is a schematic front view of a work machine equipped with an engine unit instead of an electric power unit according to one embodiment of the present disclosure, viewed from the axial direction of the rotating shaft. [Figure 3] Figure 2 is a schematic front view of the engine unit as seen from the axial direction of the rotation axis. [Figure 4]Figure 1 is a schematic front view of the electric power unit as seen from the axial direction of the rotating shaft. [Figure 5] This is a schematic perspective view of a motor device in one embodiment of the present disclosure. [Figure 6] This is an explanatory diagram illustrating the attachment of a battery device to a motor device in one embodiment of the present disclosure. [Figure 7] This is a schematic perspective view of a secondary battery cell of a battery pack in one embodiment of the present disclosure. [Figure 8] This is a schematic diagram of a battery pack in one embodiment of the present disclosure, viewed from the axial direction of the secondary battery cells. [Figure 9] This is an explanatory diagram illustrating a plurality of tab terminals in one embodiment of the present disclosure. [Figure 10] This is an explanatory diagram illustrating a plurality of tab terminals in one embodiment of the present disclosure. [Figure 11] This is a schematic perspective view of a battery device in one embodiment of the present disclosure. [Modes for carrying out the invention]

[0010] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of this disclosure, but are merely illustrative examples.

[0011] (Work equipment) Figure 1 is a schematic front view of a work implement 10 equipped with an electric power unit 1 according to one embodiment of the present disclosure, viewed from the axial direction of the rotation axis RA1 of the electric power unit 1. Figure 2 is a schematic front view of a work implement 10 equipped with an engine unit 100 instead of the electric power unit 1 according to one embodiment of the present disclosure, viewed from the axial direction of the rotation axis RA2 of the engine unit 100. Examples of work implements 10 include tillers, cultivators, lawnmowers, snowplows, etc., for managing soil. The following explanation will use a tiller as an example.

[0012] As shown in FIGS. 1 and 2, the working machine 10 is equipped with an electric power unit 1 or an engine unit 100 as a drive source. Hereinafter, when viewed from one side in the axial direction of the rotary shafts RA1 and RA2, one side in the horizontal direction (the left side in FIGS. 1 and 2) is defined as the first side S1, and the other side in the horizontal direction (the right side in FIGS. 1 and 2) is defined as the second side S2.

[0013] As shown in FIGS. 1 and 2, the working machine 10 includes a working machine main body 11 having a mounting portion 12 for mounting the electric power unit 1 or the engine unit 100, a wheel 13 rotatably supported by the working machine main body 11 and configured to be rotatable about the wheel axle WA of the working machine 10, a rotary blade 14 rotatably supported by the working machine main body 11, and a handle 15. For example, when an operator holding the handle 15 pushes the working machine 10 toward the second side S2 which is in the front, the wheel 13 rotates and the working machine 10 moves forward. The working machine (management machine) 10 performs management operations such as plowing, digging, weeding, and ridge forming by the rotary blade 14 that rotates with the electric power unit 1 or the engine unit 100 as a drive source.

[0014] In the embodiment shown in FIGS. 1 and 2, the wheel 13 is disposed on the one side (the first side S1) above the rotary shafts RA1 and RA2, and the rotary blade 14 is disposed on the one side above the wheel 13. The wheel axle WA is also located on the one side (the first side S1) above the rotary shafts RA1 and RA2. Further, the handle 15 is disposed such that the upper end side is inclined toward the one side more than the lower end side, and the lower end is fixed to the working machine main body 11 on the one side above the rotary shafts RA1 and RA2. And the wheel 13 is disposed at a position where at least a part thereof overlaps with the electric power unit 1 or the engine unit 100 in the horizontal direction when viewed from one side in the axial direction of the rotary shafts RA1 and RA2.

[0015] The electric power unit 1 is alternatively mounted on the work machine 10 in place of the engine unit 100. Therefore, the electric power unit 1 requires mounting compatibility equivalent to that of the engine unit 100. The mounting portion 12 of the work machine 10 may be mounted with the electric power unit 1 or the engine unit 100. The electric power unit 1 and the engine unit 100 are detachably placed on the mounting portion 12 via fastening members (not shown).

[0016] (Engine unit) FIG. 3 is a schematic front view of the engine unit 100 shown in FIG. 2 as viewed from the axial direction of the rotation axis RA2. As shown in FIG. 3, the engine unit 100 includes an engine 101 including a cylinder 102 and a piston 103 disposed inside the cylinder 102, a fuel tank 104 disposed directly above the engine 101, and a base 105 fixed below the engine 101.

[0017] When the cylinder 102 is viewed from the axial direction of the rotation axis RA2 as shown in FIG. 3, the upper end side is inclined toward the one side (the first side S1) more than the lower end side. Thereby, the center of gravity C2 of the engine unit 100 is located above the rotation axis RA2 and on the one side of the rotation axis RA2. The engine 101 is configured such that a clearance space CS2 is formed below the one side (the first side S1).

[0018] Fuel for the engine 101 is stored in the fuel tank 104. The engine unit 100 is fixed to the work machine 10 by placing the base 105 on the mounting portion 12 and fastening it to the mounting portion 12 via fastening members (not shown).

[0019] (Electric power unit) Figure 4 is a schematic front view of the electric power unit 1 shown in Figure 1, viewed from the axial direction of the rotation axis RA1. As shown in Figure 4, the electric power unit 1 comprises a motor device 2 having a rotation axis RA1, a controller 3 for controlling the operation of the motor device 2, and a battery device 4 for driving the motor device 2.

[0020] (Motor device) The motor device 2 includes a motor rotor 21 that can rotate around a rotation axis RA1 as its center of rotation, a motor stator 22 that faces the motor rotor 21 with a gap between them, a motor casing 23 that houses the motor rotor 21 and the motor stator 22, and a base 24 fixed below the motor casing 23. The motor casing 23 is designed to rotatably house the motor rotor 21 by supporting a bearing (not shown) that rotatably supports the motor rotor 21 inside.

[0021] The motor rotor 21 includes permanent magnets, and the motor stator 22 includes coils. The motor device 2 is electrically and mechanically connected to the controller 3 and the battery device 4. The motor device 2 rotates the motor rotor 21 using power supplied from the battery device 4 in response to instructions (instruction signals) sent from the controller 3. The motor device 2 may also be configured to increase or decrease the rotational speed of the motor rotor 21 in response to instructions (instruction signals) regarding rotational speed sent from the controller 3.

[0022] The electric power unit 1 is fixed to the work machine 10 by having its base 24 placed on the mounting section 12 and fastened to the mounting section 12 via fastening members (not shown).

[0023] (controller) The controller 3 is electrically and mechanically connected to the battery device 4 and operates using power supplied from the battery device 4. In the illustrated embodiment, the controller 3 includes a control circuit 31 for controlling the motor device 2.

[0024] (Battery device) The battery device 4 includes a battery pack 41 that serves as a power source for the electric power unit 1, and a battery casing 42 that houses the battery pack 41. As shown in Figure 4, the battery casing 42 of the battery device 4 is positioned to cover the upper part of the motor device 2 and the upper part of the side of one side (first side S1) of the motor device 2 when viewed from the axial direction of the rotation axis RA1, and is detachably supported by the motor device 2.

[0025] According to the above configuration, by positioning the battery device 4 to cover the upper part of the motor device 2 and the upper part of one side, the volume of the battery (battery pack 41) that can be housed in the battery device 4 can be increased, thus ensuring sufficient battery capacity. Furthermore, by positioning the battery device 4 to cover the upper part of the motor device 2 and the upper part of one side, the center of gravity C1 of the electric power unit 1 can be lowered and brought closer to the wheel axle WA of the work machine 10 compared to the case where the battery device 4 is positioned to cover only the upper part of the motor device 2, thereby improving the stability of the electric power unit 1.

[0026] As shown in Figure 4, the center of gravity C1 of the electric power unit 1 is located above the rotation axis RA1 and on one side of the rotation axis RA1, similar to the center of gravity C2 of the engine unit 100. The electric power unit 1 has a gap space CS1 formed below the one side (first side S1), specifically below the lower end portion 43 of the battery casing 42 on that side. The electric power unit 1 can be suitably replaced by the engine unit 100 because it has a gap space CS1 similar to the gap space CS2 of the engine unit 100. Components of the work machine 10, such as the handle 15, may be placed in the gap spaces CS1 and CS2, and in this case, the electric power unit 1, which does not have a gap space CS1, may be difficult to mount on the work machine 10.

[0027] In some embodiments, as shown in Figure 4, when the circumferential angle θ is defined as 0° being the circumferential position vertically above the rotation axis RA1 in a plane perpendicular to the rotation axis RA1, and the direction toward the first side S1 from the 0° position being the positive direction, the battery casing 42 of the battery device 4 is located at least within the circumferential range from the 0° position to the 90° position. The other end 45 of the battery casing 42 (second side S2) may be located within the circumferential range from the 330° position to the 360° position, and the lower end 43 of the one side (first side S1) of the battery casing 42 may be located within the circumferential range from the 90° position to the 120° position.

[0028] The battery casing 42 of the battery device 4 includes a lateral covering portion 42A (see Figure 6), which covers the upper part of one side of the motor device 2, and an upper covering portion 42B (see Figure 6), which covers the top of the motor device 2. The boundary between the lateral covering portion 42A and the upper covering portion 42B may be defined at a 45° circumferential position.

[0029] In some embodiments, as shown in Figure 4, the controller 3 described above is positioned to the other side (second side S2) of the motor device 2 when viewed from the axial direction of the rotation axis RA1, and is supported by the motor device 2.

[0030] According to the above configuration, by positioning the controller 3 on the opposite side of the motor unit 2 where the battery unit 4 is located, the bias of the center of gravity C1 of the electric power unit 1 to that side can be suppressed. This suppresses the weight balance bias of the electric power unit 1, thereby improving the stability of the electric power unit 1.

[0031] (Support structure for battery device) Figure 5 is a schematic perspective view of a motor device 2 in one embodiment of the present disclosure. Figure 6 is an explanatory diagram illustrating the attachment of a battery device 4 to the motor device 2 in one embodiment of the present disclosure.

[0032] In some embodiments, the motor device 2 described above includes a first support member 5 and a second support member 6, as shown in Figures 5 and 6. The first support member 5 extends along a direction parallel to the rotation axis RA1 and is configured to detachably support one lower end 43 of the battery device 4. The second support member 6 extends along a direction parallel to the rotation axis RA1 and is configured to detachably support the other end 45 of the battery device 4. In the illustrated embodiments, the first support member 5 and the second support member 6 are formed in a rod shape extending along a direction parallel to the rotation axis RA1 and have a circular outer contour shape.

[0033] According to the above configuration, the battery device 4 can be detachably supported on the motor device 2 via the first support member 5 and the second support member 6. By simplifying the support structure of the battery device 4 in the electric power unit 1 in this way, the complexity of the structure of the electric power unit 1 can be suppressed, and the increase in weight and manufacturing costs that would result from such structural complexity can also be suppressed.

[0034] In some embodiments, the battery device 4 described above has, as shown in Figure 6, a first locking groove 44 formed at one lower end 43 of the battery device 4, into which the first support member 5 is locked, and a second locking groove 46 formed at the other end 45 of the battery device 4, into which the second support member 6 is locked. The first support member 5 is locked in the first locking groove 44 when its outer peripheral surface 51 abuts against the bottom surface of the first locking groove 44. The second support member 6 is locked in the second locking groove 46 when its outer peripheral surface 61 abuts against the bottom surface of the second locking groove 46.

[0035] As shown in Figure 6, the second locking groove 46 is configured such that, with the first support member 5 locked in the first locking groove 44, the second support member 6 can be inserted by rotating the battery device 4 in a direction that brings the second locking groove 46 closer to the second support member 6 (clockwise in Figure 6). The second locking groove 46 opens along the circumferential direction around the center RC1 of the first support member 5 when viewed from the axial direction of the rotation axis RA1.

[0036] With the above configuration, the battery device 4 can be attached to the motor device 2 by locking the first support member 5 into the first locking groove 44 and the second support member 6 into the second locking groove 46. By simplifying the attachment and detachment structure of the battery device 4 in the electric power unit 1 in this way, the complexity of the structure of the electric power unit 1 can be suppressed, and the increase in weight and manufacturing costs that would result from such structural complexity can also be suppressed. Furthermore, by simplifying the attachment and detachment structure of the battery device 4 in the electric power unit 1, the battery device 4 can be easily replaced.

[0037] (Engaging member) In some embodiments of the electric power unit 1, as shown in Figure 6, an engaging member (hook) 9 is further provided. The engaging member 9 is configured to be rotatable about an engaging member-side rotation axis RC2 that extends in a direction parallel to the rotation axis RA1. The engaging member 9 is configured to engage with the other end 45 of the battery device 4 when the second support member 6 is locked in the second locking groove 46.

[0038] In the illustrated embodiment, the engaging member 9 biases the other end 45 of the battery device 4 toward the other end when the second support member 6 is locked in the second locking groove 46. The reference numeral F in Figure 6 indicates the biasing force acting on the battery device 4 from the engaging member 9. The battery device 4 is biased by the engaging member 9 in a direction intersecting the direction in which the second support member 6 is inserted into the second locking groove 46 when viewed from the axial direction of the rotation axis RA1, thereby preventing the second locking groove 46 from separating from the second support member 6. In other words, the engaging member 9 fixes the battery device 4 to the motor device 2.

[0039] In the embodiment shown in Figure 6, the engaging member 9 has a first end portion 91 extending in a first direction relative to the engaging member-side rotating shaft RC2 when viewed from the axial direction of the rotating shaft RA1, and a second end portion 92 extending in a second direction different from the first direction relative to the engaging member-side rotating shaft RC2. The first end portion 91 has a first contact surface 911 that abuts against the other end face 423 of the battery casing 42 when the second support member 6 is locked in the second locking groove 46, and does not abut against the end face 423 when the second support member 6 is not locked in the second locking groove 46. The second end portion 92 has a second contact surface 921 that abuts against the bottom face 422 of the upper covering portion 42B of the battery casing 42 when the second support member 6 is locked in the second locking groove 46, and does not abut against the bottom face 422 when the second support member 6 is not locked in the second locking groove 46.

[0040] In the embodiment shown in Figure 6, when the second support member 6 is locked into the second locking groove 46, the bottom surface 422 of the battery casing 42 comes into contact with the second contact surface 921, biasing the end surface 423 toward one side. This causes the engaging member 9 to rotate counterclockwise in Figure 6 around the engaging member side rotation axis RC2, causing the first contact surface 911 to come into contact with the end surface 423, biasing the end surface 423 toward one side. The engaging member 9 is not limited to the embodiment shown in Figure 6, and only needs to be configured to engage with the other end 45 of the battery device 4 when the second support member 6 is locked into the second locking groove 46.

[0041] According to the above configuration, when the second support member 6 is locked in the second locking groove 46, the engaging member 9 can be engaged with the other end 45 of the battery device 4, thereby fixing the battery device 4 to the motor device 2. By making the fixing of the battery device 4 to the motor device 2 in the electric power unit 1 a simple structure, the installation work of the battery device 4 can be simplified.

[0042] In some embodiments, as shown in Figure 5, the motor device 2 described above includes a first support portion 25 that faces a first end face 52, which is one end face of the first support member 5 in the extending direction, via a first gap G1. The first support portion 25 supports one side of the first support member 5 via a first elastic member 71 positioned in the first gap G1. One end of the first elastic member 71 abuts against the first end face 52, and the other end abuts against the first support portion 25 facing the first end face 52.

[0043] The motor device 2 described above includes a second support portion 26 that faces the second end face 53, which is the other end face of the first support member 5 in the extending direction, via a second gap G2. The second support portion 26 supports the other side of the first support member 5 via a second elastic member 72 positioned in the second gap G2. One end of the second elastic member 72 abuts against the second end face 53, and the other end abuts against the second support portion 26 facing the second end face 53. In the illustrated embodiment, the first support portion 25 and the second support portion 26 are integrally formed with the motor casing 23 and protrude radially outward from the motor casing 23.

[0044] According to the above configuration, by a simple structure in which both ends of the first support member 5 are supported by the first support portion 25 and the second support portion 26 of the motor device 2 via the first elastic member 71 and the second elastic member 72, vibration transmission from the motor device 2 to the battery device 4 via the first support member 5 can be suppressed, thereby protecting the battery device 4 from vibrations of the motor device 2.

[0045] In some embodiments, as shown in Figure 5, the motor device 2 described above includes a third support portion 27 that faces a third end face 62, which is one end face of the second support member 6 in the extending direction, via a third gap G3. The third support portion 27 supports one side of the second support member 6 via a third elastic member 73 positioned in the third gap G3. One end of the third elastic member 73 abuts against the third end face 62, and the other end abuts against the third support portion 27 facing the third end face 62.

[0046] The motor device 2 described above includes a fourth support portion 28 that faces the fourth end face 63, which is the other end face of the second support member 6 in the extending direction, via a fourth gap G4. The fourth support portion 28 supports the other side of the second support member 6 via a fourth elastic member 74 positioned in the fourth gap G4. One end of the fourth elastic member 74 abuts against the fourth end face 63, and the other end abuts against the fourth support portion 28 facing the fourth end face 63. In the illustrated embodiment, the third support portion 27 and the fourth support portion 28 are integrally formed with the motor casing 23 and protrude radially outward from the motor casing 23.

[0047] According to the above configuration, a simple structure is used in which both ends of the second support member 6 are supported by the third support portion 27 and the fourth support portion 28 of the motor device 2 via the third elastic member 73 and the fourth elastic member 74. This suppresses the transmission of vibrations from the motor device 2 to the battery device 4 via the second support member 6, thus protecting the battery device 4 from vibrations of the motor device 2. Since the battery device 4 is supported by the motor device 2 via the first support member 5 and the second support member 6, suppressing the transmission of vibrations from the motor device 2 via the first support member 5 and the second support member 6 effectively protects the battery device 4 from vibrations of the motor device 2.

[0048] In some embodiments, as shown in Figure 6, the battery device 4 described above has a battery-side electrical connection port 47 provided in the upper covering portion 42B of the battery device 4 that covers the motor device 2 when viewed from the axial direction of the rotating shaft RA1. In the illustrated embodiment, the battery-side electrical connection port 47 is provided on the bottom surface 422 of the upper covering portion 42B.

[0049] As shown in Figure 6, the battery-side electrical connection port 47 is configured to connect to the controller-side electrical connection port 32 of the controller 3 when the second support member 6 is locked in the second locking groove 46.

[0050] According to the above configuration, when the second support member 6 is locked into the second locking groove 46, the battery-side electrical connection port 47 is connected to the controller-side electrical connection port 32, thereby electrically connecting the battery device 4 to the controller 3. In this case, there is no need to perform a separate electrical connection operation for the battery device 4 to the controller 3, thus simplifying the installation of the battery device 4.

[0051] (Battery pack structure) Figure 7 is a schematic perspective view of a secondary battery cell 40 of a battery pack 41 in one embodiment of the present disclosure. Figure 8 is a schematic view of a battery pack 41 in one embodiment of the present disclosure, viewed from the axial direction of the secondary battery cell 40. In some embodiments, the battery pack 41 described above is composed of a plurality of cylindrical secondary battery cells 40, each extending along a direction parallel to the rotation axis RA1, as shown in Figures 7 and 8. In other words, the battery device 4 includes a plurality of secondary battery cells 40. Examples of secondary battery cells 40 suitably used in the electric power unit 1 include lithium-ion battery cells.

[0052] Each of the multiple secondary battery cells 40, although not shown, includes an electron-emitting electrode (anode, positive electrode), an electron-receiving electrode (cathode, negative electrode), and an electrolyte membrane sandwiched between the electron-emitting electrode and the electron-receiving electrode so as to separate them. Each of the multiple secondary battery cells 40 is provided with an electron-emitting electrode terminal 401 on one end face in the extending direction of the secondary battery cell 40, and an electron-receiving electrode 402 on the other end face in the extending direction of the secondary battery cell 40.

[0053] By arranging multiple secondary battery cells 40 in a cylindrical shape that extends along a direction parallel to the rotation axis RA1, the multiple secondary battery cells 40 can be space-efficiently arranged inside the battery device 4, which is positioned to cover the upper part of the motor device 2 and the upper part of one of its sides. The battery device 4 can secure sufficient battery capacity by space-efficiently arranging the multiple secondary battery cells 40 inside the battery device 4.

[0054] In some embodiments, the plurality of secondary battery cells 40 described above are arranged vertically (up and down in the figure) when viewed from the axial direction of the rotation axis RA1 as shown in Figure 8, and include a plurality of secondary battery cells 40 constituting a first battery cell group 40A. Furthermore, the plurality of secondary battery cells 40 are arranged on the other side (second side S2) of the motor device 2 relative to the uppermost secondary battery cell 40 of the first battery cell group 40A when viewed from the axial direction of the rotation axis RA1 as shown in Figure 8, and include a plurality of secondary battery cells 40 constituting a second battery cell group 40B.

[0055] Multiple secondary battery cells 40 belonging to the first battery cell group 40A are arranged in positions that overlap each other when viewed from above. Multiple secondary battery cells 40 belonging to the second battery cell group 40B are arranged in positions that are offset from each other in the horizontal direction from the first side S1 to the second side S2 when viewed from above.

[0056] With the above configuration, multiple secondary battery cells 40 constituting the first battery cell group 40A can be arranged inside the lateral covering portion 42A (see Figure 6), which is the portion that covers the upper side of one side of the motor device 2 in the battery device 4, and multiple secondary battery cells 40 constituting the second battery cell group 40B can be arranged inside the upper covering portion 42B (see Figure 6), which is the portion that covers the top of the motor device 2 in the battery device 4. In this case, multiple secondary battery cells 40 can be arranged inside the lateral covering portion 42A and the upper covering portion 42B in a space-efficient manner.

[0057] In some embodiments, the multiple secondary battery cells 40 constituting the second battery cell group 40B described above are arranged to be shifted upward as they move toward the other side (second side S2) of the motor device 2 when viewed from the axial direction of the rotation axis RA1, as shown in Figure 8. When viewed from the axial direction of the rotation axis RA1, the direction of arrangement of the multiple secondary battery cells 40 belonging to the second battery cell group 40B intersects at an obtuse angle with the vertical direction, which is the direction of arrangement of the multiple secondary battery cells 40 belonging to the first battery cell group 40A.

[0058] According to the above configuration, the multiple secondary battery cells 40 constituting the second battery cell group 40B, which is located on one side (first side S1) to match the upper shape of the motor device 2, can be positioned as low as possible, thereby lowering the center of gravity C1 of the electric power unit 1. In some other embodiments, the arrangement direction of the multiple secondary battery cells 40 belonging to the second battery cell group 40B may be along the horizontal direction.

[0059] In some embodiments, the above-described plurality of secondary battery cells 40 further include a plurality of secondary battery cells 40 that constitute a third battery cell group 40C stacked on one side (first side S1) of the motor device 2, relative to the plurality of secondary battery cells 40 that constitute a first battery cell group 40A when viewed from the axial direction of the rotation axis RA1 as shown in Figure 8. Furthermore, the above-described plurality of secondary battery cells 40 further include a plurality of secondary battery cells 40 that constitute a fourth battery cell group 40D stacked above the plurality of secondary battery cells 40 that constitute a second battery cell group 40B when viewed from the axial direction of the rotation axis RA1 as shown in Figure 8.

[0060] As shown in Figure 8, the multiple secondary battery cells 40 constituting the third battery cell group 40C are stacked in one or more layers (two layers in the illustrated example) along a direction perpendicular to the direction in which the multiple secondary battery cells 40 belonging to the first battery cell group 40A are arranged, when viewed from the axial direction of the rotation axis RA1. The multiple secondary battery cells 40 belonging to each layer of the third battery cell group 40C are positioned to overlap each other when viewed from above.

[0061] As shown in Figure 8, the multiple secondary battery cells 40 constituting the fourth battery cell group 40D are stacked in one or more layers (two layers in the illustrated example) along a direction perpendicular to the direction in which the multiple secondary battery cells 40 belonging to the second battery cell group 40B are arranged, when viewed from the axial direction of the rotation axis RA1. The multiple secondary battery cells 40 belonging to each layer of the fourth battery cell group 40D are positioned offset from each other in the horizontal direction from the first side S1 to the second side S2 when viewed from above.

[0062] In the embodiment shown in Figure 8, the multiple secondary battery cells 40 constituting each layer of the fourth battery cell group 40D are arranged to be shifted upward as they move toward the other side (second side S2) of the motor device 2 when viewed from the axial direction of the rotation axis RA1. In some other embodiments, the arrangement direction of the multiple secondary battery cells 40 constituting each layer of the fourth battery cell group 40D may be along the horizontal direction.

[0063] According to the above configuration, by stacking the secondary battery cells 40 belonging to the third battery cell group 40C on the secondary battery cells 40 belonging to the first battery cell group 40A, and stacking the secondary battery cells 40 belonging to the fourth battery cell group 40D on the secondary battery cells 40 belonging to the second battery cell group 40B, the battery capacity of the electric power unit 1 can be increased while suppressing an increase in the center of gravity C1 of the electric power unit 1.

[0064] In some embodiments, as shown in Figures 7 and 8, the above-described plurality of secondary battery cells 40 may be arranged in series in the direction of extension of the secondary battery cells 40.

[0065] (Tab terminals) Figure 9 is an explanatory diagram illustrating a plurality of tab terminals 48 (48A to 48C) in one embodiment of the present disclosure. Figure 10 is an explanatory diagram illustrating a plurality of tab terminals 48 (48D to 48G) in one embodiment of the present disclosure. In some embodiments, the battery device 4 described above further includes a plurality of tab terminals 48 (48A to 48G) that are electrically and mechanically connected to two or more secondary battery cells 40 among a plurality of secondary battery cells 40, as shown in Figures 9 and 10.

[0066] The plurality of tab terminals 48 include a first tab terminal 481 and a second tab terminal 482 connected to a plurality of secondary battery cells 40 having the same arrangement as the plurality of secondary battery cells 40 connected to the first tab terminal 481. Each of the first tab terminal 481 and the second tab terminal 482 may be connected to the electron-emitting side electrode terminal 401 of each of the plurality of secondary battery cells 40, or to the electron-receiving side electrode 402 of each of the plurality of secondary battery cells 40.

[0067] Each of the multiple tab terminals 48A to 48C is connected to the electron-receiving electrode 402, as shown in Figure 9. Each of the multiple tab terminals 48D to 48G is connected to the electron-emitting electrode terminal 401, as shown in Figure 10. In the embodiments shown in Figures 9 and 10, when tab terminal 48C is designated as the first tab terminal 481, tab terminals 48A and 48F correspond to the second tab terminal 482. Also, when tab terminal 48B is designated as the first tab terminal 481, tab terminal 48D corresponds to the second tab terminal 482. It is preferable that the second tab terminal 482 has the same shape as the first tab terminal 481.

[0068] According to the above configuration, the number of types of tab terminals 48 connected to the battery pack 41 can be reduced. Reducing the number of types of tab terminals 48 makes it easier to manage the components that make up the battery device 4.

[0069] (Battery level indicator) Figure 11 is a schematic perspective view of a battery device 4 in one embodiment of the present disclosure. In some embodiments, the electric power unit 1 described above further comprises a battery level indicator 8 for indicating the remaining battery level of the battery device 4, as shown in Figure 11. The battery level indicator 8 is provided on the upper surface 421 of the battery casing 42 described above. The battery level indicator 8 is electrically connected to the battery pack 41 and is capable of visually displaying the remaining battery level of the battery pack 41.

[0070] According to the above configuration, by providing the battery level indicator 8 on the upper surface 421 of the battery device 4, users of equipment equipped with the electric power unit 1 can directly see the battery level indicator 8 while using the equipment.

[0071] As shown in Figure 1, some embodiments of the work machine 10 include the electric power unit 1 described above. In this case, the center of gravity C1 of the electric power unit 1 can be lowered, and the stability of the work machine 10 equipped with the electric power unit 1 can be improved.

[0072] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. Furthermore, in this specification, expressions describing shapes such as quadrilaterals and cylindrical shapes shall not only represent geometrically precise quadrilaterals and cylindrical shapes, but also shapes that include uneven surfaces, chamfered surfaces, etc., to the extent that the same effect can be achieved. Furthermore, in this specification, the expressions “equipment,” “includes,” or “possess” of a component are not exclusive expressions that exclude the existence of other components.

[0073] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0074] The contents described in some of the embodiments above can be understood, for example, as follows:

[0075] 1) An electric power unit (1) according to at least one embodiment of the present disclosure is An electric power unit (1) comprising a motor device (2) having a rotating shaft (RA1), a controller (3) for controlling the operation of the motor device (2), and a battery device (4) for driving the motor device (2), The battery device (4) is positioned to cover the upper part of the motor device (2) and the upper part of one side of the motor device (2) when viewed from the axial direction of the rotating shaft (RA1), and is detachably supported by the motor device (2).

[0076] According to the configuration in 1) above, by arranging the battery device (4) to cover the upper part of the motor device (2) and the upper part of one side, the volume of the battery that can be housed in the battery device (4) can be increased, thus ensuring sufficient battery capacity. Furthermore, by arranging the battery device (4) to cover the upper part of the motor device (2) and the upper part of one side, the center of gravity (C1) of the electric power unit (1) can be lowered and brought closer to the wheel axle (WA) of the work machine (10), thereby improving the stability of the electric power unit (1).

[0077] 2) In some embodiments, the electric power unit (1) described in 1) above, The motor device (2) is A first support member (5) extends along a direction parallel to the rotation axis (RA1) and detachably supports the lower end (43) on one side of the battery device (4), The system includes a second support member (6) that extends along a direction parallel to the rotation axis (RA1) and detachably supports the other end (45) of the battery device (4).

[0078] According to the configuration described in 2) above, the battery device (4) can be detachably supported on the motor device (2) via the first support member (5) and the second support member (6). By simplifying the support structure of the battery device (4) in the electric power unit (1) in this way, the complexity of the structure of the electric power unit (1) can be suppressed, and the increase in weight and manufacturing costs that would result from such structural complexity can also be suppressed.

[0079] 3) In some embodiments, the electric power unit (1) described in 2) above, The aforementioned battery device (4) A first locking groove (44) is formed on the lower end (43) of one side of the battery device (4) and the first support member (5) is locked into it, The battery device (4) has a second locking groove (46) formed at the other end (45) where the second support member (6) is locked, The second locking groove (46) is configured such that the second support member (6) is inserted when the battery device (4) is rotated while the first support member (5) is locked in the first locking groove (44).

[0080] According to the configuration described in 3) above, the battery device (4) can be attached to the motor device (2) by locking the first support member (5) into the first locking groove (44) and the second support member (6) into the second locking groove (46). By simplifying the attachment and detachment structure of the battery device (4) in the electric power unit (1) in this way, the complexity of the structure of the electric power unit (1) can be suppressed, and the increase in weight and manufacturing costs that would result from such structural complexity can also be suppressed. Furthermore, by simplifying the attachment and detachment structure of the battery device (4) in the electric power unit (1), the battery device (4) can be easily replaced.

[0081] 4) In some embodiments, the electric power unit (1) described in 3) above, The engaging member (9) is configured to be rotatable about an engaging member-side rotating shaft (RC2) that extends in a direction parallel to the rotating shaft (RA1), and further comprises an engaging member (9) configured to engage with the other end (45) of the battery device (4) when the second support member (6) is locked in the second locking groove (46).

[0082] According to the configuration described in 4) above, when the second support member (6) is locked in the second locking groove (46), the engaging member (9) can be engaged with the other end (45) of the battery device (4), thereby fixing the battery device (4) to the motor device (2). By making the fixing of the battery device (4) to the motor device (2) in the electric power unit (1) a simple structure, the installation work of the battery device (4) can be simplified.

[0083] 5) In some embodiments, the electric power unit (1) described in any of 2) to 4) above, The motor device (2) is A first support portion (25) that faces the first end face (52), which is one end face in the extending direction of the first support member (5), via a first gap (G1), and the first support portion (25) that supports the one side of the first support member (5) via a first elastic member (71) disposed in the first gap (G1), The present invention further includes a second support portion (26) that faces the second end face (53), which is the other end face of the first support member (5) in the extending direction, via a second gap (G2), and the second support portion (26) supports the other side of the first support member (5) via a second elastic member (72) disposed in the second gap (G2).

[0084] According to the configuration in 5) above, the first support member (5) is supported at both ends by the first support portion (25) and the second support portion (26) of the motor device (2) via the first elastic member (71) and the second elastic member (72). This simple structure suppresses the transmission of vibrations from the motor device (2) to the battery device (4) via the first support member (5), thus protecting the battery device (4) from vibrations of the motor device (2).

[0085] 6) In some embodiments, the electric power unit (1) described in 5) above, The motor device (2) is A third support portion (27) that faces the third end face (62), which is one end face in the extending direction of the second support member (6), via a third gap (G3), and the third support portion (27) supports the one side of the second support member (6) via a third elastic member (73) disposed in the third gap (G3), The present invention further includes a fourth support portion (28) that faces the fourth end face (63), which is the other end face of the second support member (6) in the extending direction, via a fourth gap (G4), and the fourth support portion (28) supports the other side of the second support member (6) via a fourth elastic member (74) disposed in the fourth gap (G4).

[0086] According to the configuration in 6) above, the transmission of vibrations from the motor device (2) to the battery device (4) via the second support member (6) can be suppressed by a simple structure in which both ends of the second support member (6) are supported by the third support part (27) and the fourth support part (28) of the motor device (2) via the third elastic member (73) and the fourth elastic member (74), thereby protecting the battery device (4) from vibrations of the motor device (2). Since the battery device (4) is supported by the motor device (2) via the first support member (5) and the second support member (6), the transmission of vibrations from the motor device (2) via the first support member (5) and the second support member (6) can be suppressed, thereby effectively protecting the battery device (4) from vibrations of the motor device (2).

[0087] 7) In some embodiments, the electric power unit (1) described in 3) or 4) above, The aforementioned battery device (4) When viewed from the axial direction of the rotating shaft (RA1), the battery device (4) has an electrical connection port (47) on the battery side, which is provided in the upper covering portion (42B) of the battery device (4) that covers the upper part of the motor device (2), The battery-side electrical connection port (47) is configured to connect to the controller-side electrical connection port (32) of the controller (3) when the second support member (6) is locked into the second locking groove (46).

[0088] According to the configuration described in 7) above, when the second support member (6) is locked into the second locking groove (46), the battery-side electrical connection port (47) is connected to the controller-side electrical connection port (32), thereby electrically connecting the battery device (4) to the controller (3). In this case, it is not necessary to perform a separate operation to electrically connect the battery device (4) to the controller (3), thus simplifying the installation of the battery device (4).

[0089] 8) In some embodiments, the electric power unit (1) described in any of 1) to 7) above, The controller (3) is positioned on the other side of the motor device (2) when viewed from the axial direction of the rotating shaft (RA1), and is supported by the motor device (2).

[0090] According to the configuration described in 8) above, by positioning the controller (3) on the opposite side from the motor unit (2) where the battery unit (4) is located, the center of gravity (C1) of the electric power unit (1) can be suppressed from being biased to that side. This suppresses the weight balance imbalance of the electric power unit (1), thereby improving the stability of the electric power unit (1).

[0091] 9) In some embodiments, the electric power unit (1) described in any of 1) to 8) above, A battery level indicator (8) for indicating the remaining battery level of the battery device (4) is further provided, the battery level indicator (8) being located on the upper surface (421) of the battery device (4).

[0092] According to the configuration described in 9) above, by providing the battery level indicator (8) on the top surface (421) of the battery device (4), users of equipment equipped with the electric power unit (1) can directly see the battery level indicator (8) while using the equipment.

[0093] 10) In some embodiments, the electric power unit (1) described in any of 1) to 9) above, The aforementioned battery device (4) It includes a plurality of secondary battery cells (40) each formed in a cylindrical shape and extending along a direction parallel to the rotation axis (RA1).

[0094] According to the configuration described in 10) above, by making the multiple secondary battery cells (40) cylindrical in shape and extending along a direction parallel to the rotation axis (RA1), the multiple secondary battery cells (40) can be space-efficiently arranged inside the battery device (4) which is positioned to cover the upper part of the motor device (2) and the upper part of one side. The battery device (4) can secure sufficient battery capacity by space-efficiently arranging the multiple secondary battery cells (40) inside the battery device (4).

[0095] 11) In some embodiments, the electric power unit (1) described in 10) above, The aforementioned multiple secondary battery cells (40) are When viewed from the axial direction of the rotation axis (RA1), a plurality of secondary battery cells (40) are arranged vertically and constitute the first battery cell group (40A), The device includes a plurality of secondary battery cells (40) that constitute a second battery cell group (40B), arranged on the other side of the motor device (2) relative to the uppermost secondary battery cell (40) in the first battery cell group (40A) when viewed from the axial direction of the rotating shaft (RA1).

[0096] According to the configuration described in 11) above, multiple secondary battery cells (40) constituting the first battery cell group (40A) can be arranged inside the lateral covering portion (42A), which is the part that covers the upper part of one side of the motor device (2) in the battery device (4), and multiple secondary battery cells (40) constituting the second battery cell group (40B) can be arranged inside the upper covering portion (42B), which is the part that covers the top of the motor device (2) in the battery device (4). In this case, multiple secondary battery cells (40) can be arranged inside the lateral covering portion (42A) and the upper covering portion (42B) in a space-efficient manner.

[0097] 12) In some embodiments, the electric power unit (1) described in 11) above, The plurality of secondary battery cells (40) constituting the second battery cell group (40B) are arranged to be shifted upward as they move toward the other side of the motor device (2) when viewed from the axial direction of the rotation shaft (RA1).

[0098] According to the configuration described in 12) above, the multiple secondary battery cells (40) constituting the second battery cell group (40B) located on one side can be positioned as far down as possible to match the upper shape of the motor device (2), thereby lowering the center of gravity (C1) of the electric power unit (1).

[0099] 13) In some embodiments, the electric power unit (1) described in 11) or 12) above, The aforementioned multiple secondary battery cells (40) are When viewed from the axial direction of the rotating shaft (RA1), the plurality of secondary battery cells (40) that constitute the first battery cell group (40A) are stacked on one side of the motor device (2), and the plurality of secondary battery cells (40) that constitute the third battery cell group (40C) are stacked on the other side of the motor device (2). The present invention further includes a plurality of secondary battery cells (40) that constitute a fourth battery cell group (40D) which is stacked above the plurality of secondary battery cells (40) that constitute the second battery cell group (40B) when viewed from the axial direction of the rotation axis (RA1).

[0100] According to the configuration described in 13) above, by stacking the secondary battery cells (40) belonging to the third battery cell group (40C) on the secondary battery cells (40) belonging to the first battery cell group (40A), and stacking the secondary battery cells (40) belonging to the fourth battery cell group (40D) on the secondary battery cells (40) belonging to the second battery cell group (40B), the battery capacity of the electric power unit (1) can be increased while suppressing an increase in the center of gravity (C1) of the electric power unit (1).

[0101] 14) In some embodiments, the electric power unit (1) described in any of 10) to 13) above, The aforementioned battery device (4) The plurality of secondary battery cells (40) further includes a plurality of tab terminals (48) that are electrically and mechanically connected to two or more secondary battery cells (40), The plurality of tab terminals (48) include a first tab terminal (481) and a second tab terminal (482) connected to a plurality of secondary battery cells (40) that have the same arrangement as the plurality of secondary battery cells (40) connected to the first tab terminal (481).

[0102] According to the configuration described in 14) above, the number of types of tab terminals (48) can be reduced. Reducing the number of types of tab terminals (48) makes it easier to manage the components that make up the battery device (4).

[0103] 15) A work machine (10) according to at least one embodiment of the present disclosure is The system comprises an electric power unit (1) as described in any of items 1) to 13) above.

[0104] According to the configuration described in 15) above, the center of gravity (C1) of the electric power unit (1) can be lowered, and the stability of the work machine (10) equipped with the electric power unit (1) can be improved. [Explanation of Symbols]

[0105] 1 Electric Power Unit 2. Motor device 3 Controllers 4. Battery device 5. First support member 6. Second support member 8. Battery level indicator 9 Engaging Member 10 Work Machines 21 Motor Rotor 22 Motor Stator 23 Motor casing 24 Base 25 1st support part 26 Second support part 27 Third support part 28 4th support part 31 Control circuits 32 Controller-side electrical connection port 40 secondary battery cells 40A~40D battery cell group 41 Battery Packs 42 Battery casing 42A Side covering 42B Upper covering section 43 Lower end on one side 44. First locking groove 45 The other end 46 Second locking groove 47 Battery side electrical connection port 48, 481, 482, 48A~48G Tab terminals 51,61 Outer surface 52,53,62,63 End face 71-74 Elastic members

Claims

1. An electric power unit comprising a motor device having a rotating shaft, a controller for controlling the operation of the motor device, and a battery device for driving the motor device, The battery device has a battery casing that houses the battery device, When viewed from the axial direction of the rotation axis, and the position vertically above the rotation axis is defined as 0°, and the direction toward one side of the motor device is defined as the positive direction, the circumferential angle is defined as follows: The battery casing is positioned to cover the upper part of the motor device and the upper part of the upper side of the motor device, such that it is present in at least the circumferential range from the 0° position to the 90° position, and the lower end of one side of the casing is present in the circumferential range from the 90° position to the 120° position. Below the lower end of one side of the battery casing, a gap space is formed on the side of the motor device. The battery device is detachably supported by the motor device. Electric power unit.

2. The motor device is A first support member extends along a direction parallel to the rotation axis and detachably supports the lower end of one side of the battery device, It includes a second support member that extends along a direction parallel to the rotation axis and detachably supports the other end of the battery device, The electric power unit according to claim 1.

3. The aforementioned battery device A first locking groove is formed at the lower end of one side of the battery device, and the first support member is locked into it. The battery device has a second locking groove formed at the other end, into which the second support member is locked, The second locking groove is configured such that the second support member is inserted when the battery device is rotated while the first support member is locked in the first locking groove. The electric power unit according to claim 2.

4. An electric power unit comprising a motor device having a rotating shaft, a controller for controlling the operation of the motor device, and a battery device for driving the motor device, The battery device has a battery casing that houses the battery device, When viewed from the axial direction of the rotation axis, and the position vertically above the rotation axis is defined as 0°, and the direction toward one side of the motor device is defined as the positive direction, the circumferential angle is defined as follows: The battery casing is positioned to cover the upper part of the motor device and the upper part of the upper side of the motor device, such that it is present in at least the circumferential range from the 0° position to the 90° position, and the lower end of one side of the casing is present in the circumferential range from the 90° position to the 120° position. The battery device is detachably supported by the motor device, The motor device is A first support member extends along a direction parallel to the rotation axis and detachably supports the lower end of one side of the battery device, It includes a second support member that extends along a direction parallel to the rotation axis and detachably supports the other end of the battery device, The aforementioned battery device A first locking groove is formed at the lower end of one side of the battery device, and the first support member is locked into it. The battery device has a second locking groove formed at the other end, into which the second support member is locked, The second locking groove is configured such that the second support member is inserted when the battery device is rotated while the first support member is locked in the first locking groove. An engaging member configured to be rotatable about an engaging member-side rotating shaft extending in a direction parallel to the rotation axis, further comprising an engaging member configured to engage with the other end of the battery device when the second support member is locked in the second locking groove, Electric power unit.

5. An electric power unit comprising a motor device having a rotating shaft, a controller for controlling the operation of the motor device, and a battery device for driving the motor device, The battery device has a battery casing that houses the battery device, When viewed from the axial direction of the rotation axis, and the position vertically above the rotation axis is defined as 0°, and the direction toward one side of the motor device is defined as the positive direction, the circumferential angle is defined as follows: The battery casing is positioned to cover the upper part of the motor device and the upper part of the upper side of the motor device, such that it is present in at least the circumferential range from the 0° position to the 90° position, and the lower end of one side of the casing is present in the circumferential range from the 90° position to the 120° position. The battery device is detachably supported by the motor device, The motor device is A first support member extends along a direction parallel to the rotation axis and detachably supports the lower end of one side of the battery device, It includes a second support member that extends along a direction parallel to the rotation axis and detachably supports the other end of the battery device, A first support portion facing the first end face, which is one end face in the extending direction of the first support member, via a first gap, the first support portion supports the one side of the first support member via a first elastic member disposed in the first gap, A second support portion facing the second end face, which is the other end face of the first support member in the extending direction, via a second gap, further comprising a second elastic member disposed in the second gap, the second support portion supporting the other side of the first support member, Electric power unit.

6. The motor device is A third support portion facing the third end face, which is one end face in the extending direction of the second support member, via a third gap, the third support portion supports the one side of the second support member via a third elastic member disposed in the third gap, A fourth support portion facing the fourth end face, which is the other end face of the second support member in the extending direction, via a fourth gap, further comprising a fourth elastic member disposed in the fourth gap, the fourth support portion supporting the other side of the second support member, The electric power unit according to claim 5.

7. The aforementioned battery device When viewed from the axial direction of the rotating shaft, the battery device has an electrical connection port on the battery side, provided in the upper covering portion of the battery device that covers the upper part of the motor device. The second support member is configured such that when the second support member is locked in the second locking groove, the battery-side electrical connection port is connected to the controller-side electrical connection port of the controller. The electric power unit according to claim 3 or 4.

8. The controller is positioned to cover at least a portion of the other side of the motor device when viewed from the axial direction of the rotation shaft, and is supported by the motor device. An electric power unit according to any one of claims 1, 4, or 5.

9. A battery level indicator for showing the remaining battery level of the battery device, further comprising a battery level indicator provided on the upper surface of the battery device, An electric power unit according to any one of claims 1, 4, or 5.

10. The aforementioned battery device It includes a plurality of secondary battery cells, each formed in a cylindrical shape and extending along a direction parallel to the rotation axis, An electric power unit according to any one of claims 1, 4, or 5.

11. The aforementioned multiple secondary battery cells are When viewed from the axial direction of the rotation axis, a plurality of secondary battery cells are arranged vertically and constitute the first battery cell group, When viewed from the axial direction of the rotation axis, the second battery cell group includes a plurality of secondary battery cells arranged on the other side of the motor device relative to the uppermost secondary battery cell in the first battery cell group, and which constitute the second battery cell group. The electric power unit according to claim 10.

12. The plurality of secondary battery cells constituting the second battery cell group are arranged so that, when viewed from the axial direction of the rotation shaft, they are shifted upward as they move toward the other side of the motor device. The electric power unit according to claim 11.

13. The aforementioned multiple secondary battery cells are When viewed from the axial direction of the rotation axis, the plurality of secondary battery cells constituting the first battery cell group are stacked on one side of the motor device and the plurality of secondary battery cells constituting the third battery cell group, When viewed from the axial direction of the rotation axis, the fourth battery cell group comprises a plurality of secondary battery cells stacked above the plurality of secondary battery cells comprising the second battery cell group, The electric power unit according to claim 11.

14. The aforementioned battery device The plurality of secondary battery cells further includes a plurality of tab terminals that are electrically and mechanically connected to two or more secondary battery cells, The plurality of tab terminals include a first tab terminal and a second tab terminal connected to a plurality of secondary battery cells that have the same arrangement as the plurality of secondary battery cells connected to the first tab terminal. The electric power unit according to claim 10.

15. A work machine comprising an electric power unit according to any one of claims 1, 4, or 5.

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