Electric working machine

Abstract

To provide an electric working machine mounted with a miniaturized outer rotor type brushless motor.SOLUTION: An aspect of the present disclosure provides an electric working machine including a brushless motor and a power transmission unit. The brushless motor is of an outer rotor type. The brushless motor includes a rotor and a stator. The rotor includes a rotor core and twelve magnetic poles. The rotor core includes a plurality of first core plates stacked on each other. The stator includes a stator core and nine coils. The stator core is disposed on an inner circumferential side of the rotor core and has nine teeth. The stator core includes a plurality of second core plates stacked on each other.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to an electric work machine equipped with an outer rotor type motor. [Background technology]

[0002] Patent Document 1 discloses an electric working machine equipped with an outer rotor type brushless motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-005814 Summary of the Invention [Problem to be solved by the invention]

[0004] In such electric working machines, it is desirable to reduce the size of the brushless motor in order to improve the workability of the electric working machine. Therefore, one aspect of the present disclosure has an object to provide an electric working machine equipped with a miniaturized outer rotor brushless motor. [Means for solving the problem]

[0005] In this disclosure, terms such as "first," "second," etc. are intended only to distinguish elements from one another and are not intended to limit the order or number of elements. Thus, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. In addition, a first element may be included without a second element, and similarly, a second element may be included without a first element.

[0006] One aspect of the present disclosure provides an electric working machine including a brushless motor and a power transmission unit. The brushless motor is an outer rotor type. The power transmission unit transmits rotational force of the brushless motor to a driven tool to drive the driven tool.

[0007] The brushless motor includes a rotor and a stator. The rotor includes a rotor core and 12 magnetic poles. The rotor core has a cylindrical shape. The rotor core includes a plurality of first core plates stacked on top of each other. The 12 magnetic poles are spaced apart from each other along the circumferential direction of the rotor core.

[0008] The stator includes a stator core and nine coils. The stator core is disposed on the inner periphery of the rotor core and has nine teeth. The stator core includes a plurality of second core plates stacked on top of each other. The nine coils are wound around the nine teeth, respectively.

[0009] In an electric working machine configured in this manner, it is possible to mount a compact outer rotor type brushless motor. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of an electric operating machine according to a first exemplary embodiment. [Figure 2] FIG. 2 is a first perspective view of a motor and a controller in an electric working machine. [Figure 3] FIG. 2 is a first exploded perspective view of the motor. [Figure 4] FIG. 2 is a second perspective view of the motor. [Figure 5] FIG. 2 is a second exploded perspective view of the motor. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] 1 is a cross-sectional view of the motor taken along a plane parallel to the right and forward directions and passing through the rotation axis AX. [Figure 9]FIG. 2 is a perspective view of a rotor core. [Figure 10] FIG. 4 is an explanatory diagram of a lamination process of the rotor core. [Figure 11] FIG. 2 is an exploded perspective view of a stator base, a stator core, and a first bearing. [Figure 12] FIG. 2 is an explanatory diagram specifically showing a state in which the stator cores are stacked; [Figure 13] FIG. [Figure 14] 2 is a cross-sectional view of the stator base, the stator core, and the first bearing, taken along a plane perpendicular to the rotation axis AX and passing through the first bearing. FIG. [Figure 15] FIG. 2 is an explanatory diagram showing the electrical configuration of the electric operating machine. [Figure 16] FIG. 1 is an explanatory diagram of various dimensions used when considering the optimum design of a motor. [Figure 17] FIG. 2 is an explanatory diagram of an induced voltage generated in a motor. [Figure 18] FIG. 10 is an explanatory diagram showing the results of examining the minimum value of the stator thickness Ds when the rotor core outer diameter φr is 55 mm. [Figure 19] FIG. 10 is an explanatory diagram showing the results of examining the minimum value of the stator thickness Ds when the rotor core outer diameter φr is 60 mm. [Figure 20] FIG. 10 is an explanatory diagram showing the results of examining the minimum value of the stator thickness Ds when the rotor core outer diameter φr is 65 mm. [Figure 21] FIG. 10 is an explanatory diagram showing the results of examining the minimum value of the stator thickness Ds when the rotor core outer diameter φr=70 [mm]. [Figure 22] FIG. 10 is an explanatory diagram showing the results of examining the minimum value of the stator thickness Ds when the rotor core outer diameter φr=75 [mm]. [Figure 23] FIG. 10 is an explanatory diagram showing the results of examining the minimum value of the stator thickness Ds when the rotor core outer diameter φr=80 [mm]. [Figure 24] FIG. 10 is an explanatory diagram showing the results of a study on the motor volume for a 12-pole, 9-slot motor. [Figure 25] FIG. 10 is an explanatory diagram showing the results of a study on the induced voltage constant k and the coefficient α. [Figure 26] FIG. 10 is an explanatory diagram showing the results of examining the rotor flatness density ξr when the motor output P is 1.0 kW. [Figure 27] FIG. 10 is an explanatory diagram showing the results of examining the rotor flatness density ξr when the motor output P is 1.5 kW. [Figure 28] FIG. 10 is an explanatory diagram showing the results of examining the rotor aspect ratio density ξr when the motor output P is 2.0 kW. [Figure 29] FIG. 10 is an explanatory diagram showing the results of examining the rotor flatness density ξr when the motor output P is 2.4 kW. [Figure 30] FIG. 10 is an explanatory diagram showing the results of examining the stator flattening density ξs when the motor output P is 1.0 kW. [Figure 31] FIG. 10 is an explanatory diagram showing the results of examining the stator flattening density ξs when the motor output P is 1.5 kW. [Figure 32] FIG. 10 is an explanatory diagram showing the results of examining the stator flattening density ξs when the motor output P is 2.0 kW. [Figure 33] FIG. 10 is an explanatory diagram showing the results of examining the stator flattening density ξs when the motor output P is 2.4 kW. [Figure 34] FIG. 10 is an explanatory diagram showing an example of a pole-slot combination that can realize a small size and light weight. [Figure 35] FIG. 10 is a perspective view of a rotor according to a second embodiment. [Figure 36] FIG. 10 is a perspective view of a rotor according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] [1. Overview of the embodiment] An embodiment may provide an electric power tool including at least one of the following: Feature 1: Brushless motor. · Feature 2: The brushless motor is an outer rotor type. ·Feature 3: Power transmission unit. Feature 4: The power transmission unit is configured to transmit the rotational force of the brushless motor to the driven tool to drive the driven tool. · Feature 5: Brushless motors have a rotor. Feature 6: The rotor includes a rotor core. Feature 7: The rotor core has a plurality of first core plates stacked on top of each other. Feature 8: The rotor core has a cylindrical shape. Feature 9: The rotor has 12 magnetic poles (or magnetic pole sections). Feature 10: The 12 magnetic poles are spaced apart from one another along the circumferential direction of the rotor core. Feature 11: The brushless motor includes a stator. Feature 12: The stator includes a stator core. Feature 13: The stator core is located on the inner periphery of the rotor core. Feature 14: The stator core has a plurality of second core plates stacked on top of each other. Feature 15: The stator core has nine teeth. Feature 16: The stator has nine coils. Feature 17: Nine coils are wound around nine teeth.

[0012] An electric work machine having at least Features 1 to 17 can be equipped with a compact outer rotor brushless motor. In addition, it may be possible to increase the output of the brushless motor (i.e., miniaturization and high output).

[0013] Furthermore, feature 7 enables a reduction in eddy currents generated in the rotor core (and thus a reduction in eddy current loss in the rotor core). Feature 14 enables a reduction in eddy currents generated in the stator core (and thus a reduction in eddy current loss in the stator core).

[0014] The circumferential direction may be the rotation direction of the rotor core, i.e., the rotation direction of the rotor. The rotor core may have a cylindrical shape. Each of the 12 magnetic poles may be arranged to face the rotation axis of the rotor, i.e., each of the 12 magnetic poles may be arranged so that the north pole and south pole of that magnetic pole are aligned along the radial direction.

[0015] The 12 magnetic poles may be arranged so that north and south poles alternate in the circumferential direction as viewed from the stator (that is, facing the stator). In other words, the 12 magnetic poles may be arranged so that the north poles and south poles alternately face each other on a predetermined outer peripheral surface of the stator core as the rotor core rotates.

[0016] The 12 magnetic poles may be realized in any specific manner, and may be realized by 12 magnets (for example, permanent magnets) as described below. The rotor core may be supported by a support member. The support member may have a cup-like shape. The rotor core may be fixed to the inner periphery of the support member. Specifically, the outer periphery of the rotor core may be fixed (for example, adhesively fixed) to the inner periphery of the support member.

[0017] The rotor may include a shaft configured to rotate integrally with the rotor. The shaft may be directly or indirectly connected to a power transmission unit, and the rotational force of the brushless motor (i.e., the rotational force of the rotor) may be transmitted to the power transmission unit via the shaft.

[0018] Each of the plurality of first core plates may have a plate-like (or thin plate-like) shape. Each of the plurality of first core plates may include a magnetic material (or magnetic substance). More specifically, each of the plurality of first core plates may include a soft magnetic material. Even more specifically, each of the plurality of first core plates may include electromagnetic steel, i.e., may be an electromagnetic steel plate.

[0019] The above matters regarding the plurality of first core plates also apply to the plurality of second core plates. The rotor core may have an inner peripheral surface, and the stator core may be arranged such that the outer peripheral surface of the stator core faces the inner peripheral surface of the rotor core.

[0020] The stator core may include a cylindrical back core. The nine teeth may be arranged to extend radially outward from the back core. The nine teeth may be formed integrally with the back core. The nine teeth may be arranged at equal intervals along the circumferential direction. A space between two circumferentially adjacent teeth may be referred to as a slot. In this case, the stator core having nine teeth may be rephrased as the stator core having nine slots. The nine coils may be wound around the stator core using a so-called concentrated winding method.

[0021] The nine coils may be connected to each other in any manner, including delta-connected or star-connected, as will be described later. The nine coils may be configured to be supplied with electrical power (e.g., three-phase power). The nine coils may be configured to receive the electrical power and generate a magnetic force therefrom. The rotor may be configured to rotate in response to changes in the magnetic force generated by the nine coils.

[0022] The rotor having 12 magnetic poles may mean that the rotor has no more than 13 magnetic poles. The stator core having 9 teeth may mean that the stator core has no more than 10 teeth (in other words, no more than 10 slots).

[0023] The driven tool may be fixed to the electric working machine in an undetachable manner, or may be configured to be detachably attached to the electric working machine. Some embodiments may include at least one of the following in addition to or instead of at least one of Features 1 to 17 above. Feature 18: The brushless motor has an induced voltage constant k [V / krpm] that satisfies the condition 1.1≦k≦9.0. Feature 19: The induced voltage constant k is calculated using the formula E / N. Feature 20: In the formula for Feature 19, N [krpm] is the rotation speed of the brushless motor. Feature 21: In the formula of Feature 19, E [V] is a value indicating the magnitude of the induced voltage generated in the brushless motor. E [V] may be a value indicating the magnitude of the induced voltage when the brushless motor is rotating at a rotation speed N.

[0024] In an electric working machine having at least Features 1 to 21, it is possible to reduce the size of the outer rotor brushless motor mounted on the electric working machine. In addition, it may be possible to increase the output of the brushless motor (i.e., to reduce the size and increase the output).

[0025] Here, the "value indicating the magnitude of the induced voltage" is referred to as the "effective induced voltage value." Induced voltages can be generated in nine coils. The effective induced voltage value may indicate the magnitude of the induced voltage generated in each (or any one) of the nine coils.

[0026] If the stator has a first coil group, a second coil group, and a third coil group that are delta-connected to each other as described below, and each of the first to third coil groups includes three coils out of nine coils, the effective induced voltage value may indicate the magnitude of the induced voltage of any of the first to third coil groups.

[0027] The brushless motor may include a first terminal, a second terminal, and a third terminal connected to nine coils and configured to supply power (e.g., three-phase power) to the nine coils. In this case, the effective induced voltage value may indicate the magnitude of the induced voltage generated between any two of the first to third terminals. When the nine coils are delta-connected, the first terminal may be connected to a connection point between the first coil group and the second coil group (hereinafter referred to as the "first connection point"), the second terminal may be connected to a connection point between the second coil group and the third coil group (hereinafter referred to as the "second connection point"), and the third terminal may be connected to a connection point between the third coil group and the first coil group (hereinafter referred to as the "third connection point").

[0028] The induced voltage can change periodically (for example, sinusoidally) depending on the rotational position (or rotational angle) of the brushless motor. Every time the rotor rotates through a mechanical angle equivalent to 360 electrical degrees, the induced voltage changes by one period.

[0029] The mechanical angle is the actual rotation angle of the rotor. The relationship between the electrical angle and the mechanical angle depends on the number of poles of the brushless motor. For example, if the brushless motor has two magnetic poles, one mechanical angle corresponds to one electrical angle. If the brushless motor has 12 magnetic poles, one mechanical angle corresponds to six electrical angles. In this case, the rotor actually rotating 60 degrees is equivalent to the rotor rotating 360 electrical degrees.

[0030] The effective induced voltage value E indicates the magnitude (or substantial magnitude) of the induced voltage that changes periodically as described above. The effective induced voltage value E may be determined in any manner. For example, the effective induced voltage value E may be the effective value of the induced voltage or the average value of the absolute values ​​of the induced voltage. Furthermore, for example, the effective induced voltage value E may be the average value of the induced voltage over a predetermined section within one period of the electrical angle, or the induced voltage value (i.e., the instantaneous value) at a predetermined electrical angle. The predetermined section may include, for example, the electrical angle ωem at which the induced voltage is at its maximum value. The electrical angle ωem may be the center of the predetermined section. The width of the predetermined section may be determined as appropriate, and may be, for example, 60 degrees.

[0031] The induced voltage constant k may satisfy a condition other than 1.1≦k≦9.0. The induced voltage constant k may, for example, satisfy a condition of being greater than or equal to a first threshold value and less than or equal to a second threshold value. The first threshold value may be less than or equal to 1.1. The first threshold value may be, for example, 1.13. The second threshold value may be less than or equal to 9.0. The induced voltage constant k may, for example, be greater than or equal to 2.25 and less than or equal to 4.50, greater than or equal to 1.13 and less than or equal to 2.25, or greater than or equal to 4.50 and less than or equal to 9.0.

[0032] Some embodiments may include at least one of the following in addition to or instead of at least one of Features 1 to 21 above. Feature 22: The coefficient α [mΩ / (V / krpm) of the brushless motor satisfies the condition 0.2≦α≦19.0. 2 ]. Feature 23: The coefficient α is calculated using the formula R / k 2 It is calculated as follows. Feature 24: In the formula of Feature 23, R [mΩ] is a motor resistance value based on the resistance value of at least one of the nine coils. Feature 25: In the formula of Feature 23, k [V / krpm] is the induced voltage constant calculated by the aforementioned formula E / N.

[0033] An electric working machine having at least Features 1 to 17 and 22 to 25 can reduce the size of the outer rotor brushless motor mounted on the electric working machine. In addition, it may be possible to increase the output of the brushless motor (i.e., reduce the size and increase the output).

[0034] The motor resistance may be the resistance between two predetermined positions in a circuit containing nine coils. When the brushless motor includes the first to third coil groups described above, the motor resistance value may be the resistance value between any two of the first to third connection points described above.

[0035] When the brushless motor has the first to third terminals described above, the motor resistance value may be the resistance value between any two of the first to third terminals. The coefficient α may satisfy a condition other than 0.2≦α≦19.0. The coefficient α may satisfy, for example, a condition of being greater than or equal to a third threshold and less than or equal to a fourth threshold. The third threshold may be less than or greater than 0.2. The third threshold may be, for example, 0.27, 0.4, or 0.54. The fourth threshold may be less than or greater than 19.0. The fourth threshold may be, for example, 1.63, 6.08, or 18.96. Specifically, the coefficient α may satisfy, for example, a condition of 0.4≦α≦19.0.

[0036] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1 to 25 above. Feature 26: The rotor core has an outer diameter φr [mm] that satisfies the condition 55≦φr≦80. Feature 27: The rotor core outer diameter φr is the outer diameter of the rotor core. More specifically, the rotor core outer diameter φr may be the length in the radial direction of the rotor core. The radial direction is perpendicular to the rotation axis of the rotor.

[0037] An electric working machine having at least Features 1 to 17, 26, and 27 can reduce the size of the outer rotor brushless motor mounted on the electric working machine. In addition, it may be possible to increase the output of the brushless motor (i.e., reduce the size and increase the output).

[0038] Some embodiments may include at least one of the following in addition to or instead of at least one of Features 1-27 above. Feature 28: The stator core has an outer diameter φs [mm] that satisfies the condition 40≦φs≦72.5. Feature 29: The stator core outer diameter φs is the outer diameter of the stator core. More specifically, the stator core outer diameter φr may be the length of the stator core in the radial direction.

[0039] An electric working machine having at least Features 1 to 17, 28, and 29 can reduce the size of the outer rotor brushless motor mounted on the electric working machine. In addition, it may be possible to increase the output of the brushless motor (i.e., reduce the size and increase the output).

[0040] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-29 above. Feature 30: The brushless motor has a rotor flatness ηr that satisfies the condition 0.1≦ηr≦0.7. Feature 31: The rotor flatness ηr is calculated using the formula Ds / φr. Feature 32: In the formula of Feature 31, Ds [mm] is the axial length of the stator core, and the axial direction is parallel to the rotation axis of the rotor. Feature 33: In the formula of Feature 31, φr [mm] is the outer diameter of the rotor core.

[0041] An electric working machine having at least Features 1 to 17 and 30 to 33 can reduce the size of the outer rotor brushless motor mounted on the electric working machine. In addition, it may be possible to increase the output of the brushless motor (i.e., reduce the size and increase the output).

[0042] Some embodiments may include at least one of the following in addition to or instead of at least one of Features 1 to 33 above. Feature 34: The brushless motor has a stator flatness ηs that satisfies the condition 0.1≦ηs≦0.8. Feature 35: The stator flatness ηs is calculated using the formula Ds / φs. Feature 36: In the formula of Feature 35, Ds [mm] is the axial length of the stator core. Feature 37: In the formula of Feature 35, φs [mm] is the outer diameter of the stator core.

[0043] In an electric working machine having at least Features 1 to 17 and 34 to 37, it is possible to reduce the size of the outer rotor brushless motor mounted on the electric working machine. In addition, it may be possible to increase the output of the brushless motor (i.e., to reduce the size and increase the output).

[0044] Some embodiments may include at least one of the following in addition to or instead of at least one of Features 1-37 above. Feature 38: The brushless motor has a rotor flatness density ξr [ / kW] that satisfies the condition fr2≦ξr≦fr1. Feature 39: The rotor aspect ratio density ξr is calculated using the formula ηr / P. Feature 40: In the formula of Feature 39, ηr is calculated using the formula Ds / φr. Feature 41: In the formula of Feature 40, Ds [mm] is the axial length of the stator core. Feature 42: In the formula of Feature 40, φr [mm] is the outer diameter of the rotor core. Feature 43: In the formula of Feature 39, P [kW] is the output of the brushless motor. Feature 44: fr1 satisfies the following equation.

[0045] fr1=0.000465φr 2 -0.0782φr+3.43 Feature 45: fr2 satisfies the following equation. fr2=0.000443φr 2 -0.0698φr+2.79 Feature 46: The rotor core outer diameter φr [mm] satisfies 55≦φr≦80.

[0046] In an electric working machine having at least Features 1 to 17 and 38 to 46, it is possible to reduce the size of the outer rotor brushless motor mounted on the electric working machine. In addition, it may be possible to increase the output of the brushless motor (i.e., to reduce the size and increase the output).

[0047] The output P may be the output when the rotor rotates at a predetermined rotation speed. The predetermined rotation speed may be the rated rotation speed, the rotation speed when no load is applied to the electric working machine from outside, or the rotation speed when no load is applied to the rotor itself (i.e., the rotation speed of the brushless motor alone).

[0048] The predetermined rotation speed may be, for example, 14,000 [rpm] or 12,000 [rpm]. ] may also be used. The output power P may be a predetermined value, for example, between 1.0 kW and 2.4 kW. The output power P may be a predetermined value, for example, between 1.5 kW and 2.4 kW. The output power P may be, for example, 1.5 kW.

[0049] Some embodiments may include at least one of the following in addition to or instead of at least one of Features 1-46 above. Feature 47: The brushless motor has a stator flatness density ξs [ / kW] that satisfies the condition fs2≦ξs≦fs1. Feature 48: The stator flatness density ξs is calculated using the formula ηs / P. Feature 49: In the formula of Feature 48, ηs is calculated using the formula Ds / φs. Feature 50: In the formula of Feature 49, Ds [mm] is the axial length of the stator core. Feature 51: In the formula of Feature 49, φs [mm] is the outer diameter of the stator core. Feature 52: In the formula of Feature 48, P [kW] is the output of the brushless motor mentioned above. Feature 53: fs1 satisfies the following equation.

[0050] fs1=0.00105φs 2 -0.144φs+5.13 Feature 54: fs2 satisfies the following equation. fs2=0.000665φs 2 -0.0887φs+3.00 Feature 55: The outer diameter φs [mm] of the stator core satisfies 45≦φs≦70.

[0051] In an electric working machine having at least Features 1 to 17 and 47 to 55, it is possible to reduce the size of the outer rotor brushless motor mounted on the electric working machine. In addition, it may be possible to increase the output of the brushless motor (i.e., to reduce the size and increase the output).

[0052] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1 to 55 above. Feature 56: The rotor core has 12 magnet parts. Feature 57: The 12 magnet sections are spaced apart from one another along the direction of rotation of the rotor core. Feature 58: Each of the 12 magnet sections has one or more permanent magnets. Feature 59: Each of the 12 magnet parts forms a corresponding one of the 12 magnetic poles.

[0053] An electric operating machine having at least features 1 to 17 and 56 to 59 can easily achieve 12 magnetic poles. The twelve magnet portions may be completely embedded in the rotor core, or may be fixed to the inner peripheral surface of the rotor core so as to be exposed on the stator side, as will be described later.

[0054] Some embodiments may include the following in addition to or instead of at least one of features 1-59 above. Feature 60: The one or more permanent magnets include a sintered magnet containing neodymium, iron, and boron.

[0055] In an electric operating machine having at least features 1 to 17 and 56 to 60, it is possible to prevent the one or more permanent magnets from becoming too large, while generating a magnetic force of an appropriate (or necessary and sufficient) magnitude from the one or more permanent magnets.

[0056] Each of the one or more permanent magnets (hereinafter simply referred to as "permanent magnets") may be a so-called Nd-Fe-B magnet, which is primarily composed of neodymium (Nd), iron (Fe), and boron (B).

[0057] In another embodiment, the permanent magnet may be an Fe—N magnet, which is primarily composed of iron (Fe) and nitrogen (N). In another embodiment, the permanent magnet may be a Sm-Fe-N magnet, which is primarily composed of samarium (Sm), iron (Fe), and nitrogen (N).

[0058] In another embodiment, the permanent magnet may be a Sm-Fe magnet, which is primarily composed of samarium (Sm) and iron (Fe). In another embodiment, the permanent magnet may be a sintered magnet or a magnet different from a sintered magnet (for example, a bonded magnet).

[0059] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-60 above. Feature 61: The 12 magnets are attached to the inner surface of the rotor core.

[0060] Feature 61 may mean that the brushless motor is a so-called SPM type motor. "SPM" is an abbreviation for "Surface Permanent Magnet."

[0061] In an electric operating machine having at least the features 1 to 17, 56 to 59, and 61, the twelve magnet portions can be easily attached to the rotor core. Some embodiments may include the following in addition to or instead of at least one of features 1-61 above. Feature 62: Each of the 12 magnet units includes two or more permanent magnets that are independent of each other.

[0062] In an electric operating machine having at least the features 1 to 17, 56 to 59, and 62, it is possible to reduce the eddy currents generated in each magnet section (and thus reduce the eddy current loss in each magnet section). Some embodiments may include the following in addition to or instead of at least one of features 1-62 above. Feature 63: In each of the 12 magnet sections, two or more permanent magnets are arranged along the radial direction of the rotor core.

[0063] In an electric operating machine having at least the features 1 to 17, 56 to 59, 62, and 63, eddy currents generated in each magnet portion can be easily reduced. Some embodiments may include the following in addition to or instead of at least one of features 1-63 above. Feature 64: In each of the 12 magnet sections, two or more permanent magnets are arranged along the rotation axis of the rotor core.

[0064] In an electric operating machine having at least the features 1 to 17, 56 to 59, 62, and 64, eddy currents generated in each magnet portion can be easily reduced. Each of the first to third coil groups may have a first end and a second end. The first end of the first coil group may be connected to the second end of the third coil group, the second end of the first coil group may be connected to the first end of the second coil group, and the second end of the second coil group may be connected to the first end of the third coil group.

[0065] Some embodiments may include the following in addition to or instead of at least one of features 1-64 above. Feature 65: The nine coils are delta-connected to each other.

[0066] In an electric working machine having at least the features 1 to 17 and 65, it is possible to improve the output of the brushless motor while preventing the coil from becoming thicker. Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-65 above. Feature 66: The stator includes a first coil group, a second coil group, and a third coil group that are delta-connected to one another. Feature 67: The first coil group includes three coils of the nine coils that are connected in parallel to each other. Feature 68: The second coil group includes three coils out of the nine coils that are different from the first coil group and are connected in parallel to each other. Feature 69: The third coil group includes three coils out of the nine coils that are different from either the first coil group or the second coil group and are connected in parallel to each other.

[0067] In an electric working machine having at least the features 1 to 17 and 65 to 69, it is possible to improve the output of the brushless motor while preventing the coil from becoming thicker. Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-69 above. Feature 70: The stator core has a slot opening width Wso [mm] that satisfies 0.04φs≦Ws≦0.18φs. Feature 71: The slot opening width Wso is the linear distance along the circumferential direction of the radially outer opening between two circumferentially adjacent teeth out of the nine teeth.

[0068] The stator core may have nine openings. The slot opening widths Wso of the nine openings may be equal to each other. In an electric working machine having at least the features 1 to 17, 7, and 71, it is possible to reduce the size of the brushless motor while maintaining the ease of winding the coil around the teeth.

[0069] In other words, the slot opening width Wso is the linear distance along the circumferential direction of the radially outer opening of each of the nine slots. Each of the nine teeth may have a main body portion extending radially outward from the back core and a flange-shaped tip portion provided at an end of the main body portion. In this case, the distance between two circumferentially adjacent tip portions may be defined as the slot opening width Wso.

[0070] Some embodiments may include at least one of the following in addition to or instead of at least one of Features 1 to 71 above. Feature 72: The electric work machine has a gripping portion. ·Feature 73: The grip portion is configured to be gripped by a user of the electric working machine. ·Feature 74: The electric working machine includes a battery mounting portion. Feature 75: The battery mounting section is configured so that the battery pack can be removably mounted. Feature 76: The battery pack includes a battery.

[0071] An electric working machine having at least the features 1 to 17 and 72 to 76 allows for the miniaturization of a battery-powered electric working machine having an outer rotor type brushless motor. Examples of the electric working machine described above include various devices configured to be used at work sites such as construction, manufacturing, gardening, and civil engineering, specifically, power tools for masonry, metalwork, and woodworking, power tools for gardening, and the like. This includes tools, power tools to improve the work environment, fan vests, fan jackets, push carts, electric assist bicycles, air pumps, etc.

[0072] Examples of the power tools mentioned above include electric chainsaws, electric hand saws, electric blowers, electric hammers, electric hammer drills, electric drills, electric screwdrivers, electric wrenches, electric impact drivers, electric impact wrenches, electric grinders, electric circular saws, electric reciprocating saws, electric jigsaws, electric cutters, electric planers, electric nail guns (including tackers), electric hedge trimmers, electric lawn mowers, electric lawn clippers, electric brush cutters, electric cleaners, electric sprayers, electric spreaders, electric dust collectors, electric trowels, electric vibrators, electric rammers, electric compactors, electric pumps, electric pile drivers, electric concrete saws, electric screeds, electric cut-off saws, electric fans, and the like.

[0073] Examples of driven implements include a saw chain in an electric chainsaw, an electric screwdriver, a driver bit in an electric drill or electric wrench, a drill bit, a socket bit, a saw blade in an electric circular saw, a cutting blade in an electric brush cutter, and blades in an electric fan.

[0074] The above-mentioned examples of electric working machines may be in the form of battery-powered equipment having a built-in battery. In some embodiments, the above features 1 to 76 may be combined in any manner.

[0075] In some embodiments, any of the above features 1-76 may be omitted. 2. SPECIFIC EXEMPLARY EMBODIMENTS A specific exemplary embodiment will be described below. This specific exemplary embodiment provides an electric work machine 1 in the form of an electric chainsaw. However, this electric work machine 1 is merely an example, and the present disclosure may be applied to any form of electric work machine.

[0076] [2-1. First embodiment] [2-1-1. Overall configuration of electric work machine] As shown in Fig. 1, the electric work machine 1 includes a housing (or enclosure) 2. The housing 2 is made of synthetic resin. The housing 2 accommodates a motor 6 therein. The housing 2 accommodates a controller 11 therein.

[0077] For ease of explanation, in this embodiment, the directions of "up," "down," "right," "left," "front," and "rear" are defined with the electric working machine 1 at the center, as shown in Figure 1 and subsequent figures. The electric working machine 1 is provided with a guide bar 9. The guide bar 9 is a plate-shaped member. The guide bar 9 protrudes from the housing 2 to the front of the electric working machine 1.

[0078] The electric work machine 1 is equipped with a saw chain 10. The saw chain 10 includes a plurality of cutters connected to one another. The saw chain 10 is removably attached to the periphery of a guide bar 9. The saw chain 10 corresponds to an example of a driven tool in the summary of the embodiments.

[0079] The electric work machine 1 includes a power transmission unit 13. The power transmission unit 13 is directly or indirectly connected to a rotor shaft 50 (see FIG. 2 ) of the motor 6. The saw chain 10 is connected to the motor 6 via the power transmission unit 13. The power transmission unit 13 includes a sprocket (not shown) configured to have the saw chain 10 attached thereto. The power transmission unit 13 transmits the rotation of the motor 6 (more specifically, the rotation of the rotor shaft 50) to the saw chain 10, thereby driving the saw chain 10.

[0080] Therefore, when the motor 6 is driven, the saw chain 10 moves around the periphery of the guide bar 9. The electric work machine 1 can cut the workpiece with the moving saw chain 10.

[0081] The electric work machine 1 is equipped with a battery mounting portion 5. In this embodiment, the battery mounting portion 5 protrudes upward from the rear of the housing 2. A battery pack 12 is removably mounted to the battery mounting portion 5. The battery pack 12 can be attached to the rear end face of the battery mounting portion 5.

[0082] The battery pack 12 includes a battery. The battery is in the form of a rechargeable secondary battery. The battery may be, for example, a lithium-ion secondary battery. The battery may also be a non-rechargeable primary battery. The rated voltage of the battery in this embodiment is 36V. However, the rated voltage of the battery may be different from 36V.

[0083] The battery pack 12 can supply battery power to the electric work machine 1 by being attached to the battery attachment section 5. The battery power is output from the battery. The motor 6 receives the battery power from the battery pack 12 via the controller 11 and is driven by it.

[0084] The electric working machine 1 is provided with a hand guard 4. The hand guard 4 protrudes upward from the front of the housing 2. The electric work machine 1 is provided with a side handle 3A and a top handle 3B behind the hand guard 4. One of the side handle 3A and the top handle 3B may be omitted. The side handle 3A and the top handle 3B are made of synthetic resin.

[0085] The side handle 3A is a pipe-shaped member that protrudes leftward from the left part of the housing 2. Therefore, the operator of the electric working machine 1 can grip the side handle 3A with his / her left hand from behind the electric working machine 1.

[0086] The top handle 3B protrudes upward from the top of the housing 2. The rear end of the top handle 3B is connected to the battery attachment section 5, which forms a space between the top handle 3B and the housing 2. Therefore, the operator can insert his or her fingers into this space to grip the top handle 3B.

[0087] The electric work machine 1 is provided with a trigger switch 7 below the top handle 3B. The trigger switch 7 is operated (for example, pulled) by the operator to drive the motor 6. When the trigger switch 7 is pulled upward by the operator, the motor 6 is driven. When the operation of the trigger switch 7 is released, the driving of the motor 6 is stopped.

[0088] The electric work machine 1 is provided with a trigger lock lever 8 above the top handle 3B. When the trigger lock lever 8 is pressed downward by the operator, operation of the trigger switch 7 is permitted.

[0089] The specific configuration of the motor 6 will be described below with reference to FIGS. [2-1-2. Specific motor configuration] In this embodiment, the motor 6 is an outer rotor brushless motor. More specifically, the motor 6 in this embodiment is a 12-pole, 9-slot brushless motor. That is, the motor 6 has 12 magnetic poles and 9 slots 34 (see FIG. 7).

[0090] 2 to 6 and 8, the motor 6 includes a rotor 20. The motor 6 includes a stator 30. The rotor 20 is disposed on the outer periphery of the stator 30 and rotates around the stator 30 .

[0091] The motor 6 includes a rotor shaft 50. The rotor shaft 50 is fixed to the rotor 20. The central axis of the rotor shaft 50 coincides with the rotation axis AX of the motor 6. Therefore, the rotor 20 and the rotor shaft 50 rotate about the rotation axis AX.

[0092] The motor 6 includes a sensor board 60. The sensor board 60 includes three magnetic sensors 62A, 62B, and 62C that detect the rotation of the rotor 20. The motor 6 includes a stator base 40. The stator base 40 supports the stator 30 and the sensor board 60.

[0093] The motor 6 includes an insulating member 70. The insulating member 70 is disposed between the stator base 40 and the stator 30. The insulating member 70 has a hollow disk shape. A second support portion 41B, which will be described later, is inserted into the inner hole of the insulating member 70 (see FIG. 8).

[0094] The rotor shaft 50 passes through the stator 30, the insulating member 70, and the stator base 40 from the rotor 20 and protrudes to the outside. The rotor shaft 50 is provided with an output shaft 51. The output shaft 51 corresponds to a part of the rotor shaft 50 that includes the first end protruding to the outside from the stator base 40. The output shaft 51 is directly or indirectly connected to the power transmission unit 13. The rotor shaft 50 drives the saw chain 10 via the power transmission unit 13.

[0095] The main components of the motor 6, including the rotor 20, the stator 30, and the stator base 40, will be described in more detail below with reference to FIGS. [2-1-2a. Rotor] 2 to 6 and 8, the rotor 20 includes a rotor cup 21. The rotor cup 21 is made of metal. Specifically, the rotor cup 21 contains aluminum, which is a non-magnetic material, as its main component.

[0096] The rotor cup 21 includes a plate portion 21A. The plate portion 21A has an annular shape. The plate portion 21A includes an opening 21C in its center. The rotor shaft 50 is inserted into the opening 21C and fixed therein. The rotor shaft 50 may be fixed to the rotor cup 21 by any method. In this embodiment, the rotor shaft 50 is press-fitted into the opening 21C and thereby fixed to the opening 21C (and thus to the rotor cup 21).

[0097] The rotor cup 21 includes a yoke portion 21B. The yoke portion 21B has a cylindrical shape. The yoke portion 21B surrounds the rotor shaft 50. The rotor cup 21 includes a plurality of fins 21D between the plate portion 21A and the yoke portion 21B. The yoke portion 21B is connected to the outer periphery of the plate portion 21A via the plurality of fins 21D. The plurality of fins 21D are arranged at equal intervals along the outer periphery of the plate portion 21A. The plurality of fins 21D rotate together with the plate portion 21A (in other words, the rotor 20), thereby generating wind. The wind cools the motor 6.

[0098] As shown in Figures 4 to 6, 8 and 9, the rotor 20 includes a rotor core 22. As shown in a partially enlarged view in Figure 9, the rotor core 22 includes a plurality of first core plates 2200 stacked in a direction along the rotation axis AX (hereinafter referred to as the "axial direction"). 4 to 6 and 8, rotor core 22 is supported on the inner peripheral surface of yoke portion 21B of rotor cup 21. Rotor core 22 has a substantially cylindrical shape.

[0099] Each of the plurality of first core plates 2200 has a plate shape and includes a soft magnetic material. Each of the plurality of first core plates 2200 is, for example, an electromagnetic steel plate. The rotor core 22 is in the form of a laminate in which the plurality of first core plates 2200 are stacked.

[0100] The lamination configuration of rotor core 22 will be described in more detail with reference to Fig. 10. First core plate 2200 has first surface 2200A and second surface 2200B. A protrusion 2201 is formed on the first surface 2200A. The protrusion 2201 is also shown in Fig. 9. A recess 2202 is formed on the second surface 2200B. The recess 2202 is provided at a position on the second surface 2200B that overlaps with the protrusion 2201 in the axial direction.

[0101] In the process of stacking the multiple first core plates 2200, the recess 2202 of one of the two opposing first core plates 2200 is fitted into the protrusion 2201 of the other. As a result, as shown in Fig. 10, a rotor core 22 (i.e., lamination) is formed in which the multiple first core plates 2200 are stacked in close contact with each other in the axial direction.

[0102] When the protrusion 2201 is fitted into the recess 2202, the pressure (and / or frictional force) acting between the protrusion 2201 and the recess 2202 prevents (or makes it difficult for) the protrusion 2201 to come out of the recess 2202.

[0103] In this embodiment, when the protrusion 2201 is fitted into the recess 2202, the protrusion 2201 and / or the recess 2202 are mechanically deformed (elastically or plastically deformed) by the pressure they receive when fitted in. This mechanical deformation causes the protrusion 2201 to be crimped into the recess 2202, so that the protrusion 2201 cannot (or does not easily) come out of the recess 2202.

[0104] The first core plates 2200 may be fixed to one another (i.e., integrated) by any method. For example, instead of or in addition to the above-described crimping, they may be fixed to one another by another method. Other methods may include, for example, adhesive fixing or laser welding.

[0105] As shown in detail in Figure 6, the rotor 20 has 12 magnetic poles. In Figure 6, the text "S" in a dashed circle indicates a south pole, and the text "N" in a dashed circle indicates a north pole. The 12 magnetic poles are arranged at equal (or approximately equal) intervals along the circumferential direction. Each of the 12 magnetic poles faces the axis of rotation AX.

[0106] In order to form 12 magnetic poles, the rotor 20 of this embodiment is provided with 12 magnets 23. In the following description, when the term "magnet 23" is simply used, it refers to each of the 12 magnets 23 unless otherwise specified.

[0107] The magnet 23 is a permanent magnet. The magnet 23 has a plate-like shape. In this embodiment, the magnet 23 is in the form of a sintered magnet. The magnet 23 in this embodiment is an Nd—Fe—B magnet. However, the magnet 23 may be a magnet other than an Nd—Fe—B magnet. The magnet 23 may be, for example, an Fe—N magnet, an Sm—Fe—N magnet, or an Sm—Fe magnet. The magnet 23 may be in a form other than a sintered magnet (for example, a bonded magnet).

[0108] The twelve magnets 23 are arranged at intervals from one another along the circumferential direction on the inner circumferential surface of the rotor core 22. The magnets 23 are fixed to the inner circumferential surface of the rotor core 22 by, for example, an adhesive. Each is fixed.

[0109] As shown in Figure 6, the magnets 23 are arranged so that their two magnetic poles (north and south poles) are aligned in the radial direction. The radial direction is perpendicular to the rotation axis AX. That is, the magnets 23 are arranged so that one of their magnetic poles faces the rotation axis AX and the other faces in the opposite direction from the rotation axis AX. The twelve magnets 23 are arranged so that their north and south poles alternately face the rotation axis AX along the circumferential direction.

[0110] [2-1-2b. Stator] The stator 30 is disposed on the inner circumferential side of the rotor core 22. That is, the stator 30 is disposed so as to face the twelve magnets 23 in the radial direction.

[0111] As shown in Figures 3, 5, 7, and 8, the stator 30 includes a stator core 31. The stator core 31 is made of electromagnetic steel. More specifically, as shown in the simplified enlarged view of Figure 11, the stator core 31 includes a plurality of second core plates 3100. Each of the second core plates 3100 has a plate-like shape and includes a soft magnetic material. Each of the second core plates 3100 is, for example, an electromagnetic steel plate. The second core plates 3100 are stacked one on top of the other along the axial direction. In other words, the stator core 31 is in the form of a laminate in which the second core plates 3100 are stacked one on top of the other.

[0112] The stator core 31 is formed in the same manner as the rotor core 22, that is, by the same process as that shown in FIG. That is, as shown in Fig. 12, each second core plate 3100 has a protrusion 3101 formed on its first surface and a recess 3102 formed on its second surface. The protrusion 3101 is also shown in Fig. 11. The recess 3102 is provided at a position overlapping the protrusion 3101 in the axial direction.

[0113] In the process of stacking multiple second core plates 3100, the protrusion 3101 of one of two opposing second core plates 3100 is fitted into the recess 3102 of the other. As a result, as shown in Fig. 12, a stator core 31 (i.e., lamination) is formed in which multiple second core plates 3100 are stacked in close contact with each other in the axial direction.

[0114] Furthermore, similarly to the rotor core 22, when the protrusions 3101 are fitted into the recesses 3102, the protrusions 3101 are crimped into the recesses 3102, and the protrusions 3101 do not (or are difficult to) come out of the recesses 3102. Note that the multiple second core plates 3100 may be fixed to one another (i.e., integrated) by any method. For example, instead of or in addition to the above-described crimping fixation, they may be fixed to one another by another method. The other method may include, for example, adhesive fixation with an adhesive or laser welding.

[0115] The stator core 31 includes a yoke (or stator back) 31A. The yoke 31A has a cylindrical shape. Specifically, as shown in FIGS. 7 and 8, the yoke 31A includes a through hole 310. The stator base 40 is inserted into the through hole 310, and the rotor shaft 50 is inserted into the stator base 40. In other words, the rotor shaft 50 passes through the through hole 310 via the stator base 40. The central axis of the yoke 31A (i.e., the central axis of the through hole 310) coincides with the rotation axis AX. The through hole 310 will be described in more detail later with reference to FIGS. 11, 13, and 14.

[0116] The stator core 31 has nine teeth 31B. The nine teeth 31B protrude radially outward from the outer peripheral surface of the yoke 31A. The nine teeth 31B are arranged at intervals along the circumferential direction. In this embodiment, the nine teeth 31B are The nine teeth 31B are arranged at equal intervals along the circumferential direction and are integrally formed with the yoke 31A.

[0117] 7, a slot 34 is formed between two circumferentially adjacent teeth 31B. That is, the stator 30 has nine slots 34 arranged along the circumferential direction.

[0118] 3, 5, 7, and 8, the stator 30 includes an insulator 32. The insulator 32 is made of, for example, a synthetic resin. The insulator 32 covers at least a portion of the surface of the stator core 31.

[0119] The stator 30 has nine coils 33. Each of the nine coils 33 has a wire. Specifically, the insulator 32 covers the coil mounting surface of each of the nine teeth 31B and the outer peripheral surface of the yoke 31A. The coil mounting surface is wound with the wire of a corresponding one of the nine coils 33. The outer peripheral surface of the yoke 31A is in contact with the wire of each of the nine coils 33. Therefore, the stator core 31 is insulated from the coils 33 by the insulator 32.

[0120] In this embodiment, the stator core 31 and the insulator 32 are integrally molded. The insulator 32 may be fixed to the stator core 31 by insert molding. Specifically, the stator core 31 and the insulator 32 may be formed as follows. First, the stator core 31 is placed in a mold. Next, heated and melted synthetic resin is injected into the mold. When the synthetic resin solidifies, the insulator 32 is integrated (i.e., fixed) to the stator core 31.

[0121] The nine coils 33 are respectively arranged in the nine slots 34. Specifically, the nine coils 33 are respectively provided on the nine teeth 31B. A corresponding coil 33 (more specifically, the wire constituting the coil 33) is wound around each of the nine teeth 31B. That is, each of the nine coils 33 is wound around the corresponding tooth and provided in a space including two slots 34 on both ends of the tooth (see FIG. 7). Note that, for each of the nine teeth 31B, the coil mounting surface is covered with an insulator 32, but most or all of the outer circumferential tooth surface is not covered with the insulator 32. The outer circumferential tooth surface is the surface facing radially outward (i.e., facing the magnet 23).

[0122] 2 to 5 and 8, the motor 6 includes a first fusing terminal 35U, a second fusing terminal 35V, a third fusing terminal 35W, a first tube TBu, a second tube TBv, and a third tube TBw. The first to third fusing terminals 35U, 35V, and 35W are electrically connected to nine coils 33. The first to third fusing terminals 35U, 35V, and 35W and the first to third tubes TBu, TBv, and TBw will be described in detail later with reference to FIG. 15.

[0123] [2-1-2c. Bearings] The motor 6 includes a plurality of bearings, which (i) have the rotor shaft 50 passing through them, and (ii) rotatably support the rotor shaft 50 (and thus the rotor 20).

[0124] In this embodiment, the plurality of bearings include a first bearing 54 (see FIGS. 5 and 8) and a second bearing 56 (see FIGS. 3, 5, 6, and 8). The first bearing 54 is fitted into a third support portion 41C (see FIGS. 3, 5, and 8) of the stator base 40, which will be described later. The second bearing 56 is fitted into a first support portion 41C (see FIGS. 3, 5, and 8) of the stator base 40, which will be described later. A (see Figures 3, 5, and 8).

[0125] In this embodiment, the first bearing 54 is in the form of a roller bearing (specifically a radial roller bearing, more specifically a needle roller bearing), and the second bearing 56 is in the form of a ball bearing (specifically a radial ball bearing).

[0126] 8, the rotor shaft 50 has a first surface 50A. The first surface 50A corresponds to the area of ​​the surface of the rotor shaft 50 with which the first bearing 54 contacts. The rotor shaft 50 further has a second surface 50B. The second surface 50B corresponds to the area of ​​the surface of the rotor shaft 50 with which the second bearing 56 contacts.

[0127] In this embodiment, the axial length of the first surface 50A is longer than the axial length of the second surface 50B. However, the axial length of the first surface 50A may be shorter than or equal to the axial length of the second surface 50B.

[0128] [2-1-2d. Stator base] The stator base 40 of this embodiment is made of aluminum. That is, the stator base 40 includes an aluminum alloy. In this embodiment, the stator base 40 is integrally formed of an aluminum alloy.

[0129] 3 to 5 and 8, the stator base 40 includes a support portion 41. The support portion 41 (i) has a cylindrical shape and (i) has a plurality of steps along the rotation axis AX. The rotor shaft 50 passes through the support portion 41 in the axial direction.

[0130] More specifically, the support portion 41 includes a first support portion 41A, a second support portion 41B, and a third support portion 41C, all of which have a cylindrical shape. The first support portion 41A is connected to the second support portion 41B along the rotation axis AX. The second support portion 41B is connected to the third support portion 41C along the rotation axis AX. The outer diameter of the second support portion 41B is larger than the outer diameter of the third support portion 41C. The outer diameter of the first support portion 41A is larger than the outer diameter of the second support portion 41B.

[0131] The first support portion 41A has an inner diameter large enough to fit the second bearing 56. The second support portion 41B has an outer diameter large enough to fit into the hollow portion of the insulator 32 and larger than the inner diameter of the hollow portion of the stator core 31 (more specifically, the hollow portion of the yoke 31A). The third support portion 41C has an inner diameter large enough to fit the first bearing 54 and an outer diameter large enough to be inserted into the hollow portion of the stator core 31.

[0132] 3 and 5 show a state in which the first and second bearings 54, 56 are inserted onto the rotor shaft 50. However, in reality, as will be described later, the first and second bearings 54, 56 are first fixed inside the stator base 40. Thereafter, the rotor shaft 50 is inserted into the stator base 40 and is thereby supported by the first and second bearings 54, 56.

[0133] 8, the support portion 41 is inserted into the through hole 310 of the stator core 31. More specifically, the third support portion 41C is inserted into the through hole 310. The stator core 31 is fixed to the third support portion 41C in a first fixing manner, and is thereby supported by the support portion 41 (and therefore by the stator base 40).

[0134] The first fixing mode is a mode in which the stator core 31 is fixed to the third support portion 41C, and therefore the inner circumferential surface 415 (see FIG. 11) of the third support portion 41C is not deformed. In the embodiment, in the process of inserting the stator core 31 into the third support portion 41C and fixing it to the third support portion 41C, no or little deformation of the inner surface 415 of the third support portion 41C occurs due to the insertion and / or fixing.

[0135] In this embodiment, the first fixing manner includes adhesive fixing using an adhesive 45. That is, in this embodiment, the stator core 31 is adhesively fixed to the third support portion 41C (and therefore to the stator base 40) using the adhesive 45.

[0136] The first and second bearings 54, 56 may each be fixed to the stator base 40 in any manner. In the present embodiment, the first bearing 54 is fixed to the third support portion 41C in a second fixing manner. The second fixing manner is a manner in which the third support portion 41C is (or may be) deformed due to the first bearing 54 being fixed to the third support portion 41C. That is, in the present embodiment, in the step of fitting the first bearing 54 into the third support portion 41C and fixing it to the third support portion 41C, the third support portion 41C is or may be deformed due to the fitting and / or fixation.

[0137] In this embodiment, the second fixing manner includes press-fitting, that is, the first bearing 54 is press-fitted into the third support portion 41C and thereby fixed to the third support portion 41C. In this embodiment, the second bearing 56 is also press-fitted into the first support portion 41A.

[0138] However, the first bearing 54 may be fixed to the third support portion 41C by a method other than press-fitting. For example, the first bearing 54 may be fixed to the third support portion 41C by shrink fitting, cold fitting, or other methods. The same applies to the second bearing 56.

[0139] The first bearing 54 is disposed so as to at least partially overlap in the axial direction with the stator core 31 and the rotor core 22. The second bearing 56 does not overlap in the axial direction with the stator 31 and the rotor core 22.

[0140] When assembling the motor 6, the first bearing 54 and the second bearing 56 are fixed to the stator base 40. Thereafter, the rotor shaft 50 is inserted through the first bearing 54 and the second bearing 56 in this order, and is thereby supported by the stator base 40 (more specifically, supported by the first and second bearings 54, 56). Therefore, the output shaft 51 of the motor 6 is supported by the first support portion 41A so as to be rotatable around the rotation axis AX.

[0141] As shown in FIGS. 3 to 5 and 8, the stator base 40 includes an attachment portion 42. The attachment portion 42 is integrally formed with the support portion 41. The attachment portion 42 includes an attachment portion main body 42A. The attachment portion main body 42A has a hollow disk shape. The attachment portion main body 42A is provided on the outer periphery of the first support portion 41A.

[0142] The mounting portion 42 includes a first mounting portion 42B, a second mounting portion 42C, and a third mounting portion 42D. Any one or two of the first mounting portion 42B, the second mounting portion 42C, and the third mounting portion 42D may be omitted.

[0143] The first mounting portion 42B, the second mounting portion 42C, and the third mounting portion 42D each protrude radially outward from the mounting portion main body 42A. The first mounting portion 42B, the second mounting portion 42C, and the third mounting portion 42D each have a hole SH at their tip portion. The tip portion corresponds to the end opposite the mounting portion main body 42A. A screw (not shown) is inserted into each hole SH. Each screw is threaded into a screw hole (not shown) provided on the inner surface of the housing 2, thereby fixing the mounting portion 42 (and therefore the motor 6) to the housing 2. The mounting portion 42 may be indirectly attached to the housing 2. In other words, another object may be interposed between the mounting portion 42 and the housing 2.

[0144] A substrate fixing portion 42E is provided between the first mounting portion 42B and the second mounting portion 42C. The substrate fixing portion 42E fixes the sensor substrate 60. The substrate fixing portion 42E has a shape corresponding to the shape of the sensor substrate 60, specifically, an arc shape centered on the rotation axis AX.

[0145] 3 and 5, the substrate fixing portion 42E has a first hole 43 and a first pin 43A at a first end thereof. The first pin 43A is inserted into the first hole 43. Specifically, in this embodiment, the first pin 43A is press-fitted into the first hole 43.

[0146] The substrate fixing portion 42E has a second hole 44 and a second pin 44A at its second end. The second pin 44A is inserted into the second hole 44. Specifically, in this embodiment, the second pin 44A is press-fitted into the second hole 44.

[0147] The first pin 43A is inserted into a third hole 65 in the sensor substrate 60. The second pin 44A is inserted into a fourth hole 66 in the sensor substrate 60. FIG. 2 shows the first pin 43A inserted into the third hole 65. In this embodiment, the first pin 43A and the second pin 44A are loosely fitted into the third hole 65 and the fourth hole 66, respectively. The first pin 43A and the second pin 44A position the sensor substrate 60 at a specified position relative to the stator base 40 (and therefore relative to the stator 30).

[0148] [2-1-2e. Sensor board] The sensor board 60 includes three magnetic sensors 62A, 62B, and 62C. Each of the three magnetic sensors 62A, 62B, and 62C detects a change in the magnetic field that accompanies the rotation of the rotor 20, and outputs a detection signal corresponding to the detected change (i.e., corresponding to the rotational position of the rotor 20).

[0149] The sensor board 60 is supported on the stator base 40 so that each of the three magnetic sensors 62A, 62B, and 62C faces each of the twelve magnets 23 in the axial direction. The sensor board 60 is disposed radially outward of the nine coils 33.

[0150] The sensor substrate 60 includes a connection terminal 64. The connection terminal 64 is electrically connected to each of the magnetic sensors 62A, 62B, and 62C and the controller 11. The connection terminal 64 electrically connects each of the magnetic sensors 62A, 62B, and 62C to the controller 11. The sensor substrate 60 includes the third hole 65 and fourth hole 66 described above.

[0151] [2-1-2f. Fixing the stator to the stator base] A method for fixing the stator 30 to the stator base 40 will be described in more detail with reference to Figures 11, 13, and 14. Note that, for the sake of simplicity and ease of understanding, only the stator core 31 of the stator 30 is illustrated in Figures 11, 13, and 14.

[0152] 11, in the stator base 40, the third support portion 41C has the aforementioned inner circumferential surface 415. When the first bearing 54 is press-fitted into the third support portion 41C, the outer circumferential surface 54A of the first bearing 54 is pressed against the inner circumferential surface 415 of the third support portion 41C. This fixes the first bearing 54 to the third support portion 41C.

[0153] The third support portion 41C has an outer peripheral surface 411. The outer peripheral surface 411 is in contact with the stator core 31. The stator inner peripheral surface 310B is inserted into the through-hole 310 and faces the stator inner peripheral surface 310B.

[0154] The outer peripheral surface 411 has an outer peripheral flat area 411A. The outer peripheral surface 411 is a curved surface as a whole, but the outer peripheral flat area 411A is a flat surface. The outer peripheral flat area 411A corresponds to a part of the outer peripheral surface 411.

[0155] 11 and 13, the through-hole 310 of the stator core 31 has an opening 310A. The third support portion 41C and the rotor shaft 50 protrude leftward from this opening 310A.

[0156] The through hole 310 has a stator inner peripheral surface 310B that faces the outer peripheral surface 411 of the third support portion 41C. The through hole 310 has an inner peripheral flat area 311 on the stator inner peripheral surface 310B. The third support portion 41C is inserted into the through hole 310 so that its outer peripheral flat area 411A faces the inner peripheral flat area 311 of the through hole 310 (see FIG. 14). By inserting and fixing the third support portion 41C into the through hole 310 in this manner, circumferential movement of the stator core 31 with respect to the stator base 40 is restricted.

[0157] Through-hole 310 has a plurality of recesses 315 on stator inner circumferential surface 310B. Each of the plurality of recesses 315 extends from opening 310A to a right opening along rotation axis AX on stator inner circumferential surface 310B.

[0158] In this embodiment, the through-hole 310 has five recesses 315. However, the through-hole 310 may have any number of recesses 315. The through-hole 310 may have one or more recesses 315. The through-hole 310 does not necessarily have to have any recesses 315.

[0159] 14, the motor 6 has a minute clearance 316 between the stator inner peripheral surface 310B and the outer peripheral surface 411 of the third support portion 41C. The clearance 316 includes a plurality of recesses 315. The clearance 316 is filled with an adhesive 45, which fixes the stator core 31 to the third support portion 41C.

[0160] [2-1-3. Electrical configuration of electric work equipment] The electrical configuration of the electric working machine 1 will be described in outline mainly with reference to FIG. The nine coils 33 of the motor 6 can be divided into a first-phase coil group, a second-phase coil group, and a third-phase coil group. The first-phase coil group includes a set of first-phase coils 33U1, 33U2, and 33U3 connected in parallel. The second-phase coil group includes a set of second-phase coils 33V1, 33V2, and 33V3 connected in parallel. The third-phase coil group includes a set of third-phase coils 33W1, 33W2, and 33W3 connected in parallel. The first-phase coil group, the second-phase coil group, and the third-phase coil group are delta-connected. In FIG. 15, dashed-dotted lines indicate electrical connections (more specifically, short-circuits).

[0161] From another perspective, the motor 6 can be said to have three delta connection groups. The first delta connection group includes a first-phase coil 33U1, a second-phase coil 33V1, and a third-phase coil 33W1 that are delta-connected to one another. The second delta connection group includes a first-phase coil 33U2, a second-phase coil 33V2, and a third-phase coil 33W2 that are delta-connected to one another. The third delta connection group includes a first-phase coil 33U3, a second-phase coil 33V3, and a third-phase coil 33W3 that are delta-connected to one another. The first to third delta connection groups are connected in parallel to one another.

[0162] The first ends of the first phase coils 33U1, 33U2, and 33U3 are connected to the third phase coils 33U1, 33U2, and 33U3. The second ends of the wires 33W1, 33W2, and 33W3 are connected to the first fusing terminal 35U via a first plurality of lead wires. Some of the first plurality of lead wires near the first fusing terminal 35U are bundled together and inserted into the first tube TBu.

[0163] Second ends of the first phase coils 33U1, 33U2, and 33U3 and first ends of the second phase coils 33V1, 33V2, and 33V3 are connected to the second fusing terminal 35V via second lead wires. Some of the second lead wires near the second fusing terminal 35V are bundled together and inserted into the second tube TBv.

[0164] Second ends of the second-phase coils 33V1, 33V2, and 33V3 and first ends of the third-phase coils 33W1, 33W2, and 33W3 are connected to a third fusing terminal 35W via third lead wires. Some of the third lead wires near the third fusing terminal 35W are bundled together and inserted into a third tube TBw.

[0165] The first to third fusing terminals 35U, 35V, and 35W are electrically connected to the controller 11. The nine coils 33 may be connected in any manner. For example, pairs of first phase coils 33U1, 33U2, 33U3 in the first phase coil group may be connected in series. The same applies to the second and third coil groups.

[0166] Furthermore, first phase coil 33U1, second phase coil 33V1, and third phase coil 33W1 may be star-connected, for example. The same applies to first phase coil 33U2, second phase coil 33V2, and third phase coil 33W2, and the same applies to first phase coil 33U3, second phase coil 33V3, and third phase coil 33W3.

[0167] Furthermore, the motor 6 of this embodiment has a predetermined motor resistance. Here, as shown in FIG. 15, the three electrical connection points of the first, second, and third phase coil groups, which are delta-connected to one another, are referred to as Puw, Puv, and Pvw. The motor resistance is the resistance between any two of the connection points Puw, Puv, and Pvw, or the resistance of a portion electrically equivalent to the resistance between these two connection points. Therefore, the motor resistance may be defined as the resistance between any two of the first to third fusing terminals 35U, 35V, and 35W.

[0168] In this embodiment, the motor resistance value between the connection points Puw and Puv, the motor resistance value between the connection points Puv and Pvw, and the motor resistance value between the connection points Pvw and Puw are equal.

[0169] The controller 11 receives battery power from a battery pack 12. The controller 11 includes, for example, a control circuit, a power supply circuit, and a drive circuit, none of which are shown. The drive circuit receives battery power. The drive circuit is, for example, in the form of a three-phase full-bridge circuit. That is, the drive circuit includes six semiconductor switching elements. The six semiconductor switching elements are individually controlled by control commands from a control circuit. In accordance with the control commands from the control circuit, the drive circuit converts the battery power into the motor drive power (three-phase power) described above and supplies it to the motor 6. The motor drive power is supplied to the motor 6 via first to third fusing terminals 35U, 35V, and 35W, thereby driving the motor 6.

[0170] More specifically, the drive circuit turns on any two semiconductor switching elements according to the rotational position of the motor 6, thereby causing battery power to be applied between any two of the first to third fusing terminals 35U, 35V, and 35W according to the rotational position of the motor 6. At this time, one of the two semiconductor switching elements is kept on, for example, while the other is periodically turned on and off in response to the pulse width modulation signal.

[0171] The control circuit adjusts the magnitude of the motor drive power basically by the duty ratio of the pulse width modulation signal, and also switches between two semiconductor switching elements to be turned on depending on the rotational position of the motor 6.

[0172] The control circuit includes a microcomputer. The control circuit is configured to execute various programs. The control circuit executes the various programs to realize various functions of the electric work machine 1. The functions realized by the control circuit include the function of controlling the drive circuit.

[0173] The connection terminals 64 of the sensor board 60 are connected to the controller 11 via a lead group. The lead group includes two lead wires that supply power to the three magnetic sensors 62A, 62B, and 62C, and three lead wires that transmit detection signals from each of the three magnetic sensors 62A, 62B, and 62C to the controller 11.

[0174] The control circuit detects the rotational position (i.e., electrical angle) of the rotor 20 based on the three detection signals input to the controller 11. The control circuit generates a control command based on the detected rotational position and other drive information, and outputs it to the drive circuit. As a result, motor drive power corresponding to the rotational position of the rotor 20 is supplied to the motor 6. The drive information includes, for example, the amount of operation of the trigger switch 7.

[0175] [2-1-4. Motor Features] The features of the motor 6 of this embodiment will be described in detail. [2-1-4-1. Dimension definition] First, the dimensions of each part of the motor 6 used in the following description are defined as shown in FIGS.

[0176] In FIG. 16, the rotor core outer diameter φr [mm] is the outer diameter of the rotor core 22, that is, the length in the radial direction perpendicular to the rotation axis AX. The magnet thickness Tm [mm] is the thickness of the magnet 23, that is, the length of the magnet 23 in the radial direction.

[0177] The magnet interval WM [mm] is the distance between two magnets 23 adjacent to each other in the circumferential direction. Specifically, it is the shortest distance when the rotor 20 is viewed in the direction shown in FIG. The rotor back yoke width Wrb [mm] is the thickness of the rotor core 22, that is, the length of the rotor core 22 in the radial direction.

[0178] The stator core outer diameter φs [mm] is the outer diameter of the stator core 31, that is, the length of the stator core 31 in the radial direction. The stator back yoke width Wsb [mm] is the width of the yoke 31A of the stator core 31, that is, the length of the yoke 31A in the radial direction.

[0179] The tooth width Wt [mm] is the width of the tooth 31B, specifically the length in a direction parallel to a plane perpendicular to the rotation axis AX and perpendicular to the radial direction. The slot inner diameter width Wsi [mm] is the distance between the roots of two circumferentially adjacent teeth 31B. The roots of the teeth 31B are the locations where the teeth 31B start to protrude radially from the outer periphery of the yoke 31A, in other words, the lower ends of the teeth 31B that are connected to the yoke 31A.

[0180] The slot opening width Wso [mm] is the linear distance along the circumferential direction from the radially outer opening of the slot 34. Specifically, the tooth 31B has a main body portion extending radially outward from the yoke 31A and a flange-shaped tip portion provided at the end of the main body portion. The width of the main body portion corresponds to the tooth width Wt described above. The distance between the respective tip portions of two circumferentially adjacent teeth 31B corresponds to the slot opening width Wso described above.

[0181] The tooth tip thickness Tt [mm] is the radial length of the circumferential end of the tip of the tooth 31B. 11 is the stator thickness [mm], which is the length of the stator core 31 in the axial direction (that is, the left-right direction).

[0182] The above definitions of the dimensions are merely examples, and the dimensions may be defined in any way. [2-1-4-2. Overview of motor features] The inventors of the present invention have conducted various studies in order to find a motor structure that is compact and has a desired output.

[0183] The study was based on the premise that the motor was an outer rotor type and a brushless motor. It was also assumed that the motor was an SPM type and that the permanent magnet was an Nd-Fe-B sintered magnet.

[0184] As shown in Table 1 below, we set a range of consideration for each of the various motor parameters.

[0185] [Table 1]

[0186] In Table 1, the ranges considered except for the drive voltage Vd are ranges applicable to various electric operating machines including the electric operating machine 1, and are particularly ranges that can achieve high power density. Note that power density is the motor output P per unit volume of the motor.

[0187] For example, the range for considering the rotor core outer diameter φr is set in consideration of the motor size and motor output P required for various electric operating machines. Also, for example, the range for considering the motor resistance value R is set in consideration of the required motor output P.

[0188] In the above table, "pole slot combination" refers to a combination of the number of magnetic poles and the number of slots. For example, "6P9S" indicates 6 poles and 9 slots. The slot inner diameter width Wsi [mm] is set so that two circumferentially adjacent coils do not interfere with each other (e.g., contact) even when a coil having a predetermined wire diameter (e.g., 1.1 [mm]) is used.

[0189] The slot opening width Wso [mm] is set assuming that the coil will be wound using, for example, a flyer winding method, i.e., within a range that allows the wire constituting the coil to be inserted smoothly from the slot opening into the slot with the insulator attached to the stator core.

[0190] The drive voltage Vd [V] is the battery voltage mentioned above. As mentioned above, the battery voltage of the electric operating machine 1 of this embodiment is, for example, rated at 36 [V], but for the purpose of this study, three types of drive voltage Vd shown in Table 1 were prepared. These three types of drive voltage Vd are likely to be adopted in various electric operating machines.

[0191] The motor resistance value R [mΩ] is set to a value that allows continuous operation under load, with a rotation speed of 12,000 [rpm] and a current of approximately 60 A supplied to the motor. "Under load" refers to a state in which a load is applied to the motor from an external work object via a driven tool, that is, a state in which work is actually being performed by the electric work machine. "Continuous operation" refers to operation in which the coil temperature is maintained within the rated range even in a specified high-temperature environment (e.g., 40°C).

[0192] The theoretical no-load rotation speed Nn [rpm] is the rotation speed in an ideal state where no external load is applied to the rotor. For example, in the electric work machine 1 of the above embodiment, the state in which the saw chain 10 is not in contact with the work object and is rotating freely can generally be referred to as the no-load state. However, in this no-load state, the load applied from the work object via the saw chain 10 is zero (or almost zero), but the load applied to the rotor 20 is not completely zero. Even in the no-load state, loads due to various disturbances, such as transmission loss through the power transmission unit 13 and loss due to the rotor cup 21, are applied to the rotor 20. The theoretical no-load rotation speed Nn is the rotation speed in an ideal state where no load due to such disturbances is applied.

[0193] Furthermore, when the motor rotates under ideal conditions, the induced voltage generated in the motor and the drive voltage Vd are balanced (i.e., match), and the current from the battery to the motor becomes zero. Therefore, the theoretical no-load rotation speed Nn can also be defined as the rotation speed when the current from the battery to the motor becomes zero under ideal conditions.

[0194] Here, we will provide some additional information on induced voltage. It is generally known that when a rotor with permanent magnets rotates, an induced voltage is generated in the coil on the stator side due to electromagnetic induction. Technology for detecting the rotational position of the rotor based on this induced voltage is also generally known.

[0195] In the motor 6 of this embodiment, when the rotor 20 rotates, an induced voltage is generated in each of the nine coils 33, and ultimately, as illustrated in Figure 17, an induced voltage is generated between two of the first to third fusing terminals 35U, 35V, and 35W.

[0196] 17, a predetermined electrical angle range including the electrical angle (90 degrees between U and V) at which the induced voltage between the two terminals is greatest is defined as the specified section. In this embodiment, the angle width of the specified section is 60 degrees. However, the angle width may be different from 60 degrees. Between U and V, the specified section is a section of electrical angles from 60 degrees to 120 degrees.

[0197] In this embodiment, the average value of the induced voltage within this specified interval is referred to as the effective induced voltage value E. The effective induced voltage value E indicates the substantial magnitude of the periodically changing induced voltage. The effective induced voltage value E is proportional (or nearly proportional) to the rotation speed of the motor. In other words, the effective induced voltage value E also increases linearly (or nearly linearly) as the rotation speed of the motor increases. In this embodiment, the effective induced voltage value E between any two terminals is equal.

[0198] The inventors calculated various evaluation values ​​(such as the induced voltage constant k and coefficient α described below) when various parameters were arbitrarily combined within the range of consideration shown in Table 1, and studied the optimal design of a motor that is small and capable of high output.

[0199] As a result, it was discovered that an optimal motor with high power density can be realized by further satisfying the following first to tenth conditions under the above-mentioned prerequisites. The motor 6 of this embodiment satisfies all of the first to tenth conditions. However, it may also be possible for the motor 6 to satisfy any one or more of the first to tenth conditions. (i) First condition The pole slot combination motor has 12 poles and 9 slots. (ii) Second condition The induced voltage constant k [V / krpm] must satisfy the condition 1.1≦k≦9.0.

[0200] The induced voltage constant k is calculated using the formula "k = E / N." In this formula, N [krpm] is the motor rotation speed (i.e., the rotor rotation speed). E [V] indicates the magnitude of the induced voltage generated in the motor 6 when the motor is rotating at rotation speed N. In other words, E [V] indicates the effective induced voltage value E when the motor is rotating at rotation speed N. (iii) Third condition Coefficient α [mΩ / (V / krpm) that satisfies the condition 0.2≦α≦19.0 2 ].

[0201] The coefficient α is calculated using the formula α=R / k 2 In this formula, R [mΩ] is the motor resistance value mentioned above, and k [V / krpm] is the induced voltage constant mentioned above. (iv) Fourth condition The rotor core outer diameter φr [mm] must satisfy the condition 55≦φr≦80. (v) Fifth condition The stator core outer diameter φs [mm] must satisfy the following condition: 40≦φs≦72.5. (vi) The sixth condition The rotor flatness ηr must satisfy the condition 0.1≦ηr≦0.7.

[0202] The rotor flatness ηr is calculated using the formula "ηr = Ds / φr." The meanings of Ds [mm] and φr [mm] in this formula are as described above. (vii) Seventh condition The stator flatness ηs must satisfy the condition 0.1≦ηs≦0.8.

[0203] The stator flattening ηs is calculated by the formula "ηs = Ds / φs." The meanings of Ds [mm] and φs [mm] in this formula are as described above. (viii) Eighth condition The rotor aspect ratio density ξr [ / kW] must satisfy the condition fr2≦ξr≦fr1.

[0204] The rotor aspect ratio density ξr is calculated by the formula "ξr=ηr / P." In this formula, ηr is the rotor aspect ratio described above. P [kW] is the output of the motor 6. fr1 is expressed by the following equation (1).

[0205] fr1=0.000465φr 2 -0.0782φr+3.43 (1) fr2 is expressed by the following equation (2). fr2=0.000443φr 2 -0.0698φr+2.79 (2) However, the rotor core outer diameter φr must satisfy the condition 55≦φr≦80. (ix) Ninth Condition The stator flatness density ξs [ / kW] must satisfy the condition fs2≦ξs≦fs1.

[0206] The stator flatness density ξs is calculated by the formula "ξs=ηs / P". In this formula, , ηs is the stator flatness mentioned above. P [kW] is the output power mentioned above. fs1 is expressed by the following equation (3).

[0207] fs1=0.00105φs 2 -0.144φs+5.13···(3) fs2 is expressed by the following equation (4). fs2=0.000665φs 2 -0.0887φs+3.00 (4) However, the outer diameter φs of the stator core must satisfy the condition 45≦φs≦70. (x) Tenth condition The slot opening width Wso [mm] must satisfy the condition 0.04φs≦Ws≦0.18φs.

[0208] Below, each of the first to tenth conditions will be explained in more detail. [2-1-4-2a. Regarding the first condition] For each of the multiple pole-slot combinations set within the study range, we evaluated the minimum value of the stator thickness Ds (hereinafter referred to as the "minimum stator thickness") while varying other parameters. The evaluation was conducted under the prerequisites that the motor be continuously driven with a drive voltage Vd of 36 V, a theoretical no-load rotation speed Nn of 14,000 rpm, and a motor output P of 1.5 kW. We then investigated the minimum stator thickness required for each combination of parameters other than these prerequisites. The results are shown in Figures 18 to 23.

[0209] Figure 18 shows the minimum stator thickness when the rotor core outer diameter φr = 55. In this case, the minimum stator thickness is smallest when the pole slot combination is 12 poles and 9 slots (12P9S), and the value is approximately 27 mm.

[0210] Figure 19 shows the minimum stator thickness when the rotor core outer diameter φr = 60. In this case, the minimum stator thickness is smallest when the pole slot combination is 12 poles and 9 slots (12P9S), and the value is approximately 20 mm.

[0211] Figure 20 shows the minimum stator thickness when the rotor core outer diameter φr = 65. In this case, the minimum stator thickness is smallest when the pole slot combination is 12 poles and 9 slots (12P9S), and the value is approximately 15 mm.

[0212] Figure 21 shows the minimum stator thickness when the rotor core outer diameter φr = 70. In this case, the minimum stator thickness is smallest when the pole slot combination is 12 poles and 9 slots (12P9S), and the value is approximately 12 mm.

[0213] Figure 22 shows the minimum stator thickness when the rotor core outer diameter φr = 75. In this case, the minimum stator thickness is smallest when the pole slot combination is 12 poles and 9 slots (12P9S), and the value is approximately 10 mm.

[0214] Figure 23 shows the minimum stator thickness when the rotor core outer diameter φr = 80. In this case, the minimum stator thickness is smallest when the pole slot combination is 12 poles and 9 slots (12P9S), and the value is approximately 8 mm.

[0215] 18 to 23 show only pole-slot combinations for which the minimum stator thickness is 50 mm or less for the sake of simplicity. In other words, pole-slot combinations not shown in the figures may be understood as having a minimum stator thickness exceeding 50 mm and / or having geometrically infeasible combinations of shape parameters.

[0216] 18 to 23, the pole / slot combination that resulted in the smallest minimum stator thickness was 12 poles / 9 slots for all rotor core outer diameters φr. This indicates that adopting 12 poles / 9 slots minimizes the stator thickness Ds, and therefore maximizes the possibility of downsizing the motor.

[0217] As is clear from Figures 18 to 23, in a 12-pole, 9-slot motor, the larger the rotor core outer diameter φr, the smaller the minimum value of the stator thickness Ds. Therefore, as shown in Figure 24, the larger the rotor core outer diameter φr, the smaller the overall volume of the motor can be. Note that the motor volume in Figure 24 is the value obtained by multiplying the rotor core outer diameter φr by the minimum value of the stator thickness Ds.

[0218] [2-1-4-2b. Regarding the second and third conditions] As mentioned above, it was determined that the optimal pole-slot combination that enables high power density is 12 poles and 9 slots.

[0219] Therefore, we further investigated further conditions for realizing high power density, focusing on the 12-pole, 9-slot configuration. Specifically, we investigated the induced voltage constant k and coefficient α that would enable us to achieve the target motor output P at the theoretical no-load rotation speed Nn targeted in the design. Achieving the target motor output P is synonymous with setting the motor resistance value to one of the variations of motor resistance value R shown in Table 1.

[0220] In addition, for the study, the variations of the drive voltage Vd were set to 18 [V], 36 [V], and 72 [V], and the variations of the theoretical no-load rotation speed Nn were set to 8000 [rpm], 10000 [rpm], 12000 [rpm], 14000 [rpm], and 16000 [rpm].

[0221] As a result, the study results shown in Fig. 25 were obtained. Fig. 25 shows the calculation results of the induced voltage constant k and the coefficient α when the assumed design conditions (drive voltage, theoretical no-load rotation speed, and motor resistance value) were variously changed.

[0222] 25, the minimum value of the induced voltage constant k is 1.13, and the maximum value of the induced voltage constant k is 9.00. The minimum value of the coefficient α is 0.27, and the maximum value of the coefficient α is 18.96. 25 shows that if the induced voltage constant k is designed to satisfy the condition 1.13≦k≦9.0, for example, it is possible to achieve a high power density while satisfying the desired performance. In this embodiment, taking into account a small margin, it was concluded that the required specifications can be met if the induced voltage constant k satisfies at least the condition 1.1≦k≦9.0 (i.e., the second condition).

[0223] 25 further shows that if the coefficient α is designed to satisfy the condition of 0.27≦α≦18.96, for example, it is possible to achieve a high power density while satisfying the desired performance. In this embodiment, taking into account a slight margin, it was concluded that the required specifications can be met if the coefficient α satisfies the condition of 0.2≦α≦19.0 (i.e., the third condition).

[0224] If 72V is not an acceptable driving voltage, the minimum value of the coefficient α is 0.54. Therefore, in this case, it can be said that a design in which the coefficient α satisfies the condition 0.54≦α≦18.96 can achieve a high power density while satisfying the desired performance. Therefore, in this case, the third condition may be that the coefficient α satisfies the condition 0.4≦α≦19.0, taking into account a small margin.

[0225] [2-1-4-2c. Regarding Conditions 6 and 8] Further conditions for achieving high power density in a 12-pole, 9-slot rotor were investigated. Specifically, the rotor flatness ηr was evaluated. The rotor flatness ηr is the ratio of the stator thickness Ds to the rotor core outer diameter φr.

[0226] Furthermore, the rotor aspect ratio density ξr was evaluated. The rotor aspect ratio density ξr is the ratio of the rotor aspect ratio ηr per unit motor output (1 kW in this embodiment). Here, the optimum design range of the stator thickness Ds (hereinafter referred to as the "optimum stator thickness") for each rotor core outer diameter φr shown in Figures 18 to 23 is defined as being equal to or greater than the minimum stator thickness and equal to or less than a predetermined multiple of the minimum stator thickness. The predetermined multiple can be determined as appropriate, and in this embodiment, it is set to 1.1 times.

[0227] Then, the first density ξr1 and the second density ξr2 were evaluated for each rotor core outer diameter φr. The first density ξr1 is the rotor flatness density ξr in a motor that can achieve the desired motor output P when the stator thickness Ds is the upper limit of the optimal stator thickness (i.e., 1.1 times the minimum stator thickness). The second density ξr2 is the rotor flatness density ξr in a motor that can achieve the desired motor output P when the stator thickness Ds is the minimum stator thickness. Figures 26 to 29 show the evaluation results.

[0228] Fig. 26 shows the first and second densities ξr1 and ξr2 when the continuously outputtable motor output P is 1.0 kW. In Fig. 26, when the rotor core outer diameter φr is, for example, 65 mm, the second density ξr2 is approximately 0.18 and the first density ξr1 is approximately 0.205.

[0229] Fig. 27 shows the first and second densities ξr1 and ξr2 when the continuously outputtable motor output P is 1.5 kW. In Fig. 27, when the rotor core outer diameter φr is, for example, 65 mm, the second density ξr2 is approximately 0.15 and the first density ξr1 is approximately 0.175.

[0230] Fig. 28 shows the first and second densities ξr1 and ξr2 when the continuously outputtable motor output P is 2.0 kW. In Fig. 28, when the rotor core outer diameter φr is, for example, 65 mm, the second density ξr2 is approximately 0.19 and the first density ξr1 is approximately 0.21.

[0231] Fig. 29 shows the first and second densities ξr1 and ξr2 when the continuously outputtable motor output P is 2.4 kW. In Fig. 29, when the rotor core outer diameter φr is, for example, 65 mm, the second density ξr2 is approximately 0.25 and the first density ξr1 is approximately 0.28.

[0232] It can be seen from FIGS. 26 to 29 that there are appropriate ranges for the rotor flatness ηr and rotor flatness density ξr for achieving a desired high power density. Here, the range of the appropriate rotor aspect ratio density ξr will be considered.

[0233] Among Figs. 26 to 29, the first density ξr1 is largest in Fig. 29, that is, when the output is 2.4 [kW]. Therefore, an approximation function of the first density ξr1 in Fig. 29 was calculated. Although the approximation function may be calculated in any way, in this embodiment, the first density ξr1 was approximated by a quadratic function. The approximation result is generally as shown in the following formula (5).

[0234] f(φr)=0.0004650568φr 2-0.0782156446φr+3.3960643264...(5) Therefore, based on the above formula (5), and taking into consideration some margins and other factors, the above formula (1), that is, fr1, was derived as a formula indicating the upper limit value of the rotor aspect ratio density ξr.

[0235] 26 to 29, the second density ξr2 is smallest in FIG. 27, that is, when the output is 1.5 kW. Therefore, an approximation function of the second density ξr2 in FIG. 27 was calculated. The approximation result is roughly as shown in the following formula (6).

[0236] f(φr)=0.000443φr 2 -0.0698φr+2.79 (6) Therefore, based on the above formula (6), and taking into consideration some margin and other factors, the above formula (2), that is, fr2, was derived as a formula indicating the lower limit value of the rotor aspect ratio density ξr.

[0237] From this, it was concluded that it is possible to achieve a high output density of the motor by designing the motor so that the rotor flatness density ξr satisfies the condition fr2≦ξr≦fr1 and the rotor core outer diameter φr satisfies the condition 55≦φr≦80.

[0238] 26 to 29 can also be said to show the trend of the rotor flatness ηr. Although details are omitted, the evaluation results in Fig. 26 to 29 indicate that the optimal range of the rotor flatness ηr that can achieve high power density is at least 0.1≦ηr≦0.7.

[0239] 26 to 29, the rotor flatness density ξr reaches its minimum when φr = 80 in FIG. 27 (i.e., output 1.5). At this time, ξr is approximately 0.07, so the rotor flatness ηr is approximately 0.105. Furthermore, the rotor flatness density ξr reaches its maximum when φr = 65 in FIG. 29 (i.e., output 2.4). At this time, ξr is approximately 0.275 based on r1, so the rotor flatness ηr is approximately 0.66. Therefore, it can be said that a high power density can be achieved by setting the rotor flatness ηr within the range of 0.105≦ηr≦0.66, or, with some margin, within the range of 0.1≦ηr≦0.7.

[0240] [2-1-4-2d. Conditions 7 and 9] Further conditions were investigated to achieve high power density with 12 poles and 9 slots. Specifically, the stator flatness ηs and stator flatness density ξs were evaluated in the same manner as the sixth and eighth conditions. The stator flatness ηs is the ratio of the stator thickness Ds to the stator core outer diameter φs. The stator flatness density ξs is the ratio of the stator flatness ηs per unit motor output.

[0241] FIG. 30 shows the stator aspect ratio density ξs for each stator core outer diameter φs corresponding to each rotor core outer diameter φr under the study conditions in FIG. 26. That is, on the horizontal axis of FIG. 30, "45.32" corresponds to the stator core outer diameter φs when the rotor core outer diameter φr = 55 in FIG. 26. "50.48" corresponds to the stator core outer diameter φs when the rotor core outer diameter φr = 60 in FIG. 26. "52.90" corresponds to the stator core outer diameter φs when the rotor core outer diameter φr = 65 in FIG. 26. "57.93" corresponds to the stator core outer diameter φs when the rotor core outer diameter φr = 70 in FIG. 26. "64.25" corresponds to the stator core outer diameter φs when the rotor core outer diameter φr = 75 in FIG. 26. "66.45" corresponds to the stator core outer diameter φs when the rotor core outer diameter φr=80 in FIG.

[0242] Fig. 31 shows the stator flattening density ξs for each stator core outer diameter φs corresponding to each rotor core outer diameter φr under the conditions studied in Fig. 27. The correspondence between the horizontal axis in Fig. 31 and the horizontal axis in Fig. 27 is the same as the correspondence between Fig. 30 and Fig. 26 described above. To give just one example, "50.96" on the horizontal axis in Fig. 31 corresponds to the stator core outer diameter φs when the rotor core outer diameter φr = 60 in Fig. 27.

[0243] FIG. 32 shows the stator core diameters corresponding to the rotor core outer diameters φr under the conditions of FIG. The stator flattening density ξs for each outer diameter φs is shown. The correspondence between the horizontal axis of Fig. 32 and the horizontal axis of Fig. 28 is the same as the correspondence between Fig. 30 and Fig. 26 described above. To give just one example, "54.05" on the horizontal axis of Fig. 32 corresponds to the stator core outer diameter φs when the rotor core outer diameter φr = 65 in Fig. 28.

[0244] Fig. 33 shows the stator flattening density ξs for each stator core outer diameter φs corresponding to each rotor core outer diameter φr under the conditions studied in Fig. 29. The correspondence between the horizontal axis in Fig. 33 and the horizontal axis in Fig. 29 is the same as the correspondence between Fig. 30 and Fig. 26 described above. To give just one example, "58.11" on the horizontal axis in Fig. 33 corresponds to the stator core outer diameter φs when the rotor core outer diameter φr = 70 in Fig. 29.

[0245] Fig. 30 shows the third and fourth densities ξs1 and ξs2 under the same conditions as those in Fig. 26. The third density ξs1 is the stator flatness density ξs when the stator thickness Ds is the upper limit of the optimal stator thickness (i.e., 1.1 times the minimum stator thickness), that is, the stator flatness density ξs when the rotor flatness density ξr is the first density ξr1. The fourth density ξr2 is the stator flatness density ξs when the stator thickness Ds is the minimum stator thickness, that is, the stator flatness density ξs when the rotor flatness density ξr is the second density ξr2.

[0246] In FIG. 30, when the stator core outer diameter φs is, for example, 52.90 mm, the fourth density ξs2 is approximately 0.22 and the third density ξs1 is approximately 0.25. Fig. 31 shows the third and fourth densities ξs1 and ξs2 under the same conditions as Fig. 27. In Fig. 31, when the stator core outer diameter φs is, for example, 55.35 mm, the fourth density ξs2 is approximately 0.18 and the third density ξs1 is approximately 0.2.

[0247] Fig. 32 shows the third and fourth densities ξs1 and ξs2 under the same conditions as Fig. 28. In Fig. 32, when the stator core outer diameter φs is, for example, 54.05 mm, the fourth density ξs2 is approximately 0.23 and the third density ξs1 is approximately 0.25.

[0248] Fig. 33 shows the third and fourth densities ξs1 and ξs2 under the same conditions as those in Fig. 29. In Fig. 33, when the stator core outer diameter φs is, for example, 55.49 mm, the fourth density ξs2 is approximately 0.3 and the third density ξs1 is approximately 0.325.

[0249] It can be seen from FIGS. 30 to 33 that there are appropriate ranges for the stator flatness ηs and the stator flatness density ξs to achieve a desired high power density. Therefore, the range of an appropriate stator aspect ratio density ξs is examined in the same manner as the rotor aspect ratio density ξr described above.

[0250] That is, among Figures 30 to 33, the third density ξs1 is largest in Figure 33, that is, when the output is 2.4.0 [kW]. Therefore, an approximation function of the third density ξs1 in Figure 33 was calculated. The approximation result is roughly as shown in the following formula (7).

[0251] f(φs)=0.0010506320φs 2 -0.1440682961φs+5.0766542983...(7) Therefore, based on the above formula (7), and taking into consideration some margins and other factors, the above formula (3), that is, fs1, was derived as a formula indicating the upper limit of the stator flattening density ξs.

[0252] 30 to 33, the fourth density ξs2 is smallest in FIG. 31, that is, when the output is 1.5 kW. Therefore, an approximation function of the fourth density ξs2 in FIG. 31 was calculated. The approximation result is roughly as shown in the following formula (8).

[0253] f(φs)=0.0006647086φs 2 -0.0886633681φs+3.0478633565...(8) Therefore, based on the above formula (8), and taking into consideration some margins and other factors, the above formula (4), that is, fs2, was derived as a formula indicating the lower limit value of the stator flattening density ξs.

[0254] From this, it was deduced that a high power density of the motor can be achieved by designing the motor so that the stator flattening density ξs satisfies the condition fs2≦ξs≦fs1 and the stator core outer diameter φs satisfies the condition 45≦φs≦70. The range of the stator core outer diameter φs was determined based on the fact that the stator core outer diameter φs is distributed within the range of approximately 45 to 70 in Figures 30 and 31.

[0255] 30 to 33 also show the tendency of the stator flattening ηs. Although details are omitted, the evaluation results in Fig. 30 to 33 indicate that the optimum range of the stator flattening ηs that can achieve high power density is at least 0.1≦ηs≦0.8.

[0256] 30 to 33, the stator flattening density ξs reaches its minimum value when φs = 67.16 in FIG. 31 (i.e., output 1.5). At this time, ξs is approximately 0.08, so the stator flattening ηs is approximately 0.12. Also, the stator flattening density ξs reaches its maximum value when φs = 45.32 in FIG. 30 (i.e., output 1.0). At this time, ξs is approximately 0.52, so the stator flattening ηs is approximately 0.52. Therefore, it can be said that a high output density can be achieved by setting the stator flattening ηs within the range of 0.12≦ηs≦0.52, or, taking into account a small margin, within the range of 0.1≦ηs≦0.8.

[0257] [2-1-4-2e. Regarding conditions 4, 5, and 10] The reasons for the fourth, fifth, and tenth conditions are the same as those for setting the ranges for consideration in Table 1. In other words, by keeping the rotor core outer diameter φr within the range of 55≦φr≦80, keeping the stator core outer diameter φs within the range of 40≦φs≦72.5, and / or keeping the slot opening width Wso within the range of 0.04φs≦Ws≦0.18φs, it is possible to realize a motor that satisfies the desired design requirements (including high power density) while still maintaining the above-mentioned prerequisites.

[0258] [Additional information on the effectiveness of the 12-pole, 9-slot system] Here is some additional explanation about the effectiveness of the 12-pole, 9-slot configuration. By adopting a 12-pole, 9-slot configuration, not only can the motor be made more compact and have a higher power density, but it can also be made lighter. In other words, of the various pole-slot combinations listed in the range of consideration in Table 1, the 12-pole, 9-slot configuration can make the motor the lightest.

[0259] FIG. 34 shows a rough outline of the relationship between the volume and mass of the motor for the various combinations described above based on the ranges considered in Table 1. Only 12 poles and 9 slots, 14 poles and 12 slots, and 8 poles and 6 slots are shown in Figure 34. This means that the characteristics of pole-slot combinations other than these are outside the range of the graph in Figure 34.

[0260] Therefore, among the multiple pole / slot combinations, 12 poles and 9 slots, 14 poles and 12 slots, and 8 poles and 6 slots can reduce the volume and mass under the above prerequisites.

[0261] In particular, the 12-pole, 9-slot design can minimize the volume and mass. With 12 poles and 9 slots, a motor with a minimum volume of Vo1 and mass of M1 can be realized. With 14 poles and 12 slots, a minimum volume larger than Vo1 (at least Vo2) is required to provide equivalent performance. With 8 poles and 6 slots, a volume even larger than Vo2 is required to provide equivalent performance, and the mass will also be greater than M1.

[0262] [2-2. Second embodiment] The second embodiment illustrates another form of rotor. As shown in Fig. 35, the rotor 110 of the second embodiment has a different form of magnet compared to the rotor 20 of the first embodiment. The rotor 110 of the second embodiment includes 12 magnets 113 (specifically, 12 sets or 12 groups). The magnets 113 are permanent magnets.

[0263] The magnet 113 is divided into multiple parts in the circumferential direction. In the second embodiment, the magnet 113 is divided into two parts in the circumferential direction. Specifically, the magnet 113 includes a first part 113A and a second part 113B. The second part 113B is separate from the first part 113A.

[0264] Magnet 113 can be considered as magnet 23 of the first embodiment divided into two halves. In fact, the magnetic properties of magnet 113 are equivalent to magnet 23 of the first embodiment divided into two halves. Note that first portion 113A and second portion 113B may be in contact with each other or may be spaced apart.

[0265] The shape and size of the first portion 113A are the same as the shape and size of the second portion 113B. However, the first portion 113A and the second portion 113B may have different shapes and / or sizes. Furthermore, the magnet 113 may be divided into three or more portions in the circumferential direction.

[0266] In this way, by dividing the magnet 113 into a plurality of pieces, the loss (for example, eddy current loss) occurring in the magnet 113 can be reduced more than in the magnet 23 of the first embodiment. [2-3. Third embodiment] The third embodiment illustrates yet another form of rotor. As shown in Fig. 36, the rotor 120 of the third embodiment has a different form of magnet compared to the rotor 20 of the first embodiment. The rotor 120 of the third embodiment includes 12 magnets 123 (specifically, 12 sets or 12 groups). The magnets 123 are permanent magnets.

[0267] The magnet 123 is divided into multiple parts in the axial direction. In the third embodiment, the magnet 123 is divided into two parts in the axial direction. Specifically, the magnet 123 includes a first part 123A and a second part 123B. The second part 123B is separate from the first part 123A.

[0268] Magnet 123 can be considered as magnet 23 of the first embodiment divided into two parts. In fact, the magnetic properties of magnet 123 are equivalent to magnet 23 of the first embodiment divided into two parts. Note that first portion 123A and second portion 123B may be in contact with each other or may be spaced apart.

[0269] The shape and size of the first portion 123A are the same as the shape and size of the second portion 123B. However, the first portion 123A and the second portion 123B may have different shapes and / or sizes. Furthermore, the magnet 123 may be divided into three or more portions in the axial direction.

[0270] In this way, by dividing the magnet 123 into a plurality of pieces, similar to the second embodiment, the loss (for example, eddy current loss) occurring in the magnet 123 can be reduced more than that of the magnet 23 of the first embodiment.

[0271] [2-4. Other embodiments] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0272] (1) In the above embodiment, the electric working machine 1 is in the form of an electric chainsaw. However, the electric working machine 1 may be in a form other than an electric chainsaw. Specifically, the electric working machine 1 may be in the form of any of the various types of equipment described above that are configured to be used at work sites such as construction, manufacturing, gardening, and civil engineering.

[0273] (2) The electric operating machine 1 may be configured to be able to be driven by receiving AC power from an AC power source instead of or in addition to the battery pack 12. [2-5. Supplementary Information] In the above embodiments, multiple functions achieved by one component may be achieved by multiple components, and one function achieved by one component may be achieved by multiple components. Furthermore, multiple functions achieved by multiple components may be achieved by one component, and one function achieved by multiple components may be achieved by one component. Furthermore, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of one of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Explanation of symbols]

[0274] 1...electric work machine, 5...battery mounting section, 6...motor, 10...saw chain, 11...controller, 12...battery pack, 13...power transmission section, 20, 110, 120...rotor, 21...rotor cup, 22...rotor core, 23, 113, 123...magnet, 30...stator, 31...stator core, 31A...yoke, 31B...teeth, 33...coil, 34...slot, 50...rotor shaft

Claims

1. an outer rotor type brushless motor; a power transmission unit configured to transmit a rotational force of the brushless motor to a driven tool to drive the driven tool; Equipped with The brushless motor is a rotor having a cylindrical rotor core and twelve magnetic poles spaced apart from one another along a circumferential direction of the rotor core, the rotor core having a plurality of first core plates stacked on top of one another; a stator including a stator core disposed on an inner circumferential side of the rotor core and having nine teeth, and nine coils wound around the nine teeth, respectively, the stator core including a plurality of second core plates stacked on top of each other; An electric work machine equipped with:

2. The electric operating machine according to claim 1, The brushless motor is 1.1≦k≦9.0, The induced voltage constant k [V / krpm] satisfies the condition The induced voltage constant k is calculated by the formula E / N, where: N [krpm] is the rotation speed of the brushless motor, E [V] is a value indicating the magnitude of the induced voltage generated in the brushless motor when the brushless motor is rotating at the rotation speed N. Electric work equipment.

3. The electric operating machine according to claim 1 or 2, The brushless motor is ０．２≦α≦１９．０、 Coefficient α [mΩ / (V / krpm) ２ ], The coefficient α is expressed by the formula R / k ２ In this formula, R [mΩ] is a motor resistance value based on the resistance value of at least one of the nine coils, k [V / krpm] is calculated by the formula E / N, where N [krpm] is the rotation speed of the brushless motor, and E [V] is a value indicating the magnitude of the induced voltage generated in the brushless motor when the brushless motor is rotating at the rotation speed N. Electric work equipment.

4. The electric operating machine according to any one of claims 1 to 3, The rotor core is 55≦φr≦80, The rotor core has an outer diameter φr [mm] that satisfies the condition The rotor core outer diameter φr is the outer diameter of the rotor core. Electric work equipment.

5. The electric operating machine according to any one of claims 1 to 4, The stator core is 40≦φs≦72.5, The stator core has an outer diameter φs [mm] that satisfies the condition The stator core outer diameter φs is the outer diameter of the stator core, Electric work equipment.

6. An electric operating machine according to any one of claims 1 to 5, The brushless motor is 0.1≦ηr≦0.7, The rotor has a flatness ηr that satisfies the condition The rotor flatness ηr is calculated by the formula Ds / φr, where Ds [mm] is the length of the stator core in the axial direction, the axial direction being parallel to the rotation axis of the rotor, φr [mm] is the outer diameter of the rotor core, Electric work equipment.

7. The electric operating machine according to any one of claims 1 to 6, The brushless motor is 0.1≦ηs≦0.8, The stator has an oblateness ηs that satisfies the condition The stator flatness ηs is calculated by the formula Ds / φs, where Ds [mm] is the length of the stator core in the axial direction, the axial direction being parallel to the rotation axis of the rotor, φs [mm] is the outer diameter of the stator core, Electric work equipment.

8. An electric operating machine according to any one of claims 1 to 7, The brushless motor is fr2≦ξr≦fr1 The rotor has a flattening density ξr [ / kW] that satisfies the condition The rotor flatness density ξr is calculated by the formula ηr / P, where ηr is calculated by the formula Ds / φr, where: Ds [mm] is the length of the stator core in the axial direction, the axial direction being parallel to the rotation axis of the rotor, φr [mm] is the outer diameter of the rotor core, and satisfies 55≦φr≦80, P [kW] is the output of the brushless motor, The fr1 and fr2 are represented by the following two formulas: fr1=0.000465φr ２ -0.0782φr+3.43 fr2=0.000443φr ２ -0.0698φr+2.79 Meet the electric work machine.

9. An electric operating machine according to any one of claims 1 to 8, The brushless motor is fs2≦ξs≦fs1 The stator has a flattening density ξs [ / kW] that satisfies the condition The stator flattening density ξs is calculated by the formula ηs / P, where ηs is calculated by the formula Ds / φs, where: Ds [mm] is the length of the stator core in the axial direction, the axial direction being parallel to the rotation axis of the rotor, φs [mm] is the outer diameter of the stator core, and satisfies 45≦φs≦70, P [kW] is the output of the brushless motor, The fs1 and fs2 are expressed by the following two equations: fs1=0.00105φs ２ -0.144φs+5.13 fs2=0.000665φs ２ -0.0887φs+3.00 Meet the electric work machine.

10. An electric operating machine according to any one of claims 1 to 9, The rotor core includes 12 magnet portions, The twelve magnet portions (i) are arranged spaced apart from one another along the rotation direction of the rotor core, (ii) each have one or more permanent magnets, and (iii) each form a corresponding one of the twelve magnetic poles. Electric work equipment.

11. The electric operating machine according to claim 10, the one or more permanent magnets include sintered magnets comprising neodymium, iron, and boron; Electric work equipment.

12. The electric operating machine according to claim 10 or 11, The twelve magnet portions are attached to an inner circumferential surface of the rotor core. Electric work equipment.

13. The electric operating machine according to any one of claims 10 to 12, An electric working machine, wherein each of the twelve magnet units includes two or more permanent magnets that are independent of each other.

14. The electric operating machine according to claim 13, An electric working machine, wherein in each of the 12 magnet sections, the two or more permanent magnets are arranged along a radial direction of the rotor core.

15. The electric operating machine according to claim 13, An electric working machine, wherein in each of the 12 magnet sections, the two or more permanent magnets are arranged along the rotation axis of the rotor core.

16. An electric operating machine according to any one of claims 1 to 15, The nine coils are delta-connected to one another.

17. The electric operating machine according to claim 16, the stator includes a first coil group, a second coil group, and a third coil group that are delta-connected to one another; the first coil group includes three coils among the nine coils that are connected in parallel to each other, the second coil group includes three coils of the nine coils that are different from the first coil group and are connected in parallel to each other, the third coil group includes three coils among the nine coils that are different from either the first coil group or the second coil group and are connected in parallel to each other; Electric work equipment.

18. An electric operating machine according to any one of claims 1 to 17, The stator core is 0.04φs≦Ws≦0.18φs, The slot opening width Wso [mm] satisfies The slot opening width Wso is a linear distance along the circumferential direction of an opening on the radially outer side between two circumferentially adjacent teeth among the nine teeth. Electric work equipment.

19. An electric operating machine according to any one of claims 1 to 18, moreover, a grip configured to be gripped by a user of the electric working machine, and / or a battery mounting portion configured to detachably mount a battery pack including a battery; An electric work machine equipped with:

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