CN110401306B

CN110401306B - Electric working machine

Info

Publication number: CN110401306B
Application number: CN201910217361.4A
Authority: CN
Inventors: 中野富士雄; 镰田真贵
Original assignee: Makita Corp
Current assignee: Makita Corp
Priority date: 2018-04-24
Filing date: 2019-03-21
Publication date: 2023-02-21
Anticipated expiration: 2039-03-21
Also published as: JP7017461B2; JP2019193415A; CN110401306A; DE102019109403A1

Abstract

The invention provides an electric working machine having a motor, which can inhibit the increase of the number of components and reduce the negative effect on other electric equipment around the electric working machine when the electric noise of the motor is generated. One aspect of the present disclosure is an electric working machine including a motor, an operating portion, a pair of current-carrying wirings, a ground connection wiring, and a ground metal portion. The ground connection wiring is electrically connected to one of the pair of brush portions. The ground metal part is electrically connected to the ground connection wiring and has a larger volume than the brush part. In this electric working machine, even when a spark is generated between the commutator and the brush portion in the motor, since the electric noise due to the spark is absorbed by the ground metal portion via the ground connection wiring, it is possible to reduce the propagation of the electric noise to the current-carrying wiring and to suppress the noise from being radiated from the current-carrying wiring to the outside.

Description

Electric working machine

Technical Field

The present disclosure relates to an electric working machine including a motor.

Background

A motor used as a power source in an electric working machine may generate electrical noise when the motor is driven. Specifically, when the motor is driven, sparks are generated when the brush comes into contact with and separates from the commutator, and electrical noise may be generated. When such electrical noise is generated, adverse effects may occur on other electrical devices present in the periphery of the electric working machine.

In contrast, an electric working machine provided with a noise suppression circuit for noise reduction (noise reduction) has been proposed (patent document 1). The noise suppression circuit includes, for example, a choke coil for connecting the pair of input terminals and the motor terminal, and a capacitor for connecting the pair of input terminals and the ground terminal, respectively, as a noise suppression element.

Patent document 1: japanese Kokai publication Hei-8-196

However, the electric working machine described above needs to be provided with a noise suppression circuit when suppressing the electric noise generated in the motor, and therefore the number of components of the electric working machine increases. Due to such an increase in the number of components, the overall cost of the electric working machine increases.

Disclosure of Invention

Therefore, in one aspect of the present disclosure, it is desirable to provide an electric working machine having a motor, which is capable of suppressing an increase in the number of components and reducing adverse effects on other electric devices present around the electric working machine when electric noise of the motor is generated.

One aspect of the present disclosure is an electric working machine including a motor, an operating portion, a pair of current-carrying wirings, a ground connection wiring, and a ground metal portion.

The motor has a rotor that is rotated by supply of driving electric power from the outside. The working part transmits the rotating force of the rotor to work. A pair of current-carrying wirings supply the driving electric power to the motor.

The motor includes a commutator, a pair of brush portions, and a stator.

The commutator rotates together with the rotor. The pair of brush portions is electrically connected to the pair of current-carrying wirings. In addition, the pair of brush portions repeats electrical connection and disconnection with and from the commutator with rotation of the rotor. The stator includes a yoke (magnetic yoke) disposed outside the rotor.

The ground connection wiring is electrically connected to one of the pair of brush portions. The grounding metal part is electrically connected with the grounding connection wiring. The grounding metal part is larger in volume than the brush part.

In this electric working machine, one of the pair of brush portions is connected to the ground metal portion via the ground connection wiring, so even when a spark is generated between the commutator and the brush portion in the motor, electrical noise due to the spark is absorbed by the ground metal portion via the ground connection wiring. In other words, even when a spark is generated between the commutator and the brush portion, the electric working machine can reduce the propagation of electrical noise to the current-carrying wiring and can suppress the emission of noise from the current-carrying wiring to the outside.

Thus, according to the electric working machine, it is possible to suppress an increase in the number of components such as the capacitor and reduce adverse effects on other electric devices present around the electric working machine when electrical noise of the motor is generated.

In the electric working machine described above, the metal part may be a yoke of the stator. Since the yoke of the stator is a member having a larger volume than the brush portion, it can sufficiently absorb the electrical noise caused by the spark.

In the above-described electric working machine, the working portion may be made of metal, and the metal portion may be the working portion. The working portion is a member having a larger volume than the brush portion, and therefore, the electric noise due to the spark can be sufficiently absorbed.

In the electric working machine, the brush portion may include a brush body portion and a brush holding portion, and the ground connection wiring may be connected to at least one of the brush body portion and the brush holding portion.

The brush body portion is electrically connected to the commutator, and is formed using at least a conductive carbon material. The brush holding portion is a member that holds the brush body portion in a slidable state, and is formed using at least a conductive metal material.

In the brush portion having such a configuration, even when the distance from the commutator changes, the brush main body portion slides, and thus the connection state with the commutator can be maintained. Further, since the ground connection wiring is connected to at least one of the brush body portion and the brush holding portion, it is possible to establish electrical connection between the ground connection wiring and the brush portion, and also to establish electrical connection between the brush portion and the ground metal portion.

Thus, according to the electric working machine, even when the distance between the brush portion and the commutator changes, the electric connection between the brush portion and the grounding metal portion can be established, and therefore, the adverse effect on other electric devices due to the electric noise of the motor can be reduced.

The brush body portion may be formed using a conductive carbon material or a conductive metal material.

Next, in the electric working machine described above in which the brush portion includes the brush main body portion and the brush holding portion, the ground connection wiring may be connected to the brush main body portion.

In the electric working machine described above in which the brush portion includes the brush main body portion and the brush holding portion, the ground connection wiring may be connected to the brush holding portion.

Next, in the electric working machine, the pair of current-carrying wirings may be directly connected to the pair of brush portions, and the ground connection wiring may be connected to one of the pair of current-carrying wirings at the same position as the brush portion.

In this way, by adopting the configuration in which the grounding connection wiring and the conducting wiring are connected to the brush portion at the same position, the work of connecting the grounding connection wiring and the brush portion and the work of connecting the conducting wiring and the brush portion can be performed in one operation. For example, when the connection work is performed by soldering, the end portion of the current-carrying wiring and the end portion of the ground connection wiring may be collectively soldered to the brush portion.

Thus, according to the electric working machine, the connection work at the time of manufacturing can be simplified, and therefore, the manufacturing cost can be reduced.

Next, in the electric working machine, the pair of current-carrying wirings may be directly connected to the pair of brush portions, and the ground connection wiring may be connected to the brush portions at a position different from a connecting portion between the pair of current-carrying wirings and the pair of brush portions.

In this way, by making the connection portion of the brush portion with the ground connection wiring and the connection portion of the brush portion with the conduction wiring different in position, the degree of freedom in determining the route for laying the ground connection wiring is improved. Thus, interference between the ground connection wiring and the current-carrying wiring is suppressed, and the ground connection wiring and the brush portion can be reliably connected.

Thus, according to the electric working machine, the ground connection wiring and the brush portion can be reliably connected, and the electric connection between the brush portion and the ground metal portion can be established, so that the adverse effect of the electric noise caused by the motor on other electric devices can be reduced.

In the case where the brush portion includes the brush main body portion and the brush holding portion, the brush main body portion may be connected to the ground connection wiring and the brush holding portion may be connected to the current-carrying wiring. In the case where the brush portion includes the brush body portion and the brush holding portion, both the ground connection wiring and the current-carrying wiring may be connected to the brush holding portion, and a connection portion of the brush holding portion to the ground connection wiring and a connection portion of the brush holding portion to the current-carrying wiring may be located at different positions. In addition, when the brush portion includes the brush body portion and the brush holding portion, both the ground connection wiring and the current-carrying wiring may be connected to the brush body portion, and a connection portion of the brush body portion to the ground connection wiring and a connection portion of the brush body portion to the current-carrying wiring may be different in position.

Drawings

Fig. 1 is a perspective view showing an external appearance of a circular saw according to a first embodiment.

Fig. 2 is a cross-sectional view schematically showing an internal configuration of the circular saw according to the first embodiment.

Fig. 3 is an exploded perspective view of a brush including a brush body portion and a brush holding portion.

Fig. 4 is an explanatory view showing a state of a side of the main body case accommodating the motor, which is coupled to the blade case.

Fig. 5 is an explanatory diagram showing an electrical connection configuration between the motor and the control device in the first embodiment.

Fig. 6 is an explanatory diagram showing an electrical connection configuration between the motor and the control device in the comparative example.

Fig. 7 shows the measurement result of noise in the first embodiment.

Fig. 8 shows the measurement result of noise in the comparative example.

Fig. 9 is an explanatory diagram showing an electrical connection configuration between a motor and a control device in another embodiment.

Fig. 10 is an exploded perspective view of a brush having a structure in which both the ground connection wiring and the current supply wiring are welded to the brush holding portion.

Fig. 11 is an exploded perspective view of a brush having a configuration in which a connection portion between a brush body portion and a ground connection wiring and a connection portion between the brush body portion and an energizing wiring are different in position.

Fig. 12 is a cross-sectional view schematically showing an internal configuration of a circular saw according to another embodiment.

Detailed Description

Hereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings.

The present disclosure is not limited to the following embodiments, and various embodiments can be adopted as long as they fall within the technical scope of the present disclosure.

[1. First embodiment ]

[1-1. Overall constitution ]

A first embodiment will be described with reference to a circular saw 1 (hereinafter, also referred to as a circular saw 1) which is one of electric working machines used for cutting an object.

As shown in fig. 1 and 2, the circular saw 1 includes a main body case 10 and a blade case 20.

As shown in fig. 2, the main body case 10 houses the motor 2 as a driving force source. A blade housing 20 is formed to cover a portion of the saw blade 16. The blade housing 20 houses the gear mechanism 12 that transmits the rotation of the motor 2 to the saw blade 16.

The main body case 10 includes a handle portion 8 for a user to hold. The handle portion 8 is formed to protrude in a direction orthogonal to the rotation shaft 4 of the motor 2.

The rotary shaft 4 of the motor 2 is rotatably fixed by a bearing 41 provided in the main body case 10 and a bearing 43 provided in the blade case 20. A fan 6 that generates cooling air by rotation is provided on the rotating shaft of the motor 2.

An output shaft 14 for fixing a circular saw blade 16 is provided inside the blade housing 20. The output shaft 14 is rotatably supported inside the blade housing 20 via a bearing 24 and a support member 24 a.

The saw blade 16 is fixed to an end of the output shaft 14 using the bolt 18 and the

clamping members

19A and 19B. The clamping

members

19A and 19B are formed in a ring shape having a through hole at the center. The clamping

members

19A, 19B are configured to clamp the saw blade 16. The bolt 18 is inserted into a through hole in the center of each of the clamp member 19A, the saw blade 16, and the clamp member 19B, and is screwed into a screw hole provided at an end of the output shaft 14. The output shaft 14 includes a flange portion 36 at a position where the saw blade 16 is fixed. In other words, the saw blade 16 is clamped between the bolt 18 and the flange portion 36 together with the

clamping members

19A, 19B, and is fixed to the end portion of the output shaft 14.

The support member 24a rotatably supports the output shaft 14 via a bearing 24. The support member 24a is fixed to the blade housing 20 such that the central axis of the output shaft 14 is parallel to the central axis of the rotary shaft 4 of the motor 2.

Inside the blade case 20, the output shaft 14 and the rotating shaft 4 of the motor 2 are coupled via a gear mechanism 12 for speed reduction. By this connection, the output shaft 14 is rotationally driven by the motor 2 via the gear mechanism 12, and the saw blade 16 is rotated.

The blade housing 20 is formed to cover approximately half of the outer circumference of the saw blade 16 fixed to the output shaft 14. A cover 26 for covering a part of the outer periphery of the saw blade 16 not covered by the blade housing 20 is coupled to the blade housing 20. The cover 26 is fixed to the blade housing 20 so as to be rotatable about the output shaft 14. The blade housing 20 and the cover 26 are configured to cover substantially the entire outer periphery of the saw blade 16.

The cover 26 is normally held in a protective position covering substantially the entire outer periphery of the saw blade 16 by the urging force of a pressing member (not shown). When the circular saw 1 is used, the cover 26 is rotated against the urging force of the urging member, and a part of the outer periphery of the saw blade 16 is exposed. In this manner, the user can cut the workpiece by rotating the cover 26 to expose a part of the outer periphery of the saw blade 16, and moving the circular saw 1 in the cutting direction (see fig. 1) to bring the rotating saw blade 16 into contact with the workpiece. The cover 26 is movable from the protection position to the retracted position about the output shaft 14. The retracted position of the cover 26 is a position at which an area of the outer periphery of the saw blade 16 not covered by the blade case 20 is exposed.

[1-2. Motor ]

Next, the motor 2 will be explained.

The motor 2 is a commutator motor (so-called brush motor) configured to switch the current flowing through the armature according to the rotation phase and maintain the rotation torque in a constant direction.

As shown in fig. 2, the motor 2 includes a rotor 9, a mechanical commutator 11 (hereinafter, also simply referred to as the commutator 11), a pair of brushes 13, and a stator 17.

The rotor 9 is formed integrally with the rotating shaft 4 and the commutator 11, and includes a winding (not shown) electrically connected to the commutator 11. The motor 2 of the present embodiment includes a rotor 9 as an armature.

A commutator 11 is provided at an end of the rotor 9, and rotates together with the rotor 9. The commutator 11 is configured to perform energization of the winding of the rotor 9 when electrically connected to the pair of brushes 13, and to stop energization of the winding of the rotor 9 when electrically disconnected from the pair of brushes 13. Since the commutator 11 can have a known configuration, a detailed description thereof will be omitted.

The pair of brushes 13 is fixed inside the main body case 10 such that one brush 13 is arranged at a different circumferential position from the other brush 13 in a circumferential direction around the commutator 11. Although only one brush 13 is shown in fig. 2, the motor 2 includes another brush 13 not shown.

The commutator 11 and the pair of brushes 13 have a connection position where they are electrically connected to each other and a disconnection position where they are not electrically connected to each other, depending on the rotational position of the rotor 9. Therefore, the pair of brushes 13 repeats an electrically connected state to the commutator 11 and an electrically disconnected state from the commutator 11 with the rotation of the rotor 9.

As shown in fig. 3, the brush 13 includes a brush body portion 13a and a brush holding portion 13b. The brush body portion 13a and the brush holding portion 13b are both made of a conductive material. The conductive material of the brush main body portion 13a is composed of a conductive carbon material and a conductive metal material (e.g., brass). The conductive material is composed of a conductive carbon material as a main component and a conductive metal material. Here, the "main component" refers to a component that is contained in the largest amount among the components constituting the conductive material. The conductive material of the brush holding portion 13b is made of a conductive metal material (e.g., brass).

The brush body portion 13a includes a contact portion 13a1, a connection portion 13a2, and an elastic portion 13a3. The contact portion 13a1 is configured to have a shape similar to a polygonal prism including a curved surface 13a1a for contacting the commutator 11. The coupling portion 13a2 is configured to be connectable to an end portion of the brush holding portion 13b. The elastic portion 13a3 is a so-called coil spring, and has one end fixed to the contact portion 13a1 and the other end fixed to the coupling portion 13a2.

The brush holding portion 13b is formed in a cylindrical shape with both ends open. The brush holding portion 13b has an opening portion with a cross-sectional shape that can be inserted into the contact portion 13a1. The brush holding portion 13b is configured such that the contact portion 13a1 can be inserted (moved) into the brush holding portion 13b from one open end to the other open end. In other words, the brush holding portion 13b is a member that slidably holds the brush body portion 13a (particularly, the contact portion 13a 1).

The brush body portion 13a is configured such that the coupling portion 13a2 can be connected to an end portion of the brush holding portion 13b in a state where the contact portion 13a1 is inserted into the brush holding portion 13b. At this time, the contact portion 13a1 is disposed in a slidable (movable) state inside the brush holding portion 13b.

The brush holding portion 13b is integrally formed with the insulating member 25 in a state in which the cylindrical central portion is surrounded by the insulating member 25. The insulating member 25 is made of an insulating material (e.g., resin). The brush holding portion 13b is fixed inside the main body case 10 via an insulating member 25.

The brush 13 is fixed inside the main body case 10 via the insulating member 25 in a state where the brush body portion 13a and the brush holding portion 13b are integrally provided, and thereby the contact portion 13a1 is brought into contact with the commutator 11. At this time, the abutting portion 13a1 is pressed against the commutator 11 by the elastic force of the elastic portion 13a3. In other words, the brush body portion 13a (particularly, the abutting portion 13a 1) is a member electrically connected to the commutator 11.

Returning to fig. 2, the stator 17 includes a yoke 17a (hereinafter also referred to as a yoke 17 a) and a pair of permanent magnets 17b.

The yoke 17a is formed in a cylindrical shape and is disposed outside the rotor 9. The yoke 17a is formed of a metal material (e.g., iron, silicon steel plate, etc.). The pair of permanent magnets 17b are fixed to the inner surface of the yoke 17a so as to be disposed at positions sandwiching the rotor 9. Thus, the yoke 17a and the pair of permanent magnets 17b are disposed outside the rotor 9.

Fig. 4 shows a state of the side of the main body case 10 in which the motor 2 is housed, which is coupled to the blade case 20.

As shown in fig. 4, the stator 17 (specifically, the yoke 17 a) is fixed to the main body case 10 by two fixing screws 33. In fig. 4, the arrangement region of the stator 17 is shown by diagonal lines.

As shown in fig. 2, the fixing screw 33 includes a screw head portion 33a and a screw shaft portion 33b. The fixing screw 33 is screwed to the main body case 10 with the screw shaft portion 33b inserted into the annular washer 35. At this time, the yoke 17a is sandwiched between the screw head 33a and the main body housing 10 via the annular spacer 35, and the stator 17 is fixed to the main body housing 10.

In the cross-sectional view of fig. 2, the portions indicated by the areas A1 and A2 in the main body case 10 show the internal configuration of the portion corresponding to the cross-sectional position indicated by the line P0-P1 in fig. 4. In the cross-sectional view of fig. 2, the portions indicated by the areas A1 and A3 in the main body case 10 show the internal configuration of the portion corresponding to the cross-sectional position indicated by the line P0-P2 in fig. 4.

One brush 13 of the pair of brushes 13 is electrically connected to the ground connection wiring 21. Specifically, the brush body 13a of the brush 13 is connected to an end of the ground connection wiring 21. The ground connection wiring 21 can be formed using a lead wire or the like formed by covering a flexible conductive material with an insulating coating layer. As a method of connecting the brush 13 and the ground connection wiring 21, soldering, welding, or the like can be used. In the present embodiment, as shown in fig. 3, an end portion of the ground connection wiring 21 is welded to the contact portion 13a1 in the brush main body portion 13 a.

The other end of the ground connection wiring 21 is connected to the annular spacer 35 and electrically connected to the yoke 17a of the stator 17. Thus, the brush 13 is electrically connected to the stator 17 via the ground connection wiring 21 and the annular spacer 35.

[1-3. Electric constitution ]

Next, an electrical configuration of the circular saw 1 centering on a current path to the motor 2 will be described.

The circular saw 1 includes a control device 52 for controlling the state of energization to the motor 2.

As shown in fig. 5, the control device 52 includes a positive output terminal 52a and a negative output terminal 52b. The control device 52 is connected to the motor 2 via two current-carrying wires 23. Specifically, one brush 13 of the pair of brushes 13 provided in the motor 2 is connected to the positive output terminal 52a via one conducting wire 23, and the other brush 13 of the pair of brushes 13 is connected to the negative output terminal 52b via the other conducting wire 23.

The circular saw 1 includes an operation switch 37 (trigger switch 37) (see fig. 1), a battery pack 39 (see fig. 1), and a voltage conversion circuit (not shown). The voltage conversion circuit converts a voltage value of the dc voltage supplied via the battery pack 39 to generate a dc voltage for driving the motor. The control device 52 detects an operation amount of the operation switch 37 by the user, and energizes the motor 2 with a dc voltage corresponding to the operation amount. Then, the control device 52 energizes the motor 2 through the energizing wire 23, and the motor 2 rotates in accordance with the operation amount of the user.

Here, as shown in fig. 5, the pair of brushes 13 is electrically connected to the pair of current-carrying wirings 23. One brush 13 of the pair of brushes 13 is connected to the stator 17 (yoke 17 a) via a ground connection wiring 21.

Therefore, even when a spark is generated between the commutator 11 and the brush 13, the electrical noise due to the spark is absorbed by the yoke 17a via the ground connection wiring 21 and is not transmitted to the current-carrying wiring 23. In other words, even when sparks are generated between the commutator 11 and the brushes 13, the circular saw 1 can reduce the propagation of electrical noise to the current-carrying wiring 23 and reduce the amount of noise radiation from the current-carrying wiring 23 to the outside.

The pair of brushes 13 is directly connected to the pair of current-carrying wirings 23. Specifically, the brush holding portion 13b of the brush 13 is directly connected to the current-carrying wiring 23. As a method of connecting the brush 13 and the current-carrying wiring 23, a method such as soldering or welding can be used. In the present embodiment, as shown in fig. 3, the end of the current-carrying wiring 23 is welded to the connection portion 22 on the outer surface of the brush holding portion 13b.

As shown in fig. 3 and 5, the ground connection wiring 21 is connected to the brushes 13 at a position different from a connection portion 22 between the pair of current-carrying wirings 23 and the pair of brushes 13. In this way, by making the connection portion with the ground connection wiring 21 on the brush 13 and the connection portion with the current-carrying wiring 23 on the brush 13 different in position, the degree of freedom in determining the route for laying the ground connection wiring 21 is improved.

[1-4. Measurement results ]

Next, measurement for confirming the noise reduction effect in the circular saw 1 of the present embodiment will be described.

In this measurement, as a comparative example, an electric working machine having a configuration in which the ground is connected to the current-carrying wiring 23 from a midway position thereof was used. As shown in fig. 6, the electric working machine of the comparative example is configured such that a middle position 23b of the current-carrying wiring 23 is connected to the stator 17 (yoke 17 a) via a ground connection wiring 23c for comparison.

The disk saw 1 and the comparative examples were each measured for noise radiated to the outside during driving of the motor. The measurement results (noise waveforms) of the noise intensity measured for each frequency are shown in fig. 7 for the circular saw 1, and fig. 8 for the comparative example.

From the measurement results, it was found that the peak value of the noise in the circular saw 1 (14.9 [ dB [ mu ] V/m ]) was small as compared with the peak value of the noise in the comparative example (21.0 [ dB [ mu ] V/m ]). In other words, the circular saw 1 can reduce the amount of noise radiation to the outside as compared with the comparative example, and can exhibit the noise reduction effect.

In the comparative example, in the current-carrying wiring 23, the noise is propagated from the specific portion 23a to the outside due to the spark between the commutator 11 and the brush 13 at the specific portion 23a (specifically, the portion from the end connected to the brush 13 to the halfway position 23 b). In contrast, since the circular saw 1 does not transmit noise to the current-carrying wiring 23, the amount of noise radiation to the outside can be reduced.

[1-5. Effect ]

According to the above-described embodiment, the following effects can be obtained.

In the circular saw 1 of the present embodiment, one of the pair of brushes 13 is connected to the yoke 17a via the ground connection wiring 21, so that even when a spark is generated between the commutator 11 and the brush 13 in the motor 2, the electrical noise due to the spark is absorbed by the yoke 17a via the ground connection wiring 21. In other words, even when a spark is generated between the commutator 11 and the brush 13, the circular saw 1 can reduce the propagation of electrical noise to the current-carrying wiring 23 and suppress the radiation of noise from the current-carrying wiring 23 to the outside.

Thus, according to the circular saw 1, it is possible to reduce adverse effects on other electrical devices present around the circular saw 1 when electrical noise of the motor 2 is generated while suppressing an increase in the number of components such as capacitors.

In the circular saw 1, the yoke 17a of the stator 17 is a member having a larger volume than the brush 13. Therefore, by electrically connecting the brush 13 and the yoke 17a, the yoke 17a can sufficiently absorb the electrical noise due to the spark between the commutator 11 and the brush 13.

Next, even when the distance between the brush 13 and the commutator 11 changes, the brush body portion 13a (more specifically, the contact portion 13a 1) slides inside the brush holding portion 13b, and therefore the connection state with the commutator 11 can be maintained. Further, since the ground connection wiring 21 is connected to the brush holding portion 13b, the ground connection wiring 21 can be electrically connected to the brush 13, and the brush 13 can be electrically connected to the yoke 17 a.

Thus, according to the circular saw 1, even when the distance between the brush 13 and the commutator 11 changes, the brush 13 and the yoke 17a can be electrically connected to each other, and therefore, adverse effects on other electrical devices due to electrical noise of the motor 2 can be reduced.

Next, the ground connection wiring 21 is connected to the brushes 13 at a position different from a connection position of the pair of current-carrying wirings 23 and the pair of brushes 13. In this way, by making the connection portion of the brush 13 with the ground connection wiring 21 and the connection portion of the brush 13 with the current-carrying wiring 23 different in position, the degree of freedom in determining the path for laying the ground connection wiring 21 is improved. This can suppress interference between the ground connection wiring 21 and the current-carrying wiring 23, and reliably connect the ground connection wiring 21 to the brush 13.

Thus, according to the circular saw 1, the ground connection wiring 21 can be reliably connected to the brush 13, and the electric connection between the brush 13 and the yoke 17a can be established, so that the adverse effect on other electric devices due to the electric noise of the motor 2 can be reduced.

[1-6. Correspondence of sentences ]

Here, the correspondence relationship between words in the present embodiment will be described.

The circular saw 1 corresponds to an example of an electric working machine, the motor 2 corresponds to an example of a motor, and the saw blade 16, the blade housing 20, the gear mechanism 12, the output shaft 14, the bearing 24, the support member 24a, the bolt 18, the clamping member 19A, the clamping member 19B, and the cover 26 correspond to an example of a working portion.

The current-carrying wiring 23 corresponds to an example of a current-carrying wiring, the mechanical commutator 11 corresponds to an example of a commutator, the pair of brushes 13 corresponds to an example of a pair of brush portions, the brush body portion 13a corresponds to an example of a brush body portion, the brush holding portion 13b corresponds to an example of a brush holding portion, and the stator 17 corresponds to an example of a stator. The ground connection wiring 21 corresponds to an example of a ground connection wiring, and the yoke 17a corresponds to an example of a ground metal portion.

[2. Other embodiments ]

The embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above embodiments, and can be implemented in various forms without departing from the scope of the present disclosure.

(1) In the above embodiment, the description has been given of the configuration in which the connection portion between the grounding connection wiring 21 and the brush 13 and the connection portion between the current-carrying wiring 23 and the brush 13 are different, but the present disclosure is not limited to such a configuration. For example, as shown in fig. 9, the connection portion between the ground connection wiring and the brush portion and the connection portion between the current-carrying wiring and the brush portion may be at the same position. In other words, the ground connection wiring and one of the pair of current-carrying wirings may be connected to the brush portion at the same position. In this way, by adopting the configuration in which the grounding connection wiring and the conducting wiring are connected to the brush portion at the same position, the work of connecting the grounding connection wiring and the brush portion and the work of connecting the conducting wiring and the brush portion can be performed in one operation. For example, when the connection work is performed by soldering, the end portion of the current-carrying wiring and the end portion of the ground connection wiring can be collectively soldered to the brush portion. Thus, according to the electric working machine having such a configuration, the connection operation at the time of manufacturing can be simplified, and therefore, the manufacturing cost can be reduced.

As an example, as shown in fig. 10, both the end of the ground connection wiring 21 and the end of the current-carrying wiring 23 may be welded to the connection portion 22 of the brush holding portion 13b of the brush 13.

(2) In the above embodiment, the configuration in which the brush body portion 13a of the brush 13 is connected to the ground connection wiring 21 has been described, but the present disclosure is not limited to such a configuration. For example, as shown in fig. 10, the brush 13 may have a structure in which the brush holding portion 13b is connected to the ground connection wiring 21.

The configuration in which the brush body portion 13a is connected to the ground connection wiring 21 is not limited to the configuration in which the contact portion 13a1 of the brush body portion 13a is connected to the ground connection wiring 21 as in the above-described embodiment, and may be a configuration in which the connection portion 13a2 of the brush body portion 13a is connected to the ground connection wiring 21 as shown in fig. 11.

In the configuration in which both the ground connection wiring 21 and the current-carrying wiring 23 are connected to the brush body portion 13a, as shown in fig. 11, the first connection portion 22a of the brush body portion 13a (more specifically, the connection portion 13a 2) to the ground connection wiring 21 and the second connection portion 22b of the brush body portion 13a to the current-carrying wiring 23 may be at different positions. Although not shown, in the configuration in which both the ground connection wiring 21 and the current-carrying wiring 23 are connected to the brush holding portion 13b, the connection portion of the brush holding portion 13b to the ground connection wiring 21 and the connection portion of the brush holding portion 13b to the current-carrying wiring 23 may be at different positions.

(3) In the above embodiment, the configuration in which the brush 13 is electrically connected to the stator 17 (yoke 17 a) via the ground connection wiring 21 has been described, but the present disclosure is not limited to such a configuration. For example, as shown in fig. 12, the brush 13 may be electrically connected to the blade case 20 via a ground connection wiring 21. In this case, the blade case 20 is made of a conductive metal material (iron or the like), and is provided as a part of the working portion of the electric working machine. Since the blade case 20 is a member having a larger volume than the brush 13, it can sufficiently absorb the electrical noise caused by the spark. In this case, the blade case 20 corresponds to an example of the ground metal part.

(4) The electric working machine is not limited to the above-described circular saw, and may be, for example, an electric hammer drill, an electric screwdriver, an electric wrench, an electric reciprocating saw, an electric wire saw, an electric cutter, an electric chain saw, an electric planer, an electric riveter, an electric nailing machine, an electric trimmer, an electric lawn trimmer, an electric brush cutter, an electric cleaner, an electric blower, a grinder, or the like.

(5) The functions of one component in the above embodiments may be distributed into a plurality of components, or the functions of a plurality of components may be integrated into one component. At least a part of the structure of the above embodiment may be replaced with a known structure having the same function. In addition, a part of the configuration of the above embodiment may be omitted. At least a part of the structure of the above embodiment may be added to or replaced with the structure of another embodiment. All the aspects included in the technical idea defined only by the terms described in the claims are embodiments of the present disclosure.

Description of the reference numerals

1, 8230, circular saw 2, 8230, motor 4, 8230, rotary shaft 9, 8230, rotor 10, 8230, main body shell 11, mechanical commutator 13, 8230, brush 13, 8230, main body part 13, 8230, contact part 13, 8230, curved

surface

13, 2, 8230, connecting part 13, 3, 8230, elastic part 13, 8230, brush holding part 16, 8230, saw blade 17, 8230, stator 17, 8230, yoke iron, 17, 8230, permanent magnet 20, 8230, saw blade shell 21, 8230, earthing connection wire 23, 8230, electrifying wire 26, 8230cover 33, 8230, fixing screw 35, 823052, and ring-shaped washer.

Claims

1. An electric working machine is provided with:

a motor having a rotor that rotates by supply of driving electric power from outside;

an operating unit to which the rotational force of the rotor is transmitted to operate; and

a pair of power supply lines for supplying the driving electric power to the motor,

the motor includes:

a commutator that rotates together with the rotor;

a pair of brush portions electrically connected to the pair of current-carrying wirings, the pair of brush portions being electrically connected to and disconnected from the commutator repeatedly with rotation of the rotor; and

a stator including a yoke disposed outside the rotor,

the electric working machine includes:

a ground connection wiring electrically connected to one of the pair of brush portions; and

a grounding metal part electrically connected to the grounding connection wiring and having a larger volume than the brush part,

the brush part comprises a brush main body part and a brush holding part,

the brush body portion is electrically connected to the commutator and is formed using at least a conductive carbon material,

the brush holding portion is a member that holds the brush body portion in a state in which the brush body portion is slidable inside the brush holding portion, and is formed using at least a conductive metal material,

the ground connection wiring is connected to at least one of the brush body portion and the brush holding portion.

2. The electric working machine according to claim 1,

the grounding metal part is the yoke of the stator.

3. The electric working machine according to claim 1,

the working part comprises a metal, and the working part comprises a metal,

the grounding metal part is the working part.

4. The electric working machine according to claim 1,

the ground connection wiring is connected to the brush body portion.

5. The electric working machine according to claim 1,

the ground connection wiring is connected to the brush holding portion.

6. The electric working machine according to any one of claims 1 to 5,

the pair of current-carrying wirings are directly connected to the pair of brush portions,

the ground connection wiring and one of the pair of current-carrying wirings are connected to the brush portion at the same position.

7. The electric working machine according to any one of claims 1 to 5,

the ground connection wiring is connected to the brush portion at a position different from a connection portion between the pair of current-carrying wirings and the pair of brush portions.