JP2012114972A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the fact that when a carbon brush is worn and energization force of a spring becomes weak, upon application of vibration occurred during use of a power tool onto a contact surface between the carbon brush and a commutator, a contact state therebetween is deteriorated, and an arc occurs on the contact surface between the carbon brush and the commutator, thereby causing melting and wear of a contact part, resulting in a short life of the carbon brush and the commutator.SOLUTION: A permanent magnet 16 is disposed inside a carbon brush 8, and an iron sleeve 19 is disposed inside a commutator 18. Thereby, the carbon brush 8 is sucked toward a commutator 13 by suction force of the permanent magnet 16 and the iron sleep 19, thus allowing the carbon brush 8 and the commutator 18 to be maintained in a stable contact state.

Description

  The present invention relates to a power tool.

  Some conventional power tools use a commutator motor as a drive source for rotating a bit serving as a tip tool. As shown in FIG. 2 of Patent Document 1, the commutator motor rotates when electric power is supplied to the commutator via the carbon brush. The carbon brush is put in a brush holder provided in the housing of the electric tool and covered with a brush cap. A spring that biases the carbon brush toward the commutator is provided between the brush cap and the carbon brush.

JP 2008-044023 A

  In the conventional carbon brush holding structure of an electric power tool, the carbon brush is worn out as the motor is driven, so that the urging force to the commutator side by the spring is reduced. In this state, when vibration generated when using the electric tool is applied to the contact surface between the carbon brush and the commutator, the contact state is deteriorated, and an arc is generated on the contact surface between the carbon brush and the commutator, The contact part melts and wears, and the life of the carbon brush and the commutator is shortened.

  Therefore, an object of the present invention is to provide an electric tool that can stabilize the contact between the carbon brush and the commutator even when the carbon brush is worn.

  The above object includes a housing, a motor including a rotor fixed to the housing and a rotor having a commutator, a carbon brush that contacts the commutator, and a brush holder that accommodates the carbon brush. In the electric tool, the rotor may have an iron member at a position facing the carbon brush, and the carbon brush may have a permanent magnet at a position facing the iron member.

  According to such a configuration, since the permanent magnet is attracted to the iron member, the carbon brush and the commutator can be maintained in a stable contact state even if the carbon brush is worn, and the life of the carbon brush and the commutator is reduced. Can be suppressed.

  Moreover, it is preferable that the said iron member is provided over the perimeter of the said rotor. According to such a configuration, since the permanent magnet always faces the iron member even when the rotor rotates, the carbon brush and the commutator can be maintained in a stable contact state.

  Further, the object is to provide a housing, a motor composed of a rotor having a stator and a commutator fixed to the housing, a carbon brush that contacts the commutator, and a brush holder that accommodates the carbon brush. In the electric tool provided, the rotor has a first permanent magnet at a position facing the carbon brush, and the carbon brush has a second permanent magnet at a position facing the iron member, This can be achieved by arranging the first permanent magnet and the second permanent magnet so as to attract each other.

  According to such a configuration, since the permanent magnets attract each other, the carbon brush and the commutator can be maintained in a stable contact state even when the carbon brush is worn, and the lifetime reduction of the carbon brush and the commutator is suppressed. be able to.

  The first permanent magnet is preferably provided over the entire circumference of the rotor. According to such a configuration, since the second permanent magnet always faces the first permanent magnet even when the rotor rotates, the carbon brush and the commutator can be maintained in a stable contact state. .

  Moreover, it is preferable that a spring for urging the carbon brush toward the commutator is provided in the brush holder. According to such a configuration, even when the carbon brush is not worn, the carbon brush is biased toward the commutator by the spring, so that the carbon brush and the commutator can be maintained in a stable contact state. it can.

  According to the present invention, even when the carbon brush is worn, the carbon brush and the commutator can be maintained in a stable contact state. Furthermore, when the carbon brush is not worn, the carbon brush and the commutator can be maintained in a stable contact state.

It is principal part sectional drawing of the electric tool used as this invention. It is an enlarged view of the motor part of the electric tool of FIG. It is AA sectional drawing of FIG.

  The power tool of the present invention will be described with reference to FIG. An electric driver 1 that is an electric tool includes a housing 2 that is an outer frame, a handle portion 3 connected to the housing 2, a chuck portion 4 that holds a tip tool such as a drill bit, and a trigger switch 5. Inside the housing 2 are a carbon brush 8 that is supplied with power from a power source (not shown) such as an AC power source, a motor unit 6 that is in contact with the carbon brush 8 and is supplied with power from the power source, and the rotation of the motor unit 6 is advanced And a gear portion 7 for transmitting to the tool.

  When using the electric driver 1, the operator attaches a drill bit as a tip tool to the chuck portion 4, and operates (turns on) the trigger switch 5, so that power from the power source passes through the carbon brush 8. It is transmitted to the motor unit 6. As the motor unit 6 rotates, the gear unit 7 connected to the rotation shaft of the motor unit 6 rotates, and the rotation of the motor unit 6 is decelerated, and the rotation is transmitted to the tip tool so that a desired work can be performed. .

  The detailed structure of the motor unit 6 will be described with reference to FIGS. The motor unit 6 is mainly composed of a rotor 10 and a stator 6a. The rotor 10 is a rectifier that supplies power to the coil 11 by contacting the rotating shaft 9, a coil 11 wound in a slot (not shown) of the rotor 10, and a carbon brush 8 provided on one end side of the rotating shaft 9. And a child 18. The rotor 10 is press-fitted into the rotating shaft 9. The stator 6a is fixed in the housing 2 facing the rotor 10 (FIG. 1). An insulating member 12 for insulation is provided between the rotating shaft 9 and the coil 11. The carbon brush 8 is provided symmetrically with respect to the axis 9a of the rotating shaft 9.

  The carbon brush 8 is accommodated in a brush holder 14 fixed inside the housing 2 and supported in the housing 2. The brush holder 14 internally has a stop piece 17 for supplying power from the power source to the carbon brush 8, one end is fixed to the stop piece 17 and the other end is fixed to the carbon brush 8, and the carbon brush 8 is rectified. A spring 15 is provided to bias the child 18 side. The power supply unit 17 and the carbon brush 8 are connected by a connection unit (pigtail) 17 a and supply power from the power source to the commutator 18. Further, a permanent magnet 16 is provided inside the carbon brush 8. In addition, an iron sleeve 19 is press-fitted into the rotating shaft 9, and a commutator 18 is fixed to the outer peripheral portion of the rotating shaft 9 via a resin 13. The iron sleeve 19 is provided over the entire circumference of the portion of the rotating shaft 9 where the commutator 18 is provided.

  Here, in the commutator motor used in the conventional electric tool, the carbon brush 8 is only urged toward the commutator 18 by the spring 15, so when the carbon brush 8 is worn, the spring 15 The urging force is weakened, and the carbon brush 8 and the commutator 18 may cause poor contact. Therefore, in the present invention, an iron sleeve 19 is provided on the rotating shaft 9 and a permanent magnet 16 is incorporated in the carbon brush 8.

  By adopting such a configuration, the carbon brush 8 can be urged toward the commutator 18 by the urging force of the spring 15 in the state where the carbon brush 8 is not worn. In addition, since the permanent magnet 16 is attracted to the iron sleeve 19, a stable contact state can be maintained by the strong biasing force of the spring 15 and the permanent magnet. On the other hand, when the carbon brush 8 is worn, the distance between the upper part of the brush holder 14 (the part to which one end of the spring 15 is attached) and the carbon brush 8 becomes longer and the urging force of the spring 15 becomes weaker. Since the distance between the steel sleeve 19 and the iron sleeve 19 is shortened, the suction force is increased. Therefore, even if the urging force of the spring 15 becomes weak, a stable contact state can be maintained by the permanent magnet 16.

  That is, the carbon brush 8 and the commutator 18 are maintained in a stable contact state by the biasing force of the spring 8 when the carbon brush 8 is not worn and by the attractive force of the permanent magnet 16 when the carbon brush 8 is worn. It is possible to prevent the lifetime of the carbon brush 8 and the commutator 18 from being shortened.

  In the present embodiment, the iron sleeve 19 provided on the rotating shaft 9 and the permanent magnet 16 are provided so as to attract each other. With such a configuration, as the carbon brush 8 is worn, the distance between the permanent magnet 16 and the iron sleeve 19 is shortened, so that the attractive force thereof increases. Therefore, it is possible to always maintain a stable contact state regardless of the worn state of the carbon brush 8. A permanent magnet may be provided instead of the iron sleeve 19, and the two permanent magnets may be provided in a direction that attracts each other. In other words, any configuration may be used as long as the carbon brush 8 can be biased toward the commutator 18 side. However, when the carbon brush 8 is worn as in the present embodiment, the carbon brush 8 is connected to the commutator 13 side. It is most preferable to provide a permanent magnet so that it can be urged strongly.

  6 is a motor unit, 8 is a carbon brush, 9 is a rotating shaft, 10 is a rotor, 11 is a coil, 12 is an insulating member, 14 is a brush holder, 15 is a spring, 16 is a permanent magnet, 18 is a commutator, 19 is It is an iron sleeve.

Claims (5)

A housing;
A motor comprising a rotor having a stator and a commutator fixed to the housing;
A carbon brush in contact with the commutator;
A brush holder for housing the carbon brush;
In the electric tool with
The rotor has an iron member at a position facing the carbon brush, and the carbon brush has a permanent magnet at a position facing the iron member.   The electric tool according to claim 1, wherein the iron member is provided over the entire circumference of the rotor. A housing;
A motor comprising a rotor having a stator and a commutator fixed to the housing;
A carbon brush in contact with the commutator;
A brush holder for housing the carbon brush;
In the electric tool with
The rotor has a first permanent magnet at a position facing the carbon brush, and the carbon brush has a second permanent magnet at a position facing the iron member, the first permanent magnet and the carbon brush The power tool, wherein the second permanent magnets are arranged so as to attract each other.   The electric tool according to claim 3, wherein the first permanent magnet is provided over the entire circumference of the rotor.   The electric tool according to any one of claims 1 to 4, wherein a spring for urging the carbon brush toward the commutator is provided in the brush holder.