An angle grinder includes a housing, an output shaft, and a motor. The motor includes a stator assembly, a rotor assembly including a motor shaft configured to rotate about a first axis, a commutator, and a carbon brush. The commutator includes a bushing, configured to connect the commutator to the motor shaft, a plurality of commutator segments, sequentially distributed in a circumferential direction around the first axis and arranged around the bushing, and an insulating member, configured to bond the bushing and the plurality of commutator segments so as to constitute a whole.

A DC motor is provided that can suppress a commutator from wearing. A DC motor including a commutator formed of copper or a copper alloy of 99% or more copper, and a brush pressed against and in contact with the commutator, wherein the brush is composed of a sintered compact including graphite and copper powder, hard compound particles higher in hardness than any of the copper or the copper alloy and the graphite or the copper powder are contained in at least one of the commutator and the brush and are scattered on or near a contact surface of the commutator with the brush at least during use.

A DC motor is provided that can suppress a commutator from wearing. A DC motor including a commutator formed of copper or a copper alloy of 99% or more copper, and a brush pressed against and in contact with the commutator, wherein the brush is composed of a sintered compact including graphite and copper powder, hard compound particles higher in hardness than any of the copper or the copper alloy and the graphite or the copper powder are contained in at least one of the commutator and the brush and are scattered on or near a contact surface of the commutator with the brush at least during use.

A direct-current motor commutator structure includes: a commutator base, comprising a front pressing ring, a pressing plate and a sleeve that are sequentially abutted, a sealing ring being provided between the front pressing ring and the pressing plate, and between the pressing plate and the sleeve constituting a bearing area; a commutator, mounted in the bearing area and having opposite first and second portions; a sealing element being potted or provided between the second portion and the sleeve; an equalizing cable, mounted on an outer side of a first potting area formed by the first portion, the pressing plate and the front pressing ring, abutting against the first portion and the front pressing ring, and covering the first potting area; and an armature coil, clinging to the equalizing cable and located on an outer side of a second potting area formed by the equalizing cable and the front pressing ring.

A direct-current motor commutator structure includes: a commutator base, comprising a front pressing ring, a pressing plate and a sleeve that are sequentially abutted, a sealing ring being provided between the front pressing ring and the pressing plate, and between the pressing plate and the sleeve constituting a bearing area; a commutator, mounted in the bearing area and having opposite first and second portions; a sealing element being potted or provided between the second portion and the sleeve; an equalizing cable, mounted on an outer side of a first potting area formed by the first portion, the pressing plate and the front pressing ring, abutting against the first portion and the front pressing ring, and covering the first potting area; and an armature coil, clinging to the equalizing cable and located on an outer side of a second potting area formed by the equalizing cable and the front pressing ring.

A brushed motor includes a rotation shaft, a commutator including a plurality of segments separated by a plurality of undercuts arranged at unequal intervals, an armature, a plurality of permanent magnets, a voltage equalizing line, a positive electrode brush, and a negative electrode brush. When Pz is the number of the permanent magnets and N is the number of the segments, a relationship of N=Pz(K−0.5) is satisfied. Pz is an even number that is greater than or equal to four. K is a constant and is a natural number that is greater than or equal to two. The plurality of undercuts includes at least one set of undercuts arranged at an undercut interval that differs from a reference angle θz. The reference angle θz is specified by a relational expression of θz=(360 degrees/Pz)±(360 degrees/2N).

A brushed motor includes a rotation shaft, a commutator including a plurality of segments separated by a plurality of undercuts arranged at unequal intervals, an armature, a plurality of permanent magnets, a voltage equalizing line, a positive electrode brush, and a negative electrode brush. When Pz is the number of the permanent magnets and N is the number of the segments, a relationship of N=Pz(K−0.5) is satisfied. Pz is an even number that is greater than or equal to four. K is a constant and is a natural number that is greater than or equal to two. The plurality of undercuts includes at least one set of undercuts arranged at an undercut interval that differs from a reference angle θz. The reference angle θz is specified by a relational expression of θz=(360 degrees/Pz)±(360 degrees/2N).

The present invention provides a motor comprising: a rotary shaft; a rotor including a hole in which the rotary shaft is disposed; a stator disposed on the outer side of the rotor; and a housing for accommodating the rotor and the stator, and further comprising a rectifier having a hole in which the rotary shaft is disposed, wherein the housing includes a cover plate, the cover plate includes a brush coming into contact with the rectifier, and the front surface of the brush includes a curved part coming into contact with the rectifier, and a cutting part formed to be bent from the curved part such that the cutting part does not come into contact with the rectifier, thereby providing an advantageous effect of inhibiting the worn foreign material of the brush from being generated on a contact portion between the brush and the rectifier during the initial driving of the motor.

The present invention provides a motor comprising: a rotary shaft; a rotor including a hole in which the rotary shaft is disposed; a stator disposed on the outer side of the rotor; and a housing for accommodating the rotor and the stator, and further comprising a rectifier having a hole in which the rotary shaft is disposed, wherein the housing includes a cover plate, the cover plate includes a brush coming into contact with the rectifier, and the front surface of the brush includes a curved part coming into contact with the rectifier, and a cutting part formed to be bent from the curved part such that the cutting part does not come into contact with the rectifier, thereby providing an advantageous effect of inhibiting the worn foreign material of the brush from being generated on a contact portion between the brush and the rectifier during the initial driving of the motor.

A rotor is provided with: a rotor core which rotates integrally with a shaft and has a plurality of radially extending teeth; windings including coil portions wound around the teeth; a commutator that is attached to the rotor core and integrally rotates with the shaft, the commutator including metal commutator segments having contact portions with which precious metal brushes make sliding contact, and a plurality of terminals to which the windings are bonded; elements which include capacitors and respectively electrically connecting terminals to which both ends of the coil portions of the same phase are connected; and a coating layer formed of an oil applied to the contact portions. A motor includes this rotor.