Leaf blower
A blower assembly for a leaf blower has a case, a motor, an impeller driven by the motor, and an axial fan driven by the motor. The axial fan and the impeller are connected to opposite ends of the motor. The case has an air inlet, an air outlet and an air channel communicating the air inlet with the air outlet. The impeller is disposed inside the air channel to move air through the air channel from the air inlet to the air outlet. The axial fan is arranged to generate an axial flow of air towards the motor to cool the motor.
1. A blower comprising: a case, a motor and an impeller driven by the motor,
wherein the case comprises an air inlet, an air outlet, and an air channel communicating the air inlet with the air outlet, the impeller being disposed inside the air channel,
wherein the motor comprises a stator and a rotor rotatably mounted to the stator, the stator comprising a stator core which comprises a yoke, P primary poles with stator windings wound thereon and P auxiliary poles, the primary poles and auxiliary poles being alternately arranged on the radially inner side of the yoke in a circumferential direction thereof,
when the stator windings are electrified, P primary magnetic poles and P auxiliary magnetic poles are formed at the primary poles and auxiliary poles, respectively, the polarity of the primary magnetic poles being opposite to the polarity of the auxiliary magnetic poles, P being an integer greater than one;
wherein the rotor comprises a shaft, a rotor core, a rotor winding comprising m winding units where m is an even integer greater than P, and a commutator fixed onto the shaft;
wherein the commutator comprises m segments, every two adjacent segments of the m segments being electrically connected together by a winding unit; and
at least one of the m winding units comprises P coils connected in series, and opposite ends of each coil are directly connected to corresponding two of the m segments.
2. The blower of claim 1 , wherein for the winding unit connected to first segment Z X and an adjacent second segment Z X+1 and comprising more than one coil, every two adjacent coils of the winding unit is directly connected to a shared segment Z Y which is under the same polarity as the first segment Z X or the second segment Z X+1 .
3. The blower of claim 2 , wherein additional windings are wound on the auxiliary poles, the additional windings wound about each auxiliary pole having less turns than the stator windings wound about each primary pole.
4. The blower of claim 2 , wherein the outer diameter D of the rotor core and the minimum outer diameter Y of the stator core meets the following equation: D/Y>6:10.
5. The blower of claim 2 , wherein the yoke comprises P primary yoke portions from which the primary poles extend inwardly and P auxiliary yoke portions from which the auxiliary poles extend inwardly.
6. The blower of claim 5 , wherein holes are formed in the auxiliary yoke portions.
7. The blower of claim 5 , wherein the radial thickness of each primary yoke portion is larger than the radial thickness of each auxiliary yoke portion.
8. The blower of claim 1 , wherein m is a multiple of P, and the rotor core comprises n teeth, wherein n is a multiple of P and is greater than P.
9. The blower of claim 2 , wherein there are no stator windings wound about the auxiliary poles.
10. The blower of claim 2 , wherein each of the primary poles and auxiliary poles comprises a neck portion inwardly extending from the yoke and an arc shape pole shoe which confronts the rotor; the radial length of the neck portion of each primary pole is larger than the radial length of the neck portion of each auxiliary pole.
11. The blower of claim 2 , wherein the blower comprises an axial fan driven by the motor to generate an axial flow of air towards the motor, the axial fan and the impeller being respectively disposed at opposite ends of the motor.