Sander

Abstract

A sander includes a housing, an electric motor, a fan assembly, an eccentric element, a base plate assembly including a base plate, a support for supporting the eccentric element. The support includes a first end surface and a second end surface opposite to each other, and the second end surface is disposed on a side of the support facing the lower surface relative to the first end surface. The sander further includes a counterweight connected to the eccentric element. The ratio of the distance from the centroid of the counterweight to the lower surface of the base plate to the distance from the first end surface of the support to the lower surface of the base plate is greater than or equal to 0.1 and less than or equal to 0.5.

What is claimed is: 
     
         1 . A sander, comprising:
 a housing;   an electric motor at least partially disposed in the housing and used for providing a power source, wherein the electric motor comprises a motor shaft that rotates about a motor axis;   a fan assembly comprising a fan connected to the electric motor;   an eccentric element driven by the electric motor, wherein the eccentric element has a central axis separated from the motor axis;   a base plate assembly comprising a base plate and a support for supporting the eccentric element, wherein the support comprises a first end surface and a second end surface opposite to each other, and the second end surface is closer to a lower surface than the first end surface; and   a counterweight connected to the eccentric element and driven by the electric motor to rotate about the central axis;   wherein a ratio of a distance from a centroid of the counterweight to the lower surface of the base plate to a distance from the first end surface of the support to the lower surface of the base plate is greater than or equal to 0.1 and less than or equal to 0.5.   
     
     
         2 . The sander of  claim 1 , wherein the counterweight comprises a body connected to the eccentric element and a centroid adjustment portion fixedly connected to or integrally formed with the body for adjusting the centroid of the counterweight. 
     
     
         3 . The sander of  claim 2 , wherein the base plate assembly further comprises a support base for mounting the support and the support base is fixedly connected to the base plate and comprises a bypass groove allowing the counterweight to rotate. 
     
     
         4 . The sander of  claim 2 , wherein the base plate comprises a groove allowing the counterweight to move and the counterweight at least partially overlaps with the base plate in an axial direction. 
     
     
         5 . The sander of  claim 4 , wherein the groove is a circular groove, a center of the groove is located on the central axis, and a ratio of an inner diameter of the groove to an outer diameter of the base plate is greater than or equal to 0.15 and less than or equal to 0.5. 
     
     
         6 . The sander of  claim 1 , wherein the counterweight comprises a weight increasing portion and a weight reducing portion, the weight reducing portion is disposed on a side of the counterweight facing the base plate, and the weight increasing portion is disposed on a side of the counterweight facing the fan. 
     
     
         7 . The sander of  claim 1 , wherein the counterweight comprises a weight increasing portion and a weight reducing portion, the weight reducing portion is disposed on a side of the counterweight facing the fan, and the weight increasing portion is disposed on a side of the counterweight facing the base plate. 
     
     
         8 . The sander of  claim 4 , wherein a product of a weight of the fan and a square of an outer diameter of the fan is greater than or equal to 40 kg·mm 2  and less than or equal to 200 kg·mm 2 . 
     
     
         9 . The sander of  claim 1 , wherein a ratio of a weight of the fan to a mass of the electric motor is greater than or equal to 3% and less than or equal to 25%. 
     
     
         10 . The sander of  claim 1 , wherein the ratio of the distance from the centroid of the counterweight to the lower surface of the base plate to the distance from the first end surface of the support to the lower surface of the base plate is greater than or equal to 0.2 and less than or equal to 0.4. 
     
     
         11 . A sander, comprising:
 a housing;   an electric motor at least partially disposed in the housing and used for providing a power source, wherein the electric motor comprises a motor shaft that rotates about a motor axis;   a fan assembly comprising a fan connected to the electric motor;   an eccentric element driven by the electric motor, wherein the eccentric element has a central axis deviating from the motor axis;   a base plate assembly comprising a base plate, a sanding member fixed to a lower surface of the base plate, and a support for supporting the eccentric element, wherein the support comprises a first end surface and a second end surface opposite to each other, and the second end surface is disposed on a side of the support facing the lower surface relative to the first end surface; and   a counterweight connected to the eccentric element and driven by the electric motor to rotate about the central axis;   wherein a ratio of a distance from a centroid of the counterweight to the lower surface of the base plate to a distance from the first end surface of the support to the lower surface of the base plate is greater than or equal to 0.1 and less than or equal to 0.5, and a product of a weight of the fan and a square of an outer diameter of the fan is greater than or equal to 40 kg·mm 2  and less than or equal to 200 kg·mm 2 .   
     
     
         12 . The sander of  claim 11 , wherein the fan is located on an upper side of the counterweight along a direction of the motor axis and a density of the fan is less than 6.5 g/cm 3 . 
     
     
         13 . The sander of  claim 11 , wherein the base plate comprises a groove allowing the counterweight to move and the counterweight at least partially overlaps with the base plate in an axial direction. 
     
     
         14 . The sander of  claim 13 , wherein the groove is a circular groove, a center of the groove is located on the central axis, and a ratio of an inner diameter of the groove to an outer diameter of the base plate is greater than or equal to 0.15 and less than or equal to 0.5. 
     
     
         15 . The sander of  claim 11 , wherein a ratio of the weight of the fan to mass of the electric motor is greater than or equal to 3% and less than or equal to 25%. 
     
     
         16 . The sander of  claim 11 , wherein the counterweight comprises a weight increasing portion and a weight reducing portion, the weight reducing portion is disposed on a side of the counterweight facing the base plate, and the weight increasing portion is disposed on a side of the counterweight facing the fan. 
     
     
         17 . The sander of  claim 11 , wherein the counterweight comprises a weight increasing portion and a weight reducing portion, the weight reducing portion is disposed on a side of the counterweight facing the fan, and the weight increasing portion is disposed on a side of the counterweight facing the base plate. 
     
     
         18 . The sander of  claim 11 , wherein the ratio of the distance from the centroid of the counterweight to the lower surface of the base plate to the distance from the first end surface of the support to the lower surface of the base plate is greater than or equal to 0.2 and less than or equal to 0.4.