Patent ID: 7086296
Filing Date: 2006-08-08
Classification: B62D,G01L

Abstract:
1. A torque sensor comprising: a first shaft made from magnetic material; a second shaft connected to said first shaft so that they can rotate elastically with respect to each other; a magnetic leak prevention member made from nonmagnetic material and covering the outer periphery of said first shaft; a first detection tube made from magnetic material and covering the outer periphery of said magnetic leak prevention member; a second detection tube made from magnetic material, integrated with said second shaft so that they can rotate together, and disposed so that one end thereof faces one end of said first detection tube via a gap; and a coil constituting a magnetic circuit by generating magnetic flux passing through the one end of said first detection tube and the one end of said second detection tube; wherein a plurality of teeth that are arranged along the circumferential direction are provided at the one end of said first detection tube and at the one end of the second detection tube so that magnetic resistance to magnetic flux in said magnetic circuit changes according to the amount of relative rotation of the two shafts; said magnetic leak prevention member is molded from synthetic resin material poured into a mold; said first shaft and said first detection tube are integrated with said molded magnetic leak prevention member so that they can rotate together, by being inserted in said mold before the synthetic resin material is poured thereinto; each space between said adjacent teeth arranged along the circumferential direction at the one axial end of said first detection tube serves as a resin holding space; said magnetic leak prevention member has a portion solidifying in said resin holding spaces; and circumferential width of said resin holding space decreases gradually toward the other axial end of the first detection tube so that the synthetic resin material solidified in said resin holding spaces is pressed against said teeth due to shrinkage thereof.