Nsk Corporation

Takayuki Miyagawa

Mamoru Aoki

Hiroshi Ishiwada

Masato Taniguchi

Hirotoshi Aramaki

Toru Takamizawa

Tatsunobu Momono

Banda Noda

Kouichi Tanabe

Yasuyuki Muto

An endless belt () to be provided on a driven pulley () and a pulley rotation support apparatus for supporting the driven pulley (). In the pulley rotation support apparatus, there is used a three-point-contact-type or four-point-contact-type radial ball bearing (). An offset quantity &#x3b4;, which is an axial-direction distance between the center &#x3b1; of a radial load applied from the endless belt () to the driven pulley () and the center position &#x3b2; of the radial ball bearing (), is set 40% or less of the pitch circle diameter of the radial ball bearing (). The radial clearance of this radial ball bearing () is set 0.2% or less of the above pitch circle diameter.

Pulley rotation support apparatus

The frequencies generated based on the undulations existing on the inner and outer ring raceways and on the rolling surface of the balls are out of coincidence with the rotational frequency itself of the rotation member supported by the rolling bearing, and with a frequency component which is a multiple of the rotational frequency, or kinds of frequencies generated due to the undulations are out of coincidence with each other in the natural frequency domain of a rotation system which is a rotation supporting portion having the rolling bearing incorporated therein, whereby without using a special grease, the self-excited frequency of the rolling bodies hardly grows to abnormal vibration, and a rolling bearing having sufficient durability and causing no abnormal vibration and noise even if used at low temperature is realized.

Rolling bearing

A motor comprises a rotor, a stator, and a shaft wherein one of the stator and the rotor is provided with a housing, a rolling bearing is provided between the housing and the shaft and having an inner race and outer race, the inner race is fixed to the shaft through adhesion between the outer peripheral surface of the shaft and the inner peripheral surface of the inner race, the outer race is fixed to the housing through press-fitting, and the outer peripheral surface of the shaft is formed with knurled grooves, where the number (P) of the knurled grooves in the circumferential direction and the number (Z) of the rolling members in the rolling bearing are in the relations of P&nequiv;n Z and P&nequiv;nZ&plusmn;1 where n is a positive integer.

Motor with a stationary shaft with formed knurled grooves on shaft and/or housing

In the ball bearing, the ratio of the radius of curvature of an inner race raceway to the outside diameter of balls is set in the range of 0.51 to 0.54. Also, the ratio of the radius of curvature of an outer race raceway to the outside diameter of balls is set in the range of 0.54 to 0.56. Further, an interior geometric clearance c is set at 13 &mgr;m or less. Thanks to these specifications, the balls can be prevented from running up onto the edge of the outer race raceway

Growing community of inventors

Kanagawa, Japan

Takayuki Miyagawa