Patent attributes
The present invention discloses a rotation device for a vehicle seat. The device includes a fixed disc, a lower ball assembly, a movable disc, an upper ball assembly, and a platen successively arranged from bottom to top. A first lower circular track is formed on the fixed disc. A first upper circular track and a second lower circular track are formed on the movable disc. A second upper circular track is formed on the platen. A diameter of a first arcuate envelope line of the first lower circular track that is in contact with a lower ball and a diameter of a second arcuate envelope line of the first upper circular track that is in contact with the lower ball are both equal to a diameter of the lower ball, and a height of the first arcuate envelope line and a height of the second arcuate envelope line are 0.8 times the diameter of the lower ball. A diameter of a third arcuate envelope line of the second lower circular track that is in contact with an upper ball and a diameter of a fourth arcuate envelope line of the second upper circular track that is in contact with the upper ball are both equal to a diameter of the upper ball, and a height of the third arcuate envelope line and a height of the fourth arcuate envelope line are both 0.8 times the diameter of the upper ball. By means of the present invention, a smooth rotary operating force can be achieved, and a service life of the rotation device can be properly prolonged.
