Compact ball screw assembly
AssigneeNippon Thompson Co., Ltd.
InventorKunihiko Morita
Life of this patent
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Abstract
A ball screw assembly includes a screw shaft hving a peripheral surface formed with a spiral groove, an outer sleeve fitted onto the screw shaft with a predetermined gap therebetween and a plurality of balls interposed between the screw shaft and the outer sleeve. A ball holder is provided in a radial hole formed in the outer sleeve and a ball is rotatably held in position and in engagement with the spiral groove by the ball holder. A fluid line is formed in the outer sleeve and the ball holder so that a pressuerized fluid may be supplied to establish a fluidic cushion between the ball holder and the ball. Also provided is a plurality of solid lubricants which are preferably arranged alternately with the balls and normally pressed against the spiral groove to keep the groove lubricated at all times.
Claims11
A ball screw assembly comprising:
- a screw shaft having a peripheral surface formed with a spiral groove having a predetermined pitch;
- an outer sleeve fitted onto said screw shaft with a predetermined gap therebetween said outer sleeve being formed with a first plurality of radial holes;
- holding means provided in said outer sleeve for holding a plurality of balls in position and in engagement with said spiral groove said holding means including a first plurality of ball holders capable of threadably fitting into a corresponding one of said first plurality of radial holes, each of said first plurality of ball holders having an inner end which is substantially concave in shape to receive therein a corresponding ball partly;
- and
- pressurized fluid supplying means provided in said outer sleeve for supplying pressurized fluid to each of said plurality of balls such that a fluidic cushion is formed between said holding means and each of said plurality of balls at least partly.
Dependencies are inferred from the claim text.