Preload detectable screw device
AssigneeThk Co., Ltd.
InventorsYuji Kubota, Hirofumi Suzuki, Takamitsu Tomiyama, Yuta Tsujisawa
Life of this patent
Estimating the term…
Abstract
A screw device is provided which applies preload with a single nut and can easily detect preload. The screw device of includes: a screw shaft having an outer helical groove; a nut fitted on the screw shaft, the nut having an inner helical groove, and a return path to which a passage formed between the outer groove and the inner groove is connected; a plurality of rolling elements placed between the passage and the return path; and a strain sensor attached to an outer surface of the nut. At least one hole is provided between an attachment surface, to which the strain sensor is attached, of the nut and/or a vicinity thereof and an inner surface of the nut.
Claims12
A preload detectable screw device comprising:
- a screw shaft including an outer helical groove;
- a single nut fitted on the screw shaft, the single nut including an inner helical groove, and a return path to which a passage formed between the outer groove and the inner groove is connected;
- a plurality of rolling elements placed in the passage and the return path;
- and
- a strain sensor attached to an outer surface of the single nut,
- wherein at least one hole is provided between an attachment surface, to which the strain sensor is attached, of the single nut and an inner surface, to which the inner groove is formed, of the single nut.
A preload detectable screw device comprising:
- a screw shaft including an outer helical groove;
- a nut fitted on the screw shaft, the nut including an inner helical groove, and a return path to which a passage formed between the outer groove and the inner groove is connected;
- a plurality of rolling elements placed in the passage and the return path;
- and
- a strain sensor attached to an outer surface of the nut,
- wherein at least one hole is provided between an attachment surface, to which the strain sensor is attached, of the nut and an inner surface of the nut,
- wherein the screw device uses the plurality of rolling elements that are larger than the passage to provide oversized ball preloading, and
- the strain sensor detects strain on the nut at least in a circumferential direction thereof.
Dependencies are inferred from the claim text.