Brakes – Wheel – Intermittent
Patent
1986-06-26
1988-06-21
Reese, Randolph A.
Brakes
Wheel
Intermittent
188 67, 188 822, F16D 6300
Patent
active
047519860
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a rotary angle limiter to restrict the rotating angle of a rotor to more than one revolution but less than two revolutions.
BACKGROUND ART
For a mechanism which stops a rotor at a specified position exceeding one revolution with respect to a body under diagnosis such as a gantry used in an X-ray CT, a stopper becomes necessary to avoid overrunning. One type of conventional stopper consists of a stopper mounting shaft which is installed on the same axis as the rotor rotating shaft and coupled to a drive motor via reduction gears and as a result rotates less than one revolution, a stopper which is installed on this stopper mounting shaft and a stopper contact member on a rotor, wherein when the rotor rotates in the direction away from the stopper, the stopper rotates in the same direction as the rotor but at a slower speed than the rotor and the stopper contact member on the rotor after having turned one revolution clashes against the stopper, thereby stopping the rotor. Another type of conventional stopper consists of a cam which is coupled to a motor to rotate a rotor via reduction gears and a limit switch which is actuated by this cam, wherein when the rotor rotates at an angle exceeding a specified range, the power supplied to the motor is turned off by actuating the limit switch, causing the rotor to stop with the brakes on. The disadvantage of these conventional stoppers is that they require reduction gears, which increases cost and reduces reliability.
DISCLOSURE OF INVENTION
The purpose of the present invention is to provide a rotor rotating angle limiter which is less expensive and more reliable than conventional models.
A feature is that it consists of a rotor whose circumference is circular, a stator having a concentric circular arc circumference facing said rotor with a gap between them. A projection having a shorter length than the gap is installed on the circumference of the rotor facing the stator, and two projections are installed on the circumference of the stator facing the rotor, having a shorter length than the gap and arranged apart along the circumference of the stator circular arc outside of the orbit of the projection on the rotor. A rolling element is inserted between the two projections on the stator and in the gap so that it can cross the orbit of the projection on the rotor and is also movable along the gap.
BREIF DESCRIPTION OF DRAWINGS
FIG. 1 illustrates a simplified configuration of one embodiment in this invention.
FIGS. 2a-d illustrate operating diagrams of the above embodiment in this invention.
FIG. 3 illustrates a simplified configuration diagram of another embodiment in this invention.
FIG. 4 illustrates a partially modified configuration diagram of the embodiment in this invention.
FIGS. 5 and 6 illustrate simplified configuration diagrams of othe embodiment in this invention.
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a simplified configuration diagram of an embodiment of this invention. In FIG. 1, 1 is a rotor which is supported by an unillustrated support so as to be freely rotatable. If this rotor, for example, is a gantry rotor used in an X-ray CT, it is loaded by an X-ray tube and a radiation detector. 2 is the first projection installed on the circumference of rotor 1 and only one projection exists throughout the whole circumference. 3 is a stator having a circular arc facing the circumference of rotor 1 at a distance of d. 4a and 4b are the two projections installed on the circular arc of stator 3 at a specified angle of .theta. and are so shaped and sized that they do not touch projection 2 when rotor 1 rotates through one revolution. In such a dimensional example, FIG. 1 is a case where the relationship of d.sub.2 <d-d.sub.1 is established assuming that the height of projections 4a and 4b is d.sub.2, the height of projection 2 is d.sub.1 and the gap is d. 5 is a rolling element which can be a ball or cylinder whose outer diameter D is slightly smaller than gap d and is placed so as to be movable
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patent: 3094883 (1963-06-01), Junge et al.
patent: 3554337 (1971-01-01), Denkowski
patent: 4187429 (1980-02-01), Tomita et al.
Knight Anthony
Kojima Moonray
Reese Randolph A.
Yokogawa Medical Systems Limited
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