| US 7,578,228 B2 | ||
| Air balance structure | ||
| Tomohiko Kawai, Yamanashi (Japan); and Kenzo Ebihara, Yamanashi (Japan) | ||
| Assigned to FANUC Ltd, Yamanashi (Japan) | ||
| Filed on Dec. 19, 2005, as Appl. No. 11/305,190. | ||
| Claims priority of application No. 2004-371144 (JP), filed on Dec. 22, 2004. | ||
| Prior Publication US 2006/0219095 A1, Oct. 05, 2006 | ||
| Int. Cl. F13B 13/042 (2006.01) | ||
| U.S. Cl. 91—49 [92/DIG. 2] | 5 Claims |
| 1. An air balance structure for a linear drive device, comprising:
a stationary member;
a movable member having an inner space opened downward, a portion of said stationary member being inserted into the inner
space of said movable member such that said movable member is linearly movable in a vertical direction, to form an air balance
chamber containing air in the inner space of the movable member which is not occupied by the inserted portion of said stationary
member; and
an air bearing provided between an outer surface of said stationary member and an inner surface of said movable member confronting
each other, for bearing said movable member with respect to said stationary member and also sealing the air in the air balance
chamber, wherein weight of said movable member is balanced by a force due to the air in the air balance chamber pressurized
only by exhausted air from the air bearing, and the air balance chamber is provided with an exhaust port that communicates
with means for adjusting a flow of the air from the exhaust port so that the force due to the air exhausted air from the air
bearing is adjusted.
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