Patent ID: 7695023

Claim:
A vacuum feeding joint for sealing a stream of vacuum between a fixed base and a rotating body rotatably mounted on said fixed base, the joint comprising: a fixed surface on said fixed base defining a first vacuum port; a rotated surface on said rotating body, the rotated surface being rotated with the body about an axis of rotation relative to said fixed surface and positioned opposite said fixed surface to form a gap between the surfaces, said rotated surface defining a second vacuum port; first and second annular seal member accommodating spaces circumscribing the axis of rotation and being formed in one of said fixed and rotated surfaces so as to straddle one of said first and second vacuum ports; first and second annular seal members disposed respectively in the first and second seal-member accommodating spaces; an annular communication groove formed between the annular seal accommodating spaces so as to closely coincide with a circular locus drawn on said fixed surface by an opening of said second vacuum port when said rotating body is rotated, said gap being narrower than each cross-sectional diameter of said first and second seal members, such that said first and second seal members move toward the other of said fixed and rotated surfaces at vacuum feeding from said first vacuum port to said second vacuum port and close said gap to seal members are released from the other of said fixed and rotated surfaces and open said gap to unseal said annular communication groove at termination of the vacuum feeding.