Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Casing having multiple parts releasably clamped
Reexamination Certificate
2001-04-06
2003-10-21
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Casing having multiple parts releasably clamped
C285S903000
Reexamination Certificate
active
06634857
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a manually guided suction device or blower having a housing in which is formed a spiral blower path in which is disposed an impeller that is rotatably driven by a drive motor. The housing has an air inlet for conveying air to the spiral blower path, and an air outlet for withdrawal of air therefrom. A connector is secured to the housing and is embodied for the detachable connection of an air-conveying connection conduit, whereby when the connection conduit is mounted it overlaps with the connector over a prescribed axial length.
DE 198 33 837 A1 discloses a portable suction device or blower having a housing in which is formed a spiral blower path in which is accommodated an impeller that is rotatably driven by a drive motor. When the motor is running, air is supplied to the spiral blower path via an air inlet, and air is withdrawn from the spiral blower path via the air outlet. An air-conveying connection conduit can be mounted in a connector that is secured to the housing at the air outlet. When the connection conduit is mounted, it and the fixed connector overlap one another over a prescribed axial length. In this overlap region a mechanical connection, in particular a bayonet joint, is provided that is formed from guide ways or tracks that are provided in the outer surface of the connector, as well as from radial cams or projections that are provided on the connection conduit. A cam is positively secured in the peripheral portion of a guide way by means of a snap connection. The connection conduit is axially fixed in position, and is secured against rotation, by the bayonet joint.
In order to be able to easily assemble and disassemble the bayonet joint, an appropriate assembly gap, in other words a radial play, must be provided in the overlap region. In this connection, the non-rotatable connection is established exclusively via the detent or latch that secures the connection conduit in the end position. The bayonet joint has proven to be satisfactory as a connection that can absorb high forces; however, as the operating time increases, a high degree of wear of the snap connection that secures the bayonet closure in the end position was discovered. The cause for this is that not only during suction operation but also during blowing operation the free end of the suction or blower conduit comes into contact with the ground, as a result of which, due to the long lever, considerable forces become effective in the connection region. Over time, this leads to an undesirable loosening of the bayonet joint, and can adversely affect the operation of the suction device or blower.
It is therefore an object of the present invention to improve a suction device or blower of the aforementioned general type in such a way that a mechanically secure connection of the connection conduit is ensured over a long period of operation.
REFERENCES:
patent: 4922583 (1990-05-01), Wentworth
patent: 5971438 (1999-10-01), Johnson
patent: 198 33 837 (2000-02-01), None
Kramer Jochen
Lange Karl-Heinz
Andreas Stihl AG & Co.
Becker R W
Look Edward K.
McCoy Kimya N
R W Becker & Associates
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