Rotary expansible chamber devices – With mechanical sealing – Seal element between stationary cylinder parts
Patent
1997-12-05
1999-12-07
Vrablik, John J.
Rotary expansible chamber devices
With mechanical sealing
Seal element between stationary cylinder parts
4182066, 29888023, 285917, F01C 118, F01C 1900, F16L 2100
Patent
active
059972688
DESCRIPTION:
BRIEF SUMMARY
This invention relates to pressure fluid apparatus in general. Far example, it typically relates to positive displacement hydraulic machines of the kind comprising a gear pump or motor having a body in which there are formed overlapping bores within which two gears are disposed for rotation in mash with each other. The body is adapted to accommodate the gears with minimal radial clearance at the tips of their teeth and minimal axial clearance at their end faces. The body comprises a casing with two end covers in which there are mounted bearings for supporting two parallel shafts carrying the respective gears, at least one of the covers being separate from the casing to enable the machine to be assembled and being secured to the casing as by set-screws. One end of one of the shafts projects from the body and constitutes the power input in the case of a pump and the power output in the case of a motor.
Pressure fluid apparatus may have two component parts adapted to be located together by means of a spigot or the like formed on one of them. In order to manufacture this part it is necessary to provide radiussing in the corner between the spigot or the like and a flat face on which it is formed. It then becomes necessary to provide a truncation to the corresponding corner on the other part so as to accommodate the radiussing when the two parts are assembled together. However, this arrangement has the disadvantage that a path, along which pressure fluid can leak to a space at a lower pressure is defined between the radiussing and the truncated corner.
It is an object of the present invention to overcome the aforesaid disadvantage.
Accordingly, the invention comprises pressure fluid apparatus comprising first and second parts adapted to be secured together such that a first sealing surface of the first part forms a seal with a corresponding second sealing surface of the second part, the first sealing surface including a spigot and the second sealing surface including a corresponding recess adapted to receive the spigot, in which the inside corner where the base of the spigot meets the first sealing surface is radiussed and the outside corner where the mouth of the recess meet the second sealing surface is correspondingly truncated so as to accommodate the radius and in which there is provided on either the radiussed inside corner or the truncated outside corner an integral projection which is deformable on assembly together of the parts to block leakage of pressure fluid along the path defined between the two corners.
The pressure fluid apparatus may comprise a positive displacement hydraulic machine of the kind hereinbefore referred to.
Preferably, in such a machine, the or each separate end cover is accurately located on the casing by means of a non-circular spigot formed on the cover, the spigot fitting directly into the adjacent ends of the overlapping bores in the casing. Preferably the spigot makes an interference fit therein.
Preferably, also, the spigot has an end profile which comprises portions of two overlapping circles smoothly interconnected by arcs to form a waisted shape approximating to a figure of eight.
A projection as defined in the fourth paragraph hereof is preferably disposed along the line where the spigot fits in each of the overlapping bores.
A positive displacement hydraulic machine will have two such paths between the radiussing and the truncation extending from the high pressure side to the low pressure side, and such a machine preferably has two such projections, whereby both paths are interrupted.
Preferably the two projections lie in the plane containing the axis of both of the overlapping bores.
A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings of which:
FIG. 1 is an end elevation of the open end of a gear pump casing with one integral end cover;
FIG. 2 is an enlargement of the area circled at 2 in FIG. 1;
FIG. 3 is a section on the line 3--3 in FIG. 1:
FIG. 4 is an end elevation of the inner face of
REFERENCES:
patent: 2460957 (1949-02-01), Whitfield
patent: 2923248 (1960-02-01), Hodgson
Peach Richard Guy
Sykes Jeremy Arthur
Wynn Barry
David Brown Hydraulics Limited
Vrablik John J.
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