Pipe joints or couplings – With leakage or drip disposal
Patent
1998-10-02
2000-06-13
Nicholson, Eric K.
Pipe joints or couplings
With leakage or drip disposal
285190, 2851233, F16L 3904
Patent
active
060739703
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a rotary joint for the transfer of pressurised working fluid from a stationary to a rotating machine part and/or vice versa, comprising a housing associated with the stationary machine part, a shaft associated with the rotating machine part, which shaft extends in the housing and optionally also therethrough, and at least one bush accommodated in the housing, which bush tightly surrounds the shaft and is mounted sealedly in the housing in such a way as to be radially resiliently movable, the inner surface of the bush and the circumferential surface of the shaft being provided with sealing faces which slide against each other, and the bush comprising at least one radial bore which is connected, via an annular channel encircling the circumferential surface of the shaft and/or the inner surface of the bush, with at least one radial bore in the shaft for conveying pressurised working fluid through the bore in the bush to a fluid duct which extends axially in the shaft and is connected with the radial bore in the shaft.
Such a rotary joint is known, for example, from German Offenlegungsschrift No. 38 06 931. In the case of the known rotary joint, it is a question of so improving a rotary joint with radial gap that said rotary joint operates absolutely reliably under all operating conditions, especially at high speeds and simultaneous high pressures and additionally exhibits the lowest possible degree of leakage. This is achieved by radially displaceable mounting of the bush, whereby manufacturing tolerances and possible vibrations or deviations from the concentric position of the two sliding sealing faces may be compensated without excessive friction occurring between the sliding sealing faces. Although the interposition of the bush, which is mounted radially resiliently and simultaneously sealedly in the housing, makes it possible to increase the rotational speeds and/or diameter of the rotary joints without excessive leakage losses, in many instances of use such rotary joints still remain a speed- and/or shaft diameter-restricting element. With the known solution, it is impossible to achieve reliable, low-friction operation without seizing and with a simultaneously low leakage rate in particular when the operating pressure is not constant, but rather varies between high and lower values. For this reason, there has also in some cases been a move towards the repositioning of corresponding rotary joints onto a shaft extension portion or end, for example, which does not transmit torque and is only slightly loaded and which may accordingly be provided with a tapered diameter. However, the problem then arises of appropriately positioning the ducts extending axially in the shaft or of effecting connection with the axially extending duct portions in the shaft extension zone. The shaft or the rotating machine part thereby becomes substantially more complex. Moreover, from time to time it is necessary to effect transmission of the working fluid in a torque-transmitting shaft portion with a correspondingly large diameter.
In the case of such rotary joints, the so-called sliding sealing faces between shaft and bush are also not provided for the purpose of actually sliding frictionally on each other, but rather there should if possible be provided between these ideally concentric, cylindrical sealing faces a very narrow but uniform gap through which working fluid or lubricant passes and through which there flows as slight as possible a leakage flow. The narrower this gap, however, the more likely it is that direct contact between shaft and bush will arise and, in the worst case, seizing thereof. With larger gap widths, on the other hand, large leakage losses arise, which are no longer acceptable, especially with high pressures and large shaft diameters.
With respect to this prior art, the object of the present invention is to provide a rotary joint with the above-mentioned features, which permits a further increase in shaft diameter, in the relative speeds of the surfaces sliding against e
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Gernand Georg
Ott Stephan
GAT Gesellschaft Fur Antriebstechnik mbH
Nicholson Eric K.
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