| 摘要 |
1,175,273. Gear pumps. PARKER-HANNIFIN CORP. May 11, 1967 [May 24, 1966], No. 22000/ 67. Heading F1F. A hydraulic gear pump comprising a housing 2, Fig.3, including front and rear covers 3, 4 and a centre section 5 having overlapping bores forming a pump cavity 8 in which intermeshing gears 9, 10 are rotatably mounted, includes passage means 55, Fig.4, in the cavity wall connected to the pump discharge chamber 16 to extend the high-pressure zone around the gears to provide adjacent each end thereof intermediate pressure zones and a flexible wear plate 31 having its inner face adjacent the gear faces and its outer face contacting seal means providing a chamber opposite to said high and intermediate pressure zones into which high-pressure fluid is introduced whereby the portion of the wear plate opposite the high-pressure zone is fluid-pressure balanced and the portion of the wear plate opposite each intermediate pressure zone is over-balanced so as to flex said portions into sealing engagement with the gears. The seal means comprises a resilient sealing member 37, a gasket 38 and a heat shield 39 with the sealing member having a continuous oval outer margin 40, Fig.6, and a pair of circular portions 41 inter-connected by a web 44 and connected to the margin 40 by radial webs 42, 43 and slotted radial webs 59, 60 to permit high-pressure fluid into chambers 35a, 35b, 35c up to the webs 42, 43. The webs 42, 43 separate these chambers from a chamber 36 connected to the pump low-pressure chamber 15. In the region of the low-pressure chamber 15, the pressures on either side of the wear plate 31 are in balance. In the regions "B" the pressures in the tooth spaces are gradually increasing whilst the pressure in the chamber 36 is uniform resulting in the tendency of the wear plate to flex away from the gears. In the regions "A" the pressures in the tooth spaces are still gradually increasing but are opposed by uniform high-pressure in the chambers 35b, 35c resulting in the wear plate being urged sealingly against the gears. Finally in the region of the passage means 55 the pressures on either side of the wear plate are again in balance. Thus sealing engagement between the wear plate and the gears occurs over a limited area to reduce friction and wear to a minimum. The wear plate may be laminated and may comprise a bronze face with a steel backing. |
