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US 4,744,738 AGranted
Gear pump or motor with hard layer in interior casing surface
AssigneeShimadzu Corporation
InventorsMasayuki Miki, Kyoji Sera
Life of this patent
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Abstract
A gear pump or motor comprises a pair of gears intermeshing with each other, a case body accommodating the pair of gears, and a hard layer formed on an inner surface of the case body. The hard layer is made of a material to be as hard as not to be cut by tooth tips of the pair of gears. The hard layer may be a ceramic coating or a composite coating layer which performs a grinding like operation on the tooth tips.
Claims11
A high pressure gear pump or motor comprising:
- a casing having an internal cavity therein,
- a pair of intermeshing gears located in said cavity,
- a hard layer formed only on portions of said internal cavity,
- each of said gears having teeth with tips, a center portion and two ends,
- shaft means secured to each of said gears at said two ends thereof for supporting each of said gears in said cavity,
- said hard layer being made of a material harder than said gear teeth tips, each of said gears being shaped to have the diameter thereof become gradually smaller towards the central portion from both said ends by said hard layer grinding said tips of said gears when rotating, so as to make an appropriate clearance between said casing and said gears in operation to seal leakage of a fluid.
3 more elements
Dependencies are inferred from the claim text.