RING GEAR AND METHOD FOR MANUFACTURING RING GEAR
First Claim
1. A ring gear that, together with a sun gear and a pinion gear that is disposed radially outward of the sun gear and meshes with the sun gear, forms a planetary gear unit, the ring gear comprising:
- a body,internal teeth that are configured to mesh with the pinion gear and that are formed in at least a part of an inner peripheral surface of the body, andexternal teeth that have a lower hardness than the internal teeth and that are formed in at least a part of an outer peripheral surface of the body,wherein a surface nitrogen concentration in the internal teeth is higher than that in at least tooth surfaces of the external teeth.
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Accused Products
Abstract
A ring gear that, together with a sun gear and a pinion gear that is disposed radially outward of the sun gear and meshes with the sun gear, forms a planetary gear unit, the ring gear includes: a body, internal teeth that are configured to mesh with the pinion gear and that are formed in at least a part of an inner peripheral surface of the body, and external teeth that have a lower hardness than the internal teeth and that are formed in at least a part of an outer peripheral surface of the body, wherein a surface nitrogen concentration in the internal teeth is higher than that in at least tooth surfaces of the external teeth.
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Citations
5 Claims
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1. A ring gear that, together with a sun gear and a pinion gear that is disposed radially outward of the sun gear and meshes with the sun gear, forms a planetary gear unit, the ring gear comprising:
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a body, internal teeth that are configured to mesh with the pinion gear and that are formed in at least a part of an inner peripheral surface of the body, and external teeth that have a lower hardness than the internal teeth and that are formed in at least a part of an outer peripheral surface of the body, wherein a surface nitrogen concentration in the internal teeth is higher than that in at least tooth surfaces of the external teeth. - View Dependent Claims (2)
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3. A method for manufacturing a ring gear having internal teeth in an inner peripheral surface and external teeth in a outer peripheral surface from an annular raw blank, comprising the steps of:
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forming an intermediate body by forming the internal teeth in an inner peripheral surface of the annular raw blank; forming a nitride layer at a surface of the intermediate body by nitriding an entirety of the intermediate body; removing the nitride layer formed in a part of an outer peripheral surface of the intermediate body resulting from the nitriding, which is a part where formation of the external teeth is desired; and forming the external teeth in a part of the intermediate body from which the nitride layer has been removed and where formation of the external teeth is desired. - View Dependent Claims (4, 5)
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Specification