Hitachi, Ltd.

Toshiaki Nagai

Shigeru Sasaki

Katsuhiko Kasuya

A nonlubricated screw fluid machine comprising a pair of rotors including a male and a female screw rotors provided with a dual lead tooth profile on the basis of the difference in the temperature between the outlet side and the inlet side when forming a tapered rotors considering the temperature distribution within the rotors in which each of the shape of the male and female rotors after the thermal expansion is employed as a basic tooth profile.

Non-lubricated screw machine with a rotor having a taper and varied

A nonlubricated screw fluid machine comprising a pair of rotors including male and female screw rotors provided with a dual lead tooth profile on the basis of the difference in the temperature between the outlet side and the inlet side when forming tapered rotors considering the temperature distribution within the rotors in which each of the shape of the male and female rotors after the thermal expansion is employed as a basic tooth profile.

Nonlubricated screw fluid machine

A screw fluid machine comprising female and male rotors each including foward and backward flanks each having a reference profile, respectively, wherein on at least one of the forward and backward flanks of the female and male rotors a modified profile is obtained by appropriately angularly shifting the reference profile around a center of the associated rotor to provide proper backlash between the engaged rotors.

Rotors for a screw fluid machine

A screw rotor tooth profile which comprises a pair of male and female rotor tooth profiles engaging each other. The screw rotor tooth profile is configured such that at least one of the male and female rotor tooth profiles has a point of minimum pressure angle or an engaging tooth surface concurring with those of a theoretical tooth profile and is deviated from the theoretical tooth profile such that the amount of deviation increases as going from the point of minimum pressure angle or the engaging tooth surface toward the tooth top side and the tooth bottom side. The screw rotor tooth profile, even in case of the presence of machining and/or assembling errors in the profiles, are capable of assuring excellent mutual tooth engagement therebetween and almost not susceptible to that or those errors, that is, insensitive to manufacturing precision.

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Shimizu, Japan

Toshiaki Nagai