Screw pump, screw rotor, method of manufacturing a screw rotor, and use of a screw pump or a screw rotor

Patent metadata

Field	Value
Publication number	US-2024328419-A1
Application number	US-202218576066-A
Country	US
Kind code	A1
Filing date	Jul 5, 2022
Priority date	Jul 8, 2021
Publication date	Oct 3, 2024
Grant date	—

Abstract

A screw pump comprising a housing defining a chamber and two screw rotors. Wherein each screw rotor comprises a rotor shaft and at least two displacement elements connected with the rotor shaft. Each displacement element having at least one helical protrusion. One of the displacement elements is a suction-side displacement element arranged in a suction-side section of the chamber. Another one of the displacement elements is a pressure-side displacement element arranged in a pressure-side section of the chamber. The suction-side displacement element is designed tapering in the conveying direction. The clearance between the pressure-side displacement element and the pressure-side section of the chamber at least partly decreases in the conveying direction. Furthermore, a screw rotor, a method of manufacturing a screw rotor and a use of a screw pump or a screw rotor.

First claim

1 . Screw pump, preferably screw vacuum pump, more preferably dry running screw vacuum pump, comprising a housing comprising a wall, the housing defining a chamber and two screw rotors,
wherein each screw rotor comprises:
a rotor shaft, and
at least two displacement elements connected with the rotor shaft, each displacement element having at least one helical protrusion,
wherein one of the displacement elements is a suction-side displacement element arranged in a suction-side section of the chamber, and
wherein another one of the displacement elements is a pressure-side displacement element arranged in a pressure-side section of the chamber,
wherein the suction-side displacement element is designed tapering in the conveying direction, and
wherein the clearance between the pressure-side displacement element and the pressure-side section of the chamber at least partly decreases in the conveying direction.

2 . Screw pump of claim 1 , wherein the clearance between the pressure-side displacement element and the pressure-side section of the chamber is adjusted such that during operation, particularly during operation in the 100-300 mbar region, a uniform gap between the between the pressure-side displacement element and the pressure-side section of the chamber is formed.

3 . Screw pump of claim 1 , wherein the diameter of the pressure-side displacement element increases in the conveying direction.

4 . Screw pump of claim 1 , wherein the pressure-side displacement element is designed counter-conical to the suction-side displacement element.

5 . Screw pump of claim 1 , wherein the clearance between the pressure-side displacement element and the pressure-side section of the chamber at least partly decreases linearly in the conveying direction.

6 . Screw pump of claim 1 , wherein the clearance between the pressure-side displacement element and the pressure-side section of the chamber decreases by 10% to 50%, particularly by 15% to 30% in the conveying direction.

7 . Screw pump of claim 1 , wherein the diameter of the at least one helical protrusion of the pressure-side displacement element increases in the conveying direction.

8 . Screw pump of claim 7 , wherein the diameter of the at least one helical protrusion of the pressure-side displacement element increases by 0.05% to 0.5%, particularly by 0.05% to 0.2% in the conveying direction.

9 . Screw pump of claim 1 , wherein the inner diameter of the pressure-side section of the chamber decreases in the conveying direction.

10 . Screw pump of claim 1 , wherein the inner volume ratio of the screw pump is at least 4, particularly at least 7.

11 . Screw pump of claim 1 , wherein the suction-side displacement element has a volume ratio of at least 4, particularly at least 7.

12 . Screw pump of claim 1 , wherein the pressure-side displacement element has a volume ratio of 1 to 3, particularly of 1.0001 to 1.1.

13 . Screw pump of claim 1 , wherein the diameter of an inner element of the suction-side displacement element increases in the conveying direction.

14 . Screw pump of claim 1 , wherein the diameter of an inner element of the pressure-side displacement element is essentially constant.

15 . Screw pump of claim 1 , wherein each displacement element has at least one helical recess.

16 . Screw pump of claim 15 , wherein the volume of the helical recess of the suction-side displacement element is greater than the volume of the helical recess of the pressure-side displacement element.

17 . Screw pump of claim 1 , wherein a further displacement element is provided that is arranged upstream of the suction-side displacement element in the conveying direction, the further displacement element being preferably substantially cylindrical in shape.

18 . Screw rotor for a screw pump, preferably for a screw vacuum pump, more preferably for a dry running screw vacuum pump, comprising:
a rotor shaft, and at least two displacement elements connected with the rotor shaft, each displacement element having at least one helical protrusion,
wherein one of the displacement elements is a suction-side displacement element, and
wherein another one of the displacement elements is a pressure-side displacement element,
wherein the suction-side displacement element is designed tapering in the conveying direction, and
wherein the diameter of the pressure-side displacement element increases in the conveying direction.

19 . Method of manufacturing a screw rotor for a screw pump, preferably for a screw vacuum pump, more preferably for a dry running screw vacuum pump, comprising the steps of:
providing a screw rotor, the screw rotor comprising a rotor shaft, and at least two displacement elements connected with the rotor shaft, each displacement element having at least one helical recess, wherein one of the displacement elements is a suction-side displacement element, wherein the suction-side displacement element is designed tapering in the conveying direction, wherein another one of the displacement elements is a pressure-side displacement element, wherein the pressure-side displacement element is designed substantially cylindrically; and machining the pressure-side displacement element to have an increasing diameter in the conveying direction.

20 . Method of claim 19 , wherein the machining is performed by means of turning, and/or milling, and/or grinding.

21 . Use of a screw pump as defined in claim 1 to generate a vacuum, or a screw rotor as defined in claim 18 in a screw pump, preferably in a screw vacuum pump, more preferably in a dry running screw vacuum pump, to generate a vacuum.

Assignees

• Leybold Gmbh

Inventors

• Müller Roland Albert
• Chrisp David Thomas

Classifications

• F04C2270/17

  Tolerance; Play; Gap · CPC title

• F04C2230/602

  Gap; Clearance · CPC title

• F04C2230/10

  by removing material · CPC title

• F04C25/02

  for producing high vacuum (sealing arrangements F04C27/00; silencing F04C29/06) · CPC title

• F04C23/005

  of dissimilar working principle · CPC title