Screw pump with a tapered suction-side section and a pressure-side section with a decreasing clearance

Patent metadata

Field	Value
Publication number	US-12378961-B2
Application number	US-202218576066-A
Country	US
Kind code	B2
Filing date	Jul 5, 2022
Priority date	Jul 8, 2021
Publication date	Aug 5, 2025
Grant date	Aug 5, 2025

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

The invention claimed is:

1. A screw 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 a 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. The screw pump of claim 1 , wherein the clearance between the pressure-side displacement element and the pressure-side section of the chamber is such that during operation in the 100-300 mbar region, a gap between the between the pressure-side displacement element and the pressure-side section of the chamber is formed.

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

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

5. The 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. The 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%, in the conveying direction.

7. The 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. The 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% in the conveying direction.

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

10. The screw pump of claim 1 , wherein an inner volume ratio of the screw pump is at least 4.

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

12. The screw pump of claim 1 , wherein the pressure-side displacement element has a volume ratio of 1 to 3.

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

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

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

16. The 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. The 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 substantially cylindrical in shape.

18. A screw rotor for a screw 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 a conveying direction, and
wherein the diameter of the pressure-side displacement element increases in the conveying direction.

19. A method of manufacturing a screw rotor for a screw pump comprising:
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 a 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. The method of claim 19 , wherein the machining is performed by means of turning, and/or milling, and/or grinding.

21. A method of manufacturing a screw pump comprising:
providing a screw rotor comprising at least two displacement elements, wherein one of the displacement elements is a suction-side displacement element, wherein the suction-side displacement element is designed tapering in a conveying direction, wherein another one of the displacement elements is a pressure-side displacement element;
machining the pressure-side displacement element to have an increasing diameter in the conveying direction; and
arranging the screw rotor inside a housing.

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