Roots-style blower with leakage mechanisms

Patent metadata

Field	Value
Publication number	US-9617998-B2
Application number	US-201414535831-A
Country	US
Kind code	B2
Filing date	Nov 7, 2014
Priority date	Nov 8, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

The disclosure concerns a Roots-type blower comprising a housing defining first and second transversely overlapping cylindrical chambers and at least one inlet port and an outlet port; first and second meshed, lobed rotors, each lobe having a top land sealingly cooperating with the cylindrical chambers; a plurality of control volumes for transfer of fluid, each control volume being defined by a pair of adjacent lobes on one of the rotors, and at least one of the cylindrical chambers; and blowholes formed within the cylindrical chambers in connection with meshing of the lobes of the first and second rotors. The blower further comprises at least one backflow slot extending through the housing wall of each cylindrical chamber for effecting a leakage of fluid from downstream the at least one outlet port into a control volume.

First claim

What is claimed is:

1. A Roots-type blower comprising:
a housing defining first and second transversely overlapping cylindrical chambers, the housing comprising a first end wall and a second end wall, and the housing defining at least one inlet port in the first end wall and at least one outlet port at an intersection of the first and second chambers, adjacent the second end wall;
first and second meshed, lobed rotors disposed, respectively, in the first and second cylindrical chambers, each rotor including a plurality of lobes, each lobe having first and second axially facing end surfaces sealingly cooperating with the first and second end walls, respectively, and a top land sealingly cooperating with a respective cylindrical chamber, each lobe having its first and second axially facing end surfaces defining a twist angle of at least 90°, and each lobe defining a helix angle;
a plurality of control volumes for transfer of fluid from the at least one inlet port to the at least one outlet port, each control volume being defined by a pair of adjacent lobes on one of the rotors, and at least one of the cylindrical chambers, the first end wall, or the second end wall;
a leakage mechanism for effecting a leakage of fluid between adjacent control volumes, the leakage mechanism including blowholes formed within the cylindrical chambers in connection with meshing of the lobes of the first and second rotors; and
an additional leakage mechanism comprising at least two individual backflow slots provided on each side of a center line of the housing, each backflow slot extending through a wall of the housing for effecting a leakage of fluid from downstream of the at least one outlet port into a control volume prior to traversal of boundaries of the at least one outlet port by the top land of a lead lobe of the control volume, wherein the individual backflow slots on either side of the center line are arranged along a slot axis having a slot axis angle to a longitudinal direction of the housing, and wherein the slot axis angle is smaller than the helix angle of the lobes, such that the individual backflow slots along each slot axis sequentially enable a fluid flow passage to a control volume as the top land of the lead lobe of the control volume progressively traverses the slot axis.

2. The Roots-type blower according to claim 1 wherein the additional leakage mechanism comprises at least three individual backflow slots provided on each side of the center line of the housing.

3. The Roots-type blower according to claim 1 wherein each backflow slot has a rectangular shape.

4. The Roots-type blower according to claim 1 wherein each backflow slot has an elongated shape having a length in the range of 3-25 millimeters.

5. The Roots-type blower according to claim 1 wherein each backflow slot has an elongated shape having a length in the range of 4-20 millimeters.

6. The Roots-type blower according to claim 1 wherein each backflow slot is provided on either side of the at least one outlet port.

7. The Roots-type blower according to claim 1 wherein the housing comprises a reinforcing rib projecting outwardly from an exterior surface of the housing and extending in a direction perpendicular to a longitudinal direction, and the at least two individual backflow slots provided on each side of the center line are provided on each side of the reinforcing rib.

8. The Roots-type blower according to claim 1 wherein a blowhole between adjacent control volumes is formed in regions along a longitudinal direction of the blower when the lobe of any rotor is located between an angular position where the top land has passed an outlet cusp and an angular position where the lobe sealingly closes the control volume upon meshing with lobes of the other rotor.

9. A Roots-type blower comprising:
a housing defining first and second transversely overlapping cylindrical chambers, the housing comprising a first end wall and a second end wall, and the housing defining at least one inlet port in the first end wall and at least one outlet port at an intersection of the first and second chambers, adjacent the second end wall;
first and second meshed, lobed rotors disposed, respectively, in the first and second cylindrical chambers, each rotor including a plurality of lobes, each lobe having first and second axially facing end surfaces sealingly cooperating with the first and second end walls, respectively, and a top land sealingly cooperating with a respective cylindrical chamber, each lobe having its first and second axially facing end surfaces defining a twist angle and each lobe defining a helix angle;
a plurality of control volumes for transfer of fluid from the at least one inlet port to the at least one outlet port, each control volume being defined by a pair of adjacent lobes on one of the rotors, and at least one of the cylindrical chambers, the first end wall, or the second end wall; and
a leakage mechanism for effecting a leakage of fluid between adjacent control volumes, the leakage mechanism comprising at least one bleed recess provided in the second end wall, wherein the at least one bleed recess provides a passage between the second axially facing end surface of a lobe and the second end wall such that fluid is enabled to leak between adjacent control volumes, and wherein the at least one bleed recess is located to enable a leakage of fluid between adjacent control volumes only after each of the adjacent control volumes is lacking fluid communication with the at least one inlet port.

10. The Roots-type blower according to claim 9 wherein at least two bleed recesses are provided in the second end wall, and wherein at least one bleed recess is associated with each individual cylindrical chamber.

11. The Roots-type blower according to claim 10 wherein each of the at least two bleed recesses has an angular width greater than an angular width of a lobe.

12. The Roots-type blower according to claim 9 wherein the twist angle of each lobe is at least 120°.

13. The Roots-type blower according to claim 9 wherein the twist angle of each lobe is at least 140°.

14. The Roots-type blower according to claim 9 wherein the twist angle of each lobe is less than 360°.

15. The Roots-type blower according to claim 9 wherein the twist angle of each lobe is less than 300°.

16. The Roots-type blower according to claim 9 wherein the twist angle of each lobe is less than 240°.

17. A Roots-type blower comprising:
a housing defining first and second transversely overlapping cylindrical chambers, the housing comprising a first end wall and a second end wall, and the housing defining at least one inlet port and at least one outlet port;
first and second meshed, lobed rotors disposed, respectively, in the first and second cylindrical chambers, each rotor including a plurality of lobes, each lobe having first and second axially facing end surfaces sealingly cooperating with the first and second end walls, respectively, and a top land sealingly cooperating with a portion of the housing that defines a respective cylindrical chamber, each lobe having its first and second axially facing end surfaces defining a twist angle of at least 90°, and each lobe defining a helix angle;
a plurality of control volumes for transfer of fluid from the at least one inlet port to the at least one outlet port, each control volume being at least partially defined by a pair of adjacent lobes on one of the rotors;
a leakage mechanism for effecting a leakage of fluid between adjacent control volumes, the leakage mechanism including blowholes formed within the c

Assignees

• Volvo Car Corp

Inventors

• Knutsson Magnus
• Ohlson Anders
• Burenius Ragnar
• Brunberg Johan
• Toma Amir

Classifications

• F04C18/107

  with helical teeth · CPC title

• F04C15/06

  Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet · CPC title

• F04C29/122 Primary

  Arrangements for supercharging the working space (similar arrangements for internal combustion engines F02B33/00, F02B37/00) · CPC title

• F04C15/0026

  Elements specially adapted for sealing of the lateral faces of intermeshing-engagement type machines or pumps, e.g. gear machines or pumps · CPC title

• F04C18/126

  with radially from the rotor body extending elements, not necessarily co-operating with corresponding recesses in the other rotor, e.g. lobes, Roots type · CPC title