# US 2014/0193285 A1 · Optimized helix angle rotors for roots-style supercharger

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- Number: US 2014/0193285 A1
- Document ID: US20140193285A1
- Status: Published application
- Kind: A1
- Application number: 14/158,163
- Filed: 2014-01-17
- Published: 2014-07-10
- Earliest claimed: 2005-05-23
- Assignees: Eaton Corporation
- Applicants: Eaton Corporation
- Inventors: Matthew G. Swartzlander
- Web page: https://patentgrep.com/patent/US20140193285A1

## CPC

- F04C 18/18: with similar tooth forms (F04C18/16 takes precedence)
- F04C 18/084: {Toothed wheels}
- F04C 18/126: {with radially from the rotor body extending elements, not necessarily co-operating with corresponding recesses in the other rotor, e.g. lobes, Roots type}
- F04C 18/16: with helical teeth, e.g. chevron-shaped, screw type {(for non-parallel axes of movement F04C18/48)}
- F02B 33/38: of Roots type
- F04C 29/12: Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet
- F04C 2240/30: Casings or housings
- F04C 2250/20: of the rotor
- F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)

## Abstract

A Roots-type blower has first and second meshed, lobed rotors disposed in first and second chambers of a housing. Each lobe has first and second axially facing end surfaces defining a twist angle that is a function, at least partially, of the number of lobes on each rotor, and each lobe further defines a helix angle that is a function of the twist angle and an axial length between the first and second axially facing end surfaces of said lobe. The lobes cooperate with an adjacent surface of the housing to define at least one blowhole that defines a control volume, occurs in a cyclic manner, and moves linearly in a direction toward the outlet port. The blowhole provides communication between adjacent control volumes.

## Claims

### Claim at position 1

1-5. (canceled)

### Claim 6

An internally compressing Roots blower comprising:
a blower housing comprising a plurality of rotor chambers and a plurality of rotors;
wherein the rotors and the blower housing are configured to create internal fluid compression when the rotors are rotating at a first rotational speed and not to create internal fluid compression when the rotors are rotating at a second rotational speed.

### Claim 7 (depends on 6)

The internally compressing Roots blower of claim 6, including a plurality of cyclically occurring internal backflow passages.

### Claim 8 (depends on 7)

The internally compressing Roots blower of claim 7, wherein the plurality of cyclically occurring internal backflow passages are configured to permit a continuous backflow event.

### Claim 9 (depends on 7)

The internally compressing Roots blower of claim 7, wherein the cyclically occurring internal backflow passages are configured to move linearly in a direction toward an inlet port.

### Claim 10 (depends on 6)

The internally compressing Roots blower of claim 6, wherein the blower is configured to produce a boost ratio of at least 2.4 before reaching a critical temperature.

### Claim 11

A blower comprising
a blower housing; and
a plurality of rotors disposed in the blower housing;
wherein the blower housing and the rotors are configured to generate a plurality of cyclically occurring internal backflow passages configured to permit a continuous backflow event.

### Claim 12 (depends on 11)

The blower of claim 11, wherein the plurality of cyclically occurring internal backflow passages comprises at least three cyclically occurring internal backflow passages.

### Claim 13 (depends on 11)

The blower of claim 11, wherein the plurality of cyclically occurring internal backflow passages are configured to permit a continuous backflow event.

### Claim 14 (depends on 11)

The blower of claim 11, wherein the cyclically occurring internal backflow passages are configured to move linearly in a direction toward an inlet port.

### Claim 15 (depends on 11)

The blower of claim 11, wherein each of the plurality of rotors comprises a plurality of lobes, and wherein each of the plurality of lobes includes a maximum ideal twist angle that does not open a leak path between inlet and outlet ports of the blower housing.

### Claim 16 (depends on 15)

The blower of claim 15, wherein the maximum ideal twist angle is at least 170 degrees.

### Claim 17 (depends on 15)

The blower of claim 15, wherein each of the rotors includes a helix angle of about 29 degrees.

### Claim 18

A Roots blower comprising:
a plurality of rotors having a plurality of lobes; and
a blower housing comprising:
a plurality of rotor chambers,
an axial inlet port in a first end wall, and
a plurality of control volumes;
wherein the axial inlet port is in communication with four control volumes.

### Claim 19 (depends on 18)

The Roots blower of claim 18, wherein each of the plurality of control volumes is disposed between two adjacent unmeshed lobes of the plurality of lobes.

### Claim 20 (depends on 18)

The Roots blower of claim 18, wherein each of the plurality of control volumes corresponds to a trailing lobe and a leading lobe of the plurality of lobes.

### Claim 21 (depends on 20)

The Roots blower of claim 20, wherein the leading and trailing lobes corresponding to each of the plurality of control volumes are disposed between inlet and outlet cusps of the blower housing.

### Claim 22 (depends on 18)

The Roots blower of claim 18, comprising a plurality of cyclically occurring internal backflow passages.

### Claim 23 (depends on 22)

The Roots blower of claim 22, wherein the plurality of cyclically occurring internal backflow passages are configured to permit a continuous backflow event.

### Claim 24 (depends on 22)

The Roots blower of claim 22, wherein the cyclically occurring internal backflow passages are configured to move linearly in a direction toward an inlet port.

### Claim 25 (depends on 18)

The Roots blower of claim 18, wherein each of the plurality of rotors comprises a plurality of lobes, and wherein each of the plurality of lobes includes a maximum ideal twist angle that does not open a leak path between inlet and outlet ports of the blower housing.