US-12624693-B2 - Positive displacement roots blower noise suppression

US12624693B2US 12624693 B2US12624693 B2US 12624693B2US-12624693-B2

Abstract

A positive displacement roots blower can include a housing having an inlet structured to receive an incoming flow of a fluid, an outlet structured to receive an outgoing flow of the fluid, and a passage. The positive displacement roots blower can also include a pair of intermeshed rotating members supported for complementary rotation within the housing, where the rotating members and the housing form respective operating volumes there between which rotate with the rotating members. Each of the respective operating volumes has the following regions: (1) open to inlet/closed to outlet; (2) closed to inlet/closed to outlet; and (3) closed to inlet/open to outlet. The passage includes a restriction and connects to at least one of the operating volumes when the at least one of the respective operating volumes is in region (2). The restriction can be a venturi feedback connecting to the outlet.

Inventors

Michael J. Lucas
Gautier Lombart
Christian Doucet
Thomas Gholami-Zouj

Assignees

INGERSOLL-RAND INDUSTRIAL U.S., INC.

Dates

Publication Date: 20260512
Application Date: 20240724

Claims (20)

1 . A positive displacement roots blower comprising: a housing having: an inlet structured to receive an incoming flow of a compressible fluid, an outlet structured to exhaust an outgoing flow of the compressible fluid from the housing, a cavity defined by the housing, the cavity fluidly coupled to the inlet and the outlet, and a venturi feedback including a connecting tube, a venturi, and a venturi feedback inlet, the connecting tube in fluid communication with the outlet and the venturi, the connecting tube configured to divert a portion of the outgoing flow from the outlet the venturi feedback inlet in fluid communication with the venturi and the cavity, wherein the venturi defines a first chamber, a second chamber, and a constricted section formed therebetween, the first chamber and the second chamber having a flow-path cross-section that is larger than a flow-path cross-section of the connecting tube and the venturi feedback inlet, respectively; a pair of intermeshed rotors, where the rotors and housing form respective operating volumes there between which rotate with the rotors; and an air reservoir located proximate to the inlet for furnishing air to the operating volume; wherein the venturi feedback increases pressure inside the operating volumes prior to the rotors discharging the outgoing fluid through the outlet.
2 . The positive displacement roots blower of claim 1 , wherein each of the respective operating volumes have the following regions: open to the inlet/closed to the venturi feedback inlet/closed to the outlet; closed to the inlet/open to the venturi feedback inlet/closed to the outlet; and closed to the inlet/closed to the venturi feedback inlet/open to the outlet.
3 . The positive displacement roots blower of claim 1 , wherein the venturi feedback inlet is structured as an elongated entry to the respective operating volumes.
4 . The positive displacement roots blower of claim 3 , wherein the venturi feedback inlet is positioned between 100 degrees and 140 degrees from a 12 o'clock position.
5 . The positive displacement roots blower of claim 4 , wherein the region where the operating volume is closed to the inlet/open to the venturi feedback inlet/closed to the outlet occurs over an arc length of rotation of one of the intermeshed rotors of at least 35 degrees.
6 . The positive displacement roots blower of claim 5 , wherein the region where the operating volume is closed to the inlet/open to the venturi feedback inlet/closed to the outlet occurs over an arc length of rotation of one of the intermeshed rotors of at least 60 degrees.
7 . The positive displacement roots blower of claim 5 , wherein the operating volume is at a pressure equal to a static pressure in the outlet as the operating volume transitions from the region where the operating volume is closed to the inlet/open to the venturi feedback inlet/closed to the outlet to the region closed to the inlet/closed to the venturi feedback inlet/open to the outlet.
8 . The positive displacement roots blower of claim 1 , wherein the volume of the air reservoir is at least approximately equal to the volume of the operating volume to be filled.
9 . The positive displacement roots blower of claim 8 , wherein the volume of the air reservoir is greater than the volume of the operating volume to be filled.
10 . An apparatus comprising: a positive displacement roots blower having a pair of counter rotational rotors, each of the pair of counter rotational rotors having a plurality of respective lobes; an inlet structured to provide a compressible fluid to an intake side of the positive displacement roots blower; an outlet structured to discharge the compressible fluid from the positive displacement roots blower; and a pair of feedback loops having respective feedback loop inlets, venturis, and connecting tubes, the connecting tubes configured to divert a portion of the discharged compressible fluid from the outlet, the feedback loop inlets open to the positive displacement roots blower, the pair of feedback loops structured to increase a pressure between operating volumes between the plurality of lobes, each respective venturi defining a first chamber, a second chamber, and a constricted section formed therebetween, the first chamber and the second chamber having a flow-path cross-section that is larger than a flow-path cross-section of the respective connecting tube and the respective feedback loop inlet; and an air reservoir located proximate to the inlet for furnishing air to the operating volume; wherein each of the pair of counter rotational rotors rotates to a pressure equalization position in which adjacent lobes form a volume which is in fluid communication with a respective one of the pair of feedback loop inlets.
11 . The apparatus of claim 10 , wherein the feedback loops comprise a convergent-divergent passage having a throat, the throat forming a restriction.
12 . The apparatus of claim 10 , wherein the feedback loop inlets are in the form of elongate openings in the positive displacement roots blower, the elongate openings in fluid communication with the volume when each of the pair of counter rotational rotors are in the pressure equalization position.
13 . The apparatus of claim 12 , wherein the volume is formed over an angular range of motion of the adjacent lobes of at least 45 degrees.
14 . The apparatus of claim 13 , wherein the pressure equalization position of the adjacent lobes form the volume open to the feedback loop when a trailing lobe of the adjacent lobes traverses an angle between 5 and 15 degrees after the inlet is closed.
15 . The apparatus of claim 10 , wherein the volume of the air reservoir is at least approximately equal to the volume of the operating volume to be filled.
16 . A method of reducing pressure pulsation in a positive displacement roots blower comprising: rotating a first rotor of a pair of intermeshed first and second rotors associated with the positive displacement roots blower, the positive displacement roots blower having an inlet, an outlet, and a passage connected to the outlet; supplying a working fluid to a volume created between adjacent lobes of respective first and second rotors; increasing a pressure of the volume created between adjacent lobes of the first rotor when the first rotor passes a venturi feedback loop inlet connected to the passage; wherein a venturi having a venturi ingress, a constricted section, and a venturi egress, is disposed between the venturi feedback loop inlet and the passage, a connecting tube in fluid communication with the venturi ingress and the passage, the connecting tube diverting a portion of fluid from the passage, wherein the venturi ingress and the venturi egress have a flow-path cross-section that is larger than a flow-path cross-section of the connecting tube and the venturi feedback loop inlet, respectively.
17 . The method of claim 16 , wherein the inlet and the outlet are blocked by the adjacent lobes when the volume is in communication with the venturi feedback loop inlet connected to the outlet.
18 . The method of claim 16 , comprising rotating the first rotor through each of the following regions: open to the inlet/closed to the venturi feedback loop inlet/closed to the outlet; closed to the inlet/open to the venturi feedback loop inlet/closed to the outlet; and closed to the inlet/closed to the venturi feedback loop inlet/open to the outlet.
19 . The method of claim 18 , further comprising increasing the pressure of the volume created between adjacent lobes of the first rotor from atmospheric pressure when passing through the region open to the inlet/closed to the venturi feedback loop inlet/closed to the outlet to 1 bar atm when reaching the region closed to the inlet/closed to the venturi feedback loop inlet/open to the outlet.
20 . The method of claim 16 , further comprising positioning the venturi feedback loop inlet between 80 degrees and 140 degrees from a 12 o'clock position.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation of U.S. patent application Ser. No. 17/525,133 filed on Nov. 12, 2021, and titled “POSITIVE DISPLACEMENT ROOTS BLOWER NOISE SUPPRESSION”, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Ser. No. 63/112,981, filed Nov. 12, 2020, and titled “POSITIVE DISPLACEMENT ROOTS BLOWER NOISE SUPPRESSION”. U.S. patent application Ser. No. 17/525,133 and U.S. Provisional Application Ser. No. 63/112,981 are incorporated herein in their entireties. BACKGROUND Roots-type blowers, also referred to as roots blowers are positive displacement pumps that pump fluid through a pair of engaging rotors. DRAWINGS The Detailed Description is described with reference to the accompanying figures. The use of the same reference numbers in different instances in the description and the figures may indicate similar or identical items. FIG. 1 is a partial cross-sectional perspective view illustrating a positive displacement blower, with test points for a computational fluid dynamics (CFD) model for evaluating pressure overlayed on the blower. FIG. 2 is a partial cross-sectional perspective view illustrating a positive displacement roots blower having venturi feedbacks in accordance with examples of the present disclosure, where test points for a CFD model for evaluating pressure are overlayed on the roots blower. FIG. 3 is a graph illustrating mass flow in kilograms per second (kg/sec) versus angle in degrees showing a comparison of mass flow rates between the positive displacement blower illustrated in FIG. 1 and the positive displacement roots blower illustrated in FIG. 2, respectively. FIG. 4 is a graph illustrating pocket pressure in bars versus angle in degrees showing a comparison of pocket pressures between the positive displacement blower illustrated in FIG. 1 and the positive displacement roots blower illustrated in FIG. 2, respectively. FIG. 5 is a graph illustrating pressure pulsation in bars gage versus angle in degrees showing a comparison of inlet dynamic pressures at points P1_In′ and P1_In for the positive displacement blower illustrated in FIG. 1 and the positive displacement roots blower illustrated in FIG. 2, respectively. FIG. 6 is a graph illustrating pressure pulsation in bars gage versus angle in degrees showing a comparison of outlet dynamic pressures at points P1_Out′ and P1_Out for the positive displacement blower illustrated in FIG. 1 and the positive displacement roots blower illustrated in FIG. 2, respectively. FIG. 7 is a graph illustrating pressure pulsation in bars gage versus angle in degrees showing a comparison of outlet dynamic pressures at points P2_Out′ and P2_Out for the positive displacement blower illustrated in FIG. 1 and the positive displacement roots blower illustrated in FIG. 2, respectively. FIG. 8 is a graph illustrating pressure pulsation in bars gage versus angle in degrees showing a comparison of outlet dynamic pressures at points P3_Out′ and P3_Out for the positive displacement blower illustrated in FIG. 1 and the positive displacement roots blower illustrated in FIG. 2, respectively. FIG. 9 is a graph illustrating pressure pulsation in bars gage versus angle in degrees showing a comparison of outlet dynamic pressures at points P4_Out′ and P4_Out for the positive displacement blower illustrated in FIG. 1 and the positive displacement roots blower illustrated in FIG. 2, respectively. FIG. 10A is a diagrammatic illustration of pressure inside a pocket of a positive displacement roots blower, such as the positive displacement roots blower illustrated in FIG. 2, where a rotor is shown at an initial rotational orientation in accordance with examples of the present disclosure. FIG. 10B is a diagrammatic illustration of the pressure inside the pocket of the positive displacement roots blower of FIG. 10A, where the rotor is shown at a rotational orientation ten degrees (10°) from the initial rotational orientation. FIG. 10C is a diagrammatic illustration of the pressure inside the pocket of the positive displacement roots blower of FIG. 10A, where the rotor is shown at a rotational orientation twenty degrees (20°) from the initial rotational orientation. FIG. 10D is a diagrammatic illustration of the pressure inside the pocket of the positive displacement roots blower of FIG. 10A, where the rotor is shown at a rotational orientation thirty degrees (30°) from the initial rotational orientation. FIG. 10E is a diagrammatic illustration of the pressure inside the pocket of the positive displacement roots blower of FIG. 10A, where the rotor is shown at a rotational orientation forty degrees (40°) from the initial rotational orientation. FIG. 10F is a diagrammatic illustration of the pressure inside the pocket of the positive displacement roots blower of FIG. 10A, where the rotor is shown at a rotational orientation fifty degrees (50°) from the initial rotational orientation. FIG. 10G is a