Method and apparatus for reducing noise in a roots-type blower
First Claim
1. A noise reducing configuration for a Roots-type blower comprising:
- a housing defining a rotor chamber, said rotor chamber comprising having an inlet and an outlet;
a first and a second rotor rotatably mounted in said chamber, each rotor defining a plurality of lobes, adjacent lobes of each rotor cooperating with said housing to define at one or more times gas transport chambers, said rotors configured to move gas from said inlet via said gas transport chamber to said outlet; and
at least one outlet gas flow channel extending from said outlet along an inner surface of said housing at said rotor chamber in a direction opposite a direction of rotation of said rotor, said at least one outlet gas flow channel configured to permit gas to flow from said outlet into a gas transport chamber as said lobes of said rotor rotate towards said outlet, said at least one outlet gas flow channel configured so that a pressure of said gas in said chamber as said chamber moves towards said outlet changes at an approximately linear rate.
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Accused Products
Abstract
A Roots-type blower comprises a housing defining a rotor chamber and an inlet and outlet to the rotor chamber. First and second rotors are mounted in the rotor chamber, each rotor defining a plurality of lobes, adjacent lobes and the housing cooperating to define gas transport chambers. The blower is configured so that a net flow rate of gas into a gas transport chamber is generally or approximately constant, whereby a change in gas pressure in the gas transport chamber is generally or approximately linear, as the gas transport chamber approaches the outlet. In one embodiment, this is accomplished by providing flow channels extending from the outlet towards the inlet, and from the inlet towards the outlet, corresponding to each rotor. The flow channels permit gas to flow from the high pressure outlet to a gas transport chamber and from the gas transport chamber to the low pressure inlet. The resulting amelioration of pressure spikes associated with flow back substantially reduces the operational noise level of the blower.
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Citations
70 Claims
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1. A noise reducing configuration for a Roots-type blower comprising:
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a housing defining a rotor chamber, said rotor chamber comprising having an inlet and an outlet;
a first and a second rotor rotatably mounted in said chamber, each rotor defining a plurality of lobes, adjacent lobes of each rotor cooperating with said housing to define at one or more times gas transport chambers, said rotors configured to move gas from said inlet via said gas transport chamber to said outlet; and
at least one outlet gas flow channel extending from said outlet along an inner surface of said housing at said rotor chamber in a direction opposite a direction of rotation of said rotor, said at least one outlet gas flow channel configured to permit gas to flow from said outlet into a gas transport chamber as said lobes of said rotor rotate towards said outlet, said at least one outlet gas flow channel configured so that a pressure of said gas in said chamber as said chamber moves towards said outlet changes at an approximately linear rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A noise reducing configuration for a Roots-type blower comprising:
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a housing defining a rotor chamber, said rotor chamber having an inlet and an outlet;
a first and a second rotor rotatably mounted in said chamber, each rotor defining a plurality of lobes, adjacent lobes of each rotor cooperating with said housing to define at one or more times gas transport chambers, said rotors configured to move gas from said inlet via said gas transport chamber to said outlet; and
at least one outlet gas flow channel extending from said outlet along an inner surface of said housing in a direction opposite a direction of rotation of said rotor, said at least one outlet gas flow channel configured to permit gas to flow from said outlet into a gas transport chamber as said lobes of said rotor rotate towards said outlet, said at least one outlet gas flow channel configured so that a gas flow rate from said outlet into said gas transport chamber is approximately constant. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A noise reducing configuration for a Roots-type blower comprising:
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a housing defining a rotor chamber, said rotor chamber having an inlet and an outlet;
a first and a second rotor rotatably mounted in said chamber, each rotor defining a plurality of lobes, adjacent lobes of each rotor cooperating with said housing to define at one or more times gas transport chambers, said rotors configured to move gas from said inlet via said gas transport chambers to said outlet; and
at least one outlet gas flow channel extending from said outlet along an inner surface of said housing in a direction opposite to a direction of rotation of said rotor, said at least one outlet gas flow channel configured to permit gas to flow from said outlet into a gas transport chamber as said lobes of said rotor rotate towards said outlet, said at least one outlet gas flow channel defining a flow area which increases generally non-linearly towards the direction of said outlet. - View Dependent Claims (20, 21, 22, 23, 24)
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25. A noise reducing configuration for a Roots-type blower comprising:
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a housing defining a rotor chamber, said rotor chamber having an inlet and an outlet;
a first and a second rotor rotatably mounted in said chamber, each rotor defining a plurality of lobes, adjacent lobes of each rotor cooperating with said housing to define at one or more times gas transport chambers, said rotors configured to move gas from said inlet via said gas transport chambers to said outlet;
at least one outlet gas flow channel corresponding to said first rotor, said at least one outlet gas flow channel extending from said outlet along an inner surface of said housing in a direction opposite a direction of rotation of said first rotor, said at least one outlet gas flow channel configured to permit gas to flow from said outlet into a gas transport chamber between two lobes of said first rotor as said lobes of said first rotor rotate towards said outlet;
at least one outlet gas flow channel corresponding to said second rotor, said at least one outlet gas flow channel extending from said outlet along an inner surface of said housing in a direction opposite a direction of rotation of second first rotor, said at least one outlet gas flow channel configured to permit gas to flow from said outlet into a gas transport chamber between two lobes of said second rotor as said lobes of said second rotor rotate towards said outlet;
at least one inlet gas flow channel corresponding to said first rotor, said at least one inlet gas flow channel extending from said inlet along an inner surface of said housing at said rotor chamber in a direction of rotation of said first rotor, said at least one inlet gas flow channel configured to permit gas to flow from said gas transport chamber between two lobes of said first rotor back to said inlet as said lobes of said first rotor rotate towards said outlet; and
at least one inlet gas flow channel corresponding to said second rotor, said at least one inlet gas flow channel extending from said inlet along an inner surface of said housing at said rotor chamber in a direction of rotation of said second rotor, said at least one inlet gas flow channel configured to permit gas to flow from said gas transport chamber between two lobes of said second rotor back to said inlet as said lobes of said second rotor rotate towards said outlet. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A method for configuring a gas flow path for providing a flow of gas between a port of a Roots-type blower and a gas transport chamber formed between lobes of at least one rotor of said blower, comprising the steps of:
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selecting a length for said flow path;
selecting a desired gas transport chamber function that defines desired values of a characteristic of gas in said gas transport chamber as a function of rotor position;
selecting an area function that defines a cross-sectional area of said flow path along said length of said flow path;
calculating estimated values of said characteristic of said gas in said gas transport chamber corresponding to said area function;
comparing said estimated values to said desired values;
repeating said steps of selecting an area function, calculating estimated values, and comparing said estimated values to said desired values until said estimated values are approximately equal to said desired values. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55)
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56. A method for configuring a gas flow path for providing a flow of gas between a port of a Roots-type blower and a gas transport chamber formed between lobes of at least one rotor of said blower, comprising the steps of:
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selecting a length for said flow path;
selecting a desired gas transport chamber function that defines desired values of a characteristic of gas in said gas transport chamber as a function of rotor position;
selecting an initial incremental rotor position;
calculating an initial desired cross-sectional flow area corresponding to said gas transport chamber function at said initial incremental rotor position;
selecting a succeeding incremental rotor position;
calculating a succeeding desired cross-sectional flow area corresponding to said gas transport chamber function at said succeeding incremental rotor position;
repeating said steps of selecting a succeeding incremental rotor position and calculating a succeeding desired cross-sectional flow area for rotor positions traversing said length of said flow path. - View Dependent Claims (57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70)
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Specification