Noise suppression system

Patent metadata

Field	Value
Publication number	US-9797412-B2
Application number	US-201615208268-A
Country	US
Kind code	B2
Filing date	Jul 12, 2016
Priority date	Mar 15, 2013
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A noise suppression system for an air-cooled internal combustion engine is disclosed. The system may include an acoustically designed shroud forming a cavity and configured for attenuating noise produced by a cooling air fan associated with the engine. In one system, the shroud is mountable on a housing of the air fan. A pair of air inlet passages may be provided which are operable to draw ambient cooling air into the shroud to the fan. The air inlet passages are acoustically configured and tuned to attenuate noise generated by the fan. In one system, the air inlet passages may each be formed in a rear quadrant of the shroud. Various configurations of the shroud may include quarter wave resonators and/or micro-perforated panels to further attenuate fan noise.

First claim

What is claimed is:

1. An internal combustion engine and noise suppression system comprising:
a cylinder of the internal combustion engine comprising at least one cooling fin;
a cooling air inlet passage;
an engine cooling fan that directs air through the cooling air inlet passage toward the at least one cooling fin;
a shroud positioned above and in fluid communication with the engine cooling fan, the shroud comprising a quarter wave resonator tuned to attenuate noise within a first range of frequencies generated by the engine cooling fan; and
a micro-perforated panel proximate the quarter wave resonator in the shroud, the micro-perforated panel tuned to attenuate the noise within a second range of frequencies.

2. The system according to claim 1 , wherein the quarter wave resonator is disposed in a downwardly open internal cavity of the shroud which is arranged adjacent to the engine cooling fan.

3. The system according to claim 1 , wherein the quarter wave resonator is disposed above the engine cooling fan.

4. The system according to claim 1 , wherein the quarter wave resonator is spaced vertically apart from the engine cooling fan.

5. The system according to claim 1 , wherein the quarter wave resonator comprises an array of cells, each cell of the array of cells having a depth, the depth selected to attenuate the noise within the first range of frequencies.

6. The system according to claim 5 , wherein the array of cells comprise a first group of cells having a first depth selected to attenuate the noise within the first range of frequencies, and a second group of cells having a second depth different than the first depth and selected to attenuate noise within a different range of frequencies.

7. The system according to claim 6 , wherein the shroud includes a top wall having a curved profile, the first group of cells being disposed in a central portion of the top wall and the second group of cells being disposed in peripheral portions of the top wall.

8. The system according to claim 1 , wherein the micro-perforated panel comprises a smooth sheet of material having a plurality of holes of a predetermined diameter and pitch.

9. The system according to claim 8 , wherein a first array of the holes have a first diameter to attenuate noise generated by the engine cooling fan within the second range of frequencies; and a second array of the holes have a second diameter different than the first diameter to attenuate noise generated by the engine cooling fan within a third second range of frequencies.

10. The system according to claim 1 , wherein the micro-perforated panel divides an internal cavity of the shroud into a top cavity and a bottom cavity.

11. The system according to claim 10 , wherein the quarter wave resonator is disposed in the top cavity.

12. An internal combustion engine and noise suppression system comprising:
a cylinder of the internal combustion engine comprising at least one cooling fin;
a cooling air inlet passage;
an engine cooling fan that directs air through the cooling air inlet passage toward the at least one cooling fin; and
a shroud in fluid communication with the engine cooling fan and including a top wall which forms a part of the cooling air inlet passage, the shroud comprising a first micro-perforated panel of uniform thickness comprising a plurality of holes tuned to attenuate noise within a first range of frequencies generated by the engine cooling fan;
wherein the first micro-perforated panel is arranged in a first horizontal plane above the engine cooling fan and divides an internal cavity of the shroud into a top cavity above the first micro-perforated panel between the top wall of the shroud and first micro-perforated panel, and a bottom cavity between the engine cooling fan and first micro-perforated panel;
wherein the top cavity has depth measured from the top wall of the shroud to the first micro-perforated panel that is tuned to provide wave cancellation of noise within the first range of frequencies.

13. The system according to claim 12 , wherein the first micro-perforated panel is disposed in a downwardly open internal cavity of the shroud which is arranged adjacent to the engine cooling fan.

14. The system according to claim 12 , wherein a first array of holes have a first diameter to attenuate noise generated by the engine cooling fan within the first range of frequencies, and a second array of holes have a second diameter different than the first diameter to attenuate noise generated by the engine cooling fan within a second range of frequencies.

15. The system according to claim 12 , further comprising a second micro-perforated panel disposed in the shroud proximate the first micro-perforated panel, the second micro-perforated panel tuned to attenuate noise generated by the engine cooling fan within a second range of frequencies.

16. An internal combustion engine and noise suppression system comprising:
the internal combustion engine comprising a cylinder;
an engine cooling fan associated with the engine, the engine cooling fan operable to direct cooling air downwards towards the engine to dissipate heat generated by the engine;
an air passage disposed above the engine and in fluid communication with the engine cooling fan;
a noise suppression device arranged in the air passage, the noise suppression device arranged to intercept and attenuate noise within a first range of frequencies generated by the engine cooling fan;
wherein the noise suppression device comprises a planar micro-perforated panel including a smooth sheet of material having a plurality of holes of a predetermined diameter and pitch, the micro-perforated panel tuned to attenuate noise within a first range of frequencies generated by the engine cooling fan;
wherein the noise suppression device further comprises a quarter wave resonator including a plurality of cells each having a depth, the quarter wave resonator tuned to attenuate noise within a first range of frequencies generated by the engine cooling fan.

Assignees

• Kohler Co

Inventors

• Le Roy Tyler W
• Bykowski Jonathan T
• Albert Roger W

Classifications

• F01P5/02

  Pumping cooling-air; Arrangements of cooling-air pumps, e.g. fans or blowers · CPC title

• F04D29/4213

  suction ports · CPC title

• F04D29/424

  Double entry casings · CPC title

• F02F1/065

  with means for directing or distributing cooling medium · CPC title

• F04D17/16

  for displacing without appreciable compression · CPC title