Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
  • F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
  • F04D29/663—Sound attenuation
  • F04D29/664—Sound attenuation by means of sound absorbing material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
  • F24F13/24—Means for preventing or suppressing noise

Definitions

• the present invention is related to a silencer for the s discharge of a centrifugal blower, according to the preamble of the claims.
• Centrifugal blowers of the known type comprise a discharge having a constriction in the shape of a tongue formed in such a way that the effective discharge opening only covers o 60-70 % of the total cross section.
• This constriction provides the medium from the blower with a velocity profile having an oblique distribution across the cross section of the discharge, as can be seen from figure 1 which schematically discloses the discharge velocity along the cross section in four different s distances from the discharge. As can be seen from figure 1 in the drawing, the highest velocity exists approximately near the circumference of the blower wheel.
• Known silencers for centrifugal blowers lead the air flow from the blower into a box which normally is constructed o with a forechamber, sound absorbing plates at a distance from each other in such a way that channels are established between them, as well as a second chamber before the discharge.
• the purpose of the forechamber is to distribute the air evenly to all slots between the plates, before the air enters the slots.
• Such 5 structures necessarily are voluminous and the costs increases correspondingly for production as well as installation.
• the flow medium will experience a pressure loss in the chamber due to loss of velocity pressure.
• the flow medium also will experience further losses due to friction and 0 impacts on the different parts of the structure.
• figure 1 schematically the distribution of the velocity across the cross section of the centrifugal blower at four different distances from the discharge in a traditional blower
• figure 2 discloses schematically the silencer according to the present invention secured to a centrifugal blower, seen in a vertical section
• figure 3 discloses the blower in figure 2 in perspective
• figure 4 discloses a front view of the blower in figure 3
• figure 5 discloses a vertical section V in a slot in the silencer in figure 3
• figure 6 discloses a horizontal section VI through the silencer in figure 3.
• the medium gains the pressure drop which the medium has accumulated on its way through the silencer, as the velocity pressure is transformed to static pressure, corresponding to the friction pressure through the silencer.
• the conditions for the outlet of the silencer are optimized and additionally the velocity profile is completely equalized through the silencer. Also the silencing effect is improved.
• Figures 2-6 disclose one embodiment of the silencer according to the present invention, having vertically arranged sound dampening slots 5 for thoroughgoing flow of the medium. Depending of the local arrangement and other parameters, these slots may be arranged vertically or horizontally.
• the silencer preferably may have a shape as disclosed in figure 5 where the connecting funnel 6 ensures that the inlet of the silencer completely corresponds with the outlet 2 of the centrifugal blower. In this way negative effects from the tongue 7 of the centrifugal blower are avoided.
• the silencer has a shape according the diffusor principle where two slots 5 extend from the outlet 2 of the blower 1 to the outlet of the silencer.
• a thin partition wall 4 is arranged between the slots 5 and a surrounding isolating material 3 covers the vertical slots 5 above and below and at the sides.
• the air velocity is set to approximately 20 m/s and to establish a transition between the outlet 2 of the centrifugal blower and the dampening portion of the silencer thereby establishing a diffusor effect.
• the transition is made in such a way that a constant total cross section is maintained from the inlet of the silencer, by a s tapered portion 8, whereby an increased sound dampening effect is achieved.
• Constant cross section in the transition area is achieved by increasing the width of the transition wall 4 and thereby make the width of the slots 5 smaller along the tapered o portion 8 and at the same time increase the height of the slots 5.
• the entire partition wall 4 may as such be tapered along its length from silencer inlet to its outlet, or the partition wall may be a parallel prolongation of the tapered s portion 8.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=19898190

Family Applications (1)

Country Status (4)

Families Citing this family (3)

Family Cites Families (3)

• 1995
  • 1995-05-09 NO NO951826A patent/NO301787B1/no unknown
• 1996
  • 1996-05-08 EP EP96915242A patent/EP0839287A1/en not_active Withdrawn
  • 1996-05-08 WO PCT/NO1996/000111 patent/WO1996035879A1/en not_active Application Discontinuation
  • 1996-05-08 AU AU57062/96A patent/AU5706296A/en not_active Abandoned

Non-Patent Citations (1)

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