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
  • F04D25/00—Pumping installations or systems
  • F04D25/02—Units comprising pumps and their driving means
  • F04D25/08—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation
  • F04D25/082—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation the unit having provision for cooling the motor
• • 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
  • F04D29/58—Cooling; Heating; Diminishing heat transfer
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
  • F04D17/08—Centrifugal pumps
  • F04D17/16—Centrifugal pumps for displacing without appreciable compression
• • 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
  • F04D29/58—Cooling; Heating; Diminishing heat transfer
  • F04D29/5806—Cooling the drive system

Definitions

• This invention relates to a centrifugal fan and in particular a centrifugal fan comprising a system of cooling the motor of the fan.
• These fans are conveniently provided with systems for cooling the relative drive motors based on a forced circulation of cooling air.
• Figure 1 illustrates a prior art centrifugal fan, in a schematic view partly in cross-section.
• This type of fan comprises a scroll-shaped outer casing 100, formed by a central portion 101 and an outlet channel 102 in communication with the central portion 101.
• the casing 100 has an inlet opening 103 formed in the central portion 101 and an outlet opening 104 formed at the end of the channel 102.
• a motor 105 is mounted inside the scroll for driving a centrifugal impeller 106, rotating around its axis R, which sucks air at the inlet opening 103 and introduces the blown air into the channel 102 of the scroll 2.
• the impeller 106 After being placed in rotation, the impeller 106 generates a pressure difference between the inlet opening 103 and the outlet opening, 104 so as to generate a flow F of air along the channel 102. Generically, it is indicated that there is a high pressure at the outlet, or outside, of the fan whilst there is a negative pressure (compared with the outlet) at the inlet, or inside.
• the cooling system of the motor 105 comprises a recirculation duct 107 having inlet in communication with the channel 102 and outlet in communication with the central portion 101.
• the duct 107 collects pressurised air at the outlet of the casing 100 so as to form a flow RF of cooling air which is pushed, from the over-pressure coming from the impeller 106, to the central portion 101 at the rear part of the motor 105.
• the flow RF of cooling air passes through the aeration holes 105a of the motor 105 removing the heat directly from the windings of the motor 105 and again reaching the inside of the impeller 106 and from there reintroduced into the channel 102.
• the main technical purpose of this invention is to provide a centrifugal fan which is free of the above-mentioned drawbacks .
• One aim of this invention is to provide a centrifugal fan equipped with a highly efficient cooling system.
• Another aim of this invention is to provide a fan equipped with a cooling system which is able to remove large quantities of heat from the motor driving the impeller, also, for example, in the case of adoption of a closed motor in which the cooling components may not be directly exposed to a forced flow of cooling air.
• Figure 1 illustrates a schematic view of a prior art centrifugal fan .
• Figure 2 illustrates a cross-sectional schematic view of a first embodiment of a centrifugal fan according to this invention
• Figure 3 illustrates a top plan view of a second embodiment of a centrifugal fan according to this invention
• Figure 4 illustrates a schematic cross-section according to the line IV - IV of the fan of Figure 3;
• Figure 5 illustrates a conveniently scaled-up portion of the fan of Figure 4.
• Figure 6 illustrates a top plan view of the fan of Figure 3, with some parts cut away to better illustrate others;
• Figure 7 illustrates a first ⁇ perspective view of a first embodiment of a impeller of a centrifugal fan according to this invention
• Figure 8 illustrates a second perspective view of the impeller of Figure 7
• Figure 9 illustrates a partly schematic cross-section of a
• Figure 10 illustrates schematic perspective view ' of a detail of the centrifugal impeller of the fan of Figure 9.
• the numeral 1 denotes a centrifugal fan according to this invention.
• the fan 1 which has an axis of rotation R, comprises a casing, or volute or scroll 2, an electric motor 3, preferably of the closed or “sealed” type, having a corresponding shaft 3a, located inside the casing 2 and supported by it and a centrifugal impeller 4, illustrated in particular in Figures 7 and 8, driven by the motor 3.
• the impeller 4, rotatable around the axis R comprises a plurality of centrifugal blades 5, having main extension according to the axis R, and a first and a second support ring 6, 7 between which the blades 5 extend.
• the impeller 4 has a first inlet 8, formed by the opening delimited by the support ring 7, coaxial to the axis R, and a tangential outlet 9 defined, in practice, by the spaces between the blades 5.
• the impeller 4 comprises a hub 10, connected to the first support ring 6, for coupling with the motor 3.
• the hub 10 has a sleeve 11, for coupling with the shaft 3a, from which a plurality of arms 12 extend for connecting with the ring 6.
• the hub 10 also comprises a central portion 13 which extends from the sleeve 11 between the arms 12 and delimits, with the arms 12 and the support ring 6, a plurality of openings 14.
• the motor 3 is partially inserted inside the hub 10 whilst in alternative embodiments not illustrated the motor 3 is outside the hub 10.
• the aforesaid casing 2 has an axial inlet opening 15, that is, coaxial with the axis of rotation R (and therefore coaxial with the inlet 8 of the impeller 4), and a tangential outlet opening 16, located in a known manner with respect to the impeller 4, for circulating the air moved by the impeller 4.
• the casing 2 comprises a main body which has a central portion 17 in which is formed the inlet opening 15 and an outlet channel 18, which extends tangentially from the central portion 17 and is in fluid communication with it, and at the free end of which is located the outlet opening 16.
• the fan 1 comprises a cover 19 for closing the casing 2 to which, preferably, the motor 3 is anchored.
• the cover 19 is located, relative to the motor 3, from the opposite part of the impeller 4 and it is coupled to the central portion 17 of the main body.
• the cover 19 forms a housing 20 for the motor 3 in which the motor 3 is partially located.
• the cover 19 has an inner cylindrical side wall 21 and an inner rear wall 22 joined with the side wall 21 delimiting the housing 20 and the motor 3 is located in a coaxial fashion inside the housing 20.
• the upper portion 3b of the motor 3 is the portion of the motor 3 which is housed in the housing 20 and the lower portion 3c of the motor 3 is the portion partly inserted in the hub 10.
• An air circulation zone 32 is defined between the motor 3, specifically between its upper portion 3b, and the cover 19.
• the fan 1 comprises a cooling system for removing heat from the motor 3 by means of a flow RF of cooling air directed from the inside of the casing 2 towards the outside of it.
• the flow RF of cooling air consists of a tangential component and an axial component, directed according to the axis of rotation R.
• the tangential component and the axial component are added vectorially generating, as the resultant, a helical vortex RF around the motor 3.
• the cooling system of the motor 3 comprises, for generating the aforesaid axial component, the impeller 4 and a duct 30 having inlet 26 in the outlet channel 18 and outlet 27 in the central portion 17, substantially at the motor 3.
• an over-pressure is created at the outlet 9 of the impeller 4, in particular also at the inlet 26 of the duct 30.
• This over-pressure pushes air along the duct 30 from the inlet 26 towards the outlet 27; the flow of air exiting from the duct 30 forms the aforesaid axial component.
• the cooling system For generating, in use, the aforesaid tangential component of the cooling flow RF, the cooling system comprises a collar 28 integral with the impeller 4 and extending axially from the impeller 4 towards the motor 3, outside of it, and a plurality of radial blades 29, supported by the collar 28 and facing the motor 3.
• the collar 28 is made in a single body with the impeller 4 and extends from the support ring 6 on the opposite side with respect to the blades 5.
• the radial blades 29 extend between the support ring 6 and the outer collar 28 and they extend from the latter towards the motor 3.
• the outer collar 28 together with the blades 29 surround the motor 3 and in particular the upper portion 3b of the motor.
• the aforesaid housing 20 is designed to accommodate, in addition to the motor 3, also the collar 28 and therefore the blades 29.
• the effect of the rotation of the blades 29 is, in other words, that of dragging the air contained in the hollow space between the blades 29 and the motor 3, generating the tangential component of the cooling flow RF.
• the aforesaid axial component is advantageously directed from the upper portion 3b of the motor towards the lower portion 3c of the motor, inside the casing 2, in such a way that the cooling flow RF, resultant from the combination between the tangential component and the axial component moves, through the openings 14 of the hub 10, to the inside of the impeller 4, from where it is expelled outside the casing 2 through the outlet opening 16.
• the cooling system comprises a hollow space 31, or annular channel 31, formed between the cylindrical outer wall of the collar 28 and the cylindrical side wall 21 of the housing 20.
• the annular channel 31 places the channel 18 in fluid communication with the central portion 17 of the casing 2 at the upper part 3b of the motor 3.
• the cover 19 is shaped in such a way that the annular hollow space 31 is in fluid communication with the channel 18.
• reference numeral 31a indicates the inlet of the annular channel 31 and reference numeral 31b indicates the outlet of the channel 31.
• the cooling system comprises, similarly to the first embodiment, the collar 28 integral with the impeller 4 and extending axially from the impeller 4 towards the motor 3, outside of it, and the radial blades 29 supported by the collar 28 and facing the motor 3.
• the collar 28 is made in a single body with the impeller 4 and extends from the support ring 6 on the opposite side with respect to the blades 5.
• the radial blades 29 extend between the support ring 6 and the outer collar 28 and they extend from the latter towards the motor 3.
• the outer collar 28 together with the blades 29 surround the motor 3 and in particular the upper portion 3b of the motor.
• the aforesaid housing 20 is designed to accommodate, in addition to the motor 3, also the collar 28 and therefore the blades 29.
• the effect of the rotation of the blades 29 is, in other words, that of dragging the air contained in the .hollow space between the blades
• the impeller 4 pushes air at high speed along the canal 18.
• the high speed air generates a Venturi effect which generates, in turn, a negative pressure at the outlet 31b of the channel 31.
• the negative pressure causes a suction effect along the hollow space 31 of the flow of cooling air.
• a suction flow is generated in the annular channel 31 directed from the inlet 31a to the outlet 31b.
• the suction along the hollow space 31 generates, inside the central portion 17 of the ' casing 2, the so-called axial component substantially directed according to the axis of rotation R of the motor 3 inside the casing 2.
• the axial component is advantageously directed from the lower portion 3c of the motor towards the upper portion 3b of the motor, inside the casing 2, in such a way that the helical cooling flow RF, resultant from the combination between the tangential component and the axial component moves, through the openings 14 of the hub 10, through the impeller 4, to the zone 32 from where it is expelled outside the casing 2 through the hollow space 31 and the channel 18.
• the axial component combines with the tangential flow due to the blades 29 generating the aforesaid helical vortex RF which is carried from inside the casing 2 to the outside of the casing 2 through the hollow space 31 and the channel 18.
• the annular channel 31 has the outlet 31b delimited between the cover 19 and the impeller 4, having dimension "h” of the same order of magnitude as the dimension "hi” of the channel 31 between the collar 28 and the cylindrical side wall 21 delimiting the housing 20.
• the cover 19 is shaped in such a way as to delimit the outlet 31b with the first support ring 6 and/or with the blades 5.
• the outlet 31b of the annular channel 31 is advantageously formed by the support ring 6 and specifically by an annular rim 60 of it which faces a corresponding annular portion 19a of the cover 19.
• the annular hollow space 31 is in communication with the air circulation zone 32, where the inlet 31a is formed.
• the flow drawn along the hollow space 31 combines in the zone 32 with the tangential flow due to the blades 29, generating the aforesaid vortex RF around the motor 3 which is sucked into the channel 18.
• the air circulation zone 32 is defined between the rear wall 22 of the housing 20 and the rear, surface 33 of the motor 3 to which it faces .
• the inside of the housing 20 is provided with the space for the circulation of the air both between the side wall and between the base wall of the motor 3 and the cover 19.
• FIG. 9 A third embodiment of a fan according to this invention is illustrated in Figure 9.
• the suction of the cooling flow across the hollow space 31 is assisted by a series of centrifugal blades 40 positioned on the outside of the collar 28 for forcing the air from the hollow space 31 towards the outlet opening of the channel 18.
• the centrifugal blades 40 extend from the opposite side with respect to the motor 3 and form a second auxiliary centrifugal fan 41 which further pushes the cooling flow, resultant from the combination of the tangential component with the axial component, from the hollow space 31 towards the outside of the casing 2.
• each blade 40 is advantageously made in a single body with the collar 28 and extend outside the collar, . as also shown in Figure 10.
• each blade 40 is formed as an extension of a corresponding blade 5 of the impeller 4, as shown in Figure 10.
• the cooling system, and the blades 29 in particular are designed in such a way that the tangential component is of an order of magnitude greater than the axial component for effectively removing heat from the motor 3.
• the duct 30 external to the casing 2 in the first embodiment and the hollow space or annular channel 31 in the second and in the third embodiment define a ventilation channel forming part of the cooling system of the fan 1 thanks to which the cooling flow RF defined as a helical vortex removes heat from the motor 3.
• the motor 3 is therefore touched by high speed air on the external skin which is particularly effective in the removal of heat.
• the effect of the rotation of the blades 29 is, in other words, that of dragging the air contained in the hollow space between the blades 29 and the motor 3, generating the aforesaid tangential component.
• the motor is enveloped by a helical vortex which is very effective for forced cooling without using an axial component that is detrimental for the efficiency and the noise level of the fan.
• the axial component is necessary for transporting the quantity of heat collected by the aforesaid vortex RF outside the "motor zone".
• the centrifugal fan provided with the cooling system as described allows the adoption of closed or sealed motors, which work well in harsh ambient conditions, also with drive electronics integrated inside.
• the cooling system as described allows the lifetime of the fa to be extended by up to more than 30,000 working hours compared with prior art fans.
• the proposed solutions allow maximisation of the cooling of the motor driving the impeller, minimisation of the sources of fluid dynamic noise and, at the same time, minimisation of the costs for equal performance levels by avoiding adoption of the connecting duct between fan outlet and housing of the motor.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Publications (1)

Family

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Family Applications (1)

Country Status (10)

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Citations (4)

Family Cites Families (17)

• 2011
  • 2011-09-23 IT IT000543A patent/ITBO20110543A1/it unknown
• 2012
  • 2012-09-21 RU RU2014110537A patent/RU2607116C2/ru active
  • 2012-09-21 ES ES12780800.4T patent/ES2540253T3/es active Active
  • 2012-09-21 JP JP2014531328A patent/JP6122012B2/ja active Active
  • 2012-09-21 BR BR112014006909A patent/BR112014006909A2/pt not_active Application Discontinuation
  • 2012-09-21 WO PCT/IB2012/001865 patent/WO2013041954A1/en active Application Filing
  • 2012-09-21 EP EP12780800.4A patent/EP2758671B1/en active Active
  • 2012-09-21 US US14/346,251 patent/US20140219835A1/en not_active Abandoned
  • 2012-09-21 KR KR1020147010966A patent/KR101947662B1/ko active IP Right Grant
  • 2012-09-21 CN CN201280046519.2A patent/CN103890407B/zh active Active

Patent Citations (4)

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