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EP-4234946-B1 - MULTIBLADE CENTRIFUGAL FAN

EP4234946B1EP 4234946 B1EP4234946 B1EP 4234946B1EP-4234946-B1

Inventors

  • HAYASHI, HIROYASU
  • TERAMOTO, TAKUYA
  • FUJIKI, Katsuhiro
  • SHINGU, Wahei

Dates

Publication Date
20260506
Application Date
20201023

Claims (4)

  1. A multi-blade centrifugal air-sending device (100) comprising: an impeller (10) including a back plate (11) having a disk shape, a plurality of blades (12) arranged at a peripheral portion of the back plate (11) in a circumferential direction, and a rim (13) having an annular shape and disposed to face the back plate (11) in an axial direction of a rotational axis (RS) of the impeller (10), the rim (13) fixing the plurality of blades (12); and a scroll casing (20) having a spiral shape and housing the impeller (10), the scroll casing (20) being configured such that air is introduced from a side of the rim (13) and blown out to an outer peripheral side, wherein each of the blades (12) includes a sirocco blade portion (30) constituted by a forward blade, and a turbo blade portion (40) constituted by a rearward blade and connected to an inner peripheral side of the sirocco blade portion (30), wherein, when viewed in the axial direction of a rotational axis (RS) of the impeller (10), a portion of each of the blades (12) covered by the rim (13) is constituted by the sirocco blade portion (30) and a portion of the turbo blade portion (40), and wherein a chord length of the sirocco blade portion (30) is larger than a chord length (L2) of the portion of the turbo blade portion (40). wherein the impeller (10) is constituted by a metal, and wherein each of the blades (12) has a wall thickness (W) constant from one end connected to the back plate (11) to of the other end connected to the rim (13), the one end and the other end being the ends of both sides of the each of the blades (12) in the axial direction of a rotational axis (RS), and each of the blades (12) from the one end to the other end extends toward an inner side further than an inner peripheral end (13a) of the rim (13), the inner side being the side where the air is introduced in the radial direction of the rotational axis (RS).
  2. The multi-blade centrifugal air-sending device (100) of claim 1, wherein an inner peripheral edge (12f) of each of the blades (12) is inclined from the side of the rim (13) toward the side of the back plate (11) such that a distance between the inner peripheral end (13a) of the rim (13) and an inner peripheral end (12fd) of the inner peripheral edge (12f) of each of the blades (12) on the side of the back plate (11) is larger than a distance between the inner peripheral end (13a) of the rim (13) and an inner peripheral end (12fu) of the inner peripheral edge (12f) of each of the blades (12) on the side of the rim (13).
  3. The multi-blade centrifugal air-sending device (100) of claim 1, wherein a percentage of the chord length (L2) of the portion of the turbo blade portion (40) with respect to a chord length (L1) of the portion of each of the blades (12) is larger than 0% and less than or equal to 30%.
  4. The multi-blade centrifugal air-sending device (100) of any one of claims 1 to 3, wherein the scroll casing (20) is a casing of a double suction and includes two facing side walls (23) in each of which an air inlet (23b) is provided, a peripheral wall (24), and a bell mouth (26) forming the air inlet (23b) and having an opening diameter gradually decreasing toward an inside, and wherein the inner peripheral end (13d) of the rim (13) is positioned on an inner peripheral side with respect to an outer peripheral end (26a) of a tip of the bell mouth (26).

Description

Technical Field The present disclosure relates to a multi-blade centrifugal air-sending device including an impeller. Background Art A multi-blade centrifugal air-sending device includes an impeller and a scroll casing having a spiral shape and housing the impeller. The impeller is constituted by a back plate, a rim having an annular shape and facing the back plate, and a plurality of blades provided between the back plate and the rim. The impeller sucks air from the side of the rim by rotating and causes the air to flow out to an air passage in the inside of the scroll casing through a gap between blades. The airflow is pressurized in the air passage in the inside of the scroll casing and blown out through a discharge port. As a means for increasing the air volume in the multi-blade centrifugal air-sending device, there is a method of increasing the number of the blades. When the number of the blades is increased to increase the air volume, however, noise is increased due to the increase in the number of the blades. Thus, there is a device (refer to, for example, Patent Literature 1) in which a forward blade is provided on the outer peripheral side of a blade and a rearward blade is provided on the inner peripheral side of the blade to thereby increase the suction air volume with the rearward blade without increasing the number of blades. In the multi-blade centrifugal air-sending device disclosed in Patent Literature 1, the rearward blade provided on the inner peripheral side of the blade is configured to be disposed and exposed on the inner side of the inner peripheral end of a rim, and air is taken in by the exposed rearward blade. An impeller in the multi-blade centrifugal air-sending device in Patent Literature 1 is formed with a resin material by injection molding. Patent Literature 2 discloses a centrifugal radiator fan's impeller. A fan assembly having an impeller with a hub ring and one or more hub strips to support a plurality of blades, each having a preferred ratio of a chord distance to a camber distance between 1,5 and 10, is known from Patent Literature 3. Patent Literature 4 deals with a centrifugal multiple blade type motor driven blower. Patent Literature 5 discloses a forward curved blower wheel. Citation List Patent Literature Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2012-36885Patent Literature 2: CN 205 298 053 UPatent Literature 3: US 2012/201680 A1Patent Literature 4: JP H09 256994 APatent Literature 5: US 2017/234323 A1 Summary of Invention Technical Problem When an impeller is formed with a resin material by injection molding as in Patent Literature 1, however, the wall thickness of a blade is larger on the side of a back plate than on the side of a rim generally due to the moldability of the impeller, and a gap formed between blades is narrower on the side of the back plate than on the side of the rim in the impeller. Therefore, although the rearward blade is exposed from the inner peripheral end of the rim in the multi-blade centrifugal air-sending device in Patent Literature 1, it may be impossible on the side of the back plate to sufficiently take air that has reached the vicinity of the rearward blade into the gap between the blades and may be impossible on the side of the back plate in the impeller to obtain an effect of increasing the suction air volume. The present disclosure has been made to solve the aforementioned problem, and an object of the present disclosure is to provide a multi-blade centrifugal air-sending device capable of increasing the suction air volume on the side of a back plate in an impeller, compared with a multi-blade centrifugal air-sending device constituted by a resin material as in the related art. Solution to Problem The invention is defined by claim 1. In particular, a multi-blade centrifugal air-sending device according to the present disclosure includes an impeller including a back plate having a disk shape, a plurality of blades arranged at a peripheral portion of the back plate in a circumferential direction, and a rim having an annular shape and disposed to face the back plate, the rim fixing the plurality of blades; and a scroll casing having a spiral shape and housing the impeller, the scroll casing being configured such that air is introduced from the side of the rim and blown out to the outer peripheral side. The impeller is constituted by a metal. Each of the blades has a wall thickness constant from the side of the back plate to the side of the rim and extends toward the inner side further than an inner peripheral end of the rim. Advantageous Effects of Invention According to the present disclosure, since the impeller is constituted by a metal, and the wall thickness of each of the blades is constant from the side of the rim to the side of the back plate, a gap between blades similar to that on the side of the rim in the impeller can be ensured also on the side of the back plate in the impeller at a por