JPS63243495A - Blower device for air conditioner - Google Patents

Abstract

PURPOSE:To prevent a reverse flow of air caused by a low pressure in the peripheral part of a fan so as to eliminate the generation of turbulent noise, by additionally providing a partitioning plate, whose internal diameter has a value equal to or less than the outside diameter of an impeller, concentrically with a bell in the downstream side from a trailing edge of the impeller. CONSTITUTION:Air passes through a filter 1 and a heat exchanger 2, further the air, after it is sucked to a propeller fan 4, driven by a motor 5, along a flow path formed by a unit external frame 8, passes through a guard 6 being delivered to the outside. And a blower device, in order to separate a low pressure chamber from delivery space, provides a bell part 3, having a diameter larger than the outside diameter of an impeller, in the vicinity of the blade peripheral part of the fan 4. In the above constitution, a partitioning plate 7, whose internal diameter has a value equal to or less than the outside diameter of the impeller, is additionally provided in the downstream side of the bell part 3. In this way, the device, which prevents a reverse flow of the air to a low pressure side even when a low pressure is generated in the peripheral part of the fan 4, thus eliminates the generation of turbulent noise due to the reverse flow.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an outdoor unit of an air conditioner known as a room air conditioner, and particularly to a blower device downstream of the trailing edge of an impeller suitable for reducing noise. It is something.

[Conventional technology]

The rear edge of the conventional propeller fan for air conditioners is
．． As described in No. 58-44298, a pole mouth having a diameter slightly larger than the outer diameter of the impeller was installed near the trailing edge of the impeller and upstream from the trailing edge of the blade.

[Problem that the invention seeks to solve]

The above conventional technology relied on a method of determining the superiority or inferiority of propeller fans for air conditioners, including the bell mouth, based on their individual characteristics in terms of aerodynamics and noise, and incorporating this into a pre-designed unit structure. There was no sufficient consideration given to the noise mainly caused by the structure of the unit, and even though the fan itself had low noise, when it was incorporated into the unit, the noise level increased by 7 to 10 dB. 6. An object of the present invention is to solve the problem of high noise when incorporated into a unit, and to provide an air conditioner that is quiet rather than low noise.

[Means for solving problems]

The purpose of the above is that when the unit is installed, the speed distribution at the propeller fan inlet becomes uneven due to the size of the unit at the inlet, and the load distribution of the impeller blades changes irregularly. Focusing on the phenomenon that the discharge flow re-enters the fan inlet side from the gap between the mouths and increases the turbulent noise, we tried to prevent the discharge flow from leaking from the gap between the impeller and the bell mouth as much as possible at the trailing edge of the impeller. This can be achieved by providing a partition plate downstream of the trailing edge of one blade, the diameter of which is equal to or smaller than the outer diameter of the impeller, and which is concentric with the bell mouth to prevent backflow.

[Effect]

Propeller fans that are normally used under pressure, such as air conditioners, have a bell mouth on the trailing edge of the outer periphery of the impeller, which separates the low-pressure chamber on the suction side from the space on the discharge side, allowing heat exchange on the suction side. It exerts a blowing effect by overcoming the fluid resistance of containers etc. Further, since the impeller normally rotates and the bell mouth is stationary, a gap exists between the two in the radial direction to prevent the impeller from being damaged when foreign matter gets mixed in (for example, frost). Even if this gap is under pressure, there is no noise problem when the pressure is relatively low, but as the pressure gradually increases, the high-pressure fluid leaks from the gap and flows into the fan again, causing fan noise. It becomes higher by several dB to 10 dB.

This happens even with a single fan on the low flow rate and high pressure side, but in the case of an air conditioner (1) For example, when installing a heat exchanger on the suction side, the outer frame of the unit to form the flow path is the same as above. This can cause backflow. In other words, unlike the case where suction is drawn from an infinite space upstream of the fan, if a box-shaped unit is installed in a manner that blocks the suction flow path, the pressure will be locally low around the fan's periphery, and this will cause local backflow. This will result in higher noise levels.

〔Example〕

The technology to solve this problem and its effect are shown in Figures 1 and 2 below.
This will be explained according to the embodiment shown in the figure.

Air filter 1. It passes through the heat exchanger 2, is sucked into the propeller fan 4 driven by a predetermined motor 5 along a flow path determined by the unit outer frame 8, is pressurized, and passes through a guard 6 provided to prevent danger. and is discharged to the outside.

A bell mouth 3 is provided near the outer periphery of the fan blade, the diameter of which is larger than the outer periphery of the impeller and at the trailing edge of the blade, in order to separate the low pressure chamber and the discharge space.Usually, this bell mouth and the outer periphery of the blade Since the fluid does not receive any energy from the vanes in the gap between the blade and the blade, when the pressure in the low pressure chamber decreases, air will flow backwards through this gap. In Figure 1, the downstream side of this bell mouth has an inner diameter (φDr) equal to or smaller than the impeller outer diameter (this value varies depending on the characteristics of the blower, but it is generally an area around the outer circumference of the impeller where less energy is transferred). A partition plate 7 (having a diameter of
It has a structure that eliminates the causes of high noise.

The inner diameter (φDz) of the partition plate 7 is the outer diameter (φDz) of the impeller.
It is important in relation to In other words, since there must be no backflow from the gap, it must be smaller than the outer diameter of the impeller, and since the blades have a finite length at the outer periphery of the impeller, there is a region with low energy due to the influence of the blade tips. In order to prevent backflow from this point, the value must be smaller than the outer circumferential diameter of the blade. Furthermore, the diameter must not be so small as to block the main stream in a high energy state at the impeller outlet. φD8
indicates the bell mouth inner diameter.

According to this embodiment, since there is an outer frame of the unit, backflow can be prevented even when the pressure at the outer circumference of the fan is relatively low, and generation of turbulent noise due to this backflow can be prevented. It is possible to provide a blower structure for an air conditioner.

[Effects of the Invention] According to the present invention, it is possible to prevent backflow to the low-pressure side due to a localized low-pressure state on the outer periphery of the fan caused by the unit outer frame device, and to prevent the generation of turbulent noise caused by this backflow. It is possible to prevent this.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a blower device showing one embodiment of the present invention, and FIG. 2 is a front view taken in the direction of arrow A in FIG. 1... Filter, 2... Heat exchanger, 3... Bell mouth. 4...propeller fan, 5...motor, 6...guard, agent and patent attorney Katsuma Ogawa□...,,・'th
21! ]

Claims (1)

[Scope of Claims] 1. In an air conditioner using a propeller fan with a bell mouth, the impeller is located downstream of the trailing edge of the impeller and concentrically with the bell mouth, and has the same outer diameter as the impeller, or has an outer diameter of the impeller. A blower device for an air conditioner characterized by having a smaller partition plate. 2. A blower device for an air conditioner according to claim 1, in which the partition plate is integrally formed with the bell mouth. 3. The air conditioner blower device according to claim 1, wherein the partition plate is integrally molded from the unit outer frame member.