RU195479U1 - Axial fan impeller - Google Patents

Abstract

The invention relates to axial fans for moving air through a heat exchanger intended for use in automobile cooling and heating systems. The axial fan impeller contains a central hub, an outer ring and a plurality of vanes located between them. The blades have root and end parts and are limited by a convex edge and a concave edge. The root part of the blade is attached to the hub and the end part to the outer ring. The blades are spaced apart by unequal intermediate angles (Θi ... n), which vary in percentage terms from 4.7% to 12.8% compared to configuration with equal intermediate angles (Θ =) for the impellers with the same number of blades (see the table). The intermediate angles of the corresponding pairs of blades - the second Θ and seventh третьей, third Θ and sixth Θ, fourth Θ and fifth Θ are equal to each other (see the above table). Technical result from using Ia all essential features of the utility model is to provide a low noise level at a high efficiency.

Description

The invention relates to axial fans for moving air through a heat exchanger intended for use in automobile cooling and heating systems.

Fans of this type must meet certain requirements, including low noise, high efficiency, small size and the ability to provide satisfactory values of pressure and flow.

Known fan with blades, which have equal intermediate angles. The blades have an unchanged chord length along their entire length and are bounded at the leading and trailing edges by two curves, which in the projection onto the plane of rotation of the fan wheel are two circular arcs (see patent EP0553598B, IPC 7 F04D29 / 32; F04D29 / 38, 1993 .).

A fan wheel for a radiator fan module in a car is known. The fan impeller contains: a hub, a casing, a plurality of blades that extend from the hub outward and connected to each other through the casing, and a plurality of streamlined fins that are located between the blades on the underside of the casing (see US2018202452, IPC F01P11 / 10; F01P5 / 06; F04D29 / 16; F04D29 / 32; F04D29 / 52; F04D29 / 66 (2018.01), 2018).

Although fans made according to these patents can achieve good results in terms of efficiency and low sound pressure level, noise distribution can be annoying to a person’s ear.

Aerodynamic noise can be caused by various types of sources (monopole, dipole, quadrupole). These sources have different origins, but they can be divided into two large groups: sources that cause broadband noise (in which all frequencies are equally present), and sources that cause discrete (tonal) noise (radiation is concentrated only at certain frequencies).

The discrete components of the acoustic spectrum associated with rotation noise and interaction, as a rule, have 15–20 dB higher levels than broadband turbulent and vortex noise. Therefore, discrete noise has the most annoying effect on people. The main source of discrete noise are the blades. In fact, when the blades are separated from each other through the same angles, there is resonance with the main harmonic, the frequency of which is the product of the number of revolutions per second of the fan wheel and the number of blades. This resonance leads to a whistling noise that annoys a person’s ear.

A method is used to reduce rotation noise by installing blades with an uneven pitch. With an uneven step, a sequence of sound pressure pulses will be emitted from each of the blades at non-uniform intervals of time, which leads to a decrease and “erosion” of discrete components.

Known axial fan rotating in the plane (XY) and containing a Central hub and many blades. Each scapula has a root part and an end part. The blades are limited by the first edge and the second edge and consist of sections with aerodynamic profiles, in which the blade installation angle (β) gradually and continuously decreases from the root to the end of the blade. The blade installation angle (β) is defined as the current angle between the plane of rotation (XY) and the straight line connecting the leading edge and trailing edge of the aerodynamic profile of each blade section. The blades are separated from each other by unequal intermediate angles (Θi ... n), which can vary in percentage terms (Θ%) by values between 1.5 and 8.5% compared to the configuration with equal intermediate angles (Θ =) for fans with the same number of blades, i.e. 1.5% ≤Θ% ≤8.5%. This fan is balanced due to the fact that the projection of a convex edge onto a plane (XY) is determined by a parabolic segment and that the projection of a concave edge onto a plane (XY) is determined by a geometric curve of the second degree (see RF patent 2208712, IPC F04D 19/00 (2000.01), F04D 29/38 (2000.01), F04D 29/66 (2000.01), 2003). This decision was made as a prototype.

The disadvantage of this solution is a slight decrease in sound level, which is caused by the choice of the size of unequal intermediate angles between the blades. To balance the impeller, the displacement of the blades is made at small angles and at the same time there is an alternation of positive and negative deviations from the average value.

The technical problem solved by the utility model is the improvement of the acoustic performance of the axial fan when a high efficiency is achieved.

The technical problem posed is solved due to the fact that in the known impeller of an axial fan containing a central hub, an outer ring and a plurality of blades having root and end parts and spaced apart by unequal intermediate angles (Θi ... n) that change in percentage (Θ%) compared to the configuration with equal intermediate angles (Θ =) for impellers with the same number of blades, according to the utility model, unequal angles vary in percentage terms from 4.7% to 12.8% s P a gradual increase in the gap between the blades.

The intermediate angles of the corresponding pairs of blades - the second and seventh, third and sixth, fourth and fifth are equal to each other.

The impeller is made symmetrical, with the axis of symmetry passing along the bisector of the angle Θ ₁ .

The technical result from the use of all the essential features of a utility model is to provide a low noise level with a high efficiency.

Due to the change in unequal angles in percentage terms from 4.7% to 12.8% with a gradual increase in the gap between the blades, the effect of reducing discrete noise is achieved, which ensures a low noise level at a high efficiency.

This solution allows you to achieve the maximum possible, without loss of efficiency, changing the gap between the blades.

The diagram shows a front view of the axial fan impeller.

The impeller of the axial fan contains a central hub 1, an outer ring 2 and a plurality of blades 3 located between them. The blades 3 have a root 4 and an end 5 part and are limited by a convex edge 6 and a concave edge 7. The root part 4 of the blade is attached to the hub 1, and the end part 5 to the outer ring 2.

The blades 3 are separated from each other by unequal intermediate angles (Θi ... n), which vary in percentage terms from 4.7% to 12.8% compared to the configuration with equal intermediate angles (Θ =) for impellers with the same the number of blades (see table).

The intermediate angles of the corresponding pairs of blades - the second Θ ₂ and the seventh Θ ₇ , the third Θ ₃ and the sixth Θ ₆ , the fourth Θ ₄ and the fifth Θ ₅ are equal to each other (see the table below).

The impeller is made symmetrical, with the axis of symmetry passing along the bisector of angle Θ ₁ (see Fig. 1).

As the tests showed, the decrease in sound level, compared with the impeller with equal intermediate angles, for the impeller with a diameter of 285 mm at a speed of 3100 min ^-1 , amounted to 8 dBA (see Test report).

The impeller of the axial fan can be made on modern equipment from existing materials (various types of plastics, for example, from impact-resistant glass-filled thermally stabilized polyamides).

The claimed utility model can be used in mechanical engineering for axial fans, intended for use in cooling and heating systems of automobiles.

Table 1

Angle Impeller with unequal angles, degrees. Impeller with equal angles, degrees. Deviations, hail. Deviations,% Θ ₁ 58 51,429 6,571 12.78 Θ ₂ 55 51,429 3,571 6.94 Θ ₃ 49 51,429 -2,429 -4.72 Θ ₄ 47 51,429 -4,429 -8.61 Θ ₅ 47 51,429 -4,429 -8.61 Θ ₆ 49 51,429 -2,429 -4.72 Θ ₇ 55 51,429 3,581 6.94

Claims (3)

1. The impeller of the axial fan, containing a central hub, an outer ring and a plurality of blades having root and end parts and spaced apart by unequal intermediate angles (Θi ... n), which change in percentage terms (Θ%) compared to configuration with equal intermediate angles (Θ =) for fans with the same number of blades, characterized in that the uneven angles vary in percentage terms from 4.7% to 12.8% with a gradual increase in the gap between the blades. 2. The impeller according to claim 1, characterized in that the intermediate angles of the corresponding pairs of blades - the second and seventh, third and sixth, fourth and fifth are equal to each other. 3. The impeller according to paragraphs. 1 and 2, characterized in that it is made symmetrical, with the axis of symmetry being the bisector of angle Θ ₁ .

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