DESC:INJECTION MOLDED LOW NOISE FAN ASSEMBLY

Field of the invention:

The present invention generally relates to an automobile fan and more particularly, to an injection molded low noise fan assembly.

Background of the invention:

An engine cooling system of an automobile mainly consists of two components, namely a radiator assembly and a shroud assembly. The shroud assembly consists of two main components a fan and a motor. The fan is used to provide an air flow for the radiator whereas the radiator is used to cool the engine by circulating the coolant there through.

The fan delivers the air over the radiator by rotating at specified revolutions per minute (RPM), during these rotations air flow is generated and this air flow generation contributes to noise which will create discomfort to user of the automobile. The fan is rotated with the help of the electric motor mounted on the shroud assembly and the shroud assembly may be fitted on the radiator and further the radiator assembly is mounted on an automobile chassis.

The selection of the fan is based on air flow requirement, input power available and packaging dimension. The engine cooling system may use single fan as well as double fan. The fans available in the market meet the air flow with given geometry but come with a drawback of generating higher noise. Higher air flow requirement in passenger car leads to higher RPM that causes higher noise (e.g-3500 RPM) whereas fan with a smaller diameter has to rotate with higher RPM to meet air flow that again causes higher noise. Existing automobile fan generates noise in the range of 72 to 74 dB and this generated noise creates discomfort to the automobile users.

Efforts are being made in the prior art to reduce noise of the fan. Reference may be made to United States patent no. US5577888 that discloses airflow generators used to produce airflow across an automotive heat exchanger. In particular, the invention relates to an axial fan having an improved blade configuration which when combined with the fan motor support and an upstream or downstream heat exchanger improves fan efficiency and reduces noise. A high efficiency fan and stator arrangement for generating airflow through a heat exchanger is disclosed herein. The fan is rotated about its rotational axis by an electric motor, and includes eight blades extending radially from a hub to a circular band. A fan support including a shroud assembly adapted to provide a substantially closed airflow channel between the fan and the heat exchanger, further embodiments comprises an electric motor which includes a bearing assembly and shaft, wherein the shaft is attached to the fan and the bearing assembly is attached to the central support. However, this invention utilizes 8 numbers of blades and L-type feature at fan ring. Further, in the shroud design angle between two ribs is same and fan blade geometry is less curved that does not effectively reduce the noise level.

Hence, there exists a need of a technical modification in the prior art that is by making a fan assembly that generates very less noise and provide a comfortable environment for the automobile users than already existing mechanism.

Objects of the invention:

An object of the present invention is to provide a comfort to the users by developing a low noise fan assembly.

Another object of the present invention is to provide a low noise fan assembly that requires less amount of electricity/ power for operation.

Yet another object of the present invention is to provide a low noise fan assembly having a wide range of applications.
Summary of the invention:

Accordingly, the present invention provides an injection molded low noise fan assembly (hereinafter, “the fan assembly”). The fan assembly comprises a plurality of blade, a hub and a ring. The fan assembly has diameter of 370 mm. The dimension of the hub diameter is 140 mm.

The plurality of blades is attached at a predefined interval to the hub in a circular fashion. Specifically, the fan assembly includes seven numbers of blades. The predefined interval between two adjacent blades is 8.0 mm that helps to reduce noise value to 59.9 dB. Each blade has a first radius at a first portion thereof, a second radius at a second portion thereof and a third radius at a third portion thereof. Specifically, each blade has the first radius of 20 mm at the first portion thereof, the second radius of 67 mm at the second portion thereof and the third radius of 80 mm at the third portion thereof. The first radius, the second radius and the third radius provide different width at the first portion, the second portion and the third portion of each blade. The ring is attached to another end of the plurality of blades. The ring includes a leap profile configured on an outer circumference thereof. Specifically, the leap profile is “U” type leap profile that gives stability to the plurality of blades in running condition.

In accordance with the present invention, the predefined interval between two adjacent blades is less that increases a blade area that in turn increases an air flow and the increased air flow reduces revolutions per minute of the blades thereby facilitating reduction of noise value to 59.9 dB.

Brief description of the drawings:

The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein
Figure 1a shows connection details of a low noise fan assembly and an electric motor, in accordance with the present invention;

Figure 1b shows connection details of a shroud assembly and the electric motor, in accordance with the present invention;

Figure 1c shows connection details of a radiator assembly and the electric motor, in accordance with the present invention;

Figure 2 shows the low noise fan assembly, in accordance with the present invention;

Figure 3 shows a predefined interval details between two adjacent blades of the low noise fan assembly, in accordance with the present invention;

Figure 4a shows a front view of the low noise fan assembly, in accordance with the present invention;

Figure 4b is a sectional view along B-B of figure 4a showing a hub and a ring of the low noise fan assembly, in accordance with the present invention;

Figure 4c shows a leap profile of the ring of the low noise fan assembly, in accordance with the present invention;

Figure 5 shows radius details of the blade of the low noise fan assembly, in accordance with the present invention;

Figure 6a shows different thickness of the blade along section C-C, in accordance with the present invention;

Figure 6b shows a suction side and a pressure side of the blade of the low noise fan assembly, in accordance with the present invention;

Figure 7a is a back view of the low noise fan assembly showing diameter Ø370 mm, in accordance with the present invention;

Figure 7b shows dimension of the hub diameter, in accordance with the present invention;

Figure 8 shows a schematic diagram of a noise simulation experiment, in accordance with the present invention; and

Figure 9 shows a graphical representation of frequency vs. sound pressure level, in accordance with the present invention.

Detailed description of the invention:

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.

The present invention provides an injection molded low noise fan assembly. The fan assembly is operated electrically in an automobile and contributes to cooling of an engine. The fan assembly of the present invention has a design that generates very low noise as compared with the existing assembly.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

Referring to figures 1a to 7b, a low noise fan assembly (50) (hereinafter referred as ‘the fan assembly (50)’) in accordance with the present invention is shown.

The fan assembly (50) is rotated using an electric motor (60). The electric motor (60) is fitted on a shroud assembly (70). The shroud assembly (70) is fitted on a radiator assembly (80) and further the radiator assembly (80) is fitted on an automobile chassis (not shown). The shroud assembly (70) is designed in such a way that an angle between two ribs (not shown) is different. The electric motor (60) sucks air from the radiator assembly (80) and exchange the heat from a liquid inside the radiator assembly (80).

As shown in figure 2, the fan assembly (50) comprises a plurality of blades (10), a hub (20) and a ring (30). The plurality of blades (10) is attached to the hub (20) on one end thereof. In an embodiment, the fan assembly (100) includes seven number of blades (10) attached at a predefined intervals to the hub (20) in a circular fashion. Specifically as shown in figure 3, the predefined interval between two adjacent blades (10) is 8.0 mm that helps to reduce noise value to 59.9 dB. The fan assembly (50) gives the noise value of 59.9 dB which is less than the prior art assemblies. Specifically, the predefined interval/ gap between two adjacent blades (10) is less that increases the blade area that in turn increases an air flow and the increased air flow reduces revolutions per minute (RPM) of the plurality of blades (10) thereby facilitating reduction of noise value to 59.9 dB. Each blade (10) has a curved geometry. The plurality of blades (10) is attached to the ring (30) on another end thereof as shown in figures 4a-4b. The ring (30) has a leap profile (25) configured on an outer circumference thereof as shown in figure 4c. In an embodiment, the leap profile (25) is “U” type leap profile that gives stability to the plurality of blades (10) in running condition. Further, with the leap profile (25) reverse flow is reduced to curb an eddy as a source of noise that facilitates the fan assembly (50) to increase the air flow and reduce noise.

As shown in figure 5, each blade (10) has at least three different radii at three different portions thereof that provide different width at different location of each blade (10). The blade width is changed to achieve air flow as higher width increases air flow. In an embodiment, each blade (10) has a first radius of 20 mm at a first portion (2a) thereof, a second radius of 67 mm at a second portion (2b) thereof and a third radius of 80 mm at a third portion (2c) thereof. Specifically, the plurality of blades (10) is formed by a coordinate system by an airfoil process design such that each blade (10) has different thickness as shown by section C-C in figure 6a. Following Table provides X, Y and Z coordinate points of a pressure surface and a suction surface of the plurality of blades (10).

Table 1: Fan blade coordinate points

In the context of the present invention, a suction side of the plurality of blades (10) means where the plurality of blades (10) sucks air whereas a pressure side deliverers air. The suction side and the pressure side of the blade (10) are depicted in figure 6b.

In an embodiment, the diameter of the fan assembly (50) is 370 mm (refer figure 7a) and dimension of the hub diameter is 140 mm. However, it is understood here that the diameter of the fan assembly (50) and dimension of the hub diameter may vary in other alternative embodiments of the present invention. Specifically, the optimized 140 mm hub diameter as shown in figure 7b helps to increase the blade area that in turn increases air flow and the increased air flow reduces RPM. In the context of the present invention, seven blades (10) produce less air cutting noise because seven blades cut air seven times with fan blade geometry and the leap profile (25) of the ring (30) plays important role in noise reduction/generation.

In accordance with the present invention, there is a log-linear relationship between the rotational speed of the plurality of blades (10) and the noise level (expressed in decibels). As RPM of the fan increases, the fan noise increases. So it is best to have a smooth transition from the blade (10) to section. The preferred choice is for spirally curved struts that are distributed asymmetrically round the circumference of a housing that lead to less noise creation. If fewer vortexes occur, then the acoustic behaviour of the fan assembly (50) is improved. The audible sound produced by an odd number of blades and sections is easier on the human ear than that produced by an even number.

The invention is further illustrated hereinafter by means of examples.
Examples:

Example 1: Noise simulation

Figure 8 shows a schematic diagram of a noise simulation experiment, in accordance with the present invention. In this experiment, the fan assembly (50) was enclosed in a circular domain. Thereafter, prism layers were generated on the plurality of blades (10) and rest of the region was meshed with a fine tetrahedral mesh. This rotating fluid region was enclosed in an outer domain which was meshed with hexahedral cells. The simulation and experimental results are given Table 2:

Table 2: Noise simulation value
Fan identification Fan type Speed(RPM) Computational Noise dB(A)
370 Diameter Fan simulation Single fan 2400 64.7

Example 2: Rapid proto sample noise value

The fan assembly (50) was manufactured by rapid prototype method (3D printing). Following Table 3 shows speed and computational noise value of the fan assembly (50) manufactured by rapid prototype method.

Table 3:
Fan identification Fan type Speed (RPM) Computational Noise dB(A)
Rapid prototype part Single fan 2400 61.2

Example 3:

Tooled up 7 blade fan noise testing was done at ARAI with microphone position with 1.6 meter height and 1 meter distance. The raw materials used were polyamide 6 (PA6) and 30% glass reinforced (GF30). The results of speed and computational noise value of the fan assembly (50) having 370 mm diameter is given in Table 4:

Table 4:
Fan identification Fan type Speed (RPM) Computational Noise dB(A)
Tooled up part Single fan 2400 59.9
Advantages of the invention:

1. In the fan assembly (50), the predefined interval between two adjacent blades (10) is less that increases the blade area that in turn increases the air flow and the increased air flow reduces RPM thereby facilitating reduction in noise value.
2. The assembly (100) requires very less amount of electricity.
3. The assembly (100) provides comfortable environment for the automobile users.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the scope of the claims of the present invention.
,CLAIMS:We claim:

1. An injection molded low noise fan assembly (50), the fan assembly (50) comprising:
a plurality of blades (10) attached at a predefined interval to a hub (20) in a circular fashion, each blade (10) having a first radius at a first portion (2a) thereof, a second radius at a second portion (2b) thereof and a third radius at a third portion (2c) thereof, the first radius, the second radius and the third radius provide different width at the first portion (2a), the second portion (2b) and the third portion (2c) of each blade (10); and
a ring (30) attached to another end of the plurality of blades (10), the ring (30) having a leap profile (25) configured on an outer circumference thereof,
wherein, the predefined interval between two adjacent blades (10) is less that increases a blade area that in turn increases an air flow and the increased air flow reduces revolutions per minute of the blades (10) thereby facilitating reduction of noise value to 59.9 dB.

2. The fan assembly (50) as claimed in claim 1 has diameter of 370 mm and includes seven numbers of blades (10).

3. The fan assembly (50) as claimed in claim 1, wherein dimension of the hub diameter is 140 mm.

4. The fan assembly (50) as claimed in claim 1, wherein the predefined interval between two adjacent blades (10) is 8.0 mm that helps to reduce noise value to 59.9 dB.

5. The fan assembly (50) as claimed in claim 1, wherein each blade (10) has the first radius of 20 mm at the first portion (2a) thereof, the second radius of 67 mm at the second portion (2b) thereof and the third radius of 80 mm at the third portion (2c) thereof.

6. The fan assembly (50) as claimed in claim 1, wherein the leap profile (25) is “U” type leap profile that gives stability to the plurality of blades (10) in running condition.

Dated this 15th day of April 2020
Prafulla Wange
(Agent for Applicant)
IN/PA-2058