FAN ASSEMBLY

Abstract

A fan assembly is mainly provided with a center hub and a plurality of fan blades. The center hub has a center rotational axis. The fan blades extend from the center hub. Each of the fan blades has a leading surface and a trailing surface. The trailing surface of at least one of the fan blades includes an intake opening disposed at a first radial distance from the center rotational axis and a jet disposed at a second radial distance from the center rotational axis. The jet is in direct fluid communication with the intake opening such that during operation of the fan assembly airflow is directed from the intake opening to the jet for reducing power required to operate the fan assembly.

Description

BACKGROUND

1. Field of the Invention

The present invention generally relates to fans for use in automotive or other technologies. More specifically, the present invention relates to a fan having at least one fan blade designed to reduce the power required to operate the fan.

2. Background Information

Many different types of fans are presently available. One popular type of fan is an axial flow fan, which blows air in an axial direction with respect to the axis of rotation of the fan blades. Axial flow fans are used in a wide variety of cooling applications such as in automotive or other technologies. Typically, a conventional axial flow fan has a hub with a center rotational axis and a plurality of fan blades that extend generally outward in a radial direction with respect to the center rotational axis of the hub. Each fan blade has two main surfaces (i.e., a leading surface and a trailing surface). The leading surface primarily contacts the air during rotation of the fan blades, thus moving the air. The trailing surface is opposite of the leading surface where the air is being sucked towards the fan blades. During operation of the fan, the leading surface of each blade has a combination of forces imparted thereon due to contacting the surrounding air. These combinations of forces create a resultant force that is opposite to the direction of rotation of the fan. Additionally, the rotation of the fan blades creates a low pressure region behind the distal ends of the trailing surfaces of the blades, which further increases the resultant forces. To operate the fan at a fixed speed, power equal to the resultant forces is required.

SUMMARY

It has been discovered that a reduction in the low pressure region behind the distal ends of the trailing surfaces of the fan blades can decrease the resultant forces acting on the fan blades. Thus, a fan assembly is proposed that seeks to reduce the power required to operate the fan by utilizing a flow channel to increase the pressure of the low pressure region behind the distal ends of the trailing surfaces of the fan blades.

In view of the state of the known technology, one aspect of the present invention is to provide a fan assembly that mainly comprises a center hub and a plurality of fan blades. The center hub has a center rotational axis. The fan blades extend from the center hub. Each of the fan blades has a leading surface and a trailing surface. The trailing surface of at least one of the fan blades includes an intake opening disposed at a first radial distance from the center rotational axis and a jet disposed at a second radial distance from the center rotational axis. The jet is in direct fluid communication with the intake opening such that during operation of the fan assembly airflow is directed from the intake opening to the jet to reduce power required to operate the fan assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of this original disclosure:

FIG. 1 is a left side elevational a vehicle equipped with a fan assembly in accordance with an illustrated embodiment;

FIG. 2 is an overall schematic of a vehicle engine with a coolant system including a fan, a radiator and a heater core;

FIG. 3 is a front (leading surface) side elevational view of the fan assembly in accordance with the illustrated embodiment;

FIG. 4 is a rear (trailing surface) side elevational view of the fan assembly in accordance with the illustrated embodiment;

FIG. 5 is an enlarged, rear (trailing surface) side elevational view of one of the fan blades in accordance with the illustrated embodiment;

FIG. 6 is an top edge view of the fan blade illustrated in FIG. 5 in accordance with the illustrated embodiment;

FIG. 7 is a transverse cross sectional view of the fan blade illustrated in FIG. 5 as seen along section line 7-7 of FIG. 5 at the intake opening;

FIG. 8 is a transverse cross sectional view of the fan blade illustrated in FIG. 5 as seen along section line 8-8 of FIG. 5 at a portion of the channel that provides direct fluid communication between the intake opening and the jet holes

FIG. 9 is a transverse cross sectional view of the fan blade illustrated in FIG. 5 as seen along section line 9-9 of FIG. 5 at one of the rows of the jet holes; and

FIG. 10 is a cross sectional view of the fan blade illustrated in FIG. 5 as seen along section line 10-10 of FIG. 5 to show the airflow through the fan blade.

DETAILED DESCRIPTION OF EMBODIMENTS

Selected embodiments will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

Referring initially to FIGS. 1 and 2, a vehicle 10 is illustrated that is equipped with a pair of fan assemblies 12 in accordance with an illustrated embodiment. As seen in FIG. 2, the fan assemblies 12 are part of a coolant based climate control system 14 for an engine 16. In this illustrated embodiment, one of the fan assembly 12 is driven by the engine 16 via a fluid coupling attached to the water pump pulley, while the other one of the fan assemblies 12 is driven by an electric motor. The parts of the coolant based climate control system 14, other than the assembly 12 are conventional components. In addition to the fan assemblies 12 and the engine 16, the coolant based coolant system 14 is mainly provided with, among other things, a compressor 18, a condenser 20, an expansion valve or orifice 22, an evaporator 24, a heater core 26 and a radiator 28. The compressor 18, the condenser 20, the expansion valve or orifice 22 and the evaporator 24 constitute a refrigerant circuit for the air conditioner of the vehicle 10. The engine 16, the heater core 26 and the radiator 28 constitutes a heater circuit for the heater of the vehicle 10. These components 16, 18, 20, 22, 24, 26 and 28 are conventional components that are well known in vehicles. Since these components 16, 18, 20, 22, 24, 26 and 28 are well known, the structures of the components 16, 18, 20, 22, 24, 26 and 28 will not be discussed or illustrated in detail herein.

The fan assembly 12 that is disposed in front of the condenser 20 is a “pusher fan” configuration, while the fan assembly 12 that is disposed in behind the radiator 28 is a “pulling or suction fan” configuration. In other words, the assembly 12 associated with the condenser 20 pushes air through the condenser 20, while the fan assembly 12 associated with the radiator 28 sucks air through the radiator 28.

Turning now to FIGS. 3 and 4, the fan assembly 12 is mainly provided with a center hub 30 and a plurality of fan blades 32. The center hub 30 has a center rotational axis A with the fan blades 32 rotating in a rotational direction R about the center rotational axis A. The fan blades 32 extend generally outward in a radial direction with respect to the center rotational axis A of the hub 30. The fan blades 32 extend from the center hub 30. Each of the fan blades 32 has a leading surface 34 (FIG. 3), a trailing surface 36 (FIG. 4), a hub end 38 and a distal or free end 40.

The leading surface 34 primarily contacts the air during rotation of the fan blades 32, thus moving the air. The trailing surface 36 is opposite of the leading surface 34 where the air is being sucked towards the fan blades 32. During operation of the fan assembly 12, the leading surface 34 of each blade 32 has a combination of forces imparted thereon due to contacting the surrounding air. These combinations of forces create a resultant force that is opposite to the direction of rotation of the fan assembly 12. Additionally, the rotation of the fan blades 32 creates a low pressure region behind the distal ends 40 of the trailing surfaces 36 of the blades 32, which further increases the resultant forces. To operate the fan assembly 12 at a fixed speed, power equal to the resultant forces is required.

As seen in FIG. 3, the trailing surface 36 of each of the fan blades 32 includes an intake opening 42 disposed at a first radial distance D1 from the center rotational axis A and a plurality of jet holes 44 disposed at a second radial distance D2 from the center rotational axis A. In the illustrated embodiment, the intake opening 42 is disposed on the trailing surface 36 of the blade 32 nearer to the hub 30 than the jet holes 44, which are located on the distal half of the trailing surface 36 of the blade 32. Preferably, the intake opening 42 is positioned adjacent the center hub 30. Each of the fan blades 32 further includes an airflow channel 46, which is disposed between the leading surface 34 and the trailing surface 36 of the corresponding one of the fan blades 32. The airflow channel 46 extends from the first radial distance D1 to the second radial distance D2 between the intake opening 42 and the jet holes 44. Thus, the airflow channel 46 provides direct fluid communication between the intake opening 42 and the jet holes 44. Each of the jet holes 44 has a smaller cross sectional area than a cross sectional area of the intake opening 42. Likewise, each of the jet holes 44 has a smaller cross sectional area than a cross sectional area of a airflow channel 46 that provides direct fluid communication between the intake opening 42 and the jet holes 44. In the illustrated embodiment, the diameters of the jet holes 44 in each row gets smaller or stays the same as the rows of the jet holes 44 approaches towards the center rotational axis A. Also in the illustrated embodiment, the number of the jet holes 44 in each row gets smaller or stays the same as the rows of the jet holes 44 approaches towards the center rotational axis A.

The jet holes 44 are in direct fluid communication with the intake opening 42 such that during operation of the fan assembly 12 airflow is directed from the intake opening 42 to the jet holes 44 to reduce power required to operate fan assembly 12. In other words, this arrangement of the jet holes 44 being in direct fluid communication with the intake opening 42 reduces the power required to operate the fan assembly 12. The reduction in power to operate the fan assembly 12 is due to the Bernoulli Effect, whereby air at a first location corresponding to the jet holes 44 with a higher rotational speed will have lower pressure than air at a second location corresponding to the intake opening 42 where the rotational speed is lower. By providing the airflow channel 46 within the blade 32, air flows from the high pressure area of the intake opening 42 to the lower pressure area of the jet holes 44. The air then flows out of the jet holes 44 to increase the air pressure in low pressure region that is behind the distal end 40 of the trailing surface 36 of the blade 32 to reduce the power needed to operate the fan assembly 12. This results in a reduction in the net aerodynamic drag on the fan blades 32 such that the fan blades 32 can deliver air more efficiently to the trailing blade 32 in its wake, which translates into less work in the process of generating airflow as compared to conventional designs.

In the illustrated embodiment, the fan blades 32 are all identical to each other. In other words, the locations and dimensions of the intake opening 42, the jet holes 44 and the airflow channel 46 are the same in each of the fan blades 32. However, it will be apparent to those skilled in the art from this disclosure that the fan blades 32 do not need to be all identical to each other. The number of the jet holes 44 can be different between each of the fan blades 32 as needed and/or desired. For example, a single jet (only one of the jet holes 32 can be in one of the fan blades 32 as needed and/or desired. Alternatively, only one or some of the fan blades 32 can be provided with an airflow passage (i.e., the intake opening 42, the jet holes 44 and the airflow channel 46). Also, while the jet holes 44 are circular holes in the illustrated embodiment, it will be apparent to those skilled in the art from this disclosure that the jet holes 44 can have other shapes as needed and/or desired. In the illustrated embodiment, the jet holes 44 are located on a distal half of the blade 32 with the jet holes 44 being spaced inwardly from the radially extending edges of the trailing surface 36.

In the illustrated embodiment, the fan blades 32 are mainly constructed of two pieces that are rigidly fixed together. For example, in the illustrated embodiment, each of the fan blades 32 includes a first blade part 50 entirely defining the leading surface 34 and a second blade part 52 entirely defining the trailing surface 36, with the first and second parts 50 and 52 being physically separate piece that are joined together in suitable manner. Also in the illustrated embodiment, each of the fan blades 32 is formed of a hard rigid plastic material such as those commonly used in automotive fan blades. When the fan blades 32 are formed with the first and second blade parts 50 and 52, the intake opening 42 and the jet holes 44 are preferably formed on the first blade part 50 of the fan blade 32, while the airflow channel 46 is preferably formed between an interface of the first and second blade parts 50 and 52. In this way, the airflow channel 46 can be easily formed.

Of course, it will be apparent to those skilled in the art from this disclosure that the fan blades 32 can be formed in other ways to produce the airflow passages (i.e., the intake openings 42, the jet holes 44 and the airflow channels 46). For example, although a two-piece construction is illustrated, it will be apparent to those skilled in the art from this disclosure that each of the fan blades 32 can be a unitary member (e.g., formed using conventional blow molding techniques).

While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. While the airflow channel 46 is disposed entirely within the fan blade 32, it will be apparent to those skilled in the art from this disclosure that the airflow channel 46 could even be formed on the trailing surface 36. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

Claims

1. A fan assembly comprising:

a center hub having a center rotational axis; and

a plurality of fan blades extending from the center hub, each of the fan blades having a leading surface and a trailing surface,

the trailing surface of at least one of the fan blades including an intake opening disposed at a first radial distance from the center rotational axis and a jet disposed at a second radial distance from the center rotational axis, with the jet being in direct fluid communication with the intake opening such that during operation of the fan assembly airflow is directed from the intake opening to the jet to reduce power required to operate the fan assembly.

2. The fan assembly as set forth in claim 1, wherein

the at least one of the fan blades further includes a channel that provides direct fluid communication between the intake opening and the jet.

3. The fan assembly as set forth in claim 2, wherein

the channel is disposed between the leading surface and the trailing surface of the at least one of the fan blades.

4. The fan assembly as set forth in claim 2, wherein

the channel extends from the first distance to the second distance.

5. The fan assembly as set forth in claim 1, wherein

the jet includes a plurality of jet holes.

6. The fan assembly as set forth in claim 5, wherein

the jet holes are circular holes.

7. The fan assembly as set forth in claim 5, wherein

the jet holes are located on a distal half of the blade.

8. The fan assembly as set forth in claim 5, wherein

the jet holes are spaced in from a radially extending edge of the trailing surface.

9. The fan assembly as set forth in claim 5, wherein

each of the jet holes has a smaller cross sectional area than a cross sectional area of the intake opening.

10. The fan assembly as set forth in claim 5, wherein

each of the jet holes has a smaller cross sectional area than a cross sectional area of a channel that provides direct fluid communication between the intake opening and the jet holes.

11. The fan assembly as set forth in claim 1, wherein

the intake opening is positioned adjacent the center hub.

12. The fan assembly as set forth in claim 11, wherein

the intake opening has a larger cross sectional area than a cross sectional area of the jet.

13. The fan assembly as set forth in claim 1, further comprises

each of the fan blades includes a corresponding intake opening disposed at a first radial distance from the center rotational axis and a corresponding jet extending from the center hub disposed at a second radial distance from the center rotational axis.

14. The fan assembly as set forth in claim 1, wherein

the at least one of the fan blades includes a first blade part defining the leading surface and a second blade part defining at least part of the trailing surface, with the first and second blade parts being physically separate pieces that are joined together.

15. The fan assembly as set forth in claim 14, wherein

the at least one of the fan blades further includes a channel that provides direct fluid communication between the intake opening and the jet, with the channel being formed between an interface of the first and second blade parts.

16. The fan assembly as set forth in claim 15, wherein

the jet is formed on the first blade part of the at least one of the fan blades.

17. The fan assembly as set forth in claim 15, wherein

the intake opening is formed on the first blade part of the at least one of the fan blades.