Patent Grant
6899515
This application claims the benefit of the Korean Application No. P2002-20677 filed on Apr. 16, 2002, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to cross flow fans and air conditioners, and more particularly, to a cross flow fan with more than two unit successive fans, and an air conditioner fitted with the same.
2. Background of the Related Art
The air conditioner is an appliance for cooling/heating a room by using heat absorption/discharge from/to an environment in phase change of a working fluid.
In general, the air conditioner is provided with an indoor unit and an outdoor unit. The outdoor unit is provided with an outdoor heat exchanger, an outdoor fan, and a compressor, and the indoor unit is provided with an indoor heat exchanger and a fan.
The compressor, the outdoor heat exchanger, and the indoor heat exchanger are connected with refrigerant pipe, and the refrigerant circulates the compressor, the outdoor heat exchanger, the indoor heat exchanger, and the compressor in succession through the refrigerant pipe. The indoor heat exchanger produces cold air as the refrigerant evaporates at the indoor heat exchanger and absorbs heat from an environment, which cold air is discharged to a room space by the fan, to cool down the room.
The fan fitted to the indoor unit of the air conditioner draws air through an inlet and discharge through an outlet. The air drawn into the indoor unit through the inlet is deprived of heat to become cold air as the air passes through the indoor heat exchanger, and discharged to the room space through the outlet.
Meanwhile, the fans employed for the air conditioners are sirocco fans, propeller fans, turbo fans, and cross flow fans, wherein the cross flow fans are mostly used in small sized air conditioners each having the indoor unit and the outdoor unit separated from each other.
The cross flow fan is provided with an annular rim, and a plurality of impellers arranged along a circumference of, and vertical to the rim. The cross flow fan is fitted to the indoor unit, so that the impellers draw air at an inlet side in a circumferential direction and discharge the air in the circumferential direction at an outlet side in the circumferential direction as the impellers are rotated.
In the meantime, a pressure around the impeller is varied with time at fixed intervals as the impellers rotate. Particularly, when the cross flow fan is rotated, there are sharp periodic variations of pressures in parts adjacent to a stabilizer and a rear guide. The periodic pressure variation causes noise at a particular frequency, according to which principle, loud noise emits from the cross flow fan fitted to the indoor unit at particular frequencies as shown in FIG. 1. For reference,
Consequently, a supplementary design of the cross flow fan is required for improving a problem of causing significantly high noises at particular frequencies when the cross flow fan rotates.
Accordingly, the present invention is directed to a cross flow fan, and an air conditioner fitted with the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a cross flow fan, and an air conditioner fitted with the same, in which an amplitude of the period variation of environment pressure occurred during rotation of the cross flow fan is reduced for prevention of a high sound pressure generated at a particular frequency.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the cross flow fan includes a plurality of unit fans assembled side by side in succession twisted from each other, wherein the unit fan includes an annular rim, and a plurality of impellers arranged on a side of the rim vertical to, and along a circumference of the rim.
In another aspect of the present invention, there is provided a cross flow fan having a plurality of unit fans assembled in a length direction in succession, wherein the unit fan includes an annular rim, and a plurality of impellers arranged on a side of the rim vertical to, and along a circumference of the rim, wherein the impellers of the unit fan is assembled such that imaginary horizontal extension lines from the impellers of the unit fan have a phase difference with the extension lines from the impellers of an adjacent unit fan.
In further aspect of the present invention, there is provided an air conditioner including a casing having an inlet and an outlet, an indoor unit including an indoor heat exchanger provided in rear of the inlet inside of the casing, and a cross flow fan having a plurality of unit fans assembled at sides in succession, with the unit fans twisted from each other, cross flow fan being provided inside of the casing, and an outdoor unit having an outdoor heat exchanger and a compressor, the outdoor unit connected to the indoor unit with refrigent pipe. The unit fan has an annular rim, and a plurality of impellers arranged on a side of the rim vertical to, and along a circumference of the rim
The plurality of unit fans are assembled, for an example, by a predetermined twist angle it goes in a clockwise or anti-clockwise direction when the unit fans are seen from a side.
The plurality of unit fans are assembled, as another example, with a twist angle different from each other when the unit fans are seen from a side.
The impellers are arranged on the rim, for an example, at equal distances along a circumference of the rim, or the impellers are arranged on the rim, as another example, at unequal distances along a circumference of the rim.
The twist angle of the unit fan and a number of impellers have, for example, the following relation:
−0.18Z+11.43<δ<−0.18Z+11.633, where, Z denotes a number of impellers, and δ denotes the twist angle.
The twist angle between the unit fans when the unit fan has 30 impellers is, for an example, 6.05°˜6.25°. The twist angle between the unit fans when the unit fan has 31 impellers is, for an example, 5.85°˜6.05°. The twist angle between the unit fans when the unit fan has 32 impellers is, for an example, 5.65°˜5.85°. The twist angle between the unit fans when the unit fan has 33 impellers is, for an example, 5.50°˜5.70°. The twist angle between the unit fans when the unit fan has 34 impellers is, for an example, 5.30°˜5.50°. The twist angle between the unit fans when the unit fan has 35 impellers is, for an example, 5.15°˜5.35°.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention:
In the drawings:
The cross flow fan of the present invention has a plurality of stages, i.e., a plurality of unit fans are assembled in succession to form one cross flow fan. Though a related art cross flow fan has unit fans assembled such that extension lines of impellers coincide, the cross flow fan of the present invention has unit fans assembled such that the unit fans are twisted to each other, or extension lines of impellers does not coincide.
Once the cross flow fan is assembled thus, the environmental periodic pressure variation occurred when the cross flow fan is in operation can be reduced, enabling removal of a sound pressure peak occurred at a particular frequency, which reduces the noise generated when the cross flow fan is rotated. That is, by dispersing the periodic noise at the particular frequency to adjacent frequencies, the sound pressure peak, along with the noise, can be reduced.
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In describing the embodiments of the present invention, same parts will be given the same names and reference symbols, and repetitive description of which will be omitted.
Referring to
Referring to
Referring to
Meanwhile, the present invention provides the following structure for easy assembly of the unit fans 11.
When the rim 13 is fitted to both ends of the impeller 12, to form one unit fan 11, the rim at the left end of the impeller 12 is provided with a projection (not shown), and the rim at the right end of the impeller 12 is provided with a groove (not shown) for receiving the projection. Thus, once the projection and the groove are provided to each rim which is to be fitted to ends of the impeller 12, accurate assembly positions can be found easily by inserting the projection into the groove in assembly of the plurality of unit fans 11. Of course, it is required that the projections and the grooves are provided to positions taking the twist angles of the unit fans 11 into account.
In the meantime, a structure slightly different from above can be provided. In a case the rim 13 is attached to one end of the impeller 12, what is only required is formation of impeller grooves (not shown) in opposite sides of the rim 13 at positions different from each other for fitting the impellers 12. That is, what is only required is that the impeller grooves are provided to a left surface of the rim 13 for inserting and fastening the impellers 12, and other impeller grooves are provided to a right surface of the rim 13 such that the impeller grooves in the right surface have a phase difference from the impeller grooves in the left surface. If the impeller grooves in opposite sides of the rim 13 have a phase difference from each other respectively, the impellers 12 of one of the unit fans 11 have the phase differences from the impellers 12 of an adjacent unit fan 11 automatically when the impellers 12 are fitted to the impeller grooves in the rim 13.
Once the foregoing structure is provided, the assembly is very convenient and productivity is improved, as the unit fans 11 can be assembly with easy.
In the meantime, in the cross flow fan of the present invention, there can be an embodiment other than the embodiment in which the unit fans 11 are assembled with the unit fans 11 twisted to each other. That is, all the unit fans 11 are assembled into one cross flow fan, such that imaginary horizontal extension lines from the impellers 12 of the unit fan 11 have a phase difference with the same from the impellers 12 of an adjacent unit fan 11. In this instances, the phase difference may be represented with ΔL as shown in FIG. 4. Thus, if the extensions lines of the impellers 12 of the unit fans 11 do not coincide, which reduces the environmental periodic sound pressure variation occurred in rotation of the cross flow fan, leading to remove the sound pressure peak occurred at a particular frequency, the object of the present invention can be achieved.
Thus, the rims 13 are provided at both longitudinal ends of the cross flow fan 10 of an assembly of a plurality of unit fans 11. In
In the meantime, the air conditioner of the present invention includes an indoor unit and an outdoor unit. The indoor unit includes a casing, an indoor heat exchanger, a cross flow fan, and the outdoor unit includes an outdoor heat exchanger and a compressor. The indoor unit and the outdoor unit are connected with refrigerant pipe.
The casing of the indoor unit includes an inlet 21 and an outlet 22. As shown in
Referring to
In the air conditioner with the foregoing indoor unit, the refrigerant flows through the compressor of the outdoor unit, the outdoor heat exchanger, the indoor heat exchanger, and the compressor of the indoor unit in succession. In this instance, the refrigerant compressed to a high pressure at the compressor dissipates condensing heat at the outdoor heat exchanger to condense into a liquid phase, and transferred to the indoor heat exchanger of the indoor unit. The refrigerant transferred to the indoor heat exchanger 30 heat exchanges with the air introduced through the inlet 30 and vaporizes at the indoor heat exchanger 30, when the air introduced into the inlet 21 is cooled as a heat of the vaporization is absorbed from the air. The cooled air is supplied to a room through the outlet 22 and cools the room. The refrigerant passed through the indoor heat exchanger 30 is introduced into the compressor, and repeats the foregoing process, to cool down the room. Opposite to this, if the refrigerant is circulated in opposite direction in the air conditioner after a few elements are added to the air conditioner, the refrigerant absorbs heat at the outdoor heat exchanger, and dissipates condensing heat at the indoor heat exchanger. If the heat dissipated from the indoor heat exchanger is discharged to the room by rotating the cross flow fan 10, the air conditioner acts as a room heater. Because an air conditioning system which can cool or heat a room is in general used widely, the specification omits any further description of the air conditioning system.
In the meantime, the present invention suggests providing an optimal twist angle between unit fans 11 in the foregoing cross flow fan of the air conditioner, which will be described.
The particular frequency (BPF=blade passing frequency) at which the peak sound pressure occurs during rotation of the cross flow fan 10 can be defined as the following equation:
where, ‘N’ denotes revolutions per minute, and ‘Z’ denotes a number of impellers.
From the equation, it can be known that the BPF is proportional to the revolution per minute and the number of impellers.
In the meantime, the peak sound pressure at the BPF is derived as a function of the number of impellers, the twist angle between the unit fans, a length of the unit fan, and a number of the unit fans. In the present invention, a computer simulation is conducted using above parameters, to derive an optimal twist angle between the unit fans 11. The computer simulation is conducted based on 30˜35 impellers 12 in the unit fan 11.
A result of the computer simulation is shown in a table illustrated in FIG. 6. That is, the twist angle δ deg. between the unit fans 11 when the unit fan 11 has 30 impellers is 6.05°˜6.25°, the twist angle δ deg. when the unit fan 11 has 31 impellers is 5.85°˜6.05°, the twist angle δ deg. when the unit fan 11 has 32 impellers is 5.65°˜5.85°, the twist angle δ deg. when the unit fan 11 has 33 impellers is 5.50°˜5.70°, the twist angle δ deg. when the unit fan 11 has 34 impellers is 5.30°˜5.50°, and the twist angle δ deg. when the unit fan 11 has 35 impellers is 5.15°˜5.35°.
In the meantime,
As a result of the computer simulation, it is known that the length of the unit fan and the number of unit fans have little influence to the result. It is also known that the arrangements of the impellers either in equal pitches or unequal pitches have little influence to the result. Eventually, the result of the computer simulation for the twist angle δ deg. between the unit fans 11 can be simplified as a function of the number of impeller ‘Z’ as the following simple inequality.
−0.18Z+11.43<δ<−0.18Z+11.633
In the meantime,
Thus, the cross flow fan of the present invention can eliminate the noises generated at particular frequencies effectively by assembling the unit fans such that the unit fans are twisted to each other or extension lines of the impellers of the unit fan has a phase difference from extension lines of the impellers of an adjacent unit fan, which reduces the environmental periodic sound pressure variation when the cross flow fan rotates, and removes the peak sound pressure.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2002-0020677 | Apr 2002 | KR | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5573059 | Hamamoto et al. | Nov 1996 | A |
| 5611667 | Nagamori et al. | Mar 1997 | A |
| 6026103 | Oliver et al. | Feb 2000 | A |
| 6149381 | Lee | Nov 2000 | A |
| 6345951 | Choi | Feb 2002 | B1 |
| Number | Date | Country |
|---|---|---|
| 1118843 | Mar 1997 | CN |
| Number | Date | Country | |
|---|---|---|---|
| 20030194311 A1 | Oct 2003 | US |
