AIR CLEANER

Abstract: An air cleaner comprises a thin lightweight fan module 11 having a fan 111, a casing 112 containing said fan 111 therein and a housing 114 containing the casing 112 therein; a thin lightweight air filter module 12 having an air filter 121; and an air flow moderator 13 disposed between the fan module 11 and the air filter module 12, thereby providing a thin, lightweight and noiseless, air cleaner which has a high collection efficiency and an excellent ventilation ability.

Description: This invention relates to a thin lightweight noiseless air cleaner having a high collection efficiency and an air cleaning system using the same. A sufficiently purified environment is required in precision machinery industries for the production of semiconductors, pharmaceutical industries, hospitals, research institutes in the field of biotechnology, etc.. Depending on the situation air quality might need to be controlled in a single bench area, in a regulated booth or even in an entire room. Air purification has been acomplished by, for example, an air cleaning system such as the one shown in Figure 10 , which is composed of a plurality of filter units 100, each of which is fixed on supporters 400 from a ceiling (not shown). Spacers 500 and caulking compounds 600 must be positioned in the space between the filter units 100, making its installation complicated. The resulting sealing system is not enough to prevent a certain amount of air leakage. As shown in Figure 11, these units 100 may be installed on a ceiling by supporters 400, each of which has a rectangular frame 101. Although a gasket 601, such as a chloroprene sponge, is positioned between the filter frame 102 and the rectangular frame 101, air leakage therefrom cannot be avoided. Furthermore even the airtight connection 105 between the air filter module 103 and the fan module 104 in each unit 100 cannot prevent all air leakage. In addition, the filter module 103 and the fan module 104 constituting the above-mentioned filter unit 100 are large and heavy, so that the filter unit 100 is correspondingly bulky and heavy as a whole thereby. Subsequently, the unit is noisy, difficult to install, inspect and repair. Replacement of parts such as the fan, filter, etc., are difficult due to the size and weight. From US-A-4,319,899 there is known an air cleaner provided with a transition duct and a plenum chamber of a specific shape designed to slow down the air travelling from the fan outlet to the air filter inlet of the air cleaner by expansion. From US-A-3,780,503 there is known a clean air room, wherein each of a series of air filters served by a common air supply duct is provided with an air flow control valve containing moveable parts which allow the air flow through each of the air filters to be made equal. According to a first aspect of the present invention there is provided an air cleaner comprising a thin lightweight fan module having a fan, a casing containing said fan therein and a housing containing said casing therein; a thin lightweight air filter module having an air filter; and a physical air flow moderator board disposed parallel to the back face of the air filter module and between said fan module and said air filter module, the board being connected along three of its sides to the walls of the housing so as to define a flow path between the fan and the board and between the board and the air filter in such a manner that the flow path area in front of the outlet of the fan is not immediately connected to the flow path area between the board and the air filter. The casing is, in a preferred embodiment, eccentrically positioned within said housing of the fan module to create a large space in front of the outlet of said fan casing. According to a second aspect of the present invention there is provided an air cleaner comprising a pair of thin lightweight fan modules each of which has a fan, a casing containing said fan therein and a housing containing said casing therein; a pair of thin lightweight air filter modules each of which has an air filter; and a pair of physical air flow moderator boards each of which is disposed parallel to the back face of the air filter module and between said fan module and said air filter module, the board being connected along three of its sides to the walls of the housing so as to define a flow path between the fan and the board and between the board and the air filter in such a manner that the flow path area in front of the outlet of the fan is not immediately connected to the flow path area between the board and the air filter, wherein each of said casing is eccentrically positioned within said housing of the fan module to create a large space in front of the outlet of said fan casing, and said two each adjacent housings in which the fan casings face each other with respect to their outlets are divided by a partition in such a manner that the end portion of the outlet of the casing in the housing is connected by said partition to the end portion of the outlet of the other casing, thereby regulating the direction of each of the air flows from said fan casings. The housing is, in a preferred embodiment, provided with vibration and noise absorbers. The fan is preferably a propeller-type fan or a sirocco fan. The fan is, in a preferred embodiment, provided with a resonance prevention device at its back. The resonance prevention device is, in a preferred embodiment, a flywheel. Thus, the invention described herein is advantageous as it (1) provides an air cleaner which has a high collection efficiency and an excellent ventilation ability; (2) provides a noiseless air cleaner; (3) provides an air cleaner, which is thin and lightweight; (4) provides an air cleaner which produces a uniform rate of air flow; (5) provides a small-sized air cleaner which can be installed in a small space; and (6) provides an air cleaning system which is composed of the above-mentioned air cleaner and in which complete airtightness can be maintained. This invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawings as follows: Figures 1, 2 and 3, respectively, are a partly sectional back view, a partly sectional plan view and a partly sectional side view of the air cleaner of this invention. Figure 4 is a partly sectional back view of another air cleaner of this invention. Figures 5, 6 and 7, respectively, are a partly sectional back view, a partly sectional plan view and a partly sectional side view of another air cleaner of this invention. Figure 8 is a partly sectional back view of another air cleaner of this invention. Figure 9 is a partly sectional back view of another air cleaner of this invention. Figures 10 and 11, respectively, are partly sectional side views of a conventional air cleaning system. DESCRIPTION OF THE PREFERRED EMBODIMENTS Figures 1, 2 and 3 show an air cleaner 1 of this invention, which comprises a fan module 11 having a sirocco fan 111, a casing 112 containing the fan 111 therein and a housing 114 containing the casing 112 therein; and an air filter module 12 having an air filter 121. The thickness of the fan 111 (i.e., the thickness of the fan module 11 ) is 1/2 or less than that of the prior art, creating a thin air cleaner. The filter 121 has a collection efficiency of 99.97% with respect to dioctylphthalate particles of a size of 0.3 µm in a monodisperse system. An example of the filter 121 is an HEPA (High Efficiency Particulate Air) filter. The thickness of the filter module 12 containing such an HEPA filter is, for example, as thin as 100 mm or less, while that of a conventional filter module is 150 mm. A prefilter 14 can be positioned at the back of the fan 111 as desired. A guide vane 15 is positioned at each corner of the housing 114 to avoid turbulence from air discharged from the outlet 113 of the fan casing 112 as it collides with the wall 115 of the housing 114, forming a turbulent flow. The guide vane 15 can be a plastic board, etc., but is not limited thereto. The air flow from the outlet 113 of the fan casing 112 is not uniform with respect to dynamic pressure thereof in the whole region of the outlet 113, because the rate of the air flow within the circular duct within the casing 112 is greater along the inner diameter of the duct than along the outer diameter thereof. While the air flow, having an ununiform dynamic pressure, reaches the filter 121, passing through the significantly long path between the fan casing 112 and the housing 114, the dynamic pressure is gradually reduced to a static pressure. In order to make the path of the air flow longer, a moderator 13, such as a plastic board, etc. is positioned between the fan module 11 and the filter module 12. While the air flow which is not uniform with respect to the dynamic pressure passes through the moderator 13 and the filter module 12, the dynamic pressure is reduced to a static pressure. The air flow having a reduced dynamic pressure collides with the whole back face of the filter 121 and passes therethrough with a uniform distribution flow rate. Figure 4 shows another air cleaner 2, in which the casing 112 of the fan 111 is eccentrically positioned within the housing 114 of the fan module 11 to create a large space 110 in front of the outlet 113 of the casing 112. As soon as air is discharged from the casing 112 into the large space 110, its dynamic pressure is reduced forming a gentle flow, which, then, comes into the path between the moderator 13 and the filter module 12 to create an even more gently flow. Thus, this significantly gentle air flow is fed into the back face of the filter 121. Figures 5, 6 and 7 show another air cleaner 3 according to this invention, in which a pair of fan casings 112 are disposed facing each other with respect to their outlets 113. Each of the fan casings 112 is positioned in each of the two adjacent housings 114 which are divided by a partition 116 serving to prevent an interference of the air flow from the outlets 113 of the fan casings 112 and create a low level of noise from the air cleaner 3 . The noise produced by the air cleaner 3 provided with the partition 116 according to this invention was 50 dB(A), while that from an air cleaner having no partition was as high as 55 dB(A). Guide vanes 15, which are positioned at the corner of the housing 114, are effective to avoid an interference phenomenon deriving from the air discharged from the fan casings 112 . The partition 116 and the guide vane 15 may be made of plastics, etc., but are not limited thereto. This air cleaner 3 is also provided with a moderator 13 such as a plastic board, etc., which is positioned between the fan module 11 and the filter module 12, resulting in the reduced dynamic pressure of the air flow from the fan 111 for the same reasons as in the above-mentioned cleaner 1. Another air cleaner 4 is shown in Figure 8, wherein each of the fan casings 112 may be eccentrically positioned within the housing 114 to create a large space 110 before the outlet 113 of the fan casing 112, thereby allowing for the reduction of the dynamic pressure of the air flow from the outlet 113 of the fan casing 112 and resulting in a gentle flow having a static pressure. Then, the gentle flow comes into the path between the moderator 13 and the filter module 12, becoming even more gentle, and the resulting significantly gentle flow collides uniformly with the whole face of the filter 121 and passes through the filter 121. In order to enlarge the discharge space 110, as shown in Figure 9, the partition 116 may be positioned in such a manner to connect the end portion 117 of the outlet 113 of the fan casing 112 to the end portion 117 of the outlet 113 of the other casing 112. In this air cleaner 5, the air flow from each of the fans 111 reaches the filter 121 through a different path, that is, the air flow from the fan casing 112 is fed into the filter 121, passing through the path around the other casing 112.

Claims: An air cleaner comprising a thin lightweight fan module having a fan, a casing containing said fan therein and a housing containing said casing therein; a thin lightweight air filter module having an air filter; and a physical air flow moderator board disposed parallel to the back face of the air filter module and between said fan module and said air filter module, the board being connected along three of its sides to the walls of the housing so as to define a flow path between the fan and the board and between the board and the air filter in such a manner that the flow path area in front of the outlet of the fan is not immediately connected to the flow path area between the board and the air filter. An air cleaner according to claim 1, wherein said casing is eccentrically positioned within said housing of the fan module to create a large space in front of the outlet of said fan casing. An air cleaner comprising a pair of thin lightweight fan modules each of which has a fan, a casing containing said fan therein and a housing containing said casing therein; a pair of thin lightweight air filter modules each of which has an air filter; and a pair of physical air flow moderator boards each of which is disposed parallel to the back face of the air filter module and between said fan module and said air filter module, the board being connected along three of its sides to the walls of the housing so as to define a flow path between the fan and the board and between the board and the air filter in such a manner that the flow path area in front of the outlet of the fan is not immediately connected to the flow path area between the board and the air filter, wherein each of said casing is eccentrically positioned within said housing of the fan module to create a large space in front of the outlet of said fan casing, and said two each adjacent housings in which the fan casings face each other with respect to their outlets are divided by a partition in such a manner that the end portion of the outlet of the casing in the housing is connected by said partition to the end portion of the outlet of the other casing, thereby regulating the direction of each of the air flows from said fan casings. An air cleaner according to claim 1, wherein said housing of the fan module is provided with vibration and noise absorbers. An air cleaner according to claim 4, wherein said fan is a sirocco fan.

Inventors: METOKU, YOSHIHARU, NOBIRAKI, KOJI, OTSUKA, KAZUHIKO, TAMAKI, TOSHITAKA, URAGAMI, HISATO, YOSHIMURA, KEIJI
Applicants: NITTA CO., LTD.
Application year: 1984
Main classification: B01D46
IPC codes: B01D46, F24F13