Rotary kinetic fluid motors or pumps – With sound or vibratory wave absorbing or preventing means...
Reexamination Certificate
2001-01-30
2002-09-24
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
With sound or vibratory wave absorbing or preventing means...
C415S173100, C264S051000
Reexamination Certificate
active
06454527
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a noise reduction mechanism of a fan device and a molding method of porous damping material used therefor. More specifically, it relates to a noise reduction mechanism of a fan device used for engine cooling system of special-purpose vehicle including construction equipment such as excavator and other vehicles, and industrial cooling system.
2. Description of Related Art
Conventionally, in an engine cooling system of vehicles, coolant is circulated between the engine and radiator. In such cooling system, a fan is attached proximal to the radiator, so that heat is exchanged between cooling air sucked in by the fan and the coolant in the radiator to cool the engine by the coolant after heat exchange.
In the above, a fan shroud is provided around the fan to straighten flow of the cooling air passing through the radiator, thus enhancing heat exchange by the radiator to improve cooling efficiency of the engine.
A strong swirl is generated at a slight gap between an end of the fan and the fan shroud in accordance with rotation of the fan, which causes jet noise. For reducing the jet noise, it is disclosed in Japanese Utility Model Laid-Open Publication No. Sho 56-41119, Japanese Utility Model Laid-Open Publication No. Sho 57-126524, Japanese Utility Model Laid-Open Publication No. Sho 64-13229 and Japanese Utility Model Laid-Open Publication No. Hei 2-39956 (including microfilm of respective application in the publication) to provide a noise damper to the fan shroud.
All of the noise dampers disclosed in the publications have opposing surface of the fan shroud opposing the end of the fan formed of hard perforated metal with a lot of through-holes being drilled, so that the jet noise can be reduced by the damping material and energy damping space provided further outer side of the perforated metal.
However, according to the noise damper disclosed in the publications, since the perforated metal is used at the portion where the strong swirl is generated, high-frequency impulsive sound can be generated by an impact caused when the cooling air bumps into step portion of the through-holes of the perforated metal. Accordingly, though the noise damper can reduce the jet noise, the impulsive sound can be newly generated, thus being unable to effectively reduce the overall noise.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a noise reduction mechanism of a fan device capable of effectively damp both the impulsive sound and the jet noise caused by the swirl, thus effectively reduce the noise.
The noise reduction mechanism of fan device according to the present invention attains the above object by changing material of the member proximal and opposing to the end of the fan and/or structure around the fan (fan shroud).
Specifically, A noise reduction mechanism of fan device according to the present invention includes: a fan shroud spaced apart from a rotation locus of an end of a rotary fan by a predetermined gap; a shroud support for supporting the fan shroud; and a porous damping material opposing to the end of the fan, the porous damping material being attached to at least a part of the fan shroud or forming a part of the fan shroud.
In the present description, the word “porous” refers to a material having porosity, i.e. sponge-like material, which is different from the perforated metal having a number of holes drilled by press working.
In the present invention, since the porous damping material is attached to the surface (inner circumference) of the fan shroud opposing to the end of the fan to which the strong swirl is generated by pasting, or the surface of the fan shroud opposing to the end of the fan itself is made of the porous damping material, the jet noise caused by the swirl can be damped by sound absorbing properties of the porous damping material.
Further, since the conventional perforated metal is not used, the cooling air does not bump into the hard step portion, thus being unlikely to generate impulsive sound.
Accordingly, both of the impulsive sound and the jet noise can be effectively damped and the noise between the end of the fan and the fan shroud can be securely decreased.
The noise reduction mechanism of fan device according to the present invention may preferably have a radiator provided to upstream or downstream of the fan, a radiator hood and an end plate, the radiator hood and the end plate air-tightly connecting the radiator and the fan shroud.
According to the above arrangement, since the airtight space surrounded by the radiator hood and the end plate works as a damping space of the energy (pressure wave) of the noise, damping properties can be improved. Further, since the radiator hood is provided, the cooling air can flow more smoothly, so that the radiator can exchange the heat more efficiently.
In the above noise reduction mechanism of fan device, another porous damping material may preferably be attached to inner circumference of the radiator hood and/or inner circumference of the end plate.
Accordingly, since the porous damping material is attached to the inner circumference of the radiator hood and the end plate, the noise can be further decreased.
In the noise reduction mechanism of fan device according to the present invention, a number of holes may preferably be formed to the fan shroud with the porous damping material being attached.
Accordingly, low-frequency noise can be effectively decreased by forming the number of holes to the fan shroud.
In the noise reduction mechanism of fan device according to the present invention, the fan shroud and/or the porous damping material may preferably have bell-mouth shape.
According to the above arrangement, since the fan shroud and/or the porous damping material have bell-mouth shape, the cooling air can flow smoothly between the end of the fan and the fan shroud or the porous damping material, so that the generated jet noise can be reduced to further decrease the noise.
In the above, the porous damping material may have a cover portion for covering a surface thereof opposing to the end of the fan.
Accordingly, since the surface of the porous damping material is covered with the cover portion, absorption of water can be more securely prevented as compared to chemical water-repellant treatment on the surface of the porous damping material. Further, since the dust snapped by the fan does not-bump into the porous portion of the porous damping material, the porous damping material can be prevented from being degraded and damaged, so that weather resistance and durability can be improved.
Furthermore, since firmness of the porous damping material can be improved by the cover portion and the porous damping material is less likely to be flexed, the porous damping material is more easily attached to the fan shroud by, for instance, pasting, thus facilitating manufacture of the fan shroud.
In the noise reduction mechanism of fan device according to the present invention, the fan shroud may preferably have a protector for protecting at least one of upstream end and downstream end of the porous damping material in an air flow direction.
When the porous damping material is attached to the fan shroud, the upstream and downstream end of the porous damping material can be easily peeled off from the fan shroud by collision with the dust snapped by the fan. However, since the protector can prevent the collision of the dust, the porous damping material can be effectively prevented from being peeled off.
In the above, the fan shroud may preferably have an engage member for partially engaging the porous damping material.
Accordingly, since the engage member can maintain the attachment of the porous damping material, the porous damping material can be prevented from being peeled off from the fan shroud, thus improving reliability.
The fan shroud may have openings respectively provided on upstream and downstream side in the air flow direction and curved in bell-mouth shape, and a parallel portion provided between the open
Koshimizu Kengo
Nishiyama Toshihiko
Yabe Mitsuo
Armstrong Westerman & Hattori, LLP.
Kershteyn Igor
Komatsu Ltd.
Look Edward K.
LandOfFree
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