Brushing – scrubbing – and general cleaning – Machines – With air blast or suction
Reexamination Certificate
2002-01-24
2004-08-24
Snider, Theresa T. (Department: 1744)
Brushing, scrubbing, and general cleaning
Machines
With air blast or suction
C015S314000, C015S327600
Reexamination Certificate
active
06779228
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a central vacuum power unit and more particularly to a central vacuum power unit allowing to substantially reduce the level of noise emitted.
DESCRIPTION OF THE PRIOR ART
A central vacuum cleaner comprises a power unit usually installed permanently in an area of a building and one or more ducts are connected to vacuum system intlets provided in various zone all over said building. Said cleaner allows to clean any areas of said building with the use of a flexible hose or other debris recuperation device connected to said intlets. Said central vacuum power unit can be activated by mere insertion of the hose in one of saids inlets which is electrically wire to said unit, or by a switch provided on the hose or in the debris recuperation device, or by any other means.
Because habitable surfaces in recent buildings are optimized, a central vacuum power unit is frequently installed near a living space. However, said power unit generates high levels of noise. Therefore, it is necessary to make said power unit as quiet as possible. The prior art reveals the use of opened cells polyurethane foam inside a canister of a vacuum cleaner, as sound absorbing material, the use of a muffler at the outlet of the working air; the flowing of sound through a tortuous passageway to generate sound reflection against sound absorbing material, the mounting of a motor on a seat made of vibration absorbing material, ect. Even with those characteristics intended to reduce the levels of noise emitted by existing central vacuum power unit, there is still a strong need for a more quiet central vacuum power unit for central vacuum cleaner.
More particularly, the prior art central vacuum power units suggest for reducing the level of noise generated at a vacuum air exhaust, to mount a straight silencer (muffler) to said exhaust of the working air. Preferably, it may be advantageous to provide an elbow between the an exhaust and the silencer to redirect the exhaust from a horizontal to a vertical direction and thereby to take less horizontal space (which is normally what is paid for in a building, ($/sq.ft)). Two problems arise in the prior art:
The use of a straight silencer fails to generate a sufficient amount of reflexion of said noise against a sound absorbing material and therefore a substantial level of noise is still emitted outside the central vacuum power unit.
The positioning of an elbow outside a canister of said central vacuum power unit creates an abrupt change in air direction that generates noise that is transmitted throught the sidewall of the elbow. This noise is not dampened in existing central vacuum power unit. Especially, when a tangential fan is used, the level of noise generated in the area of the elbow is important. Therefore, there is still a strong need fo find a simple and efficient way to reduce this prior art noise problem, especially to reach noise level lower than those of the existing prior art central vacuum power unit
It is to be noted that to seal leaks of noise originating from the opening around the working air exhaust, it is not possible to have a seal having at once no noises leaks and substantial surface properties (to block the noise) while remaining flexible. A more dense seal is generally less flexible. However, it is important to maintain the flexibility properties to avoid a rigid contact of the working air exhaust with the canister to avoid vibration and generating additional noise.
More particularly, said noise in the area of said elbow appears to have three origines, that is:
Opening around the fan outlet. Indeed, it was noted that even a very small opening will let considerable amount of noise escaping from the canister. Also, any vertical movement of the motor-fan assembly due to the vacuum underneath said assembly, contribute to increase the risk of having a solid contact with a structural part of the power unit to thereby transmit vibrations to said structure and generate additional noises (i.e. sound moves through the structure of the canister toward the outside)
Turbulence generated in said elbow (toward the outlet of the silencer). The zone of turbulence being near said silencer, the possibility of contact of the noise with a sound absorbing material is lowered.
Turbulence generated in the elbow (across the sidewall of the elbow) Standard elbow available in the industry are not provided with sound insulation and are generally made of light material such as polyvinyl chloride (PVC). They will let substantial amount of noise to propagate across its sidewall. Said sidewall has a low surface density and has low sound dampening properties.
It has now been discovered that the level of noises emitted by a central vacuum power unit for a central vacuum cleaner can be lowered, and preferably without affecting the efficiency and useful life of said power unit.
SUMMARY OF THE INVENTION
Advantageously, the present invention relates to a new central vacuum power unit, especially for a central vacuum cleaning system, said central vacuum power unit emitting substantially low level of noise outside in the surrounding environment Preferably, said level of noise are lower than those noted with existing central vacuum power unit
Advantageously, the present invention relates to a new central vacuum power unit, especially for a central vacuum cleaning system, in which the working air and noise (preferably at the fan exhaust) is subjected to at least one change of direction inside an acoustic dampening chamber, preferably to increase the amount of reflexions of the noise against sound absorbing material provided inside said acoustic dampening chamber.
Advantageously, the present invention relates to a new central vacuum power unit, especially for a central vacuum cleaning system, in which it is not necessary to use any outer silencer (muffler) or an elbow-silencer assembly at the working air exhaust of the power unit.
Advantageously, the present invention relates to a new central vacuum power unit, especially for a central vacuum cleaning system, that is simple, reliable and economical to manufacture
Advantageously, the present invention relates to a new central vacuum power unit, especially for a central vacuum cleaning system, that is very easy to install on a wall.
Advantageously, the present invention relates to a new central vacuum power unit, especially for a central vacuum cleaning system, in which the vacuum is a tangential vacuum fan, especially of the type having an axial air intake and a tangential air exhaust. Preferably, such a vacuum fan allow to generate an important vacuum and an important flow of working air
According to a particularly prefered embodiment of the invention, it has been surprisingly found that all important reduction of the level of noise emitted by a central vacuum power unit is obtained when the assembly is not positioned in the center of the canister, when the outlet of the fan enters a substantially annular acoustic dampening chamber and when the noise originating from the vacuum tangential fan has a change of direction and several absorption against a lining of sound absorbing material provided in said substantially annular acoustic dampening chamber.
According to another particularly preferred embodiment of the invention, means are provided to avoid the plate supporting the motor-fan assembly to tilt under the force resulting of the presence of a vacuum underneath the motor-fan assembly.
According to another particularly preferred embodiment of the invention, the motor-fan assembly and the piping at ist outlet do not have solid contact with the plate and/or canister supporting it, to thus prevent the transmission of vibration through the structure of the central vacuum power unit and thereby the gereration of noise.
According to another particularly preferred embodiment of the invention, the motor-fan assembly is centered to rest freely on a seat of vibration absorbing material thanks to a ring of vibration absorbing material retained in place by a ring of solid material making an integral par
Bizier Reynald
Cloutier Jacques
Plomteux Alexandre
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