Electric motor muffler

Details Electric motor muffler Electric motor muffler

2001-08-20

2004-01-20

Lam, Thanh (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S058000, C310S059000

Reexamination Certificate

active

06680551

ABSTRACT:

This invention relates to a motor housing assembly including an air exhaust cone for creating laminar air flow, and including an air exhaust passageway for reducing noise created by the operation of the motor.
BACKGROUND OF THE INVENTION
Electric motors and appliances are most often cooled by an integral fan that blows air on or draws air over the motor during operation. Unfortunately, many of the cooling systems are inefficient, because air flow through the motor housing and across the motor is turbulent and, as a result, inefficient. The inefficiency may result in reduced cooling. Poor intake and exhaust air flow can cause overheating of a motor.
In addition to cooling the motor, the inefficient air flow and fan operation creates noise. An inefficient air flow particularly can create a substantial noise level. If an engineer tries to compensate for the poor cooling of a motor with a more powerful fan, then the result is to create even more noise.
It is known to try to increase air flow across the motor by diffusing exhaust air. In other words, the exhaust outlet is larger than the air inlet. Despite this design feature, turbulence of air flow still prevents a fan from being as efficient as possible.
Diffusing the exhaust air also reduces noise by slowing down the air flow. Another known method of trying to damp the noise from a motor is to use a sound absorbent material in an exhaust path. While sound absorbent material has some effect in reducing noise, it is not always practical to use, because it can make the exhaust path tighter, and therefore the air flow less efficient.
SUMMARY OF THE INVENTION
Accordingly, it is a feature of the present invention to solve the foregoing problems and provide a motor housing assembly that reduces noise and that also creates a more efficient air flow. The result is a more efficient cooling system that creates less noise than conventional electric motor housings.
In one embodiment, the invention includes a motor housing assembly adapted to contain a motor wherein the motor comprises a fan adapted to cool the motor by drawing air across it. The assembly comprises an air inlet port, a shroud to contain the motor within the housing and an air inlet passageway defining a path from the inlet port to the motor. The assembly further comprises an air outlet port and an air outlet passageway separated from the inlet passageway and defining a path from the motor to the outlet port. The assembly also comprises a cone mounted in the outlet passageway and adjacent the fan whereby air that is exhausted by the fan will flow in a laminar fashion around the cone and through the outlet passageway and outlet port. The cone may have a frusco-conical shape comprising a circular base, a circular top and a sidewall wherein the sidewall has a vertical cross-section with a convex curve. Still further, the inlet port and outlet port have cross-sectional areas that are substantially equal. The fan may comprise a central hub portion having a circular face, and the circular face may have substantially the same cross-sectional area as the circular top of the cone. Also, the diameter of the fan may be larger than the diameter of the circular base of the cone.
In another embodiment, the motor housing assembly is adapted to hold a motor wherein the motor comprises a fan adapted to cool the motor by drawing air across it. The assembly comprises an air outlet port and an air outlet passageway defining a path from the fan to the outlet port wherein the outlet passageway comprises a plurality of turns totaling at least 270° of direction change. The outlet passageway may further comprise walls padded with a sound-absorbing material. The passageway may comprise three different turns of at least 90° each.


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