Rotary kinetic fluid motors or pumps – With control means responsive to non-cyclic condition... – Centrifugally initiated valve controlling fluid flow in...
Reexamination Certificate
1998-10-28
2001-08-21
Verdier, Christopher (Department: 3745)
Rotary kinetic fluid motors or pumps
With control means responsive to non-cyclic condition...
Centrifugally initiated valve controlling fluid flow in...
C415S125000, C415S220000, C415S223000, C416S24700A, C417S359000, C417S362000, C454S259000, C074S003000, C074S105000, C074S108000
Reexamination Certificate
active
06276895
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to new and useful improvements in fans equipped with a shutter and designed for moving air into or out of a building and, more particularly, this invention relates to a fan associated with an automatic centrifugal mechanism, adapted for closing the shutter for keeping out wind, rain or other matter, when the fan is off.
2. Description of the Prior Art
Usually fans are provided with gravity shutters which, at low revolution of the fan, cannot operate efficiently because the air pressure head developed by the fan is not sufficient to keep them fully open. Moreover, during fan operation and particularly during storm weather the out-flowing air cause vibrations, noises and wear and significant pressure losses of the fan. In the past, attempts have been made to solve the various problems of said fans and said gravity shutters, whereby various centrifugal systems had been proposed. A description of the prior art known to the applicant, which is pertinent to the present application, may be found in the following Patents:
U.S. Pat. No. 4,217,816; U.S. Pat. No. 5,195,928; U.S. Pat. No. 5,288,202. In the arrangement described in U.S. Pat. No. 4,217,816, the fan comprises a shutter mechanism with two centrifugal masses that, upon rotation of the propeller, transmits an axial force to an axially reciprocating actuator. Said actuator comprises a steel rod guide sliding on a bushing.
The above system works with satisfaction for opening the shutter. However, for closing it, since at low revolutions the centrifugal forces become insignificant, but the gravity forces of the two centrifugal masses are substantially important, at each revolution of the propeller, as the two masses are vertically aligned, there is a significant friction force on said bushing and said steel rod guide may jam; therefore, the shutter will not close completely. The system described in U.S. Pat. No. 5,288,202 is similar to the previous described, therefore, the solution is not satisfactory, the friction forces are still present and the jamming of said centrifugal system is possible.
The centrifugal device described in U.S. Pat. No. 5,195,928 is well known to the applicant. Applicant developed in the past a similar mechanism using three equally spaced rotating masses and found that it works smoothly and with satisfaction, because the steel rod guide causing the aforesaid problems had been eliminated. However, this device is more expensive, comprises too many parts and joints. In addition, it requires a precise balancing and frequent maintenance.
While all the aforementioned mechanisms have the advantage to keep positively open the shutter. However, they have the disadvantage to have an axial reciprocating actuator rotatably connected to the shutter central vane. Thus, when the fan is operating, the vibrations of the propeller and of the centrifugal mechanisms are continuously transmitted to the shutter, causing undesirable noises and wear.
SUMMARY OF THE INVENTION
The longstanding need for a fan equipped with a shutter and an associated novel centrifugal mechanism engineered for continuous operation even at low speed, in highly dusty and corrosive atmospheres, is now fulfilled by the invention disclosed hereinafter and summarized as follows.
The improved fan of this invention comprises: a casing split into half sections having a first opening face, equipped with a self opening shutter assembly, consisting of a plurality of individual streamlined vanes and a central vane rotatably fitted to the fan casing and connected with two heavy tie rods, an orifice for guiding efficiently the air flow produced by the fan propeller, which comprises a plurality of radially extending blades designed for intake and exhaust. The fan casing further comprises a second face equipped with a safety screen and a central structural member adapted for holding an electric reversible motor and said propeller.
The novel centrifugal mechanism rotates with the fan propeller and reacts automatically to fan speed. It is simple in design, compact and it has a minimum number of parts and joints required for high precision and for preventing looseness and vibrations of the mechanism even after long term use.
In dust environments, the dust or other foreign matter are able to collect on the centrifugal mechanism; thus, it is desirable to have its components enclosed in a hermetic housing. The centrifugal shutter mechanism of this invention includes at least a pair of radial sliding masses equally spaced apart in respect to the fan axis and located inside said hermetic housing in a plan perpendicular to the fan axis. Said masses are operatively connected, by means of steel wire cables, to an axial sliding reciprocating actuator comprising an internal spring.
When the fan is rotated in either direction by said electric reversible motor, said centrifugal masses, as the fan reaches the minimum speed of operation slide radially by centrifugal force and pull the axial sliding reciprocating actuator away from the central vane of said shutter against the urge of said compression spring, whereby said reciprocating actuator gradually will free the central vane of said shutter, allowing the pair of heavy tie rods, to rotate said central vane in open position.
When the fan is stopped, the centrifugal forces of said pair of masses decrease, whereby said compression spring progressively expands and push said axial sliding reciprocating actuator against the shutter central vane, which is compelled to rotate gradually around its longitudinal axis in a closed vertical position. As a result, the pair of heavy tie rods rotates all shutter vanes in a closed vertical position.
The centrifugal shutter mechanism can operate for either direction of rotation and therefore the fan can be used for moving air in either direction into or out of a building.
OBJECTS OF THE INVENTION
The main object of this invention is to teach certain improvements made to a fan and associated shutter operating mechanism, whereby the shutter is maintained positively open, when the fan is operating and closed by a centrifugal mechanism and this without using any motor electric power.
Further object of this invention is to provide a versatile low cost fan having an improved compact and light casing of a relatively low cost, requiring minimal installation space and shipping volume.
A further object of the invention is to provide a safe centrifugal mechanism with masses totally enclosed, simple in construction, positive in operation, designed to function for long periods of time and in a very range of speeds without the usual frequent servicing and repairs.
REFERENCES:
patent: 1648796 (1927-11-01), Albrecht
patent: 2037250 (1936-04-01), MacDonald
patent: 2100439 (1937-11-01), Friedman
patent: 2265112 (1941-12-01), Davies
patent: 2335508 (1943-11-01), Gustafsson et al.
patent: 2468366 (1949-04-01), Habinski
patent: 3273788 (1966-09-01), Coward, Jr.
patent: 3482767 (1969-12-01), Reinkoester, Jr.
patent: 3917433 (1975-11-01), Tomitaka
patent: 4217816 (1980-08-01), Mancinelli
patent: 4265591 (1981-05-01), Gurbin
patent: 5195928 (1993-03-01), Gigola
patent: 5288202 (1994-02-01), Mancinelli
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