The present invention relates to an improvement in an air blowing device. Typically such a device incorporates a bladed fan wherein the blades are mounted on a shaft which is fitted into a motor for rotational purposes. The rotation of the shaft rotates the blades in order to create an air flow forward of the blades which rotate, to accelerate the air in front of the blades forward of the blade fan, while suction draws air from behind. Typically, such devices will be provided with grilles or grates surrounding the fan blades to avoid injury to the user. Such grilles or grates will also be provided with vanes or louvers which will direct the air stream from the radial and/or tangential components of the air flow toward the axial flow. It is also well known that the blades may be manufactured from metal, in which case, clearly a grille or grate of some type must be used to surround the blades to protect the user from any type of injury. The prior art similarly shows bladed fans wherein the fan blades are formed of a foam or plastic material, which minimizes injury to the user, and in the case of foam blades, permits the fan to be used without the need of a protective grille. However, all of such prior art devices require that the fan blades be mounted on a shaft which is in turn carried or mounted in a motor of some type, which operates to rotate the shaft, and it turn, the blades to create the air flow. Hence, all of the mechanisms necessary to create the air flow are exposed to the user, in one form or another.
Another form of prior art air blowing devices demonstrated in the prior art is especially shown in U.S. Pat. No. 2,488,467. The device as demonstrated in the foresaid patent is a motor driven fan and eliminates fan blades. In this instance, the fan consists of a base in which the motor is contained, the motor driving an impeller to create the air flow, the base extends upwardly via a neck portion, which has three distinct nozzles mounted to the upper portion of the neck, and each of which includes a hollow interior chamber, into which the air flow created by the motor's impeller will flow. Each of the nozzles are provided with a slot formed along the outer forward edge thereof, and which functions as an exit port for the air flow generated by the impeller of the motor. As indicated in the aforesaid patent, the device is intended to produce a uniform flow of air which may be regulated without changing the speed of the motor and which moves the moving elements including the motor and the impeller into an enclosed base, providing a safety feature for the user. Further note that the impeller here would spin much faster than the blades of a typical motor driven fan for ventilation. This gives the air flow a greater velocity even if the total flow rate were the same.
The prior art has advanced to a further improvement over the bladeless motor driven fan as shown in U.S. Pat. No. 2,488,467, as demonstrated by US patent application publication US 2009/0060710. This device makes use of the concept of a nozzle or housing which incorporates a Coand{hacek over (a)} surface adjacent to the slot opening of the housing or nozzle. As described in the aforesaid publication, the device includes a base which contains the motor and impeller device which creates the air flow, and exits the base into a circular housing or nozzle which has a hollow interior, and exits the housing interior toward the central axis via a slot formed along the periphery of the rear portion of the housing. As described in the aforesaid publication, the air discharge slot is formed adjacent to a curved or Coand{hacek over (a)} surface which is formed along the wall on the downstream side of the slot throughout. As indicated by the specification therein, the Coand{hacek over (a)} surface is intended to draw air from outside the fan assembly through the opening formed by the housing, by bending in a forward direction the air flow directed over the Coand{hacek over (a)} surface. As indicated therein, air exiting from the slot hugs the Coand{hacek over (a)} surface, expands downstream of the slot and this air stream will cause air from outside of the fan device to draw air through the central opening therein to produce an enhanced air flow forward of the air device. Again, as indicated therein, the primary air flow directed over the Coand{hacek over (a)} surface combined with the secondary air flow entrained by primary air flow acts as an air amplifier and gives a total air flow emitted or projected forward to a user from the opening defined by the nozzle. Hence, the total air flow is sufficient for the fan assembly to create an air current suitable for cooling.
A companion publication describes the relationship between the fan nozzle and the base as described in publication US 2009/0060711. It is stated therein that the base is no more than twice the depth of the nozzle and width of the base is no more than 75% the width of the nozzle. These relationships appear to permit the device to be made as small and as compact as possible due to space restrictions in domestic environments.
The present invention relates to a further improvement to the design of an air blowing device or ventilating device and acts like a conventional axial bladed fan without exposure to rotating blades in the same manner as the prior art referenced hereinabove. The present invention takes advantage of the principals of induction or entrainment wherein a jet of air directed into a volume of stationary air accelerates adjacent volumes of stationary air to increase or magnify the volume of moving air. However, the present invention avoids having to resort to Coand{hacek over (a)} effect flow to achieve this magnification, rather, using simpler methods of collimating and redirecting air flows to shape the velocity distribution of the discharged air stream. As demonstrated in the -710 and -711 prior art devices, the device employs a Coand{hacek over (a)} surface. The Coand{hacek over (a)} effect in fluid flow describes the tendency of a jet of air to appear to be attracted to convex solid surface as the jet passes near. This results in a pressure drop in the region between the jet and the surface drawing the jet toward the surface. The effect is used to bend the discharge of the jet from a nozzle toward an adjacent curved surface and has the effect of directing the stream of air forward. This stream induces the volume of still air within the annulus or open space of the nozzle to move forward by induction, giving the multiplier effect as claimed therein. It will be noted, however, that the single ring disclosed therein includes a slot or opening located toward the rear of the ring and designed with the Coand{hacek over (a)} surface so that the jet emerges almost parallel to the inside surface of the ring. This construction will cause the still air behind the annulus or opening of the nozzle to be induced to move forward once the air flow emanates from the slot of the nozzle.
In the previously mentioned prior art device of the -467 patent, it will be observed that the slot of each of the rings is located at the forward edge of each of the rings. The air jets out through the orifices or slots into an annular pattern of air stream through concentric streams as demonstrated in the aforesaid patent. The air streams will therefore diffuse radially outward and inward and merge forming a more typical bell shape distribution pattern of air flow that varies with radial distance from the center axis of the diffuser. The air flow exiting the nozzle will tend to separate out and not be collimated into a beam of air. The result of this construction is that the user of the fan will not feel a beam of cool air when utilizing the device.
The problem which exists with respect to the prior art devices is that the air flow may not be strong because there is too much of a transverse or radial flow of air relative to the central axis of the air flow stream. This results in weak air flow and inefficient operation. As far as the device shown in the -467 patent is concerned, the outer diffuser ring or nozzle will spray a good portion of its air stream outward and not forward as it lacks any kind of nozzle, guide or louvers downstream of the nozzles. The more the air stream expands laterally, the less force is felt by the user at a distance in front of the fan. As far as the device shown in the -710 and -711 prior art devices, the use of a Coanda effect surface means that the friction losses of the jet flowing along the surface of the air foil shaped diffuser reduces efficiency and the ultimate flow rate of air from the fan. Further, the Coand{hacek over (a)} effect cannot be scaled up to higher air flows without increasing the size of the diffuser.
Further with respect to the prior art devices mentioned hereinabove, the air flow generated by the impeller must make a sudden almost 90° turn when exiting from the base into the diffuser ring or nozzle and therefore suffers a head loss due to the air having to bend almost 90° to enter into the hollow chamber of each of the nozzles or diffuser rings. If one attempts to put a larger motor in order to move more air, the extra speed and size adds noise so that the motor driving the impeller must be slowed down in order to get into the range of noise accepted by the consumer and hence, a loss of performance in addition to a loss in efficiency.
The present invention is intended to provide an air blowing device which employs a ring or diffuser nozzle, which shall be termed herein as a housing, which is constructed to avoid the problems noted above. The device of the present invention avoids the need for having a Coand{hacek over (a)} surface, by moving the slot to the forward portion of the housing, and is constructed with a pair of inner and outer walls which are flat, but are constructed in a manner which has the net effect of collimating the air flow emitting therefrom into a beam of air thereby improving the cooling effect observed by the user thereof.
It is therefore the object of the present invention to provide an air blowing device the type generally described, which is formed by a base which incorporates a motor therein, driving an impeller to create an air flow. A housing is mounted on the top of the base, which incorporates a hollow chamber therein, so that air flow created by the motor and impeller can exit the chamber of the base and enter into the interior chamber of the housing. The housing is designed to be mounted on the base with angled branches so that the air flow emanating from the impeller as it enters the interior housing chamber is bent less than 70°, and preferably approximately 45°, in order to reduce the loss of the air pressure or air flow as the air enters into the housing chamber.
A further object of the present invention is to design the slot forming the air discharge opening adjacent the forward edge of the housing, the slot being formed by an outer extended side wall, and an inner shortened side wall, both of which are flat surfaces.
A further object of the present invention is to provide a device of the type described, wherein the base is formed as a chamber which contains a motor therein with an impeller to create the air flow, and wherein the base is surrounded by an outer chamber which has air ducts formed therein for feeding outside air into the base interior chamber. The outer chamber is provided with air inlet openings, to permit outside air to be drawn into the device when the impeller is activated. The outer chamber further serves the purpose of reducing the noise which emanates from the motor when in operation.
In conjunction with the foregoing object, a further object of the invention is to provide an air blowing device of the type described wherein the interior chamber of the base may further be provided with a noise reducing filter material mounted to the interior side walls of the chamber, so that the combination of the outer chamber and the noise reduction filter material, will greatly reduce the noise which emanates from the operation of the motor.
A further object of the invention is to provide an air blowing device of the type described wherein the housing mounted to the base takes the form of an inverted triangle having the apex of the triangle forming the two branches mounted to the base, and the base of the triangle forming the top portion of the subject device.
In conjunction of the foregoing object, a further object of the invention is to provide a device as the type described wherein the housing may take the form of a diamond shaped device. It is considered that any geometric configuration may be used so long as the branches when mounted to the base, will bend the air flow entering the housing to bend less than 90°, and preferably more on the order of only 45° when entering the interior chamber of the housing.
Further objects and advantages will best be understood by reference to the accompanying drawings taken in conjunction with the following specifications.
In summary, the present invention is intended as an improvement over prior art air blowing devices which improves the air flow emanating from the device by collimating the air flow emanating from the device into a beam of air to enhance the cooling effect felt by the user. This is accomplished by providing a device which consists of a base which has an interior chamber housing a motor which drives an impeller to create an air flow, and the base having suitable air inlet openings to take in outside air for the impeller to create an air flow. A housing structure is mounted to the top of the base, the housing structure being mounted at a connecting point. The housing has an internal chamber which is in fluid communication with the chamber of the base through the connection point. The housing is provided with a slot air discharge opening adjacent the forward edge of the housing, the slot being formed by an outer extended flat surface, and an inner shortened flat surface. Further, the housing will take the form of a triangle or other geometric shape wherein the branches of the housing being mounted to the base of the connection point, will form an angle with the base such that the air flow emanating from the impeller of the motor blowing up through the connection point into the housing will bend no more than and preferably around 45°. Hence, the housing will ideally take the shape of triangular structure the apex of the triangle forming the connection to the base at a connection point, and the base of the triangle forming top portion of the air blowing device. Alternatively, the housing may take the shape of a diamond shaped structure. It is to be considered within the scope of the present invention to employ any geometric shape which avoids air having to bend almost 90° when entering the housing or nozzle of the base.
The invention as illustrated in the following drawings wherein:
a is a cross sectional schematic view of a slot air discharge opening in accordance of the present invention, the slot being formed by an outer flat extended surface and a lower shortened flat surface, the slot air discharge opening formed adjacent the forward end of the housing;
b is comparison schematic view in cross section, showing a construction of the slot as shown of the device in
c is a further embodiment of an slot air discharge opening in cross section, of a possible alternative embodiment of the present invention wherein the outer flat surface wall of the slot is further extended, and the inner shortened flat surface is set further back from the forward edge of the housing;
With specific reference to
b illustrates the flow pattern of the slot formed in the rings 15, 16 and 17 of the prior art device illustrated in
c illustrates a further embodiment of the present invention, wherein the outer extended flat surface 41 is further extended than the inner shortened flat surface 42, which has the effect of having even more of the air flow to the interior side of the housing 34.
b represents the construction of the nozzle or housing of the air blowing device of the
Again with a view in
The construction of the base interior and the related upper housing is more clearly shown in
It will be appreciated that the outer chamber 54 not only directs the air flow into the interior chamber 51 of the base, but also serves the purpose of deadening the noise created by the motor 52. A further feature that helps in the noise deadening capacity of the device is the provision of the filter material mounted along the walls of the base interior chamber 51. The filter material 63 is porous in nature, and hence, may be mounted over the air duct 57 and affords the device to have the opportunity to still have an inflow of air to feed air to the impeller 53 when it is operational.
From the above description it will be appreciated that the air blowing device 30 of the present invention operates in much the same manner as prior art devices, but improves upon the same by the construction of the housing, which takes the form of either a triangular configuration, or another geometric shape such as a diamond shape configuration. As will be appreciated from
It will be appreciated from the above description that the present invention further improves upon the construction of an air blowing device which eliminates fan blades from the external portion of the device, and relies upon an internally housed motor with an impeller, to create an air flow and is formed with an air discharge opening formed near the portion of the fan device so that a beam of collimated air is formed to increase the effect of cooling upon the user.
While there has been described what is at present considered to be the preferred embodiment of the invention, further variations may be made without departing from the true spirit and scope of the invention and the claims appended hereto.