TECHNICAL FIELD 0001 The invention relates generally to roof ventilators and in particular to an enhanced wind-powered turbine roof ventilator.

BACKGROUND OF THE INVENTION 0002 Wind-powered turbine ventilators are widely used in a variety of ventilation applications. Turbine ventilators are especially suited for ventilation of the under-roof space of residential, commercial, and industrial buildings. The popularity of wind-driven turbine ventilators derives from their relatively small initial costs, low maintenance requirements, and negligible operating costs. 0003 Turbine ventilators reduce the cost of cooling a building by removing hot air from the under-roof space of a building. Because the effectiveness of a ventilator is a function of the amount of air the ventilator is able to remove from the ventilated space, it is desirable to increase the volume of air-flow through a ventilator. It is further desirable to increase airflow without increasing the size of the ventilation assembly, because larger ventilators are more expensive to manufacture, generally considered unaesthetic, and may take up otherwise useful space. 0004 One solution found in the prior art is to use an externally-powered fan to force air through the ventilator. However, the use of an external power source inherently makes the ventilation apparatus more complicated to manufacture, and more prone to malfunction; translating into higher production and maintenance costs. Use of an external power source also makes the ventilator more expensive to operate than a wind-powered ventilator. 0005 Another solution attempted in the prior art involves including a fan within the ventilation apparatus and connecting the fan by a rod directly to the wind-powered turbine. However, because the rotational speed of the turbine is relatively slow, the fan does not turn quickly enough to provide a sufficient increase in airflow.

SUMMARY OF THE INVENTION 0006 The invention relates to an improved ventilation apparatus comprising a fan which is coupled to a turbine so that rotation of the turbine results in rotation of the fan at a greater speed of rotation than the turbine.

BRIEF DESCRIPTION OF THE DRAWINGS 0007 For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, in which: 0008 FIG. 1 illustrates a ventilation apparatus; 0009 FIG. 2 illustrates a gear assembly which may be used in a ventilation assembly; 0010 FIG. 3 depicts a turbine which may be used in a ventilation assembly; and 0011 FIG. 4 depicts a fan which may be used in a ventilation assembly.

DETAILED DESCRIPTION 0012 Referring to the drawings, FIG. 1 shows a wind-powered turbine ventilator 100 embodying features of the present invention. In the embodiment shown in FIG. 1, the ventilator 100 includes a turbine 12 rotably mounted on a ventilation shaft 14, which extends from a ventilation port 19 in a roof 16. Flashing 13 is preferably used between the ventilation shaft 14 and the roof 16 to prevent precipitation from entering the building. The turbine 12 is preferably mounted to the ventilation shaft 14 using a plurality of support members 15, which extend from the outer perimeter of the ventilation shaft 14. The support members 15 are preferably connected at the opposite end to a bearing housing 17 at a point above the center of the turbine 12. The top of the turbine 12 is preferably rotably mounted in the bearing housing 17 so that the turbine 12 is rotably supported above the ventilation shaft 14 by the support members 15. A number of other methods of rotably mounting the turbine 12 above the ventilation shaft 14 are known in the art, and any method may be used which is effective for holding the turbine 12 in position above the ventilation shaft 14 while allowing rotational movement of the turbine 12. 0013 A fan 18 is positioned within or near the ventilation shaft 14, preferably near the ventilation port 19, and is preferably configured to force air from the ventilated space through the ventilation port 19. The fan 18 preferably is coupled to the turbine 12 so that rotation of the turbine 12 results in rotation of the fan 18. More preferably, the fan 18 is coupled to the turbine 12 so that rotation of the turbine 12 causes the fan to rotate at a greater speed of rotation than the turbine 12, preferably at a ratio of at least approximately 1.5:1, and, most preferably, at a ratio of about 15:1. The fan 18 is preferably coupled to the turbine 12 so that the fan 18 rotates in the same direction as the turbine, but may alternatively be configured to rotate in the opposite direction. 0014 Preferably, an axle 20 is mounted to the turbine ceiling 22, preferably near its center. The axle 20 preferably extends downward from the turbine ceiling 22, substantially in alignment with the axis of rotation of the turbine 12. The axle 20 is preferably fixed in position with respect to the turbine 12, so that the axle 20 rotates with the turbine 12. 0015 Referring to FIG. 2, the opposite end of the axle 20 is preferably configured to provide driving power to a gear assembly 24. The gear assembly 24 is preferably held in a fixed position relative to the ventilation shaft by one or more braces 26. The axle 20 is preferably connected by a coupler 31 to an input shaft 32, which preferably extends through a bearing housing 34. Toward the opposite end of the input shaft 32, a first gear 36 is preferably mounted to the input shaft 32. The first gear 36 is preferably configured to drive a second gear 38 mounted on a gear shaft 40. The gear shaft 40 is preferably rotably mounted in the gear assembly 24 housing. A third gear 42 is preferably mounted on the gear shaft 40, so that the third gear 42 turns in conjunction with the second gear 38. The third gear 42 is preferably configured to drive a fourth gear 44, which is preferably mounted on an upper end of an output shaft 46. 0016 Preferably, the circumference of the first gear 36 is approximately 4 times the circumference of the second gear 38. The circumference of the second gear 38 is preferably about the circumference of the third gear 42. The circumference of the third gear 42 is preferably about 4 times the circumference of the fourth gear 44. However, any gear size ratios may be used that is effective for rotating the fan 18 at a greater speed of rotation than that of the turbine 12. 0017 The output shaft 46 preferably extends through a second bearing housing 48 to the fan 18. The output shaft 46 is preferably used to drive the fan 18 and to provide support for the fan 18. Alternatively, the output shaft 46 may be used only to provide a driving force to the fan 18, and the fan 18 may be supported by another method, such as by use of additional braces (not shown) and a bearing assembly (not shown). 0018 Although the coupling mechanism shown in FIG. 2 and described above is the preferable coupling means, the fan 18 may alternatively be coupled to the turbine 12 by other means. For example, a drive axle to the gear housing could be configured to engage a the turbine 12 at a bottom rim 30, or the turbine 12 could be configured to drive a flywheel (not shown), which could in turn be used to drive a fan. Alternatively, the turbine 12 could be used to drive an electric generator (not shown), which could be used to generate electricity to drive an electric fan (not shown). In yet another embodiment, the fan 18 may be coupled to the turbine 12 by a hydraulic connection (not shown). In yet another embodiment, an external power source (not shown), such as solar power or commercially-available electricity, could be used in addition to wind power, to aid in ventilation when wind power is inadequate. Generally, any mechanism may be used for coupling the fan 18 to the turbine 12 that is effective for transferring energy from the turbine 12 to the fan 18 and for causing the fan to rotate at a greater rotational speed than the turbine 12. 0019 FIG. 3 depicts a fan that may be used in a ventilator embodying aspects of the present invention. Preferably, the fan 18 comprises a plurality of fan blades 52 attached to a fan hub 54. Preferably, the fan 18 has about four fan blades 52, although any number of fan blades 52 may be used. A hole 56 is preferably defined in the fan hub 54 and the hole 56 is preferably configured to receive an output shaft 46, as shown in FIG. 1. Many other fans, impellers, propellers, blowers, and the like are known in the prior art and may be used in the present invention. 0020 FIG. 4 illustrates a turbine that may be used in a turbine ventilator. The turbine 12 preferably comprises a plurality of turbine blades 64, attached at an upper end to a roof 62 and attached at a lower end to a rim 30. The turbine blades 64 are preferably curved outward from the center of the turbine 12, and are preferably positioned at an angle with respect to the circumference of the turbine 12. The turbine blades 64 are also preferably placed in close proximity to one another so that, in combination, the blades substantially prevent precipitation from entering the ventilation shaft 14. Alternatively, a separate cover (not shown) may be place over the ventilation shaft 14 to block precipitation, or precipitation may be allowed to enter the ventilation shaft 14 and then directed into a drain (not shown). Other turbine designs are known in the prior art and may be used in the present invention. 0021 Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.