Abstract
An airflow shaping enclosure is mounted to the rear of a cyclist riding a bicycle. The airflow shaping enclosure is wide at its front and tapers toward its rear, maintaining and shaping airflow streamlines behind the cyclist. The forward section of the airflow shaping enclosure is shaped to match the rear of the cyclist and to fill space behind the cyclist's buttocks, back, and calves. The rear section of the airflow shaping enclosure is shaped to form a streamlined extension of the cyclist's body. The airflow shaping enclosure fore-aft and height locations are adjustable to minimize the gap between the airflow shaping enclosure and the cyclist's buttocks, back, and thighs. The airflow shaping enclosure is configured to carry luggage.
Claims
1. An airflow shaping enclosure mounted behind a cyclist, the enclosure having a front width profile substantially matching a width of the cyclist's lower back, hips and buttocks, a front height substantially midway between the cyclist's waist and shoulder height, a shape tapered from a maximum area cross sectional area at a front to a minimum cross sectional area at a rear, and a top of the enclosure is located entirely above a plane defined by a back of the cyclist.
2. An airflow shaping enclosure mounted behind a cyclist, the enclosure having a front width profile substantially matching a width of the cyclist's lower back, hips and buttocks, a front height substantially midway between the cyclist's waist and shoulder height, a shape tapered from a maximum area cross sectional area at a front to a minimum cross sectional area at a rear, and the front has a convex shape facing airflow.
3. The airflow shaping enclosure of claim 2 or 1, wherein forward edges and corners are rounded.
4. The airflow shaping enclosure of claim 3, wherein the rear is truncated prior to completing a full taper to zero cross section to form a truncation.
5. The airflow shaping enclosure of claim 4 wherein the truncation includes an accessory mounting feature.
6. The airflow shaping enclosure of claim 3, wherein section of the enclosure below a bicycle seat is protruded forward to fill volume behind the cyclist's calves.
7. The airflow shaping enclosure of claim 6, wherein the protruded section is a separable unit.
8. The airflow shaping enclosure of claim 3, wherein the enclosure may be opened and its internal volume may be used for storage and transport of luggage.
9. The airflow shaping enclosure of claim 3 wherein the enclosure is mounted to the bicycle or to an accessory rack fixed to the bicycle.
10. The airflow shaping enclosure of claim 9 wherein the enclosure mounting consists of a cantilever beam mounted to a bicycle seat post.
11. The airflow shaping enclosure of claim 9 wherein the enclosure mounting to the bicycle is adjustable in height and in fore-aft position.
12. The airflow shaping enclosure of claim 11 wherein the enclosure is mounted via horizontal position adjustment means, the horizontal position adjustment means including a fixing means to lock the horizontal position.
13. The airflow shaping enclosure of claim 11 wherein the enclosure is mounted via vertical position adjustment means, the vertical position adjustment means including a fixing means to lock the vertical position.
14. The airflow shaping enclosure of claim 8 wherein a top of the enclosure comprises a cap which opens with respect to a substantially horizontal separation.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 illustrates 2-dimensional flow around a streamlined body.
(2) FIG. 2 illustrates 2-dimensional flow around a cylindrical body.
(3) FIG. 3 illustrates 2-dimensional flow around a pair of cylindrical bodies in tandem.
(4) FIG. 4 is a side view of a cyclist on a bicycle, and mid-plane flow contours.
(5) FIG. 5 is a rear view of 3-dimensional flow around a cyclist on a bicycle.
(6) FIG. 6A, is a side view of an airflow shaping enclosure mounted on a bicycle.
(7) FIG. 6B is an overhead view of an airflow shaping enclosure mounted on a bicycle.
(8) FIG. 6C is an oblique front view of an airflow shaping enclosure mounted on a bicycle.
(9) FIG. 6D is an oblique rear view of an airflow shaping enclosure mounted on a bicycle.
(10) FIG. 7 is an oblique rear view illustrating truncation of the tail of the airflow shaping enclosure and provision of a mounting feature on the truncated tail.
(11) FIG. 8 is an oblique front view illustrating attachment of the airflow shaping enclosure to the bicycle.
(12) FIG. 9 is a side view of the cyclist and airflow shaping enclosure, and mid-plane airflow.
(13) FIG. 10 is a rear view of 3-dimensional flow around the cyclist and airflow shaping enclosure.
(14) FIG. 11 is an oblique rear view illustrating an opening system for the airflow shaping enclosure.
DETAILED DESCRIPTION OF THE INVENTION
(15) The drawings begin with portrayals of key aspects fluid flow around simple objects, both streamlined and otherwise. These flow aspects are illustrated in 2-dimensional configurations for clarity and simplicity. Next are illustrated aspects of airflow around a cyclist. Following are illustrations of the invention, and the improved airflow conferred by the invention.
(16) FIG. 1 illustrates 2-dimensional flow around a streamlined body. The 2-dimensional configuration is illustrated as a basis for understanding the 3-dimensional flow of the invention. Free stream flow 102 is traveling toward and past the streamlined body 101. A streamlined body is an ideal configuration to establish a low-drag flow condition. A key characteristic of a streamlined body is attached flow 103, and minimal turbulence 104.
(17) FIG. 2 illustrates 2-dimensional flow around a cylinder. The 2-dimensional configuration is illustrated as a basis for understanding the 3-dimensional flow of the invention. Impinging free stream flow 202 meets the cylinder 201. Flow stays attached as it traverses the cylinder leading edge 203. Upon passing the cylinder maximum width, flow separation from the cylinder trailing side 204 occurs, and trailing vortices 205 occur in the wake of the cylinder. Vortices represent rotational energy which is transferred to the air. Transferred energy results in drag on the cylinder versus the free stream flow.
(18) FIG. 3 illustrates 2-dimensional flow around a pair of cylindrical bodies in tandem. The 2-dimensional configuration is illustrated as a basis for understanding the 3-dimensional flow of the invention. Impinging free stream flow 302 meets the leading cylinder 301. Flow is attached 303 at the leading cylinder leading edge. The situation up to this point is similar to flow around the single cylinder. In this configuration however, there is a trailing cylinder 304 following the leading cylinder. As flow passes the leading cylinder, it separates, resulting in some vortices 305 behind the leading cylinder. Flow which detached from the leading cylinder reattaches 306 to the surface of the trailing cylinder. In this combination of leading cylinder and trailing cylinder, trailing vortices 307 behind the trailing cylinder are smaller than in the single cylinder configuration
(19) FIG. 4 is a side view of flow around a cyclist 401 riding on a bicycle 402. In general the airflow around the cyclist is 3-dimensional and complex to illustrate. In this figure, for clarify of illustration, only the flow originating specifically on the medial plane of the cyclist is illustrated. The airflow remains attached 403 to the cyclist's back 404, but flow in the region of the cyclist's lower back 405 and buttocks 406 generates a trailing vortex 407.
(20) FIG. 5 is a rear view of 3-dimensional flow around a cyclist on a bicycle. Flow remains attached down the centerline of the cyclist's back 403. Flow meeting the left side of the cyclist's torso travels around the cyclist's left side and generates a clockwise trailing vortex 501. Flow meeting the right side of the cyclist's torso similarly generates a counterclockwise trailing vortex 502.
(21) FIG. 6A, FIG. 6B, FIG. 6C, FIG. 6D describe the configuration of an airflow shaping enclosure 601 attached to a bicycle 402. FIG. 6A illustrates leading face 602, rounding in the horizontal plane 603 blending between the leading face and the taper 604, and finally into a tail 605. FIG. 6B indicates rounding in the vertical plane 606 leading to the tail 605. FIG. 6B indicates a protrusion 607 under the seat. FIGS. 6C and 6D further illustrate the 3-dimensional form of the airflow shaping enclosure and its relationship to the bicycle.
(22) FIG. 7 illustrates truncation 702 of the tail of the airflow shaping enclosure 601. A accessory mounting feature 703 is attached to the truncation.
(23) FIG. 8 illustrates mounting of the airflow shaping enclosure 601. The bicycle seat tube 802 resides within the bicycle frame seat post tube 803. A bracket 804 is fixed to the seat post. The bracket is adjustable in height along the seat post. A cantilever beam 805 interfaces with the bracket and supports the airflow shaping enclosure. The airflow shaping enclosure position is adjustable in a fore-aft direction along the axis of the cantilever beam. Vertical fixing screws 806 on the bracket lock the bracket in position on the seat post. Horizontal fixing screws 807 lock the cantilever beam with respect to the bracket.
(24) FIG. 9 is a side view of airflow originating in the midplane around the cyclist 401 and airflow shaping enclosure 601. Due to the influence of the airflow shaping enclosure, the flow over the cyclist's back 901 remains attached along the combination of cyclist's back and airflow shaping enclosure, decreasing aerodynamic drag.
(25) FIG. 10 is a rear view of 3-dimensional flow around the cyclist 401 and airflow shaping enclosure 601. Left trailing vortex 1001 and right trailing vortex 1002 are smaller than the vortices occurring without benefit of the airflow shaping enclosure.
(26) FIG. 11 is an oblique rear view illustrating the airflow shaping enclosure 601 in an opened condition. The airflow shaping enclosure is composed of a lower base section 1101, and a cap section 1102. The sections interface through the base section edge 1103 and the cap section edge 1104.
