Air deflector for tractor-trailer vehicle

In combination, a tractor-trailer vehicle including a tractor having a cab with a roof and a trailer connected to the rear of the tractor and being towed thereby, the trailer having a front wall which extends up to a level above that of the roof of the tractor cab, a supporting structure secured to the top of the cab roof, and air deflector carried by said supporting structure and providing a frontwardly facing air-deflecting surface for reducing air resistance to forward movement of the tractor-trailer vehicle;

• wherein the improvement comprises:
• A. said air-deflecting surface is totally curved and forwardly convex in all its horizontal and vertical cross-sectional planes and is symmetrical about a vertical center plane and has a central portion and a pair of lateral wing portions symmetrically located on opposite sides of said central portion;
• B. said deflector has a top edge of substantially circular curvature and a base edge of elliptical curvature substantially conforming to the equation ##EQU4## inches, wherein x varies between about 34 and 69 inches;
• C. the base edge curve in the middle region thereof over an arc distance of about 20.degree. on either side of the midpoint of said base edge curve, corresponding to said central portion of sair air-deflecting surface, and the top edge curve over substantially its entire extent, each has a radius of curvature of about 74 inches;
• D. said base edge curve in each of the lateral end regions thereof on either side of said middle region, corresponding to said wing portions of said air-deflecting surface, has a radius of curvature of about 20 inches;
• and
• E. said air-deflecting surface is defined by (1) a generation of said middle region of said base edge curve upwardly and rearwardly through an angle of about 34.degree. to said top edge curve, with the center of curvature of the so-generated central portion of said air-deflecting surface being located on a plane that is parallel to the plane of said base edge curve and below the level of the cab roof, the perpendicular distance between said planes being the product of (a) the 74 inch radius of curvature extending from said center of curvature to said base edge curve and (b) the sine of an angle of about 12 to 16.degree. included between that radius and the lower one of said planes, and (2) a generation of said lateral end regions of said base edge curve through said angle of about 34.degree. with gradually increasing radii of curvature until at said top edge the radii of curvature of said wing portions are merged into and become equal to the radius of curvature of said central portion;
• and
• F. said supporting structure is arranged to orient said deflector so as to have a height, as measured vertically between two horizontal planes each tangent to a respective one of said top and base edges at the mid-point thereof, that is a function of the ratio of (1) the difference in height between the trailer front wall and the tractor cab roof to (2) the horizontal spacing between the rear of the cab and the front wall of the trailer;
• G. whereby, when the tractor-trailer vehicle is in motion, said deflector is effective to reduce separation of air at the front of the trailer and to prevent stagnation of air at the front of said air-deflecting surface.

An air deflector suitable for mounting on the roof of a cab of a tractor of a tractor-trailer vehicle and providing a frontwardly facing air-deflecting surface for reducing air resistance to forward movement of the tractor-trailer vehicle, wherein the improvement comprises:

• A. said air-deflecting surface is (1) symmetrical about a vertical center plane and has a central portion and a pair of lateral wing portions symmetrically located on opposite sides of said central portion, (2) is totally curved and forwardly convex in all its horizontal and vertical cross-sectional planes, and (3) in said central portion has a uniform radius of curvature in all horizontal and vertical cross-sectional planes;
• B. said deflector has a top edge and a base edge;
• C. the center of curvature of said central portion of said air-deflecting surface is located on a plane that is parallel to the plane of said base edge of said deflector and below the same, the perpendicular distance between said planes being the product of (a) the radius of curvature extending from said center of curvature to said base edge and (b) the sine of an angle of about 12.degree. to 16.degree. included between that radius and the lower one of said planes;
• and
• D. the radii of curvature of said wing portions of said air-deflecting surface are smaller at said base edge than said radius of curvature of said central portion and gradually increase until at said top edge the radii of curvature of said wing portions are merged into and become equal to the radius of curvature of said central portion.

An air deflector assembly suitable for mounting on the roof of a cab of a tractor of a tractor-trailer vehicle and including an air deflector providing a frontwardly facing air-deflecting surface for reducing air resistance to forward movement of the tractor-trailer vehicle, and supporting structure means adapted to be connected to both said air deflector and the roof of the tractor cab for mounting said air deflector thereon;

• wherein the improvement comprises,
• A. said air-deflecting surface of said deflector is (1) symmetrical about a vertical center plane and has a central portion and a pair of lateral wing portions symmetrically located on opposite sides of said central portion, (2) is totally curved and forwardly convex in all its horizontal and vertical cross-sectional planes, and (3) in said central portion has a uniform radius of curvature in all horizontal and vertical cross-sectional planes;
• B. said deflector has a top edge and a base edge;
• C. the center of curvature of said central portion of said air-deflecting surface is located on a plane that is parallel to the plane of said base edge of said deflector and below the same, the perpendicular distance between said planes being the product of (a) the radius of curvature extending from said center of curvature to said base edge and (b) the sine of an angle of about 12 to 16 degrees included between that radius and the lower one of said planes;
• and
• D. the radii of curvature of said wing portions of said air-deflecting surface are smaller at said base edge than said radius of curvature of said central portion and gradually increase until at said top edge the radii of curvature of said wing portions are merged into and become equal to the radius of curvature of said central portion;
• and
• E. said supporting structure means includes first means adapted to be rigidly secured to said air deflector, second means adapted to be rigidly secured to said cab roof, and third means adapted to be interconnected between said first and second means to enable said deflector to be mounted so as to have a height, as measured vertically between two horizontal planes each tangent to a respective one of said top and base edges at the mid-point thereof, that is a function of the ratio of (1) the difference in height between the trailer front wall and the tractor cab roof to (2) the horizontal spacing between the rear of the cab and the front wall of the trailer.

An air deflector assembly suitable for mounting on the roof of a cab of a tractor of a tractor-trailer vehicle and including an air deflector providing a frontwardly facing air-deflecting surface for reducing air resistance to forward movement of the tractor-trailer vehicle, and supporting structure means adapted to be connected to both said air deflector and the roof of the tractor cab for mounting said air deflector thereon;

• wherein the improvement comprises:
• A. said air-deflecting surface of said deflector is totally curved and forwardly convex in all its horizontal and vertical cross-sectional planes and is symmetrical about a vertical center plane and has a central portion and a pair of lateral wing portions symmetrically located on opposite sides of said central portion;
• B. said deflector has a top edge of substantially circular curvature and a base edge of elliptical curvature substantially conforming to the equation ##EQU5## inches, wherein x varies between about 34 and 69 inches;
• C. the base edge curve in the middle region thereof over an arc distance of about 20.degree. on either side of the midpoint of said base edge curve, corresponding to said central portion of said air-deflecting surface, and the top edge curve over substantially its entire extent, each has a radius of curvature of about 74 inches;
• D. said base edge curve in each of the lateral end regions thereof on either side of said middle region, corresponding to said wing portions of said air-deflecting surface, has a radius of curvature of about 20 inches;
• and
• E. said air-deflecting surface is defined by (1) a generation of said middle region of said base edge curve upwardly through an angle of about 34.degree. to said top edge curve, with the center of curvature of the so-generated central portion of said air-deflecting surface being located on a plane that is parallel to the plane of said base edge curve and below the same, the perpendicular distance between said planes being the product of (a) the 74 inch radius of curvature extending from said center of curvature to said base edge curve and (b) the sine of an angle of about 12.degree. to 16.degree. included between that radius and the lower one of said planes, and (2) a generation of said lateral end regions of said base edge curve through said angle of about 34.degree. with gradually increasing radii of curvature until at said top edge the radii of curvature of said wing portions are merged into and become equal to the radius of curvature of said central portion;
• and
• F. said supporting structure means includes first means adapted to be rigidly secured to said air deflector, second means adapted to be rigidly secured to said cab roof, and third means adapted to be interconnected between said first and second means to enable said deflector to be mounted so as to have a height, as measured vertically between two horizontal planes each tangent to a respective one of said top and base edges at the mid-point thereof, that is a function of the ratio of (1) the difference in height between the trailer front wall and the tractor cab roof to (2) the horizontal spacing between the rear of the cab and the front wall of the trailer.