Positive air pressure system (PAPS) for camera enclosures in dirty environments
View Patent ↗A positive air pressure system resists debris accumulation on an active surface and comprises a frustum-shaped shroud with a baffle plate therein dividing the shroud into baffles, including a positive pressure chamber and a passive back pressure chamber interconnected through an orifice in the baffle plate. An inlet opening is formed in the shroud and in fluid communication with the proximal baffle and a positive pressure air source and to receive air through the inlet opening from the positive pressure air source and create a high-pressure region, greater than a pressure region in the passive back pressure chamber, and in front of the active surface and to expel air out of the positive pressure chamber and into the passive back pressure chamber through the orifice in the baffle plate.
1. A positive air pressure device configured to resist fouling of an active surface, the device comprising:
a shroud having opposite open ends including a proximal open end configured to be closed when mounted adjacent the active surface, and a distal open end opposite the proximal open end, the shroud having an axis between the opposite open ends;
a baffle plate disposed in the shroud and traversing an interior of the shroud and oriented transverse to the axis of the shroud, and an orifice therein aligned with the opposite open ends;
the baffle plate dividing the shroud into baffles interconnected through the orifice including a proximal baffle between the baffle plate and the proximal open end and a distal baffle between the baffle plate and the distal open end; and
an inlet opening formed in an outer wall of the shroud at a location offset from the baffle plate, the inlet opening in fluid communication with the proximal baffle and configured to be in fluid communication with a positive pressure air source to define a positive pressure chamber in the proximal baffle configured to receive air through the inlet opening from the positive pressure air source and create a high-pressure region, greater than a pressure region in the distal baffle, in front of the active surface and to expel air out of the positive pressure chamber and into the distal baffle through the orifice in the baffle plate,
wherein the positive pressure air source further comprises:
an air intake with an air intake opening and an air discharge coupled to the inlet opening of the shroud;
an air displacement device dividing the air intake into a low-pressure chamber between the air intake opening and the air displacement device, and a high-pressure chamber between the air displacement device and the air discharge; and
the air intake opening being larger than the air displacement device and the air discharge to define a low-speed air intake configured to create a low air pressure in the low-pressure chamber in the air intake and a low-speed air flow into the air intake opening to resist drawing airborne particles into the air intake opening.
2. The device of claim 1 , further comprising:
the shroud comprising a frustum-shaped shell enlarging from the proximal open end to the distal open end with the distal open end being larger than the proximal open end and configured to create a dead-air buffer in the distal baffle to define a passive back pressure chamber in the distal baffle.
3. The device of claim 1 , wherein the air intake comprises hollow, nested, inverted frustums, comprising:
an outer shell with a smaller closed top and a larger open bottom defining the air intake opening of the air intake;
an inner shell disposed in the outer shell and being inverted with respect to the outer shell, and having a larger open top and a smaller open bottom defining the air discharge of the air intake;
an open junction between the closed top of the outer shell and the open top of the inner shell;
an air flow path defined from the large open bottom, up through the outer shell, through the open junction, down through the inner shell, and out the smaller open bottom; and
a fan disposed adjacent the open junction and configured to displace air from the outer shell into the inner shell and along the air flow path.
4. The device of claim 3 , further comprising:
the air intake opening and the air discharge of the air intake being concentric and facing the same direction.
5. The device of claim 1 , further comprising:
the air intake opening of the air intake being elevated above the shroud; and
the air intake opening facing downwardly.
6. The device of claim 1 , further comprising:
an elongated tube carrying the air intake and having an upper inlet coupled to the air discharge of the air intake, and a lower outlet coupled to the inlet opening of the shroud; and
the air intake being located nearer an upper end of the tube, and the shroud being located nearer a lower end of the tube, such that the air intake is elevated above the shroud.
7. The device of claim 1 , further comprising:
the shroud being coupled to an active surface;
the active surface being mounted to a support structure;
the air intake being mounted to the support structure at a position above the shroud and the active surface.
8. The device of claim 1 , further comprising:
a camera having a window defining the active surface; and
the proximal open end of the shroud mounted adjacent to the window of the camera with the aperture of the baffle plate aligned with the window.
9. The device of claim 8 , wherein the proximal baffle is substantially enclosed except for the orifice and the inlet opening; and wherein the proximal open end of the shroud is substantially sealed with respect to the camera.
10. The device of claim 1 , further comprising:
an annular flange circumscribing the proximal open end of the shroud;
a mount configured to carry a camera with a window, and having a hole configured to be aligned with the window; and
the annular flange coupled to the mount with the orifice of the baffle plate aligned with the hole of the mount.
11. A positive air pressure system comprising:
a shroud having opposite open ends including a proximal open end configured to be closed adjacent an active surface, and a distal open end opposite the proximal open end, the shroud having an axis between the opposite open ends;
a baffle plate disposed in the shroud and traversing an interior of the shroud and oriented transverse to the axis of the shroud, and an orifice therein aligned with the opposite open ends;
the baffle plate dividing the shroud into baffles interconnected through the orifice including a proximal baffle between the baffle plate and the proximal open end and a distal baffle between the baffle plate and the distal open end;
the shroud having a frustum-shaped shell enlarging from the proximal open end to the distal open end with the distal open end being larger than the proximal open end configured to create a dead-air buffer in the distal baffle to define a passive back pressure chamber in the distal baffle;
an inlet opening formed in an outer wall of the shroud at a location offset from the baffle plate, the inlet opening in fluid communication with the proximal baffle;
a positive pressure air source having an air intake with an air intake opening and an air discharge coupled to the inlet opening of the shroud, and an air displacement device dividing the air intake into a low-pressure chamber between the air intake opening and the air displacement device, and a high-pressure chamber between the air displacement device and the air discharge, the air intake opening being larger than the air displacement device and the air discharge to define a low-speed air intake configured to create a low air pressure in the low-pressure chamber in the air intake and a low-speed air flow into the air intake opening to resist drawing airborne particles into the air intake opening; and
an airway connecting the positive pressure air source to the inlet opening formed in the shroud.
12. The system of claim 11 , wherein the air intake comprises hollow, nested, inverted frustums, comprising:
an outer shell with a smaller closed top and a larger open bottom defining the air intake opening of the air intake;
an inner shell disposed in the outer shell and being inverted with respect to the outer shell, and having a larger open top and a smaller open bottom defining the air discharge of the air intake;
an open junction between the closed top of the outer shell and the open top of the inner shell;
an air flow path defined from the large open bottom, up through the outer shell, through the open junction, down through the inner shell, and out the smaller open bottom; and
a fan disposed adjacent the open junction and configured to displace air from the outer shell into the inner shell and along the air flow path.
13. The system of claim 11 , further comprising:
the air intake opening of the air intake being elevated above the shroud; and
the air intake opening facing downwardly.
14. The system of claim 11 , wherein the airway further comprises:
an elongated tube carrying the air intake and having an upper inlet coupled to the air discharge of the air intake, and a lower outlet coupled to the inlet opening of the shroud; and
the air intake being located nearer an upper end of the tube, and the shroud being located nearer a lower end of the tube, such that the air intake is elevated above the shroud.
15. The system of claim 11 , further comprising:
the shroud being coupled to an active surface;
the active surface being mounted to a support structure;
the air intake being mounted to the support structure at a position above the shroud and the active surface.
16. The system of claim 11 , further comprising:
an active surface; and
the proximal open end of the shroud mounted adjacent to the active surface with the orifice of the baffle plate aligned with the active surface.
17. The system of claim 16 , wherein the proximal baffle is substantially enclosed except for the orifice and the inlet opening; and wherein the proximal open end of the shroud is substantially sealed with respect to the active surface.
18. The system of claim 11 , further comprising:
an annular flange circumscribing the proximal open end of the shroud;
a mount configured to carry a camera with a window, and having a hole configured to be aligned with the window; and
the annular flange coupled to the mount with the aperture of the baffle plate aligned with the hole.
19. The system of claim 11 , further comprising a hydrophobic coating applied to the active surface.
20. A positive air pressure system, comprising:
an active surface;
a shroud having opposite open ends including a proximal open end closed adjacent the active surface, and a distal open end opposite the proximal open end, the shroud having an axis between the opposite open ends;
a baffle plate disposed in the shroud and traversing an interior of the shroud and oriented transverse to the axis of the shroud, and having an outer perimeter contiguous an interior surface of the shroud, and an orifice therein aligned with the opposite open ends;
the baffle plate dividing the shroud into baffles interconnected through the orifice including a proximal baffle between the baffle plate and the proximal open end and a distal baffle between the baffle plate and the distal open end; and
an inlet opening formed in an outer wall of the shroud at a location offset from the baffle plate, the inlet opening in fluid communication with the proximal baffle;
a positive pressure air source coupled to the shroud and in fluid communication with the inlet opening of the shroud, and configured to introduce air into the proximal baffle through the inlet opening to define a positive pressure chamber in the proximal baffle and create a high-pressure region, greater than a pressure region in the distal baffle, in front of the active surface and to expel air out of the positive pressure chamber and into the distal baffle through the orifice in the baffle plate; and
the positive pressure air source having an air intake with an air intake opening and an air discharge coupled to the inlet opening of the shroud, and an air displacement device dividing the air intake into a low-pressure chamber between the air intake opening and the air displacement device, and a high-pressure chamber between the air displacement device and the air discharge, the air intake opening being larger than the air displacement device and the air discharge to define a low-speed air intake configured to create a low air pressure in the low-pressure chamber in the air intake and a low-speed air flow into the air intake opening to resist drawing airborne particles into the air intake opening.
21. The system of claim 20 , further comprising:
the active surface being mounted to a support structure;
an elongated tube carrying the air intake and having an upper inlet coupled to the air discharge of the air intake, and a lower outlet coupled to the inlet opening of the shroud; and
the air intake being located nearer an upper end of the tube, and the shroud being located nearer a lower end of the tube, such that the air intake is elevated above the shroud.
22. The system of claim 20 , wherein the active surface comprises a hydrophobic coating.