1. A positive crankcase ventilation (PCV) system comprising:
an oil return line coupled to a PCV oil separator and extending through a crankcase housing; and
a PCV bypass valve positioned in a wall of the oil return line and in fluidic communication with a sealed crankcase chamber, the PCV bypass valve opening when a crankcase chamber pressure exceeds a threshold value and closing when the crankcase chamber pressure falls below another threshold value.
2. The PCV system of claim 1, where the wall of the oil return line is positioned in a cam cover.
3. The PCV system of claim 1, where the wall of the oil return line is positioned in a cylinder head.
4. The PCV system of claim 1, where the wall of the oil return line is positioned in a cylinder block.
5. The PCV system of claim 1, where the wall of the oil return line is positioned in a crankshaft girdle coupled to a cylinder block.
6. The PCV system of claim 1, where the PCV bypass valve is positioned below a cylinder.
7. The PCV system of claim 1, where the PCV bypass valve is positioned vertically above a crankshaft.
8. The PCV system of claim 1, where the PCV bypass valve is positioned between two piston rods.
9. The PCV system of claim 1, where the PCV bypass valve is in fluidic communication with an intake conduit.
10. The PCV system of claim 1, where the threshold values are equivalent.
11. The PCV system of claim 10, where the threshold values are pre-set.
12. The PCV system of claim 1, where the PCV bypass valve is a flapper valve.
13. The PCV system of claim 1, where the PCV bypass valve is removably coupled to the wall.
14. A method for operating a positive crankcase ventilation (PCV) system, comprising:
circulating gas through a sealed crankcase chamber in fluidic communication with a higher and lower pressure intake volume in an intake system; and
when a crankcase chamber pressure exceeds a threshold value, opening a PCV bypass valve in the PCV system, the PCV bypass valve positioned in a wall of an oil return line coupled to an oil separator, the PCV bypass valve in fluidic communication with the sealed crankcase chamber and the lower pressure intake volume.
15. The method of claim 14, where the higher pressure intake volume is positioned upstream of a throttle and the lower pressure intake volume is positioned downstream of the throttle.
16. The method of claim 14, further comprising flowing gas through the oil return line, an oil separator, and to the lower pressure intake volume.
17. The method of claim 14, further comprising closing the PCV bypass valve when the crankcase chamber pressure falls below a threshold value.
18. A positive crankcase ventilation (PCV) system comprising:
an oil return line opening into an oil reservoir, extending through a crankcase housing, and coupled to an oil separator; and
a PCV bypass valve positioned in a wall of the oil return line and in fluidic communication with an intake conduit and a sealed crankcase chamber, the PCV bypass valve opening when a pressure in the crankcase chamber exceeds a threshold value, the wall of the oil return line positioned in a crankshaft girdle coupled to a cylinder block.
19. The PCV system of claim 18, where the PCV bypass valve is a flapper valve.
20. The PCV system of claim 18, where the intake conduit is downstream of a throttle.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A blower attachment for a lawnmower comprising:
an impeller attachable to the lawnmower, the impeller including a plurality of blades, the impeller defining an outer impeller diameter; and
a shroud attachable to the lawnmower, the shroud having a bottom portion below the impeller defining an airflow inlet, the airflow inlet having a diameter less than the outer impeller diameter, wherein air is drawn through the airflow inlet in response to rotation of the impeller for discharge from the lawnmower.
2. The blower attachment of claim 1 wherein the shroud includes a discharge chute.
3. The blower attachment of claim 2 wherein the discharge chute extends generally tangentially from the impeller.
4. The blower attachment of claim 1 wherein the bottom portion of the shroud is disk shaped and wherein the airflow inlet is circular.
5. The blower attachment of claim 4 wherein the bottom portion includes an outer diameter that is greater than twice the airflow inlet diameter.
6. The blower attachment of claim 4 wherein the bottom portion includes an outer diameter that is approximately three times the airflow inlet diameter.
7. The blower attachment of claim 1 wherein the shroud is attachable to the lawnmower housing along a lower periphery of the lawnmower housing.
8. A blower assembly for blowing yard debris comprising:
a lawnmower having a lawnmower housing and a blade attachment portion; and
a blower attachment including:
an impeller removably coupled to the blade attachment portion,
a shroud removably coupled to the lawnmower housing, wherein the shroud includes a planar bottom portion defining a reduced-diameter opening that underlies a portion of the impeller, wherein air drawn is drawn through the reduced-diameter opening in response to rotation of the impeller for discharge from the blower attachment.
9. The blower assembly of claim 8 wherein the blower attachment includes a discharge chute extending generally tangentially from the impeller.
10. The blower assembly of claim 8 wherein the planar bottom portion is disk shaped and wherein the reduced-diameter opening is circular.
11. The blower assembly of claim 10 wherein the diameter of the planar bottom portion is greater than twice the diameter of the reduced-diameter opening.
12. The blower assembly of claim 10 wherein the diameter of the planar bottom portion is greater than three times the diameter of the reduced-diameter opening.
13. The blower assembly of claim 8 wherein the shroud is attachable to the lawnmower housing along a lower periphery of the lawnmower housing.
14. A ducted impeller system for blowing debris, the ducted impeller system being adaptable for mounting to a lawnmower cutting deck, comprising:
an underbody shroud attachable to the lawnmower housing, the underbody shroud including a disc-shaped bottom portion defining an airflow inlet through a central portion thereof, the underbody shroud further including a discharge chute; and
an impeller centrally positioned over the airflow inlet, wherein the underbody shroud and the lawnmower housing cooperate to form an impeller chamber, and wherein air is drawn into the impeller housing through the airflow inlet and discharged from the impeller housing through the discharge chute with rotation of the impeller to blow debris from a lawn surface.
15. The ducted impeller system of claim 14 further including at least one of a grate or a screen seated over the airflow inlet.
16. The ducted impeller system of claim 14 wherein the airflow inlet is circular and defines an airflow inlet diameter.
17. The ducted impeller system of claim 16 wherein the airflow inlet diameter is less than the outer diameter of the impeller.
18. The ducted impeller system of claim 16 wherein the airflow inlet diameter is less than one half of the outer diameter of the impeller.
19. The ducted impeller system of claim 16 wherein the airflow inlet diameter is less than one third of the outer diameter of the impeller.
20. The ducted impeller system of claim 14 wherein the underbody shroud is attachable to the lawnmower housing along a lower periphery of the lawnmower housing.