초록 ▼

A variety of embodiments of exhaust systems for engines including small off-road engines, and related methods of operation, are disclosed. In at least some embodiments, the exhaust system includes a first conduit that receives exhaust emissions from a first engine cylinder, and a second conduit that

A variety of embodiments of exhaust systems for engines including small off-road engines, and related methods of operation, are disclosed. In at least some embodiments, the exhaust system includes a first conduit that receives exhaust emissions from a first engine cylinder, and a second conduit that communicates air to a first port on the first conduit. The air mixes with the exhaust emissions within the first conduit so as to produce a chemical reaction, and a level of at least one undesirable component of the exhaust emissions is reduced. Further, the exhaust system does not include any catalytic converter. In some embodiments, the exhaust system further comprises a crankcase ventilation system.

대표청구항 ▼

1. An internal combustion engine comprising: a cylinder;an exhaust conduit coupled to the cylinder and receiving exhaust emissions from the cylinder;a blower housing;a secondary air conduit coupling an inner region within the blower housing to an orifice on the exhaust conduit,wherein the secondary

1. An internal combustion engine comprising: a cylinder;an exhaust conduit coupled to the cylinder and receiving exhaust emissions from the cylinder;a blower housing;a secondary air conduit coupling an inner region within the blower housing to an orifice on the exhaust conduit,wherein the secondary air conduit receives air from the inner region and communicates the air to the orifice, the air being directed through the blower housing by a fan that directs at least some additional air to proceed out the blower housing and around one or more engine components so as to cool the one or more engine components, andwherein the air communicated to the orifice is mixed with the exhaust emissions and, due to an exothermic oxidation reaction, results in a reduction in at least one component of the exhaust emissions;a first valve assembly associated with the secondary air conduit, wherein the first valve assembly at least partially governs a flow of the air through the secondary air conduit to the orifice on the exhaust conduit, wherein the first valve assembly is implemented within the blower housing, wherein the first valve assembly includes a one-way valve that is a reed valve, wherein a reed of the reed valve has a length ranging from about 20 millimeters to about 50 millimeters, wherein the reed has a width ranging from about 10 millimeters to about 20 millimeters, and wherein the reed has a thickness ranging from about 0.05 millimeters to about 0.3 millimeters; anda muffler coupled to the exhaust conduit, wherein the muffler operates at a back pressure ranging from 22.1 to 62 inches of water at the rated power, wherein the muffler has a size selected to achieve a volume ratio, VR, which is a volume of the muffler divided by a cylinder displacement, ranging from about 3 to about 10,wherein the engine does not include any catalytic converter, and wherein the engine is a small off-road engine. 2. The internal combustion engine of claim 1, wherein the air flows through the secondary air conduit at a rate of 60 to 120 liters per minute at a pressure differential of 300 millimeters of water. 3. The internal combustion engine of claim 2, wherein the secondary air conduit has a length of greater than 0 to about 550 millimeters. 4. The internal combustion engine of claim 3, wherein the secondary air conduit has an internal diameter of about 9.5 to about 13 millimeters. 5. The internal combustion engine of claim 4, wherein the back pressure is a function of the volume ratio according to the formula BP=5.7 VR+5 wherein the BP is the back pressure at a related power. 6. The internal combustion engine of claim 5, wherein the engine has a displacement of less than 1 liter. 7. The internal combustion engine of claim 6, further comprising a second valve assembly linked directly with an intake conduit that is coupled to the cylinder such that an additional pressure within the intake conduit is applied to the second valve assembly, and wherein the second valve assembly at least partially governs the flow of the air through the secondary air conduit based upon the additional pressure. 8. The internal combustion engine of claim 7, wherein the second valve assembly is connected to the intake conduit by way of a vacuum line, and wherein the second valve assembly includes a spring-biased actuator and a vacuum chamber. 9. An internal combustion engine comprising: an exhaust conduit coupled to a cylinder and receiving exhaust emissions from the cylinder;a blower housing;a secondary air conduit coupled between a first valve assembly and the exhaust conduit, wherein the first valve assembly includes a one-way valve that is selected from the group consisting of a reed valve, a ball valve, and an umbrella valve,wherein the engine does not include any catalytic converter,wherein the first valve assembly at least partially governs a flow of first air through the secondary air conduit into the exhaust conduit,wherein the first air is received at a positive pressure so as to improve the flow into exhaust conduit,wherein the first air is mixed with the exhaust emissions and, due to an exothermic oxidation reaction, a reduction in at least one component of the exhaust emissions occurs, andwherein the first air is directed through the blower housing by a fan that directs at least some second air to proceed out the blower housing and around one or more engine components so as to cool the one or more engine components; anda muffler coupled to the exhaust conduit, wherein the muffler operates at a back pressure ranging up to 62 inches of water at the rated power, and wherein the muffler has a size selected to achieve a volume ratio, VR, which is a volume of the muffler divided by a cylinder displacement, ranging from about 3 upward. 10. The internal combustion engine of claim 9, wherein the first valve assembly is implemented within the blower housing. 11. The internal combustion engine of claim 10, wherein the one or more engine components include a cylinder, an intake manifold, and a throttle. 12. The internal combustion engine of claim 9, wherein the first air flows through the secondary air conduit at a rate of 60 to 120 liters per minute at a pressure differential of 300 millimeters of water. 13. The internal combustion engine of claim 12, wherein the secondary air conduit has a length of greater than 0 to about 550 millimeters. 14. The internal combustion engine of claim 13, wherein the secondary air conduit has an internal diameter of about 9.5 to about 13 millimeters. 15. The internal combustion engine of claim 14, wherein the back pressure is a function of the volume ratio according to the formula BP=5.7 VR+5 wherein the BP is the back pressure at a related power. 16. The internal combustion engine of claim 15, wherein the engine has a displacement of less than 1 liter. 17. The internal combustion engine of claim 9, further comprising a second valve assembly linked directly with an intake conduit that is coupled to the cylinder such that an additional pressure within the intake conduit is applied to the second valve assembly, and wherein the second valve assembly at least partially governs the flow of the first air through the secondary air conduit based upon the additional pressure. 18. The internal combustion engine of claim 17, wherein the second valve assembly is connected to the intake conduit by way of a vacuum line, and wherein the second valve assembly includes a spring-biased actuator and a vacuum chamber. 19. An internal combustion engine comprising: a cylinder;an exhaust conduit coupled to the cylinder and receiving exhaust emissions from the cylinder;a blower housing;a secondary air conduit coupling an inner region within the blower housing to an orifice on the exhaust conduit,wherein the secondary air conduit receives air from the inner region and communicates the air to the orifice, the air being directed through the blower housing by a fan that directs at least some additional air to proceed out the blower housing and around one or more engine components so as to cool the one or more engine components, andwherein the air communicated to the orifice is mixed with the exhaust emissions and, due to an exothermic oxidation reaction, results in a reduction in at least one component of the exhaust emissions;a first valve assembly associated with the secondary air conduit, wherein the first valve assembly at least partially governs a flow of the air through the secondary air conduit to the orifice on the exhaust conduit, wherein the first valve assembly is implemented within the blower housing, and wherein the first valve assembly includes a one-way valve that is selected from the group consisting of a reed valve, a ball valve, and an umbrella valve; anda muffler coupled to the exhaust conduit, wherein the muffler operates at a back pressure ranging up to 62 inches of water at the rated power, wherein the muffler has a size selected to achieve a volume ratio, VR, which is a volume of the muffler divided by a cylinder displacement, ranging from about 3 upward,wherein the engine does not include any catalytic converter, and wherein the engine is a small off-road engine. 20. The internal combustion engine of claim 19, wherein the one-way valve is the reed valve, and wherein a reed of the reed valve has a thickness ranging from about 0.05 millimeters to about 0.3 millimeters. 21. The internal combustion engine of claim 20, wherein the reed has a length ranging from about 20 millimeters to about 50 millimeters, and wherein the reed has a width ranging from about 10 millimeters to about 20 millimeters. 22. The internal combustion engine of claim 19, further comprising: a second valve assembly linked directly with an intake conduit that is coupled to the cylinder such that an additional pressure within the intake conduit is applied to the second valve assembly, wherein the second valve assembly at least partially governs the flow of the air through the secondary air conduit based upon the additional pressure, and wherein the second valve assembly is connected to the intake conduit by way of a vacuum line, and wherein the second valve assembly includes a spring-biased actuator and a vacuum chamber. 23. The internal combustion engine of claim 9, wherein the one-way valve is the reed valve, and wherein a reed of the reed valve has a thickness ranging from about 0.05 millimeters to about 0.3 millimeters. 24. The internal combustion engine of claim 23, wherein the reed has a length ranging from about 20 millimeters to about 50 millimeters, and wherein the reed has a width ranging from about 10 millimeters to about 20 millimeters. 25. An internal combustion engine comprising: an exhaust conduit coupled to a cylinder and receiving exhaust emissions from the cylinder;a blower housing; anda secondary air conduit coupled between a first valve assembly and the exhaust conduit,wherein the engine does not include any catalytic converter,wherein the first valve assembly at least partially governs a flow of first air through the secondary air conduit into the exhaust conduit,wherein the first air is received at a positive pressure so as to improve the flow into exhaust conduit,wherein the first air is mixed with the exhaust emissions and, due to an exothermic oxidation reaction, a reduction in at least one component of the exhaust emissions occurs, andwherein the first air is directed through the blower housing by a fan that directs at least some second air to proceed out the blower housing and around one or more engine components so as to cool the one or more engine components further comprising a second valve assembly linked directly with an intake conduit that is coupled to the cylinder such that an additional pressure within the intake conduit is applied to the second valve assembly, and wherein the second valve assembly at least partially governs the flow of the first air through the secondary air conduit based upon the additional pressure, and wherein the second valve assembly is connected to the intake conduit by way of a vacuum line, and wherein the second valve assembly includes a spring-biased actuator and a vacuum chamber. 26. The internal combustion engine of claim 25, wherein the first valve assembly is implemented within the blower housing. 27. The internal combustion engine of claim 26, wherein the one or more engine components include a cylinder, an intake manifold, and a throttle. 28. The internal combustion engine of claim 25, wherein the first air flows through the secondary air conduit at a rate of 60 to 120 liters per minute at a pressure differential of 300 millimeters of water. 29. The internal combustion engine of claim 28, wherein the secondary air conduit has a length of greater than 0 to about 550 millimeters. 30. The internal combustion engine of claim 29, wherein the secondary air conduit has an internal diameter of about 9.5 to about 13 millimeters. 31. The internal combustion engine of claim 30, wherein a back pressure at which a muffler of the engine operates is a function of the volume ratio according to the formula BP=5.7 VR+5 wherein the BP is the back pressure at a related power. 32. The internal combustion engine of claim 31, wherein the engine has a displacement of less than 1 liter. 33. The internal combustion engine of claim 25, wherein the first valve assembly includes a reed valve, and wherein a reed of the reed valve has a thickness ranging from about 0.05 millimeters to about 0.3 millimeters. 34. The internal combustion engine of claim 33, wherein the reed has a length ranging from about 20 millimeters to about 50 millimeters, and wherein the reed has a width ranging from about 10 millimeters to about 20 millimeters. 35. An internal combustion engine comprising: an exhaust conduit coupled to a cylinder and configured to receive exhaust emissions from the cylinder;a muffler coupled to the exhaust conduit, wherein the muffler operates at a back pressure ranging up to 62 inches of water at the rated power, and wherein the muffler has a size selected to achieve a volume ratio, VR, which is a volume of the muffler divided by a cylinder displacement, ranging from about 3 upward;a blower housing;a first valve assembly including a one-way valve that is selected from the group consisting of a reed valve, a ball valve, and an umbrella valve;a secondary air conduit coupled between the first valve assembly and the exhaust conduit; anda fan that is configured to direct first air through the blower housing so that the first air is received at a positive pressure in the secondary air conduit so as to improve the flow into the exhaust conduit, wherein the first valve assembly is configured to at least partially govern a flow of the first air through the secondary air conduit into the exhaust conduit, and also configured to direct at least some second air to proceed out the blower housing and around one or more engine components so as to cool the one or more engine components,wherein the internal combustion engine, which does not include any catalytic converter, is configured to operate so that the first air is mixed with the exhaust emissions and, due to an exothermic oxidation reaction, a reduction in at least one component of the exhaust emissions occurs. 36. The internal combustion engine of claim 35, wherein the first valve assembly is implemented within the blower housing. 37. The internal combustion engine of claim 36, wherein the one or more engine components include a cylinder, an intake manifold, and a throttle. 38. The internal combustion engine of claim 35, wherein the first air flows through the secondary air conduit at a rate of 60 to 120 liters per minute at a pressure differential of 300 millimeters of water. 39. The internal combustion engine of claim 38, wherein the secondary air conduit has a length of greater than 0 to about 550 millimeters. 40. The internal combustion engine of claim 39, wherein the secondary air conduit has an internal diameter of about 9.5 to about 13 millimeters. 41. The internal combustion engine of claim 40, wherein the back pressure is a function of the volume ratio according to the formula BP=5.7 VR+5 wherein the BP is the back pressure at a related power. 42. The internal combustion engine of claim 41, wherein the engine has a displacement of less than 1 liter. 43. The internal combustion engine of claim 35, further comprising a second valve assembly linked directly with an intake conduit that is coupled to the cylinder such that an additional pressure within the intake conduit is applied to the second valve assembly, and wherein the second valve assembly at least partially governs the flow of the first air through the secondary air conduit based upon the additional pressure. 44. The internal combustion engine of claim 43, wherein the second valve assembly is connected to the intake conduit by way of a vacuum line, and wherein the second valve assembly includes a spring-biased actuator and a vacuum chamber. 45. The internal combustion engine of claim 35, wherein the one-way valve is the reed valve, and wherein a reed of the reed valve has a thickness ranging from about 0.05 millimeters to about 0.3 millimeters. 46. The internal combustion engine of claim 45, wherein the reed has a length ranging from about 20 millimeters to about 50 millimeters, and wherein the reed has a width ranging from about 10 millimeters to about 20 millimeters. 47. A method of operating an internal combustion engine comprising: providing a secondary air conduit coupled between a first valve assembly and an exhaust conduit, wherein the first valve assembly includes a one-way valve that is selected from the group consisting of a reed valve, a ball valve, and an umbrella valve,directing first air through a blower housing by a fan;directing, by way of the fan, at least some second air to proceed out the blower housing and around one or more engine components so as to cool the one or more engine components;at least partially governing a flow of the first air through the secondary air conduit into the exhaust conduit by way of the first valve assembly, wherein the first air is received in the secondary air conduit at a positive pressure;receiving exhaust emissions from the cylinder at the exhaust conduit;communicating the first air into the exhaust conduit, wherein the flow of the first air into the exhaust conduit is improved due to the receiving of the first air at the positive pressure;mixing the first air with the exhaust emissions at the exhaust conduit so that, due to an exothermic oxidation reaction, a reduction in at least one component of the exhaust emissions occurs, even though the engine does not include any catalytic converter; andreceiving an output from the exhaust conduit at a muffler coupled thereto and operating at a back pressure ranging up to 62 inches of water at the rated power, wherein the muffler has a size selected to achieve a volume ratio, VR, which is a volume of the muffler divided by a cylinder displacement, ranging from about 3 upward. 48. The internal combustion engine of claim 47, wherein the first valve assembly is implemented within the blower housing. 49. The internal combustion engine of claim 48, wherein the one or more engine components include a cylinder, an intake manifold, and a throttle. 50. The internal combustion engine of claim 47, wherein the first air flows through the secondary air conduit at a rate of 60 to 120 liters per minute at a pressure differential of 300 millimeters of water, wherein the secondary air conduit has a length of greater than 0 to about 550 millimeters, and wherein the secondary air conduit has an internal diameter of about 9.5 to about 13 millimeters. 51. The internal combustion engine of claim 50, wherein the back pressure is a function of the volume ratio according to the formula BP=5.7 VR+5 wherein the BP is the back pressure at a related power. 52. The internal combustion engine of claim 51, wherein the engine has a displacement of less than 1 liter. 53. The internal combustion engine of claim 47, further comprising a second valve assembly linked directly with an intake conduit that is coupled to the cylinder such that an additional pressure within the intake conduit is applied to the second valve assembly, and wherein the second valve assembly at least partially governs the flow of the first air through the secondary air conduit based upon the additional pressure. 54. The internal combustion engine of claim 53, wherein the second valve assembly is connected to the intake conduit by way of a vacuum line, and wherein the second valve assembly includes a spring-biased actuator and a vacuum chamber. 55. The internal combustion engine of claim 47, wherein the one way valve is the reed valve, wherein a reed of the reed valve has a thickness ranging from about 0.05 millimeters to about 0.3 millimeters, wherein the reed has a length ranging from about 20 millimeters to about 50 millimeters, and wherein the reed has a width ranging from about 10 millimeters to about 20 millimeters.