Patent Application
20100006076
The present invention relates to a breather system, more specifically, a breather system that ventilates the valve chamber and the cam chamber of an engine while preventing oil and blow-by gas from being emitted into the atmosphere.
During the use of combustion engines, combustion gases, also known as blow-by gases, are created during combustion in the engine cylinder. In overhead cam engines, these blow-by gases may enter into the valve chamber and the cam chamber through leak paths along the valve stems and the rings. This blow-by gas creates excessive pressure within the valve chamber and the cam chamber and may damage oil seals and other components. Therefore, in order to vent these gases from the valve chamber, the cam chamber, and the crankcase, some engines contain breather systems.
Some breather systems produced today utilize hollow crankshafts or hollow camshafts that are connected to the intake system of the engine. Thus, in operation, breather systems allow for blow-by gases to recirculate into the engine's intake system. However, these breather systems remain open when the engine is no longer in operation. Thus, oil may enter and clog the breather system if the user stores the engine in a non-vertical orientation.
According to one embodiment of the present invention, a breather system for an engine comprises a camshaft mounted within a cam chamber, the camshaft having an axial breather passage with an inlet, a radial opening in fluid communication with the inlet of the breather passage, and a valve disposed within the radial opening moveable between an open position and a closed position, wherein the valve is in the closed position when the camshaft is stationary and wherein upon rotation of the camshaft, the valve advances from the closed position to the open position to allow blow-by gas to enter into the breather passage.
According to another embodiment of the present invention, a breather system for an engine comprises an axial breather passage having an inlet and an outlet disposed through a camshaft, the camshaft rotatably positioned within a cam chamber. A generally circular disk is mounted on the camshaft. The disk includes a radial opening in fluid communication with the inlet of the breather passage. A valve is disposed within the radial opening moveable between an open position and a closed position. An oil separation chamber is positioned between the outlet of the breather passage and an intake system in fluid communication with a crankcase of the engine, wherein the valve is in the closed position when the camshaft is stationary and wherein upon rotation of the camshaft, the valve advances from the closed position to the open position to allow gas to enter into the breather passage.
The invention is described with reference to the drawings in which like elements are referred to by like numerals. The relationship and function of the various elements of this invention are better understood by the following description. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. The embodiments described below are by way of example only, and the invention is not limited to the embodiments illustrated in the drawings.
Turning now to the drawings and referring to
The camshaft 22 runs parallel with the intake valve 18 and the exhaust valve 20. The camshaft 22 may be of a generally cylindrical shape and span the entire width of the cam chamber 14. One end of the camshaft 22 is coupled with a cam gear 24. The cam gear 24 is configured to rotate the camshaft 22 when the engine 10 is in use. At least one cam lobe is positioned upon the camshaft 22. Cam lobes 26 and 28 are configured to open the intake valve 18 and the exhaust valve 20, respectively, while the camshaft 22 rotates at half of the speed of the crankshaft. Each cam lobe 26 and 28 include a nose 25. Rocker arms may be provided to work in conjunction with the cam lobes 26 and 28 to open and close the intake valve 18 and exhaust valve 20.
As shown in
As shown in
The breather system 30 includes an oil separation chamber 66. The oil separation chamber 66 is configured to separate any oil particles remaining in the blow-by gases prior to the blow-by gases re-entering the intake system of the engine 10. The separated oil flows from the oil separation chamber 66 to the crankcase of the engine 10, which allows the oil to be recycled throughout use of the engine 10. The oil separation chamber 66 is in communication with the outlet 36 of the breather passage 32 and the breather hose 68. In the embodiments shown in
Referring to
The breather system 30 also includes a valve disposed in the radial opening 38. The valve operates to prevent oil from entering the breather system 30 when the engine 10 is not in operation and is moveable from an open position and a closed position. It is understood that a variety of different valves may be used in combination with the breather system 30. As shown
Referring back to
In operation, as the engine 10 is driven, the camshaft 22 is rotated at a speed which is half of that of the engine's crankshaft by the cam gear 24. Oil mist, which contains blow-by gases, enters the cam chamber 14. When the oil mist reaches the radial opening 38, the oil particles are separated from the blow-by gases by centrifugal forces. Because the centrifugal forces are greater upon the heavier oil particles than the lighter blow-by gases, the oil particles are prevented from entering the radial opening 38, while the blow-by gases enter into the radial opening 38.
As the camshaft 22 rotates, the ball 46 within the ball check valve 42 compresses the spring 44 due to centrifugal force. As a result, the ball 46 moves away from the seat 48 and opens the through-hole 50. Blow-by gases that enter the radial opening 38 then travel through the through-hole 50 and into the inlet 34 of the breather passage 32. The blow-by gases exit the breather passage 32 through the outlet 36 and enter into the oil separation chamber 66. The blow-by gases pass through the wire mesh material 82 within the oil separation chamber 66, and the heavier oil particles contained within the blow-by gases condense upon the wire mesh material 82. The condensed oil droplets fall to the bottom of the oil separation chamber 66. The upward motion of the piston causes the pressure within the crankcase to decrease creating a pressure differential between the oil separation chamber 66 and the crankcase. The check valve 86 moves from the closed position to the open position continuously. While the check valve 86 is in the open position, negative forces from the crankcase act upon the condensed oil particles such that they flow through the control passage 84 and back into the crankcase. The separated, condensed oil particles are therefore preserved for recycled use during operation of the engine 10. The remaining blow-by gases enter into the breather hose 68 and are reintroduced through the intake system of the engine 10.
When the engine 10 is not in use, the centrifugal forces present at the radial opening 38 and the ball valve 42 no longer exist since the camshaft 22 is not rotating. As a result, the spring 44 presses against the ball 46 to reposition it against the seat 48. This action, which seals the through-hole 50, prevents oil from entering the breather passage 32 through the radial opening 38. This sealing of the breather passage 32 is particularly advantageous when used with four-stroke engines for hand-held devices, such as lawn trimmers, which may placed in different positions during storage by the user.
Referring now to
Referring specifically to
Referring now to
In this particular embodiment, as the engine 10 is driven, the camshaft 22 is rotated at a speed which is half of that of the crankshaft of the engine by the cam gear 24. Oil mist, which contains blow-by gas, enters the cam chamber 14. When the oil mist reaches the radial opening 38, the oil particles are separated from the blow-by gases by centrifugal forces. Because the centrifugal forces are greater upon the heavier oil particles than the lighter blow-by gases, the oil particles are prevented from entering the radial opening 38, while the blow-by gases enter into the radial opening 38.
As the camshaft 22 rotates, the centrifugal forces caused by the rotation act upon the decompression weight 56 and force the inner surface 76 of the decompression weight 56 to disengage the inner diameter 72 of the dedicated disk 52 and to rotate against the spring forces generated by the torsion spring 62. As a result, the decompression weight 56 rotates from the closed position to the open position and stresses the torsion spring 62. The rotation of the decompression weight 56 causes the pin 58 and the aperture 60 to rotate. When the decompression weight 56 reaches the open position, the outer circumference extension 70 stops the rotation of the decompression weight 56. The aperture 60 disposed within the pin 58 aligns with the radial opening 38, which places the radial opening 38 in fluid communication with the breather system 30. Blow-by gases that enter the radial opening 38 then travel through the through-hole 50 and into the inlet 34 of the breather passage 32.
The blow-by gases exit the breather passage 32 through the outlet 36 and enter into the oil separation chamber 66. The blow-by gases pass through the wire mesh material 82 within the oil separation chamber 66, and the heavier oil particles contained within the blow-by gases condense upon the wire mesh material 82. The condensed oil droplets fall to the bottom of the oil separation chamber 66. Vacuum forces created by the upward motion of the piston causes the check valve 86 to move from the closed position to the open position continuously. While the check valve 86 is in the open position, vacuum forces act upon the condensed oil particles such that they flow through the control passage 84 and back into the crankcase. The separated, condensed oil particles 66 are therefore preserved for recycled use during operation of the engine 10. The remaining blow-by gases enter into the breather hose 68 and are reintroduced through the intake system of the engine 10.
When the engine 10 is not in use, the centrifugal forces present at the radial opening 38 and the decompressor valve 54 no longer exist since the camshaft 22 is not rotating. The spring forces generated by the torsion spring 62 press against the decompression weight 56 to rotate the decompression weight 56 from the open position to the closed position. As the decompression weight 56 rotates towards the closed position, the pin 58 rotates and the aperture 60 and the radial opening 38 no longer align. The decompression weight 56 engages the inner diameter 72 of the dedicated disk and stops rotating. This action prevents oil from entering the breather passage 32 while the engine is not in operation and stored by the user.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any manner. It can be appreciated that any of the features described herein may be used with any embodiment. The illustrative embodiments are not exclusive of each other or of other embodiments not recited herein. Accordingly, the invention also provides embodiments that comprise combinations of one or more of the illustrative embodiments described above. Modifications and variations of the invention as herein set forth can be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated by the appended claims.
