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techtalk:ref:engmech04a [2019/08/05 01:30] hippysmack [Dissecting the Hayden KVP38 Crankcase Breather Valve] |
techtalk:ref:engmech04a [2024/01/14 21:47] hippysmack |
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The segments of the "Background" information in the patent material are shown in italics below. \\ | The segments of the "Background" information in the patent material are shown in italics below. \\ | ||
- | Comments on this information is shown in bold below. ((Hippysmack of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=39)) \\ | + | Comments on this information is shown in bold below. ((Hippysmack of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-bottom-end/197307-sportster-crankcase-pressure-engine-breathing-wetsumping-and-mods/page39?t=2073932&page=39)) \\ |
- | //A crankcase breather valve for ventilation and pressure control within the crankcase of an internal combustion engine in which pistons stroke upwardly and downwardly in a synchronous movement. The valve is inserted into a breather hose which conducts gases into and out of the crankcase. The valve comprises a resilient valve member, preferably an elastomeric umbrella-type seal, spaced above a seal seat and forming a gap there between through which gases may flow either direction during portions of the pistons' stroke cycle. The valve construction permits three operating modes: firstly to permit the egress of positive pressure gas out of the crankcase and through the gap while the pistons stroke downwardly; secondly, to permit the ingress of a small amount of gas back through the gap into the crankcase when the crankcase pressure changes from positive to negative; and thirdly to check further ingress of gas into the crankcase at greater crankcase suctions, developed when the piston's are moving upwardly.// | + | {{:techtalk:ref:engmech:hayden_breather_valve_drawing_by_hippysmack.jpg?direct&300|}} ((drawing by Hippysmack)) |
+ | //A crankcase breather valve for ventilation and pressure control within the crankcase of an internal combustion engine in which pistons stroke upwardly and downwardly in a synchronous movement. The valve is inserted into a breather hose which conducts gases into and out of the crankcase. The valve comprises a resilient valve member, preferably an elastomeric umbrella-type seal, spaced above a seal seat and forming a gap there between through which gases may flow either direction during portions of the pistons' stroke cycle. The valve construction permits three operating modes: firstly to permit the egress of positive pressure gas out of the crankcase and through the gap while the pistons stroke downwardly; secondly, to permit the ingress of a small amount of gas back through the gap into the crankcase when the crankcase pressure changes from positive to negative; and thirdly to check further ingress of gas into the crankcase at greater crankcase suctions, developed when the piston's are moving upwardly.// | ||
**The breather valve has 3 functions**. \\ | **The breather valve has 3 functions**. \\ | ||
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**The gear driven breather's last year was 1978. \\ | **The gear driven breather's last year was 1978. \\ | ||
- | They left out the '79 style internal reed valve. \\ | + | They left out the '79 style internal reed valve and the fact that Sportsters lost the timed breather in '77. \\ |
- | They are representing ironhead technology up to 1992. \\ | + | They are representing ironhead technology up to 1992 (not true for Sportsters). \\ |
They also cite excessive suction in the oil tank and lack of an oil head at the scavenge port in the sump as being sensitive to crankcase pressure. \\ | They also cite excessive suction in the oil tank and lack of an oil head at the scavenge port in the sump as being sensitive to crankcase pressure. \\ | ||
Some points of interest:** \\ | Some points of interest:** \\ | ||
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* **Vacuum in the air above is pulled from above, not below and the oil in the tank is much heavier than the air above.** \\ | * **Vacuum in the air above is pulled from above, not below and the oil in the tank is much heavier than the air above.** \\ | ||
* **Crankcase pressure cannot suck oil from the tank unless it's already been compromised by other means. \\ (worn or defective OEM breather valve)** | * **Crankcase pressure cannot suck oil from the tank unless it's already been compromised by other means. \\ (worn or defective OEM breather valve)** | ||
- | * **The patent is suggesting that too much vacuum (negative pressure) can cavitate the oil pump.** | + | * **The patent is suggesting that too much vacuum (negative pressure) can cavitate the oil pump.** \\ This is true. |
- | * **It also says the OEM umbrella is normally closed. But it isn't sealed and we do know they do let air back into the crankcase.** | + | * **It also says the OEM umbrella is normally closed**. \\ But it isn't sealed all the time (transients) and we do know they do let a slight amount of air back into the crankcase. \\ This helps to equalize mean pressure somewhat. |
* **According to the patent information, the drain hole in the breather valve system has a dual purpose.** | * **According to the patent information, the drain hole in the breather valve system has a dual purpose.** | ||
- **It drains oil that gets past the umbrella.** | - **It drains oil that gets past the umbrella.** |