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New patent?


marty f said:
anybody understand this and the application?
(edited for clarity as requested)

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=16&f=G&l=50&co1=AND&d=PTXT&s1=yamaha&OS=yamaha&RS=yamaha
Click to expand...

I will give it a shot. The six strokes are: (where d=down u=up)

1. (d) Intake
2. (u) Compression with ignition
3. (d) Expansion with combustion
4. (u) Exhaust
5. (d) Expansion without combustion
6. (u) Compression without Ignition

The purpose of the extra cycle is to cool the cylinder. If you read the typically vague-yet-specific patent it states that there is an overlap between the intake and exhaust valves (both are open) between the exhaust stroke (4) and the intake stroke (1). Note that this period includes the new cycle of expansion without combustion (5) and compression without ignition (6) so during the 5,6 cycle. Basically right at or about TDC of stroke 4, there is an overlap between the intake and exhaust for a short period of time which is driven by a second, smaller lobe on the intake cam. This allows the engine to pull a minimal amount of new, fresh air into the cylinder and it leverages the next two strokes (5 and 6) to wash down the cylinder with cool(er) air. By having a minimal overlap any air that enters the exhaust will only be off by a bit (O2 content) from the sensors perspective which can be overcome with programming. If the overlap was longer the ratio of fresh air to exhaust gases would be high and it would be hard to program out of the O2 sensor reading.

Interesting thought: (if I am right in reading this). The new cycle may be much more efficient if it is designed with a forced induction system adding a bit of intake pressure. This would put pressurized air in the cylinder making the cooling cycle more effective. The problem would be that too much additional air pressure could have significant impact on the O2 (AFR) readings. IOW it may be harder to increase boost pressure beyond the initial design parameters (as you would have to program out the additional O2 impact on AFR.

Besides cooling benefits, this design would natively avoid pre-ignition problems. It would also be interesting to run a small blast of NOS during the valve overlap period to further increase the cooling cycle.
​
It would be cool to see this design with electrically activated valves so you could mess with the overlap position and timing.

There are four variations of the embodiment (idea) that move the valve opening overlap from being between 4-1 to being between 6-1 and another variant does the trick twice, basically combining the periods between 4-5 and 6-1 into two valve overlap periods.
 
Last edited:
DGZRT said:
https://en.wikipedia.org/wiki/Six-stroke_engine

Tons of different Patents. It all sounds good but must not be that easy if the basic tech has been out for 100 years !
Click to expand...

The basic tech has been around but the work continues as there have been many 'takes' on the theory. The Yamaha solution sounds like an incremental improvement on existing work so maybe its something they are looking at or something they are just keeping in their back pocket, lots of companies ( I have a few patents myself) write patents purely as a defensive play in case someone sues them in the future.
 
earthling said:
I will give it a shot. The six strokes are:

1. (d) Intake
2. (u) Compression with ignition
3. (d) Expansion with combustion
4. (u) Exhaust
5. (d) Expansion without combustion
6. (u) Compression without Ignition

The purpose of the extra cycle is to cool the cylinder. If you read the typically vague-yet-specific patent it states that there is an overlap between the intake and exhaust valves (both are open) between the exhaust stroke and the intake stroke (between 4 and 1). Note that this period includes the new cycle of expansion without combustion and compression without ignition so the cycles continue (4,5,6,1). Basically right at or about TDC of stroke 4, there is an overlap between the intake and exhaust for a short period of time which is driven by a second, smaller lobe on the intake cam. This allows the engine to pull a minimal amount of new, fresh air into the cylinder and it leverages the next two strokes (5 and 6) to wash down the cylinder with cool air. By having a minimal overlap any air that enters the exhaust will only be off by a bit (O2 content) from the sensors perspective which can be overcome with programming. If the ratio of fresh air to exhaust gases was high it would be hard to program out of the O2 sensor reading.

Interesting thought: (if I am right in reading this). The new cycle may be much more efficient if there is a forced induction system. This would put pressurized air in the cylinder making the cooling cycle more effective. (EDIT) a second byproduct is that any change in air pressure could have significant impact on the O2 (AFR) readings. IOW it may be harder to increase boost pressure.. maybe. It would be cool to see this design with electrically activated valves so you could mess with the overlap position and timing.

There are four variations of the embodiment (idea) that move the overlap from 4-1 to 6-1 and another variant does the trick twice, basically combining the periods between 4-5 and 6-1.
Click to expand...
Hi earthling, that is what I was thinking also. This design with boost would be especially interesting. Boost levels would likely be even higher than a normal engine due to the cooling cycle.
 
Copyright 2018 @earthling :beer: Two things occur to me (because we are talking about patents, not reality).

1. Why not have a separate (second) exhaust valve with a separate exhaust path that merged with the main path *after the wideband sensor. This would allow for washdown
(cooling cycle) gas exchange to occur without interfering with AFR sensing.

2. Move to electrically controlled valves so you could run variable pressure at the intake (which I said earlier) but this also allows for optimization of the cooling cycle either with or without the separate exhaust valve. This would allow you to separate engine load from efficiency, basically allowing you to control the duty cycle of cooling (valve opening overlap) relative to engine load. This further allows you to control combustion pressure as you may want to use chamber heat to drive a further expansion cycle (giving up cooling) in the name of a small amount of efficiency gain when you are not concerned with cylinder temperatures. When you are concerned with cylinder temperatures you can run a longer duty cycle in exchange for some loss of mechanical efficiency.

Gotta love paper inventions.
 
I know I'm getting a little off topic here, but I would love to see electric over pneumatic valves on snowmobile engines. Camshaft elimination, and then engines could be reversed also to eliminate gears in chaincase. Would be awesome. Lots of weight savings.
 
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