Words to remember:
Variable displacement – Inwardly changing the working size of an engine. (In our case relates to the length of the stroke of the piston)
Variable compression ratio – Increasing or decreasing the space between the top of the piston and the inside top of the cylinder head. (This is where combustion takes place.)
You asked, here’s our answer
Why it’s Better
Thanks for your interest in the Hefley Tec X1 and X2. This will help your understanding of our project!
By now, most people know if they order a Mustang with a 4.0 it will get better gas mileage than the 5.0 even if both are driven same. For a better understanding we will be reviewing the combustion process in conventional engines then explain how the Tec engines design and combustion process is a substantial improvement.
Normal air is about 21 percent oxygen. Oxygen is required and enhances the combustion process. In normal air for instance you could light your lighter and easily pass your finger through the yellow flame without being burned. The flame is just not that “hot”. If oxygen levels were increased 3 times higher around the lighter, there would be no flame, just an explosion in your face! In an engine the amount of static pressure, oxygen and fuel in the combustion chamber determines the force (power) of each stroke. This is expressed in an explosion by heat and quick expansion of the gases. The heat also assures us that the fuel has combusted completely. The explosion in the combustion chamber drives the piston by pushing against the top of the cylinder head.
The conventional engine always has a fixed length stroke that supplies air (oxygen) into a combustion chamber that is also a fixed size. Let’s say an engine with a compression ratio of 12 to 1 is running at full throttle. It’s getting 12 times the normal atmospheric levels of oxygen. Engines that run at or near full throttle generally run near optimum combustion levels. That’s because they combust at maximum pressure and oxygen levels, take full advantage of the higher compression ratios and use all the anti-knock properties of the fuel. Manufacturers must meet their advertised horsepower, so they are sure to carefully set up the engine to take full advantage of the high compression ratio, antiknock fuel qualities, plus proper turbulence and temperature settings. This meets the high horsepower requirements and often results in the most horsepower for the fuel consumed. But we don’t run a large engine at full throttle for a very long period, at least not in a car. Most of the time automobiles run at around to 25 to 35 percent of full power, so we lose the efficiently established at the full throttle exhibition. That means we burn more fuel per mile.
Now if you set the throttle at half you reduce the amount of air that can enter the combustion chamber, the static pressure in the combustion chamber drops by half (pressure in the combustion chamber prior to ignition) and the oxygen level drops by 50 percent (now only 6 times more than the atmosphere). The combustion chamber is still the same size but has less static pressure in it. But more importantly it has less oxygen to keep the combustion at the most efficient level.
Try setting the throttle at 25 percent of maximum, there is even less efficiency as the above principles are applied. It’s the lower power levels that make large engines least efficient. Automobiles are usually driven well below 50% of available power. It’s easy to understand why it costs so much to drive them. Engine designers using computerized fuel and timing management are now able to cover up some of these inherent shortcomings, the engines run smooth but still waste a lot of fuel! These shortcomings still exist and will always exist as long as we use the old conventional engine design.
If you have a smaller engine and load it up properly you can produce these lower levels of power in a very efficient and economical manner. It’s a real problem for car buyers who want economy and ample power too!
Suppose there were an engine that was small and economical inwardly but could become a large and powerful engine at a moment’s notice. It would deliver economy without having to sacrifice power. The Hefley Tec X1 is exactly that engine. In fact it does more than that! Its unique construction allows it to keep the compression ratio at 12 to 1 as it moves from full power downward to its lower power setting. It’s always running at peak efficiently and getting amazing economy. Remember when a conventional engine is at 50 percent of power the compression ratio effectively drops to 6 to 1 (this lowers the efficiency of combustion and ruins fuel economy). Why? Because the combustion chamber remains fixed but the air (oxygen) has been cut back by the throttle effectively reducing the compression ratio. If the air cannot go in then the air mass is reduced to what now becomes the effective compression ratio. In this case it would be 50% of maximum or 6 to 1.
Because of the unique construction of the Tec X1 it keeps the compression ratio basically the same as it changes it’s power settings (and inward size). The piston simply moves outward toward the cylinder head as the engine becomes smaller. Even in today’s established engine construction this would seem impossible. But we do it with less moving parts than conventional engine. You can look directly at some of our patent documents to see how this is done. Try www.HefleyEngine.com look for the “Hefley Workshop” then proceed to steps 5 and 6. This can also be seen in a 3-D animation at the top of the home page.
Another animation in the center of the home page will show you the action of a conventional piston and cylinder, then below it the action of our piston and cylinder. Ours will change displacement while making adjustments to keep the compression ratio the same by extending the length of the piston allowing it to reduce the size of the combustion chamber as needed to maintain the ideal compression ratio.
The Hefley Tec X2, has all of the features as the X1 but has one very important additional feature. The Tec X2 has variable compression ratio. What does this do? It allows the compression ratio (in the combustion chamber) to be adjusted to the type of fuel desired to be used. Each fuel has a particular compression ratio where it operates the best and produces the most power. For instance, regular gas might work best at 12 to 1; high test gasoline might run well at 14 to 1 while diesel might work best at 22 to 1. Bio-diesel might work better at 24 to 1. These ratios may vary depending on engine design, construction, and other factors.
Since the Tec X2 can easily change its compression ratio within a few seconds, it can be adjusted to use any of the above fuels and even new fuels still under development. As the Tec X2 changes its compression ratio, fuel is simply switched from the current fuel injector to the fuel injector holding the alternative fuel. Yes, the same engine can function with improved efficiency as a gasoline (or E85 ethanol) engine, then quickly be converted to diesel or bio-diesel within seconds and function perfectly in that manner too. There is a simple CAM placed on the variable crankshaft that allows the change in compression ratios. This is demonstrated using 3D animation by clicking at the picture of two gears on the right at the second animation from the top in www.HefleyEngine.com
In summary, when the power is reduced on a conventional engine, the throttle reduces the intake of air thus effectively lowering the compression ratio, which reduces the oxygen and static pressure within the combustion chamber. The resulting combustion is far below optimum! Fuel is wasted.
In the Tec X1 we use variable displacement. Instead of substantially reducing the air flow into the combustion chamber we reduce the entire internal size of the engine by reducing the length of the stroke. This smaller engine can then produce a more efficient combustion by working under a load at all times thus producing a better hotter cleaner power stroke. As we reduce the displacement by shortening the stroke, we cause the piston to move closer to the top of the cylinder, thus maintaining the all important compression ratio. Our compression ratio is not allowed to diminish under lighter loads as it does in conventional engines. This allows us to always produce near optimum combustion that saves fuel all the time.
There is one more important point we should make. Our engines may seem complicated, but it actually has less moving parts and is lighter weight that its conventional counterpart. Construction is relatively simple and easy.
The Tec X2 includes all of the above features, but adds variable compression ratio which allows us to change compression ratios to adjust to all types of available fuels from gasoline to diesel and even bio-diesel. This allows the driver to select the current and available fuel he or she feels best at a particular time. They might consider which fuel gives them maximum miles per gallon or best price or comfort or availability. Whichever they choose, the Hefley Tec X2 will comply at the touch of a button.