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Replacing 4-Cycle With 6-Cycle Engine

Wed, 03/13/2013 - 9:08am
Terry Persun, Technology Journalist

In its phase 2 operation, the Kashmerick Engine Systems engine technology is proving its effectiveness and viability for military use, and more.

The K6-Cycle System head was designed on a standard CAD system and then uploaded to Midwest Composite Technologies to their direct metal laser-sintering machine, which produced a production quality component using stainless steel. Technology begets technology when it comes to advancements in many fields. For example, the ability to design and manufacture complex parts without machining, or with minor machining has stepped up the possibilities for alternative fuel engines. Some applications that might benefit from such an engine include military applications where wide multi-fuel capability is desired to reduce critical fuel needs and consumption, as well as commercial utility engines in the 10-40 hp range for lawn cutting machines, welding, pumps, portable generators, washer spraying, and other applications.

The Department of Defense and Kashmerick Engine Systems are working together to develop such an engine that provides a wide and flexible fuel capability so that combustion is insensitive to the fuel used, whether gasoline, alcohols, bio-fuels, oils, or a mixture of these. In addition, the engine in phase-two development could produce lower emissions because continuous combustion occurs inside a separate insulated combustion chamber. And if this isn’t enough, the engine under development is expected to offer improved thermodynamic efficiency and provide less noise, while building on existing technology.

The K6-Cycle System uses the same piston and cylinder assembly for both the gas compressor stroke and for two gas expansion/power strokes. Because there are two power strokes for each three revolutions of the crankshaft, the camshaft must rotate at one-third the crankshaft speed. Basically, a four-cycle system takes air into a piston/cylinder where it compresses the air; then ignites the air and fuel; and finally produces expansion power and exhaust.

The Kashmerick Systems drawings were uploaded to Midwest Composite Technologies for a quick check and then passed to the direct metal laser sintering system for manufacture.

The K6-Cycle System takes in air and compresses the air, but then transfers the air to a separate combustion chamber (also part of the head) where fuel is injected. Half of the expanding gases from this chamber are put back into the original piston/cylinder for expansion power and exhaust. On the third revolution, the other half of the expansion gases from this chamber are put back into the piston/cylinder for expansion power and exhaust. This means that the combustion chamber holds multiple compressed air charges, and its size is variable so that it can be optimized for different engine configurations.

Changes in Manufacturing

According to Jerry Kashmerick, Principal Engineer and Owner of Kashmerick Engine Systems, “The head was made with no tooling, which not only saved money, but time.” Jerry designed the engine using standard CAD tools (see CAD Drawing 1), and then ported the design directly to Midwest Composite Technologies for production. Midwest is a service organization that provides multiple methods for manufacturing components for many different industries. For the Kashmerick Engine components, the company processed them through its DMLS (Direct Metal Laser Sintering) process, where they offer a selection of alloys to provide production quality parts to its customers. “Very little machining was needed because the parts were delivered better than a rough casting we would normally get,” Jerry said.

By going through Midwest Composite Technologies Jerry was able to make a more complicated design than what he could have done using standard machining. “The DMLS technology also allowed me to make minor changes to the design without being concerned about fabrication challenges,” he said. “Plus, Midwest Composite Technologies delivered the component in a few days, which meant that I could make more refinements to the design and still be on schedule.”

The Kashmerick Systems drawings were uploaded to Midwest Composite Technologies for a quick check and then passed to the direct metal laser sintering system for manufacture.Since Midwest uses an additive technology to produce the parts, each part could have a more complex internal structure than usual. Once design restrictions are removed, it’s possible to take minor risks and come up with a stronger, more efficient design in the end, which greatly aided in the Kashmerick Engine design phases.

Kashmerick Systems used a 17-4 PH (or Type 630) precipitation hardened stainless steel material, commonly used in the aerospace industry, for the head, and two different alloys for the combustion chamber, and a 100 percent non-magnetic cobalt chrome alloy for three or more smaller components that required a much higher temperature range for operation. Part sizes range from the head, which is 6-in x 4-in x 2.5-in (Pic-1), and the combustion chamber, which is 2.5-in diameter x 2.75-in long (Pic-2), to smaller parts like the fuel injector insulator (0.24-in diameter x 1.12-in long) (also Pic-2), the cup-shaped combustor (1.5-in diameter x 1-in long) and the finned combustion component (2.25-in diameter x 1.25-in long) (Pic-3). It is also important to note that the DMLS system is often used for producing tooling inserts, prototypes parts, and wide varieties of end products directly from metal.

Midwest Composite Technologies’ DMLS system uses a high-temperature laser to melt and fuse, or sinter, a powdered metal material into a three-dimensional component for end-user productions. Because these machines produce the component in layers of 0.0008-inches (20 microns) thick, the parts created are often production ready. When post-production work is needed, it is usually very minor. DMLS is the ideal solution to produce parts for low volume production needs such as those required by companies like Kashmerick Engine Systems.

The design and testing of new systems is only the beginning. Once the design is proven, there must be a place for it to be used that goes beyond a few applications. For the K6-Cycle System, that includes rural use by farmers that can use alcohol or plant oils as fuel for equipment, irrigation, and electricity; for export to developing countries where fuel quality is variable; for use on an engine powered Home Central Power System that could replace traditional natural gas or propane home heating; for refrigeration units on truck trailers that must operate quietly, efficiently, and with low emissions on diesel fuel; and for all types of Green applications with potential high-efficiency, low emissions, and multi-fuel and organic fuel capability.

Overall, the project is running smoothly and proving to be a viable alternative to present four-cycle engines available, particularly aiming at generating a smaller overall carbon footprint, especially in smaller, low-cost utility engines. Thanks to DMLS technologies and partner companies like Midwest Composite Technologies, further testing can go on smoothly.

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