Zhou Engine vs. a conventional four-stroke engine
(Updated on June.14, 2020)
Zhou Engine is an invention, which patent number is PCT/CA2014/050106. Its patent file is in (https://patentscope.wipo.int/search/docservicepdf_pct/id00000030299621/APBDY/WO2015120530.pdf ). It is a piston engine. It can work as an internal combustion engine also a combustor. It has very high thermal efficiency and power density.
§1. The principle
Comparing with a conventional four-stroke engine, Zhou Engine uses power-cam mechanism to drive pistons rather than crank-link mechanism. We can realize any piston motion by adjusting the tracks of the power-cam in design. Comparing with a conventional cam mechanism, the power-cam mechanism uses toothed-rollers (seeing the Detail H of fig.3) to avoid almost all the sliding friction, and thus has very high mechanical efficiency. We can realize the piston motion of fig.1, by using of the power-cam of fig.2. Fig.3 shows the radial type of Zhou Engine. The video (or in China https://v.youku.com/v_show/id_XMTUyMTQ4MTQ4OA==.html?from=s1.8-1-1.2) shows the thermodynamic working cycle of the single piston of the Zhou Engine, and toothed-roller’s motion. (This cycle has many differences with the Atkinson cycle, shown in the following.)
Comparing with a conventional four-stroke engine, Zhou Engine has many exclusive characteristics. Its thermodynamic working cycle goes through — intake stroke, compression stroke, combustion period, expansion stroke, and exhaust stroke. It has combustion period and extra expansion exclusively in its piston motion curve, shown in fig.1. It has toothed-rollers, to avoid most of the friction between the piston and the cylinder wall, and to raise the mechanical efficiency of the power-cam greatly, seeing fig.3, or for more detail, please see “Power-cam mechanism” (https://www.dhirubhai.net/pulse/power-cam-mechanism-jing-yuan-zhou ). Its whole flow of intake and exhaust can have no pulsation, to realize the best matching with a turbocharger or a gas turbine, seeing “Turbocharged Zhou Engine”, which ideal thermal efficiency exceeds 0.74.
For manufacturing a Zhou Engine, please select the "Barrel Type of Zhou Engine", or see the fig.9 in the patent file, which volume is far smaller.
§2. Thermal Efficiency
§2-1. The first
This Zhou Engine (say “this invention” or "this engine" in the following), the volume of its expansion stroke is greater than the volume of its intake stroke. To verify this, you can measure it on the screen of the video with a ruler or see fig.1. For example, we say the intake volume is 70 cc, and the expansion volume is 100 cc.
Comparing with a 100 cc conventional four-stroke engine in one thermodynamic cycle, this invention does less work than the 100 cc conventional four-stroke engine. However, the fuel consumption of this invention is equal to a 70 cc conventional four-stroke engine.
Comparing with a 70 cc conventional four-stroke engine in one thermodynamic cycle, this invention does more work than a 70 cc conventional four-stroke engine, at the same fuel consumption, because of the extra expansion. This increases the thermal efficiency. Fig.4 shows ideal PV-diagram of an Otto engine and this invention, and shows the more work clearly.
The Otto engine, its PV-diagram shows in the parts of red lines in fig.4. The process 0-1 is the intake stroke. The process 1-2 is the compression stroke. The process 2-3 is the combustion, complete in a very short instant, and the length of 2-3 indicates the energy comes from the combustion. The process 3-4 is the expansion stroke. The process 4-1-0 is the exhaust stroke. The area 1-2-3-4-1 is the work of the Otto engine in one thermodynamic cycle. Note, the pressure of point 4, is larger than atmospheric pressure; if it expands more and drives the piston, we will obtain more work.
This invention, its PV-diagram shows in the parts of red lines and blue lines in fig.1. The process 7-0-1 is the intake stroke. The process 1-2 is the compression stroke. The process 2-3 is the combustion, complete within the combustion period, and the length of 2-3 indicates the energy comes from the combustion. The process 3-4-5 is the expansion stroke. The process 5-6-1-0-7 is the exhaust stroke. The area 1-2-3-4-5-6-1 is the work of this invention in one thermodynamic cycle. Note, the area 1-4-5-6-1 is the increased work compared to mentioned above.
§2-2. The second
In fig.3, the Zhou Engine uses toothed-rollers to support the component force perpendicular to the piston motion, which comes from the power-cam. The using of toothed-rollers avoids most of the friction that is between piston and cylinder of a conventional four-stroke engine. The friction consumes large power, which is about 20% of the output power of a conventional engine. Therefore, Zhou Engine using the toothed-rollers can increase the thermal efficiency significantly. For more about the toothed-roller, please see “Power-cam mechanism” (https://www.dhirubhai.net/pulse/power-cam-mechanism-jing-yuan-zhou?trk=pulse_spock-articles).
§2-3. The third
About the combustion period and combustion time in fig.6 and fig.7. We reserve combustion period in the piston motion curve of this invention, easier to realize the combustion completed before the expansion stroke. Because the combustion process is earlier than the expansion stroke, the thermal efficiency is high.
§2-4. The fourth
The volume at the end of the exhaust stroke is the clearance volume; the volume at the end of compression stroke is the combustion chamber volume. In this engine, reference fig.1, the clearance volume is near to zero, and is different from the combustion chamber volume. The combustion chamber volume is the volume to actualize the compression ratio and combustion. However, in a conventional engine, the clearance volume is always the same as the combustion chamber volume and cannot be smaller. Theoretically, having a smaller clearance volume is better for increasing the thermal efficiency, and this engine accomplishes that.
§3. Power Density
To increase the power density of an engine, we usually try to increase its speed of revolution, or its frequency of thermodynamic cycles. However, there are two limits limit the frequency of thermodynamic cycles of a conventional four-stroke engine.
§3-1. The first limit
The first limit is the piston speed limit. Because of the crank-link mechanism (reference fig.5), the force Fr that come from link-rod is resolved into Fw and Fg, the Fw is the force that is perpendicular to piston motion and act on the cylinder wall. The Fw causes to a huge friction force on the cylinder wall. According to our experience, any pair of friction has an allowable value of pressure×velocity, if overrun the allowable value, the pair of friction will burn up. Therefore, the Fw limits the piston speed, and then limits the frequency of thermodynamic cycles.
§3-2. The second limit
The second limit is combustion time. The combustion process takes a period of time, this is natural, the period is the combustion time. Fig. 6 shows the relation of piston motion to combustion time of a conventional four-stroke engine. While revolving in normal frequency (shown in (a)), the combustion time is around the top dead center, the engine is in high thermal efficiency. While revolving in high frequency (shown in (b)), the period of thermodynamic cycle is shorter, the combustion time covers most of expansion stroke, the thermal efficiency is lower naturally; if further increase the frequency, we cannot obtain more power, only use up more fuel. Therefore, the combustion time limits the frequency of thermodynamic cycles and power density.
This invention breaks through the above two limits:
§3-3. Break through the first limit
The piston of this invention does not have the Fw above, correspondingly, the force that is perpendicular to piston motion and come from the power-cam, acts on the toothed-rollers (seeing fig. 3), and not on the cylinder wall. The using of the toothed-rollers avoids most of the sliding friction, which is between piston and cylinder wall of a conventional engine. So the piston speed of this invention does not have the first limit mentioned above.
§3-4. Break through the second limit
This invention reserves combustion period to realize the revolving in high frequency of thermodynamic cycles. Fig.7 shows the relation of piston motion to the combustion time of this invention. While revolving in normal (or lower) frequency, the combustion time within the combustion period, the engine is in high thermal efficiency, shown in (a). While revolving in high frequency, the combustion time is near the combustion period, the engine is still in high thermal efficiency, shown in (b), if we further increase the frequency, we can obtain more power. Additionally, if we want a higher frequency of thermodynamic cycles, we can reserve longer combustion period in the piston motion curve in design. Please compare fig.6 with fig.7. Thus, this invention breaks through the second limit mentioned above.
For the better performance of Zhou Engine, please read “Turbocharged Zhou Engine” (https://www.dhirubhai.net/pulse/turbocharged-zhou-engine-jing-yuan-zhou ).
For more information on this invention, please see the article “About Zhou Engine” (https://www.dhirubhai.net/pulse/zhou-engine-jing-yuan-zhou?trk=pulse_spock-articles ) and which links.
For more discussion of the prototype of this invention, please see “An Outline Design of Zhou Engine & Its Comparisons” and which links.
For more on high power density of Zhou Engine, please see "A Primary Design Example of Turbocharged Zhou Engine Vs. Wartsila 12V32"(https://www.dhirubhai.net/pulse/primary-design-example-turbocharged-zhou-engine-vs-wartsila-zhou?published=t ) and which links.
发明“周引擎”，我正寻求合作伙伴和资金支持。
7 年Hi Greg Cotton, Your comments are very interesting. Thank you. After having thought carefully, I will answer you. The optimized design of Zhou Engine is "Turbocharged Zhou Engine" (https://lnkd.in/eh4HGaY ). That has very high thermal efficiency and power density. Generally, I recommend readers to use “Barrel Type of Zhou Engine” (https://www.dhirubhai.net/pulse/barrel-type-zhou-engine-jing-yuan-zhou ). This “radial type of Zhou Engine” is easy to explain its principle.
Director of Engineering at Texas Aircraft Design LLC
7 年Works whether cam track and head turn or cylinder block turns.
Director of Engineering at Texas Aircraft Design LLC
7 年This engine brings back memories of a design I tried (and failed) to patent in 1987. I thought of it as a 5 cycle engine (intake, compression, combustion, expansion, and exhaust). I had not considered your toothed roller and see it may be very advantageous. I offer the following comments: 1) Your design pauses the piston for combustion and allows more complete fuel burn - however pressures and temperatures will be higher. There will be trade offs between thermodynamic efficiency and weight/cost required for endurance. 2) Allowing more complete combustion before expansion means higher piston force over longer time (more power from same displacement and fuel quantity). 3) Combustion requires a finite time. The "pause" can only be optimum for a single engine speed. 4) Exhaust occurs at a higher relatively pressure than Intake and can therefore per performed faster - make sure to allow Intake to complete before closing valve. 2) If you reverse your piston arrangement so the cam track runs outside the pistons (see sketch), the pistons can share a common head. By making this head circular, it can rotate with the cam track to port intake and exhaust to each piston in turn (similar to a rotary valve head). Eliminating valves reduces cost and allows higher RPM and temps. This head can be relatively small and thus more economical to make from exotic material such as ceramic.
一体压铸工艺总监
7 年Hi, MCE-5 company's prototype engines have ventricle move pistons and balance rollers. It's very difficult to reduce the noisy and to much more parts than normal engines make the cost too high than acceptable.
Boss of HSE at LGE CO
8 年I think when in your detail surfaces are frictions than normal engines with oil bearing and crank shaft .then amortisement in this idea is rather than normal engine and the number of parts in this rather than normal.Rotary clobber has amortisement and high voice .Repairing of this engine has difficult and with better money.ok?