Camless piston engine

A camless or free-valve piston engine has poppet valves operated by means of electromagnetic, hydraulic, or pneumatic actuators instead of cams. Actuators can be used to both open and close valves, or to open valves closed by springs or other means.

As a camshaft normally has only one lobe per valve, the valve duration and lift is fixed. The camshaft rotates at half the rate of the crankshaft. Although many modern engines use camshaft phasing, adjusting the lift and valve duration in a working engine is more difficult. Some manufacturers use systems with more than one cam lobe, but this is still a compromise as only a few profiles can be in operation at once. This is not the case with the camless engine, where lift and valve timing can be adjusted freely from valve to valve and from cycle to cycle. It also allows multiple lift events per cycle and, indeed, no events per cycle—switching off the cylinder entirely.

Camless development

Camless engines are not without their problems. Common issues include high fuel consumption, accuracy at high speed, temperature sensitivity, weight and packaging, high noise, high cost, and unsafe operation if there are electrical problems in the vehicle.

Camless valve trains have long been investigated by several companies, including Renault, BMW, Fiat, Valeo, General Motors, Ricardo, Lotus Engineering, Ford, Jiangsu Gongda Power Technologies and Koenigsegg's sister company FreeValve.^{[1][2][3][4][5]} Camless systems are commercially available, although not yet in engines in production road vehicles. In the spring of 2015 Christian von Koenigsegg told reporters that the technology pursued by his company is "getting ready for fruition", but said nothing specific about the time-table.^[6][7]

In November 2016, Chinese automobile manufacturer Qoros Auto displayed a Qoros 3 hatchback at the 2016 Guangzhou Motor Show showcasing a new Qoros ‘Qamfree’ engine. The engine's Swedish designer FreeValve claims that the 1.6-litre turbocharged engine will produce 230 bhp and 320Nm of torque. They also claim that, compared to a similar traditional engine, it offers a 50% reduction in size (including a 50 mm lower height), 30% reduction in weight, 30% improvement in power and torque, 30% improvement in fuel economy, and a 50% reduction in emissions.^[8] Christian Koenigsegg claims in a video that the Qamfree engine with the PHEA camless technology is based on an existing Qoros engine that was "...developed in Germany Austria five six years ago...".^[9]

Christian Koenigsegg also claims that the PHEA camless technology allows the elimination of the pre-catalytic converter, because the standard catalytic converter can be brought up to temperature quickly by manipulating the exhaust cycle.^[9]

Camless engines in marine and power stations

Advantages

Because there is no camshaft, there are fewer moving parts. The cam shaft rollers and push rods have been replaced by an electro-hydraulic actuator system which uses the existing fuel pumps. This reduces development risks of the new system by employing existing technology.^[10] Direction changing on older B&W MC engines was engaged by changing the direction of the cam roller. With the new cam-less engine it is controlled by a computer. This gets rid of mechanical failures that can damage the engine if there is a malfunction in the engine when changing directions. Also, there is no chain connection between the crank shaft and the cam shaft so the engine is lighter with less points of failure. Since there is no camshaft, the parasitic load on the engine output is removed. This is particularly useful in large marine engines that can produce up to 100 megawatts as it can equate to a large amount of power saving. With a cam-less engine, fuel injection and exhaust timing are directly controlled by an Engine control unit and it can be constantly changed and adjusted without stopping the engine. This allows for the engine to run at lower RPM which is useful for maneuvering as it allows slower ship speeds for safe and precise docking. Aditionally, when a ship is maneuvering, the computer controlled Fuel injection and valve timing allows for faster RPM control, hence faster stopping in emergency situations.

Emissions

Camless engines can produce less emissions because they allow for more precise control of the combustion procedure, allowing for more complete combustion of all hydrocarbons. The computer will sense when not all fuel is being consumed and immediately relax valve timings to supply less fuel to the cylinder. Also, the ECU constantly adjusts valve timings, height and fuel/air mixtures to optimize efficiency for a given RPM/torque load. The ECU can also sense when there is a high amount of NOx and SOx (Sulfur oxide) emission and change the timing to make the Exhaust gas hotter or cooler. Since the engine is run electronically and not mechanically, camless engines can be updated to meet new emission regulations without mechanical modifications.

Fuel Injection

Cam-less engines can further reduce NOx emissions with the use of fuel staging. Instead of simply injecting a constant stream of fuel, fuel staging injects the fuel at the optimal time for the most complete combustion. This is paricularly useful for the MAN B&W ME engine because of its long stroke. Fuel injection can shut off when there is sufficient pressure and add more fuel when there is less pressure making the engines closer to a perfect diesel cycle. This allows the engine to run as efficiently as the environment and heat capacity of the metal will allow.

Long Term Effects

Because these new engines can diagnose themselves and run efficiently without an operator changing settings, these engines require less crew to maintain them when at sea. This crew reduction equates to cheaper shipping for companies and hence more and cheaper global trade^[11]..

Camless engines in cars

The Swedish company Freevalve AB (formerly Cargine), a sister company to Koenigsegg Automotive AB, are developing a camless system and have successfully implemented the system on an existing SAAB car engine.^{[12][13][14][15]} In April 2016 the Chinese car manufacturer Qoros presented a concept car incorporating Freevalve technology.^[16]

See also

• Helical camshaft
• Multiair

References

External links

• "EVIC Engine Home Page". David Bowes. 2011-01-20. Retrieved 2011-01-20. 
• "Valeo tests camless system for gas engines; supplier hopes to produce fuel-saving technology by '08". AutoWeek. Retrieved October 14, 2005. 
• "Advanced Actuators Research Group, Department of Mechanical Engineering, University of South Carolina". 
• "Valeo signs up 'several global automakers' for camless engine". 
• "Study of a Pneumatic Hybrid aided by a FPGA Controlled Free Valve Technology System". 
• "ME Engines – the New Generation of Diesel Engines" (PDF).