Intelligent valve technology helps improve engine economy

    In the process of optimizing internal combustion engines, the valve opening and closing strategy is one of the few remaining problems. Currently, Camcon, a British company, is developing a technology called Intelligent Valve Actuation, which aims to solve the problem of valve control strategy during engine combustion. Roger Stone, the company's technical director, said that the intelligent valve control technology is committed to meeting the relevant emission standards in 2020.

Intelligent valve control structure: closed on the left, open on the right

    Roger Stone pointed out that the basic strategy of this technology is to eliminate the mechanical connection between the valve and the crankshaft during rotation, so that the valve timing/lift/cycle can be flexibly adapted to the actual speed and load in each cycle, thereby optimizing the engine combustion.

    Intelligent valve control technology is said to overcome the limitations of variable valve control systems by combining high-speed CNC technology and high-precision valve opening and closing during the valve operation process. Engineers said that in fact, this is a valve-by-wire technology.

    “For a long time, designers were constrained by the direct mechanical connection between the crankshaft and the engine,” Stone said. “Now, designers are thinking about the engine at a specific load and speed and developing a valve control strategy based on that, without the constraints of traditional mechanical structures.”

    The most direct effect of optimizing valve lift/timing is the optimization of torque, fuel economy and emissions. In addition, this technology can be combined with homogeneous charge compression ignition (HCCI) technology and is compatible with 2-cylinder and 4-cylinder engines.

Enable advanced combustion strategies

    Camcon’s development work has demonstrated that even a relatively simple modification can provide higher low-speed torque, reduced pumping losses and better exhaust gas recirculation control in existing engines. Based on this, and simulations and bench testing, Stnoe estimates that this technology could improve fuel economy and CO2 emissions by at least 15%.

    It is a very simple change to extend the intake valve opening time to provide enough working time for the Miller cycle. In addition, it can overcome some difficulties in the homogeneous compression ignition process, because during the low engine speed, the crankshaft runs 720 degrees (two weeks) and a lot of valve control can be done. For example, the intake inertia can be reduced by shortening the intake stroke, thus creating the best intake flow at different speeds.

    According to the development trend of the intake automobile industry, the application of cylinder cut-off technology has also been further developed. The intelligent valve control strategy can also ensure that no single cylinder is in a non-working state for a long time by activating each cylinder in turn.

    Due to its fast response characteristics, this strategy is also suitable for two-stroke engines with speeds below 3,000 rpm.

    Stone pointed out that intelligent valve control is a combination of a compact desmodromic valve train and a mechanical regulator from Camcon.

    The system is controlled by a valve control unit (VCU), which is more efficient than the ignition control or injection control in conventional engines. The injection or ignition control unit can only calculate the amount of fuel required for a single cycle of each cylinder, while the valve control unit can monitor the valve position 100 times during each cycle.

Lower fuel consumption

    The core component of intelligent valve control technology is Camcon's mechanical regulator, which is based on the company's Binary Actuation Technology. The multi-mechanical regulator has two stable zero-power states, while traditional solenoids only have one zero-power state. The valve travel is limited to a fixed range, so power is consumed only when switching the cylinder cut-off object.

Continuously controlled rail valve structure of intelligent valve control system

    Stone pointed out that the designers realized a multi-pole layout by using a rotating permanent magnet, just like a compact electric motor with ultra-fast response rate. Converting the rotary motion into high-precision linear valve opening and closing motion is the key to the system, which is equipped with a cam with a continuous control track structure for each valve. The cam of the third cam acts as an energy recovery spring, recovering the energy of a valve operation and using it in the control of the second valve, improving the efficiency of the engine operation.

    According to Camcon, the rotary regulator operates more efficiently, making it compatible with lower voltage 12-volt automotive electrical systems.

    The experimental report shows that by using intelligent valve control technology, the noise of the crankshaft and valves during engine operation is also greatly reduced, especially at low speeds. When the engine is idling, the fuel injection system will become the main source of engine noise.

    Camcon is currently negotiating with several OEMs for cooperation. Once the cooperation is reached, the intelligent valve control system will enter the mass production stage. The company claims that the technology can help engines meet 2020 emission and fuel economy regulations.