Tula cylinder deactivation technology significantly improves engine efficiency

    Have you ever driven a car with only one cylinder running, or seven cylinders working? Those who have experienced it will be very interested in engines with only an odd number of cylinders running. A technological innovation from 2008 called Tula technology has brought a new engine to the 5.3-liter GMC Yukon model. This engine uses cylinder deactivation technology, which allows the number of cylinders actually working to be adjusted during the operation of the engine. The engine is equipped with a patented controller to help close and open each individual cylinder in time; every 90 degrees of rotation of the engine crank, the controller determines which cylinders' fuel mixture needs to be ignited to meet the driver's power torque requirements while avoiding uncomfortable power system and body vibrations; the controller also controls the time interval between two ignitions in the same cylinder, with the aim of effectively preventing a large drop in cylinder temperature. The basic principle of engine cylinder deactivation technology sounds relatively simple, but without the recent improvement in processing technology, this idea is still difficult to transform into a practical product.

    The Tula engine has an average of 2.4 cylinders in operation in EPA city conditions and 2.5 to 4 cylinders in highway conditions, which is 15 to 18 percent more efficient than a conventional full-time eight-cylinder engine. Cylinder deactivation significantly reduces pumping losses because the throttle opening is increased when a few cylinders are in operation, and the inactive cylinders act as air springs. Even more impressive is the cost of developing and manufacturing the system, because the hardware is already so mature and available that it costs far less to develop a diesel-electric hybrid.

    Those who have driven a car equipped with cylinder deactivation technology and seen the cylinder-by-cylinder operating state map will be shocked by the smooth transition between cylinders in most operating conditions. The whole system does not work when the transmission is in first gear and the engine speed is below 900 rpm, because there is no oil pressure to drive the system under these conditions; above 3800 rpm, the throttle is already wide open, making it difficult to save fuel, so the cylinder deactivation system will not work.

    When the vehicle is stable70 milesWhen driving at a speed of 100 km/h, 5 to 6 cylinders are often required to work at the same time, so the engine can choose to adjust the operation mode of 4 to 8 cylinders; when the speed is only30 miles/hours, all cylinders of the engine will occasionally stop working at the same time, affecting the smoothness of the power system operation. 

    The traditional seat-type engine bracket is retained, and the torque converter and transmission are protected by patents. The Tula controller has no right to modify them, so the practice of increasing torque converter slip and forcing the transmission to downshift to reduce body vibration and further save fuel is not allowed, resulting in the Tula engine not taking any improvement measures for intake resonance and noise elimination, which has also attracted a lot of complaints from test drivers. In addition, the Tula engine has another interesting feature: when the vehicle is coasting, all cylinders of the engine stop working, so engine braking cannot be achieved.

    After applying Tula technology, the eight-cylinder engine has the most obvious fuel savings. The simulation results show1.8LFour-cylinder engines are 8% to 10% more efficient, while six-cylinder engines are up to 15%. The experimental four-cylinder engine uses turbocharged direct injection technology, which is perfectly matched with Tula cylinder deactivation technology to further reduce the number of working cylinders. Diesel engines do not have throttle devices, but better control of fuel consumption under low load can increase efficiency by an additional 3%, which is still potentially attractive for long-distance trucks. 

    From the current situation, it may be a good choice to adopt Tula cylinder deactivation technology for all pickup trucks and SUVs equipped with V8 engines.