Browse Publications Technical Papers 2020-01-1408
2020-04-14

Effect of a Cylinder Deactivation Actuator with Electro-mechanical Switching System on Fuel Economy of an Automotive Engine 2020-01-1408

In this paper, we present a cylinder deactivation actuator(CDA), one of the variable valve actuation mechanism, in response to strengthening CO2 and environmental regulations in major countries around the world. CDA is the most commonly used variable valve actuation system to improve the fuel efficiency and power of automotive engines, and minimizes fuel consumption by deactivating some of the cylinders during operation. Most CDA systems employ hydraulic switching systems. However, the critical problem with hydraulic switching system is that the oil temperature and pressure affect the dynamic and operating performance of the CDA system. This is a major obstacle in achieving the goal of the CDA system to improve fuel efficiency and engine performance. This paper introduces a two-step CDA mechanism equipped with an electronic switching system, which can be applied to OHC valve trains with end pivot rocker arms and can operate two valves simultaneously with a single cam. In addition, roller bearings are applied to the base cam contacts in order to fundamentally improve the wear problem which is often present in CDA mechanisms. The four-cylinder 2.0L engine with the intake port injection was selected as the engine to verify the effect of the CDA system on the fuel economy. Some modifications were also made to the engine to apply the electronic switching system to the vehicle, and a dedicated electronic control unit and control logic were developed. The engine performance analysis program and measured data were used for comparative evaluation of the engine performance and fuel consumption. To configure the combination of cylinder operations, the vibration sensor was mounted on the cylinder head and measured the vibration. Friction loss of the engine was also measured according to the operation speed and load range of the engine. The effect of the present apparatus was evaluated by measuring the fuel economy of the engine in the two test modes: fuel consumption test mode of each country and the constant-speed driving test mode. The goal of this study is to verify the effect of the cylinder deactivation actuator equipped with an electronic switching system. Therefore, experiments focused on establishing the optimum operating condition to maximize the fuel efficiency. And the optimized result was compared to the fuel consumption of the original engine without the CDA device. In the in-line four-cylinder engine, it is confirmed that deactivating cylinders 2 and 3 is the best combination to minimize vibration. The friction loss can be minimized when the CDA systems are employed on the intake and exhaust valves simultaneously. According to the optimum operating conditions, the fuel efficiency improvements of 10.3% and 8.8% was obtained in the fuel consumption test mode and the constant-speed driving test mode respectively. The optimal operating conditions were established which minimize the engine vibration, friction loss and the adverse effects on fuel efficiency. As a result, we have established optimum operating conditions for maximizing engine fuel efficiency for the CDA engines equiped with the electronic switching system.

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