[Abstract] Early control systems primarily used cylinder charge quantity, fuel quality, and ignition timing as control parameters. However, many functional subsystems within the system participate in controlling the driving servo mechanism and typical automotive auxiliary functions. These devices require torque compensation during operation, often leading to conflicting demands. Early electronic fuel injection (EFI) control strategies were inadequate in handling these conflicts. This paper introduces a torque control strategy that prioritizes these conflicting demands and executes the most critical requirement, highlighting its advantage. Keywords: Torque Control Strategy, Electronic Throttle , Electronic Fuel Injection System 1. Introduction With the continuous development of electronic technology, automotive body electronic technology has also been widely developed. Furthermore, the increasing environmental awareness and rising fuel prices have placed higher demands on engine control. The quality of the Electronic Fuel Injection System (EFI) directly affects engine emissions and fuel economy. It uses an Electronic Control Unit (ECU) as the control center, utilizing various sensors installed in different parts of the engine to measure various engine operating parameters. According to the control program set in the computer by the car manufacturer, it precisely controls the injection quantity and ignition timing, ensuring the engine achieves optimal fuel mixture concentration under various operating conditions, thereby improving fuel economy and emissions. The control accuracy of the Electronic Fuel Injection System is closely related to its control strategy. This article mainly discusses torque-based control strategies. 2. Torque Control Strategy The primary task of the engine management system is to reflect driving commands in the engine's power and torque output. Whether moving at a constant speed or accelerating, the driver needs the engine to output torque to overcome the resistance during forward movement. In early engine operation, control parameters were primarily based on cylinder charge quantity, fuel quality, and ignition timing. However, many subsystems (such as idle speed control and engine speed regulation) control the driving servo mechanism and common automotive auxiliary functions (such as air conditioning). These devices require torque compensation, necessitating adjustments to the engine's output power. Most auxiliary open-loop and closed-loop control functions affect engine torque, often leading to conflicting demands. When various potentially contradictory demands occur simultaneously, coordination becomes difficult. Torque control resolves this conflict. The torque control strategy first prioritizes and coordinates the demands of each component, then uses the resulting control parameters to achieve the specified torque output. The basic function of an engine management system employing torque control is to set the corresponding torque output according to the driver's intentions. Specifically, it uses the accelerator pedal position sensor to reflect the driver's current driving intentions. The central electronic control unit (ECU) interprets the current accelerator pedal position sensor measurement as corresponding to a specific output torque. To obtain this corresponding torque, the ECU coordinates various output control signals, such as cylinder intake air volume, fuel injection volume, and ignition timing, based on the collection of various engine operating parameters and vehicle operating parameters, to achieve the required output torque. Simultaneously, the system monitors changes in current operating parameters. This control strategy can distinguish the priority of these conflicting demands and execute the most crucial ones, which is the advantage of torque-based control strategies. Engine management systems employing torque control can not only control fuel injection and ignition but also handle many complex functions, such as starting, idling, three-way catalytic converter heating, engine maximum speed limiting, boost pressure control, and component overheat protection. It can also accept requests from the drive system and vehicle dynamic control system, such as anti-vibration control, cruise control, maximum speed limiting, transmission shift optimization, and traction control. The torque regulation of a gasoline engine is shown in Figure 1. 3. Implementation of Torque Control 3.1 Implementation of Torque Control The implementation of torque control is shown in Figure 2. The ECU sets the priority levels of intake air volume and ignition timing based on driving commands and internal/external torque requirements, then calculates the actual required torque and corresponding intake air volume, and finally achieves torque output by controlling the actuators. As shown in Figure 2, the system uses two methods to adjust the output torque during torque generation: one is to change the intake air volume through the electronic throttle, a gradual transition method mainly responsible for steady-state operation. The other is a rapid response method using ignition timing adjustment or shutting off fuel injection in a certain cylinder. This method can respond very quickly to power changes during torque generation. The following mainly introduces torque control under idling conditions. At idle, the engine has no torque output; the energy generated during combustion is used to maintain the engine's operation and drive auxiliary equipment. Under this condition, the torque required to maintain operation and the idle speed together determine fuel consumption. During severe traffic congestion, a significant portion of a vehicle's fuel consumption occurs under these conditions. It is used to overcome the minimum frictional losses at idle speed, thus determining the low idle speed. Closed-loop idle speed control ensures stable and reliable operation at the set idle speed, independent of changes in other conditions. These changes can be caused by various factors, such as current fluctuations due to the electrical system, air conditioning compressor, and power steering. The control process is shown in Figure 3. Torque-based engine management systems require closed-loop idle speed control to quantitatively output power to ensure stable idle conditions under any circumstances. This results in increased power output when the speed decreases and decreased power output when the speed increases. The system will increase power output accordingly when it detects influencing factors, such as the start of the air conditioning compressor. 3.2 Electronic Throttle Control (ETC) The electronic throttle can change the intake air volume, thereby altering the torque output. Components involved in electronic throttle control include the accelerator pedal, ECU, and electronic throttle assembly. The accelerator pedal contains two potentiometers whose output signals change in the same direction, monitoring the pedal position, which is determined by the driver. The electronic throttle body includes the throttle valve, throttle actuator, and throttle opening sensor. Working process: The accelerator pedal position sensor transmits the sensed accelerator pedal position signal to the ECU. The ECU calculates the corresponding throttle opening, makes appropriate adjustments based on the current engine operating conditions, and generates a corresponding control signal, which is then transmitted to the throttle actuator of the electronic throttle assembly. The throttle actuator can respond precisely to the ECU's output control signal. Simultaneously, the two throttle position sensors feed back the current throttle opening information to the ECU, which then performs appropriate feedback control. Its control principle is shown in Figure 4. 4 Conclusion This article mainly briefly describes the torque demand of the torque control system in an automotive electronic fuel injection system. A priority approach is adopted, responding first to the torque demand of higher-priority subsystems, and then satisfying the torque demand of lower-priority subsystems, avoiding simultaneous conflicting demands. Using an electronic throttle can change the intake air volume, ultimately achieving the goal of changing torque. References [1] Huang He. Basic Principles of Automotive Electronic Injection System [M]. Shanghai Jiaotong University Press, Shanghai, 2003. [2] Feng Nenglian, Dong Chunbo, Bin Yang, et al. Research on Electronic Throttle Control System [J]. Automotive Technology, 2004, (1). Research on Electronic Injection System Based on Torque Control Strategy: PDF