Differentiate between various operation modes of the start-stop system

    Everyone may be familiar with the term "start-stop system", but there may be some misunderstandings about it, thinking that all start-stop systems work in the same way. Nowadays, start-stop systems are used not only in pure electric vehicles and hybrid vehicles, but also in traditional internal combustion engines. Its basic function is to save automobile fuel consumption and reduce exhaust emissions.

    Most commonly, it automatically shuts off the engine when the car comes to a stop and restarts it instantly when it needs to be started.

    The start-stop system was first invented in the 1930s, and Volkswagen and Fiat were the first to equip mass-produced cars with this technology. More than 10 years ago, Honda and Toyota also equipped the models introduced to the United States with the start-stop system. For traditional internal combustion engines, the start-stop system has a general effect on energy saving and emission reduction. Different car companies have different names for it. Ford calls it "Auto Start-Stop" and Mercedes-Benz calls it "Eco Start/Stop". Depending on the design of the system and the driving environment, the start-stop system can improve the fuel efficiency of the car by 3-10%. Combined with other technologies such as brake energy recovery, direct fuel injection, electronic power steering, and electric air-conditioning compressors, it can improve the fuel efficiency of the car by 15-25%.

    There are many different ways that start-stop systems work, and automakers adjust them based on the structural complexity and cost of the vehicle.

    Lux Research, an automotive industry research company, has analyzed the start-stop system for many years and divided the start-stop system into three types: micro start-stop system, medium start-stop system, and strong start-stop system.

Micro start-stop system

    The micro start-stop system has the lowest cost and the simplest structure. This type of system uses a high-durability starter and a battery with a large power capacity. The engine controller needs to reprogram the electronic control system of the injection system, starter and transmission to quickly start the vehicle when the driver releases the brake pedal or steps on the accelerator pedal. In manual models, the node for restarting the engine is when the driver steps on the clutch pedal.

    Most micro start-stop systems offer a driver-adjustable switch, and some systems incorporate an auxiliary battery to prevent the interior lighting from dimming momentarily and the air conditioning system from lacking power when the engine power is cut off.

    Usually only traditional internal combustion engines use this type of system. Due to its simple mechanical structure, the cost of the micro start-stop system is about $300-400. If used in urban road conditions with frequent start-stop, the fuel economy improvement effect is about 3-5%.

Medium level start-stop system

    Similar in structure to a mild hybrid system, it uses a starter, a larger battery, and an auxiliary battery. In many mild start-stop systems, an enhanced AC motor is used to regenerate braking energy to power a small lithium-ion auxiliary battery.

2014 Mazda i-ELOOP adopts mid-start stop system

    The cost of a moderate start-stop system is about $500-700. It can improve vehicle fuel efficiency by 7-12% in urban conditions.

Powerful start-stop system

    This type of start-stop system usually uses a belt-driven AC starter (Belt Alternator Starter), which is called a belt-driven starter generator (Belt-Driven Starter-Generator) in Europe.

    A belt-driven AC starter is added to the belt drive system of a traditional internal combustion engine. It replaces the generator/motor function of the original belt-driven AC generator. Therefore, when the engine drives the motor to rotate, the motor acts as a generator to charge the independent battery pack. When the engine needs to start, the motor transfers its torque to the engine through the belt instead of through the traditional starter. The independent battery pack can also be charged by the brake energy regeneration system.

    The motor/generator in the forced start-stop system is larger than a traditional starter, so it can provide greater torque to the engine when it starts, shortening the engine restart time.

Malibu Eco adopts strong start-stop system

    The brake assist system is a very complex system. In addition to the start-stop function, it can also improve the vehicle's fuel economy even on highways by cutting off the fuel supply when the vehicle is at a high speed or decelerating, allowing the vehicle to enter a "coasting" state. Some start-stop systems can also provide additional auxiliary electrical energy when the vehicle is accelerating, converting it into mechanical energy to work with the engine to drive the vehicle forward. Such systems can generally be seen in micro-hybrid vehicles.

    When the brake assist system is installed in a powertrain equipped with an automatic transmission, an additional auxiliary electric oil pump is used in the transmission to ensure that the oil in the transmission remains flowing when the engine is stopped, so that it can quickly enter normal working state when it is started next time.

    The forced start-stop system costs about $1,000-1,200 and improves fuel efficiency by approximately 15-25%.