Winter is here, the temperature drops, and many car owners will find that the automatic transmission does not shift smoothly when they start their vehicles in the morning, and sometimes they even fail to change gears. This is because the automatic transmission will enter cold protection mode at low temperatures to protect the normal operation of the transmission. So, why does an automatic transmission cold protect? What is the effect of cold protection on the vehicle? How to properly handle cold protection? This article will answer for you.
The working principle of automatic transmission is to utilize a torque converter and planetary gear set to achieve different shift ratios, so as to adapt to different driving conditions. Torque converter is a device that uses oil to transmit power, which is composed of a pump wheel, a guide wheel and a turbine, the pump wheel is connected to the engine, the turbine is connected to the gearbox output shaft, and the guide wheel is fixed on the housing. When the engine rotates, the pump wheel drives the oil to rotate, and the oil is transferred to the turbine through the guide wheel, which drives the gearbox output shaft to rotate. The torque converter can achieve continuously variable speed between the engine and the gearbox, and at the same time can also provide a certain torque amplification effect.
However, torque converters also have the disadvantage of generating a certain amount of energy loss, which leads to an increase in oil temperature. In order to prevent the oil from overheating, the automatic transmission is equipped with an oil temperature sensor to monitor the temperature of the oil and control the circulation and cooling of the oil through a computer. When the oil temperature is too high, the computer will open the oil cooler valve to introduce the oil into the oil cooler for cooling, and will also adjust the shift strategy to reduce the engine speed and reduce the heat input of the oil. This is the thermal protection mode of the automatic transmission.
So, why does an automatic transmission cold protect? The reason is actually the temperature of the oil. In winter, when the temperature is low, the viscosity of the oil will increase, and the fluidity will decrease, resulting in the oil can not effectively transmit power, nor can it fully lubricate the various parts of the gearbox, thus affecting the working efficiency and life of the gearbox. In order to avoid this, the automatic transmission will enter the cold protection mode at low temperatures, that is, delay the shift, increase the engine speed, increase the heat input of the oil, and make the oil heat up to the normal working range as soon as possible. In this way, the fluidity and lubricity of the oil can be guaranteed, and the damage caused by the oil overcooling can be avoided.
There are two main aspects of the impact of cold protection on the vehicle, one is the power performance, and the other is the fuel consumption. Because the cold protection delays shifts and increases engine speed, the vehicle's dynamic performance is improved, acceleration is faster, and climbs are easier. However, this can also lead to an increase in fuel consumption, especially in short distances, where the oil heats up for a longer time, the cooling protection time is longer, and the increase in fuel consumption is also more obvious. Therefore, there are pros and cons to the impact of cold protection on the vehicle, which needs to be weighed by the owner according to his actual situation.
So, how do you get cold protection right? In fact, cold protection is a self-protection mechanism of automatic transmission, which is a normal phenomenon and does not need to be overly worried. As soon as the oil heats up to a certain level, the cooling protection is automatically lifted and the gearbox returns to normal shifting mode. Therefore, when the owner starts the vehicle in winter, do not rush to drive, it is best to let the engine idle for a few minutes first, let the oil preheat, and then start slowly, avoid sharp acceleration, sharp braking, sharp turning and other drastic operations, so as not to cause unnecessary damage to the gearbox. At the same time, it is also necessary to pay attention to changing the transmission oil regularly to maintain the cleanliness and quality of the oil and prolong the service life of the transmission.
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