Do you know that car tachometers also have these functions?

Do you know that car tachometers also have these functions?

In a car, there are two largest instruments, the speedometer and the tachometer. They are generally installed symmetrically in the center of the dashboard, occupying most of the dashboard. The speedometer is of great concern to everyone. On the one hand, it is used to display the speed of the car to avoid speeding violations; on the other hand, it can display the mileage traveled. But many people don't know how to use the tachometer, and even think it is redundant. In fact, the tachometer is very important to the car. Today we will talk about what the tachometer of the car is used for.

How does the tachometer work? There is a crankshaft speed sensor on the engine, which emits a pulse signal as the engine crankshaft rotates (some gasoline engines take the ignition pulse signal). This signal is transmitted to the engine computer, and after calculation, a control signal is output and sent to the tachometer to control the rotation of the drive stepper motor on the tachometer (the pointer is directly installed on the rotation axis of the stepper motor). The faster the engine rotates, the more pulses it generates, and the greater the speed value displayed on the meter. In order to accurately display the rotation speed, the stepper motor moves only 1/3 degree.

In order to drive the car well, you need to look at the tachometer. The tachometer can visually display the engine's speed under various working conditions. The driver can know the engine's operation at any time and grasp the timing of shifting gears. The transmission gear and throttle position keep the car in the best working condition. The reason is simple. If you don't shift gears when the speed is too low, the car will be in a stalled state and may even cause stalling. I wonder if car owners have ever observed the speed values ??at the moment of ignition, starting, and shifting gears. What are they?

During the cold start process, the warm-up process after starting, the level of idle speed after warm-up, the stability of idle speed, the pattern of idle jitter, etc., can all be seen through the tachometer. ; Can intuitively see whether the engine is in good condition.

Please see the tachometer for the timing of shifting gears. In the past, instructors who learned to drive would say that they should add or subtract gears according to the vehicle speed. This method is actually wrong. Each gearbox has different gear ratio settings. If the vehicle speed is the same, each vehicle has a different transmission. Ratio setting, so changing gears according to vehicle speed will only consume more fuel as you drive. The most correct method is to determine the timing of shifting based on engine speed.

How to grasp the best time to shift gears in a manual transmission car? Friends who like strong power can downshift first and then shift gears at high speeds. Friends who like higher fuel economy can shift gears at low speeds and try to keep the speed below 3000 rpm, about 2500 rpm. about. For automatic transmission models, manual shifting mode has been used to control gears, and the method is the same as manual transmission models.

The moment of ignition. For a four-cylinder gasoline engine, successful ignition can be ensured when the speed reaches 80r/min, but in fact, the general starter can drive the engine's starting device to reach 120r/min. If it is a V6 engine, the starting speed will be higher, usually above 140r/min.

At too high speed, the engine's lubrication and heat dissipation effects are not good. If the speed is too high and exceeds the endurance of some engine parts, it will cause damage to these parts. Therefore, early cars had a red line area on their tachometers to remind the driver. At this time, the engine is working in an unsafe area. If the wave continues, the engine will be lost.