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universal digital speedometer for cars
The car universal digital speedometer for cars is an application used to view driving speed, supporting two units: miles per hour or kilometers per hour. The speedometer function requires strong GPS signal support and can display a maximum speed of 220 km/h. Nowadays, many car instruments have used electronic speedometers, and a common method is to obtain signals from speed sensors on the transmission, which deflect the pointer or display numbers through changes in pulse frequency. Here are more relevant introductions: Traditional speedometers: Traditional speedometers are. A typical mechanical odometer is connected to a flexible shaft, which contains a steel wire cable. The other end of the flexible shaft is connected to a gear of the transmission, and the gear rotation drives the steel wire cable to rotate. The steel wire cable drives a magnet inside the odometer cover to rotate. The cover ring is connected to the pointer and the pointer is placed at zero position through a hairspring. The speed of the magnet's rotation causes a change in the size of the magnetic field line, and the pointer whose balance is broken is thus driven. This type of speedometer is simple and practical, and is widely used in large and small cars. However, with the development of electronic technology.
General requirements:
1 The speedometer dial should be located within the driver's direct field of view and be clear and readable day and night.
2 The speed range indicated by the speedometer should be able to accommodate the maximum speed given by the manufacturer for this type of vehicle.
3 The speed unit of the speedometer is expressed in km/h. Between 20km/h and the upper limit speed value, the graduation value should be expressed as any of 1, 2, 5, or 10 km/h. The speed value indicated on the dial should be a multiple of 20km/h.
Indication error:
The indicated speed on the speedometer shall not be lower than the actual speed. At the test speed specified in 3.6, and between these speeds, the indicated speed and the actual speed shall comply with the following relationship:
0 ≤ V1- V2 ≤ V2/10+4 km/h. In the formula: V1- indicated vehicle speed, km/h; V2- actual vehicle speed, km/h.
Test specifications:
The reference temperature at the speedometer used in the test is 23 ℃+5 ℃. The error of the test instrument used to measure the vehicle speed shall not exceed+1.0%.
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