A sampling circuit and fault diagnosis method of a vehicle fuel meter

Abstract

The invention provides a sampling circuit of a vehicle fuel meter with accurate measurement and a fault diagnosis method thereof. The fault diagnosis method can improve the troubleshooting efficiency of the vehicle fuel meter and reduce maintenance costs. The sampling circuit of the vehicle fuel meter of the present invention comprises a power supply, a voltage dividing resistor, a variable resistor, a balancing resistor and a controller with an AD conversion unit, and the power supply passes through the first connection between the voltage dividing resistor and the balancing resistor. The first end of the balance resistor is used as the first sampling point, the second end of the balance resistor is suspended and used as the second sampling point; the slider end of the balance resistor is connected to the reference ground end of the power supply through the balance resistor ; The controller is respectively connected to the first sampling point and the second sampling point to obtain the sampling voltages of the first sampling point and the second sampling point. It is also judged whether the first sampling voltage V1 and the second sampling voltage V2 are within a predetermined normal range, and if they exceed the predetermined normal range, it is judged that the sampling circuit is faulty.

Description

technical field [0001] The invention belongs to the technical field of liquid level height measurement, and in particular relates to a sampling circuit of a vehicle fuel gauge and a fault diagnosis method thereof. Background technique [0002] The fuel gauge for vehicles is mainly composed of an oil level indicator and an oil level sensor. The oil level indicator indicates the oil level position according to the resistance value of the oil level sensor. At present, a sliding rheostat is often used as an oil level sensor to obtain the oil level. Height information, the specific method is that the sliding plate of the sliding rheostat moves correspondingly with the height of the oil level, thereby changing the resistance value of the sliding rheostat. Such as figure 1 As shown, the power supply v is connected to the slider end of the variable resistor Rx through the current limiting resistor R, and according to the sampling voltage V1 and the known power supply voltage V and ...

AI Technical Summary

Problems solved by technology

This kind of measurement circuit and measurement method has the following problems: due to immersion in oil, there is contact resistance between the sliding plate of the variable resistor and the conductive band of the variable resistor, so that the value of R' is affected and cannot accurately reflect the remaining oil volume

In addition, the voltage is different from the reference GND of the variable resistor, which will cause the value of V-V1 to be inaccurate and also affect the accuracy of R’

[0003] In the above measurement circuit, once a fault occurs, it is cumbersome to troubleshoot the problem point

Sometimes the method of directly replacing the instrument or oil pump is used to quickly troubleshoot, which not only increases the maintenance cost, but also increases the failure rate of parts

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