Sampling circuit of automotive fuel gauge and fault diagnosis method thereof

Abstract

The invention provides a sampling circuit accurate in measurement of an automotive fuel gauge and a fault diagnosis method thereof. The fault diagnosis method can improve the troubleshooting efficiency of the automotive fuel gauge and reduce the maintenance cost. The sampling circuit of the automotive fuel gauge comprises a power supply, a voltage dividing resistor, a variable resistor, a balancing resistor and a controller provided with an A/D converting unit, wherein the power supply is connected with the first end of the balancing resistor through the voltage dividing resistor, the first end of the balancing resistor serves as a first sampling point, and the second end of the balancing resistor is suspended and serves as a second sampling point. The sliding piece end of the balancing resistor is connected with the reference ground end of the power supply through the balancing resistor. The controller is connected with the first sampling point and the second sampling point respectively so as to obtain sampling voltages of the first sampling point and the second sampling point, judges whether the first sampling voltage V1 and the second sampling voltage V2 are in a predetermined normal range or not and determines that the sampling circuit breaks down if the first sampling voltage V1 and the second sampling voltage V2 exceed the predetermined normal range.

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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