Liquid level indicating system and contact resistance washing circuit
A liquid level and resistance technology, applied in the field of electronics, can solve the problems of increase, inaccurate liquid level indication of liquid level instruments, and high cost, and achieve the effects of accurate correspondence, improved signal quality, and cost savings.
Active Publication Date: 2012-01-04
UNITED AUTOMOTIVE ELECTRONICS SYST
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Problems solved by technology
[0003] However, due to corrosion and other reasons, the contact resistance Rcontact of the contact will increase, the total resistance value output by the two-wire liquid level sensor will change, and the relationship between liquid level height and resistance value will be disordered, resulting in inaccurate liquid level indication of the liquid level instrument. .
[0004] In order to prevent the inaccurate liquid level indication of the liquid level instrument due to the increase of the contact resistance Rcontact of the contact, it is usually realized by improving the material (such as increasing the amount of precious metal used in the conductive band or the contact), but the cost is high
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[0065] An embodiment of the liquid level indicating system of the present invention is as follows: figure 2 As shown, including two-wire liquid level sensor, liquid level instrument, contact resistance flushing circuit;
[0066] One end of the conduction tape of the two-wire liquid level sensor is connected to the liquid level signal terminal of the liquid level instrument, and the liquid level instrument outputs a periodic pulse voltage to the two-wire liquid level sensor through the liquid level signal terminal , the contact of the two-wire liquid level sensor is grounded, and the liquid level meter calculates the corresponding resistance between one end of the conduction band and the contact according to the sampling voltage at one end of the conduction band when the pulse high level is generated. value, giving an indication of the corresponding liquid level.
[0067] The flushing signal terminal of the contact resistance flushing circuit is connected to the liquid level ...
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The invention discloses a liquid level indicating system, which comprises a two-wire liquid level sensor, a liquid level instrument and a contact resistance washing circuit, wherein the washing signal end of the contact resistance washing circuit is connected with a liquid level signal end of the liquid level instrument; and when a periodic pulse falling edge generated by the liquid level instrument arrives, the washing signal end of the contact resistance washing circuit delays set pulse delay time to output a washing pulse. The invention also discloses the contact resistance washing circuit. In the liquid level indicating system, high direct-current voltage is led into the two-wire liquid level sensor to puncture contact resistance; and the two-wire liquid level sensor is washed by heavy current to improve the signal quality of the two-wire liquid level sensor, so that the corresponding relation of liquid level height and a resistance value is accurate, and the liquid level instrument can indicate liquid levels accurately.
Description
technical field [0001] The invention relates to electronic technology, in particular to a liquid level indicating system and a contact resistance flushing circuit. Background technique [0002] Common liquid level indication systems, such as the liquid level indication system of automobile fuel pumps, include two-wire liquid level sensors and liquid level gauges. Such as figure 1 As shown, the principle of the two-wire liquid level sensor is a sliding rheostat, and one end of the conduction band of the two-wire liquid level sensor is connected to the liquid level signal end of the liquid level instrument, and the liquid level instrument is connected to the liquid level signal end of the liquid level instrument through a series resistance Rcons The periodic pulse voltage is output from the liquid level signal terminal to the two-wire liquid level sensor, the contact of the two-wire liquid level sensor is grounded, and when the liquid level changes, the contact The contact p...
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IPC IPC(8): G01F23/24G01F25/00
Inventor 查桢白日光屈晨竹
Owner UNITED AUTOMOTIVE ELECTRONICS SYST