Liquid state detection sensor
First Claim
1. A liquid state detection sensor for detecting the state of a liquid contained in a liquid container, comprising:
- a liquid condition detecting element that is to be placed in the liquid container and having a heating resistor which generates heat when a current is passed therethrough;
an energizing unit for energizing the heating resistor for a prescribed detection period;
a first corresponding value acquiring unit for acquiring, in the detection period, a first corresponding value which corresponds to a first resistance value of the heating resistor;
a temperature information acquiring unit for determining a temperature of the liquid based on the first corresponding value;
a second corresponding value acquiring unit for acquiring, after a lapse of the detection period, a second corresponding value which corresponds to a second resistance value of the heating resistor;
a difference calculating unit for determining a difference between the second corresponding value and the first corresponding value; and
a concentration acquiring unit for determining a concentration of a particular component of the liquid based on the difference between the second and first corresponding values.
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Accused Products
Abstract
A liquid state detection sensor in which temperature information of a urea aqueous solution is obtained on the basis of a voltage value acquired after the start of energization of a heating resistor corresponding to a resistance value of the heating resistor (S1-S6). Damage to the heating resistor is prevented by suspending the energization if the thus-obtained temperature is lower than or equal to the freezing point (S7: yes and S8). If the temperature is higher than the freezing point (S7: no), a voltage value corresponding to a resistance of the heating resistor after a lapse of 700 ms (S10 and S11) and a urea concentration of the urea aqueous solution are determined from a difference ΔV from the previously acquired voltage value. A more accurate urea concentration can be detected by making a correction using the previously obtained temperature information of the urea aqueous solution (S13-S18).
24 Citations
11 Claims
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1. A liquid state detection sensor for detecting the state of a liquid contained in a liquid container, comprising:
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a liquid condition detecting element that is to be placed in the liquid container and having a heating resistor which generates heat when a current is passed therethrough;
an energizing unit for energizing the heating resistor for a prescribed detection period;
a first corresponding value acquiring unit for acquiring, in the detection period, a first corresponding value which corresponds to a first resistance value of the heating resistor;
a temperature information acquiring unit for determining a temperature of the liquid based on the first corresponding value;
a second corresponding value acquiring unit for acquiring, after a lapse of the detection period, a second corresponding value which corresponds to a second resistance value of the heating resistor;
a difference calculating unit for determining a difference between the second corresponding value and the first corresponding value; and
a concentration acquiring unit for determining a concentration of a particular component of the liquid based on the difference between the second and first corresponding values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification