Method for recognizing water boiling point with piezo-effect vibration pickups, and sensor and circuit

Abstract

The method comprises: detecting the vibration of the water; transforming the impedance; isolating the DC; amplifying the signals; filtering the high frequency; making high and low threshold re-shaping process; using a single-board to make a decision according to the pulse count. The feature of the sensor is: setting the saddle weight on one side of the copper plate of the piezoelectric effect ceramic plate; the circuit features: composed of sensor, impedance converter circuit, DC isolation circuit, amplification circuit, high frequency filter circuit, re-shaping and threshold selecting circuit and single board; the sensor is connected to the impedance transforming circuit; the impedance transforming circuit is connected to the DC isolating circuit; the DC isolating circuit is connected to the amplifying circuit; the amplifying circuit is parallel-connected to the high frequency filter circuit; the output of the amplifying circuit is connected to the re-shaping and threshold selecting circuit; the re-shaping and threshold selecting circuit is connected to the single board.

Description

technical field [0001] The invention relates to a method for detecting boiling water, in particular to a method for identifying the boiling point of water with a piezoelectric effect vibration sensor. The invention also relates to a piezoelectric effect vibration sensor implementing the method and a water boiling point detection method using the piezoelectric effect vibration sensor detection circuit. Background technique [0002] So far, there is no patent on the identification of boiling water by piezoelectric vibration sensors in heating appliances, but there are already patents on the application of vibration sensors on some household appliances that do not have the function of boiling water, such as washing machines, such as Chinese patent ZL97102158.9 , which involves the application of piezoelectric vibration sensors in washing machines. In the processing of vibration signals, this patent uses a lot of peripheral devices, including memory, a first counter, a second co...

AI Technical Summary

Problems solved by technology

This traditional measurement method has the following disadvantages: first, the sensor must be in contact with the water or the pot when used to boil water, but this method cannot be used for isolated heating appliances like induction cookers, because the temperature sensor of the induction cooker There is a layer of ceramic plate separated from the pot, so using this method to identify boiling water will lead to a large deviation. This problem has been plaguing the induction cooker industry and has not been solved for a long time; The boiling point change at altitude cannot be quickly identified, and it takes a long time to infer that the water has been boiled through complex algorithms; third, the structural design of the heating appliance using the temperature sensor is complicated, and the insulation strength of the sensor placed in the water needs to be considered to avoid electric shock ; Fourth, the heating appliances that use temperature sensors or thermostats usually set the control boiling point to a few degrees lower than the real boiling point, so the boiled water is not really boiled water; The boiling points of different products are inconsistent; sixth, the temperature sensor has time drift, which will cause the boiling point of the product to change during use

[0004] Through a large number of water boiling experiments on the induction cooker, it is found that using the vibration of the water body after the water reaches a high temperature and driving the vibration of related components, and using the piezoelectric effect vibration sensor to detect the change of the vibration signal to determine whether the water is boiling is one of the solutions to the above problems. Feasible way, but the traditional vibration sensor is not suitable for detecting the vibration signal produced by the boiling of water, as Chinese patent CN03807812.0 discloses a kind of "piezoelectric sensor", it is not developed for boiling water, as it says It is described that it is suitable for medical equipment such as stethoscopes, and its structure is relatively complicated, mainly used to detect sound signals; another example is the vibration sensor disclosed in Chinese patent CN200580016110.6, which improves the structure of the vibrating plate to improve its impact resistance The performance is not suitable for boiling water detection

Another example is a piezoelectric vibration sensor disclosed in Chinese patent ZL93247606.6, which adopts a T-shaped structure and steel balls. The vibration sensor, which adopts a spring structure, cannot detect the high-frequency boiled water output signal

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