JP2003130711A - Water level sensor and water sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water level sensor which is neither influenced by the ambient temperature nor by an external magnetic field, and enhances the reproducibility of a measurement accuracy. SOLUTION: The water level sensor is constituted of a diaphragm 10 which is expanded and contracted according to a pressure difference, a shaft 6 which is moved rectilinearly so as to be interlocked with the diaphragm 10, a magnetic substance core 8 held inside the shaft 6, and a differential-transformer transducer whose output is changed according to the position of the core 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential transformer type water level sensor and a water amount sensor, which are suitable mainly for detecting the water amount in an electric pot.

[0002]

2. Description of the Related Art In recent years, a pot using an electric pump has become mainstream, and accordingly, a water level sensor and a water amount sensor are mounted. FIG. 3 is a schematic diagram showing the configuration of the water level sensor. As shown in FIG. 3, the container 5 and the communication pipe 3 are connected to each other at the bottom, and the communication pipe 3 is divided into an electric pump 2 and a water level sensor 4. As shown in FIG. 5, a conventional water level sensor includes a diaphragm 16 that expands and contracts according to a pressure difference between the inside and outside of the water level sensor, a shaft 12 that linearly moves in conjunction with the diaphragm, and a magnet 15 attached to the shaft. The Hall element 14 whose output voltage changes according to the position of the magnet, and the Hall element output changes according to the pressure to be detected depending on the water level.

[0003]

In the above-mentioned conventional water amount detection, the unbalanced voltage of the Hall element changes due to the change of the ambient temperature and the influence of the external magnetic field, and there is a problem in the reproducibility of the measurement accuracy.

Therefore, an object of the present invention is to provide a water level sensor and a water amount sensor which are not affected by the ambient temperature and are not affected by an external magnetic field and which have improved reproducibility of measurement accuracy.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a water level sensor having a diaphragm that expands and contracts according to the pressure difference between the inside and outside, and a differential transformer whose output changes according to the position of the core. The output of the differential transformer is determined by the displacement of the core and is stable with respect to temperature and disturbance of the external magnetic field, so that it is possible to reduce changes in pressure measurement accuracy.

According to the present invention, it is possible to obtain a sensor output which is less affected by the ambient temperature and the external magnetic field.

That is, according to the present invention, a diaphragm that expands and contracts according to a differential pressure, a shaft that linearly moves in conjunction with the diaphragm, a magnetic core held in the shaft, and a position of the magnetic core. It is a water level sensor composed of a differential transformer whose output changes accordingly.

The present invention is also the water level sensor, wherein the magnetic core is made of a ferrite material.

The present invention is also the water level sensor, wherein the magnetic core is made of a metallic material.

According to the present invention, in the water level sensor, an external screw is provided, a spring is interposed between the magnetic core and the external screw, and the position of the magnetic core is adjusted by the external screw. Is.

Further, the present invention is a water amount sensor having a calculation unit for calculating the numerical value of the water level obtained by the water level sensor described above and the numerical value of the shape of the container of the measured water amount.

[0012]

EXAMPLE A water level sensor and a water amount sensor according to an example of the present invention will be described below.

(Embodiment 1) FIG. 1 is an explanatory view of a differential transformer of a water level sensor according to an embodiment of the present invention. The differential transformer of the water level sensor shown in FIG. 1 includes a diaphragm 10 that expands and contracts according to a differential pressure of an object to be measured (water), a shaft 6 that linearly moves in association with the diaphragm 10, and a magnetic core attached to the shaft 6. 8 and primary coil 9a and secondary coil 9
b and 9c, the differential output of the secondary coils 9b and 9c changes according to the position of the magnetic core 8.
In the water level sensor, the magnetic core 8 is made of a ferrite material or a metal material.

In the differential transformer of the water level sensor,
An external screw 11 is provided on the outer wall 17, a spring 7 is interposed between the magnetic core 8 and the external screw 11, and the position of the magnetic core 8 is adjusted by the external screw 11.

FIG. 2 is a connection diagram of coils of the differential transformer shown in FIG. An exciting current is passed through the primary coil 9a, and its output is detected by the secondary coil 9b and the secondary coil 9c. The larger the magnetic core 8 is, the higher the voltage becomes. Since the secondary coil 9b and the secondary coil 9c are connected in opposite phases, the output voltage becomes zero when the magnetic core 8 is located at the position where the secondary coil 9b and the secondary coil 9c are equally divided. When the magnetic core 8 is displaced from this midpoint to either direction, an output voltage proportional to the displacement is detected.

Here, the external screw 1 is attached to the outer wall of the differential transformer.
1 is provided, but the offset voltage is set to the minimum value by adjusting the external screw 11.

FIG. 3 is a schematic view showing a structure mounted on an electric pot using a water level sensor. The configuration of FIG. 3 may be the same as the conventional one. As shown in FIG. 3, the container 5 of the electric pot and the communication pipe 3 are connected at the bottom respectively, and the electric pump 2 for pumping the water in the communication pipe 3 and the container 5 and the water level for detecting the water level of the water in the container The sensor 4 is connected.

FIG. 4 is a diagram showing the relationship between the displacement of the water level sensor of the present invention and the output voltage. Since the output voltage is constantly detected in this manner, the water level of the electric pot can be continuously detected from the relationship shown in FIG.

(Embodiment 2) A water amount sensor according to an embodiment of the present invention will be described below. The water amount sensor of the present invention uses the configuration of the water level sensor described in the first embodiment, and has a configuration in which a calculation unit is added in the circuit unit.

That is, a water amount sensor is constructed by adding a calculation unit for calculating a numerical value relating to the shape of the container of the measured water amount and the detected water level value to the circuit portion of the water level sensor of the first embodiment.

Here, as the container for the measured water amount, there is an electric pot, a washing machine, a bath tub, or the like.
The amount of water is calculated by selecting the numerical value of the shape suitable for these.

[0022]

As described above, according to the present invention,
It is possible to provide a water level sensor and a water amount sensor that can obtain a sensor output that is less affected by ambient temperature and an external magnetic field.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a differential transformer of a water level sensor according to an embodiment of the present invention.

FIG. 2 is a connection diagram of coils of the differential transformer shown in FIG.

FIG. 3 is a schematic diagram showing a configuration in which the water level sensor of the present invention and the conventional water level sensor are mounted on an electric pot.

FIG. 4 is a diagram showing a relationship between displacement and output voltage of the water level sensor of the present invention.

FIG. 5 is a schematic diagram showing a configuration of a conventional water level sensor.

[Explanation of symbols]

1 Pumping pipe 2 Electric pump 3 communication pipe 4 Water level sensor 5 containers 6 shafts 7 spring 8 Magnetic core 9a Primary coil 9b, 9c secondary coil 10 diaphragm 11 External screw 12 shafts 13 spring 14 Hall element 15 magnets 16 diaphragm 17 outer wall

Claims (5)

[Claims] 1. A diaphragm that expands and contracts according to a differential pressure,
A shaft that linearly moves in conjunction with the diaphragm,
A water level sensor comprising: a magnetic core held in the shaft; and a differential transformer whose output changes according to the position of the magnetic core. 2. The water level sensor according to claim 1, wherein in the water level sensor, the magnetic core is made of a ferrite material. 3. The water level sensor according to claim 1, wherein in the water level sensor, the magnetic core is made of a metallic material. 4. The water level sensor is provided with an external screw, a spring is interposed between the magnetic core and the external screw, and the position of the magnetic core is adjusted by the external screw. Item 5. The water level sensor according to any one of items 1 to 3. 5. A water amount sensor having a calculation unit for calculating the numerical value of the water level obtained by the water level sensor according to any one of claims 1 to 4 and the numerical value of the shape of the container of the measured water amount. .