JP2015102348A - Liquid level detection method and detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detecting method and apparatus for use in a liquid container that can solve a problem encountered in increasing the number of magnetic sensor chips and that of liquid levels, namely the problem that, if the positions of adjoining magnetic sensor chips are extremely close to each other, fluctuations in the sensitivity of magnetic sensor chips invite reversal of the order in which the magnetic sensor chips sense magnetism.SOLUTION: In detecting the magnetism of a magnetic substance fitted to a float buoyant in a liquid surface with a plurality of magnetic sensor chips MR arranged at certain vertical spacing, either a liquid level detecting method is used by which one row is composed of magnetic sensor chips in a number corresponding to the number of liquid levels, two rows of magnetic sensor chips are arrayed, magnetic sensor chips of which the upper and lower ones are in the same order constitute one set, and information is processed only when both of the two magnetic sensor chips constituting each set have sensed magnetism, the two being assumed to have sensed magnetism, or a logic circuit 5 that performs such processing is provided in a liquid level detecting apparatus.

Description

  The present invention divides the liquid level in the liquid container into a number of stages, and detects the magnetism of the magnetic material attached to the float floating on the liquid level with a large number of magnetic sensor chips arranged vertically at regular intervals. The present invention relates to a liquid level detection method and a detection apparatus for detecting in which stage a liquid level is located.

  There are various methods for detecting the liquid level of the liquid contained in the container. Sensors employing various methods such as magnetic sensor chips, electrode sensors, magnetostrictive methods, ultrasonic vibration methods, and magneto-optical methods are actually used.

As the liquid level of the container, two points are particularly important: the highest rise point (water is full) and the lowest drop (water is drought). Therefore, devices that emit a signal (warning for drought or full water) when the liquid level reaches one of the two points are commercially available. In the case of detecting only the two points, an inexpensive magnetic sensor chip (eg, MR sensor) having a relatively simple structure that determines only whether or not magnetism is sensed can sufficiently function.
Specifically, a magnetic sensor chip is installed at the highest point and the lowest point of the liquid level in the container, and a float attached with a magnetic body is floated on the liquid level. When the liquid level reaches the highest point or the lowest point, the magnetic sensor chip senses the magnetism of the magnetic material and generates a signal.

  On the other hand, a specific numerical value of the liquid level may be obtained also when the liquid level is located between the highest point and the lowest point. When a numerical value of the liquid level is required, a sensor capable of performing more detailed measurement is often used. However, there is also a demand for an apparatus that can measure an intermediate liquid level between the highest point and the lowest point using an inexpensive magnetic sensor chip, and specific products have been proposed and marketed.

Patent Document 1 discloses a water level detection device comprising a hollow guide member, a float with a magnet attached thereto, a plurality of magnetic sensor chips, a circuit for reading the position of the magnet, and a circuit for transmitting the output of this circuit to a remote place. Is disclosed (Claims).
The water level detection device described in Patent Document 1 is used to control output in a hydroelectric power plant (industrial application field in the lower left column on page 1), and a circuit for transmitting output required for this purpose to a remote location It has. However, the contents other than the circuit that transmits the output to a remote place are the same as those of a general liquid level detection device that is small.

Patent Document 2 discloses a liquid level detecting device (utility model registration claim) including a float, a detected object (magnet piece), a predetermined number of sensors, a transparent case, and a liquid level output unit.
In the device described in Patent Document 2, a float and a detected object are accommodated inside a transparent case (glass tube), and the transparent case functions as a guide member that restricts the movement direction of the float (summary and FIG. 1). ). In addition, the float and the object to be detected are connected with a connecting rod, so that the object to be detected and the sensor are arranged so as to be positioned above the liquid level and the scale can be visually observed. (Abstract and Figure 1).

Patent Document 3 discloses a magnetic liquid level gauge (Claim 1 and FIG. 2) including a storage case, a liquid introducing portion having a float, a first magnet, and a second magnet, and a number of magnetoresistive elements. Disclosure.
The invention described in Patent Document 3 uses a (quantitative) magnetoresistive element (resistance) whose resistance value changes according to the lines of magnetic force formed by the two types of magnets.

Patent Document 4 determines the liquid level in the liquid tank based on a combination of a liquid tank, a float with a magnet, a plurality of magnetic sensor chips arranged at intervals above and below, and detection signals from the plurality of magnetic sensor chips. An apparatus for detecting a liquid level in a liquid tank including a liquid level determination unit (claim 1) is disclosed.
The invention described in Patent Document 4 is characterized in that it can detect the liquid level divided into a number of stages larger than the number of magnetic sensor chips (effect of the invention).

Non-Patent Document 1 discloses a commercially available liquid level detector (HL-A) that uses a large number of magnetic sensor chips.
A device (HL-A) described in Non-Patent Document 1 includes a donut-shaped float in which a magnetic material is accommodated; a shaft-shaped guide member that passes through a hollow portion of the donut-shaped float; A substrate having a length corresponding to a range in which the magnetic body can move up and down (eg, 50 mm); attached to the substrate at regular intervals (5 mm intervals) to detect magnetism A large number (eg, 10) of magnetic sensor chips that output a signal corresponding to whether or not the liquid level is detected; the liquid level is determined based on the signal output from the magnetic sensor chip, and a signal corresponding to the liquid level (specification) The voltage is determined by a determination unit.

  The apparatus (HL-A) described in Non-Patent Document 1 uses an inexpensive magnetic sensor chip and is characterized in that the liquid level can be measured with relatively high accuracy (in units of 5 mm). The output accuracy (5 mm) at the liquid level is a value corresponding to the interval (5 mm) between magnetic sensor chips arranged at equal intervals on the substrate.

JP-A-1-257223 Japanese Utility Model Publication No. 5-57629 JP 2009-236615 A JP 2011-220724 A

WATTY Co., Ltd., Sensor list, Float switch (for water and chemicals), HL-A, [Search on November 18, 2013], Internet <URL: http://www.watty.co.jp/sensor/hl -l.html>

Regarding the apparatus (HL-A) described in Non-Patent Document 1, there is a demand for more precise liquid level output accuracy. As described above, the output accuracy (5 mm) at the liquid level of this apparatus is a value corresponding to the interval (5 mm) between the magnetic sensor chips arranged at equal intervals on the substrate. Therefore, in order to make the output accuracy at the liquid level more precise (less than 5 mm), a means for reducing the interval between the magnetic sensor chips by using a larger number of magnetic sensor chips can be considered.
However, as a result of the inventor's research, it has been found that if a larger number of magnetic sensor chips are used to reduce the distance between the magnetic sensor chips, there is a high possibility that a serious problem occurs in the measurement. Commercially available magnetic sensor chips are inexpensive but often have low sensitivity uniformity. Therefore, when the interval between the magnetic sensor chips is reduced (for example, to 2.5 mm), the magnetic sensor chip located farther from the magnetic body senses magnetism first than the magnetic sensor chip located closer to the magnetic body. Problems can occur (the order of sensing is reversed).

An object of the present invention is to divide a range in which a liquid surface level fluctuates in a liquid container into a plurality of stages, and to arrange a plurality of magnetic sensors in which magnetism of a magnetic body attached to a float floating on the liquid surface is arranged at regular intervals. In the liquid level detection method for detecting which level the liquid level is located by detecting with the chip, there is a problem that occurs when the number of magnetic sensor chips and the number of levels of the liquid level are increased, that is, adjacent It is to solve the newly found problem that when the positions of the matching magnetic sensor chips are very close, the order in which the magnetic sensor chips sense magnetism is reversed due to variations in sensitivity of the magnetic sensor chips.
The object of the present invention is to solve the problem that the order in which the magnetic sensor chip senses magnetism is reversed due to variations in the sensitivity of the magnetic sensor chips that occur when the positions of adjacent magnetic sensor chips are extremely close to each other. It is also providing a level detection device.

The present invention
A method for detecting the level of a liquid contained in a liquid storage container having a liquid supply port and / or a liquid discharge port, the method including the following steps:
A liquid storage container having a liquid supply port and / or a liquid discharge port, a float guide cylinder vertically disposed inside the container, and outside or inside the guide cylinder so as to be able to move up and down along the guide cylinder Mounted magnetic float, long shape with at least 6 magnetic sensor chips arranged on the inside or outside of the guide cylinder in parallel with the guide cylinder and fixed at regular intervals in the vertical direction Providing a liquid storage device with a liquid level detecting device including a substrate and a liquid level detecting device including a magnetic signal detecting / processing circuit electrically connected to each of the magnetic sensor chips;
Storing the liquid in the container;
The step of detecting the level of the liquid level contained in the container by a method including the following operations and processes:
1) An operation for detecting the magnetic signal of the magnetic float moved on the surface of the liquid in the container by buoyancy by the magnetic sensor chip,
2) In the magnetic signal detection / processing circuit, the magnetic signal detected by each magnetic sensor chip is set as a unit of a magnetic sensor chip set composed of two or more magnetic sensor chips located in close proximity to each other, Only when all the magnetic sensor chips included in the unit have received a magnetic signal, a process for recognizing that the magnetic sensor chip set of the unit has received a magnetic signal from the magnetic float, and 3) Confirmed in advance Based on the relationship between the position of the unit of the magnetic sensor chip set and the liquid level, the liquid level is determined from the position of the unit of the magnetic sensor chip set that is recognized as having received the magnetic signal from the magnetic float in step 2). Processing to detect the level of.

The said method can be implemented with the following aspects.
The magnetic float is a ring-shaped magnetic float mounted on the outside of the guide cylinder, and a long substrate having a magnetic sensor chip on the surface is disposed inside the guide cylinder.
The same number of the magnetic sensor chips is provided on each of both side surfaces of the elongated substrate.
The magnetic sensor chip provided on one surface of the elongate substrate and the magnetic sensor chip provided on the other surface are arranged so that their heights are not the same.
The magnetic sensor chip set includes a chip corresponding to the nth chip from the lowermost chip of the magnetic sensor chip provided on one surface and a chip corresponding to the nth chip from the magnetic sensor chip provided on the other surface. Is done.

The present invention also provides:
A liquid level detecting device for detecting a liquid level of a liquid stored in a liquid storage container having a liquid supply port and / or a liquid discharge port, which is vertically arranged inside the container. Float guide cylinder, magnetic float mounted on the outside or inside of the guide cylinder so that it can move up and down along the guide cylinder, on the inside or outside of the guide cylinder, arranged in parallel with the guide cylinder, etc. Liquid level detection including an elongated substrate having at least six magnetic sensor chips arranged and fixed at intervals on the surface, and a magnetic signal detection / processing circuit electrically connected to each of the magnetic sensor chips An apparatus is provided, however, the same number of magnetic sensor chips are provided on each of both side surfaces of the elongated substrate.

The said apparatus can be implemented with the following aspects.
The magnetic float is a ring-shaped magnetic float mounted on the outside of the guide cylinder, and a long substrate having a magnetic sensor chip on the surface is disposed inside the guide cylinder.
The magnetic sensor chip provided on one surface of the elongate substrate and the magnetic sensor chip provided on the other surface are arranged so that their heights are not the same.

  Furthermore, the present invention divides the range in which the liquid level changes in the liquid container (8) into a number of stages, and the magnetism (11) attached to the float (1) floating on the liquid surface (91) ( Magnetic signal) is detected by a large number of magnetic sensor chips arranged at regular intervals above and below, and based on the signal output by the magnetic sensor chip, it is detected which level the liquid level is located. The number of magnetic sensor chips (MR1 to MR24) is a plurality of times (n times: n is an integer greater than or equal to 2) the number of stages at the liquid level. The signal to be output is processed as if the group sensed magnetism only when the plurality of magnetic sensor chips constituting each group sensed magnetism. Detect if is Providing liquid level detection method according to claim.

Preferably, the number of magnetic sensor chips twice as many as the liquid level is used, and two magnetic sensor chips are used as one set.
The magnetic body can be accommodated in the float.

The magnetic sensor chip is preferably an MR sensor.
Preliminary measurements are made at the liquid level of each stage, and the signal patterns output by each set of magnetic sensor chips are recorded, and the signal patterns output by each set of magnetic sensor chips in actual measurement are recorded. It is possible to detect in which stage the liquid level is located based on a pattern-processed signal that is matched with a pre-recorded pattern and matched.

Furthermore, the present invention provides
A float (1) to which a magnetic body (11) is attached;
A guide member (2) that restricts the movement direction of the float (1) so that the float (1) can move in a certain range in the vertical direction and substantially immovable in the horizontal direction;
A substrate (3) attached to the guide member (2) and having a length corresponding to a range in which the magnetic body (11) can move up and down;
On average, two or more magnetic sensor chips attached to the substrate (3) are vertically arranged at intervals to detect the magnetic material within a range in which the magnetic material can move up and down, and whether the magnetic material is detected. A number of magnetic sensor chips (MR1 to MR24) that output a signal corresponding to whether or not;
A plurality of magnetic sensor chips (n: n is an integer of 2 or more) are processed as one set, and signals output from a plurality of magnetic sensor chips constituting one set are processed. The number of logic circuits (G0 to G11) corresponding to the number of sets of magnetic sensor chips that output a signal that the set has detected magnetism only when magnetism is sensed; and all the logic circuits output There is also provided a liquid level detection device comprising a determination unit (6) that determines a liquid level based on a signal to output and outputs a signal corresponding to the liquid level.

The two magnetic sensor chips are preferably set as one set.
Furthermore, it can have an attachment part for attaching the said apparatus to a liquid container.

Magnetic sensor chips can be attached to both the front and back surfaces of the substrate.
Furthermore, it can have a display part which displays a liquid level based on the signal which a determination part outputs.

The guide member has a rod shape (float guide cylinder arranged vertically inside the container), the float has a donut shape (ring shape), the guide member passes through a hollow portion of the donut shape, and the float It is preferable that a float stopper is attached to the guide member at a position corresponding to an upper limit and a lower limit of a range that can move up and down.
A board | substrate can be accommodated in the inside of the said rod-shaped guide member.

The two magnetic sensor chips constituting each set are arranged at an interval in the vertical direction, and the logic circuit of the set of 2 to 4 magnetic sensor chips on the average in the range in which the magnetic body can move up and down is magnetic. It is preferable to output a signal that the signal is detected.
When the magnetic sensor chip senses magnetism, it outputs an L level signal, and when it does not sense, it outputs an H level signal, and the logic circuit is preferably a NOR gate.

As a result of the inventor's research, the problem caused by increasing the number of magnetic sensor chips (for example, by a factor of two) unexpectedly increases the number of magnetic sensor chips (for example by a factor of two, compared with the original number). Then, it was found that the problem can be solved by increasing (by a factor of 4).
As described above, when the number of magnetic sensor chips is increased to shorten the interval between a plurality of adjacent magnetic sensor chips, the magnetic sensor chip at a position far from the magnetism comes before the magnetic sensor chip at a position near the magnetism. The problem of sensing magnetism occurs. This problem can be solved by making the sensitivity of the magnetic sensor chip uniform (for example, sieving the sensitivity and excluding the low and high sensitivity magnetic sensor chips). However, if the sensitivity is made uniform in this way, the advantage of the magnetic sensor chip that it is extremely inexpensive is lost.

  As a result of research conducted by the present inventor, it has been found that a relatively high sensitivity magnetic sensor chip is more likely to cause the problem than a relatively low sensitivity magnetic sensor chip. Therefore, in the method of the present invention, a plurality of magnetic sensor chips are set as one set, and a signal output from the magnetic sensor chip is determined only when the plurality of magnetic sensor chips constituting each set sense magnetism. Due to the relatively high sensitivity of the magnetic sensor chip, the magnetic sensor chip at a position far from the magnetism senses the magnetism before the magnetic sensor chip at a position near the magnetism. To solve the problem. Similarly, in the apparatus of the present invention, a plurality of magnetic sensor chips are processed as one set, and signals output from a plurality of magnetic sensor chips constituting one set are processed, and each of the plurality of magnetic sensor chips is magnetic. The above problem is solved by the number of logic circuits corresponding to the number of pairs of magnetic sensor chips that output a signal that the pair has sensed magnetism only when they are sensed.

It is a schematic diagram which shows the state of the container which attached the liquid level detection apparatus of this invention (the right side of a container is sectional drawing). It is a perspective view of the liquid level detection apparatus of this invention. It is sectional drawing of a guide member and a float. It is a conceptual diagram which shows the relationship between the board | substrate which has a magnetic sensor chip, a logic circuit, and the determination part.

FIG. 1 is a schematic view showing a state of a container equipped with a liquid level detection device of the present invention (the right side of the container is a sectional view).
As shown in FIG. 1, the apparatus of the present invention is used to detect the liquid level (91) of the liquid (9) contained in the liquid storage container (8). FIG. 1 shows the float (1), the guide member (2) and the mounting part (7) of the apparatus.

  The float (1) shown in FIG. 1 has a donut shape (ring shape). The guide member (2) includes a rod-like stem (21) functioning as a float guide cylinder disposed vertically inside the container, an upper stopper (22), and a lower stopper (23). And the guide member (2) has passed through the donut-shaped hollow part. With this structure, the float (1) can move within a certain range in the vertical direction (between the upper stopper and the lower stopper), but cannot move substantially in the horizontal direction (along the guide cylinder). The direction of movement is constrained so that it can move up and down.

  The float (1) has a specific gravity lighter than the liquid (9) and is molded from a substance (generally foamed plastic) that is not corroded by the liquid (9). A magnetic body (not shown) is accommodated in the float (1). By accommodating the magnetic body in the float, it is possible to prevent the magnetic body (for example, iron oxide) from eluting into the liquid.

Note that, as disclosed in Patent Document 2, the movement direction of the float can be restricted by accommodating the float in a cylindrical (eg, glass tube) guide member.
Similarly, as disclosed in Patent Document 2, the magnetic body is not accommodated in the float, and the float and the magnetic body (external to the float) are connected by a connecting rod, thereby removing the magnetic body from the liquid surface. It is also possible to arrange it so as to be located above the point. Even if the position of the magnetic body does not match the liquid level, the liquid level can be detected by correcting the obtained data.

The rod-shaped stem (21), the upper stopper (22), and the lower stopper (23) constituting the guide member (2) are manufactured from a substance (generally plastic or metal) that is not corroded by the liquid (9). A substrate, a magnetic sensor chip, a logic circuit, and a determination unit (all not shown) are accommodated in the rod-shaped stem (21).
In addition, when connecting the float and the magnetic body with the connecting rod as described above so that the magnetic body is positioned above the liquid level, the substrate, the magnetic sensor chip, the logic circuit, and the determination unit Also, it is arranged so as to be located above the liquid level. The part positioned above the liquid level does not necessarily have to be accommodated inside the guide member.

  The attachment portion (7) includes a nut (71), a thread (72), and a bolt (73), and the device is attached to the container (8) using these. The container (8) shown in FIG. 1 is provided with a liquid supply port and / or a liquid discharge port, on which a lid (81) is attached, and a handle (82) is further provided. It should be noted that the device may be attached to the container by any means without providing any attachment portion (with the attachment portion as an option).

FIG. 2 is a perspective view of the liquid level detecting device of the present invention.
As in FIG. 1, FIG. 2 shows the float (1), guide member (2), and mounting portion (7) of the apparatus. The float (1) has a donut shape. The guide member (2) includes a rod-shaped stem (21), an upper stopper (22), and a lower stopper (23). The attachment portion (7) includes a nut (71), a screw thread (72), and a bolt (73). FIG. 2 shows a state in which the nut (71) is loosened.

FIG. 3 is a cross-sectional view of the guide member and the float.
Similarly, a doughnut-shaped magnetic body (11) is accommodated in the donut-shaped float (1).

The standard dimensions of the donut-shaped float are: outer diameter: 32.0 mm, inner diameter: 11.2 mm, and height (thickness in the vertical direction): 10.0 mm. The standard dimensions of the magnetic material (similarly donut-shaped) accommodated in the float are as follows: outer diameter: 18.0 mm, inner diameter: 13.2 mm, height (thickness in the vertical direction): 3.0 mm is there.
The size of the float and the magnetic body is preferably in the range of 1/10 to 10 times the standard size, more preferably in the range of 1/5 to 5 times, and 1/2 to 2 times. It is most preferable to be within the range.

The guide member (2) includes a rod-shaped stem (21), an upper stopper (22), and a lower stopper (23). The upper stopper (22) is integrated with a bolt (73) constituting a part of the attachment portion.
A substrate (3), a logic circuit (5), and a determination unit (6) are accommodated in the rod-shaped stem (21).

A large number of magnetic sensor chips (MR1 to MR24) are attached to both the front surface and the back surface of the substrate (3). The number of magnetic sensor chips is a multiple of the number of measurement steps (eg, 12 steps) obtained by dividing the measurement range (eg, 30 mm) by the output accuracy (eg, 2.5 mm) (n times: n is an integer of 2 or more) ). The plurality (n) is preferably 2, 3, or 4, more preferably 2 or 3, and most preferably 2.
The actual measurement range and output accuracy are preferably in the range of 1/10 to 10 times the standard measurement range (30 mm) and output accuracy (2.5 mm), and are 1/5 to 5 times higher. More preferably within the range, most preferably within the range of 1/2 to 2 times.

The magnetic sensor chip to be used is preferably an MR sensor or a Hall element, and an MR sensor is particularly preferable. An inexpensive magnetic sensor chip (MR sensor or Hall element) is used as an open / close sensor of a mobile phone, and can be diverted to the apparatus of the present invention.
In the conventional apparatus, the magnetic sensor chip is attached only to one surface of the substrate. However, in the present invention, since it is necessary to use a large number of magnetic sensor chips, there is a possibility that not all of them can be attached only on one side of the substrate. In such a case, as shown in FIG. 3, it is preferable to attach a magnetic sensor chip to both the front surface and the back surface of the substrate (rather than using a plurality of substrates). In the case where a larger number of magnetic sensor chips are used than in the case of FIG. 3 (for example, n is 3 or more), the substrate is formed into a polygonal column (triangular column, quadrangular column) or a column, and there are a large number around it The magnetic sensor chip may be attached in a spiral shape.

The determination unit (6) shown in FIG. 3 includes a signal / serial conversion circuit (61), a microcontroller (63), and a D / A converter (65).
In addition to the liquid level in the container, the temperature of the liquid is often important information to be managed for the liquid in the container. Therefore, it is preferable to install a thermometer inside the guide member and output the temperature information together with the liquid level information.

FIG. 4 is a conceptual diagram showing the relationship between a substrate having a magnetic sensor chip, a logic circuit, and a determination unit.
A large number of magnetic sensor chips (MR1 to MR24) are attached to both the front surface and the back surface of the substrate (3). FIG. 4 shows the substrate (3) horizontally, but actually, as shown in FIG. 3, MR1 is at the bottom and MR24 is at the top. In the present invention, the number (eg, 24) of magnetic sensor chips obtained by multiplying the number of measurement steps (eg, 12 steps) by n (eg, n = 2) is used. Odd-numbered magnetic sensor chips (MR1, MR3 to MR21, MR23) attached to one surface of the substrate form one row, and the magnetic sensor chips are arranged at equal intervals in one row. The even numbered magnetic sensor chips (MR2, MR4 to MR22, MR24) attached to the other surface of the substrate form another row, and the magnetic sensor chips are arranged at equal intervals in one row. In each row, n magnetic sensor chips corresponding to the m-th counted from the lowermost chip constitute one set. The combinations of magnetic sensor chips (magnetic sensor chip sets) in FIG. 4 are 12 sets of MR1 and MR2, MR3 and MR4 to MR21 and MR22, and MR23 and MR24.

  In FIG. 4, the distance (for example, the distance from the center of MR1 to the center of MR3) between two adjacent magnetic sensor chips (for example, MR1 and MR3) on one surface of the substrate is 2.5 mm. Further, when the distance between the magnetic sensor chip on the back side of the substrate and the adjacent magnetic sensor chip on the front side is 1.0 mm (the distance between MR3 and MR2) and 1.5 mm (the distance between MR2 and MR5) are alternated. It is arranged to be. Therefore, the distance (for example, the distance from the center of MR1 to the center of MR2) between two magnetic sensor chips (for example, MR1 and MR2) constituting one set shown in FIG. 4 is 3.5 mm.

The dimensions relating to the arrangement of the magnetic sensor chip as described above are determined according to the size and magnetic strength of the magnetic body to be used, and the size and average sensitivity of the magnetic sensor chip to be used. In other words, the above dimensions vary depending on the size and magnetic strength of the magnetic material and the size and sensitivity of the magnetic sensor chip.
Specifically, an average of 1.5 to 5 sets, preferably 2 to 4 sets, most preferably 2.5 to 3.5 sets (ideally 3 sets) in the range in which the magnetic body can move up and down. It is preferable to arrange the magnetic sensor chips so that the set of magnetic sensor chips (corresponding logic circuit) of () outputs a signal that magnetism is detected. The above dimensions can be determined by conducting preliminary experiments.

The magnetic sensor chip normally outputs an L level signal when magnetism is sensed and an H level signal when no magnetism is sensed. Of course, a magnetic sensor chip having an opposite relationship can also be used in the present invention.
The signals output from the magnetic sensor chips (MR1 to MR24) are processed by the logic circuit unit (5). When the magnetic sensor chip senses magnetism, the logic circuit unit (5) employs NOR gates (G0 to G11) when it outputs a signal at L level, and when it does not sense it, it outputs an H level signal. The NOR gate is a gate that outputs H only when all the magnetic sensor chips constituting each set output L, and outputs L otherwise (when any of them outputs H). As a result, H is output only when all the magnetic sensor chips constituting each set sense magnetism, and L is output when any of the magnetic sensor chips does not sense magnetism.

When a magnetic sensor chip senses magnetism, it outputs an H level signal. When it does not sense it, it outputs an L level signal. Instead of the NOR gate, an OR gate is used to form a magnetic sensor chip constituting each set. Only when all of them detect magnetism, H can be output, and when any one of the magnetic sensor chips does not detect magnetism, L can be output.
The present invention employs the gate as described above, so that a signal output from the magnetic sensor chip is detected only when the plurality of magnetic sensor chips constituting each set detect magnetism. Can be processed.

The signals (SW0 to SW11) output from the NOR gates (G0 to G11) are input to the determination unit (6), and it is determined from which level the liquid level is located.
The determination unit (6) shown in FIG. 4 includes a signal / serial conversion circuit (61), a microcontroller (63), and a D / A converter (65).

  A signal (SW0 to SW11) from the NOR gate is either H or L. The signal / serial conversion circuit (61) converts this signal into a serial data signal (62) so that it can be read by the microcontroller (63).

  In the microcontroller (63), what signal pattern appears in each level of the liquid level to be detected is recorded in advance. The signal pattern corresponding to each stage is subjected to a preliminary test after product manufacture (before sale), and the result is recorded in the microcontroller (63). As illustrated in each figure, when the liquid level is divided into 12 stages in order to detect the measurement range of 30 mm with an output accuracy of 2.5 mm, the preliminary is performed 12 times by changing the liquid level in units of 2.5 mm. Measurements and record the signal pattern for each case.

For example, liquid is put in the container so that the liquid level becomes 2.5 mm, preliminary measurement is performed, and patterns of 12 signals (SW0 to SW11) from the NOR gate (for example, in the order of SW0 to SW11, HHLLLLLLLLLLL) is recorded as a pattern when the liquid level is 2.5 mm.
Next, a liquid is added to the container so that the liquid level is 5.0 mm, and the same measurement is performed to obtain a signal pattern (for example, HHHLLLLLLLLL), which is a pattern when the liquid level is 5.0 mm. Record as.
By repeating the above measurement and recording (actually automatic processing is possible), 12 signal patterns corresponding to 12 levels of liquid level are obtained.

In actual measurement, when the obtained signal pattern coincides with a signal pattern corresponding to 12 levels of liquid level recorded in advance, it is determined that the level is that level.
The obtained signal pattern may be different from the signal pattern corresponding to the liquid level of 12 steps. In such a case, it can be disregarded as a transient liquid level in the middle of output accuracy. The method and apparatus of the present invention is suitable for continuously detecting a change in the liquid level in the container. For this reason, even if a signal pattern corresponding to a transient liquid level intermediate in output accuracy temporarily appears, it can be ignored without any problem.

  The numerical value of the liquid level determined by the microcontroller (63) is output as a digital signal (64). The digital signal (64) is output as an analog signal (66) by voltage from the D / A converter (65). In general, a high voltage is output when the liquid level is high, and a low voltage is output when the liquid level is low, with a voltage step (for example, 12 steps between 1V and 5V) corresponding to the number of measurement steps (eg, 12 steps). .

The apparatus of the present invention is preferably provided with a power line, a temperature output line, and a ground (GND) line in addition to the liquid level output line (66). These lines can be bundled to communicate with the outside of the device.
A display unit can be connected to the outside of the apparatus via a liquid level output line (66) and optionally a temperature output line. However, instead of providing the display unit or together with the display unit, the liquid level output line (66) may be directly connected to the liquid level adjusting means (liquid supply or discharge device) to automatically adjust the liquid level. Good.

The method and apparatus of the present invention allows the liquid level in the container to be detected very precisely (eg, with a liquid level output accuracy of 2.5 mm) using a relatively inexpensive magnetic sensor chip. became.
The method and apparatus of the present invention is particularly suitable for continuously detecting changes in liquid level in a container.

1 Float (magnetic float)
11 Magnetic body 2 Guide member 21 Stem (float guide cylinder)
22 Upper stopper 23 Lower stopper 3 Substrate (long substrate)
MR1 to MR24 Magnetic sensor chip 5 Logic circuit part (electric signal detection processing circuit)
G0-G11 NOR gate SW0-SW11 NOR gate output signal 6 Judgment part 61 Signal / serial conversion circuit 62 Serial signal 63 Microcontroller 64 Digital signal 65 D / A converter 66 Output by voltage 7 Attaching part 71 Nut 72 Screw thread 73 Volt 8 Container (liquid storage container)
81 Lid 82 Handle 9 Liquid 91 Liquid level

Claims (8)

A method for detecting a liquid level of a liquid stored in a liquid storage container having a liquid supply port and / or a liquid discharge port, the method including the following steps:
A liquid storage container having a liquid supply port and / or a liquid discharge port, a float guide cylinder vertically disposed inside the container, and outside or inside the guide cylinder so as to be able to move up and down along the guide cylinder Mounted magnetic float, long shape with at least 6 magnetic sensor chips arranged on the inside or outside of the guide cylinder in parallel with the guide cylinder and fixed at regular intervals in the vertical direction Providing a liquid storage device with a liquid level detecting device including a substrate and a liquid level detecting device including a magnetic signal detecting / processing circuit electrically connected to each of the magnetic sensor chips;
Storing the liquid in the container;
The step of detecting the level of the liquid level contained in the container by a method including the following operations and processes:
1) An operation for detecting the magnetic signal of the magnetic float moved on the surface of the liquid in the container by buoyancy by the magnetic sensor chip,
2) In the magnetic signal detection / processing circuit, the magnetic signal detected by each magnetic sensor chip is set as a unit of a magnetic sensor chip set composed of two or more magnetic sensor chips located in close proximity to each other, Only when all the magnetic sensor chips included in the unit have received a magnetic signal, a process for recognizing that the magnetic sensor chip set of the unit has received a magnetic signal from the magnetic float, and 3) Confirmed in advance Based on the relationship between the position of the unit of the magnetic sensor chip set and the liquid level, the liquid level is determined from the position of the unit of the magnetic sensor chip set that is recognized as having received the magnetic signal from the magnetic float in step 2). Processing to detect the level of.   2. The liquid level detection according to claim 1, wherein the magnetic float is a ring-shaped magnetic float mounted on the outside of the guide cylinder, and a long substrate having a magnetic sensor chip on the surface thereof is disposed inside the guide cylinder. Method.   3. The liquid level detection method according to claim 1, wherein the same number of magnetic sensor chips are provided on each of both side surfaces of the elongated substrate.   The liquid according to claim 3, wherein the magnetic sensor chip provided on one surface of the elongated substrate and the magnetic sensor chip provided on the other surface are arranged so that their heights are not the same. Surface level detection method.   The magnetic sensor chip set is composed of a chip corresponding to the nth from the lowest chip of the magnetic sensor chip provided on one surface and a chip corresponding to the nth from the magnetic sensor chip provided on the other surface. The liquid level detection method according to claim 3 or 4.   A liquid level detecting device for detecting a liquid level of a liquid stored in a liquid storage container having a liquid supply port and / or a liquid discharge port, which is vertically arranged inside the container. Float guide cylinder, magnetic float mounted on the outside or inside of the guide cylinder so that it can move up and down along the guide cylinder, on the inside or outside of the guide cylinder, arranged in parallel with the guide cylinder, etc. Liquid level detection including an elongated substrate having at least six magnetic sensor chips arranged and fixed at intervals on the surface, and a magnetic signal detection / processing circuit electrically connected to each of the magnetic sensor chips The same number of devices, however, magnetic sensor chips are provided on both side surfaces of the elongated substrate.   The liquid level detection according to claim 6, wherein the magnetic float is a ring-shaped magnetic float mounted on the outside of the guide cylinder, and a long substrate having a magnetic sensor chip on the surface thereof is disposed inside the guide cylinder. apparatus.   8. The magnetic sensor chip provided on one surface of the elongated substrate and the magnetic sensor chip provided on the other surface are arranged so that their heights are not the same. Liquid level detector.

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