JPS60198442A - State detector for liquid or the like - Google Patents

Abstract

PURPOSE:To detect the state of a liquid such as a liquid level easily with high precision by utilizing >=2 thermistors having the same positive temperature characteristics and utilizing the potential difference which is generated between the positive characteristic thermistors according to temperature. CONSTITUTION:Positive characteristic thermistors P1 and P2 forming a detection part 3 are powered on by a power source part 1 through resistances R1 and R2 of a display part 2 to heat up. When the thermistors P1 and P2 are both dipped in a liquid O, there is no temperature difference between the both and their resistance values are nearly equal. Therefore, potentials at both terminals of a light emission diode D1 are nearly equal and there is no potential difference, so no current flows through the diode D1, which is off. If the liquid in a container 4 decreases until the thermistor P2 is exposed to air in said balanced state, the radiation state of the thermistor P2 is improved and the thermistor heats up to generate some temperature difference between both. Therefore, the diode D1 turns on owing to the current difference between the thermistors P1 and P2 and the level of the liquid is detected. Thus, the device which detects the state of the liquid easily with high precision is obtained.

Description

[Detailed Description of the Invention] The present invention... water vapor. The present invention relates to a liquid state detection device for detecting the type, mixing ratio, flow rate, flow rate, liquid level, liquid amount, etc. of liquids such as oil and liquefied liquid.

Conventional technology Conventionally, a positive characteristic thermistor is shown in FIG.

It is well known that the resistance exhibits a temperature characteristic in which the resistance suddenly changes around the Curie temperature. Devices that utilize this temperature characteristic to detect the level of liquid, etc. (for example,
8. Some Japanese special public works (1530-1983) have been put into practical use. These conventional devices d.

A current is passed through the positive temperature coefficient thermist, and the positive temperature coefficient thermistor comes into contact with a liquid, etc. while it is self-heating.

Knowledge 1 is displayed.

Such a device requires a processing circuit that measures the resistance change due to temperature change of the positive temperature coefficient thermistor, a display circuit that converts the measurement result into a liquid level, and displays the result.

It is necessary to use complex functional elements such as operational amplifiers. Therefore, the entire device is complicated and expensive, and also has a large number of functional elements, making it highly reliable.

It has a practical drawback of poor durability.

purpose of invention The present invention solves the problems of the conventional method.

1 j A device for detecting the state of liquid, etc., which effectively utilizes a semiconductor element that changes and a display means that operates in response to the change in resistance, and has an extremely simple configuration that does not use functional elements such as operational amplifiers. By doing so, it is an object of the present invention to provide a device for detecting the state of liquid, etc., which is simple and has excellent accuracy, reliability, durability, etc., which has not been seen before.

In other words, the present invention provides a display means by effectively utilizing the current difference between the semiconductor elements caused by the temperature difference between at least two or more semiconductor elements that are driven by a power source and whose resistance changes depending on their own temperature. It is an object of the present invention to provide a device that can be operated to accurately and simply detect the state of a liquid y@ in an extremely simple manner without using complicated functional elements. More specifically, the present invention uses a semiconductor element 9 driven by a source, for example, at least a positive temperature thermistor having equal temperature characteristics, and uses a temperature difference between the two (for example, one in air and the other in air). (If it is in a liquid, there will be a temperature difference between the positive temperature coefficient thermistors.) This creates a potential difference between the positive temperature coefficient thermistors, and this potential difference can be used as a display means to generate a light emitting device or a sounding body 9, such as a light emitting diode or a lamp. By making a buzzer or the like directly blink or sound to display the state of the liquid, for example, the liquid level, it is extremely easy to detect and efficiently detect the state of the liquid without using complex functional elements. The purpose is to provide an effective bite detection device.

Structure of the Invention The device for detecting the state of a liquid or the like according to the present invention includes a plurality of loads connected to a power source, a semiconductor element connected corresponding to the loads and whose resistance changes depending on its own temperature, and a semiconductor element connected to each of the loads and the semiconductor element. 9. Display means connected between the elements; The display device is configured to detect the state of the liquid, etc., which activates the display, based on a resistance change that occurs when one of the semiconductor elements undergoes a temperature change depending on the liquid, etc. to be measured.

Effects of the Invention---4-1 The present invention connects semiconductor elements that cause resistance changes depending on their own temperature to a power source via corresponding loads, and connects semiconductor elements between each load and the semiconductor elements. The display means is connected to the water to be measured, and the display means is directly actuated based on the resistance change that occurs when one of the semiconductor elements undergoes a temperature change depending on the liquid to be measured. This demonstrates the effect of being able to immediately, easily and accurately detect the type, mixing ratio, flow rate, flow rate, liquid level, liquid volume, etc. of liquids such as steam, oil, and liquefied gas.

Furthermore, the present invention provides a positive temperature coefficient thermistor in which the semiconductor element is a positive temperature coefficient thermistor that shows a drastic change in resistance depending on its own temperature, so that any one of the positive coefficient thermistors can undergo a temperature change depending on the liquid to be measured. This has the great effect of making it possible to implement a device for detecting the state of a liquid or the like with an extremely simple configuration without converting the large resistance change that occurs into a large voltage change.

Furthermore, the present invention relates to the arrangement of the semiconductor element.

It is only necessary that any one of the semiconductor elements be in a state that allows it to undergo temperature changes, and it is possible to arrange it in any desired arrangement such as vertical arrangement, horizontal arrangement, diagonal arrangement, etc., and its range of use is extremely wide. be effective.

If set at the right time, the liquid level will show extremely large changes.

For example, it has the great effect of being able to very easily detect the state of liquids such as water tanks and oil tanks.

Furthermore, in the present invention, the detection part can be implemented with a small and lightweight structure to fix the semiconductor element, and can be used as a means for detecting the VV of engine oil of automobiles, etc. This has an extremely large effect on improving vehicle safety.

Further, the present invention provides that the display means connected between the seven or more loads and the semiconductor resistor is a means that operates with a potential difference caused by a change in resistance due to a temperature change in any of the semiconductor elements. This has the great advantage of being able to use any sounding body, etc., and selecting the most suitable display means depending on the purpose of implementing the present invention.

Principle of Operation of the Invention The principle of operation of the apparatus for detecting a liquid or the like of the present invention will be explained below with reference to FIGS. 1, 2, and 3.

A semiconductor element such as a positive temperature coefficient thermistor has a temperature characteristic in which its resistance suddenly changes near its Curie temperature Tc.

Normally, when this positive temperature coefficient thermistor is used for the purpose of detecting the level of liquid, etc., a current is passed through the positive temperature coefficient thermistor from a power source to cause it to self-heat to its Curie temperature +1+c or higher. In the equilibrium state after heating, the temperature of the PTC thermistor itself remains constant, and its resistance also remains constant. When this positive temperature coefficient thermistor in an equilibrium state is brought into contact with a liquid or the like and rapidly cooled, the positive temperature coefficient thermistor 4)/M degrees decreases, and its resistance value exhibits a switch characteristic in which it rapidly decreases. This switching characteristic is converted into a voltage signal, etc. to determine the liquid level, and a custom-made switch based on the temperature of a positive characteristic thermistor as an example of an element is effectively used. The purpose is to create a temperature difference in the thermistor and display the resistance difference due to this temperature difference directly as a liquid level.

FIG. 2 shows an example of the temperature characteristics of a positive temperature coefficient thermistor that is effective for constructing the device for detecting the state of liquid or the like according to the present invention.

In detail, it is a positive characteristic thermistor with a size of 2-×2-fins×2-fins, and its Curie temperature Te is 120°C.It is self-heated by a 12V DC voltage source and heated as an example of a liquid. This is a measurement of the current value flowing through a positive temperature coefficient thermistor when it is immersed in oil. Oil Temperature This is used as a buff meter in areas where engine oil is used, such as in automobiles.

8-- From Figure 2, the current difference between the positive temperature thermistor in oil A and in air is approximately 30 to 4 QmA at oil temperatures of -60°C to +80°C.
When setting the Curie temperature of a positive temperature coefficient thermistor to 120°C or higher, the difference in current between the oil and the air (30 to 40 n)
The oil temperature range within which lA) can be maintained can be further improved.

In order to utilize this characteristic as a state detection device for liquids, etc., it is necessary to effectively utilize the difference in current between the oil and the air. This current difference of about 30 to 40 mA is a current value that can sufficiently drive display means such as one light emitting diode.

Embodiment FIG. 6 shows the basic structure and operation of the device for detecting the state of liquid, etc. of the present invention, and this is considered as a first embodiment of the device of the present invention.

The liquid level detector of the first embodiment is composed of a power source 1, a display section 2, and a detection section 3.

When the liquid level detector of the first embodiment is used in an automobile, nine power sources 1 may be used, such as a battery.

The display section 2 includes resistors R4 and Rz, and a light emitting diode 1! D.

The resistors R+ and Rz have the same resistance value. One end of the resistors R1 and R is connected to the power supply I, and the other ends of the resistors R1 and R7 are respectively connected to a detection section to be described later. It is further connected to the positive characteristic thermistors P1 and P2 of the resistor R1 and the positive characteristic thermistor P.

A light emitting diode D1 is connected between the connection point of the resistor R2 and the positive temperature coefficient thermistor P2.

The detection unit 6 consists of positive temperature coefficient thermistors PI and P2 having the same temperature characteristics, and is immersed in the liquid θ in the container 4.

In this configuration and connection, the positive temperature coefficient thermistors P1 and P2, which constitute the detection section 3, are driven and self-heated from the power supply section 1 via the resistor R8 and the display section 2.

Since the positive temperature coefficient thermistors P1 and P are both immersed in the liquid 0, there is no temperature difference between them, and their resistance values are almost the same.

Therefore, a current iI flows from the power supply 1 to the PTC thermistor P through the resistor R5, and a current 12 flows from the power supply 1 to the PTC thermistor P2 through the resistor R2.
are almost equal, and there is no difference in current between the two.

Therefore, the voltages across each light emitting diode lh are the same, there is no potential difference, and no current flows through the nuclear light emitting diode D, which is turned off.

From this equilibrium state, the liquid O in the container 4 decreases.

When the positive temperature coefficient thermistor P2 is exposed to the air, the heat dissipation condition of the positive temperature coefficient thermistor P2 is not good, and it is heated even more, resulting in a temperature difference between the two. In other words, as shown in Fig. 2, the positive characteristic thermistor P1 is in oil + Pffi is in air.
1 is approximately 60mA Current flowing through IP2 12 is approximately 20mA
becomes. Therefore, this current difference (L-i,) of about 40 mA causes a voltage difference across the 9 light emitting diodes D10, and the current difference of about 40 mA flows through the light emitting diode D1.
The light emitting diode D1 lights up.

Therefore, the lighting of the light emitting diode D, 9 indicates that the PTC thermistor P is in the air, and whether the PTC thermistor P2 is in the liquid or in the air ---11--
− The level of the liquid can be detected depending on the presence of the liquid. In addition.

In addition to this, the display means can be directly applied to a piezoelectric buzzer or the like, or the light emitting diode and piezoelectric buzzer may be used in combination.d A preferred embodiment of the detection section B of the liquid level detector consisting of the above configuration and operation. are shown in FIGS. 4 and 5. ・The detection part 3 is the jig 3.
0, a positive characteristic thermistor P, and a positive characteristic thermistor P2, and lead wires 31, 34, and 35 of the positive characteristic thermistor Pt and P2.

In such a configuration, positive temperature coefficient thermistors P and P
, are arranged by providing mounting holes 31 and 32 in a part of the jig 30, respectively.

According to this configuration, the positive characteristic thermistors P1 and P
It is now possible to directly attach the elements No. 2 without molding, and the time constants of the switching characteristics of the positive temperature coefficient thermistors P1 and P can be used without damaging them. Furthermore,
Since it can be disposed within the shield A3[1, it serves to protect P and P from damage without coming into contact with external objects.

Also, lead wires 35 and 34 of positive characteristic thermistors P+ and Pg.
゜-, -12- 35 is fixed in the jig 30 with wire-proof molding material,
While preventing the inflow of liquid, the lead wire is fixed and led out by an external edge (decouper 38).

Further, by providing a mounting screw 37 at the upper end of the jig 30, the liquid level detection section 3 can be mounted to an oil pan or a radiator of an automobile or the like.

The liquid level detector according to the first embodiment of the present invention shown in FIGS. 2 and 3 does not use functional elements such as operational amplifiers, but simply connects seven or more positive temperature coefficient thermistors having the same temperature characteristics. Drive through.

It is possible to provide an extremely simple liquid level detector that can directly light a light emitting diode using the current generated by the temperature difference between the individual positive temperature coefficient thermistors.

In FIG. 3, a positive characteristic thermistor P1. The display was made to light up when both Pt and Pt were in the liquid, but if the positive characteristic thermistor P1 was in the liquid, P,
The initial setting may be such that the light emitting diode D1 is turned on when the liquid is in the air, and when the liquid level is lowered and the positive temperature coefficient thermistor P1 touches the air, the light emitting diode D is turned off.

It is desirable to do so.

Next, a second preferred embodiment of the present invention is shown in FIG.

Components that are the same as those in the first embodiment shown in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 6, a second embodiment of the present invention is comprised of a power supply section 1, a display section 2, and a detection section 3.

The display section 2 has resistors R,, R, having the same resistance value.

It consists of R1 and light emitting diodes D, ,D. The detection unit 3 includes positive temperature coefficient thermistors P, , P having the same temperature characteristics and arranged to face the liquid substance 0 in the container 4.
1 and a positive characteristic thermistor P, which is always placed in the air.

Further, one end of the resistors R1, ILz, and ns are connected to the power supply 1, and the other end of each of the resistors R1, ILz, and ns is connected to a positive characteristic thermistor P.
Connected to l, Px, and Ps. Furthermore, a resistor R1, a positive characteristic thermistor P r , Rx and P2 . Rs and P,
Light emitting diodes D, , D, are connected between the connection points.

When the light-emitting diode D2 is set to blue in a long-lasting configuration and the light-emitting diode D1 is set to red, when the positive temperature coefficient thermistor P and P2 are immersed in the liquid, Pl and P Since there is no temperature difference between , 1 light emitting diode D, does not light up. However, since the positive thermistor P, is always placed in the air, +P2 and P3
A temperature difference occurs between them.

The light emitting diode D lights up in blue.

The liquid level is good when the light emitting diode D lights up in blue. From this state, the liquid level in the container 4 decreases, and when the positive temperature thermistor P2 escapes from the liquid into the air, the positive temperature thermistor P The temperature difference between , and h disappears, and 9 light-emitting diode D
2 goes out.

However, since the positive temperature coefficient thermistor P1 is immersed in the liquid, a temperature difference occurs between +P1 and P2, and the light emitting diode D9 lights up in red. Therefore, if the judgment level μ of the liquid level is set at the position of the positive characteristic thermistor P.

--15 The light emitting diodes D1 and D1 are lit alternately depending on whether P2 is in the liquid or in the air, making it possible to display the liquid level very easily.

As described above, by using one PTC thermistor with the same temperature characteristics, the difference between the PTC thermistors can be adjusted depending on whether the PTC thermistor is in air or in liquid. Since a temperature difference occurs between the two, the resistance value of the positive temperature coefficient thermistor itself changes due to this temperature difference. Therefore, this reduction in resistance is converted into a change in the voltage supplied from the t source 1, and a potential difference is generated in the positive temperature coefficient thermistor system.

This potential difference lights one light emitting diode.

Therefore, the liquid level can be controlled using an extremely simple configuration in which one light-emitting diode can be turned on and off by simply using resistance based on the temperature difference between seven positive temperature coefficient thermistors without using a functional device such as an operational amplifier. It is possible to provide a detector.

Next, a third embodiment of the present invention will be explained based on FIG.

-16 This embodiment further expands on the first and second embodiments and has a configuration in which liquid levels at multiple points are detected.

Power supply section 1. ! :Resistance fL1〃・raR having the same resistance value
The display section 2 includes a display section 2 made up of light-emitting diodes D1 to Dn, and a detection section 3 made up of positive temperature coefficient thermistors P1 to Pn having the same temperature characteristics.

In such a configuration, the resistor 9 and the light emitting diode.

The relationship of the positive temperature coefficient thermistor is similar to that of the first embodiment.

As in the second embodiment, only the deep legs and k are connected in multiple stages.

In a liquid level detector consisting of the above configuration and connections.

If the initial setting is such that all of the positive temperature coefficient thermistors P1 to Pn are immersed in the liquid O in the container 4, then for example, when the upper part of the positive temperature coefficient thermistor P6 escapes into the air, the positive temperature coefficient thermistors P, - A temperature difference will occur only between P6 and P6, and at this time, the temperature difference between P5 and Pl will change the resistance value of itself by -1, that is, the resistance of P6 in the air or the resistance of P in the liquid. It becomes larger than . Therefore, resistance B-
The voltage at the connection point between and the positive characteristic thermistor P6 is the resistance hole,
and positive characteristic thermistor →.

As a result, a potential difference occurs between the two ends of the light emitting diodes D connected between the respective connection points, and the light emitting diodes D9 light up.

From the above operation, the positive characteristic thermistor P,
If ~Pn is arranged and the liquid level is displayed using the light emitting diodes D and ~Dn in correspondence with the respective positions, large changes in the liquid level can be detected very easily.

Furthermore, if the light emitting diodes D, -Dn are displayed as a bar graph, it becomes possible to display the liquid level in an approximate manner to an analog quantity.

In summary, the following is a summary of the implementation of the present embodiment device.

Has equivalent temperature characteristics. The resistors of more than one positive characteristic thermistor, each with the same resistance value, are self-heated. In this state, if one of them is in liquid or air, and a temperature difference occurs between the seven positive temperature coefficient thermistors, a difference will occur in the resistance value of the large body. Therefore, a potential difference is generated between the resistor terminals due to this change in resistance, so if a light emitting diode is connected between the contact point of the resistor and the positive temperature coefficient thermistor, the light emitting diode can be lit by the potential difference.

Therefore, a light emitting diode can be lit depending on whether one of the positive temperature coefficient thermists is in liquid or air.

The liquid level can be detected and displayed by lighting the light emitting diode.

Results 9 The device for detecting the state of liquid, etc. of the present invention can detect and display the liquid level using only a positive temperature coefficient thermistor, a resistor, and a light emitting diode, without using functional elements such as operational amplifiers or transistors, and is extremely easy to operate and display. It is possible to provide a liquid level detector that is highly effective as an on-vehicle sensor for automobiles, etc.

In the above invention, the display unit 2 was implemented by lighting 9 light emitting diodes, but by driving a relay element such as a reed relay, the contacts of the relay can be set to 0N-OFF, and other lamp displays can be displayed on the relay contacts. May be connected. Furthermore, although the detection section 3 utilized the temperature-dependent switching characteristics of a positive temperature coefficient thermistor, the detection section consists of at least one element, and the resistance changes depending on whether the element is in liquid or air. -19- Elements with similar functions (e.g. negative characteristic thermistors)
If so, it can be used effectively.

Furthermore, the device for detecting the state of liquid, etc. of the present invention has been described as a device for detecting the liquid level of engine oil as a preferred embodiment thereof. Any atmosphere that can be formed is sufficient. That is, it is only necessary that there be a difference in the thermal conductivity of the surrounding air of the semiconductor element. For example, in the case of the same liquid, this difference in thermal conductivity can be detected as a difference in viscosity, and can also be applied to a viscosity detection means.

Furthermore, gases such as Freon Ganu, which are easily vaporized in the air, can be detected, and the device can also be used as a Ganu detector.

Further, if one of the semiconductor elements is placed in a stationary liquid and the other in a path in which the liquid moves, it becomes possible to detect the movement of the liquid, that is, the velocity and flow rate of the fluid.

Furthermore, by arranging one of the semiconductor elements in the standard 1:1.4 surroundings of the object to be measured and placing the other in the object to be measured, the aspect 1 in the object, for example in a liquid, can be It is possible to detect the generation of bubbles and emulsification in liquids, and it is also possible to detect the generation of paper and mist in gases with great ease.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the switching characteristics of a positive temperature coefficient thermistor, Figure 2 is a diagram showing an example of the 1M degree characteristic of a positive coefficient thermistor in air and oil, and Figure 3 is a diagram showing the first embodiment. A schematic diagram showing the apparatus, FIGS. 4 and 5, is shown in FIG. 15i!
A front view and a cross-sectional view showing the specific structure of the detection section of the embodiment, FIG. 6 is a schematic diagram showing the device of the second embodiment, and FIG. 7 is a 35th!
FIG. 1 is a schematic diagram showing an example device. Ord-P+, Pz...Positive Thermistor Patent Applicant Toyota Central Research Institute Co., Ltd. (1 other person) 7th 10. 4 Ri70 Q Near 0 Cow 0 Figure 6 JP-A-Sho GO-198442 (8) Kore 7 Ko "'pn"V'2

Claims (6)

[Claims] (1) A plurality of loads connected to a power source, a semiconductor element connected correspondingly to the load and whose resistance changes depending on its own temperature, and a display means connected between each of the loads and the semiconductor element. The liquid is characterized in that the display means is actuated to detect the state of the liquid, etc. based on a resistance change caused when one of the semiconductor elements undergoes a temperature change depending on the liquid, etc. to be measured. etc. status detection device. (2) The device for detecting the state of a liquid or the like as set forth in item (1) of the patent, wherein the semiconductor element is a thermistor having positive temperature characteristics. (3) The device for detecting the state of a liquid or the like as set forth in claim (1), wherein the semiconductor element is a thermistor having the same or the same temperature characteristics. (4) Either one of the semiconductor elements converts a change in resistance due to a change in temperature into a change in voltage using a power source and a load, applies a potential difference to the display means, operates the display means, and detects the state of the liquid, etc. SK, which is characterized by
A device for detecting the state of a liquid, etc., according to claim (1). (5) The device for detecting the state of a liquid or the like as set forth in claim (1), wherein the display means is a light emitting device that displays light by emitting light generated by a current based on the potential difference. (6) The device for detecting the state of liquid or the like as set forth in claim (1), wherein the display means is a sounding body that displays sound produced by the potential difference.