JPH0520986Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a liquid level meter that measures the liquid level (liquid amount) in a tank.

``Prior Art'' Conventionally, a liquid level gauge has been common in which a float is attached to a guide rod hanging inside a tank so as to be movable up and down, and the height of the float is detected by various means.

``Problems that the invention attempts to solve'' Regarding the float type liquid level gauge as mentioned above,
It is necessary to create and maintain an environment in which the float can operate properly, it is necessary to clean the inside of the tank and perform maintenance and inspection of the instrument itself in a short period of time, and there is also the problem of high manufacturing costs.

``Means for Solving the Problems'' However, the present invention consists of laminating a pair of vertically long flexible resin sheets in a bag shape through a spacer, and forming a plurality of contact points at a constant pitch on the opposing inner surfaces of each sheet. a thermistor that supplements correction of the liquid level based on detection of a change in liquid temperature; The switch contacts that detect the upper and lower limits of the stored liquid level are printed.
The structure is such that nitrogen gas is sealed inside to prevent dew condensation.

``Function'' Therefore, since the instrument has a static structure that is not easily influenced by the surrounding environment, the period for cleaning the tank and maintenance and inspection of the instrument itself can be significantly extended. Since it has a simple structure, it can be manufactured at low cost, is superior in terms of handling and cost compared to conventional methods, and can measure the liquid level accurately, especially in this case, there is no possibility of misdetection of the liquid level due to temperature changes. Highly accurate liquid level detection is performed by preventing condensation from forming inside, and when the liquid level reaches its upper and lower limits, this is notified to the operator so that the liquid level can always be maintained within the appropriate range. Moreover, by using a chemically resistant sheet, this liquid level gauge can be effectively used for various purposes such as for chemical liquids.

"Embodiments" Examples of the present invention will be described below in detail based on the drawings. Figure 1 is a cross-sectional view of the liquid level measurement part, and Figure 2 is a cross-sectional view of the entire part.
It is a liquid tank having a cylindrical level gauge case 5 with a large number of liquid passage ports 4 on the circumference,
A threaded portion 5a at the upper end of the case 5 is screwed and fixed to the upper surface of the tank 1, so that the case 5 is suspended and supported from the upper surface of the tank 1 near the bottom surface.

Then, the membrane switch type liquid level gauge body 6
is installed inside the case 5. The main body 6 is the third
A pair of vertically elongated flexible resin sheets 7 and 8 shown in FIGS.
The main body 6 is fitted and supported by a frame 10 with a C-shaped end surface that is stretched inside the case 5, and one sheet 8 that contacts the main surface of the frame 10 is attached to the other sheet 7. It is configured to be brought into close contact using hydraulic pressure.

In addition, a strip-shaped thin film resistor 11 is printed on the center of the surface of the movable sheet 7 facing the fixed sheet 8 from the upper end to the lower end, with contact portions 11a projecting from the upper end to the lower end alternately on the left and right at a constant pitch. At the same time, a switch contact 12 for a liquid supply alarm is printed on the upper end of the surface of the sheet 7, and a switch contact 13 for a shortage alarm is printed on the lower end,
A pair of conductors 14a, 14b are electrically connected to the surface of the fixed-side sheet 8 facing the movable-side sheet 7 via the left and right contact portions 11a of the resistor 11.
and a pair of conductors 15a, 15b, 1 which are electrically connected to each other via the respective switch contacts 12, 13.
6a, 16b, and upper and lower thermistors 17, 18 for detecting the internal temperature of the main body 6 and their conductors 19, 20.
The upper ends of each conductor are connected to the liquid level control circuit via the printed connector 21, and the left and right contacts of the resistor 11 are connected to the conductors 14a and 14b in accordance with the contact length of each sheet 7 and 8. Part 1
1a... and each of the conductors 15a, 15b, 16
The switch contacts 12 and 13 are crimped onto the contacts a and 16b, respectively.

The present embodiment is configured as described above, and when the liquid A in the tank 1 increases, the liquid level gauge main body 6 is immersed in the liquid A sequentially from the lower end side, and one sheet 7 of the immersed portion is immersed in the liquid A. It comes into close contact with the other sheet 8 due to the pressure, and the left and right contact portions 11 on the lower side of the resistor 11
By sequentially crimping the conductors 14a and 14b starting from a, the resistance value between the conductors 14a and 14b is increased sequentially, and when the liquid A in the tank 1 decreases, the main body 6 is sequentially pressed onto the liquid from the upper end side. The exposed portion of one sheet 7 separates from the other sheet 8 due to the restoring force, and the resistor 1
Conductor 14 sequentially from upper left and right contact portions 11a of 1
By moving away from a and 14b, the conductor 1
The resistance value between 4a and 14b is sequentially decreased. In this way, the conductors 14a, 14 correspond to the increase or decrease of the liquid A.
By changing the resistance value between b, the contact upper end position of the sheets 7 and 8, that is, the liquid level, is calculated based on this resistance value via a liquid level control circuit.

Further, when the liquid A is supplied to the liquid storage upper limit position of the tank 1, the switch contact 12 is crimped to the conductors 15a, 15b, and the conductors 15a, 15b are
By electrically connecting the switch contact 13 to the conductor 1, when the liquid A decreases to the lower limit of liquid storage in the tank 1, the switch contact 13 is connected to the conductor 1.
By crimping the conductors 15a and 16b and electrically connecting the conductors 15a and 15b, a buzzer or lamp for warning of shortage, for example, is activated via a liquid level control circuit.

In addition, by turning on the switch contacts 12 and 13, electromagnetic valves for supplying and draining liquid may be controlled.

Furthermore, the resistance value between the conductors 14a and 14b is corrected based on the outputs of the thermistors 17 and 18 to prevent erroneous detection of the liquid level due to temperature changes.

Further, in this embodiment, the liquid level gauge main body 6 is disposed inside the case 5, but the main body 6 may be directly attached to the side wall of the tank 1.

"Effects of the Invention" As is clear from the above embodiments, the present invention is able to connect a pair of vertically long flexible resin sheets 7 and 8 with spacers 9 and 8.
A thin film resistor 11 having a plurality of contact portions 11a at a constant pitch on the opposing inner surfaces of each sheet 7 and 8 is electrically connected to the resistor 11 via the contact portions 11a. Along with printing a pair of liquid level detection conductors 14a and 14b,
Thermistors 17 and 18 that compensate for liquid level correction based on the detection of liquid temperature changes and switch contacts 12 and 13 that detect the upper and lower limits of the stored liquid level are printed, and nitrogen gas is filled inside to prevent condensation. Because it is sealed, it has a static instrument structure that is not easily influenced by the surrounding environment, and the period for cleaning the tank and maintenance and inspection of the instrument itself can be significantly extended.In addition, simply bringing a pair of sheets into contact with each other using hydraulic pressure Because of its simple structure, it can be manufactured at low cost, is superior in terms of handling and cost compared to conventional methods, and can accurately measure the liquid level. It is possible to prevent condensation from forming on the surface of the liquid and perform highly accurate liquid level detection, as well as notify the operator when the liquid level reaches its upper and lower limits so that the liquid level can always be maintained within the appropriate range. Furthermore, by using a chemical-resistant sheet such as PET or PP material, this liquid level gauge can be used successfully for various purposes such as for chemical liquids.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a liquid level measuring part showing an embodiment of the present invention, Fig. 2 is a cross-sectional view of the whole, Figs.
The figure is a surface view of the flexible resin sheet, and FIG. 5 is a longitudinal sectional view of the main body of the liquid level meter. 7, 8... Flexible resin sheet, 9... Spacer.

Claims (1)

[Scope of utility model registration request] A pair of vertically long flexible resin sheets 7 and 8 are pasted together in a bag shape through a spacer 9, and a thin film resistor 11 has a plurality of contact portions 11a at a constant pitch on the opposing inner surfaces of each sheet 7 and 8; A pair of liquid level detection conductors 14a and 14b are printed and electrically connected to the resistor 11 via the contact portion 11a, and thermistors 17 and 18 are used to compensate for liquid level correction based on detection of liquid temperature changes. A liquid level gauge characterized in that switch contacts 12 and 13 for detecting the upper and lower limits of the stored liquid level are printed, and nitrogen gas for preventing dew condensation is sealed inside.