KR20020095802A - Device for sensing liquid level - Google Patents

Abstract

PURPOSE: An optical type liquid level sensing device is provided to achieve improved accuracy of liquid level measurement by eliminating the necessity of performing temperature compensation for the signal output from the sensor unit. CONSTITUTION: An optical type liquid level sensing device(12) comprises a liquid inlet tube(18) having, at a bottom thereof, a hole for introduction of oil; an operator side cavity(27) including the space formed in the liquid inlet tube; an operator side piston(46) moving in accordance with the pressure of the gas contained in the operator side cavity, wherein the pressure of the gas changes in accordance with the amount of liquid introduced into the liquid inlet tube; a temperature compensator side cavity(28) for containing gas for temperature compensation; a temperature compensator side piston(50) moving in accordance with the pressure of the gas contained in the temperature compensator side cavity; a sensor unit(24) connected to one of the operator side piston and the temperature compensator side piston, which includes a light emitting element and a light receiving element which are opposed with each other; and a shut-off screen connected to the other of the operator side piston and the temperature compensator side piston and connected between the light emitting element and the light receiving element.

Description

Optical liquid level sensing device {DEVICE FOR SENSING LIQUID LEVEL}

The present invention relates to a stored liquid volume or liquid level sensing device, and to an apparatus for sensing the height or volume of a liquid stored in an oil tank or a water tank.

Sensors are used to measure the liquid level in oil tanks or baths. One conventional liquid level sensing device is described in Korean Patent Publication No. 96-13254. The sensing device includes an air inlet, a flat rubber membrane, a light emitting and receiving element installed in the upper case, and a reflecting plate installed in the rubber membrane. As the water level rises, the pressure of the air entering the air inlet increases, which deforms the reflector. The deformation of the reflector causes a change in distance between the optical element and the reflector. The distance change is converted into an electrical signal change in the optical device and transmitted to the outside.

The sensing device of the above structure is difficult to cope with a storage tank having a large change range of liquid level, that is, a deep depth. The electrical signal is also easy to change in response to external temperature changes. In addition, the conventional liquid level sensing device only outputs the output related to the liquid level of the stored liquid, and cannot output the output proportional to the stored flow rate.

It is an object of the present invention to provide a sensing device for sensing the volume of a stored liquid.

Another object of the present invention is to provide a sensing device that can be applied to a storage tank having a large change in liquid level.

The present invention has been made in an effort to provide a sensing device capable of uniformly outputting a signal corresponding to an actual liquid level even when there is a change in temperature of outside air, that is, temperature compensation.

Still another object of the present invention is to provide a sensing device that minimizes the influence of the weight of the components.

1 is a cross-sectional view of an oil tank equipped with a sensing device according to an embodiment of the present invention.

2 is a cross-sectional view of the sensing device of FIG.

3 is a side view of the sensing device of FIG.

FIG. 4 is an exploded perspective view of the sensing device of FIG. 1, showing only some components; FIG.

Figure 5a is a cross-sectional view showing a lower portion of the tube of the sensing device of Figure 1 and Figure 5b is a side view

6 is a cross-sectional view showing the connection of the connecting rod of the sensing device of FIG.

7 is a detailed view illustrating a sensor unit of the sensing device of FIG.

8 is a circuit diagram of a light emitting device of the sensing device of FIG.

9 is a perspective view showing an oil tank to which another embodiment of the present invention is applied;

10 is a front view and a cross-sectional view of a light receiving element of a sensor unit provided in the sensing device applied to the tank of FIG.

11 is a view of a light emitting device provided in the sensing device applied to the tank of FIG.

According to one aspect of the invention, the device for sensing the volume or liquid level of the liquid stored in the reservoir,

A liquid inlet pipe inserted into the reservoir and provided with a hole in the lower end to allow liquid to flow from the lower end;

An operation side gas chamber including a space in the liquid inlet pipe,

An operation side piston moving according to the pressure of the gas in the operation side gas chamber, which changes according to the amount of liquid introduced into the liquid inlet pipe;

A temperature compensation side gas chamber in which gas for temperature compensation is accommodated;

A temperature compensation side piston moving according to the pressure of the temperature compensation side gas chamber,

A sensor unit connected to one of the operation side piston and the temperature compensation side piston, the sensor unit including a light emitting element and a light receiving element facing each other;

It is connected to the other of the operating side piston and the temperature compensation side piston, and includes a blocking film connected between the light emitting element and the light receiving element,

A sensing device having the same volume of the working side gas chamber and the temperature compensation side gas chamber is provided.

In a preferred embodiment the sensing device comprises a first case having a cavity forming part of the working side gas chamber,

A second case having a cavity for forming at least a part of the temperature compensation side gas chamber;

A temperature compensating tube connected to the cavity forming a temperature compensation side gas chamber,

It further comprises a deformable diaphragm blocking said respective cavity. Each piston is connected to a diaphragm that blocks each corresponding cavity.

In a preferred embodiment, the first case and the second case are an integral cavity forming case. In a preferred embodiment, there is provided a support coupled to the first case and the second case, the support being provided with a bushing, the movement of the piston being guided by the bushing.

The piston has a plate attached to the end in contact with the diaphragm, the elastic member is sandwiched between the bushing and the plate is configured to adjust the distance between the bushing and the plate. The barrier layer is configured to move the barrier layer to enable initial positioning of the barrier layer.

The liquid inlet tube and the temperature compensating tube are disposed side by side, and each end of the tube has an enlarged portion having an enlarged inner diameter. The lower end of the liquid inlet pipe is blocked, and a liquid inlet hole is formed in the side wall near the lower end. The sidewall of the liquid inlet pipe is provided with a cover covering the liquid inlet hole and spaced apart from the sidewall. A valve is provided at the end of the temperature compensation tube.

The light receiving element is provided with a padding plate provided with a hole having a shape corresponding to the cross sectional area of the tank in front of the light receiving cell. The light receiving element includes a solar cell.

According to another aspect of the invention, an apparatus for sensing the volume or liquid level of a liquid stored in a reservoir,

A liquid inlet pipe inserted into the reservoir and provided with a hole in the lower end to allow liquid to flow from the lower end;

A case member forming a cavity connected to the liquid inlet pipe so as to form a gas chamber including a space in the liquid inlet pipe;

A piston positioned under the cavity, the piston being moved according to the pressure of the gas in the working side gas chamber, which changes according to the amount of liquid introduced into the liquid inlet pipe;

A sensor unit having a light emitting element and a light receiving element facing each other;

It includes a blocking film connected between the light emitting device and the light receiving device,

One of the blocking membrane and the sensor unit is provided with a sensing device connected to the piston.

According to another aspect of the invention, an apparatus for sensing the volume or liquid level of a liquid stored in a reservoir,

A liquid inlet pipe inserted into the reservoir and provided with a hole in the lower end to allow liquid to flow from the lower end;

A case member forming a cavity connected to the liquid inlet pipe so as to form a gas chamber including a space in the liquid inlet pipe;

A piston moving according to the pressure of the gas in the working side gas chamber, which changes according to the amount of liquid introduced into the liquid inlet pipe,

A sensor unit having a light emitting element and a light receiving element facing each other;

It includes a blocking film connected between the light emitting device and the light receiving device,

One of the blocking membrane and the sensor unit is connected to the piston,

At least one of the light receiving element and the light emitting element has a padding plate having a hole located on the side facing the blocking film, the distance from one end of the moving direction of the blocking film in the hole (hereinafter referred to as “moving distance”) And a ratio of the width in the direction perpendicular to the movement direction of the barrier membrane is substantially equal to the ratio of the height of the tank corresponding to the movement direction distance to the cross sectional area of the tank at that height.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification, but described as to measure the amount of oil in the oil tank as a preferred embodiment, the present invention is not limited thereto.

Referring to FIG. 1, the sensing device 12 is installed in the oil tank 10. The sensing device 12 is enclosed in the cavity forming case 14 and the housing 26. The case 14 is connected to the temperature compensating tube 17 and the liquid inlet tube 18. The temperature compensating tube 17 and the liquid inlet tube 18 extend to the bottom of the oil tank 10.

2 to 4, the sensing device 12 includes a cavity forming case 14, a driving unit supporting case 16, and a diaphragm 20 having a flexible elasticity sandwiched therebetween. The sensing device 12 includes a drive mechanism 22 and a sensor portion 24. The housing 26 covers the driving unit support case 16, the driving mechanism 22, and the sensor unit 24.

2 and 4, the cavity forming case 14 is formed with an operating side cavity 27 and a temperature compensation side cavity 28. These cavities 26 and 28 are formed in a generally cylindrical shape. Pipes 30 are drilled in the upper walls of the cavities 26 and 28. The cavity forming case 14 has a flange 32 at the inlet side of the cavity 26, 28.

2 and 4, the drive support case 16 has a shape that is generally similar to the cavity forming case 14. The drive part support case 16 is provided with the groove | channel 34 corresponding to each cavity 26 and 28 of the said cavity formation case 14, The component of the drive mechanism 22 in the space which this groove | channel 34 forms is formed. Are installed.

Holes 36 are drilled in the bottoms of the grooves 34, and female holes are formed in the holes 36. Bushings 38 and 54 are fitted into this hole 36. Male threads are formed on the outer circumferential surfaces of the bushings 38 and 54. As the bushings 38 and 54 are turned, the bushings 38 and 54 move up and down. The drive support case 16 has a flange 40 on the inlet side of the groove 34.

2 and 4, the diaphragm 20 has an edge 42, a bend 44, and a flat central portion 45. In assembly, the rim 42 is sandwiched between each of the flanges 32, 40 of the cavity forming case 14 and the support case 16. The diaphragm 20 is also fixed by coupling between the flanges 32 and 40 using an appropriate fastening method (nuts and bolts, rivets, welding, seaming or bonding, etc.). The bent portion 44 is formed around the circumferential direction, the side close to the rim is convex upward, the center side is made of a convex downward. However, the present invention is not limited only to this configuration. The configuration of the bent portion 44 of the diaphragm 20 may be different. The diaphragm 20 may be made of a synthetic rubber material, or may be made of an elastic plastic resin material.

Referring to Fig. 2, the drive mechanism 22 has an operating side piston 46. The distal end plate 48 of the operating side piston 46 pushes the central portion 45 of the diaphragm 20. The actuating side piston 46 extends through the longitudinally drilled guide hole of the bushing 38. An elastic member 48, such as a compression coil spring, is fitted between the bushing 38 and the leading disc 48. The elastic member 49 pushes the piston 46 toward the diaphragm 20.

The drive mechanism 22 has a temperature compensation side piston 50. Except for the rear end of the piston 50, since the same configuration as the operating side piston 46, the detailed description thereof will be omitted. Since the structure of the elastic member 52 which pushes the piston 50, and the structure of the bushing 54 are also the same as that of the operation side piston 46, detailed description is abbreviate | omitted.

The connecting table 56 is coupled to the rear end of the operating side piston 46. The connecting table 56 extends to the temperature compensation side piston 50. The blocking film 58 is fixed to the end of the connecting table 56. The sensor portion 24 is fixed to the rear end of the temperature compensation side piston 50.

The housing 26 covers the drive mechanism 22 and the support case. The housing 26 and the support case 16 are preferably provided with air flow holes.

1, 2, 3, 5a, and 5b, the temperature compensating tube 17 and the liquid inlet tube 18 are connected to the temperature compensating side cavity 28 and the operating side cavity 27, respectively. It protrudes upward and extends downward, and extends downward (see Fig. 3). These tubes 16 and 18 are collected from behind and inserted into the oil tank 10 and extend to near the bottom.

1 and 5A, the ends of these tubes 16, 18 are extended. This is to minimize the effect of surface tensions that may occur between the oil stored in the tank (other liquids in other embodiments) and the pipe wall.

A stopper 62 is provided at the end of the extension 61 of the temperature compensating tube 17. The stopper 62 is provided with a male screw, and the expansion portion 61 is provided with a female screw. Between the stopper 62 and the end of the extension 61 is provided an O-ring 64 for sealing. This stopper closes the tube just before the tank 10 is inserted. Then, the air pressure before insertion of the temperature compensating tube 17 and the liquid inlet tube 18 becomes equal. It is preferable that the temperature compensating tube 17 and the liquid inflow tube 18 have the same length.

The bottom end of the extension 66 of the liquid inlet tube 18 is blocked. The side wall near the bottom is provided with a liquid inlet 68 through which liquid can enter. Since the liquid inlet 68 is installed at the side wall, the fluid may enter even when the liquid inlet tube 18 touches the bottom of the tank 10. Near the liquid inlet 68, a cover 70 is provided away from the side wall of the extension 66 to create a gap through which the side wall of the extension 66 and the fluid can pass. The cover 70 reduces the influence of the liquid level in the expansion 66 even if there is a shake of the oil in the tank.

1 and 2, the volume of the working side air chamber formed by the liquid inlet pipe 18 and the cavity 27 and the temperature compensating side air chamber formed by the temperature compensating tube 17 and the cavity 28. The volume should be the same. The greater the difference, the greater the error due to temperature. To this end, in the embodiment of Fig. 1, the volumes of the cavities 27 and 28 are equal. In addition, the thickness and length of the tubes 16 and 18 are also the same. Then, the volume can be easily equalized.

Referring to Fig. 6, the end portion of the actuating piston 46 is provided with a small diameter projection 72. The protrusions 72 are provided with grooves 74 and female threads are formed therein. The connecting table 56 is provided with a boss 78 having a through hole 76. The jaw 80 is provided at the end of the through hole 76. The hole 76 of the boss 78 is fitted into the projection 72. An elastic member 82 such as a coil compression spring is positioned between the end of the protrusion 72 and the jaw 80. The screw 84 is inserted from the outside of the jaw 80. Tightening the screw 84 brings the connecting rod 56 close to the actuating side piston 46. When the screw is loosened, the elastic member 82 pushes out the connecting table 56. This can adjust the position of the connecting table 56. The side wall of the boss 78 is provided with a fixing screw 86 capable of radially advancing or retracting. After aligning the connecting table 56, the fixing table 56 is fixed so that the connecting table 56 does not move.

Referring to FIG. 7, the sensor unit 24 includes a support 88. The support 88 has a support 90 facing side by side. A groove is dug in the inner side of the facing surface, and the light emitting element 92 and the light receiving element 94 are fitted into and fixed to the groove. The blocking film 58 described above is sandwiched in the gap between the light receiving element 94 and the light emitting element 92. The light receiving element 94 may use a device that is commonly used. For example, a CdS cell may be used, and it is preferable to use a solar cell having excellent resolution. The gap between the light receiving element and the blocking film and the gap between the light emitting device and the blocking film may be minimized to a degree that permits movement. Referring to Figure 2, a wire is connected to the light receiving element and the light emitting element. A light emitting diode, which will be described later, emits light by supplying power to the light emitting element through the wire. Through a wire connected to the light receiving element, an output (voltage or current) corresponding to the light receiving amount is transmitted to the outside, and the physical level can be processed to detect the liquid level. The amount is then processed by an output signal processing device (not shown) and displayed for human viewing.

Referring to Fig. 8, the structure of a light emitting element 92 using a plurality of light emitting diodes is shown as an example. The light emitting device 92 includes a plurality of light emitting diodes 96 and a plurality of resistors 98 connected in series to each light emitting diode. The light emitting diodes are connected in parallel in a line. The resistance values may be the same, but it is better to increase the resistance at the center and the resistance at both ends. As for the light emitting diode, it is good to use the one without a reflector so that the light does not shade.

Hereinafter, the operation of the sensing device 12 according to the embodiment will be described.

As shown in Fig. 1, when the tube 18 is placed in the tank 10, as shown in Fig. 5A, liquid flows into the tube. Accordingly, the pressure of the air in the first operating side air chamber is increased. This pressure pushes the piston 46. When the piston 46 moves, the blocking film between the light emitting element 92 and the light receiving element 94 moves. The blocking film 58 partially opens between the light emitting device and the light receiving device, and the light receiving device sends an output corresponding to the amount of light received to the outside.

If the temperature of the outside air is high, the pressure in the operating side air chamber is increased to push up the piston 46. At this time, the pressure in the temperature compensating tube and the temperature compensating side air chamber is also increased to push up the piston 50 by the same amount as the piston 46. This is because the amount of air in the two spaces is about the same. Accordingly, even if the external temperature changes, the output from the sensor unit to the outside can maintain the same condition.

Referring to Figure 9, there is shown another type of oil tank 110. The tank 110, which is provided with the support 112, has a longitudinal cross-sectional shape. The sensing device of the present invention can also be applied to such an oil tank 110. At this time, the sensing device used uses the light receiving element 114 and the light emitting element 116 shown in Figs. 10A, 10B and 11.

10A and 10B, the light receiving element 114 includes a light receiving cell 118 and a padding plate 120. The patch plate 120 is formed with a hole having the same shape as the longitudinal section of the tank 110. Referring to FIG. 11, a plurality of light emitting diodes 124 are disposed on a circuit board 122 in the light emitting device 116. A copper thin film (copper foil) circuit line for supplying electricity to the plurality of light emitting diodes 124 is provided on the back side of the circuit board 122. It will be readily understood by those skilled in the art that such an arrangement of copper foil circuit lines is possible. As the light emitting device, a generally known surface light source may be used in addition to the circuit board using the light emitting diode.

With the above configuration, not only the liquid level but also the output corresponding to the volume of the stored liquid can be obtained. The tank in this embodiment has the same shape as the longitudinal section of the tank, since the longitudinal section shape is always kept constant. However, in the case of a tank (for example, a spherical tank) of a shape in which the longitudinal cross-sectional shape is not always kept constant, the shape of the hole must be formed differently. In this case, the ratio between the height of the tank and the cross sectional area of the tank and the height (up and down position) of the padding plate hole and the width of the hole may be formed to be substantially the same. In other words, when the bottom of the tank corresponds to one end of the up and down direction of the hole of the padding plate (exactly the moving direction of the barrier film), when the hole of the padding plate is formed, The ratio of the distance from one end to the transverse direction of the hole (preferably perpendicular to the direction of movement of the barrier) is matched to the ratio of the height from the bottom of the tank to the cross sectional area of the tank at that height. Then, even in the case of a spherical tank or a tank of various shapes, an output proportional to the storage flow rate can be obtained.

In the above embodiment the output from the sensing device is adapted to correspond to the volume of liquid stored in the tank. Alternatively, when the sensing device is configured to output an output corresponding to the height (ie, liquid level) of the liquid stored in the tank, the volume may have an external microprocessor calculate with the output corresponding to that level. It will be understood by those skilled in the art that the configuration of the microprocessor to receive the conversion of the liquid level output into a digital signal and calculate the volume thereof may be performed with reference to the description hereinabove. For this purpose, the relationship between the liquid level and volume for the tank may be stored in a nonvolatile RAM or ROM as a database.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto. Changes or modifications can be made to the above embodiments without departing from the spirit and scope of the invention, and those skilled in the art will understand that such changes or modifications are within the scope of the invention.

In the sensing device according to the present invention, there is no change in the signal from the sensor even if the internal air pressure changes with temperature. This is because temperature compensation is automatic. Therefore, it is not necessary to compensate for the temperature from the external electronic device with the signal from the sensor unit, so that the liquid level measurement can be accurately performed. Since the air chamber is located at the top, the possibility of measurement error due to the weight of various components of the sensing device is reduced. In addition, by using a surface light source and using a padding plate on the light receiving element, the sensing device can be used in any type of tank.

Claims (15)

A device for sensing the volume or level of liquid stored in a reservoir, A liquid inlet pipe inserted into the reservoir and provided with a hole in the lower end to allow liquid to flow from the lower end; An operation side gas chamber including a space in the liquid inlet pipe, An operation side piston moving according to the pressure of the gas in the operation side gas chamber, which changes according to the amount of liquid introduced into the liquid inlet pipe; A gas chamber on the temperature compensating side to accommodate gas for temperature compensation; A temperature compensation side piston moving according to the pressure of the temperature compensation side gas chamber, A sensor unit connected to any one of the operation side piston and the temperature compensation side piston and having a light emitting element and a light receiving element facing each other; It is connected to the other of the operating side piston and the temperature compensation side piston, and includes a blocking film connected between the light emitting element and the light receiving element, And a sensing device having the same volume as the operating gas chamber and the temperature compensating gas chamber. The method of claim 1, A first case having a cavity forming a part of the working side gas chamber, A second case having a cavity for forming at least a part of the temperature compensation side gas chamber; A temperature compensating tube connected to the cavity forming a gas compensating gas chamber; Further comprising a deformable diaphragm blocking said respective cavity, Wherein each piston is connected to a diaphragm blocking each corresponding cavity. The sensing device according to claim 2, wherein the first case and the second case are integral cavity forming cases. The sensing device of claim 2, further comprising a support coupled to the first case and the second case, wherein the support is provided with a bushing and guides the movement of the piston by the bushing. The method of claim 4, wherein the piston has a plate attached to the end in contact with the diaphragm, the elastic member is sandwiched between the bushing and the plate, the bushing is moved to adjust the distance between the bushing and the plate Sensing device, characterized in that possible. The sensing device according to any one of claims 1 to 5, wherein the blocking film can be moved to enable initial positioning of the blocking film with respect to the sensor unit. The sensing device according to any one of claims 2 to 6, wherein the liquid inlet tube and the temperature compensating tube are arranged side by side, and an end portion of each tube includes an enlarged portion having an enlarged inner diameter. The sensing device according to any one of claims 2 to 7, wherein a lower end of the liquid inlet pipe is blocked and a liquid inlet is formed in a side wall near the lower end. The sensing device of claim 8, wherein a cover is formed on the side wall to cover the liquid inflow hole and is spaced apart from the side wall. The sensing device according to any one of claims 2 to 9, wherein a valve is provided at the end of the temperature compensation tube. The light receiving element is provided with a light receiving cell and a padding plate provided with a hole in front of the light receiving cell, and the distance from one end of the moving direction of the blocking film in the hole (11). Hereinafter referred to as "moving distance") and the ratio of the width in the direction perpendicular to the moving direction of the barrier membrane is substantially equal to the ratio of the height of the tank corresponding to the moving direction distance to the cross sectional area of the tank at that height. Sensing device. The sensing device according to any one of claims 1 to 11, wherein the light receiving element comprises a solar cell. The sensing device of claim 1, wherein the piston is located below the cavity. A device for sensing the volume or level of liquid stored in a reservoir, A liquid inlet pipe inserted into the reservoir and provided with a hole in the lower end to allow liquid to flow from the lower end; A case member forming a cavity connected to the liquid inlet pipe so as to form a gas chamber including a space in the liquid inlet pipe; A piston positioned under the cavity, the piston being moved according to the pressure of the gas in the working side gas chamber, which changes according to the amount of liquid introduced into the liquid inlet pipe; A sensor unit having a light emitting element and a light receiving element facing each other; It includes a blocking film connected between the light emitting device and the light receiving device, One of the blocking film and the sensor unit is connected to the piston. A device for sensing the volume or level of liquid stored in a reservoir, A liquid inlet pipe inserted into the reservoir and provided with a hole in the lower end to allow liquid to flow from the lower end; A case member forming a cavity connected to the liquid inlet pipe so as to form a gas chamber including a space in the liquid inlet pipe; A piston moving according to the pressure of the gas in the working side gas chamber, which changes according to the amount of liquid introduced into the liquid inlet pipe, A sensor unit having a light emitting element and a light receiving element facing each other; It includes a blocking film connected between the light emitting device and the light receiving device, One of the blocking membrane and the sensor unit is connected to the piston, At least one of the light receiving element and the light emitting element has a padding plate having a hole located on the side facing the blocking film, the distance from one end of the moving direction of the blocking film in the hole (hereinafter referred to as “moving distance”) And the ratio of the width in the direction perpendicular to the movement direction of the barrier film is substantially equal to the ratio of the height of the tank corresponding to the movement direction distance to the cross sectional area of the tank at that height.