JPS60166825A - Electrostatic capacity measuring rod for detection of fuel oil level - Google Patents

Abstract

PURPOSE:To eliminate steps between two electrode sections by making the outermost circumference electrodes of a measuring electrode section and a comparison electrode section out of one metal pipe. CONSTITUTION:An extension pipe 16 is connected to the upper end of a detection rod 1 with a screw 14 and erected so that a comparison electrode section 2 positions near the bottom of a tank. The electrostatic capacity according to the temperature of a fuel oil is inputted into an oscillating section 4 from the comparison electrode section while the electrostatic capacity proportional to the depth of liquid thereinto from a liquid depth measuring electrode section 3 to be converted into a frequency proportional to the respective electrostatic capacities and transmitted to a control box C through a signal line R to indicate the level of liquid on a display. While a measurement is being conducted, dust mixed into the fuel oil settles. But the outermost circumference electrodes of the comparison electrode section 2 and the liquid depth electrode section 3 is free of steps as made out of one pipe 10 and eliminates the building up of dust at any point of the outermost electrodes to allow the electrostatic capacity of only the fuel oil to work. The dust infiltrated into the metal pipe through a passage 58 or 60 is discharged out through holes 48, 50 and 56 thereby in noway affecting the electrostatic capacity.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a fuel oil amount measuring device for measuring the remaining amount of fuel oil contained in a tank, and more specifically, an electrostatic meter for detecting the liquid level. Concerning a capacitance measuring rod.

(Prior art) Two metal plates forming a positive electrode and a negative electrode are placed facing each other in a fuel oil storage container, and the capacitance between the two electrodes changes in response to the liquid level of fuel oil such as gasoline. Many attempts have been made to measure liquid volume using this phenomenon.

In capacitance type liquid level gauges, the dielectric constant of the fluid to be measured is easily affected by temperature, and if the detection section and display section are connected by a long transmission signal line, stray capacitance increases. This causes a decrease in sensitivity.

In view of these circumstances, the present applicant proposed that the lower part of the weeping liquid depth measuring electrode part a formed in a tubular shape as shown in FIG. A comparison electrode section for measuring the dependent dielectric constant is attached to the upper part, and an oscillation means C for converting the capacitance information from the liquid depth measuring electrode section a and the comparison electrode section into digital signals is attached, and these are integrated into one body. We proposed a capacitance measuring rod shaped like a rod.

According to this device, it is not affected by changes in temperature or the length of the transmission signal line, and even the amount of liquid in an underground tank at a gas station can be measured with high accuracy from a remote location.

By the way, underground tanks at gas stations communicate with the atmosphere through air vents, and dust from the atmosphere easily enters, and dust settles and accumulates on the step d formed at the connection between the measurement electrode a and the reference electrode. However, there is a problem in that the electrostatic capacitance between the liquid depth electrode part a and the comparison electrode part A changes, and the measured value includes an error.

(Purpose) In view of these problems, the present invention has been developed to eliminate the difference in level between the two electrode parts by forming at least the outermost electrodes of the measurement electrode part and the comparison electrode part with a single metal pipe. The purpose is to provide a capacitance measuring rod.

(Structure) Therefore, details of the present invention will be described below based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention applied to a fuel oil remaining amount monitor at a gas station, and shows an underground tank T.
The capacitance measuring rod l according to the present invention, which is vertically installed in each case, has a reference electrode part 2 which is constantly immersed in fuel oil at the bottom.
, a liquid depth measuring electrode part 3 which outputs a capacitance value according to the oil level is built in at the top, and a reference capacitor which forms a reference capacitance is built into the top of this, and the static electricity of each electrode part 2.3 is built in. An oscillation transmission section 4 that converts a capacitance value into a frequency signal and outputs it is housed in a single tube. A frequency signal from the capacitance measuring rod I is transmitted via a signal line R to a control box C including a display means installed in an office or the like. This control box C is common to multiple measuring rods, and includes a numerical display meter that displays the tank number and amount of fuel oil, upper and lower limit notification lamps L for the liquid amount in each tank, and tank selection. Button S, printer P and its operation button 0, alarm buzzer B, and control box C
The data input key provided in the lower cover of the computer is provided with a key for data input, etc.

FIG. 2 shows an embodiment of the capacitance measuring rod according to the present invention, and the reference numeral 10 in the figure indicates that the upper end can be connected to an extension pipe 16 via a conductive member 12 with a screw 4.14. A metal pipe forms the casing of the oscillation transmission section 4 and the outermost electrodes of the measurement electrode section 3 and the comparison electrode section 2 (Figure i1). The oscillation transmission section 4 is made into a rod shape using epoxy resin 20 or the like so that the LC oscillation circuit 18 that converts capacitance information from the measurement electrode section 3 and the comparison electrode section 2 into a frequency signal can be inserted into the pipe 10. It is integrally constructed by molding and attaching an insulating member 22 to the lower part. 24 is the inner pole of the liquid depth measuring electrode section, which is connected to the pipe 10.
It is made of a metal pipe with an outer diameter smaller than the inner diameter of the pipe, and has a spacer 26 around its outer periphery. This inner pole 24
is an insulating member 3 provided with a connector 28 at one end thereof.
An insulating member 38 has a conductive coil spring 32 interposed on its outer periphery and is inserted into and set in a plug 34 attached to an insulating member 22, with a plug 36 protruding from the lower part of the inner pole 24. It is configured by fixing it. 40.42
．． 44 are the first . Of the second and third inner poles, the first inner pole 40 is made of a metal pipe fixed to the lower end of the insulating member 38, and the second inner pole 42 is made of a metal pipe with a connecting hole 43 that fits into the plug 36. A metal pipe is integrally fixed to the outer periphery of the third inner pole 44 made of a rod via an insulating member 46, and the outermost circumferential pole 10 and the second inner pole 44 are paired to form one pole and the first inner pole. 40 and m3 inner pole 44 with conductive member 49
The two poles are connected to each other to form the other pole. A plug member 52 having a through hole 48.50 communicating with the reference electrode portion is attached to the lower end of the second inner electrode 42, and is removably fixed to the metal pipe IO forming the outermost circumference iL pole with a screw 54, At the same time, electrical connection between the outermost electrode 10 and the second inner pole 42 is realized. In addition, the symbol 56.58.6 in the figure
62.64 also indicates a through hole drilled in the metal pipe 10 to allow fuel oil to flow in and out of each electrode part.
．． 66 indicates a sealing member for maintaining liquid tightness, and 68 indicates a lead wire connecting the other pole of the comparison electrode section 2 and the oscillation transmission section.In this embodiment, at the upper end of the detection rod l Extension pipe 16
When connected with screws 14 and placed vertically so that the reference electrode part 2 is located near the bottom of the tank, a capacitance J11 corresponding to the temperature of the fuel oil will be generated from the reference electrode part, and a liquid will be transferred from the liquid depth measuring electrode part 3. Capacitance proportional to the depth is input to the oscillating unit 4, converted to a frequency proportional to each capacitance 4t, and transmitted through the signal line R to the control box C (Fig. 1) to compensate for temperature changes. The exact amount of liquid poured will be displayed on the display. When measurements are carried out in this way, dust mixed in the fuel oil settles out, but the outermost electrodes of the reference electrode part 2 and the liquid depth electrode part 3 are formed of -wood pipe lO. The surface of the outermost electrode, which is immersed in fuel oil, is always surrounded by fuel oil, and the capacitance of the fuel oil alone is reduced. acts.

Dust that has entered the metal pipe through the through holes 58 to 60 settles between the electrodes and is discharged to the outside through the holes 48, 50, and 56 at the lower end, increasing the capacitance. There will be no impact.

(Effects) -1 As described above, according to the present invention, the outermost electrodes of the liquid depth measuring electrode part and the reference electrode part are used as a common electrode and are formed by one metal pipe, so that the liquid depth measuring electrode It is possible to eliminate the step between the electrode section and the reference electrode section, which not only makes it possible to accurately measure the liquid depth without the capacitance being affected by dust, but also eliminates the need for parts such as joints. The structure can be simplified and the strength can be improved.

[Brief explanation of the drawing]

FIG. 1 is a device configuration diagram showing an embodiment of an oil amount measuring monitor to which a capacitance measuring rod according to the present invention is applied, and FIG.
FIG. 3 is a sectional view of a device showing an embodiment of the capacitance measuring rod of the present invention, and FIG. 3 is a side view showing an example of a conventional capacitance measuring rod. 1... Capacitance detection rod 2... Reference electrode part 3.
...Liquid depth measurement electrode part 1o...Metal pipe Applicant Tokyo Tatsuno Co., Ltd. Agent Patent attorney Haruto Nishikawa Katsuhiko Kimura Figure 1

Claims (1)

[Claims] A capacitance measuring rod for detecting the amount of fuel oil in which the outermost electrode of the reference electrode part and the outermost electrode of the liquid depth measuring electrode part are formed as a common electrode.