JPH0458116A - Wireless transmission type liquid gauge - Google Patents

Abstract

PURPOSE:To normally minimize the consumption of the battery on the side of the liquid gauge and to prolong the life of the battery by transmitting a liquid level signal only when a reed switch is turned on or off, namely, when a liquid level is varied. CONSTITUTION:A magnet 24 is disposed in a tape drum 12, the reed switch 25 which operates by the approach and leaving of the magnet accompanying the rotation of the tape drum 12 is provided, and a means 30 which sends the liquid level signal only when the reed switch 25 is turned on or off is provided. Namely, the reed switch 25 is turned on and off, so variation in the liquid level is detected and the liquid level signal at this time is transmitted. When the liquid level is not varied, the lead switch 25 is neither turned on nor off, so the liquid level signal is not transmitted. Consequently, the consumption of the battery on the side of the liquid gauge is minimized and the life of the battery 32 can be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid level gauge that transmits a level signal in an oil storage tank at a gas station or the like to a remote monitoring station by radio waves.

[Conventional technology]

In refueling facilities such as gas stations, underground tanks or above-ground tanks are installed to store various types of oil, and the liquid level of each tank is centrally monitored at one location.

Previously, level signals from level gauges installed in each tank were transmitted to monitoring stations via cables, but the longer the wiring required, the more extensive the undergrounding work and explosion-proofing measures were required.

Therefore, recently, systems are being provided that transmit liquid level signals to monitoring stations by radio waves, eliminating the need for laying cables.

In this wireless method, when transmitting the liquid level signal from each tank by radio wave, there are two ways to do it: always transmit it, or set a timer and transmit it at fixed intervals. However, it was structured to transmit data.

[Problem to be solved by the invention]

However, when the liquid level detection unit is equipped with a built-in battery, this leads to consumption of battery capacity and the battery life is extremely short, which is a major obstacle to practical application.

Therefore, an object of the present invention is to extend the life of the battery by transmitting a level signal only when there is a change in the liquid level in the oil storage tank.

[Means to solve the problem]

To achieve this objective, the present invention detects the liquid level by converting the amount of rotation from a reference position of a tape drum connected to a float provided in an oil storage tank and suspending the tape into an electrical signal. In wireless transmission liquid level gauges that transmit liquid level signals to remote monitoring stations via radio waves,
A magnet is disposed on the tape drum, and a reed switch is provided which is activated by the approach and separation of the magnet as the tape drum rotates, and means for transmitting the liquid level signal only when the reed switch is turned on and off. It is characterized by having

[Effect]

In the present invention, the float sinks or floats when the liquid level in the tank changes. As a result, the tape connected to the float moves up and down, and the tape drum rotates accordingly. Since the reed switch then turns on and off, it is detected that there is a change in the liquid level, and the liquid level signal at that time is transmitted. When there is no change in the liquid level, the reed switch is not turned on or off, so no liquid level signal is transmitted.

This minimizes battery consumption on the level gauge side and extends battery life.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to Examples.

FIG. 1 is an internal plan view showing the structure of a liquid level gauge according to the present invention;
FIG. 2 is an internal front view thereof, and FIGS. 3 and 4 are cross-sectional views taken along the I-1 line and ■-■ line in FIG. 2, respectively.

In these figures, 1 is the main body, 2 is the case, 3 is the flange, 4 is the terminal box, 5 is the dust cover, 6 is the sight glass, 7 is the wiper, 8 is the wiper knob, and 9 is the detector for measuring the water level in the tank. This is a water test cap for plugging water spouts.

A bearing frame 10.11 is installed in the case 2, and between the bearing frames 10.11, a tape drum 12 for winding the liquid level display tape T, a tape guide roller 13, and a weight tape guide roller. Each of the 14 axes is supported (see Figure 3). Coaxially with the tape drum 12, a weight tape drum 15 for winding up a weight tape T2 that provides a winding force for the liquid level display tape T on the tape drum 12 is slidably connected to the tape drum 12 by a clutch plate 16. They are movably provided, and after their positions are adjusted, they are pressed against each other by a spring 17 and are configured to rotate together.

The shaft of the tape drum 12 projects toward the bearing frame 11, and a first gear 18 is attached thereto as shown in FIG. The rotation is transmitted to the second gear 19 and decelerated by its gear ratio. The second gear 19 is a potentiometer 20
The rotation angle of the shaft of the tape drum 12 relative to the reference position is converted into an electrical signal. In addition, in FIGS. 1 and 2, 21 is a stopper gear, and the second gear 19
It has a stopper pin 22 and a stopper screw 23 for further decelerating the rotation of the potentiometer 20 and stopping the rotation when the rotation range of the potentiometer 20 reaches the upper and lower limits.

As shown in FIGS. 1 and 3, a plurality of permanent magnets 24 are attached to the clutch plate 16 on the circumference, and a reed switch 25 is attached to the bearing frame 11 facing the permanent magnets 24 ( (See FIGS. 1 and 2) Lead wires from the output terminal of the potentiometer 20 and the lead wires from the terminal of the reed switch 25 are collected in the terminal box 4 and guided to the signal transmitter.

FIG. 5 is a block diagram showing the configuration of the signal transmitter 30.

In the figure, an on/off signal from a reed switch 25 is input to a power supply reset circuit 31.

In this power supply set/reset circuit 31, a differentiation circuit or the like detects a change in the on/off state of the reed switch 25, and controls the power supply voltage applied to each circuit. Further, if there is no change in the on/off state for a certain period of time or more, a signal is issued to stop the application of the power supply voltage. In the figure, 32 is a battery, and 33 is a stabilized power source.

When the liquid level changes, the tape drum 12 rotates,
This turns the contacts of the reed switch 25 on and off.

Then, the power supply set-reset circuit 31 shown in FIG. 5 operates, turns on the switch circuit 34, and sends a voltage signal (
The analog signal) is converted into a digital signal by the A/D converter 35 and sent to the transmitting unit 37 through the CPU circuit 36. The transmitting unit 37 modulates this to a transmitting frequency,
A tank identification code or the like is attached to this, and the antenna 38 transmits it as a radio wave. The monitoring station that receives the radio waves demodulates the radio waves and records and displays them as liquid level signals.

Furthermore, there are multiple tanks in the refueling facility, and if a frequency is set for each transmitting unit of each tank, multiple receivers must also be installed at the receiving monitoring station. However, with the present invention, by attaching a tank identification code to the transmitting unit of each tank and transmitting, the monitoring station can identify which tank is transmitting the signal, and all tanks can be monitored with one receiver using the same frequency. It becomes easier.

〔Effect of the invention〕

As explained above, according to the present invention, the liquid level signal is transmitted only when the reed switch is turned on or off, that is, when the liquid level fluctuates, so the battery on the liquid level gauge transmits the signal. Since the battery is consumed only at certain times and not all the time, it is possible to extend the life of the battery.

Furthermore, since the combination of a magnet and a reed switch detects the presence or absence of a change in the liquid level, there is no mechanical contact, resulting in high reliability and durability, and can be constructed at low cost.

[Brief explanation of drawings]

FIG. 1 is an internal plan view showing the structure of a liquid level gauge according to the present invention;
Fig. 2 is an internal front view, Figs. 3 and 4 are cross-sectional views taken along line I-I and -■ in Fig. 2, respectively, and Fig. 5 is a liquid level signal transmitting section according to the present invention. FIG. 2 is a block diagram showing the configuration of FIG. 1: Main body 2: Case 3: Flange 4: Terminal box 5: Dust cover 6 = Peephole 7: Wiper 8: Wiper knob 9: Water test cap 10.11: Bearing frame 12: Tape drum 1
3: Tape guide roller 14: Weight tape guide roller 15: Weight tape drum 16: Clutch plate 17: Spring 18: First gear 19: Second gear 20: Potentiometer 21: Stopper 1m wheel 22: Stopper bin 23: Stopper screw 24 : Permanent magnet 25: Reed switch 30: Signal transmitter 31: Power supply set-reset circuit 32: Battery 33 Bi-stabilized power supply 34: Switch circuit 35: A/D converter 36: CPU circuit 37: Transmission unit 38: Antenna Patent applicant: Showa Kiki Kogyo Co., Ltd. Agent: Masu Kobori

Claims (1)

[Claims] 1. Convert the amount of rotation from a reference position of a tape drum connected to a float installed in an oil storage tank and suspending the tape into an electrical signal to detect the liquid level, and transmit this liquid level signal to a remote location using radio waves. In a wireless transmission liquid level gauge that transmits data to a monitoring station, a magnet is disposed on the tape drum, and a reed switch is provided that is activated by the approach and separation of the magnet as the tape drum rotates, and the reed switch operates on and off. A wireless transmission type liquid level gauge, characterized in that it is provided with means for transmitting the liquid level signal only when the liquid level signal is detected.