JPH0663810B2 - Wireless liquid level signal transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a device for wirelessly transmitting the liquid level of an underground tank buried in a gas station or the like to a remote place.

(Prior Art) The amount of liquid such as fuel oil stored in an underground tank is usually managed by converting it into an electric signal by a float type level gauge and transmitting it to a monitor device such as an office through a transmission line. .

(Problems to be Solved by the Invention) However, there is a problem in that wiring is required in consideration of explosion proof and cost is increased because a transmission line continues between the underground tank and the monitor device.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a novel liquid amount measuring device capable of eliminating wiring work.

(Means for Solving the Problem) In order to solve such a problem, in the present invention, means for detecting the liquid level at each set time T0 and liquid level data are compared with the previous liquid level data. The first signal is output when the liquid level is increasing, the second signal is output when the liquid level is decreasing, and the third signal is output when the liquid level is substantially unchanged. Means and the first signal, the second signal, and the third signal of the comparison means, respectively, for time intervals T1, T2, T
3 (provided that T1 <T2 <T3) is activated and liquid level data is transmitted by radio frequency.

(Function) When replenishing from the tanker, the liquid level data is transmitted in a cycle as short as possible, and during normal consumption, which is less urgent than this, the number of times the liquid level data is transmitted is reduced to reduce unnecessary consumption of the power supply battery. While suppressing, data is transmitted to the destination at a frequency according to the situation.

(Example) Therefore, the details of the present invention will be described below based on an illustrated example.

FIG. 1 shows an embodiment of the liquid supply equipment to which the present invention is applied. In the figure, reference numeral 1 is a transmitter provided in the underground tanks 2 and 2, and 3 is a remote place from the underground tank. A receiver installed in the office 4 is configured to transmit the liquid level of the underground tank by a carrier wave of radio frequency.

FIG. 2 shows an embodiment of the above-mentioned transmission device, in which reference numeral 10 is a control device composed of a microcomputer, and a battery 11 having an output voltage higher than a voltage required by the device. A timer means 1 that always receives power from the power supply terminal 10a via the voltage regulator 12 and always receives power from the voltage regulator 12 to operate.
The start signal from the start signal 3 is received by the start signal input terminal 10b, and the start and stop are repeated intermittently at a constant cycle T0, for example, at intervals of 20 seconds, and at the time of stop, the start signal from the timer means waits in a restartable state. Is configured.

Reference numeral 14 denotes a voltage drop detection means, which detects the output voltage of the battery 11 and when the battery voltage drops below the rated input voltage of the voltage regulator 12, the voltage detection terminal 10c of the CPU 10.
Is configured to output a signal to.

A liquid level data storage means 15 is provided for the voltage regulator 12
The liquid level data from the measuring means 20 which will be described later is stored by constantly receiving the operating voltage via the.

Reference numeral 20 denotes the liquid level measuring means described above, which is rotated by a float F that moves up and down according to the liquid level, and which receives a working voltage from a regulator 21 and a voltage for converting an output voltage from the potentiometer 22 into a frequency- The frequency conversion means 23 is configured to receive power from the regulator 12 via the first switch 16 and output a frequency signal to the microcomputer 10. Reference numeral 17 denotes a modulation transmission unit, which receives power supply from the voltage regulator 12 via a second switch 18 which is turned on by a signal from a transmission control unit 30 which will be described later, and generates a carrier wave by the measurement data of the liquid level measurement unit 20. It is configured to modulate and send the measurement data as a radio signal from the antenna 19.

FIG. 3 shows an embodiment of the modulation transmission means, in which reference numeral 24 is the liquid level data and the voltage drop alarm signal from the microcomputer 10, and the carrier is the oscillating circuit 2.
Upon receiving the carrier wave from the carrier 5, the liquid level data and the voltage drop warning signal are placed on the carrier wave and output to the antenna 19.

By the way, the oscillator circuit 25 is operated by the switch 26.
The frequency control signals from the band setting circuit 26 for outputting a band selection signal by a and 26b and the frequency control signal from the frequency setting circuit 27 for setting different frequencies in the same band by the switches 27a, 27b and 27c are received. This prevents crosstalk between neighboring gas stations and tanks within the same gas station by selecting a band for each gas station and a different frequency within the same gas tank for the same gas station. As a result, highly reliable data transmission is possible.

FIG. 4 shows an embodiment of the above-mentioned control circuit. In the figure, reference numeral 31 is a comparison means, and a liquid level data storage means 15 and a liquid level detection section 3 are generated by a start signal of the timer means 13.
The liquid level data of 0 is compared, and when the liquid level is increasing, the first signal S1 is generated, when the liquid level is decreasing, the second signal S2 is further generated, and the liquid level is substantially increased. When it is constant, the third signal S3 is output.
Reference numeral 32 denotes a transmission cycle selection circuit, for example, in the case of the S1 signal when the liquid level is rising, the count number N1 = 1
And S2 signal when the liquid level is decreasing, N2 = 15, and S3 when the liquid level is almost constant.
When it is a signal, N3 = 180 is output to the counter 33 described later. Reference numeral 33 is a counter means for determining the transmission cycle, which counts the number of times the CPU 10 is activated, that is, the number N of signals from the timer means 13, and outputs a signal when the number set by the transmission cycle selection circuit 32 is reached. The switch 18 is turned on and the count content is reset to zero.

Next, the operation of the apparatus thus configured will be described with reference to the flow charts and timing charts shown in FIGS.

When power is supplied from the battery 11 to operate the device, the microcomputer 10 enters a standby state in which the function of receiving the activation signal from the timer means 13 is maintained, and the timer means 13 starts the time counting operation ( Step a). When the time measured reaches T0, the timer means 13 outputs a start signal (step B) (I in FIG. 6). As a result, the microcomputer 10 exits the standby state and shifts to the startup state,
The first switch 16 is turned on to supply operating power to the liquid level detection unit 20 (step C). The liquid level detector 20 is
The voltage signal from the potentiometer 22 output according to the liquid level is converted into a frequency signal by the voltage-frequency conversion means 23 and output to the microcomputer 10 (step d). The microcomputer 10 counts this frequency signal for a certain period of time, turns off the first switch 16 after the count ends, cuts off the power to the liquid level detection unit 20, counts up the number of startups N, and further inputs it. The liquid level data F1 is compared with the previous liquid level data F0 stored in the liquid data storage means 15.

[When the liquid supply device is operating] (Fig. 6, III) In this case, the liquid is being consumed by supplying liquid to the vehicle.
The measured liquid level F1 becomes smaller. Therefore, the transmission cycle selection means 32 selects the transmission cycle N2, sets this in the counter means 33, and updates the data in the liquid level data storage means to the current measured value without operating the transmission section (step F). ~ Chi, Oh). When the series of operations is completed, the CPU 10 returns to the standby state,
Reduces unnecessary power consumption (wa).

When the above-described operation is repeated (steps 1 to 3) and the count number of the counter means 33 coincides with N2 (step), the counter means 33 turns on the second switch 18.
Then, power is supplied to the modulation and transmission means 17, and the sampled liquid level data is transmitted a plurality of times, and then the second switch 18 is turned on.
The FF is set, the modulation transmission means 17 is stopped, and the counter means 33 is reset to zero (step). Further, the data in the liquid level data storage means 15 is updated, and then the CPU is switched to the standby state.

Thereby, the timer means 13 and the liquid level data storage means 1
5, voltage drop detection means 14, and voltage regulator 12
While only the operating state is maintained and the CPU is kept in the standby state, the modulation transmitting means 17 and the measuring means 20 are in the idle state, and the power consumption is suppressed.

[At the time of replenishment to the underground tank] (Fig. 6 I) In this case, the fuel level is being replenished to the underground tank by unloading from the tank truck and the liquid level is rising. The liquid level F1 becomes larger than the data F0 of the liquid level data storage means 15 (step
F). Therefore, the transmission cycle selecting means 32 sets the shortest transmission cycle N1 in the counter (N1 = N in this embodiment).
1, that is, the mode in which transmission is performed each time the CPU 10 is activated is selected), and the second switch 18 is turned on to activate the modulation transmission means 17 to transmit the measured liquid level data F1 multiple times. After the transmission is completed, the second switch 18 is turned off to stop the power supply to the modulation transmission means 17, and the counter means 33 is reset to zero (step). After zeroing,
The contents of the liquid level data recording means 15 are updated (step
E) Steps for returning the CPU 19 to the standby state.

Hereinafter, the liquid level data is transmitted in the shortest period by the period (l) during which the liquid level rise is detected by the steps (a) to (f) to prevent the liquid from overflowing from the tank. . As a result, only the timer unit 13, the liquid level data storage unit 15, the voltage drop detection unit 14, and the voltage regulator 12 remain in the operating state, and the CPU remains in the standby state, while the modulation transmission unit 17 and the measurement unit 20 stop. In this state, power consumption is suppressed.

[At rest due to closing of the store] (Fig. 6 I) When the operation of the liquid supply device is stopped and the tank is neither replenished with liquid nor consumed, the liquid level changes. Since there is no (step power), the transmission cycle selection means 32
Sets the longest cycle N3 in the counter means 33 (steps F, C, C).

In this way, each time the counter content reaches N3, the second switch 18 is turned on to activate the transmission modulation means 17, and after transmitting the data a plurality of times, the second switch 18 is turned off.
And at the same time, the counter means 33 is reset to zero (step
Le).

Hereinafter, in this manner, the liquid level data is transmitted in a cycle such that the minimum necessary data can be grasped.

Thereby, the timer means 13 and the liquid level data storage means 1
5, voltage drop detection means 14, and voltage regulator 12
While only the operating state is maintained and the CPU is kept in the standby state, the modulation transmitting means 17 and the measuring means 20 are in the idle state, and the power consumption is suppressed.

[When the voltage of the power supply battery drops] When the power supply battery 11 is used up for a long period of time and the output voltage of the battery drops to a reference value, the voltage drop detection means 14 outputs a voltage drop warning signal. Counter means 3
When the signal is output from 3 (Step F, J,
F), the CPU turns on the second switch to operate the transmission modulator 17. As a result, after the liquid level data is transmitted a plurality of times, the battery voltage drop alarm is also transmitted. After transmitting these data, the second switch 18 is turned off (step
Y) After updating the data in the liquid level data storage means 15 (e), the CPU returns to the standby state (w).

In this embodiment, the float type liquid level indicator is taken as an example, but the capacitance type liquid level indicator as shown in FIG. 7, that is, the positive electrode 40 and the negative electrode 40 are coaxially connected to each other. Depth measuring electrodes 42 arranged at intervals to allow the inflow of water
And a comparison electrode 43 for measuring the dielectric constant of the liquid which is located below it and is always immersed, are integrally formed in a rod shape so as to be erected in the tank K, and the liquid depth measuring electrode 42 is also provided. And an oscillator 44 for converting the liquid level into a frequency based on the signal from the comparison pole 43 is used, not only the same effect is obtained, but also the frequency signal from the data output means included in the oscillator is used. Therefore, the voltage-frequency conversion means can be eliminated.

In addition, in this embodiment, the transmission cycle is set and detected by the number of times the CPU is activated, that is, the number of times the liquid level data is sampled. However, the transmission cycle is set by a signal from the activation timer or a separately provided timer. Even if the detection is performed, the same operation is achieved.

(Effects of the Invention) As described above, in the present invention, the means for detecting the liquid level at each set time T ₀ and the liquid level data compared with the previous liquid level data increase the liquid level. If there is 1st
In the case where the liquid level is decreasing, a second comparing means for outputting a second signal, and when the liquid level is not substantially changing, a battery for power supply, and a voltage for the battery are The time intervals T ₁ and T ₂ (however, depending on the voltage drop detection means for outputting the voltage drop warning signal when the voltage drops below the reference value and the first signal and the second and third signals from the comparison means (however, T ₁ <
And a means for transmitting the liquid level data wirelessly at T ₂ ) and for transmitting the voltage drop alarm signal in association with the transmission of the liquid level data when the voltage drop alarm signal is output. Therefore, while reliably detecting the fluctuation of the liquid level in the oil storage tank, the transmission cycle is automatically adjusted depending on whether the fluctuation is increased or decreased to suppress the battery consumption, and there is a risk of an emergency. In some cases, not only can the liquid level data be transmitted in a short cycle for reliable liquid level management, but when the battery is exhausted, a low voltage warning signal is sent along with the transmission of the liquid level data. The replacement can be promoted at a frequency according to the consumption speed of the battery, and a reliable operation can be guaranteed.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a liquid supply facility to which the present invention is applied, FIG. 2 is a block diagram of an apparatus showing an embodiment of the present invention, and FIG. 3 is an embodiment of a modulation transmission means. FIG. 4 is a block diagram showing the same, FIG. 4 is a block diagram showing an embodiment of means for determining a transmission cycle, FIG. 5 is a flow chart showing the operation of the same apparatus, and FIGS. Timing diagrams and FIGS. 7A and 7B are views showing another embodiment of the liquid level detector. 1 ... Wireless liquid level transmitter, 2 ... Underground tank 3 ... Receiver, 19 ... Antenna 20 ... Liquid level measuring unit 22 ... Potentiometer 30 ... Transmission cycle control means, F ... Float

Front page continuation (72) Inventor Makoto Shimizu 2-12-13 Shibaura, Minato-ku, Tokyo Tatsuno Co., Ltd. (72) Naoaki Natori 2-12-13 Shibaura, Minato-ku, Tokyo Tatsuno Co., Ltd. (56) References JP-A-59-5921 (JP, A) JP-A-57-13596 (JP, A) JP-A-61-9798 (JP, A)

Claims (1)

[Claims] 1. A means for detecting the liquid level at each set time T ₀ , and a first liquid level when the liquid level is increased by comparing the liquid level data with the previous liquid level data. When it is decreasing, a second comparing means for outputting a second signal when the liquid level is not substantially changed, a battery for power supply, and the voltage of the battery is below a reference value. Voltage drop detection means for outputting a voltage drop alarm signal when the voltage drops to T1 and the first signal and the second and third signals from the comparison means, the time intervals T ₁ and T ₂ (where T ₁ <T ₂ ) and wirelessly transmits the liquid level data, and when the voltage drop alarm signal is output, means for transmitting the voltage drop alarm signal in association with the transmission of the liquid level data. A wireless liquid level signal transmission device comprising: