JP3072654B2 - Float type liquid level measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a float type liquid level measuring device for converting a vertical movement of a float caused by a liquid level change into a rotation of a drum via a tape.

[0002]

2. Description of the Related Art A float type liquid level measuring device for measuring the liquid level of an underground tank or the like based on the vertical movement of a float, winds the other end of a tape having one end connected to the float around a winding drum, and floats the float. Is converted into the rotation of the take-up drum,
Further, the rotation is converted into an electric signal by a mechanical-electric conversion means such as a potentiometer and transmitted. In such an apparatus, the winding drum is configured to have a small diameter in order to reduce the size, so that the tape is wound in an overlapping manner. For this reason, when the tape expands and contracts due to the temperature and the thickness changes, or when the diameter of the drum changes due to the temperature, a deviation occurs between the liquid level fluctuation and the number of rotations of the winding drum, thereby causing a measurement error. There is. In order to solve such a problem, a method of providing a temperature detecting means and correcting it with a signal from now on is also considered. There is a problem that can not respond. The present invention has been made in view of such a problem, and an object of the present invention is to provide a novel float type that can automatically correct an error caused by a change in tape thickness or drum diameter. It is to provide a liquid level measuring device.

[0003]

According to the present invention, a tape connected to a float is wound around a drum and an output from a detecting means for detecting the rotation of the drum is provided. Diameter D of the tape and thickness t of the tape
In a float type liquid level measuring device for measuring a tank liquid level using a relational expression with a constant as a constant, at least two peculiar parts formed on the tape corresponding to a predetermined liquid level in the length direction and the peculiar parts are detected. And a constant changing means for changing the constants D and t based on the output of the rotation detecting means when at least two of the unique parts are detected.

[0004]

The relationship between the liquid level and the data of the rotation detecting means is expressed by an equation including two constants D and t. Since the data from the rotation detector at the time when each unique portion is detected is a conversion signal at a known liquid level, two equations are obtained from the data of the two unique portions, where two constants D and t are unknown. I do. As a result, the diameter D of the drum and the thickness t of the tape can be known by solving these two equations. By converting the signal from the rotation detecting means into a liquid level using an equation including a newly calculated constant, an accurate liquid level can be obtained regardless of changes in the drum diameter D and the tape thickness t.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows an embodiment of a liquid supply system to which a liquid level measuring device according to the present invention is applied. Reference numerals 2 and 2 in the figure denote supply of fuel oil by a lorry from a supply valve (not shown). Float type liquid level transmitters 3 and 3 are provided in the underground tank for receiving the water, and these float type liquid level transmitters 3 and 3 have a built-in signal processing unit having a transmitting function to wirelessly control the liquid level. It is configured to transmit from the antenna 4 by radio waves and receive by the receiving device 6 provided in the office 5.

FIG. 2 shows an embodiment of a float type liquid level transmitting apparatus used in the above-mentioned equipment. In the figure, reference numeral 9 denotes a tape drum for winding a scale tape 11 connected to a float 10. The constant torque spring 14 wound around the reels 12 and 13 constantly urges the tape 11 in the winding direction.

As shown in FIG. 3, the scale tape 11 is provided with a through hole, a reflector, and a conductive layer at two positions corresponding to a predetermined distance in the length direction, for example, L ₁ and L ₂ from the bottom of the tank. , A unique portion such as a magnetic layer to form the first and second marks 15 and 1
6 are provided. Returning again to FIG.
Is a rotation detector composed of a potentiometer, a pulse transmitter, and the like connected to the tape drum 9 via a train wheel 18 via a train wheel 18. An up / down movement of the float 10, that is, an electric signal proportional to the rotation speed of the drum 9. In this embodiment, a signal processing circuit 20 described later is converted into a voltage signal by a lead wire 19.
Is output to Reference numeral 21 denotes a unique part detector for detecting the marks 15 and 16 provided on the tape.
In this embodiment, the light emitting element 22 and the light receiving element 23 are arranged at positions facing the marks 15 and 16 with the tape 11 interposed therebetween. Reference numeral 24 in the figure indicates a transmitting antenna housed in a hole 25 formed in the pit wall.

FIG. 4 shows an embodiment of the signal processing circuit 20 described above. In the figure, reference numeral 30 denotes a microcomputer constituting control means, and a voltage regulator 3.
1 receives electric power from the battery 32 to the power supply terminal 30a via
Further, the start signal from the timer means 33 which is always supplied with electric power from the voltage regulator 31 and is always operating, and the singular part detection signal from the singular part detector 21 are received by the activating signal input terminal 30b, and these activating signals or It is configured to operate for a fixed time only when the unique part detection signal is input, and to always wait in a restartable state, that is, a standby state. Reference numeral 33 denotes the above-mentioned timer means, which is configured to output a start signal at a constant period T0, for example, at intervals of 15 seconds, and to operate the microcomputer 30 intermittently. Numeral 34 denotes a data storage means which receives the supply of the operating voltage constantly via the voltage regulator 31 and takes in the liquid level data F _{+ 1} from the liquid level measuring means 40 which will be described later. Stored while updating as ₀ ,
Further, a numerical value N for determining a transmission cycle to be described later is stored.

Numeral 40 is a liquid level measuring means, which is supplied with a reference voltage via a voltage regulator 41 and is proportional to the rotation speed of the tape drum 9 which responds to the vertical movement of the float 10 installed in the tank 2. It comprises a potentiometer 42 for outputting a voltage signal V, and a voltage-frequency converting means 43 for converting the voltage signal V from the potentiometer 42 to a frequency F. Power is supplied from a first switch 44 controlled by the microcomputer 30. , And outputs a frequency signal corresponding to the liquid level to the microcomputer 30. The singular part detector 21 includes a third switch 45 controlled by the microcomputer 30.
From the tape 11, marks 15 and 16 on the tape 11.
Is detected, a unique part detection signal is output to the activation signal input terminal 30b.

Numeral 47 denotes a modulation transmitting means which receives power from the voltage regulator 31 through a second switch 48 controlled by the microcomputer 30 and measures measured data from the liquid level measuring means 40, that is, the liquid level. The transmitted frequency F is transmitted from the antenna 24 as a radio signal.

FIG. 5 shows an embodiment of a receiving apparatus. In the figure, reference numeral 50 denotes a buffer for temporarily storing a frequency signal F indicating the liquid level received by an antenna 51, 52
Is a calibration signal determining means for determining whether or not the frequency signal F stored in the buffer 50 is a signal caused by the marks 15 and 16 on the scale tape 11, and if the signal is a calibration signal, the frequency signal F The calibration signal storage means 53 is configured to be stored. Numeral 54 denotes a constant calculating means for calculating the diameter D of the tape drum 9 and the thickness t of the tape 11 based on the calculation formula stored in the constant calculation formula storage means 55 and the frequency signal F of the calibration signal storage means 53, and It is configured to output to the storage means 56. Numeral 57 denotes a liquid level calculating means which converts the frequency signal F stored in the buffer 50 into the tank in the tank by using the constant of the constant storing means 56 and the liquid level calculating formula stored in the liquid level calculating formula storing means 58. It is configured to convert to a liquid level. 59 is a liquid level calculating means 57
From the liquid level data and the liquid amount calculation formula stored in the liquid amount calculation formula storage means 60, the remaining amount (liter) and the free space of the tank 2 are calculated from the liquid level data, and these data are displayed on the display means 61. Is configured to be output.

Next, the operation of the above-configured apparatus will be described with reference to the flowcharts shown in FIGS. When the battery 32 is set and power is supplied to the liquid level transmission device, the microcomputer 30 waits in a standby state in which only a function sufficient to receive a start signal from the timer means 33 is left. The timer means 33 performs a counting operation upon receiving a supply of continuous power (step b), when the counting start time T ₁ (15 sec) has elapsed, the timer means 33
(Step b) (Fig. 8)
B) The microcomputer 30 exits the standby state and shifts to the operating state. The microcomputer 30 turns on the first switch 44 to supply power to the liquid level measuring means 40 (step C). The liquid level measuring means 40 converts the voltage output from the potentiometer 42 into a frequency signal by the voltage-frequency converting means 43 according to the liquid level, and outputs the frequency signal to the microcomputer 30. The microcomputer 30 counts the frequency signal for a certain period of time to obtain a frequency signal F _{+ 1} (step d), and the first switch 4
4 to OFF Disconnect power to the liquid level detection unit 40, also respectively compare the frequency signal F ₀ of the previous stored in the frequency signal F ₊₁ and the data storage unit 34 (step e).

[Non-supply] (FIG. 8C) In this case,
Since the fuel oil in the underground tank 1 has been consumed by the liquid supply to the vehicle or the liquid level is kept constant, the frequency signal F _{+ 1} measured just now is stored in the data storage unit 34.
Is smaller than or the same as the previous frequency signal F ₀ (step f). Therefore, the microcomputer 3
0 turns off the third switch (step).
Thus, when the liquid level decreases, the power supply to the unique portion detector 21 is cut off to prevent power consumption. Therefore, the microcomputer 30 starts and stops at the timing of only the start signal from the timer means 33. Next, it is determined whether the numerical value N is “0” or not. In this case, since the numerical value N is not set and N = 0 (step S1), the second switch 48 is turned on to supply power to the modulation transmitting means 47, and the frequency signal F _{+ 1} measured just now is transmitted. After the transmission, the second switch 48 is turned off to stop the transmission modulating means 47, and the transmission interval, for example, 10
Set (Step nu). After this series of operations, the microcomputer 30 updates the previous frequency signal F ₀ stored in the data storage means 34 (step
), The standby state is maintained until the next start signal is input from the timer 33 (step e).

In this way, when the start signal is input again from the timer means 33 (step b), the above-described steps (c) to (h) are executed. Therefore, the process jumps to step (w), subtracts the previous value N by 1 (step w), and does not operate the modulation transmitting means 47.
The previous frequency signal F ₀ of the data storage means 34 is only updated (step), and the apparatus enters the standby state (step オ). As a result, the entire apparatus is stopped while leaving only the minimum functions necessary for the next start, thereby minimizing power consumption.

Such an operation is repeated (step
After the numerical value N is "0", that is, nine non-transmission states are continued (step), the microcomputer 30 turns on the second switch 48 and turns on the modulation transmission means 4.
7 and transmit the frequency signal F _{+ 1} just measured, then turn off the second switch 48 to set the transmission modulation means 47
And set 10 to the numerical value N (step
Nu).

On the other hand, on the receiving device 6 side, the frequency signal F _{+ 1} received by the antenna 51 is temporarily stored in the buffer 50 (step y), and the liquid level calculating means 57
0, the frequency signal F _{+ 1} is read out, and the constant storage means 56
In consideration of the diameter D of the tape drum 9 and the thickness t of the tape 11 stored in the storage device, the liquid level is calculated by the calculation formula of the liquid level calculation formula storage means 58. The liquid amount calculating means 59 converts the liquid level from the liquid level calculating means 57 into a liquid amount based on the calculation formula stored in the liquid amount calculating formula storage means 60, and displays it as a liquid amount on the display means 61. (Stepper). In this case, since the signals originating from the unique portions 15 and 16 of the tape 11, that is, the calibration signals are not added (step S), the process waits for the next signal input (step S).

[When refilling the underground tank] (FIG. 8B) When the start signal is input from the timer means 33 (step B), the microcomputer 30 shifts from the standby state to the operating state and switches the first switch. By turning on 44 (step c), a frequency signal F _{+ 1} from the liquid level detecting means 40 is obtained (step d). Next, the first switch 44 is turned off, and the frequency signal V _{+ 1} measured just now and the previous frequency signal F stored in the data storage means 34 are stored.
Compare with ₀ (Step E).

In the present case, since the fuel oil flows from the lorry into the underground tank 1 through the supply valve 2 and the liquid level is rising, the current frequency signal F _{+ 1} is changed to the previous frequency signal F _It becomes larger than ₀ (step f). For this reason, the microcomputer 40 turns on the third switch 45 to supply electric power to the unique portion detector 21 to make it operate (step). Next, the second switch 48 is turned on to transmit the current frequency signal F _{+ 1,} and after the transmission is completed, the second switch 48 is turned off to stop the modulating transmission means 47 and further set the numerical value N to 10 (step nu). ). Next, the liquid level data F ₀ stored in the data storage means 45 is updated (step), and the process returns to the standby state (step オ).

Thereafter, while the replenishment is being performed and the tank liquid level is rising, steps (b) to (f) and steps (li) to (e) are repeated to change from the standby state to the operating state. Each time it changes, turn the second switch 48 to O
N, the modulation transmitting means 47 is operated, and the liquid level measuring section 40
This is transmitted each time the frequency signal F _{+ 1} is obtained from. These frequency signals F _{+ 1} are transmitted to the receiving device in step (Y).
It is displayed as a liquid amount through the process of (T).

As the replenishment proceeds and the liquid level rises, the first mark 15 provided on the tape 11 passes through the unique part detector 21. In the present state, since the singular part detector 21 is supplied with electric power, a singular part detection signal is input to the microcomputer 30 (step S1).
F) Thus, the microcomputer 30 with or without activation signal from the timer means 33, that is even without receiving the start signal from the timer means 33 immediately starts (P ₁ in Lee in FIG. 8). When the mark 15 has passed, the microcomputer 30 enters the operations of steps (c) to (f) and steps (re) to (e) and outputs the frequency signal F _{+ 1} of the liquid level detecting means 40. Send. When the microcomputer 30 is activated by a signal from the unique part detector 21, a signal form different from that when the microcomputer 30 is activated by the timer means 33,
For example, a calibration signal in a form that can be distinguished from normal liquid level data is transmitted by a modulation method such as changing the frequency or attaching a special identification mark (S _{1 in} FIG. 8). After the transmission is completed, the system enters the standby state in the same procedure as in the normal startup (step e). On the other hand, when the frequency signal F _{+ 1} to which the calibration signal at the time of passing the mark is added is stored in the buffer 50, the receiving device 6 calculates and displays the liquid volume (steps Y and T), and outputs the calibration signal. Is added (step) and the liquid level to which the calibration signal is added is
And when it is determined in the calibration signal determination unit 52 is substantially equal to the height L ₁ indicating a mark 15, and stores the frequency signal F ₊₁ to the calibration signal storage unit 53 (step Tsu), also the timer unit 62 is activated at the same time To start timing.

When the unique unit 15 passes through the detector 21 and the next start signal is output from the timer means 33 (step S1).
B) The microcomputer 30 starts up as usual (step c), and transmits the liquid level data in steps (d) to (f) and steps (re) to (e). Since this frequency signal has no calibration signal added thereto, it is normally processed in steps (Y), (T), and (D) and displayed on the display means 61 as a liquid amount.

When the replenishment of the fuel oil progresses and the liquid level further rises, the second mark 16 provided on the tape 11 passes through the unique portion detector 21 and when the unique portion detection signal is input from the detector 21. , The microcomputer 30 is immediately activated regardless of the presence or absence of the activation signal from the timer means 33 (P ₂ in FIG. 8A) (step F). Thereby, the microcomputer 30 performs step (c).
Steps (f) to (e) and steps (e) to (e) are performed, and a calibration signal is added to the frequency signal of the liquid level detection means 40 at the time when the mark 16 has passed, and transmitted (see FIG. 8B). S ₂ ), and enters the standby state after the transmission is completed (step o).

On the other hand, when the frequency signal F _{+ 2} to which the calibration signal is added is stored in the buffer 50, the receiving apparatus displays the liquid volume (steps Y and T), and the calibration signal is added (step Y). step Les) liquid level is determined by L ₁ not equal calibration signal determination unit 52 (step SEO), and the elapsed time is a constant value T of the timer means 62, for example in the case of less than 10 minutes (step ne), the buffer 50 _Is stored in the calibration signal storage means 53. In this manner, two frequency signals for calibration F ₊₁ and F
_{When +2} is stored in the calibration signal storage unit 53, the constant calculation unit 54 calculates the calculation formula stored in the constant calculation expression storage unit 55 and the two data F ₊₁ , F 2 in the calibration signal storage unit 53.
_{By +2} , the thickness t of the tape drum 9 and the tape 11 is calculated.

That is, assuming that the diameter of the tape drum 9 is D and the thickness of the tape 11 is t, the diameter Dn when the tape drum 9 enters the nth rotation is as follows: Dn = D + (2n-2) t , The length L of the tape wound on the drum 9
_n is π ｛(D−2t) + tn｝ n obtained by integrating this equation. On the other hand, the number of rotations n is proportional to the output of the rotation detector 17, in this embodiment, the frequency F.
−2t) + tF｝ F. Therefore, by obtaining frequency signals F ₊₁ and F ₊₂ at predetermined liquid levels L ₁ = 80 cm and L ₂ = 120 cm, L ₁ = π ＝ (D−2t) + tF ₊₁ ｝ _{F +1 L 2 = π {(} D-2t) + tF +2} F +2 comprising two equations can make a can be calculated and the tape drum D is unknown, the tape thickness t.

The tape drum D calculated as described above
Then, the data of the tape thickness t is stored in the constant storage means 56 (step na). As a result, the constant is updated to a highly reliable constant taking account of aging and temperature changes. The length of the tape 11 also changes depending on the temperature and the like. However, since there is an extremely high correlation between the length and the thickness, practically sufficient measurement accuracy can be obtained by calibrating taking the thickness t into consideration. .

If 10 minutes or more have passed since the first calibration frequency signal F _{+ 1} was output (step N), the frequency signal between the two frequency signals F _{+ 1} and F _{+ 2 was not detected} . Since the relevance is low, the timer means 62 discards the data in the calibration signal storage means 53, returns to the first step, and interrupts the calibration work (step S). Then, a liquid level is calculated from the liquid level data based on the previous constants D and t stored in the constant storage means 56, and this is converted into a liquid amount. In this embodiment, the rotational speed of the tape drum is converted into a frequency and transmitted. However, the same effect can be obtained even when the rotational displacement is converted into a voltage or the number of pulses and transmitted. it is obvious.

[0027]

As described above, in the present invention,
The float connected to the float is wound around the drum, and the output from the detecting means for detecting the rotation of the drum, and the float measuring the tank liquid amount using a relational expression using the diameter D of the drum and the thickness t of the tape as constants. In the liquid level measuring apparatus, at least two unique portions formed on the tape so as to match the predetermined liquid level in the length direction, unique portion detecting means for detecting the unique portions, and at least two unique portions are detected. And the constant changing means for changing the constants D and t based on the output of the rotation detecting means at the time of the detection, so that the two data from the rotation detecting means at the time when each unique part is detected are respectively A conversion signal at a known liquid level is obtained, and two constants D and t can be known, and an accurate liquid amount can be obtained regardless of a change in the diameter D of the drum and a change in the thickness t of the tape due to a temperature change or the like. It can be.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a gas station to which a liquid level measuring device of the present invention is applied.

FIG. 2 is a cross-sectional view showing one embodiment of a mechanism of the liquid level measuring device.

FIG. 3 is a diagram showing one embodiment of a tape connected to a float.

FIG. 4 is a block diagram showing one embodiment of a signal processing unit in FIG. 2;

FIG. 5 is a block diagram illustrating an embodiment of a receiving device.

FIG. 6 is a flowchart showing an operation on the liquid level transmitting device side.

FIG. 7 is a flowchart showing an operation on the receiving device side.

FIG. 8 is a timing chart showing the operation of the above device.

[Explanation of symbols]

 2, 2 Underground tank 3, 3 Liquid level transmitter 6 Receiver 9 Tape drum 10 Float 11 Tape 15, 16 Mark 17 Rotation detector 20 Signal processing circuit 21 Unique part detector 24 Antenna

Claims (1)

(57) [Claims] 1. A tank which winds a tape connected to a float around a drum, and uses an output from a detecting means for detecting rotation of the drum, a diameter D of the drum, and a thickness t of the tape as constants using a relational expression. In the float type liquid level measuring device for measuring the liquid level, at least two unique parts formed corresponding to a predetermined liquid level in the length direction on the tape, and a unique part detecting means for detecting the unique part, A float type liquid level measuring device, comprising: constant changing means for changing the constants D and t based on the output of the rotation detecting means when at least two of the unique portions are detected.