JPH0258418B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid storage device for storing fluid in a tank, and more particularly to a device for measuring the amount of fluid in a tank.

2. Description of the Related Art As a fluid storage device, one shown in FIGS. 1 to 3 has been proposed, for example, for a human waste collection truck called a vacuum car. In the figure,
1 is a tank loaded on a pumping truck, 2 is a pump that reduces the pressure inside the tank, and 3 is a suction valve consisting of a solenoid valve connected to the bottom of tank 1, which is normally closed and when tank 1 is depressurized. The tank 1 is opened to the tank 1, and human waste from a toilet tank (not shown) in each household is sucked into the tank 1 through an external hose (not shown). Reference numeral 4 indicates a fluid consisting of human waste stored in the tank 1 via the suction valve 3, 5 indicates a discharge valve consisting of an electromagnetic valve provided at the bottom of the tank 1, and 6 measures the top pressure within the tank 1 and outputs a signal P ₀ 7 is a bottom pressure gauge that measures the bottom pressure in tank 1 and outputs signal _P1 , 8 is an operation panel that operates the pumping and discharging of human waste 4, and is operated when pumping starts. a start button 81 that operates the pump 2 and opens the suction valve 3.
and an end button 8 which is operated at the end of pumping to stop the pump 2 and close the suction valve 3.
2, and a total amount button 83 for instructing to calculate the total amount of human waste 4 in the tank 1.
11 is a pressure difference signal P ₁ −P ₀ obtained by subtracting the output signal P ₀ of the top pressure gauge 6 from the output signal P ₁ of the bottom pressure gauge 7
A pressure subtractor 12 outputs this pressure subtractor 1.
1 is a signal converter that converts the pressure difference signal P ₁ -P ₀ from an analog signal to a digital signal; 13 is a first register that stores the output signal D _S of the signal converter 12 when the start button 81 is pressed; and 14 is the output signal of the signal converter 12 when the end button 82 is pressed.
A second register for storing D _L , 15 is the output signal of the signal converter 12 when the total amount button 83 is pressed.
16 is a third register for storing D _T , 16 is a first conversion means for outputting a volume signal V _S for the output signal D _S of the first register 13 based on the relationship between pressure and volume shown in FIG. Similarly, the second register 1
A second conversion means outputs a volume signal V _L for the output signal D _L of 4, and 18 is a third register 15
A third conversion means 19 outputs _a volume signal V _T in response to _an output signal D _T of a subtractor outputting _L −V _S , 20
is a printer that prints out the pumped volume signal V _L -V _S and the volume volume signal V _T.

Next, the operation of the fluid storage device configured as described above will be explained.

First, when collecting human waste 4, the user presses the start button 81 after connecting the toilet tank and tank 1 via an external hose. Pressure difference signal P ₁ − of pressure subtractor 11
P ₀ indicates the bottom pressure signal of the tank 1 due to the human waste 4, and by operating the start button 81, the output signal D _S corresponding to before pumping is stored in the first register 13, and further, the output signal D S is stored in the first converting means 16. Therefore, it is converted into a volumetric signal V _S. When the pumping is finished, the end button 82 is pressed, the suction valve 3 is closed, and the pump 2 is also stopped. The pressure difference signal P ₁ −P ₀ of the pressure subtractor 11 indicates the value after pumping out the human waste 4, and by pressing the end button 82, the output of the signal converter 12 corresponding to the total amount after pumping signal
D _L is stored in the second register 14, and furthermore, the second
The conversion means 17 converts it into a volumetric signal V _L . The subtractor 19 outputs the amount signal V _L −V _S , which is printed out by the printer 20 together with the signal from the end button 82 .

Furthermore, when the total amount button 83 is pressed, the output signal D _T of the signal converter 12 corresponding to the total amount of human waste 4 in the tank 1 is stored in the third register 15, regardless of whether pumping is in progress or stopped. The third conversion means 18 outputs the volume signal V _T and the total volume button 83
The signal is printed out by the printer 20 together with the signal.

In this way, it is possible to collect fees from each household based on the printed out amount of collected waste, and also to know the total amount of human waste 4 in the tank 1 and the remaining storage capacity.

However, in the above-mentioned fluid storage device, the top pressure gauge 6 and the bottom pressure gauge 7 in particular may drift due to temperature or the like, and an accurate pumped amount may not be printed out. That is, tank 1
is a horizontal columnar body with an elliptical cross section.
The relationship between the pressure signal and the volume signal due to human waste 4 is as shown in FIG. Now, the remaining human waste before being pumped out is measured by the top pressure gauge 6 and the bottom pressure gauge 7, and the output signal D _S1 is output from the first register 13. If the output signal D _S2 , which is larger by d, is output because of the drift of the human waste 4, the volume signal of the human waste 4, which should be output as V _S1 , will be output as V _S2 . In this state where the drift remains by d, the pressure at the end of pumping is measured, and an output signal is output from the second register 14.
If an output signal D _L2 that is larger by d is output when D _L1 should be output, the volume signal of human waste 4 will be output as V _L2 instead of V _L1 . Here, since the tank 1 is oval, the influence of the drift d on the volume is as follows:
As shown in FIG. 3, the largest volume error appears when almost half of the human waste 4 is stored in the tank 1. Therefore, the measured pumping volume V _L2
−V _S2 will be greater than the actual pumped volume V _L1 −V _S1 and a fee will be charged for that larger value. In this way, particularly accurate measurements are required when the tank 1 is oval.

In addition, if the tank 1 has a rectangular hollow cross section, the pressure and volume will increase linearly, so
In the amount of pumping obtained as the difference between the two measured values, the error due to drift is canceled out and has no effect, but an error occurs in the total amount. For this reason, it is expected that there will be problems such as over-filling or stopping pumping because the tank is full even though there is still room.

This invention was made in view of the above drawbacks,
When measuring the liquid level or pressure of liquid stored in a tank using a measuring means and calculating the volume from this measured value, the output signal of the measuring means when a known amount of fluid is stored in the tank and this known A reference signal corresponding to the quantity is subtracted to obtain a correction signal, and the output signal of the measuring means is corrected with this correction signal, thereby eliminating measurement errors due to drift of the measuring means and, by extension, preventing disputes due to measurement errors. The purpose of this is to perform accurate measurements without the need for

4 and 5 show an embodiment of the present invention. In the figures, 30 is provided at the bottom of the tank 1, and when the human waste 4 is stored in a predetermined known amount, the liquid level of the human waste 4 is The reference position detecting means 31 generates a pulse signal only at the instant of activation by the reference position detecting means 31, which is set in advance as a signal corresponding to the hydraulic pressure generated at the bottom pressure gauge 7 when the known amount of human waste 4 is stored. A reference signal generator 32 generates a reference signal D ₀ and output signal D measured by the top pressure gauge 6 and bottom pressure gauge 7 and converted into a digital signal by the converter 12 and the reference signal D _{0 .}
A correction means 33 outputs a difference signal D-D ₀ of the correction means 32 when the pulse signal of the reference position detection means ₃₀ is outputted as a correction signal d.
A fourth register 34 stores the converter 12 as
This correction means subtracts the correction signal d from the output signal D of and outputs the correction signal D−d.

In the fluid storage device configured as described above, a known amount of human waste 4 is already stored in the tank 1 prior to pumping, and the correction means 32
It is assumed that a correction signal d is output from.
It is assumed that the correction signal d is stored in the fourth register 33 by the pulse signal of the reference position detection means 30. When the start button 81 is pressed in this state, the human waste 4 is transferred to the tank 1 in the same way as in the case of FIG.
At the same time, the output signal D _S before being pumped is
The corrected signal D _S −d obtained by correcting the correction signal d is the first
stored in the register 13 and further stored in the first conversion means 16
is converted into a volumetric signal _VS. As human waste 4 is being collected, one time's worth of collection is completed.
End button 82 is pressed. At this time, a correction signal D _L -d obtained by correcting the output signal D L after the completion of pumping with the correction signal _d is stored in the second register 14, and further, the second converting means 17 It is converted into a signal V _L. The volume signal V _L and the volume signal V _S are subtracted by a subtractor 19 to obtain the pumped amount.
V _L -V _S , and together with the signal from the end button 82, the printer 20 prints out the signal.

Further, in order to display the total volume of human waste 4 in the tank 1, the total volume button 83 is pressed. As a result, a correction signal D T -d obtained by correcting the output signal V _T for the human waste 4 in the tank 1 at that time by the correction signal _d is stored in the third register 15, and further, the third converting means 18
It is converted into a volume signal V _T and printed out from the printer 20.

According to the above embodiment, when a known amount of human waste 4 is stored in the tank 1, this known amount is measured by the top pressure gauge 6.
and a reference signal preset in correspondence with the signal D obtained by measuring with the bottom pressure gauge 7 and a known quantity.
A correction signal d is calculated from D ₀ , and the signal D obtained by measuring with the top pressure gauge 6 and the bottom pressure gauge 7 is corrected using this correction signal d and then changed to a volume signal. For example, as shown in FIG. Even if the measured signals D _S2 and D _L2 contain an error from the accurate signals D _S1 and D _L1 due to drift, they are corrected with a correction signal d corresponding to this error. hand,
Accurate signals D _S1 and D _L1 are obtained, allowing highly accurate measurement.

In addition, according to the above embodiment, it is assumed that a predetermined amount of human waste is stored in the tank 1 as a known amount, but the signal obtained from the pressure gauge when the tank is empty is stored in a register and also used as a correction signal. It's good. In this case, since it can be easily detected that the tank is empty by opening the discharge valve, there is no need for any particular device to detect that the tank is empty. Furthermore, since the inside of the tank is empty, there is no need to provide a reference signal generating means.

It is clear that the present invention can also be applied to measuring the liquid level of human waste in a tank and calculating the volume of human waste appropriate to the shape of the tank from this liquid level.

Furthermore, the present invention is not limited to human waste, but can be applied to fluids in general.

As explained above, this invention measures the liquid level or pressure of this fluid with a measuring means when a known amount of fluid is stored in a tank, and makes the output signal of the measuring means at this time correspond to the known amount. , a preset reference signal is input to the correction means to output a correction signal, and the output signal of the measurement means is corrected with this correction signal, and then converted to a volume signal by the conversion means, so that seasonal temperature changes can be avoided. Even if the measurement result by the measurement means contains an error caused by drift, etc., it can be removed and the volumetric amount can be obtained with high accuracy.

[Brief explanation of the drawing]

1 to 3 show a fluid storage device which is the premise of this invention, FIG. 1 is a perspective view showing its configuration, FIG. 2 is a block diagram of a measuring circuit, FIG. 3 is an explanatory diagram, and FIG. 5 and 5 show one embodiment of the present invention, FIG. 4 is a perspective view showing its configuration, and FIG. 5 is a block diagram of the measuring circuit. In the figure, 1 is a tank, 4 is a fluid, 6 is a top pressure gauge (measuring means), 7 is a bottom pressure gauge (measuring means), 16 is a first conversion means (conversion means), 17 is a second conversion means (conversion means) 18 is a third conversion means (conversion means), 32 is a correction means, and 34 is a correction means. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A tank for storing a fluid, a measuring means for measuring the liquid level or pressure of the fluid stored in the tank, and an output of the measuring means when a known amount of fluid is stored in the tank. a correction means for outputting a correction signal from the signal and a reference signal set in advance in correspondence with the known quantity; a correction means for correcting the output signal of the measurement means with the correction signal of the correction means;
A fluid storage device comprising conversion means for converting the output signal of the modification means into a volumetric quantity. 2. The fluid storage device according to claim 1, further comprising a correction means that uses an output signal of the measurement means when there is no fluid in a portion corresponding to the measurement means as a correction signal.