Abstrict A mass flow meter including a fluid volume indicating means for
measuring the volume of a fluid, a temperature sensor for indicating
the temperature of the fluid being measured by the fluid volume
indicating means, a density compensator connected to the volume
indicating means and the temperature means to provide an indication
of mass flow rate of the fluid material, and counting means to accurately
accumulate the indication of mass units to provide the total mass
of the fluid being measured. The signal output of the volume indicating
means and the temperature sensor from the temperature sensor provide
input pulses to the variable pulse width means in the density compensator
to initiate an output measuring envelope pulse and to cut off the
output measuring envelope pulse. The envelope pulse is an input
density compensated envelope pulse to the counting means. The density
compensator includes an oscillator producing a high frequency output
to the counter means. The counter accumulates through the output
of the density compensator the mass flow data to provide an indication
of total mass of the fluid measured.
Claims What is claimed is:
1. A fluid temperature compensation meter comprising;
a fluid volume sensing means to produce a first output pulse signal
for measuring the volume of the fluid to be measured,
a temperature sensor connected adjacent said fluid volume sensing
means to produce a second output signal for measuring the temperature
of the fluid to be measured,
a compensator connected to said fluid volume sensing means to provide
a first input into said compensator and to said temperature sensor
to provide an additional input to said compensator to correct the
measured first input signal to provide liquid mass flow data, said
compensator including an output,
a signaling means connected to said output of said compensator
to indicate the mass of the fluid measured, and
said compensator including a variable pulse width generating means
connected to said fluid volume sensing means to produce pulses in
synchronism with said output pulse signal of said fluid volume sensing
means and connected to said temperature sensor to control the width
of said volume sensing means output pulses to provide density compensating
envelope pulses.
2. A fluid temperature compensation meter as set forth in claim
1 wherein;
said compensator includes an oscillator for producing a cyclic
oscillator pulse output,
a counter connected to said oscillator and to said variable pulse
width generating means to receive controlled density compensating
envelope pulse and the cyclic oscillator pulses for the period of
said density compensating envelope pulse, and
said temperature sensor is a cryogenic sensor and said fluid volume
sensing means is a cryogenic fluid volume sensing means.
3. A fluid temperature compensation meter as set forth in claim
2 wherein;
said temperature sensor including a bridge circuit,
said variable pulse width generating means connected to said bridge
circuit for providing a time varying pulse cutoff signal to vary
the length of the density compensating envelope pulse output for
obtaining accurate mass determination.
4. A fluid temperature compensation meter as set forth in claim
1 including;
a counter means connected to said output of said compensator.
Description BACKGROUND OF THE INVENTION
This invention relates to a new and improved means for determining
the mass of fluid passing through a conduit in a fluid system, and,
more particularly, to a single phase mass rate indicator of a liquid
passing through a particular conduit including a new and improved
density compensator and a counting means.
As is perhaps well known, turbine and other types of volumetric
flow meters have been used to measure the rate of fluid passing
through a conduit. The angular speed of the turbine is determined
by the fluid flow rate, and therefore the angular speed of the turbine
indicates the fluid flow rate. Such volumetric flow meters are calibrated
to read directly in volumetric units. When the fluid being measured
has a constant density, such volumetric flow meters can be calibrated
directly in terms of mass units. When the density is a variable,
the mass units cannot be calculated directly from the angular speed
of a turbine. Most fluids decrease in density as the temperature
increases. Therefore, the mass flow may be obtained by calculating
the volumetric flow, measuring the temperature of the fluid, calculating
the density of the fluid at the particular temperature, and multiplying
the volumetric flow by the ratio of density at the fluid temperature
to the density at a particular reference temperature. The ratio
of the density at the fluid temperature to the density at the reference
temperature is called the density compensation factor.
BRIEF DESCRIPTION OF THE INVENTION
The present invention is related to a new and improved fluid mass
indicator including a density compensator means. The density compensator
means is connected to a fluid volume indicator means for indicating
the fluid volume, and a temperature sensor is placed adjacent said
fluid volume indicator means for indicating the temperature of the
fluid. The fluid volume indicator means and the temperature sensor
provide input signals to the density compensator means. The density
compensator includes an oscillator and a variable pulse width means.
The fluid volume indicator means is connected to the variable pulse
width means to initiate an output envelope pulse. The temperature
sensor is connected to the variable pulse width means to control
the width of the envelope pulse by controlling the shut off point
of the envelope pulse. The output of the variable pulse width means
and the constant cyclic output of the oscillator are connected to
a binary counter to provide the total number of units of mass passing
through the volume flow means. The binary counter counts the cyclic
output of the oscillator during the time the binary counter receives
the envelope pulse.
It is an object of this invention to provide a noncomplex mass
flow meter for measuring a single phase fluid of varying density.
Another object of this invention is to provide a density compensator
means for a fluid volume indicating means and a temperature sensor
means.
Another object of this invention is to provide an efficient battery
operated mass flow meter.
A further object of this invention is to provide a portable mass
flow meter for trucks pumping cryogenic fluids.
In accordance with these and other objects which will be apparent
hereinafter, the instant invention will now be described with particular
reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
In the drawing:
FIG. 1 is a block diagram of the mass flow meter;
FIG. 2 is a side view of a turbine means; and
FIG. 3 is a detailed diagram of the density compensator.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now in detail to the drawing, wherein an embodiment of
the invention is shown, and, referring particularly to FIG. 1 the
mass flow meter, generally designated by numeral 2 includes a fluid
volume indicating means 4 and a temperature sensor 6 in a fluid
conduit 8 connected to a density compensator means 10. The density
compensator means 10 includes a density compensator 11 and counting
means 12. The mass flow meter 2 includes the fluid volume indicating
means 4 for measuring the volume of the fluid passing through conduit
8 the temperature sensor 6 for indicating the temperature of the
fluid being measured by the fluid volume indicating means 4. The
density compensator means 10 is connected to the volume indicating
means 4 and the temperature means 6 to provide an indication of
the mass flow rate of the fluid material. The signal output of the
volume indicating means 4 and the temperature signal from the temperature
sensor 6 provide input pulses to the density compensator 11 to provide
a measuring envelope output pulse and a high frequency output to
the counter means 12. The counter accumulated the mass flow data
in the density compensator outputs to provide an indication of the
total mass of the fluid measured.
The fluid volume indicating means 4 may be any ordinary turbine
meter means 14 as shown in FIG. 2. The volume meter means has turbine
blades 16 connected to shaft 18 supported by members 20 in the conduit
8. The shaft 18 includes a cam 22 that actuates a cam follower 24.
The cam follower 24 triggers the electrical switching means 26.
Switch 26 initiates at least one pulse for each revolution of the
shaft 18. The signal is transferred over line 28 to the density
compensator 11. The temperature sensor 6 produces a signal that
is transmitted over line 30 to the density compensator 11.
The density compensator 11 includes an interface or input filter
means 32 between the fluid volume indicating means 4 and variable
pulse width means 34 in order to initiate the system pulse measuring
envelope pulse, or density compensator envelope pulse as shown at
36. The signal from the fluid volume indicator means 4 initiates
pulse 36 as indicated by numeral 38. The temperature sensor 6 is
connected to a bridge circuit 40 by line 30 having an output connected
to DC preamplifier 42 in order to condition and forward a signal
over line 44 to the variable pulse width means 34. The termination
of pulse 36 as indicated by numeral 46 is therefore controlled by
the temperature signal from sensor 6.
The pulse width of envelope 36 determines the number of oscillator
cycles from oscillator 48 that are accumulated and counted by counting
means 12. The binary counter 50 will produce an output pulse when
a fixed number of cycles have been accumulated within its registers.
The output pulse is forwarded to a second binary counter 52 for
producing an output pulse when a fixed number of pulses from counter
50 have been accumulated within its registers. The output pulse
from counter 52 may be forwarded to additional binary counters.
The output pulse from counter 52 is forwarded to the pulse expander
54. The pulse expander 54 prepares an output pulse to drive counter
drive circuit 56. The counter drive circuit may be used to drive
a numbered dial or printer 58 for visually indicating the mass flow
of fluid through the fluid conduit 8.
Referring now to FIG. 3 the interface 32 includes filter 63 with
a capacitor resistor network connected to the negative terminal
of the battery 60 as indicated by numeral 65. The interface 32 also
includes jack 67. The jack 67 is connected to the fluid volume indicating
means 4 by line 28. Interface 32 is connected to voltage regulators
62 and 64. The battery 60 is also connected across jack terminals
a and b, not shown. The interface 32 is connected to the variable
pulse width means 34 by line 68. The filter 63 is connected to the
multi-vibrator or retriggerable one shot 70. The vibrator 70 is
a triggering means that initiates pulse 36 as shown by numeral 38.
The variable pulse width means 34 also triggers the end the pulse
as shown at 46. The temperature signal from temperature sensor 6
passes through bridge circuit 40 D.C. pre amp 42 over line 44 to
the cutoff trigger means shown at 72. The multivibrator 70 is connected
to the system by connecting the standard terminals 1', 2', 7', 8',
14', 13', and 11' of the multivibrator into the system as illustrated.
The output of the variable pulse width means 34 is connected to
the binary hex decimal counter 50 which is connected into the system
by connecting the standard terminals 10', 16', 1', 15', 8', and
2' of the counter into the system as illustrated. The counter 50
is connected to counter 52 which is similar to counter 50 which
is connected to the voltage regulator shown as an integrated voltage
regulator, a dual inline package, through B. The counters 50 and
52 and the multivibrator 74 are connected through a resistor, not
shown, to the battery through B. Terminals 11' and 13' of the multivibrator
74 are connected to timing circuit 76. The multi-vibrator is connected
to the counter drive circuit 56 which includes the NPN drive transistor
78. The counter drive circuit 56 is connected to printer 58 that
is connected to battery 60 at A.
The temperature sensor 6 including resistor means 80 is connected
to jack 82. Jack 82 is connected to the matching jack 84 that connects
resistor 80 into the bridge circuit 40. Jack 84 is also connected
to a common ground such as a floating ground at 92. Resistors 80
86 88 and 90 are interconnected, as shown, to form bridge circuit
40. The output of the bridge cricuit 40 is connected to the DC preamplifier
42 that includes an integrated circuit operational amplifier 94.
A manual preset variable resistor 96 is included to allow adjustment
of the device for determining mass of various types of liquid materials.
The amplifier 94 is connected to the voltage regulator shown as
an integrated voltage regulator, that is, a dual inline package
98. The jack mark A is connected to the battery 60. The driver transistor
100 is a PNP type.
The oscillator 48 is connected to the binary counter 50 in the
binary counter 12. The oscillator 48 is connected to the floating
DC power supply 66 including NPN drive transistor and a transformer.
The floating DC power supply 66 is connected to voltage regulator
64 and to the bridge circuit 40.
For successful operation of the meter under environmental and physical
conditions encountered in truck delivery of cryogenic materials,
the supply voltage parameter is .+-. 4.5 volts in order to operate
off a standard 12 volt battery. In order to operate, when the input
signal is from a bridge circuit, there must be high input impedance,
differential input, high common mode and normal mode rejection,
an input offset voltage less than 1 millivolt, and input offset
current less than 1 nanoampere. To operate over extreme temperature
conditions, the following parameters must be met; capacity of operating
over a temperature range of 55.degree.C to + 125.degree.C, average
temperature coefficient of input offset voltage less than 5 microvolts
per centigrade, and average temperature coefficient of input offset
current less than 10 picoamperes per centigrade.
It should be noted that the integrated circuit operational amplifier
94 may be Raytheon unit Number RM 4132DI.
The instant invention has been shown and described herein in what
is considered to be the most practical and preferred embodiment.
It is recognized, however, that departures may be made therefrom
within the scope of the invention and that obvious modifications
will occur to a person skilled in the art. |