CA1301476C - Flow metering device - Google Patents
Flow metering deviceInfo
- Publication number
- CA1301476C CA1301476C CA000542781A CA542781A CA1301476C CA 1301476 C CA1301476 C CA 1301476C CA 000542781 A CA000542781 A CA 000542781A CA 542781 A CA542781 A CA 542781A CA 1301476 C CA1301476 C CA 1301476C
- Authority
- CA
- Canada
- Prior art keywords
- probe
- tube
- liquid
- flow rate
- microprocessor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01C—PLANTING; SOWING; FERTILISING
- A01C15/00—Fertiliser distributors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/007—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring the level variations of storage tanks relative to the time
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
- G01F25/0092—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume for metering by volume
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
- G01F25/10—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of flowmeters
- G01F25/17—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of flowmeters using calibrated reservoirs
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Soil Sciences (AREA)
- Environmental Sciences (AREA)
- Measuring Volume Flow (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An apparatus for measuring the flow rate of conductive aqueous solutions of agricultural chemicals from a nozzle includes a pair of vertical tubes interconnected near their bottom ends by a horizontal tube, a first probe in the bottom of one tube for receiving solution connected to a nine volt battery, a starter probe near the bottom of the other tube for starting operation of a microprocessor when the liquid completes a circuit between the first two probes, and low, medium and high probes in such other tube which are successively contacted by the liquid, so that the microprocessor and an attached read only memory can determine the flow rate based on the time required to fill such other tube and the volume of the tube between. the probes. The tubes can be emptied to reset the apparatus for, another flow rate determination.
An apparatus for measuring the flow rate of conductive aqueous solutions of agricultural chemicals from a nozzle includes a pair of vertical tubes interconnected near their bottom ends by a horizontal tube, a first probe in the bottom of one tube for receiving solution connected to a nine volt battery, a starter probe near the bottom of the other tube for starting operation of a microprocessor when the liquid completes a circuit between the first two probes, and low, medium and high probes in such other tube which are successively contacted by the liquid, so that the microprocessor and an attached read only memory can determine the flow rate based on the time required to fill such other tube and the volume of the tube between. the probes. The tubes can be emptied to reset the apparatus for, another flow rate determination.
Description
~3~
This invention relates to an apparatus for measuring the flow rate of a liquid, and in particular to an apparatus for measuring the flow rate of an electrically conductive liquid.
The apparatus is specifically designed for measuring the flow rate of aqueous solutions of agricultural chemicals, so that the quantity of chemical applied over a given area can be accurately calculated. Agricultural chemicals may be hazardous to the user and to the environment. In order to avoid crop injury or poor performance because of the application of incorrect quantities of chemical, it is important that the flow rate of a crop sprayer be accurately determined. Existing flow measuring devices are unduly complicated, often inaccurate and may include moving parts.
The object of the present invention is to overcome the above-mentioned problems by providing a relatively simple, compact apparatus for accurately measuring the flow rate of an electrically conductive liquid.
Accordingly, the present invention relates to an apparatus for measuring the flow rate of an electrically conductive liquid comprising container means for receiving a predetermined quantity of a flowing liquid; electrical power supply means; computer means connected to said power supply means; first probe means for initiating operation of the apparatus when liquid flowing into said container means 13C~1476 closes a circuit between said first probe means, said power supply means and said computer means; second probe means connected to said computer means, whereby when the liquid closes a circuit between said first and second probe means, the computer means can determine the flow rate based on the volume of said container means and the time required to close the circuit between said first and second probe means; and display means connected to said computer means for providing a visual indication of the flow rate.
The invention will be described in greater detail with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention, and wherein:
Figure 1 is a schematic, exploded, perspective view of a container for use in the apparatus of the present invention;
Figure 2 is a schematic block diagram of an electrical circuit used in the apparatus of the present invention;
Figure 3 is a detailed circuit diagram of the electrical circuit of Fig. 2; and Figure 4 is a block diagram illustrating the manner in which the components of Fig. 3 are to be arranged to form a complete drawing.
It should be noted that in order to simplify illustration of the invention parts have been omitted from the drawings, particularly from Figure 2.
With reference to Fig. 1, one of the basic components of the apparatus of the present invention includes a casing 100 defined by a bottom wall 101, a top wall 102, a rear wall 103, side walls 105 and a front cover plate 106.
An opening 107 is provided in the cover plate 106. The opening 107 is closed by a window 108, which covers a liquid crystal display 110, which is mounted on a plate 111. The plate 111 also carries the remaining circuitry (Figs. 2 and 3), and a power supply, i.e. batteries 112 (Figs. 2 and 3) are mounted in the casing.
The casing 100 houses a container generally indicated at 114. The container 114 is defined by a pair of parallel tubes 116 and 117, which extend upwardly through openings 118 in the top wall 102 of the casing 100. One of the tubes 116 is longer than the other tube 117, extending upwardly beyond the top wall 102.
A first probe 120 (Figs. 2 and 3) extends into the bottom end of the tube 116. Four additional probes 122, 123, 124 and 125 extend into the tube 117. The bottom ends of the tubes 116 and 117 are connected by a horizontal tube 127.
Referring to Fig. 2, the probes 120 and 122 to 125 are incorporated into a circuit including a power supply defined by the batteries 112 (Fig. 3). The batteries 112 are used to provide power to the remaining elements of the .
:
-13~1476 circuit, even though the appropriate connecting lines have been omitted from Fig. 2. This feature of the invention is described in greater detail hereinafter. The probes 123 to 125 are connected to a microprocessor 129, which is controlled by a pair of selector switches 130 and 131, and a tri-state buffer 132. The microprocessor 129 is connected through a latch 134 to a memory (ROM) 135. The microprocessor 129 is also connected to a display driver 137 and the liquid crystal display 110. Voltage from the batteries 112 to the various components of the circuit including the display driver 137 is controlled by a voltage regulator 138.
The operation of the apparatus will be described with reference to Fig. 3. In general terms, the purpose of the apparatus is to measure the flow rate of an agricultural chemical through sprayer nozzles. A mathematical combination of the predetermined volume of the container 114, and the length of time required to fill the volume between the probes 123, 124 and 125 is used to determine the flow rate. By entering the spacing between ad~acent nozzles and the travelling speed of the sprayer, using the switches 130 and 131, respectively, the apparatus can be used to determine the quantity of liquid per unit area.
Power for the apparatus is provided by two nine volt batteries 112, which are connected to two diodes 140. The .
13~)1476 diodes 140 protect the circuit of Fig. 3 from reverse power connection. The negative terminals of the batteries 112 are connected to ground by line 141. The power and logic levels from the ground line 141 to the chips defining the microprocessor 129, the buffer 132, the latch 134, the memory 135, hex buffers 143 for the probes, and the display driver 137 are as follows: pins 7 and 20 of the microprocessor 129;
pin 10 of the buffer 132; pins 1 and 10 of the latch 134;
pins 2, 14 and 22 of the memory 134; pin 8 of the hex buffer 143 and pin 1 of the display driver 137. The nine volt positive power line extends from the diode 140 to the nine volt probe 120 in the tube 116. The nine volt positive power line also supplies power to the hex buffer 143 and the emitter of a switching transistor 145. -As water or an aqueous solution of a chemical is introduced into the longer tube 116, the water flows through the tube 127 into the tube 117. Thus, the water contacts both the start probe 122 and the nine volt probe which causes current to flow through resistors 146 and 147 to ground. The potential at the pin 7 of the buffer 143 is raised sufficiently to drive the output pin 6 to a high potential.
The high potential causes current to flow through diode 149 to charge a capacitor 150 to a high potential. A capacitor 152 connected to the resistor 146 of the start probe 122 is connected from the pin 7 of the buffer 143 to ground to help reduce "noise" on the input of the circuit. From the high potential at pin 6 of the buffer 143 sufficient current flows through the diode 149 to overcome the draining effect of a resistor 153. The high potential then causes current to flow S through a resistor 154 to drive the potential at pin 5 of the buffer 143 high, which in turn drives the output pin 4 high.
The current from the high potential then flows through a resistor 156 to the base of a switching transistor 157, and through the emitter of the transistor to ground. With the extra current flowing through the base of the transistor 157, the internal resistance from the collector to the emitter of the transister is reduced which allows more current to flow from the nine volt supply line through the transistor 145, a resistor 158 and the transistor 157 to ground. The extra current through the base of the transistor 145 allows the resistance between the collector and emitter of the transistor to be greatly reduced which permits the current from the nine volt supply to flow into the emitter of the transistor 157 and through the collector thereof to the input of the voltage regulator 138.
With the input voltage at seven volts or higher and the ground pin of the voltage regulator 138 connected to ground, the voltage regulator will provide a steady five volt supply relative to the ground line. The five volt supply is connected to the pins 5, 6, 26 and 40 of the microprocessor 13~147~;
129, pin 20 of the buffer 132, pin 20 of the latch 134, pins 1, 27 and 28 of the memory 135, and pin 20 of the display driver 137 for supplying power to the chips and to the logic control on some of the chips.
When water is removed from the measuring container 114, i.e. when the tubes 116 and 117 are tilted to empty them, current flow from the nine volt probe 120 to the start probe 122 is cut, and the small charge on the capacitor 152 drains to ground through the resistor 147 in milliseconds or less. With the resistor 147 holding the pin 7 of the buffer 143 low, the output pin 6 of the buffer 143 is also low.
With the diode 149 blocking reverse flow from the charged capacitor 150, the charge and voltage will slowly drain through the resistor 153 to ground with some flow through the 15 resistor 154 and the buffer 143 to ground. The charge on the capacitor 150 remains high enough to keep the pin 5 of the buffer 143 in the "high" input state and therefore maintains power for approximately forty to fifty seconds. In other words, the display still provides a reading even after the container 114 has been emptied.
When water introduced into the container 114 passes the start probe 122 and reaches the low probe 123, current flows through the nine volt probe 120 and the water to the low probe 123. The current then flows from the low probe 123 25 and through resistors 160 and 161 to ground. A capacitor 163 connected from pin 14 of the buffer 143 to ground is intended to reduce the input noise. With current flowing through the resistors 160 and 161, the potential at the pin 14 of the buffer 143 is sufficiently high to drive the output pin 15 on the buffer to a high potential. With a high potential at pin 115 of the buffer 143, current will flow through a resistor 164 to pin 35 of the microprocessor 129, and will change the input pin 35 from a low potential to a high potential. A
pull down resistor 164(a) reduces the high potential level at the pin 35 to an acceptable level and helps produce the low level input.
When the water level rises to the middle or medium probe 124, current flows from the nine volt probe 120 through the water to the medium probe 124, and through resistors 166 and 167 to ground. A capacitor 168 connected from pin 11 of the buffer 143 to ground is intended to reduce the input noise. With current flowing through the resistors 166 and 167, the potential at pin 11 of the buffer 143 is sufficiently high to drive the output pin 12 of the buffer 143 to a high potential. With the high potential at the pin 12, the current flows through a resistor 170 to pin 36 of the microprocessor 129, changing the input pin 36 from a low potential to a high potential. A pull down resistor 170(a) reduces the high potential level at the pin 36 to an acceptable level and helps reduce the low level inputs.
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When the water level reaches the high probe 125, current flows through the nine volt probe 20 and the water to the high probe 125. The current then flows from the high probe 125 through resistors 171 and 172 to ground. A
capacitor 174 connecting pin 9 of the buffer 143 to ground is intended to reduce the input noise. With current flowing through the resistors 171 and 172, the potential at the pin 9 of the buffer 143 is sufficiently high to drive the output pin 10 of the buffer 143 to a high potential. With a high potential at pin 10 of the buffer 143, the current will flow through a resistor 175 to pin 37 of the microprocessor 129, changing the input pin 37 from a low potential to a high potential. A pull down resistor 175(a) reduces the high potential level at the pin 37 to an acceptable level and reduces low level input.
The switch 130 is a binary coded decimal (BCD) switch connected to the octal tri-state buffer 132, with pull down resistors 177 on outputs 1, 2, 4 and 8. Pins labelled "c" are connected to the five volt supply. When the switch 130 is rotated from the 0 to the 9 position, the output from pins 1, 2, 4 and 8 will change states from high to low and low to high to give an e~uivalent output from the switch.
The output pins 1, 2, 4 and 8 are connected to pins 11, 13, 15 and 17, respectively of the buffer 132. The same switch setup is used for the selector switch 131, except that the pull down resistors 178 and the output pins 1, 2, 4 and 8 are connected to pins 2, 4, 6 and 8, respectively of the buffer 132. The switches 130 and 131 are selector switches for speed and spacing inputs to the buffer 132. The speed in question is the speed of travel of the sprayer, and the spacing is the spacing between the sprayer nozzles.
When the speed spacing values are to be read by the microprocessor 129, a high level input is sent from the buffer 132 to the pin 31 of the microprocessor 129 which is in a normally low state, as is the other data select ouput pin 32. When both pins 31 and 32 are in the low state, pins 1 and 19 of the buffer 132 are in the low state, and drive the output pins 3, 5, 7, 9, 18, 16, 14 and 12 into a high impedance. When the pin 31 of the microprocessor 129 goes to 15 a high state, it drives the pin 19 of the buffer 132 to a high state, permitting the data at pins 11, 13, 15 and 17 to appear on pins 3, 5, 7 and 9 of the buffer 132. When the pin 32 of the microprocessor 129 goes high, it drives pin 1 of the buffer 132 high, permitting data on the pins 2, 4, 6 and 20 8 to appear on pins 18, 16, 14 and 12, respectively of the buffer 132.
When the current from the five volt supply line runs through a resistor 180 and a zener diode 181, the voltage at battery drops because of discharge, the supply voltage to the buffer 143 also drops while the voltage at the pin 3 of the .
' . , .
130~76 buffer 143 remains relatively constant. With a drop in supply voltage, the high/low threshold also drops and passes the voltage at pin 3 of buffer 143. Thus, the output pin 2 of the buffer 143 goes to a high state which in turn drives pin 1 of the microprocessor 129 into a high state through resistor 182. A resistor 184 connected to ground helps reduce the voltages at pin 1 to acceptable levels.
Additional switches 186 are connected to input pins 33, 34, 38 and 39 of the microprocessor 129 to pull the input pins from their naturally high states to low states. The switches 186 are opened or closed to make four different selections, namely high or low speed range, high or low spacing range, large or small tube size, and English or metric units.
The memory 135 is a read only memory (ROM) chip containing a program for the microprocessor 129. The data lines from the microprocessor 129 (pins 12 to 19) are connected to pins 11 to 13 and 15 to 19, respectively of the memory 135. The pins 12 to 19 are also connected to the pins 3, 4, 7, 8, 13, 14, 17 and 18, respectively of the latch 134. The latch 134 is a tri-state octal latch. The output lines from the latch 134 which are address lines appear on pins 2, 5, 6, 9, 12, 15, 16 and 19 and are connected to pins 10, 9, 8, 7, 6, 5, 4 and 3, respectively of the memory 135.
Four port line pins 21 to 24 of the microprocessor 129 are -- 11 -- \
13~76 connected to the top address pins 25, 24, 21 and 23, respectively of the memory 135. The "ALE" line on pin 12 of the microprocessor 129 is connected to the enable line of the latch pin 11 of the latch 134. The "PSEN" pin 9 of the microprocessor 129 is connected to the "CS" pin 20 of the memory 135. With this arrangement, the microprocessor 129 can read the program from the memory 135.
By using the following connections, the microprocessor clock can function and run the program: a capacitor 186 is connected to ground and to pin 2 of the microprocessor 129, a capacitor 187 is connected to ground and to pin 3 of the microprocessor 129, and crystal 188 is connected to pins 2 and 3 of the microprocessor. A capacitor 190 is a reset capacitor, which permits the microprocessor to reset internal registers before a program starts to run. For data to be transmitted from the microprocessor 129 to the display driver 137, the pins 21, 22 and 25 of the latter must be connected to pins 10, 12 and 24, respectively of the microprocessor 129. The pin connections illustrated in Fig.
3 between the display driver 137 and the display 110 enable the driver to operate the display. A capacitor 191 connected to ground and to pin 19 of the driver 137, and a resistor 192 connected to the five volt supply and to pin 19 of the driver 137 set up the oscillator which operates the driver 137.
When power is applied to the microprocessor 129 , ~' .
' 13~1~76 using the automatic turn-on circuitry described hereinbefore, the microprocessor immediately proceeds through the program stored in the memory 135. The program automatically monitors the input from the probe buffers 143 and the selector switches 130 and 131, and when given correct sequence of events, mathematically determines the flow rate by using variables determined by the user, including speed and spacing, a unit of time determined by the microprocessor and the predetermined volume of the tube.
When the microprocessor 129 detects a change in the low buffer input, a timer/counter within the microprocessor is started. The timer continues counting as the container 114 fills with water until a change in the output of the medium probe 124 is detected. When the change is detected, the value of the counter is stored in the microprocessor 129 and the computer continues to count until a change in the high probe 125 is detected or an overcount occurs. When a change in the high probe 125 is detected, the count stops and the count values are stored in the microprocessor 129. For an overcount with a medium probe count value, and because the medium probe position is one-half the high probe position, the count is stopped and the count value is doubled and stored in the memory. For an overcount with no probe changes on the medium or high probe, the count is stopped and the microprocessor 129 outputs an overcount display to the liquid , , ' 13~i~7~i crystal display 110.
The microprocessor 129 then examines the switch positions and determines the values for the speed, spacing, tube size and units for the display, the microprocessor 129 then determines the exact flow rate or application rate from the variables of speed, spacing, time measured, units required and the volume of the tube between the probes. When the microprocessor 129 has calculated the displayed value, such value is displayed on the liquid crystal display 110 with the units indicator. The indicators are displayed to show the units used. If an out of range display is calculated, the indicators change to show that the display drive unit is out of the predetermined operating range of the nozzle checker (the apparatus of the present invention). The calculated value will remain on the display 110 until the microprocessor 129 detects a low state on the low buffer 143, i.e. on the low probe 122. This is effected by dumping water out of the tubes 116 and 117. The microprocessor 129 will also reset the timer and clear the display 110 to ready the apparatus for testing another nozzle.
Finally, the microprocessor 129 will wait until the automatic shut-off circuit turns the power off in about forty to fifty seconds if there has been no change in the start probe input. The hex buffer 143 and the associated sensing circuit are the only components that are left on. In this ~3~76 "off" mode the batteries 112 should last approximately one to one and one-half years.
This invention relates to an apparatus for measuring the flow rate of a liquid, and in particular to an apparatus for measuring the flow rate of an electrically conductive liquid.
The apparatus is specifically designed for measuring the flow rate of aqueous solutions of agricultural chemicals, so that the quantity of chemical applied over a given area can be accurately calculated. Agricultural chemicals may be hazardous to the user and to the environment. In order to avoid crop injury or poor performance because of the application of incorrect quantities of chemical, it is important that the flow rate of a crop sprayer be accurately determined. Existing flow measuring devices are unduly complicated, often inaccurate and may include moving parts.
The object of the present invention is to overcome the above-mentioned problems by providing a relatively simple, compact apparatus for accurately measuring the flow rate of an electrically conductive liquid.
Accordingly, the present invention relates to an apparatus for measuring the flow rate of an electrically conductive liquid comprising container means for receiving a predetermined quantity of a flowing liquid; electrical power supply means; computer means connected to said power supply means; first probe means for initiating operation of the apparatus when liquid flowing into said container means 13C~1476 closes a circuit between said first probe means, said power supply means and said computer means; second probe means connected to said computer means, whereby when the liquid closes a circuit between said first and second probe means, the computer means can determine the flow rate based on the volume of said container means and the time required to close the circuit between said first and second probe means; and display means connected to said computer means for providing a visual indication of the flow rate.
The invention will be described in greater detail with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention, and wherein:
Figure 1 is a schematic, exploded, perspective view of a container for use in the apparatus of the present invention;
Figure 2 is a schematic block diagram of an electrical circuit used in the apparatus of the present invention;
Figure 3 is a detailed circuit diagram of the electrical circuit of Fig. 2; and Figure 4 is a block diagram illustrating the manner in which the components of Fig. 3 are to be arranged to form a complete drawing.
It should be noted that in order to simplify illustration of the invention parts have been omitted from the drawings, particularly from Figure 2.
With reference to Fig. 1, one of the basic components of the apparatus of the present invention includes a casing 100 defined by a bottom wall 101, a top wall 102, a rear wall 103, side walls 105 and a front cover plate 106.
An opening 107 is provided in the cover plate 106. The opening 107 is closed by a window 108, which covers a liquid crystal display 110, which is mounted on a plate 111. The plate 111 also carries the remaining circuitry (Figs. 2 and 3), and a power supply, i.e. batteries 112 (Figs. 2 and 3) are mounted in the casing.
The casing 100 houses a container generally indicated at 114. The container 114 is defined by a pair of parallel tubes 116 and 117, which extend upwardly through openings 118 in the top wall 102 of the casing 100. One of the tubes 116 is longer than the other tube 117, extending upwardly beyond the top wall 102.
A first probe 120 (Figs. 2 and 3) extends into the bottom end of the tube 116. Four additional probes 122, 123, 124 and 125 extend into the tube 117. The bottom ends of the tubes 116 and 117 are connected by a horizontal tube 127.
Referring to Fig. 2, the probes 120 and 122 to 125 are incorporated into a circuit including a power supply defined by the batteries 112 (Fig. 3). The batteries 112 are used to provide power to the remaining elements of the .
:
-13~1476 circuit, even though the appropriate connecting lines have been omitted from Fig. 2. This feature of the invention is described in greater detail hereinafter. The probes 123 to 125 are connected to a microprocessor 129, which is controlled by a pair of selector switches 130 and 131, and a tri-state buffer 132. The microprocessor 129 is connected through a latch 134 to a memory (ROM) 135. The microprocessor 129 is also connected to a display driver 137 and the liquid crystal display 110. Voltage from the batteries 112 to the various components of the circuit including the display driver 137 is controlled by a voltage regulator 138.
The operation of the apparatus will be described with reference to Fig. 3. In general terms, the purpose of the apparatus is to measure the flow rate of an agricultural chemical through sprayer nozzles. A mathematical combination of the predetermined volume of the container 114, and the length of time required to fill the volume between the probes 123, 124 and 125 is used to determine the flow rate. By entering the spacing between ad~acent nozzles and the travelling speed of the sprayer, using the switches 130 and 131, respectively, the apparatus can be used to determine the quantity of liquid per unit area.
Power for the apparatus is provided by two nine volt batteries 112, which are connected to two diodes 140. The .
13~)1476 diodes 140 protect the circuit of Fig. 3 from reverse power connection. The negative terminals of the batteries 112 are connected to ground by line 141. The power and logic levels from the ground line 141 to the chips defining the microprocessor 129, the buffer 132, the latch 134, the memory 135, hex buffers 143 for the probes, and the display driver 137 are as follows: pins 7 and 20 of the microprocessor 129;
pin 10 of the buffer 132; pins 1 and 10 of the latch 134;
pins 2, 14 and 22 of the memory 134; pin 8 of the hex buffer 143 and pin 1 of the display driver 137. The nine volt positive power line extends from the diode 140 to the nine volt probe 120 in the tube 116. The nine volt positive power line also supplies power to the hex buffer 143 and the emitter of a switching transistor 145. -As water or an aqueous solution of a chemical is introduced into the longer tube 116, the water flows through the tube 127 into the tube 117. Thus, the water contacts both the start probe 122 and the nine volt probe which causes current to flow through resistors 146 and 147 to ground. The potential at the pin 7 of the buffer 143 is raised sufficiently to drive the output pin 6 to a high potential.
The high potential causes current to flow through diode 149 to charge a capacitor 150 to a high potential. A capacitor 152 connected to the resistor 146 of the start probe 122 is connected from the pin 7 of the buffer 143 to ground to help reduce "noise" on the input of the circuit. From the high potential at pin 6 of the buffer 143 sufficient current flows through the diode 149 to overcome the draining effect of a resistor 153. The high potential then causes current to flow S through a resistor 154 to drive the potential at pin 5 of the buffer 143 high, which in turn drives the output pin 4 high.
The current from the high potential then flows through a resistor 156 to the base of a switching transistor 157, and through the emitter of the transistor to ground. With the extra current flowing through the base of the transistor 157, the internal resistance from the collector to the emitter of the transister is reduced which allows more current to flow from the nine volt supply line through the transistor 145, a resistor 158 and the transistor 157 to ground. The extra current through the base of the transistor 145 allows the resistance between the collector and emitter of the transistor to be greatly reduced which permits the current from the nine volt supply to flow into the emitter of the transistor 157 and through the collector thereof to the input of the voltage regulator 138.
With the input voltage at seven volts or higher and the ground pin of the voltage regulator 138 connected to ground, the voltage regulator will provide a steady five volt supply relative to the ground line. The five volt supply is connected to the pins 5, 6, 26 and 40 of the microprocessor 13~147~;
129, pin 20 of the buffer 132, pin 20 of the latch 134, pins 1, 27 and 28 of the memory 135, and pin 20 of the display driver 137 for supplying power to the chips and to the logic control on some of the chips.
When water is removed from the measuring container 114, i.e. when the tubes 116 and 117 are tilted to empty them, current flow from the nine volt probe 120 to the start probe 122 is cut, and the small charge on the capacitor 152 drains to ground through the resistor 147 in milliseconds or less. With the resistor 147 holding the pin 7 of the buffer 143 low, the output pin 6 of the buffer 143 is also low.
With the diode 149 blocking reverse flow from the charged capacitor 150, the charge and voltage will slowly drain through the resistor 153 to ground with some flow through the 15 resistor 154 and the buffer 143 to ground. The charge on the capacitor 150 remains high enough to keep the pin 5 of the buffer 143 in the "high" input state and therefore maintains power for approximately forty to fifty seconds. In other words, the display still provides a reading even after the container 114 has been emptied.
When water introduced into the container 114 passes the start probe 122 and reaches the low probe 123, current flows through the nine volt probe 120 and the water to the low probe 123. The current then flows from the low probe 123 25 and through resistors 160 and 161 to ground. A capacitor 163 connected from pin 14 of the buffer 143 to ground is intended to reduce the input noise. With current flowing through the resistors 160 and 161, the potential at the pin 14 of the buffer 143 is sufficiently high to drive the output pin 15 on the buffer to a high potential. With a high potential at pin 115 of the buffer 143, current will flow through a resistor 164 to pin 35 of the microprocessor 129, and will change the input pin 35 from a low potential to a high potential. A
pull down resistor 164(a) reduces the high potential level at the pin 35 to an acceptable level and helps produce the low level input.
When the water level rises to the middle or medium probe 124, current flows from the nine volt probe 120 through the water to the medium probe 124, and through resistors 166 and 167 to ground. A capacitor 168 connected from pin 11 of the buffer 143 to ground is intended to reduce the input noise. With current flowing through the resistors 166 and 167, the potential at pin 11 of the buffer 143 is sufficiently high to drive the output pin 12 of the buffer 143 to a high potential. With the high potential at the pin 12, the current flows through a resistor 170 to pin 36 of the microprocessor 129, changing the input pin 36 from a low potential to a high potential. A pull down resistor 170(a) reduces the high potential level at the pin 36 to an acceptable level and helps reduce the low level inputs.
13V~47~
When the water level reaches the high probe 125, current flows through the nine volt probe 20 and the water to the high probe 125. The current then flows from the high probe 125 through resistors 171 and 172 to ground. A
capacitor 174 connecting pin 9 of the buffer 143 to ground is intended to reduce the input noise. With current flowing through the resistors 171 and 172, the potential at the pin 9 of the buffer 143 is sufficiently high to drive the output pin 10 of the buffer 143 to a high potential. With a high potential at pin 10 of the buffer 143, the current will flow through a resistor 175 to pin 37 of the microprocessor 129, changing the input pin 37 from a low potential to a high potential. A pull down resistor 175(a) reduces the high potential level at the pin 37 to an acceptable level and reduces low level input.
The switch 130 is a binary coded decimal (BCD) switch connected to the octal tri-state buffer 132, with pull down resistors 177 on outputs 1, 2, 4 and 8. Pins labelled "c" are connected to the five volt supply. When the switch 130 is rotated from the 0 to the 9 position, the output from pins 1, 2, 4 and 8 will change states from high to low and low to high to give an e~uivalent output from the switch.
The output pins 1, 2, 4 and 8 are connected to pins 11, 13, 15 and 17, respectively of the buffer 132. The same switch setup is used for the selector switch 131, except that the pull down resistors 178 and the output pins 1, 2, 4 and 8 are connected to pins 2, 4, 6 and 8, respectively of the buffer 132. The switches 130 and 131 are selector switches for speed and spacing inputs to the buffer 132. The speed in question is the speed of travel of the sprayer, and the spacing is the spacing between the sprayer nozzles.
When the speed spacing values are to be read by the microprocessor 129, a high level input is sent from the buffer 132 to the pin 31 of the microprocessor 129 which is in a normally low state, as is the other data select ouput pin 32. When both pins 31 and 32 are in the low state, pins 1 and 19 of the buffer 132 are in the low state, and drive the output pins 3, 5, 7, 9, 18, 16, 14 and 12 into a high impedance. When the pin 31 of the microprocessor 129 goes to 15 a high state, it drives the pin 19 of the buffer 132 to a high state, permitting the data at pins 11, 13, 15 and 17 to appear on pins 3, 5, 7 and 9 of the buffer 132. When the pin 32 of the microprocessor 129 goes high, it drives pin 1 of the buffer 132 high, permitting data on the pins 2, 4, 6 and 20 8 to appear on pins 18, 16, 14 and 12, respectively of the buffer 132.
When the current from the five volt supply line runs through a resistor 180 and a zener diode 181, the voltage at battery drops because of discharge, the supply voltage to the buffer 143 also drops while the voltage at the pin 3 of the .
' . , .
130~76 buffer 143 remains relatively constant. With a drop in supply voltage, the high/low threshold also drops and passes the voltage at pin 3 of buffer 143. Thus, the output pin 2 of the buffer 143 goes to a high state which in turn drives pin 1 of the microprocessor 129 into a high state through resistor 182. A resistor 184 connected to ground helps reduce the voltages at pin 1 to acceptable levels.
Additional switches 186 are connected to input pins 33, 34, 38 and 39 of the microprocessor 129 to pull the input pins from their naturally high states to low states. The switches 186 are opened or closed to make four different selections, namely high or low speed range, high or low spacing range, large or small tube size, and English or metric units.
The memory 135 is a read only memory (ROM) chip containing a program for the microprocessor 129. The data lines from the microprocessor 129 (pins 12 to 19) are connected to pins 11 to 13 and 15 to 19, respectively of the memory 135. The pins 12 to 19 are also connected to the pins 3, 4, 7, 8, 13, 14, 17 and 18, respectively of the latch 134. The latch 134 is a tri-state octal latch. The output lines from the latch 134 which are address lines appear on pins 2, 5, 6, 9, 12, 15, 16 and 19 and are connected to pins 10, 9, 8, 7, 6, 5, 4 and 3, respectively of the memory 135.
Four port line pins 21 to 24 of the microprocessor 129 are -- 11 -- \
13~76 connected to the top address pins 25, 24, 21 and 23, respectively of the memory 135. The "ALE" line on pin 12 of the microprocessor 129 is connected to the enable line of the latch pin 11 of the latch 134. The "PSEN" pin 9 of the microprocessor 129 is connected to the "CS" pin 20 of the memory 135. With this arrangement, the microprocessor 129 can read the program from the memory 135.
By using the following connections, the microprocessor clock can function and run the program: a capacitor 186 is connected to ground and to pin 2 of the microprocessor 129, a capacitor 187 is connected to ground and to pin 3 of the microprocessor 129, and crystal 188 is connected to pins 2 and 3 of the microprocessor. A capacitor 190 is a reset capacitor, which permits the microprocessor to reset internal registers before a program starts to run. For data to be transmitted from the microprocessor 129 to the display driver 137, the pins 21, 22 and 25 of the latter must be connected to pins 10, 12 and 24, respectively of the microprocessor 129. The pin connections illustrated in Fig.
3 between the display driver 137 and the display 110 enable the driver to operate the display. A capacitor 191 connected to ground and to pin 19 of the driver 137, and a resistor 192 connected to the five volt supply and to pin 19 of the driver 137 set up the oscillator which operates the driver 137.
When power is applied to the microprocessor 129 , ~' .
' 13~1~76 using the automatic turn-on circuitry described hereinbefore, the microprocessor immediately proceeds through the program stored in the memory 135. The program automatically monitors the input from the probe buffers 143 and the selector switches 130 and 131, and when given correct sequence of events, mathematically determines the flow rate by using variables determined by the user, including speed and spacing, a unit of time determined by the microprocessor and the predetermined volume of the tube.
When the microprocessor 129 detects a change in the low buffer input, a timer/counter within the microprocessor is started. The timer continues counting as the container 114 fills with water until a change in the output of the medium probe 124 is detected. When the change is detected, the value of the counter is stored in the microprocessor 129 and the computer continues to count until a change in the high probe 125 is detected or an overcount occurs. When a change in the high probe 125 is detected, the count stops and the count values are stored in the microprocessor 129. For an overcount with a medium probe count value, and because the medium probe position is one-half the high probe position, the count is stopped and the count value is doubled and stored in the memory. For an overcount with no probe changes on the medium or high probe, the count is stopped and the microprocessor 129 outputs an overcount display to the liquid , , ' 13~i~7~i crystal display 110.
The microprocessor 129 then examines the switch positions and determines the values for the speed, spacing, tube size and units for the display, the microprocessor 129 then determines the exact flow rate or application rate from the variables of speed, spacing, time measured, units required and the volume of the tube between the probes. When the microprocessor 129 has calculated the displayed value, such value is displayed on the liquid crystal display 110 with the units indicator. The indicators are displayed to show the units used. If an out of range display is calculated, the indicators change to show that the display drive unit is out of the predetermined operating range of the nozzle checker (the apparatus of the present invention). The calculated value will remain on the display 110 until the microprocessor 129 detects a low state on the low buffer 143, i.e. on the low probe 122. This is effected by dumping water out of the tubes 116 and 117. The microprocessor 129 will also reset the timer and clear the display 110 to ready the apparatus for testing another nozzle.
Finally, the microprocessor 129 will wait until the automatic shut-off circuit turns the power off in about forty to fifty seconds if there has been no change in the start probe input. The hex buffer 143 and the associated sensing circuit are the only components that are left on. In this ~3~76 "off" mode the batteries 112 should last approximately one to one and one-half years.
Claims (10)
1. An apparatus for measuring the flow rate of an electrically conductive liquid comprising container means for receiving a predetermined quantity of a flowing liquid;
electrical power supply means; computer means connected to said power supply means; first probe means for initiating operation of the apparatus when liquid flowing into said container means closes a circuit between said first probe means, said power supply means and said computer means;
second probe means connected to said computer means, whereby, when the liquid closes a circuit between said first and second probe means, the computer means can determine the flow rate based on the volume of said container means and the time required to close the circuit between said first and second probe means; and display means connected to said computer means for providing a visual indication of the flow rate.
electrical power supply means; computer means connected to said power supply means; first probe means for initiating operation of the apparatus when liquid flowing into said container means closes a circuit between said first probe means, said power supply means and said computer means;
second probe means connected to said computer means, whereby, when the liquid closes a circuit between said first and second probe means, the computer means can determine the flow rate based on the volume of said container means and the time required to close the circuit between said first and second probe means; and display means connected to said computer means for providing a visual indication of the flow rate.
2. An apparatus according to claim 1, wherein said container means includes tube means for receiving the liquid, said tube means carrying said first and second probe means at spaced apart locations therein.
3. An apparatus according to claim 2, wherein said container means includes casing means carrying said tube means.
4. An apparatus according to claim 3, wherein said tube means includes a substantially U-shaped tube containing said first probe means in one arm thereof.
5. An apparatus according to claim 1, wherein said first and second probe means include a first probe for first contact by the liquid; a second probe for contact by the liquid to complete a circuit between said first and second probes, said power supply means and said computer means; a third probe downstream of said second probe in the direction of liquid travel in said container means for contact by the liquid to complete a circuit between said second and third probes to initiate probe monitoring by said computer means;
and a fourth probe downstream of said third probe in the direction of liquid travel for contact with the liquid to complete a circuit between said third and fourth probes, said fourth probe enabling the computer means to determine flow rate.
and a fourth probe downstream of said third probe in the direction of liquid travel for contact with the liquid to complete a circuit between said third and fourth probes, said fourth probe enabling the computer means to determine flow rate.
6. An apparatus according to claim 5, wherein said container means includes a tube and an inlet in the bottom end thereof for receiving the liquid, said first probe extending into the bottom of said tube, said second probe extending into the tube above said first probe, said third probe extending into the tube above said second probe, and said fourth probe extending into the tube above the third probe, whereby liquid rising in the tube contacts said first probe, said second probe, said third probe and finally said fourth probe.
7. An apparatus according to claim 6, including a fifth probe extending into said tube above said fourth probe for terminating flow rate determining operation of the computer means.
8. An apparatus according to claim 1, including first switch means for programming said computer means to monitor said first and second probe means over a variety of ranges of flow rate.
9. An apparatus according to claim 8, including second switch means for programming said computer means to provide display data in a variety of different units.
10. An apparatus according to claim 8 or 9, wherein said computer means includes microprocessor means for monitoring said probe means and for controlling operation of said display means; and memory means attached to said microprocessor means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000542781A CA1301476C (en) | 1987-07-22 | 1987-07-22 | Flow metering device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000542781A CA1301476C (en) | 1987-07-22 | 1987-07-22 | Flow metering device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1301476C true CA1301476C (en) | 1992-05-26 |
Family
ID=4136124
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000542781A Expired - Lifetime CA1301476C (en) | 1987-07-22 | 1987-07-22 | Flow metering device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1301476C (en) |
-
1987
- 1987-07-22 CA CA000542781A patent/CA1301476C/en not_active Expired - Lifetime
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