US 3224638 A
Description (OCR text may contain errors)
Dec. 21, 1965 D. HARRELL, JR 3,224,638
ADJUSTABLE LIQUID METERING DEVICE Filed June 9, 1964 20a 20 L i Z flav/a fla/re/fl, J/n 1 I INVENTOR 20 I 30 j ayfl m 50 a United States Patent 3,224,638 ADJUSTABLE LIQUID METERING DEVICE David Harrell, Jr., Austin, Tex., assignor of one-half to Roy T. Walker, Austin, Tex. Filed June 9, 1964, Ser. No. 373,808 5 Claims. (Cl. 222-64) This invention relates to an adjustable liquid metering device and more particularly to an adjustable metering device which delivers a measured volume of liquid to an outlet after receiving the measured quantity from a source of liquid. The invention is particularly useful in measuring the quantity of liquid additives administered to wet cement for strengthening the hardened concrete.
Many structures and buildings are erected with concrete members which are subjected to static and dynamic loads which place various portions of the concrete members in tension or compression. While concrete is a very advantageous construction material, design calculations and sizes must take into account the fact that hardened concrete members have a high elastic limit in compression but are quite weak in tension. To some extent, the lack of similarity in concrete characteristics is accounted for by placing steel cables or the like under tensile stress in the forms which cables are held in equilibrium by the concrete after the concrete sets so that the concrete portion of the member is in compression whereupon stresses caused by external loading and variation from the equilibrium state stay within the elastic range of the concrete member. It may be appreciated that sound engineering practices dictate that the elastic range of concrete members be well known in advance in designing a structure or building.
Chemical additives have been formulated such as Rapidtlo, which is manufactured by the Lambert Corporation, which is added to the wet cement mixture to increase the tensile strength of the hardened structural member. Even when treated cement is used for structural members, it is still essential in the structural and architectural design to rely on the predictability of the tensile strength of a structural member. Those skilled in the art appreciate the fact that accurate measurement of the chemical additives is necessary to obtain the relibility and consistency from one batch of concrete to another and thereby enabling the designer to rely on the greater tensile strength of the chemically treated member. Chemical additives are added to a wet cement mixture by the device of this invention in precisely measured quantities to control the strength of the completed members.
The chemical additives which increase the tensile strength of concrete structural members are handled in liquid form and usually include dissolved chemicals which increase the propensity of the solution to foam and bubble when agitated. Thus, if the chemical additives are mixed .in a large container, a foamy head such as that customarily found on carbonated drinks is likely formed above the liquid and makes measurement from the liquid diflicult due to the problem of ascertaining the line of demarcation between the foam or bubbles and the main body of liquid. Further, some chemical additives are more safely handled by mechanical apparatus and hand measuring is preferably not done.
In many large construction projects, the cement mixer is periodically stoked with the unmixed ingredients around the clock and large dollies or other similar devices are used to transport the wet mixture from the mixing machine to the forms for casting. Additionally, large construction projects may involve the dispatching of a relay of cement-mixer trucks from a central point to the construction site with one truck after another being replenished with supplies and ingredients for the 3,224,638 Patented Dec. 21, 1965 mixing operation which is done while driving from the central stockpile to the construction site. In either case, a large volume of ingredients is used and it may be appreciated that speed in handling the ingredients is essential to completion of the construction project, and even more important, consistency in the entire pour is necessary to build a safe and reliable structure. Therefore, speed and accuracy in the measurement of strengthening additives is necessary to obtain a safe and reliable concrete structure.
Therefore, an object of this invention is to provide a new and useful adjustable liquid measure metering device which automatically withdraws a quantity of liquid from a source and measures the quantity precisely prior to pumping the liquid through an outlet.
An important object of this invention is to provide a new and improved adjustable liquid metering device having an interlock preventing the intake of liquid simultaneous with the delivery of liquid from a calibrated container.
A principal object of this invention is to provide a new and improved liquid metering device which automatically fills a container to a preselected level wherein the means detecting the liquid level senses the level of the liquid without regard to bubbles, foam, or spray above the surface of the liquid.
A further object of this invention is to provide a new and improved adjustable liquid metering device measuring a variable quantity of liquid in a container by positioning liquid detecting means at a preselected level in the container.
Still a further object of this invention is to provide a new and improved liquid metering device for supplying a precise quantity of chemical additives to a cement mix to increase the tensile strength of the hardened mixture.
A primary object of this invention is to provide a new and improved adjustable liquid metering device having upper and lower liquid level detector means which control operation of means for admitting liquid to a container.
Yet another object of this invention is to provide a new and improved liquid metering device which flows current through the liquid to initiate operation of pumping means for exhausting the container.
One object of this invention is to provide a new and improved adjustable liquid metering device which measures a precise quantity of liquid in a container wherein liquid is admitted to and removed from the container at the bottom to avoid agitation, foaming, and bubbling commonly associated with the pouring of a liquid into a container.
The preferred embodiment of this invention will be described hereinafter, together with other features thereof, and additional objects will become evident from such description.
The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown, and wherein:
FIG. 1 is a View of the invention wherein the electrical components are shown in schematic wiring diagram representation and the fluid handling components are represented somewhat schematically; and
FIG. '2 is a front view of the adjustable upper liquid detector means of this invention.
Considering the invention broadly, a source of liquid under pressure, preferably including means such as a pump 19, is connected to a container 15 which is adapted to store a precisely measured quantity of liquid. The container 15 is communicated with means for removing the stored liquid, with such means having the preferred form of an electric pump 16. Motor control means indicated generally at 18 operate the electric pumps and 16 in response to the liquid level in the container as detected by an upper liquid detector means and a lower liquid detector means 21. The detector means 20 and 21 form electrical signals indicating the maximum and minimum liquid level fluctuations allowed for the fluid in the container 15 and such electrical signals are sensed by the control circuitry 18 to operate the pumps 10 and 16.
Considering the invention in more detail, the liquid container 15 is communicated with a reservoir or container of liquid by means of a pipe or conduit 11 which pipe is input to the pump 10 and the pump 10 is connected to the container 15. The output of the pump 10 is communicated with the liquid container 15 by a T 12. The liquid conduit 12 communicates with the bottom 15a of the liquid container 15 and it may be appreciated that the pump 10 urges liquid along the fluid conductor 11 through the inlet 12 into the container 15. Likewise, the pump 16 is connected to the T fitting 12 and timeshares the fitting 12 so that when the fitting 12 is not functioning as an inlet means for the container 15, it is available as an outlet means for the container through the pump 16. The pump 16 urges the measured quantity of liquid through a liquid conductor 17, and a check valve 18 is placed in the conductor 17 to prevent siphoning action in case the liquid level in the liquid conductor 17 is above the level of the liquid in the container 15.
The container 15 is preferably of right cylindrical construction of some clear plastic such as methyl methacrylate resin which is chemically inert to liquid additives and additionally provides suflicient transparency to enable an operator to view the contents of the container. A calibrated strip 23 is positioned adjacent the liquid container 15 and is marked with appropiately spaced calibration marks 2311 along its length to indicate the liquid setting measured by the container 15. The upper liquid detector means 20 is suspended and positioned within the container 15 by means of a pulley 24 which is mounted on a shaft 26 suspended between a pair of upright members 30 positioned on opposite sides of the pulley. A calibration pointer is cooperatively engaged with the calibrations 23a on the member 23 and includes a lock nut 25a for securing the pointer 25 on a vertical guide 31 relative to a particular setting on the scale 23. A suspension wire 27 is connected to the pointer 25 and is looped over the pulley 24 and extends downwardly into the liquid container 15 to provide support means for the upper liquid detector means 20. The flexible member 27 is preferably made of a flexible material providing adequate electrical conductivity for communicating a fiow of current with the liquid in the container. The pointer 27 is also connected to a wire 28 placed in series electrical communication wtih the suspension cable 27 as will be explained in greater detail hereinafter.
The upper liquid detector means 20 has the preferred form of a brass weight having a binding post 20a centrally located on the upper face of the cylindrical weight and the flared shoulder 20b positioned on the binding post 20a to prevent the loop 27a of the support strand 27 from slipping off the detector means 20. The cylindrical weight 20 includes a lower face 20d which is adapted to contact the liquid in the container 15. A plastic drop collector 30 is glued or otherwise attached to the detector means 20 and extends below the lower face 20d to thereby provide means for accumulating liquid collecting on the lower portions of the detector means 20 and conducting such liquid down the drop collector 30 to form a droplet on the lower tip 30a. The collection of any liquid on the collector 30 prevents any inaccuracies arising from the possibility of a droplet of liquid hanging from the lower face 20d of the detector means 20 which might alter the span of distance between the surface of the liquid in the container 15 and the lower face of the detector means 20 to thereby obtain inaccurate detecting of the liquid level in the container 15. Additionally, the dr p collector 30 4 may be enlarged to form means protecting the detector means 20 from bubbles or foam formed on the surface of the liquid in the container 15 where such means would contact and burst the bubbles as might be appreciated when the means 30 is contacted against the foam or bubbles on the surface of the liquid.
The lower liquid detector means 21 is preferably a prong or other similar projection made of conducting metal which extends through the wall of the container 15 into the interior of the container to be contacted by the liquid therein.
The control means indicated generally at 18 is energized by connecting a plug 32 to a power source and by actuating a switch 33 to apply electrical power to the various circuit elements of the control means 18. A transformer 36 having a primary 36a is communicated with the switch 33 by a conductor 35 and the secondary 36b is connected to a rectifying circuit. A diode 38 is connected to charge a capacitor 39 and another diode 40 is connected to the opposite plate of the capacitor 39. The voltage at a terminal 41 connected between the diode 38 and the capacitor 39 is altered from ground potential and current flow from the terminal 41 through a series dropping resistor 42 is communicated by means of a wiper arm 42a of the resistor 42 to the conductor 28 communicating with the apparatus associated with the liquid container 15. The variable resistor 42 is used to supply a preferred voltage to the upper liquid detector means 20 because the conductivity of liquid additives varies.
A relay 45 is connected by a conductor 46 to the capacitor 39 and diode 40 with the conductor 46 communicating with the coil 45a of the relay to operate the relay contacts 45b. A wire 47 is connected to the switch 33 to obtain line voltage for the relay contacts 45b and operation of the relay 45 connects the voltage in the wire 47 through the contacts to a wire 48. The conductor 48 is connected to the coil 50a of a relay 50 having three sets of contacts indicated at 5012, 50c, and 50d. The low voltage sides of the relay coils 45a and 50a are grounded.
The relay contacts 50b are communicated with a wire 51 connected to the wiper arm 42a of the variable resistor 42, and when the contacts 50b are made, the voltage on the wiper arm 42a of the resistor 42 is supplied by the conductor 51 through the contacts to a conductor 52 which is electrically connected to the lower liquid detector means 21. A conductor 54 is connected to obtain line current from the operate switch 33 and communicates with one of the contacts 50c carrying the current by a conductor 55 to the winding 56a of a relay 56. When the contacts 500 are operated, current is switched to the conductor 55 which conductor is connected to operate the relay 56 and the pumps 10 and 16. The relay contacts 50d conduct current in the wire 54 to a wire 58 when the relay 50 is in the unoperated position and the wire 58 communicates with a set of contacts 561; of the relay 56 whereas operation of the relay 50 supplies current to the pump 16 through a conductor 57.
The contacts 56b of the relay 56 are used to switch current flow in the conductor 58 to a conductor 60 which is connected to the pump means 10 to energize same when the relay 56 is in the unenergized position. The conductor 54 is connected to the relay terminals 560 and communicates with a conductor 61 when actuated by the relay 56 wtih the conductor 61 and the conductor 55 connected at a terminal 62. The terminal 62 provides power through a conductor 63 for the relay 56 and it may be appreciated that the operating current is conducted to the terminal 62 from the conductor 54- through two parallel 1 conductive paths extending through each of the relays 50 and 56.
Operation of the liquid metering device of this invention is customarily related to the dispensing of any number of precisely measured liquid additives for batches of cement wherein the liquid additives are stored in a l g con aine T e flu d c nduc r 11 is conn ct d to the source of liquid and the calibration pointer 25 is adjusted to the calibration representing the desired volume of liquid. Such adjustment of the calibration pointer 25 is achieved by loosening the lock nut 25a and physically moving the pointer relative to the scaled member 23 to the selected designation. The lock nut 25a is tightened to clamp the pointer 25 in position and it will be appreciated that the conductive suspension strand 27 is stretched taut by the upper liquid detector means 20 and dangles within the fluid liquid container 15 to an extent dependent upon the location of the calibration pointer 25 relative to the scale 23a. Electrical communication is maintained between the liquid detector 20 and the potentiometer 42 by the electrically conductive cable 27. It is to be noted that the pulley 24 which rotates about the axle 26 provides a 180 degree direction reversal for the liquid detector 20 so that the scale markings 23a are inverted with the minimum measurement which approximates zero quantity positioned at the top of the scale 23a whereas the maximum value of capacity of the liquid container 15 is positioned at the lower end of the member 23 illustrated in FIG. 1. Further, it should be noted that the calibration of the member 23a for zero quantity depends upon the detection of the minimum level by the lower liquid detector means 21 so that a small portion of liquid is left in the container 15 below the level of the liqiud detector 21 and such portion and liquid should be taken into consideration in calibrating the vertically extending member 23. As a practical matter, it is beneficial to maintain some liquid in the container 15 so that the influx of chemically laden liquid through the conduit 11 into the container 15 does not tend to produce a large quantity of foam or bubbles on the surface.
The small portion of liquid in the bottom of the container 15 which remains after operation of the lower liquid detector 21 aids in collecting the foam and bubbles on the surface of the liquid within the container so that the pump means 16 does not pump foam or aerated liquids.
With the upper and lower liquid detectors 20 and 21, positioned, the switch 33 is operated to apply electrical power to the motor control means 18 of this invention. The application of electrical power through the conductor 35 induces a voltage in the secondary 361) which is rectified by the diodes 38 and 40 whereupon a charge is accumulated on the plates of the capacitor 39 altering the voltage of the terminal 41. The voltage of the terminal 41 is connected through the variable resistor 42 and this voltage is conducted to the upper detector means 20 which is left hanging in open space within the liquid container 15 until the liquid is raised to the level of the detector means 20. Because of this, operation of the relay 45 is withheld until the detector means 20 senses the level of liquid within the container 15.
The means for admitting liquid to the container includes the pump means indicated in FIG. 1 which raises the level of the liquid within the container when the pump 10 is energized. Such energization occurs through the flow of current from the conductor 54 through the normally contacted terminal 50a of the relay 50 and the conductor 58. The conductor 58 communicate-s through the normally closed terminals 56b of the relay 56 and current flows through the wire 60 which is connected to the electrically operated pump 10 to operate the pump as means for admitting liquid to the liquid container 15. The operation of the pump means it continues as long as the relays 50 and 56 remain in the unoperated position illustrated in FIG. 1.
Admission of liquid to the container continues until the liquid level approaches the upper liquid detector means and is contacted against the drop collector extending thereb-elow. It may be appreciated that the drop collector 30, which is made of a nonconducting material, is of no significance to operation of the control means 18 of this invention but does function as means for eliminating inaccurate detection by the detection means 20. Also,
the downwardly projecting member it) removes droplets of liquid forming on the lower face 20d of the detector 20 to obtain accurate operation of the device of this invention. The voltage applied through the variable resistor 42 to the liquid detector 20 is communicated through the liquid additive in the container 15 which is a weak electrolyte and provides sufficient conduction for a small current to flow through the apparatus to ground. A flow of current through the electrolyte to ground alters the voltage across the capacitor 39 which is in the range of about 25 V. DC. and the voltage fluctuation of the rectifying means associated with the secondary 36b of the transformer 36 is reflected by the current in the wire 46 which is connected to ground through the coil 45a of the relay 45 to operate the relay to switch the contacts 45b when the liquid level contacts the upper liquid detector means 2! Operation of the relay 45 applies the voltage on the wire 47 to a wire 38 which is connected to the winding of the relay 50 and the relay 50 is operated to reverse the position of the relay terminals 50b, 50c, and 50d.
Operation of the relay 5t switches the contacts 50d to remove the voltage on the wire 58 which is communicated through the relay 56 to the wire 60 and thereby stops operation of the pump 15 so that the pumping of liquid into the container 15 is stopped with the surface of the liquid contacting the lower face 20d of the liquid detector 20. At this juncture, it should be noted that the measured volume of liquid is precisely known resulting from the positioning of the calibration pointer 25 and the measurement of the quantity is made independently of the presence of foam or suds on the surface of the liquid. In this particular, the admission of liquid at the bottom of the container into the main body of liquid tends to reduce the amount of foam and bubbles formed on the surface of the liquid.
While relating operation of the relay 59 to the operation of the relay 45 which results from the detection of liquid by the means 20, the pump 10 is electrically disconnected from the voltage source and the control means 18 functions in an interlocked manner to switch power to the pump 16. This is achieved when the relay 50 operates whereupon the supply voltage in the conductor 54 is communicated through the contacts 50d from the conduction 58 to the conductor 57 which conductor 57 is connected to the outlet pump 16. The pump 16 operates to remove liquid from the container 15 through the T fitting 12 connected to the bottom of the container 15 and such liquid is discharged through the liquid conductor 17 and the check valve 18. It may be appreciated that the pipe 17 may be a flexible tubing or any other suitable means for delivering the quantity of liquid to large trucks equipped with cement mixers or into a stationary cement mixer. Additionally, operation of the relay 50 closes the terminals 551) which communicate the conductor 51 connected to the variable resistor 42 and through a wire 52 which is connected to the lower liquid detector means 21. As the pump 16 removes liquid from the container 15, the change in liquid level breaks the electrical contact between ground and the upper liquid detector means 20 through the electrolytic liquid within the container. However, the lower liquid detector means 21 provides a parallel path through the electrolytic liquid within the container 15 so that the charge condition of the capacitor 39 reflects the presence of liquid within the container 15 as the liquid level fluctuates between the upper liquid detector 2t) and the lower liquid detector 21. As the liquid level goes below the detector 21, the subsequent steps of operation of the device of this invention completes the metering cycle.
The parallel path includes the conductor 51, the relay terminals 5%, and the conductor 52 which communicates through the detector 21 and the liquid additives to ground. Operation of the relay 56 is related to operation of the relay 50 by means of the conductor 55 which is connected to the conductor 54 by means of the terminal 50c when operated to the closed position whereupon the current flow through the terminal 62 energizes the coil 56a of the relay 56 and closes the contacts 56b and 560. The relay 56 is self-holding in that the operation of the relay connects the supply voltage in the conductor 54 through the terminals 560 and the conductor 61 to the terminal 62 resulting in continued operation of the relay 56 without regard to operation of the relay 50. Additionally, the contacts 56b are operated to interrupt the flow of current through the conductor 60 to the pump and the relay 56 inhibits operation of the pump 10 after the relay 50 returns to the quiescent condition illustrated in FIG. 1.
The liquid level in the container is dropped by the pump 16 which expels liquid from the container at the outlet 17 and when the level drops sufiiciently to interrupt the flow of current from the lower liquid detector means 21 to the liquid, the second of the two parallel paths to ground through the liquid is interrupted and the voltage at the terminal 41 fluctuates to reflect this fact. The voltage fluctuation at the terminal 41 is sensed by the capacitor 39, it being recalled that the voltage across a capacitor does not change instantaneously, and the voltage existing across the coil 45a of the relay 45 which is connected to ground is sufficiently altered to allow the relay contacts to drop out which interrupts the flow of current through the conductor 48. Interruption of the flow of current through the wire 48 returns the relay 50 to the quiescent condition illustrated in FIG. 1 and the opened relay contacts 50d interrupt current flow in the conductor 57 to halt operation of the pump 16. As mentioned above, operation of the contacts 500 has no effect on the relay 56 since that relay is self-holding.
The device is left in a ready condition for a second operation, if desired, which is initiated by simply flipping the switch 33 to the illustrated otf position momentarily and returning the switch to apply electrical power to the circuitry of this invention. The momentary interruption of the current flow through the switch 33 lets the relay 56 drop out from the self-holding status.
It should be noted that the self-holding relay 56 does not permit reoperation of the pump 10 which depends on receiving electrical power through the relay contacts 56b of the relay 56.
The pumps 10 and 16 function as pumps to move the liquid from some larger source or reservoir into the liquid container 15 and to remove the liquid from the container 15 in precisely measured quantities. However, the pumps 10 and 16 also function as valves to the extent that the interruption of power for the electric motors of the pumps stops the pumping action so that each pump operates as a barrier to prevent the flow of liquid through the conduits should pressures in the system tend to cause backflow. Therefore, in some applications of the device of this invention, a solenoid valve might be used in lieu of the pump 10 if the conduit member 11 communicates with a source of liquid additives under pressure where such pressure is adequate to fill the container 15 when the valve is opened. Likewise, the relative elevation of the liquid container 15 above the outlet 17 is subject to adjustment to encourage gravity flow from the container 15 through the outlet 17 when desired. If gravity flow is acceptable to the operator of the apparatus, the pump 16 may be replaced by a solenoid valve which would initiate and terminate the gravity flow of liquid from the container 15 through the conduit 17.
During operation of the device of this invention, the measured quantity of liquid may be varied between operations by simply readjusting the calibration pointer to a different setting. At different settings, the invention functions in the same manner with the only distinction being the quantity of liquid measured by the device.
While the foregoing describes the preferred embodiment of this invention, it will be recognized by those skilled in the art that various modifi a ions may be made in the apparatus. For instance, the shape of the nonconducting means placed about the upper liquid detector 20 may be varied dependent upon the propensity of the liquid to foam with the nonconducting means used to burst the bubbles of the foam on the surface of the liquid. In other applications the bursting of the bubbles on the suds may not be desirable because the electrical conductivity of the thin film of liquid comprising the bubble is so small that current flow through the bubbles to the liquid therebelow is insignificant.
An additional modification might include the utilization of a stepping relay with the switch 33 actuated by the drop out of the relay 50 which would automatically interrupt the current supplied through the switch 33 to open the self-holding relay 56. The stepping relay would additionally provide means for presetting the device of this invention to a desired number of operations by initially setting the stepping relay to the desired number of steps.
The foregoing disclosure and description of the invention is illustrative and explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.
What is claimed is:
1. A liquid metering device, comprising:
(a) a liquid container,
(b) an upper electrical detector,
(c) an electrical conductor support connected to the upper detector,
(d) means for movably mounting the conductor support relative to the liquid container,
(e) a lower electrical detector, and
(f) electric circuit means connected to the upper and lower electric detectors for sensing the liquid level in the liquid container.
2. The structure set forth in claim 1, including:
(a) means for filling the liquid container with liquid,
(b) means for discharging liquid from the container,
(c) said electric circuit means electrically connected to the means for discharging liquid, said electric cir cuit means operating same to meter a measured quantity of liquid from the liquid container.
3. The structure set forth in claim 1 including electrical nonconducting means connected to and extending downwardly from the upper electrical detector to protect same from contact with foam, bubbles, or droplets occurring above the surface of liquid in the container.
4. The structure set forth in claim 2 including interlock means associated with the electric circuit means for operating the means for discharging liquid from the con tainer on contact of the liquid to the upper electrical detector and for withholding operation of the means for introducing liquid while discharging liquid, said electric circuit means also operating the means for introducing liquid to the container while said interlock means withholds operation of the means for discharging liquid when the lower electrical detector senses minimum liquid level in the container.
5. A liquid metering device, comprising:
(a) a liquid container,
(b) a source of liquid,
(c) an upper electrical detector,
(d) an electrical conductor support connected to the upper electrical detector,
(e) means for movably mounting the electrical conductor support within the liquid container to define an upper liquid level therein,
(f) a lower electrical detector,
(g) a pipe connected to and opening into the bottom of the containe References Cited by the Examiner UNITED STATES PATENTS Remke 22268 Tarukawa 22276 Schilling 22264 Brown 22217 Hinds et al 22264 Ludwig et a1. 22264 10 LOUIS 1. DEMBO, Primary Examiner.
HADD S. LANE, Examiner.