US3351238A - Dispenser with low supply indicator - Google Patents

Description

L. A. GILBERTSON Fild April 29, 1966 ATTORNEY Y INVENTOR. LYNN A. GILBERTSON DISPENSER WITH LOW SUPPLY INDICATOR 495.200 m mzon wwm mmnh mmaimh United States Patent Ofifice 3,351,238 Patented Nov. 7, 1967 3,351,238 DISPENSER WITH LOW SUPPLY INDICATOR Lynn A. Gilbertson, Minneapolis, Minn., assignor to Honeywell Inc., Minneapolis, Minn., a corporation of Delaware Filed Apr. 29, 1966, Ser. No. 546,309 Claims. (Cl. 22223) This invention relates to control apparatus and more particularly to in-place treating apparatus for an electrostatic precipitator.

The invention finds application in treating systems wherein a liquid treating material is applied to the electrostatic precipitator during portions of a treating cycle and wherein this treating material is normally stored in a container and is pumped from the container during those portions of the treating cycle when it is used. An example of a treating system wherein the invention finds particular application is disclosed in the copending application Ser. No. 379,942 of Raymond P. Flagg, filed July 2, 1964, now Patent No. 3,257,778. My invention provides means for monitoring the operation of the pump utilized to supply the liquid treating material by measuring the pressure in a liquid conduit or suction line between the inlet of the pump and the container which contains the liquid. By measuring this pressure when the pump is operated, the invention may be utilized to give an indication of the depletion of the liquid supply and/or a clogging of the liquid conduit which prevents the pumping of liquid therethrough. By placing this monitoring apparatus under the overriding control of the control means for the pump, the monitoring apparatus is rendered operable only during those portions of the cleaning cycle when the pump is operated.

It is, of course, known to connect a pressure responsive device in the suction line of a pump and to have this device perform a function in response to the pressure change in the line when the suction in the line is lost, that is when air is drawn through the line rather than the liquid being pumped. This is shown, for example, in US. Patents 2,765,743 and 2,767,277 wherein the pressure responsive device operates a set of switch contacts which in turn de-energize the pump motor when the suction in the line is lost.

Thus, it will be clear that the applicants invention does not lie in the broad concept of measuring the pressure in the suction line of a pump to determine the operating condition of the pump. Rather, this invention lies in the incorporation of a monitoring system utilizing this broad general principle into an in-place washing or treating apparatus for a gas cleaner and is especially useful to give a remote indication of the depletion of a liquid treating material and/or a clogging of the suction tube between the supply tank and the pump. Since a false indication would be given if this indicating means were rendered operative when the pump was not operated, the indicating means is so incorporated into the control for the treating apparatus that it is placed under overriding control by the control means for the pump. By so doing, a relatively simple and reliable monitoring means for the pump is provided.

Various objects and advantages of the invention will become apparent upon reading the following detailed description of a preferred embodiment of the invention wherein reference is made to the drawing. In the drawing:

FIGURE 1 discloses schematically an air conditioning system including an electrostatic precipitator and an inplace washing system therefor, which in-place washing system utilizes my invention for monitoring the operation of a siphon or aspirator pump which is operable to pump liquid detergent from a tank to a washing manifold. FIGURE 2 discloses a modification of a pressure responsive switching apparatus which forms a part of the invention.

By way of example, the invention has been shown incorporated into a system very similar to that disclosed in the previously mentioned Raymond P. Flagg application Ser. No. 379,942. The details of the washing apparatus will be described only briefly since further details of their construction and operation may be obtained from the Flagg application. FIGURE 1 discloses an air conditioning system including an air flow duct 10 having disposed therein an electrostatic precipitator 11, a fan 12 for propelling air through the system, and a heating or cooling apparatus 13. The electrostatic precipitator 11 includes a power supply 11a, an ionizing section 11b and a collecting section and is preferably housed in an appropriate housing 110' having a drain 112 at the bottom thereof. Disposed at the upper portion of the precipitator, above collector section 11c, is a washing or treat ing manifold 14 which may be a fixed manifold with a plurality of nozzles directed toward the ionizer and collector portions of the precipitator or may be a movable manifold such as that disclosed in the previously mentioned Flagg application. If it is a movable manifold it is preferably driven by an electric motor 15, through a mechanical transmission 16. The details of the power supply 11a are not disclosed since these are well known in the art. Preferably it provides means for converting relatively low voltage alternating current power to relatively high voltage direct current power. Heating or cooling device 13 also has an electrical control 13a which is conventional and of no consequence to this invention.

A system of piping generally designated by the numeral 17 including an electrically operated control valve 20 is adapted to connect manifold 14 to an appropriate supply of water under pressure. Connected in parallel with valve 20, by a system of piping 21, is a detergent pump 22 which may take the form of an aspirator or siphon pump controlled by an electrically operated control valve 23. The pump includes a housing 22a in which there is disclosed a nozzle 22b, 21 flared outlet tube 22c and an injector tube 22d. It will be appreciated that pump 22 has been shown schematically for the sake of simplicity since pumps of this type are well known. A liquid conduit serving as a dip tube or suction tube 24 extends from the injector tube 22 downwardly and into the interior of a detergent storage container or tank 25. Preferably the lower end of conduit 24 is just slightly displaced from the bottom of the tank and is normally submerged in the liquid contained therein. This submerged end will be referred to by the numeral 24a. While it is not essential to the operation of the device, there is preferably provided a flow restriction 24b at or near submerged end 24a. It has been found that the use of the restriction 24b will substantially reduce the effect of heat in the container upon the rate at which liquid is drawn therefrom when valve 23 is opened. Also, the inclusion of the flow restriction substantially increases the negative or suction pressure in tube 24 when the pump is operated. A check valve 26 is disposed downstream of the outlet tube 220 to assure that water does not flow backwards into the aspirator pump when valve 20 is open.

The system may be controlled manually but is preferably under the control of a timer 3t) selectively driven by an electric motor 31 and including a plurality of switch contacts operated thereby in a predetermined time sequence. FIGURE 1 discloses the contacts in the relative positions they assume when the timer is in a stand-by condition, ready for operation. These contacts include a plurality of normally open contacts including a pair of contacts 30a connected in controlling relationship with valve 20, a set of contacts 30b connected in controlling relationship with timer motor 31, contacts 30c connected in controlling relationship with valve 23-, contacts 306! connected in controlling relationship with manifold motor 15, and contacts 30e connected in controlling relationship with fan motor 12. The timer also includes a plurality of normally closed contacts including a set of contacts 30 connected in series with the normal temperature responsive control means for controlling the operation of heating or cooling apparatus 13, a set of contacts 30g connected in series with the normal fan control apparatus in controlling relationship with fan motor 12 and a set of contacts 30h, connected in series with the parallel combination of contacts 302 and 30g, and in controlling relationship with power supply 11a of the electrostatic precipitator. A manual start switch 32 is electrically connected in parallel with contacts 30b and may be operated to initiate energization of timer motor 31. Preferably the time sequence is selected so that upon a very brief operation of motor 31 contacts 3% close and provide a holding circuit so that the timer motor then continues to run through a complete cleaning or washing cycle.

The operation of the timer 30 and the washing system is described in some detail in the previously mentioned copending application of Raymond P. Flagg and will be described only briefly herein. Preferably the time sequence is selected so that upon initiation of a washing cycle, contact 30b closes to provide a holding circuit for motor 31 and contacts 30 30g, and 30h open to de-energize the precipitator power supply, the blower fan and the heating or cooling apparatus preparatory to the beginning of a Washing operation upon the electrostatic precipitator. After a brief time delay, contacts 30a and 30b are closed to begin the operation of manifold motor 15 and to cause valve 20 to open to allow water to flow to the manifold and thus to be applied to the precipitator for washing purposes. After a period of time contacts 30a are opened and contacts 300 are closed to energize valve 23. Thus, the path of the water is diverted through aspirator pump 22 and detergent is pumped from container 25 into piping 17 and to the manifold. After a predetermined time contacts 300 are again opened and a soaking period is preferably entered to allow the detergent to loosen the collected material on the precipitator. After the completion of the soaking period contacts 30a are again closed and valve 20 opened to rinse the detergent and the material loosened thereby from the precipitator. It will be appreciated that a number of detergent applications and subsequent rinsings may be used if desired. After the soaking period is completed, contacts 30a and 30d are opened and the system is allowed to remain idle while the liquid drips from the precipitator. After this drip period has passed, contacts 3% are closed to allow blower 12 to operate and to draw air across the precipitator to complete the drying process. Thereafter the contacts are returned to their stand-by position as disclosed in FIGURE 1.

It will be appreciated that the particular cycle selected will depend upon the application of the precipitator and that the above sequence is given by way of example only.

The structure described thus far has made no mention of the applicants improvement. It has been found that this type of precipitator and washing apparatus are commonly located at out-of-the-way places where visual inspection thereof can not be readily made without at least some inconvenience. The starting button 32 may be located at a position remote from the precipitator so that the person initiating the washing cycle is not necessarily aware of exactly what is going on at the precipitator. In some installations a clock is utilized to close switch 32 at preselected intervals, i.e. once every Week. Under these circumstances, the effectiveness of the washing apparatus is customarily not known until such time as it becomes sufficiently ineffective so that the efliciency of the precipitator drops off noticeably. One of the main causes of ineffective washing is the depletion of the detergent supply in container 25 without the knowledge of the person responsible for looking after the equipment. Obviously, various types of float switches or the like could be incorporated into the system to give some type of indication when the level in the container 25 drops to the point where additional detergent should be added. However, apparatus of this type is generally relatively complicated and costly and not readily compatible with the rest of this system.

My invention provides a simple and relatively inexpensive means for monitoring the liquid level in detergent container 25 from a remote point. This is accomplished by utilizing the known fact that a pressure switch can be operated in response to the difference in pressure existing in the suction line to a pump when the pump is operating and fluid is being pumped and the pressure which exists when the suction is lost. This is done by adding a pressure line 40 which is connected to an operating chamber 41a of a pressure switch 41. Chamber 41a includes a movable wall such as a diaphragm 41b which is operably connected to a switch 41c. In the illustrated embodiment, diaphragm 41b, is normally urged, by a spring 41d, to a position wherein switch 41c is closed. The apparatus is constructed so that when pump 22 is operated and end 24a is submerged in detergent, the negative pressure in fluid conduit 24 causes diaphragm 41b to move to a position to open switch 410. However, when the detergent level in container 25 drops to a position so that end 24a of the conduit is no longer submerged, the pressure sensed will be substantially atmospheric and the diaphragm will be disposed in substantially the position in which it is shown in FIGURE 1 and switch 410 will remain closed. When flow restriction 24b is included in the conduit, the negative pressure in the conduit when the pump is operated and end 24a is submerged is substantially greater than when the restriction is omitted. Thus, by including the restriction a less sensitive pressure switch may be utilized than is necessary if the restriction is omitted. Since 410 will also be closed during those times when pump 22 is not operated, it is essential that the pressure switch be rendered effective only during those portions of a washing cycle when the pump is operated or it would give a false indication of a low detergent level. This is accomplished by connecting switch 410 in parallel with valve 23 so that switch contacts 300 are connected in overriding controlling relationship with the pressure switch.

Switch 41c may be connected in direct controlling relationship with a remote indicating apparatus such as a light 42. However, in order to avoid nuisance indications of low detergent level, due to mere momentary fluctuations in pressure, I prefer to provide a time delay means so that a given pressure condition must exist for a predetermined time before a change is indicated by the remote indicating means. Also, it is desirable to have the device constructed so that 'once the indictaing means has been activated it will remain so activated even if it goes unnoticed until the washing cycle is completed. Both of these desirable features have been acomplished by utilization of a conventional latching safety switch which I have shown schematically as being incorporated into the pressure switch 41. A pair of contacts 43a and 43b are connected in controlling, series, relationship with the remote indicating bulb 42. A spring 44 urges these contacts to a closed position but they are normally maintained separated by a bimetallic member 45. Disposed in good heat transfer relationship with bimetallic member 45, and connected in series with switch 410, is an electric heater 46. The apparatus is constructed and arranged so that after a predetermined energization period of heater 46, for example 10 or 15 seconds, bimetallic member45 is deflected sufliciently to releasethe member carrying contact 43a so that the contacts close. They are then maintainer closed by the action of spring 44 and remote indicating light 42 is energized and remains energized until the safety switch is again reset by depressing a reset button 47 located at the pressure switch. Since the pressure switch 41 will normally be located near the precipitator and the detergent tank 25', light 42 can be extinguished only by actually going to the precipitator and determining what has caused the light to come on, that is to discover the detergent tank is empty.

It will be appreciated that a similar indicating apparatus may be incorporated in a system which does not have the timer 30. It can be incorporated equally as well into a system wherein manual switches are operated to sequence the washing apparatus. It is essential, however, that the control apparatus for the detergent pump, whether this pump be of the aspirator type or of some motor driven type, be connected in overriding controlling relationship with the pressure switch so that the pressure switch is operative to bring about an indictaing output, such as the energization of light 42, only when the pump is being operated.

As indicated previously, a similar arrangement may be utilized to detect a clogging of the dip tube 24. FIGURE 2 discloses a modified pressure switch 141 which is similar in all respects to switch 41 except that it has an additional switch 150 incorporated therein. Switch 150 is constructed so that it remains open when the diaphragm is exposed to the atmospheric or substantially atmospheric pressure which exists in the dip tube when end 24a is above the surface of the liquid and at the negative pressure which exists in the dip tube during normal operation of the aspirator pump when end 24a is submerged. However, upon the existence of a greater negative pressure in the dip tube, caused by the clogging of the dip tube, this switch closes. Thus, diaphragm 14117 and switches 1410 and 159 connected thereto, has three effective positions. In the first, which it occupies when subjected to substantially atmospheric pressure, switch 1410 is closed and switch 150 is open. In the second, occupied when the device is subjected to the negative pressure resulting when the pump is operating and drawing liquid through conduit 24 in a normal manner, both switches are open. When conduit 24 becomes clogged, a greater negative pressure exists therein and the diaphragm moves to a third position wherein switch 150 is closed and switch 141c is open.

Switch 150 may be connected directly in parallel with switch 1410 so that if it closes, heater 146 is energized and a continuation of this pressure condition in the dip tube will ultimately result in deflection of bimetal 145 and the closure of the contacts to cause energization of the remote indicating apparatus. It will be obvious that switch 150 may be utilized to operate a separate indicating apparatusif desired. It will also be obvious that switch 150 may be utilized alone so that the indicating apparatus is responsive only to a clogged dip tube and not to a depleted detergent supply.

The operation of the system utilizing my invention has already been described in connection with the description of the structure. It will be sufiicient to say that the sensing apparatus is rendered operative only during those portions of a washing cycle wherein the pump is energized and then a sensed pressure condition must exist for a predetermined time before the pressure switch apparatus is operative to give a remote indication. Once the remote indicator has been operated, it preferably can be rendered inoperative only by going to the precipitator apparatus and resetting the pressure switch.

It is to be understood that a preferred embodiment has been shown and described herein for illustrative purposes. Various modifications may become apparent to those skilled in the art in view of my disclosure herein. Therefore, my invention is to be limited solely by the scope of the appended claims.

I claim:

1. In an in-place treating apparatus for a gas cleaner wherein the treating apparatus includes treating manifold means, a container for holding a supply of treating liquid,

liquid conduit means connecting the container to the manifold means, pump means in said conduit means operable to pump treating liquid from the container to the manifold means, and control means for the treating apparatus operable to sequence the apparatus through a treating cycle having only portions thereof during which the pump means is operated, the improvement comprising: said conduit means including a portion having an opening into said container at a level therein which is normally beneath the surface of the treating liquid therein; pressure responsive means connected to said conduit means and operable by pressure therein between said opening and said pump means; output means operable by said pressure responsive means upon the existence of predetermined pressure conditions sensed thereby; and means controlled by said control means, normally precluding operation of said output means by said pressure responsive means, and rendering said output means operable by said pressure responsive means only during portions of the treating cycle when said pump means is operated.

2. The apparatus of claim 1 wherein the pump means is electrically operable and the control means includes control switch means connected in controlling relationship with the pump means; wherein said output means comprises electrically operable indicator means and said pres sure responsive means includes pressure switch means operably connected in controlling relationship with said indicator means; and wherein said control switch means is operably connected in overriding controlling relationship with said indicator means and renders said indicator means operable by said pressure responsive means only during portions of the treating cycle when the pump means is energized.

3. The apparatus of claim 2 wherein said pressure responsive means includes time delay means rendering said pressure responsive means effective to change the energization of said indicator means only after one of said predetermined pressure conditions has existed for a predetermined period of time.

4. The apparatus of claim 2 wherein said pressure switch means is operable between a first control position which it maintains in response to a predetermined negative pressure which exists in said conduit means between said opening and the pump means when said opening is submerged in liquid and the pump means is operated, and a second control position which it maintains in response to a predetermined greater pressure which exists therein when the liquid level is below said opening in the conduit means and the pump means is operated.

5. The apparatus of claim 4 wherein said pressure responsive means includes a movable wall responsive to the pressure between said normally submerged opening and said pump means, a first normally open switch operably connected to said movable wall and movable thereby to a closed position when said wall senses said predetermined greater pressure, an electric heater, first circuit means adapted to connect said heater to a source of power and connecting said first switch in controlling relationship with said heater, and a second normally open switch and including temperature responsive actuator means for closing said second switch upon a predetermined increase in temperature, said actuator being disposed in heat transfer relationship with said heater and effective to close said second switch only after said heater has been energized for a predetermined time; wherein the apparatus includes second circuit means adapted to connect said indicator means to a source of power and connecting said second switch in controlling relationship therewith; and wherein said first circuit means includes said control switch means connected in overriding controlling relationship with said heater.

6. The apparatus of claim 5 wherein said second normally open switch has associated therewith means for latching it closed when it is closed by said actuator means, and reset means manually operable to override said latch means to move said second normally open switch from closed to open position.

7. The apparatus of claim 1 wherein said opening of the conduit means is disposed at a fixed distance above the bottom of the container and the pressure responsive means includes switch means operated thereby between a first control position in response to the existence of a predetermined negative pressure when the pump is operated and said opening is submerged and a second control position in response to the existence of a predetermined greater pressure in the conduit when the liquid level in the container is below said opening and the pump means is operated.

8. The apparatus of claim 7 wherein said switch means normally is in said first control position, includes latch means which latches said switch means in said second control position when moved thereto, and further includes manual reset means operable to move said switch means from said second to said first control position.

9. The apparatus of claim 7 wherein said switch means includes a third control position to which it is operated when said pressure responsive means senses a predetermined greater negative pressure, resulting from said conduit means becoming clogged, when said pump means is I operated.

10. The apparatus of claim 1 wherein said liquid conduit means includes flow restriction means at or near said normally submerged opening.

References Cited ROBERT B. REEVES, Primary Examiner.

20 HADD S. LANE, Assistant Examiner.

Claims (1)

1. IN AN IN-PLACE TREATING APPARATUS OF A GAS CLEANER WHEREIN THE TREATING APPARATUS INCLUDES TREATING MANIFOLD MEANS, A CONTAINER FOR HOLDING A SUPPLY OF TREATING LIQUID, LIQUID CONDUIT MEANS CONNECTING THE CONTAINER TO THE MANIFOLD MEANS, PUMP MEANS IN SAID CONDUIT MEANS OPERABLE TO PUMP TREATING LIQUID FROM THE CONTAINER TO THE MANIFOLD MEANS, AND CONTROL MEANS FOR THE TREATING APPARATUS OPERABLE TO SEQUENCE THE APPARATUS THROUGH A TREATING CYCLE HAVING ONLY PORTIONS THEREOF DURING WHICH THE PUMP MEANS IS OPERATED, THE INPROVEMENT COMPRISING: SAID CONDUIT MEANS INCLUDING A PORTION HAVING AN OPENING INTO SAID CONTAINER AT A LEVEL THEREIN WHICH IS NORMALLY BENEATH THE SURFACE OF THE TREATING LIQUID THEREIN; PRESSURE RESPONSIVE MEANS CONNECTED TO SAID CONDUIT MEANS AND OPERABLE BY PRESSURE THEREIN BETWEEN SAID OPENING AND SAID PUMP MEANS; OUTPUT MEANS OPERAWBLE BY SAID PRESSURE RESPONSIVE MEANS UPON THE EXISTENCE OF PREDETERMINED PRESSURE CONDITIONS SENSED THEREBY: AND MEANS CONTROLLED BY SAID CONTROL MEANS, NORMALLY PRECLUDING OPERATION OF SAID OUTPUT

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