US3065712A - Condensate pump - Google Patents

Description

Nov. 27, 1962 J. D. BUCHANAN ETAL 3,065,712

CONDENSATE PUMP Filed Feb. 6, 1961 2 Sheets-Sheet 1 IIIIIIIIIIIIIIIIIIII JOHN D. BUCHANAN KENNETH A. DARNE Y v INVENTORS Nov. 27, 1962 J. D. BUCHANAN ETAL 3,065,712

CONDENSATE PUMP Filed Feb. 6, 1961 2 Sheets-Sheet 2 FIG. 5.

EXHAUST q JOHN D. BUCHAxAIY H A. DAR E I NVENTORS United States Patent ()fiice 3,i55,7l2 CONDENSATE PUMP John D. Buchanan, Tinionium, and Kenneth A. Barney,

Raspeburg, Md, assignors to The Bendix Corporation, a corporation of Delaware Filed Feb. 6, 1963., Ser. No. 87,470 6 Claims. ((11. 103-255) The present invention relates to a pump. More particularly, it relates to a pump having electrodes immersible in a conductive liquid to cause heating and attendant increase in the vapor pressure of the liquid and thereby provide a force for pumping the liquid.

The pump of the present invention is especially suited for use with dehumidifiers and air conditioners of the refrigerating type. The majority of dehumidifiers in use are provided with a simple drop pan or bucket for collecting the moisture condensed from the air. This arrangement is expedient since it provides for reduced cost of manufacture and permits flexibility in the choice of locating the machine. It is of considerable inconvenience to the user, however, since it necessitates daily or more frequent emptying of the condensate. Accordingly, it is an object of the present invention to provide a simple, reliable pump capable of elevating condensate through reasonable distances.

Another object of the invention is to provide a pump which operates automatically upon the collection of a given volume of liquid.

A further object of the invention is to provide a pump requiring no rotating parts for its operation, thereby improving its reliability and simplifying its manufacture.

Still another object is to provide a condensate pump in which reliability is further improved by the elimination of floats, switches, linkages, etc. from the controls.

Other objects and advantages will become apparent as an understanding of the invention is gained through study of the following description and the accompanying drawings:

Briefly, the present invention comprises a pressure proof housing provided with inlet and outlet valve means Within the housing are a pair of electrodes which upon immersion commence heating the condensate As the temperature within the housing increases, the inlet valve closes and the internal pressure builds up At a certain pressure level the outlet valve opens and entrapped condensate is exhausted, the internal pressure being sufficient to elevate the liquid.

In the drawings:

FIGS. 1 and 2 are vertical sections of the present invention illustrating, respectively, the appearance of the pump elements while condensate is being received but prior to operation of the pump, and the appearance of pump elements during operation of the pump;

FIG. 3 is a horizontal section of the invention illustrating the internal elements in plan;

PEG. 4 is an elevation of the inlet valve for the pump illustrated in FIG. 1;

FIG. 5 is a vertical section of a pump similar to that of FIG. 1, but improved in several respects;

FIG. 6 is a perspective of the inlet valve for the pump illustrated in FIG. 5; and

FIG. 7 is a pictorial representation of the use of the invention as an accessory to a dehumidifier.

Referring to FIGS. l3, the pump includes a sealed housing 10 which may be conveniently moulded in two pieces comprising a body shell 11 and a cover plate 12. The joint 13 between the body shell 11 and cover plate 12 is rabbeted to provide a snug fit and is sealed by means of screws 14 and an adhesive or a suitable silicone-rubber compound applied uniformly along its length. The hous- 3,065,712 Patented Nov. 27., 1962 ing material may satisfactorily be metal or plastic. If plastic is chosen, the material should be capable of withstanding moderate pressure at boiling water temperature without deterioration or deformation.

An inlet nipple 15 is moulded toward the top of one end of the housing 10. Connected thereto is a flexible tube 16 conveying the liquid to be pumped. A vent hole 17 is positioned adjacent the nipple 15 to permit the air displaced by entering liquid to escape. An outlet nipple 18, positioned beneath the inlet nipple 17, includes a check valve 19 in the form of a spring loaded ball. A flexible exhaust hose 21 is connected downstream of the check valve 19 to dispose the pumped liquid in a drain or elsewhere.

A temperature responsive inlet valve 22 is positioned within the housing It) adjacent the apertures of inlet nipple l5 and air vent 17. Valve 22 comprises a bimetallic strip 23, best seen in FIG. 3, secured to the housing end wall by means of screws 24 driven into a projecting boss 25. A valve disk 26, provided with inner and outer O- ring seals 27 and 28, is flexibly secured to the free end of strip 23. Strip 23 is so arranged that increasing temperature bows the strip towards the housing end wall and moves the valve disk into abutment therewith, thus sealing the housing against loss of pressure through either the inlet or the vent apertures. FIGS. 1 and 2 illustrate alternative means of securing valve disk 26 to strip 23.

FIG. 4 is the construction employed for the inlet valve of FIGS. 1 to 3, wherein the free end of strip 23 is pierced, as at 29, to receive a stem 31 on valve disk 26. The stem 31 is then upset or peened to join the disk to the strip. A pair of spaced semi-annular apertures 32 surround aperture 29, leaving the filaments 33 as flexible supports for the disk 26. In the preferred construction of FIG. 6, the free end of strip 23 is slotted and tabs 34 are bent back from the slot. Valve stem 31 is then pivotally secured between the tabs 34 by means of a pin 35.

Again referring to FIGS. 1 and 2, a pair of horizontally extending electrodes 36 and 37 are supported within the housing it by means of conductive straps 33 and 39 moulded into plate 112. A power cord, only the end of which appears at 41, connects straps 33 and 39 and electrodes 36 and 37 to an electrical power source. The upper electrode 36 is planiform and fits within, but does not contact, the cup-shaped lower electrode 37.

The lower electrode 37 is suspended above the bottom of the housing in a suflicient distance to provide a sump of substantial volume. The entering condensate must first fill the sump volume of the housing prior to spilling over the upper lip 42 of electrode 37. When the condensate spills into the cup of electrode 37, a high resistance electrical path is established and heating action commences. As the temperature within the housing rises, valve 22 closes and the internal pressure also begins to increase. Finally, the boiling of the liquid Within the cup of electrode 37 increases the pressure sufficiently to force open the check valve 19 and pump the liquid out, elevating it through whatever head may be present. Steam continues to exhaust through the check valve until finally the liquid in the cup of electrode 37 has boiled away. There will then be no conductive path between electrodes 36 and 37 and heating ceases. As the pump cools, its internal pressure drops and check valve 19 closes. Further cooling produces a partial vacuum within the pump causing inlet valve 22 to open to permit the inrush of the condensate which will have collected in tube 16 during the pump discharge cycle. The generation of the partial vacuum as a result of the provision of check valve 19 is a desirable feature since it forces the opening of inlet valve 22 sooner than that valve would open reaces 712 '3 sponding solely to the internal temperature of the housing. Thus the capacity of the pump is increased.

Several other features contribute to improved operation of the pump. The cup-shaped electrode 3') retains liquid after the check valve 19 has opened and the level of the liquid has dropped below the level of the electrode. Steaming continues until cup 37 has boiled dry, thus insuring that the pump will be completely emptied during an operating cycle. It should also be noted that the level of the lower edge of the bi-metallio strip 23 is above the level of the upper lip of cup 37. This insures that the pump will commence heating before strip 23 becomes immersed. Otherwise, the liquid in the pump would act as a heat sink to strip 23' and the inlet valve would close later than is desirable.

The material from which electrodes 36 and 37 are constructed may be metal or carbon. Nickel and stainless steel have been found satisfactory but carbon is preferred both for its freedom from oxidation and for the fact that the resistance of the electrodes can be deliberately increased by mixing other materials into the carbon. It is desirable that the electrodes present a reasonable amount of resistance as a safety feature. The resistivity of dehumidifier condensate is considerably lower than that of pure distilled water due to the presence of dust and other atmospheric pollutants, say 20,000-40,000 ohms/in. cu. as compared to 150,000 ohms/in. cu. Typical electrodes constructed of a low resistance material draw from 2 to 3 amperes at 110 volts when supplied with dehumidifier condensate having a resistivity of about 20,0tl ohms/in. cu. The addition of a slight amount of salt to the liquid reduces its resistivity to about 2,000 ohms/in. cu. and causes the current to exceed 15 amperes. Greater amounts of salt can reduce the resistivity of the liquid to as low as l820 ohms/in. cu. and virtually short circuit the pump. Since salt or other contaminants may be accidentally or unwittingly introduced into the pump or liquid, a certain amount of electrode resistance may be provided top revent dangerously excessive current demands.

FIG. illustrates an embodiment of the invention improved in several respects over the structure of FIGS. 1-3. The inlet nipple is of an enlarged diameter permitting the use of larger diameter inlet tubing and eliminating the necessity for vent 17 of FIG. 1. The outlet nipple 18 is moulded on the cover plate 12', rather than on the body shell permitting the inlet tubing and outlet hose to be run generally in a straight line. Electrode 37' is riveted directly to cover plate 12' and electrode 36' is riveted to a boss 43 projecting from plate 12, thus eliminating the encapsulation of the conductive straps 38 and 39 and line cord 41 as shown in FIGS. 1 and 2. The connection of the line cord 4-1 to electrodes 36 and 37 is not shown but simply comprises eyelets secured to the opposite ends of the electrode supporting rivets. An insulating cover 4 guards against accidental contact with the exposed electrode rivet heads and terminals of cord 41. A pressure relief plug 45 of the type commonly encountered in pressure cookers is also provided. Plug 45 is designed to blow out at a pressure well below that required to burst the pump housing and thus protects against explosion of the pump, as might occur if the outlet line became clogged.

FIG. 7 illustrates the use of the invention as an accessary to a dehumidifier. Humid air is drawn past the cool evaporator coil 5% of the unit, whereupon droplets of moisture condense and drip down to a collecting trough 51. Trough 51 is moderately funnel-shaped, thus directing the condensate toward an outlet fitting 52. Space is normally provided in the unit housing to contain a drip pan or bucket. In this case, however, the inlet tube 16 of the pump of the present invention has been connected to the fitting 52.. When sufiicient condensate is collected by the pump 19 to immerse its electrodes, heating commences and the pump will operate as hereinbefore described to discharge the condensate through the hose 21 in o a on e nt drain.

Several advantages of the pump are apparent from FIG. 7. Since there is no necessity to provide drop pan or bucket storage space, a pump equipped dehumidifier can be made considerably more compact. Furthermore, the condensate is disposed of through a closed system, rather than remaining in an open pan whence moisture is fed back into the air. 7

It will now be appreciated that the objects of the invention have been realized in a simple, automatically operating, reliable pump. Obviously the pump may be modified or varied in many respects without departing from the teachings of this disclosure. The invention is therefore limited solely by the scope of the appended claims.

The invention claimed is:

l. A pump, comprising a closed pressure resistant housing, an inlet port for admitting conductive liquid to said housing, said inlet port being positioned at an upper level of said housing, an outlet port through which liquid may be exhausted from said housing, said outlet port being at a lower level than said inlet port, a pair of spaced electrodes within said housing and positioned at a level intermediate of the levels of said inlet and outlet ports, means supplying electrical power to said electrodes to cause heating upon immersion of said electrodes by liquid within said housing, and valve means for sealing said inlet port during heating of liquid within said housing.

2. A pump, comprising a closed pressure resistant housing, an inlet port for admitting conductive liquid to said housing, said inlet port being positioned at an upper level of said housing, an outlet port through which liquid may be exhausted from said housing, said outlet port being at a lower level than said inlet port, a pair of spaced electrodes extending horizontally within said housing at a level intermediate of the levels of said inlet and outlet ports, means supplying electrical power to said electrodes to cause heating upon immersion of said electrodes by liquid within said housing, and a temperature responsive valve for sealing said inlet port during heating of liquid within said housing.

3. A pump, comprising a closed pressure resistant housing, an inlet port for admitting conductive liquid to said housing, said inlet port being positioned at an upper level of said housing an outlet port through which liquid may be exhausted from said housing, said outlet port being at a lower level than said inlet port, a first generally cupshaped electrode disposed horizontally within said housing so as to receive and contain a portion of the conductive liquid in said housing, said first electrode being positioned at a level intermediate the levels of said inlet and outlet ports, a second electrode spaced from said first electrode and arranged to contact the liquid within the cup of said first electrode, means supplying electrical power to said electrodes to cause heating so long as sufficient liquid is contained by the cup of said first electrode to maintain contact between said electrodes, and valve means for sealing said intake port during heating of liquid within said housing.

4. A pump as claimed in claim 3 wherein said valve means comprises, in combination, a bimetallic strip fixed at one end and free at the other end and a valve disk pivotally attached to the free end of said strip, said strip being positioned to move said valve disk into facing engagement with said inlet port as temperature increases within said housing.

5. A pump as claimed in claim 4 with additionally, a check valve for preventing entry of liquid into said housing through said outlet port.

6. A condensate pump, comprising a closed pressure resistant housing, an inlet port through which condensate is admitted to said housing by gravity flow, a pair of separated electrodes in said housing including a first generally cupshaped electrode arranged to receive and contain a portion of the condensate in said housing and a second electrode arranged to contact condensate Within the cup of said first electrode, means supplying electrical power to 5 said electrodes, an outlet port through which condensate References Cited in the file of this patent is pumped from said housing, said outlet port and said UNETED STATES PATENTS electrodes being so arranged that condensate entering said housing submerges said outlet port prior to contacting said 1,184,178 B k May 231 1916 electrodes, and valve means for preventing the escape of 5 1343,02? Rltcme Man 1932 steam through said inlet port whereby upon immersion 2,015,672 Hanks 1, 1935 of said electrodes by condensate electrical heating of the condensate commences and pressure resulting from steam- FOREIGN PATENTS ing of the condensate forces evacuation of the condensate 355,001 Germany June 19, 1922 through said outlet port. 10 562,046 Germany Oct. 31, 1930

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