US2867974A - Heat motor pump - Google Patents

Description

Jan. 13, 1959 s, N N ER 2,867,974

HEAT MOTOR PUMP Filed April 22, 1952 5 Sheets-Sheet 1 n men f r //dra/0 5/6/70? Il e/mflber A f/ arva Jan. 13, 1959 H. s. WENANDER 2,867,974

I 7 HEAT MOTOR PUMP Filed April 22, 1952 5 Sheets-Sheet 2 fie/"10 y H. S. WENAN DER HEAT MOTOR PUMP Jan. 13, 1959 Filed April 22, 1952 3 Sheets-Sheet 3 I n vm Hard/d kfrenn/ry I e/MOa er United States Patent HEAT MOTOR PUMP Harald Svenning Wenander, Stockholm, Sweden, assignor to Aktiebolaget Bonthron & Ewing, Stockholm, Sweden, a corporation of Sweden Application April 22, 1952, Serial No. 283,789

Claims priority, application Sweden November 29, 1951 1 Claim. (Cl. 60-25) This invention relates to an automatic pump which is particularly useful for burners operating with liquid fuel but which may also be used for many other purposes.

For instance, in certain kerosene stoves fuel is fed from a container to the burner nozzle by pressure,'and air is from time to time pumped into the container by means of a hand pump. When the pressure drops, pumping must again take place, and consequently burners of this type cannot be left without attendance for any long time.

In another type of burners, the so-called pot burners, fuel is allowed to flow by itself from a container placed at a higher level than the burner, the supplied amount of fuel being generally controlled by a float valve. However, this has the disadvantage that the fuel continues to flow even when the flame goes out for any reason. Moreover, it might be desirable to have the fuel container placed below the burner.

The main object of the invention is to provide an automatic pump which will supply liquid fuel to burners of the two types above referred to but which is useful also for other purposes, i. e. for general pumping of reasonable amounts of liquid from one vessel to another. The pump according to the invention is characterized by a boiler adapted to beheated and intended to contain a certain amount of a volatile liquid, a condenser connected to the boiler, a chamber connected to the condenser and so dimensioned as to receive the entire amount of liquid initially contained in the boiler, said chamber forming together with the boiler and the condenser a closed system, a diaphragm forming an outer wall in said system and arranged to initiate and return flow of liquid from the condenser to the boiler, when the pressure in the system drops as the whole quantity of liquid in the boiler is distilled over, and a pump room provided at the opposite side of the diaphragm and connected by check valves to two vessels to suck liquid from one of them and deliver it to the other one in dependence on the movement of the diaphragm caused by varying pressures in the closed system.

In order to obtain the desired pumping force, it is necessary to have a rather great variation in pressure in said closed system. This is achieved by reason of the fact that the air is substantially evacuated from the closed system so that the pressure in it will substantially depend on the vapor pressure of the enclosed liquid. Thus, at temperatures below the boiling point of said liquid, the pressure in the system will be considerably lower than atmospheric pressure. Further, by making the condenser of such dimensions that the amount of heat removed from the system is smaller than the amount of heat supplied, no momentary condensation of vapours takes place, whereby a rather great over-pressure can be obtained without difliculty in the boiling. When the entire quantity of liquid has been distilled over from the boiler to the condensate chamber, the pressure in the system soon drops below atmospheric pressure and at a "ice certain under-pressure the condensate is at once returned to the boiler, in which the boiling starts again. Thus by subjecting the diaphragm to the action of these varying pressures a required pumping force is caused to act upon the liquid which is to be pumped.

Construction of the pump according to the invention is hereinafter described with reference to the accompanying drawings, in which:

Figures 1, 2 and 5 show three different embodiments, while Figures 3 and 4 show details in section along the lines III-III and IV-IV in Figure 2 respectively.

The embodiment shown in Figure 1 is connected to a 'device for supplying fuel under pressure to a burner of the pressure type, while the embodiment shown in Figure 2 is connected to a vessel from which fuel is supplied to a pot burner. However, all the embodiments may be used in connection with any type of burner. It is to be noted that the pumps shown in the different figures are drawn on an enlarged scale as compared with the burners, fuel containers, etc.

Referring to Figure 1, 6 is a boiler adapted to contain a certain amount of volatile liquid, preferably a liquid having a high heat of evaporation, as for instance water. The bottom of the boiler consists of a rather thick plate 7 of a metal having a good heat conductibility, for instance copper, while the rest of the boiler is preferably made of a metal having a lower conductibility, such as stainless steel. The plate 7 extends laterally outside the boiler and its outer end is adapted to project somewhat into the flame of the burner which is to be fed by the pump. Preferably, the plate 7 has such a length that the boiler 6 can be placed at a distance from the burner so as to permit of cooking vessels or the like being properly placed over the burner flame. The plate may also be bent so that the boiler can be placed lower than the burner. By using the burner flame to heat the boiler it is ensured that the pumping will cease substantially as soon as the flame goes out.

A tube 8 leads from the top of the boiler to the upper end of a tube 10, slightly inclined to the horizontal plane. The tube 10 is provided with cooling flanges 9 to serve as a cooler for the vapours produced by the boiling. The other end of the cooler 10 is connected to one end of a U-tube 11, the other end of which is connected to the top of the boiler 6 by means of a return flow tube 12. The branch of the U-tube 11 connected to the cooler may be slightly enlarged and is connected by means of a tube 13 to a chamber 14 in a box 16 divided into two chambers by means of a diaphragm 15 of rubber or the like. filled at all times with liquid of the same kind as is introduced into the boiler.

Thus, the pump comprises a closed system including the boiler 6, the condenser 10, the U-tube 11 for collecting condensate and the chamber 14 connected to the U-tube. The diaphragm 15 limiting the chamber 14 serves as the movable pump member wherein the liquid to be pumped is introduced into the chamber 17 at the opposite side of the diaphragm.

The evacuation of the air from the closed system may, for instance, be carried out by means of a vacuum pump which may be connected to an outlet (not shown), which is then sealed.

The other chamber 17 of the box 14, which forms the pump room, is connected by means of a conduit 18 to a valve housing 20 placed in a fuel container 19. Said valve housing has a channel 21 connecting the conduit 18 to the interior of the container 19 and is normally closed by a valve consisting of a ball 22 resting against an annular shoulder in the channel 21. A channel 23 connects the channel 21 between the check valve 22 The chamber 14 and the tube 13 are and the conduit 18 to a conduit 24 leading to the burner 25. The channel 23 is normally closed by a ball 26 resting against an annular shoulder to serve as a check valve. A channel 27 is connected to the channel 23 between the check valve 26 and the conduit 24 and ends in a pressure compensation vessel 28 mounted on the valve housing.

The operation of the apparatus hereinbefore described is as follows:

Let us assume that the chamber 17 in the box 16 is already filled with fuel from the container 19. As mentioned above, at the beginning a vacuum is established in the boiler system, including the chamber 14 which is filled with liquid upon which the vacuum works, the diaphragm being bent inwardly in said chamber, at the same time as the chamber 17 is extended and filled with fuel from the container 19. Heat is now supplied from the burner 25 to the boiler 6 through the plate 7. The vapours formed in the boiler are condensed in the condenser 10 and the condensate is collected in the U-tube 11. As mentioned above, the condenser is so dimensioned that the vapours are not condensed immediately, but a certain over-pressure (for instance of 1 atm. or higher) arises in the closed system. The diaphragm is thereby pressed outwardly, i. e. the volume of the chamber 17 is decreased and fuel is pumped through the conduit 18 into the channel 23, where the valve 26 is lifted to allow fuel to pass to the conduit 24 and the pressure compensation vessel 28. When the last drops of liquid are vaporized in the boiler, the pressure in the system drops to the same extent as the vapours are condensed in the condenser and within a short time an underpressure will arise. Thus, the diaphragm 15 is pressed inwardly in the chamber 14, at the same time as the chamber 17 sucks fuel from the container 19 through the valve 22 and the conduit 18. The amount of liquid contained in the boiler 6 at the beginning is so measured that the branch of the U-tube 11 connected to the boiler is not filled with liquid. As the diaphragm is pressed inwardly, the liquid level is further raised in the U-tube and when the pressure in the system has dropped down to a rather low value the level of the liquid in the U-tube is so high that the whole quantity of liquid in said tube is at once siphoned into the boiler, where the vaporization starts again with the result above mentioned.

When starting the burner 25 is preheated in a known manner by combustion of alcohol in a trough placed below the burner. Thereby, the flame heats also the plate 7 so that the pump begins to operate and after a few pump strokes, a suflicient initial pressure is reached in the vessel 28. The valve 29 controlling the supply of the fuel to the burner can now be opened.

Referring to Figure 2, the pump is arranged to supply fuel to a pot burner which may be of any type. In the embodiment shown, however, it consists of a pot 30 having a perforated cylindrical wall and a fuel supply conduit 31 ending immediately above the bottom. The pot 30 is surrounded by a tubular casing 32 open at the lower end to draw in air and connected at its upper end to a tube 33 for removing the combustion gases. The conduit 31 extends from a vessel 34 in which the liquid level is kept constant to secure an uniform supply of fuel to the pot burner. This is achieved by means of an overflow tube 35 inserted in the vessel 34 and by means of a conduit 36 connected to a storage container 49 for returning any excess of fuel. A needle valve 38 is adapted to be operated manually by means of a screw 39 to adjust the inlet to the conduit 31.

In Figure 2 the boiler 40 is composed of two cylinders, an upper and a lower one, the upper one having a slightly greater diameter and being connected to the lower one by means of a funnel-shaped portion. The purpose of this device is as follows. The heat transmitting bottom plate 41 extending from the boiler 40 projects into the flame of the pot burner hereinbefore described. A tube 42 connected tangentially to the upper cylindrical portion of the boiler 40 extends first in horizontal direction and is then bent vertically downwards to end in a chamber 43 in a box 45 which is divided into two chambers by a diaphragm 44, in the same way as the box 16 in Figure 1. The vertical portion of the tube 42 is provided with cooling flanges 46 to serve as a condenser.

The other chamber 47 of the box 45 is connected by means of a conduit 48 to a valve housing, through which fuel is to be sucked from the container 49 and pumped to the vessel 34 communicating with the burner. The conduit 48 ends in a cylindrical valve chamber 50, the upper part of which has slightly greater diameter than the lower part. The top of the valve chamber is connected by means of a check valve (ball 51) and a conduit 3'7 with the container 34. A cylindrical valve member 52 having nearly the same diameter and the same height as said lower portion of the valve chamber is inserted in the lower portion. Said valve member has at its bottom a conical tip 53 adapted to close against a correspondingly formed shoulder in the mouth of a conduit 54 leading from the fuel container 49. As can be seen from Figures 2 and 4, the peripheral surface of the valve member 52 has four longitudinal grooves 55 extending from the bottom end of the member and ending slightly below the upper end. One of these grooves is continued by a narrower groove 56 (Figure 3) extending up to the top of said member.

The purpose of this valve is as follows:

The valve member 52 will be lifted by the atmospheric pressure in the conduit 54 when the pressure in the valve chamber has reached a sumcient low value as a result of a pressure drop in the boiler system. However, since the pressure in the conduit 54 acts only against a small part of the surface of the valve member (the tip 53) and the valve member is also rather heavy, no lift will occur until the pressure in the boiler system is very low. As soon as the valve member is slightly lifted so that its entire bottom surface is subjected to the pressure from the conduit 54, it will suddenly he forced upwards at the same time as the liquid in the valve chamber 50 is sucked into the chamber 47 below the diaphragm. The groove 56 in the upper portion of the member 52 will hereby serve as a by-pass channel for small amounts of liquid passing the valve tip 53 before the lifting. Thus, the valve member will be lifted to such an extent that the wider grooves in the peripheral surface thereof will communicate directly with the upper extended portion of the chamber 50. If the groove 56 were not provided, slight lifting of the valve member 52 from its seat by the presence of a solid impurity between the tip 53 and the seat would lead to some leakage, and this leakage past the tip 53 would cause the valve member 52 to be lifted before the desired low pressure is reached in the boiler system. However, owing to the presence of groove 56, any liquid leaking past tip 53 is discharged to the chamber 51 and no lift occurs until the pressure in the boiler system has reached the desired low value.

The operation of the pump shown in Figure 2 is fundamentally the same as that of the pump shown in Figure 1. Thus, the air is evacuated from the boiler system so that in the starting position the diaphragm 44 is located close to the upper wall of the box 45. When the liquid is vaporized in the boiler 40 the pressure increases, and the diaphragm is pressed downwards to force fuel from the valve chamber 5% to the container 34- through the valve 51 and the conduit 37. The condensate formed in the condenser 42 first fills the chamber 43 above the diaphragm and then rises upwards in the tube 42 until the Whole amount of liquid in the boiler is distilled over, whereupon the pressure drops in the boiler system. However, the diaphragm 44 will not be raised until the under-pressure in the system is sufficiently low to lift the Valve member 52. When the sutficient under-pressure is finally reached, the diaphragm is raised so that the liquid in the chamber 43 is drawn back into the boiler at the same time as further quantity of fuel is sucked into the chamber 47. As soon as the first drops I of liquid come into contact with the heated bottom in the boiler the vaporization is again started, with the result that the pressure in the system is increased and the return flow from the tube 42 ceases at once. For a complete pump stroke, however, it is necessary that a certain amount of liquid is at once returned to the boiler. This is assured by the arrangement that the tube 42, as mentioned above, ends tangentially in the boiler, whereby the returning liquid will be induced to flow around the wall of the upper extended cylindrical portion of the boiler, and centrifugal force causes it to remain in circular motion in the upper cylindrical portion before it falls downwardly and enters into the lower portion of the boiler.

In the embodiment shown in Figure 5, the boiler 57 and its boiler plate 58 are the same as in Figure 1 and also in this case, vapour and condensate are passed through a circulating system. From the condenser 59 the condensate is led to a chamber 60 in a box 61, which is divided into two chambers by a horizontal diaphragm 62. The other chamber 63 is connected by means of a conduit 64 to a valve housing, including two check valves (balls) 65, 66 for pumping fuel from a con tainer 67 through conduits 68, 69 to a burner 70 in the same way as described in connection with Figure 1. Also in this case a pressure compensation vessel (not shown) is required between the device and the burner.

The chamber 60 is in communication with the boiler 57 through a conduit 71 and past a valve consisting of a rod 73 movably supported in a vertical sleeve 72. The lower end of this rod is conical to close the inlet to the conduit 71. The sleeve 72 is mounted centrally in the chamber 60 by means of horizontal cross bars 74. The displacement of the rod 73 out of its lower, throttling position is limited by a knob 75 provided on the rod and guided in a longitudinal slot of a certain length in the sleeve 72. A magnet 76 is fixed to the upper end of the rod 73 to co-operate with another magnet 77 fixed centrally on the diaphragm 62. If desired, one of these magnets may be replaced by an iron core. The remainder of the box is preferably made of a nonmagnetic material.

The operation of the device is as follows:

Since an under-pressure is prevailing in the boiler system at the beginning, the diaphragm 62 is depressed and the valve 73 is kept in open position by the attraction between the two magnets. As the liquid in the boiler vaporizes and the pressure increases, the diaphragm 62 is raised. Thereby the valve rod 73 is lifted only to such an extent that its knob 75 engages the upper end of the slot in the sleeve 72. When the diaphragm is further raised, the rod 73 drops to close the outlet and thereupon condensate is collected in the chamber 60. When the whole quantity of liquid in the boiler has been distilled over and consequently the pressure in the system drops, the diaphragm is pressed downwards, and in a certain position it lifts the valve rod on account of the attraction between the two magnets. The liquid collected in the chamber 60 now flows back to the boiler through the conduit 71, whereupon the process is repeated. The pumping of 'fuel from the container 67 through the two check valves 65, 66 takes place in the same way as described in connection with the two other embodiments.

Of course, the embodiments described above and shown in the drawings are given only by way of example and the invention is not limited thereto.

As hereinbefore referred to, the pump according to the invention may also be used for other purposes than supplying liquid fuel to burners, such as for instance, for supply of different kinds of liquids or solutions of chemicals in the desired proportions. In such cases the boiler may be provided with electric heating means.

What we claim is:

An automatic heat motor pump for pumping a liquid which comprises, in combination, a boiler containing a predetermined quantity of a volatile liquid, means for transmitting heat to the boiler for vaporizing said liquid, a condenser having one end in' liquid communicating relationship with the boiler, means defining a first chamber for collecting the condensate from said condenser, said chamber being in liquid communicating relationship with the other end of said condenser and being of sufficient volume to hold all of the liquid contained in said boiler, said chamber, said condenser and said boiler forming a closed system, one wall of said chamber being formed by a flexible diaphragm for direct contact with the condensate collected in said chamber, means defining a second chamber adjacent said first chamber with said flexible diaphragm forming a wall of said second charnber, said second chamber containing the liquid to be pumped, and said flexible diaphragm being drawn into said first chamber upon occurrence of the pressure drop therein when all of the liquid in the boiler has been vaporized to initiate the return flow of liquid from said first chamber to said boiler, said second chamber being connected to a tank containing a supply of the liquid to be pumped and to an efiluent line for discharging the liquid contained in said second chamber, and check valves for regulating the flow of liquid to said second chamber from said supply tank and to said discharge line upon movement of said flexible diaphragm in response to pressure changes in the closed system, said boiler consisting of an upper cylindrical portion, a lower cylindrical portion having a smaller diameter than said upper portion, and a central funnel-shaped portion connecting the two cylindrical portions, and a return conduit for the condensate communicating tangentially with the inner surface of the upper cylindrical portion, whereby condensate returning through said conduit is discharged along the inner surface of said upper cylindrical portion in a circumferentially-directed path.

References Cited in the file of this patent UNITED STATES PATENTS 1,129,433 Stratton Feb. 23, 1915 2,212,28 1| Ullstrand Aug. 20, 1940 2,241,620 Shoeld May 13, 1941 2,402,463 Sullivan June 18, 1946

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