US3918846A

US3918846A - Vapor generator feedwater pump

Info

Publication number: US3918846A
Application number: US380717A
Authority: US
Inventors: Max K Winkler
Original assignee: Lear Motors Corp
Current assignee: Lear Motors Corp
Priority date: 1973-07-19
Filing date: 1973-07-19
Publication date: 1975-11-11
Anticipated expiration: 1992-11-11

Abstract

The feedpump is capable of efficiently delivering feedwater at high pressure and maintain its positive flow into the boiler of the vapor generator of an automotive power system. Superheated steam is generated, in the order of 1,000*F and 1,000 psi. The mass of the vapor is controlled to drive a mechanical expander, as a turbine, in a Rankline operating cycle. The feedwater is pumped at the order of 1,000 psi, and involves water at inlet temperatures of several hundred degrees Fahrenheit. The pump is of the radial piston type; is quiet, efficient and compact. Further, the actuating fluid, as oil, is maintained completely separate from the working fluid or feedwater that is pumped, both fluids remaining uncontaminated. An important feature is the direct and effective means to variably control the delivery rate of the feedwater to the boiler. The feedpump may be designed for delivery of the working fluid up to 1,500 psi and higher if required. The pump has ample flow rate capability with inherent smoothness. Efficiencies of up to 90% have been attained at full displacement.

Description

Unite States atet 11 1 Winkler 1 1 Nov. 11, 1975 1 1 VAPOR GENERATOR FEEDWATER PUMP [75] Inventor: Max K. Winkler, Reno. Nev.

[73] Assignee: Lear Motors Corporation, Reno.

Nev.

[22] Filed: July 19, 1973 [21] Appl. No.: 380,717

[52] U.S. C1. 417/269; 417/457; 417/461; 417/387; 417/273 [51] Int. Cl.'- F04B 9/08; E04B 35/02 [58] Field of Search 417/386. 387, 457, 461, 417/498; 91/479 [56] References Cited UNITED STATES PATENTS 1.764.712 6/1930 Brackett et a1. 417/439 1.778.962 10/1930 Potter 417/457 1.955.383 4/1934 Hermann 417/387 2.046.491 7/1936 Scott 417/387 2.419.542 4/1947 Dreisen 417/461 2.458.377 1/1949 Hennings 417/387 3.302.752 2/1967 Shiokawa 417/457 3.435.914 4/1969 Atsumi 417/461 3.494.294 2/1970 Hetz 417/387 3.498.229 3/1970 Prelesnik 417/269 FOREIGN PATENTS OR APPLICATIONS 1.246.847 10/1960 France 417/389 Primary Examiner-William L. Freeh Assistant EraminerS. P. LaPointe Attorney. Agent. or FirmJackson & Jones Law Corporation 7] ABSTRACT The feedpump is capable of efficiently delivering feedwater at high pressure and maintain its positive flow into the boiler of the vapor generator of an automotive power system. Superheated steam is generated. in the order of 1.000F and 1.000 psi. The mass of the vapor is controlled to drive a mechanical expander. as a turbine, in a Rankline operating cycle. The feedwater is pumped at the order of 1,000 psi, and involves water at inlet temperatures of several hundred degrees Fahrenheit. The pump is of the radial piston type; is quiet, efficient and compact. Further. the actuating fluid. as oil, is maintained completely separate from the working fluid or feedwater that is pumped. both fluids remaining uncontaminated. An important feature is the direct and effective means to variably control the delivery rate of the feedwater to the boiler. The feedpump may be designed for delivery of the working fluid up to 1.500 psi and higher if required. The pump has ample flow rate capability with inherent smoothness. Efficiencies of up to 90% have been attained at full displacement.

16 Claims, 17 Drawing Figures OUTLET175) INLET1741 US. Patent Nov. 11, 1975 Sheet 1 of5 3,918,846

US. Patent Nov. 11, 1975 Sheet 2 of5 3,918,846

FBG. 2 25 22 I OUTLET(75) I I' "T T J i i l 4 '1 WK LL I \Q 1 A US. Patent Nov. 11, 1975 Sheet 3 015 3,918,846

US. Patent Nov. 11,1975 Sheet4of5 3,918,846

US. Patent Nov. 11, 1975 Sheet 5 of5 3,918,846

FEGJO .Iib 26 FIG. 31

2e \lllii ilil\\\ E FIG.I3

/50%FLOW 22 POSITION 22 POSITION VAPOR GENERATOR FEEDWATER PUMP BACKGROUND AND SUMMARY OF THE INVENTION The high pressure feedpump hereof incorporates pistons that reciprocate within closely fitting cylinders filled with the actuating fluid, as oil..A flexible diaphragm is positioned between each cylinder cavity and the delivered fluid pump chamber. Held in place and sealed around their periphery, the diaphragms completely separate the oil and the feedwater. The alternate suction and displacement of oil by the pistons actuates the diaphragms and thus results in equal displacement in the water chamber. There is no mechanical connection between diaphragm and piston. As incompressible fluids are present on both sides of the diaphragm, pressure across the diaphragm is always equal. The pump may be operated at any pressure within the structural limits of the pump without stress upon the diaphragms or any reduction in diaphragm life.

The feedpump incorporates fixed stroke pistons driven by an eccentric on a drive shaft. The eccentric converts the shaft rotation to reciprocating motion, driving the radial pistons spaced equally around the shaft. On the displacement or pressure stroke, the oil chamber above the piston is pressurized, to actuate the diaphragm and displaces the feed fluid in the pump chamber under pressure through the outlet valve. During the suction, or return stroke, the piston is held to the eccentric by a positive return band. As the piston, oil, and disphragm are drawn back feedwater enters the pump chamber through the inlet valve.

The piston assemblies are located within the pumps temperature compensating oil reservoir, and are completely lubricated. The oil filled chamber above the pistons are connected to the oil reservoir through a slot in the piston wall and a triangular port in the side of the cylinder. The-piston slot has to be closed before oil can be displaced in the chamber above the piston. That portion of the fixed mechanical stroke during which the piston slot is closed is its effective stroke. The effective stroke or displacement is controlled by varying the relation of the surrounding cylinder port with respect to the piston slot. An annular control plate is incorporated in the pump assembly with a local linkage to each cylin der. Displacement of the controlplate is effected externally of the pump, and thereby controls the effective stroke of the pistons. Close variable control of feedwater delivery to the vapor generator is thereby effected in a simple effective manner.

THE DRAWINGS FIG. 1 is a transverse cross-sectional view through the exemplary feedwater pump, taken along the line 11 in FIG. 2, the displacement control ring being shown between radial lines AA.

FIG. 2 is a longitudinal cross-sectional view through the pump, taken along the line 2-2 of FIG. 1.

FIG. 3 is a view of the pump of FIGS. 1 and 2 from the drive end, with cover attached.

FIGS. 4 and 5 are respective elevational and end views of a control cylinder of the pump.

FIG. 6 is a face view of a diaphragm limiter of the pump.

FIGS. 7 and 8 are respective face and end views of the displacement control ring of the pump.

FIG. 9 is an enlarged view of a cylinder engagement portion of the ring of FIG. 7, as seen from line 9-9 thereof.

FIG. 10 is an elevational view ofa piston of the exemplary pump.

FIG. 11 is a cross-sectional view through the piston of FIG. 10, taken along the line 1111 thereof.

FIG. 12 is a diagrammatic illustration of the piston displacement control means, at the mid-range flow rate.

FIG. 13 illustrates the corresponding mid-flow position of the cylinder ports with respect to the piston slots, per FIG. 12.

FIGS. 14 and 15 diagrammatically show the respective control positions for maximum output flow rate.

FIGS. 16 and 17 diagrammatically illustrate the respective control positions for minimum output delivery rate.

DESCRIPTION OF THE INVENTION In Rankine cycle automotive power systems the feedpump must be capable of efficiently pumping the working fluid up to system pressure and maintain a net positive suction head (NPSH) on the pump. To achieve reasonable system cycle efficiency, the feedwater inlet temperature is in the order of several hundred degrees when the working fluid is water. Continuous NPSH prevents cavitation, which even if slight would upset successful operation of the Rankine cycle.

Reference is made to the installation of a feedwater pump of the type hereof in a closed Rankine cycle automotive engine in copending patent application for Vapor Generators With Low Pollutant Emission of William P. Lear, Ser. No. 261,691, filed June 12, 1972 and assigned to the assignee hereof. A small boost pump is placed at the bottom level of the system water make-up tank to assure a proper suction head. This permits foolproof operation with inlet, temperatures of 250F without feedpump cavitation. The steam vapor output pressure thereof is of the order of 1,000 psi, higher pressure being feasible.

Pump 20 is encased in frame 21. An odd number of radial displacement piston assemblies 22 are used. This effects smooth delivery of the working fluid, heated water herein, with seven piston assemblies in the exemplary pump. Each assembly 22 is sealed into frame 21 with a screw cap 23. The assemblies 22 comprise a central piston 25, surrounded by a control cylinder 30 in a close sliding fit. The construction of pistons 25 is illustrated in enlarged FIGS. 10 and 11; that of cylinders 30, in FIGS. 4, 5. Their joint control of working fluid delivery rate is described hereinafter in connection with FIGS. 12 through 17.

The drive shaft 31 of the pump is rotatably mounted in spaced

roller bearings

32, 33. Integral with the interior end of shaft 31 is an eccentric cylindrical hub 35. A needle bearing 36 is about hub 35, which in turn is held within race 37. The interior end of each piston 25 contains a spherical bearing 40 that is arranged in tangential contact with race 37, as shown in FIGS. 1 and 2. A pin 41 projects through the center of each bearing 40.

Circular bands

42, 42 engage the ends of pins 41. Such arrangement holds the bearings 40 in continual sliding contact against race 37. In this manner each piston 25 executes a full fixed stroke per revolution of hub 35. Also, the cycle of each piston 25 is out-of-phase with the adjacent ones by one-seventh of each revolution of drive shaft 31. This makes for continuous and smooth output fluid flow, with the number of piston assemblies being uneven.

Pistons have slots 26 and a hollow interior 27. The cylinders 30 have ports 29 that communicate with the piston slots 26 in a variable control arrangement. The result is close control of the effective output fluid displacement action by each assembly 22. Towards this end an annular control plate is supported for angular displacement in stator member 45. A stud 52 extends from each cylinder 30 and engages with control plate 50 at an individual opening 53 therein as shown in FIGS. 7, 8 and 9. The openings 53 are bevelled at both

sides

54, 54, permitting studs 52 to turn therein. Angular displacement of annular plate 50 turns studs 52, and correspondingly the angular position of the cylinders 30 and their ports 29 with respect to the pistons 25 and their slots 26. The resultant displacement control of output fluid is explained hereinafter.

In the exemplary system, a remote electrical servomotor control unit 55 is used to displace control ring 50. Motor 56 thereof has a gear-down 57 to operate variable displacement control shaft 60. Control shaft 60 is suitably coupled with plate 50 at its coupling extension 58, see FIGS. 7, 8. Extension 58 has a semispherical cavity 61 for the engagement with a sphere. The sphere 62 connects to control shaft 60 with pin 63, as shown in FIGS. 12, 14, 16. Their operation with respect to the resultant cylinder/piston coaction is set forth in connection with FIGS. 12 to 17 hereinafter. Alternatively, variable delivery of feedwater by pump 20 may be controlled by a lever that extends from shaft 60, and in turn actuated remotely. A rack and pinion is a further way: The pinion is on a rod that extends out of the pump; the rack is on a portion of the rim of plate 50.

The actuating fluid (oil) and the working fluid (water) are continually kept apart so as to not contaminate each other. This is very important in closed cycle vapor power systems. The feedwater section is hermetically sealed to prevent air from entering. Each piston assembly 22 forces controlled oil amounts against elastomer diaphragm 65. The pump is arranged with its oil section on one side of diaphragm 65, the feedwater section being all on the other; on the right side, in FIG. 2. A curved limiter plate 66 is positioned on the oil side of each flexible diaphragm 65. A number of apertures 67 are contained in plates 66 for oil to readily pass across, see FIG. 6. Plates 66 limit the displacement of the associate diaphragms 65 upon removel of piston pressure, see the lower one in FIG. 2. A retainer 69 holds the edges of each diaphragm 65 and its limiter 66 sealed in the stator. Ample openings 67 and ports 68 in the stator premit unimpeded oil flow of the oil in the actuating action. An expansion diaphragm 70 is secured at the oil end of pump 20. It is of rubber, as Buna N of 40 Shore hardness. A spud 71 is crimped in a central hold of diaphragm 70. An air bleed screw 72 extends through spud 71.

A protective end cover (not shown) is attached opposite diaphragm 70. A preferred end cover is of aluminum with external fins to dissipate heat from within the pump. End cover 72 at the right end of pump 20 is seen in FIG. 3. The inlet and output feedwater positions of pump 20 are respectively at 74 and 75. A manifold directs feedwater from inlet 74 to all of the pressure chambers at the right of diaphragm 65. An annular cavity 81 in manifold 80 is adjacent each fluid chamber 85. A manifold plate 82 sets against cavities 81, containing local openings 79. A valve plate 83 next to plate 82 has a central port 84 towards each outlet valve 91. A ring of apertures 86 in plate 83 communicates each cavity 81 and its associated chamber 85. An inlet valve 87 is held at each set of apertures 86 by reentrant spring 89. Spring 89 is set in a groove in retainer 69. The inlet fluid is thus presented to the pressure chambers 85.

Pistons 25 reach their peak oil pressure in succession, resulting in smooth feedwater flow through outlet 75. As described later on, the angular setting of control plate 50 determines the rate of feedwater being pumped, also termed its mass flow rate. Each piston pressures oil through an adjacent oil port 90, see FIG. 2. The actuating oil flows through limiter plate 66 and against flexible diaphragm 65, extending it to the right. Diaphragm 65 thereupon directly transmits this pressure to the feedwater in adjacent chamber 85. This results in movement of the water through port 84 and on to outlet valve 91. The output of valves 91 are ported to respective regions 88, in the successive actions. The manifold 80 communicates the water under pressure from regions 88 to common high pressure outlet 75. During the return stroke of each piston a suction is created, with diaphragm 65 collapsing onto limiter plate 66. The feedwater is drawn into associated pump chamber 85 from manifold reservoir 81, and is contained therein until the next stroke of the corresponding piston 25.

In accordance with the present invention, the effective stroke of the pistons in their fluid displacement or pumping action per cycle, is controlled by the angular setting of their surrounding cylinders. The cylinders 30 are rotated in unison by control plate 50 into their angular setting about respective pistons 25. As set forth, the physical stroke of each piston 25 remains fixed in a given pump. However, the effective stroke of each piston begins when its slots 26 are closed off by its cylinder 30. A closed chamber thereby forms between hollow piston interior 27 and the region 28 above the piston. As the piston is moved upward oil in region 28 is displaced through port 90, and deflects diaphragm 65. Effective pumping by the piston continues until it reaches its top position in the cycle.

FIGS. 12 through 17 are diagrammatic of the operation for controlling the piston's effective stroke. It is understood that the pumping outflow of a given pump is determined by the effective stroke setting for the pistons herein described, as well as the rate of piston strokes namely the RPM of the pump. FIGS. 12, 13 are the midflow or 50% position (A). Control shaft 60 is engaged with control plate 50 through ball 62 and pin 63. Each control cylinder 30 is engaged with plate 50 by a stud 52. Maximum flow per stroke, position (B), is illustrated in FIGS. 14, 15. Plate 50 is therein displaced to the right in (B), wherein stud 52 and pin 63 are shifted 30 from reference (A). The minimum flow position (C) is depicted in FIGS. l6, 17, being shifted 30 to the left of reference (A). The pistons 25 of assemblies 22 are held in the same position in these figures to facilitate explanation of the control principle.

In setting (A) for the 50% flow rate, FIG. 13 shows a piston slot 26 about half covered by the triangular port 29 of cylinder 30. The diagonal side 95 of each port 29 is shaped to effect the desired effective range for the strokes of a given pump, as will now be understood by those skilled in the art. It is noted that each piston has two piston slots 26, 180 apart; and that each cylinder has two ports 29 that coact with them. Piston moves to the left in FIG. 13, and its slots 26 become sealed by the closely fitting cylinder while ports 29 cover them. The maximum flow setting (B) shows a small portion of slot 26 covered by a corner of port 29. This is soon sealed off as the piston moves radially out, providing the longest of the effective stroke. In contrast, the minimum flow setting (C) requires a longer portion of the pistons motion to overcome the longer exposure of its slots 26 by ports 29.

Settings of control plate 50 between maximum flow (B) and mimimum flow (C) produce corresponding intermediate fluid flow rates per piston stroke. The predetermined shape of the diagonal arm 95 of the ports determines the flow rate for each setting, as aforesaid. While piston slots (26) are exposed to the cylinder ports (29), oil from the piston chamber 27 vents into the crankcase, with no pumping pressure being exerted on diaphragm 65. The oil venting occurs through cutouts 96 arranged adjacent to ports 29 in the stator. Such venting takes place during the positions of assemblies 22a and 22b as shown in FIG. 1. The position of control plate 50 in FIGS. 1 and 2 is at the 50% flow or mid-position per (A) of FIGS. 12 and 13.

What is claimed is:

l. A fluid pump comprising:

a plurality of pistons arranged for sequential operation with uniform mechanical strokes;

a flexible diaphragm in the vicinity of each piston with fluid at the discharge face thereof and actuating oil between its opposite face and the piston;

a cylinder in close fit relation about each piston with a port that coacts with an opening slot in the piston wall;

an annular member displaceably mounted in the pump, said member being flat with equi-spaced peripheral slots, and a pin extending from each cylinder into one of the slots; and

means for angularly positioning said member to correspondingly control the range in the stroke of oil vented through the piston slot and its port to thereupon establish the effective stroke of the piston in displacing oil under pressure against its associated diaphragm.

2. A fluid pump as claimed in claim 1, further including a limiter plate positioned adjacent each said diaphragm at its oil side to safely limit its respective displacement upon the cylical removal of pressure thereon from its associate piston.

3. A fluid pump as claimed in claim 2, in which said diaphragms are of elastomer material and normally curved towards their respective fluid chambers, and

their respective limiter plates are similarly curved.

4. A fluid pump as claimed in claim 2, in which each said limiter plate is annularly mounted together with its associated diaphragm and contains apertures for the flow of actuation oil against its said diaphragm.

5. A fluid pump as claimed in claim 3, in which each said limiter plate is annularly mounted together with its associated diaphragm and contains apertures for the flow of actuation oil against its said diaphragm.

6. A fluid pump as claimed in claim 1 wherein said diaphragm is circular and supported annularly with its fluid discharge and actuation faces maintaining positive separation between the fluid and oil throughout operation of the pump.

7. A fluid pump as claimed in claim 6, further including a limiter plate positioned adjacent each said diaphragm at its oil side to safely limit its respective displacement upon the cylical removal of pressure thereon from its associate piston.

8. The fluid pump as claimed in claim 7, in which said diaphragms are of elastomer material and normally curved towards their respective fluid chambers, and their respective limiter plates are similarly curved.

9. A fluid pump as claimed in claim 1, in which said means is an annular member displaceably mounted in the pump.

10. A fluid pump as claimed in claim 9, in which each cylinder is mechanically coupled to said member in a manner to effect the angular resetting of said cylinders in correspondence with the position of said annular member in the pump.

11. A fluid pump as claimed in claim 1, in which said annular member is flat and with equi-spaced peripheral slots, and a pin extending from each cylinder into one of the slots.

12. A fluid pump as claimed in claim 1, in which said port of each cylinder is predeterminedly shaped to effect the desired fluid discharge rate for a given pump speed at corresponding angular settings of said means.

13. A fluid pump as claimed in claim 10, in which said port of each cylinder is predeterminedly shaped to effect the desired fluid discharge rate for a given pump speed at corresponding angular settings of said member.

14. A fluid pump as claimed in claim 1, in which each piston is hollow and has an open end.

15. A fluid pump as claimed in claim 1, in which the wall opening in each piston is a longitudinal slot.

16. A fluid pump as claimed in claim 1, in which each piston is hollow and has an open end, and the wall opening in each piston is a longitudinal slot, a second longitudinal slot in each piston opposite said first one, and a second port in each cylinder in coaction with the second piston slot.

Claims

1. A fluid pump comprising: a plurality of pistons arranged for sequential operation with uniform mechanical strokes; a flexible diaphragm in the vicinity of each piston with fluid at the discharge face thereof and actuating oil between its opposite face and the piston; a cylinder in close fit relation about each piston with a port that coacts with an opening slot in the piston wall; an annular member displaceably mounted in the pump, said member being flat with equi-spaced peripheral slots, and a pin extending from each cylinder into one of the slots; and means for angularly positioning said member to correspondingly control the range in the stroke of oil vented through the piston slot and its port to thereupon establish the effective stroke of the piston in displacing oil under pressure against its associated diaphragm.

3. A fluid pump as claimed in claim 2, in which said diaphragms are of elastomer material and normally curved towards their respective fluid chambers, and their respective limiter plates are similarly curved.

16. A fluid pump as claimed in claim 1, in which each piston is hollow and has an open end, and the wall opening in each piston is a longitudinal slot, a second longitudinal slot in each piston 180* opposite said first one, and a second port in each cylinder in coaction with the second piston slot.