US3662553A

US3662553A - Valve actuation system for steam engine

Info

Publication number: US3662553A
Application number: US103269A
Authority: US
Inventors: Robert Hodgkinson
Original assignee: STEAM POWER SYSTEMS Inc
Current assignee: STEAM POWER SYSTEMS Inc
Priority date: 1970-12-31
Filing date: 1970-12-31
Publication date: 1972-05-16
Anticipated expiration: 1989-05-16
Also published as: DE2164549A1; IT945839B; GB1343509A; FR2120960A5; CA950871A

Abstract

A steam engine having steam inlet and exhaust poppet valves which are hydraulically actuated by water under pressure. Enginedriven rotary distributors couple a boiler feedwater pump or other source of high-pressure water to the valves, and the distributors deliver gated water pulses to actuate the valves in timed sequence. The inlet-valve distributor is adjustable to provide a variable-admission adjustable-cutoff inlet system for steam supplied to the engine cylinders.

Description

United States Patent [151 3,662,553 Hodgkinson 1 May 16, 1972 54] VALVE ACTUATION SYSTEM FOR 3,402,737 9/1968 Goldstein ..91/4s| x STEAM ENGINE ZEAEJT 5754M F550 Will? SI/MP ca/voavsig Primary Examiner-Edgar W. Geoghegan Assistant E.xaminerAllen M. Ostrager Attorney-Christie, Parker & Hale ABSTRACT A steam engine having steam inlet and exhaust poppet valves which are hydraulically actuated by water under pressure. En gine-driven rotary distributors couple a boiler feedwater pump or other source of high-pressure water to the valves, and the distributors deliver gated water pulses to actuate the valves in timed sequence. The inlet-valve distributor is adjustable to provide a variable-admission adjustable-cutoff inlet system for steam supplied to the engine cylinders.

16 Claims, 13 Drawing Figures mmmm 16 m2 sum 0F 5 I 634 a I BACKGROUND OF THE INVENTION A fundamental problem in designing vapor engines such as a steam engine is the valve system which admits and exhausts steam in an expander such as a piston-cylinder chamber. The valves should be capable of quiet high-speed operation, and must operate dependably at high temperatures associated with superheated steam. A valve system with a variable actuating cycle is normally needed to provide control over engine speed and power, plus the capability of reversing the engine.

Slide valves are well known in the steam field, but are limited in speed and unsuited for high-temperature operation. Rotary valves have also been used for direct admission of steam to an expander, but these valves present many problems in port design and are not satisfactory with high-pressure, high-temperature steam. Poppet valves provide perhaps the best sealing action of any system, but are normally actuated by a camshaft-pushrod arrangement which presents control problems and is complex and noisy. It is also difficult to seal the stems of conventionally driven poppet valves to keep steam out of an oil bath in the engine crankcase.

The valve system of this invention uses poppet valves which are hydraulically actuated by high-pressure water. The flow of water is controlled by a distributor such as a rotary valve which provides engine speed and power control. Steam-sealing problems are eliminated as the valves are isolated from the crankcase oil, and any steam or water leakage past the valve body is harmless as steam is the working fluid used in the engine. The high-temperature capabilities and good sealing characteristics of poppet valves are thus utilized, while the dis advantages of prior-art actuating systems are avoided. Water under pressure to actuate the valves is conveniently obtained from a feedwater pump used with the engine boiler.

SUMMARY OF THE INVENTION Briefly stated, this invention relates to an improved valveactuating system for a vapor engine such as a steam engine having an expander with a vapor valve adapted for hydraulic or fluid operation. The engine includes a vapor generator or boiler for vaporizing a liquid-phase working fluid to drive the engine.

The valve-actuating system includes first means such as a boiler feedwater pump and connecting lines for supplying liquid-phase working fluid under pressure. A distributor means such as an engine-driven rotary valve is connected between the first means and valve. The distributor is operated synchronously with the engine to deliver the pressurized liquid-phase working fluid to open and close the valve in timed relation to the motion of the expander.

Preferably, the system is arranged to actuate all inlet and exhaust vapor valves of the engine which are desirably poppettype valves. In one form, the system includes a shuttle valve for minimizing fluid drain from water-pulse lines between the distributor means and vapor valves.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic diagram of a steam engine with a valve-drive system according to the invention;

FIG. 2 is a stepped sectional elevation of a two-cylinder reciprocating steam engine;

FIG. 3 is a sectional elevation of an exhaust-valve distributor assembly;

FIG. 4 is a view on line 4-4 ofFIG. 3;

FIG. 5 is a view on line 5-5 ofFIG. 3;

FIG. 6 is a view showing a surface development of a ported sleeve used in the exhaust distributor assembly;

FIG. 7 is a sectional view of an inlet-valve distributor assem bly;

FIG. 8 is a view on line 8-8 of FIG. 7;

FIG. 9 is an elevation of a ported sleeve used in the inlet distributor assembly;

FIG. 10 is a view on line 10-10 of FIG. 9;

FIG. 11 is a sectional elevation of a shuttle-valve assembly used with the inlet and exhaust distributors;

FIG. 12 is a view on line 12-12 ofFIG. I1; and

FIG. 13 is a sectional elevation of a portion of the engine showing an inlet poppet valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT The valve-actuation system of this invention will be described in terms of its use in a compound double-acting steam engine 10 shown schematically in FIG. 1. Engine 10 has a high-pressure cylinder 11 and a low-pressure cylinder 12, but vapor engines with any number of cylinders or other types of expanders can use the invention.

Pistons

13 and 14 are fitted in the respective cylinders, and are coupled to a crankshaft 15 by connecting rods 16. The high-pressure cylinder has a pair of inlet valves 17 on opposite sides of piston 13, and a pair of exhaust valves 18 also positioned on opposite sides of the piston. Similarly, low-pressure cylinder 12 has a pair of inlet valves 19 and a pair of exhaust valves 20 respectively positioned on opposite sides of piston 14.

A boiler 24 is fed by a feedwater pump 25 which draws water from a feedwater sump 26. A super-heated steam line 27 is connected between the boiler and inlet valves 17 of the high-pressure cylinder. Exhaust steam from the high-pressure cylinder is directed back to the boiler by a reheat-steam return line 28 connected to the outlet of exhaust valves 18. Reheated steam from the boiler is delivered to inlet valves 19 of the lowpressure cylinder through a line 29. Exhaust from the lowpressure cylinder is directed through an exhaust line 30 to a condenser 31, and outlet water from the condenser is returned to feedwater sump 26 through a water line 32.

The engine also includes an inlet-valve actuating distributor 36 and an exhaust-valve actuating distributor 37 for operating the inlet and exhaust valves of the several cylinders. The two distributors are operated off of crankshafi 15 as suggested by dashed lines 38. High-pressure water from feedwater pump 25 is fed through a line 39 to the distributors. Timed pulses of high-pressure water are gated into the inlet and exhaust valves through

lines

40 and 41 respectively to open and close the valves hydraulically in timed sequence. A valve-drive water return line 42 delivers water from the outlet of the valve-drive distributors to feedwater sump 26. The valve system of the engine is described in greater detail below.

The expander and valve portions of engine 10 are shown in greater detail in FIG. 2 which is a stepped sectional elevation showing low-pressure cylinder 12 and piston 14 on the left of a center line, and high-pressure cylinder 11 and piston 13 on the right. That is, the left and right portions of FIG. 2 are spaced apart along an axis of rotation of crankshaft 15. The pistons are coupled by a pair of piston rods 44 to a pair of conventional crossheads 45 which are in turn connected to the crankshaft by connecting rods 16. The crossheads reciprocate non-compressively in bores 46 in a crankcase 47 which houses the lower portion of the engine. Piston rods 44 pass through seals 48 mounted in an intermediate head 49 secured to the upper end of the crankcase. Cylinders 11 and 12 are defined by a cylinder block 50 secured to the upper surface of intermediate head 49 and are closed by an upper head 51 fastened to the top of the cylinder block.

Poppet-type inlet and

exhaust valves

19 and 20 for the lowpressure cylinder are shown at the left side of FIG. 2. The valves are generally cylindrical, and seal against valve seats 55 and 71 secured in the upper and intermediate heads. The valves are urged toward a closed position by valve springs 56.

Inlet valve 19 is slidably mounted in a cylindrical bore 57 defined by cylinder block 50 and a hollow cap 58 fastened to the top of the upper head. A steam inlet manifold 59 extends into communication with an annular space 60 formed just above valve seat 55 in the upper head. A second chamber 61 is defined eneath valve seat 55 and extends into communication with low-pressure cylinder 12 above piston 14. When the inlet valve is open, steam thus flows from the inlet manifold through the open valve into chamber 61 and the low-pressure cylinder to drive the piston downwardly.

A step piston 65 of reduced diameter extends from the lower end of inlet valve I9 and makes a slip fit in a bore 66 in cylinder block 50. A chamber 67 at the bottom of bore 66 below the step piston is in fluid communication with line 40 which carries high-pressure water from inlet-valve distributor 36 secured to the side of the cylinder block.

Exhaust valve 20 of the low-pressure cylinder is mounted below the inlet valve just described, and is arranged in generally the same fashion as the inlet valve. The exhaust valve makes a slip fit in a cylindrical bore 70 defined by intermediate head 49 and cylinder block 50, and is urged toward a closed position against a seat 71 by a spring 72. A chamber 73 extends from the lower end of the low-pressure cylinder to the upper surface of valve seat 71, and an annular space 74 beneath the valve seat is in communication with an exhaust manifold 75 secured to the side of the intermediate head.

The exhaust manifold feeds into line 30 (not shown) which directs exhaust steam to the condenser (FIG. 1). A step piston 76 extends from the underside of exhaust valve 20 and is slidably mounted in a bore 77 in the intermediate head. The undersurface of the step piston is in fluid communication with line 41 connected to exhaust-valve distributor 37 mounted on the right side of the engine cylinder block.

Another pair of inlet and exhaust valves (not shown) are mounted on the low-pressure cylinder. That is, a pair of inlet and exhaust valves are positioned on each side of the low-pressure piston. A similar valving and manifolding arrangement is provided for the high-pressure cylinder as suggested at the right side of FIG. 2. All of the inlet valves (for both the highand low-pressure cylinders) are operated by a single inletvalve distributor 36, and all of the exhaust valves are operated by a single exhaust-valve distributor 37, the distributors being mounted on bosses 78 on opposite sides of crankcase 47.

Exhaust-valve distributor 37 is shown in detail in FIGS. 3-6. The exhaust distributor includes a generally cylindrical body 80 having mounting flanges 81 (shown in FIG. 2 but omitted in FIGS. 3-6) for attachment to bosses 78. The interior of body 80 is hollow, and defines a cylindrical bore 82 closed at one end by a cover plate 83 secured to the body. Four axially spaced and axially elongated ports or openings 84ABCD extend through the upper wall of body 80, and tubular shuttlevalve housings 86 extend upwardly from body 80 over each opening. As shown in FIG. 2, lines 41 are connected to the upper end of housings 86 to place the engine exhaust valves in fluid communication with openings 84.

A tubular sleeve 90 makes a rotatable slip fit in bore 82 of the exhaust-distributor body. One end of sleeve 90 has an outwardly extending flange 91 to which is secured a cover plate 92 having a drive shaft 93 extending therefrom. A gear 94 is rigidly secured to shaft 93 and mates with another gear (not shown) driven off the engine crankshaft whereby sleeve 90 is rotated at engine speed. A cover bell 95 is fastened to body 80 over plate 92 and shaft 93.

A plurality of spaced inlet ports IOABCD and outlet drain ports IOIABCD extend through sleeve 90 as best seen in the developed surface of the sleeve shown in FIG. 6. Each port is elongated along the circumference of the sleeve, and is enlarged at one end to present a low-impedance fluid path at the instant of valve opening or valve closing. A pair of shallow webs I02 extend across each of the ports to strengthen the sleeve. The webs are recessed beneath the inner and outer surfaces of sleeve 90 (see FIGS. 4-5) to place the several portions of each port in fluid communication with each other.

Ports

100A and 101A are axially positioned to pass beneath opening 84A which communicates through line 41 to the upper exhaust valve of the high-pressure cylinder. Ports [00B and IOIB are positioned to pass beneath opening 848 which communicates through line 41 to the lower exhaust valve of the high-pressure cylinder. Similarly, ports 100C and I01C are in intermittent fluid communication through opening 84C to the lower exhaust valve of the low-pressure cylinder, and

ports D and 101D are in intermittent fluid communication through opening MD with the upper exhaust valve of the lowpressure cylinder. The ports are axially and circumferentially spaced on the sleeve to provide proper phasing of the exhaust valves.

A cylindrical center manifold I05 makes a slip fit within sleeve 90 and is rigidly secured to cover plate 83 by bolts 106. An inlet chamber 107 is defined by a bore which extends from one end of the center manifold to terminate just short of the end of the manifold which is secured to cover plate 83. A drain chamber 108 is formed by a second blind bore which similarly extends from one end of the center manifold to terminate slightly short of the blind end of inlet chamber 107. The open end of inlet chamber I07 is sealed with a plug 109.

As best seen in FIG. 3, tubular sleeve 90 terminates short of cover plate 83, and center manifold is enlarged in diameter between the end of the sleeve and cover plate 83 to fit against the inner surface of body 80. An annular groove 112 is formed in this enlarged-diameter portion, and is sealed on each side by O-rings 113. A slot 114 is formed between a portion of groove I12 and inlet chamber I07 to place the entire groove in fluid communication with the inlet chamber.

An opening 115 extends through body 80 in alignment with groove I12, and a fitting 116 (FIGS. 4-5) is secured to the body over the opening. Line 39 (see FIG. I) is connected to fitting 116 to deliver high-pressure water from the feedwater pump to inlet chamber 107. An opening I17 (FIG. 3) is similarly formed through housing 80, and a drain fitting I18 (FIGS. 4-5) is secured over this opening for connection to water-retum line 42 (FIG. 1).

Opening 117 is aligned with a second annular groove 120 in the center manifold, and groove 120 is cut to a sufficient depth to be in fluid communication with drain chamber 108. The entire drain chamber plus a space 121 within tubular sleeve 90 between cover plate 92 and the end of the center manifold are thus in fluid communication with water-retum line 42. A third annular groove 122 is spaced between the ends of the center manifold, and is cut to a depth sufficient to extend into the drain chamber.

As sleeve 90 is rotated at engine speed, drain ports IOIABCD cyclically form passages between the return chamber and openings MABCD in the exhaust-distributor body. For example, for the rotational position of sleeve 90 shown in FIG. 3, port 101C has opened a fluid path between opening 84C and third annular groove 122. When port I01A rotates into position below opening 84A, a path is established to the return chamber through space 121. Similarly, port 1013 will rotate into position to form a path between opening 848 and third annular groove 122. Finally, port 1010 will rotate under opening 84D to form a fluid path to the drain chamber through second annular groove 120. Opening of these paths releases water from lines 41 and the associated valves are driven closed by the valve springs.

Referring to FIGS. 3 and 5, four radially extending slots 124ABCD are cut from the surface of center manifold I05 into inlet chamber 107. The slots are axially spaced along the manifold to be in alignment with openings MABCD, respectively. As sleeve 90 rotates at engine speed, inlet ports IO0ABCD sequentially place the inlet chamber in fluid communication with openings 84ABCD whereby high-pressure water pulses are cyclically delivered to actuate the engine exhaust valves.

For example, when sleeve 90 is in the position shown in FIG. 3, opening 840 is connected to the inlet chamber through inlet port 100D. In the relative position shown in FIG. 5, a slight additional clockwise rotation of sleeve 90 will open a path through port 100A between opening 84A and slot 124A in the stationary center manifold.

The exhaust-valve distributor provides constant-dwell timing as it is desirable to hold the exhaust valves open during almost the entire return stroke of the piston regardless of engine speed or output power. The stationary center manifold of the exhaust-valve distributor provides this relationship, and difi'ers from the variable-admission cycle provided by the inlet-valve distributor to be described below.

If reversal of the steam engine is desired, re-phasing of the exhaust-valve action is readily achieved by making the center manifold axially movable within the distributor body. In this arrangement, a second set of openings (not shown) are formed through the wall of the manifold to move into alignment with the tubular-sleeve ports to provide the desired reverse phasing of the exhaust valves.

Inlet-valve distributor 36 is shown in detail in FIGS. 7-10, and is similar in many respects to the exhaust-valve distributor. A variable-admission cycle is desired for the inlet valves, however, to provide a speed and power control for the engine. A somewhat different port arrangement and a movable center manifold are accordingly provided in the inlet-valve system.

Distributor 36 includes a generally cylindrical body 130 having an inner bore 131 closed at one end by a cover plate 132. Four axially spaced and elongated ports or openings 133ABCD extend through the upper surface of the distributor body, and tubular shuttle-valve housings 134 (corresponding to housings 86) extend upwardly from the body over openings 133. Lines 40 FIGS. 1-2) connect housings 134 to the inlet valves of the engine.

A tubular sleeve 137 makes a rotatable fit in bore 131 of the inlet-distributor body, and is secured at one end to a cover plate 138 having a drive shaft 139 extending therefrom. A drive gear 140 is secured to shaft I39 and meshes with a gear (not shown) coupled to the crankshaft whereby the sleeve is driven at engine speed. A cover bell 141 is secured to the end of body 130 opposite plate 132, and extends over drive shaft 139. Orings or other appropriate seals are provided throughout the assembly to prevent fluid leakage.

Four circumferentially extending and axially spaced ports I44ABCID are formed through sleeve 137, and the sleeve is stiffened by recessed webs 14$ extending across the ports. As seen in FIGS. 8-10, ports 144A and B are 180' out of phase with each other, and ports 144C and D are also l80 out of phase. Ports 1448 and C are 90 out of phase, resulting in a 90 spacing in the four ports. This phasing provides the correct timing for the pairs of inlet valves on each of the two engine cylinders.

A center manifold 148 makes a rotatable slip fit within tubular sleeve I37, and has a shaft 149 extending from one end through cover plate 132. The shaft is rigidly connected to a control lever 150 which provides a means of varying the dwell of the valves by rotating manifold 148 to vary the timing of the inlet-valve operation.

A blind bore terminating slightly short of the control-lever end of the center manifold defines an inlet chamber 152 which is closed by a plug 153. A similar bore, terminating slightly short of the end of chamber 152, defines a drain chamber 154 in the center manifold.

Sleeve 137 terminates short of cover plate 132, and the end of the center manifold between the cover plate and sleeve is enlarged in diameter to bear against the inner surface of body 130. An annular groove 155 in the enlarged end of center manifold 148 is cut to a depth sufficient to extend into inlet chamber 152, and places the inlet chamber in fluid communication with an opening 157 through body 130. A fitting 158 (FIG. 8) is secured over opening 157, and is adapted for connection to high-pressure water line 39 (FIG. 1) from the feedwater pump. Water under pressure is thus delivered to the inlet chamber of the center manifold regardless of the rotational position of the manifold within body 130.

A second annular groove 160 is formed in the periphery of the center manifold between sleeve 137 and the enlarged end of the manifold. A slot 161 extends inwardly from a portion of groove 160 to place the groove and drain chamber 154 in fluid communication with an opening 162 in body 130. A fitting 163 (FIG. 8) is secured to the body over opening 162 for connection to water-retum line 42 (FIG. 1).

Four elongated. axially aligned ports or slots 164ABCD extend through the wall of the center manifold into inlet chamber 152. The slots are positioned to match the axial spacing of openings 133ABCD respectively. A similar set of slots 165ABCD are formed through the wall of the center manifold into drain chamber 154, and slots 164 and 165 are spaced 180 apart. As best seen in FIG. 8, ports 144 extend slightly less than 180 around the periphery of sleeve I37, whereby the slots 164 and 165 associated with any particular opening 133 are never opened simultaneously.

Rotation of center manifold 148 by control lever 150 varies the duration of steam admission to each cylinder by varying the operating cycle (the number of degrees of crankshaft rotation during which an inlet valve is held open) of the associated inlet valves. The particular manifold position selected determines the duration of steam admission (which can be set at any point from 0 to almost 180 of crankshaft rotation) and hence the engine speed and power.

The manifold is shown in FIG. 8 in a fully cutoff position where no high-pressure water is delivered to the inlet valves, and thus no steam is admitted to the engine cylinders. Rotation of the manifold away from the cutoff position produces actuation of the inlet valves, with valve-closure timing being related to the rotational position of the manifold.

A shuttle-valve assembly (FIGS. 11-12) is preferably used in each of the lines connecting the inletand outlet-valve actuating distributors to the respective valves. The assemblies are installed in shuttle-

valve housings

86 and 134 on the respective distributors, and are used to minimize the amount of water drained from the valves and

lines

40 and 41 when the valves are closed. This feature improves the efiiciency and operating speed of the valve-actuating system as the volume of water pumped during valve actuation is minimized by the shuttle valve.

Referring to FIGS. 11-12, the interior of the shuttle-valve housing defines a smooth cylindrical bore 171, and a cylindrical guide sleeve 172 is fitted in the bore to abut an inwardly extending annular shoulder 173 at the bottom of bore 171. An upper portion of sleeve 172 is reduced in diameter to define an upwardly extending annular flange 174. The guide sleeve is locked in position by a retainer 175 which is threaded into the upper end of the shuttle-valve housing.

Retainer 175 has a downwardly extending annular flange 178 which makes a slip fit within bore 171 and bears against an annular shoulder 179 of the guide sleeve. A hollow fitting 180 is threaded into the top of retainer 175, and

fluid line

40 or 41 to the inlet or exhaust valve is connected to this fitting.

An outer annular chamber 182 is defined by the space between the inner surface of flange 178 and the outer surface of flange 174, and an inner cylindrical chamber 183 is defined by the inside surface of flange 174. A cup-shaped shuttle valve 184 makes a slip fit in chamber 183, and the bottom of the shuttle valve is inwardly tapered to mate with a seat 185 formed toward the lower end of chamber 183.

A plurality of downwardly extending notches 186 are formed in the upper edge of the shuttle valve, and a plurality of ports 187 extend through flange 174 of the guide sleeve above the seated shuttle valve. The space below the seated shuttle valve is in direct fluid communication with opening 84 or 133 in the body of the exhaust or inlet distributor respectively.

When the distributor rotates into a position to deliver highpressure water through opening 84 or 133, the shuttle valve is driven upwardly in chamber 183. If no water is present in the chamber above the shuttle valve, the valve will more upwardly until it abuts the under-surface of retainer 175 as shown in phantom in FIG. 11. Any additional water needed to actuate the valve flows through ports 187, then upwardly in outer annular chamber 182 through notches 186 into fitting 180.

When the supply of high-pressure water to the engine valve is cut off by the distributor, the column of water between the distributor and engine valve is moved back toward the distn'butor by the closure spring associated with the engine valve. This motion of the water column drives shuttle valve 184 downwardly into a seated position as shown in solid line in FIG. 11. Once the valve is seated, no further water is drained into the distributor, and a column of water is trapped in the line coupling the the distributor and engine valve. When the engine valve is subsequently actuated, the shuttle valve moves upwardly in chamber I83 only a sufficient distance to displace the trapped column of water enough to fully open the engine valve.

A slightly modified version of an engine-valve assembly 190 useful in engine 10 is shown in FIG. 13. Assembly 190 includes a generally cylindrical poppet valve 191 having an upper end making a slip fit in a cylindrical bore I92 in upper head 51. An annular valve seat 193 is rigidly secured in the top of cylinder block 50, and the inner surface of the seat defines a bore 194 in which the lower part of poppet valve 191 makes a reciprocating slip fit. The poppet valve and seat have mating surfaces 195 which seat against each other when the valve is closed.

A step-piston 197 of reduced diameter extends from the bottom of poppet valve 191, and makes a slip fit in a bore 198 in the cylinder head. A passage [99 in the bottom of bore 198 below the step piston extends into communication with line 40 (not shown) which connects the assembly to the inlet-valve distributor. A cap 200 is threaded into the upper head above valve I91, and a valve-closure spring 201 is positioned in the hollow interior of the poppet valve. The spring is compressed by cap 200, and urges the poppet valve into a closed position.

A steam inlet manifold 203 receives steam from the boiler (not shown), and the manifold is secured to the side of the upper head and cylinder block of the engine. An inlet nozzle 204 is formed in the inlet manifold and upper head, and extends into communication with an annular chamber 205 in the upper head above valve seat 193 and mating surfaces 195. Poppet valve 191 is reduced in diameter below mating surfaces l95 to define an annular chamber 206. Another chamber 207 is defined between upper head 51 and the top of cylinder block 50, and chamber 207 extends around the periphery of seat 193 and into communication with the engine cylinder. A plurality of radially extending ports 208 are drilled through the wall of valve seat 193 to open a steam passage between

chambers

206 and 207. Appropriate seals 209 are provided throughout the valve assembly.

Poppet valve 191 is normally held in a closed position as shown in FIG. l3 by spring 20], and by the high-pressure steam in chamber 205 which forces the valve downwardly against seat 193. When the valve is to be opened, a high-pressure pulse of water is gated into passage [99 from the associated valve-actuating distributor. The water acts against the undersurface of the step piston to raise the poppet valve, and mating surfaces 195 are separated to admit steam into chamber 206. The steam then passes through ports 208 into chamber 207 to flow into the associated cylinder (not shown in FIG. 13). The valve is essentially balanced when it is open, but closes immediately when the associated distributor rotates into a position to release the water pressure in passage 199.

Several outlet ports 212 extend through the undersurface of poppet valve 19! around the periphery of step piston 197. Any steam which leaks past the upper seals of the poppet valve passes into the interior of the valve body and then through outlet ports 212 into a passage 213 below seat 193. Steam in this passage is returned to condenser 31.

The reduced-diameter step piston at the bottom of poppet valve 19! is used to minimize the amount of high-pressure water which must be delivered from the distributor to open the valve. The step piston can be eliminated if high-speed valve actuation is not required, and both styles of valves are shown in the sectional view of FIG. 2. Valve assembly 190 can also be used as an exhaust valve, but in this case the porting of the valve system is rearranged so the upper part of the valve is in communication with the engine cylinder. That is, the exhaust valve is arranged so it is urged into a seated position by high-pressure steam in the associated engine cylinder.

A significant feature of the valve-actuating system of this invention is that the hydraulic fluid used to operate the engine valves is the same working fluid which (in a vapor phase) operates the engine. As a result, any leakage which mixes the hydraulic and working fluids is harmless, and the severe sealing problems encountered in conventional systems can be ignored. Any valve-actuating water which leaks through the system into the engine cylinders will vaporize harmlessly to steam and be exhausted back to the boiler system. There is thus no concern over contamination of the engine working fluid with the valve-actuating hydraulic fluid since the two fluids are vapor and liquid phases of the same material (water of any other fluid which is selected to drive the engine). The system is also advantageous in that separate pumps are not required as the same feedwater pump which supplies the engine boiler can also supply high-pressure water to the valveactuation distributors.

The mechanical rotary-valve distributor means described above is a presently preferred embodiment of the invention as it provides reliable high-speed gating of water pulses to actuate the valves. Other approaches to the gating function are believed feasible, and are intended to fall within the scope of the invention. For example, high-speed solenoid-actuated electric valves can be connected between the engine steam valves and the source of high pressure water. An engine-driven electric switch is used to open and close the solenoid valves to actuate the engine valves in timed relation to crankshaft rotation. The switch is adapted to vary the dwell or open cycle of the engine valves for speed and power control, and valve-actuation permit reverse operation.

There has been described a valve-actuation system providing variable-admission control for a vapor engine. The system is capable of high-speed valve actuation, and is free from oilcontamination and other severe sealing problems which characterize known steam engines.

What is claimed is:

1. [n a vapor engine having an expander with a vaporadmitting inlet valve adapted for fluid actuation, and a vapor generator for vaporizing a liquid-phase working fluid to drive the engine, a variable admission valve-actuating system comprising:

first means for supplying the liquid-phase working fluid under pressure; and

distributor means connected to the first means and the inlet valve, and coupled to the expander to operate synchronously therewith to deliver actuating pulses of the pressurized liquid-phase working fluid to the inlet valve to operate the valve in adjustable timed relation to motion of the expander.

2. The improvement defined in claim I in which the expander is a reciprocating piston-cylinder type, and the inlet valve is a poppet valve.

3. The improvement defined in claim 2 in which the distributor means is a rotary valve driven by the engine and connected by a fluid-carrying line to the inlet valve.

4. The improvement defined in claim 3 in which the rotary valve is adjustable to operate the inlet valve for forward and reverse operation of the engine, the liquid-phase working fluid is water, and the first means is a feedwater pump supplying water to the vapor generator and to the rotary valve.

5. The improvement defined in claim 4 and further comprising means in the line connecting the rotary and inlet valves for limiting reverse flow of water from the inlet valve toward the rotary valve when the inlet valve is closed, whereby a quantity of water is trapped in the line during engine operation.

6. In a reciprocating steam engine having a piston-cylinder expander, a water reservoir, and a boiler for heating water to produce steam to drive the expander, a valving system comprising:

inlet and exhaust valves on the expander and adapted for hydraulic operation by a pressurized fluid;

a pump connected to the reservoir to deliver water under pressure; and

distributor means driven by the expander and connected between the pump and valves to admit water under pressure to the valves to actuate the valves in a predetermined adjustable sequence.

7. The improvement of claim 6 in which the inlet and exhaust valves are poppet-type valves mounted in the engine to control steam flow into and out of the expander, each valve having a closure spring urging the valve into a seated, closed position, the valves being movably mounted in bores in the engine, each bore defining a chamber at one end of the associated valve, the chamber being in fluid communication with the distributor means to receive water under pressure which moves the valve against the closure spring into an open position.

8. The improvement of claim 7 in which said one end of at least one of the poppet valves is reduced in diameter to define a step piston against which water under pressure from the distributor means acts to open the valve.

9. The improvement of claim 6 in which the distributor means and valves are connected by separate water lines, at least one of the lines including a shuttle valve for limiting reverse flow of water from the valve toward the distributor means.

10. The improvement of claim 9 in which the shuttle valve is ported to permit free forward water flow from the distributor means to the valve.

11. The improvement of claim 6 in which the pump is a feedwater pump connected to the reservoir to deliver water under pressure to both the distributor means and the boiler.

12. The improvement of claim 6 in which the distributor means includes a rotary valve with a variable operating cycle to gate adjustable-duration water pulses to the inlet valve.

13. The improvement of claim 6 in which the distributor means comprises a first rotary valve to drive the inlet valve, and a second rotary valve to drive the exhaust valve.

14. The improvement of claim 13 in which the engine has at least two inlet and two exhaust valves, and in which each rotary valve comprises a hollow housing secured to the engine and having ports in fluid connection with the associated valves, a sleeve rotatably mounted in the housing and connected to the engine to be rotated thereby in synchronism with engine-piston motion, the sleeve having ports alignable with selected housing ports during a portion of each rotation of the sleeve, and a center manifold making a slip fit within the sleeve and having a drain chamber, and an inlet chamber in fluid communication with the pump, each chamber having ports opening into the sleeve ports during a portion of each sleeve rotation whereby gated water pulses are delivered to and released from the valves.

15. The improvement of claim 14 in which the center manifold of the first rotary valve is movably mounted to be adjustable in rotational position with respect to the housing whereby the duration of steam admission to the expander through the inlet valves is adjustable.

16. The improvement of claim 15 in which the inlet and exhaust valves are poppebtype valves mounted in the engine to control steam flow into and out of the expander, each valve having a closure spring urging the valve into a seated, closed position, the valves being movably mounted in bores in the engine, each bore defining a chamber at one end of the associated valve, the chamber being in fluid communication with the associated rotary valve through a conduit to receive water under pressure which moves the valve against the closure spring; and further comprising a shuttle valve in each conduit for limiting reverse flow of water toward the rotary valve; the pump being connected to deliver water under pressure to the boiler and the rotary valves.

II I t I i g ga UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,662,553 Dated ligy 16, 1972 Inventor (s) Robert Hodgkinson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Colum 5, line 23, "Lines #0 FIGS. 1-2)" should read --Lines 40 (FIGS. l-2)--.

Column 6, line 65, "more" should read --move--.

Column 8, line 11, "of" should read or Column 8, line 28, after and", second occurrence insert to delete "valve actuation".

Signed and sealed this Zhth day of October 1972.

(SEAL) Attest:

EDWAPD M.FLETCHER,JR. ROBERT GOTTSCHALK Attestlng Officer Commissioner of Pa tents

Claims

1. In a vapor engine having an expander with a vapor-admitting inlet valve adapted for fluid actuation, and a vapor generator for vaporizing a liquid-phase working fluid to drive the engine, a variable admission valve-actuating system comprising: first means for supplying the liquid-phase working fluid under pressure; and distributor means connected to the first means and the inlet valve, and coupled to the expander to operate synchronously therewith to deliver actuating pulses of the pressurized liquid-phase working fluid to the inlet valve to operate the valve in adjustable timed relation to motion of the expander.

2. The improvement defined in claim 1 in which the expander is a reciprocating piston-cylinder type, and the inlet valve is a poppet valve.

6. In a reciprocating steam engine having a piston-cylinder expander, a water reservoir, and a boiler for heating water to produce steam to drive the expander, a valving system comprising: inlet and exhaust valves on the expander and adapted for hydraulic operation by a pressurized fluid; a pump connected to the reservoir to deliver water under pressure; and distributor means driven by the expander and connected between the pump and valves to admit water under pressure to the valves to actuate the valves in a predetermined adjustable sequence.

16. The improvement of claim 15 in which the inlet and exhaust valves are poppet-type valves mounted in the engine to control steam flow into and out of the expander, each valve having a closure spring urging the valve into a seated, closed position, the valves being movably mounted in bores in the engine, each bore defining a chamber at one end of the associated valve, the chamber being in fluid communication with the associated rotary valve through a conduit to receive water under pressure which moves the valve against the closure spring; and further comprising a shuttle valve in each conduit for limiting reverse flow of water toward the rotary valve; the pump being connected to deliver water under pressure to the boiler and the rotary valves.