US2406291A - Steam engine - Google Patents

Description

Aug. 20, 1946. E. s. HALL STEAM'ENGINE Filed Sept. 9, 1943 2- Sheets-Sheet 1 Au 2o,1946. E. SQHALL 2,406,291

STEAM ENGINE Filed Sept. 9, 1945 2 Sheets-Sheet 2 INVENTOR Patented Aug. 20, 1946 UNITED STATES PATENT OFFlCEl STEAM ENGINE Edwin S. Hall, Farmington, Conn.

Application September 9, 1943, Serial No. 501,653 11 Claims. (oi. 121 50 The invention relates to steam engines especially, and to expansible chamber engines in general. A particular object is to provide an improved steam engine of about one-third the bulk and weight of an ordinary steam engine of equivalent piston displacement, an engine capable of running two to five times faster, to deliver six to fifteen times the horsepower from a given amount of room and weight of metal. The engine is of the barrel type, having cylinders parallel to the shaft. In discussing barrel engine mechanisms, confusion has been prevalent, such terms as swashplate and wabbler having been used indiscriminantly or incorrectly. To avoid confusion, these terms are avoided, and herein a plate member inclined to and rotating with the shaft is called a slant; a plate member mounted on bearings on and inclined to the shaft, and having arms operably connected to the reciprocating members, is called a starp-late; and the reciprocating members may be conveniently abbreviated to recipers.

Another object of the invention is toprovide an eflicient steam engine, mechanically balanced to permit high speed, and having large ports and free flowing valves for efiicient handling of the working medium at high speed, with low throt tling losses and low heat losses, an engine capable of operation on an unusually low water rate, an engine in which the steam enters the cylinder at one end and exhausts at the other end of the cylinder as in a uniflow engine.

In such an engine, another object is to provide a balanced poppet valve, light enough to be opened and closed quickly, one having a large effective opening and excellent flow characteristics, a poppet valve axially symmetrical to the cylinder and permitting a small and symmetrical clearance volume, correctly proportioned for the optimum compression pressure when running condensing under predetermined conditions of high pressure and exhaust pressure. Another object is to provide means for automatically maintaining the clearance volume such that compression will always be substantially correct,

' even if operation should become non-condensing the cylinder cupis evacuated. Another object is to provide construction tending to minimize heat flow from high pressure steam headers to exhaust steam headers, and in general to prevent undesirable heat flow.

Anothercbject is to provide a practical, doubleacting steam engine having no piston rods or piston rod seals, the cylinders and crosshead being combined in one member, reciprocating in the crosshead guides, the pistons being fixed. Other objects are to isolate the working medium from the lubrication oil; and to prevent, so far as practicable, passage of lubricating oil into the cylinder or of the working medium into the casing which houses the mechanism. Reciprocating cylinders, opening away from the mechanism, effectively prevent contamination of the lubricating oil by the working medium and prevent passage of lubricating oil into the working cylinders. Other objects are to provide oil control rings and drainage chambers operable to prevent oil from entering the exhaust header, the means for keeping lubricating oil separate from the working medium operating between the pressure and temperature in the casing which houses the mechanism and exhaust pressure and temperature, not between the casing conditions and those of high pressure steam.

Other'objects are to provide inlet valves in the fixed pistons, pressure balanced poppet valves, of a type permitting rapid opening and closing, with free flow of the steam; to provide an improved valve gear for operating the valves, capable of controlling steam inlet from zero to maximum cutoff, forward or reverse; to use the high steam presure as the valve spring to return the valve to its seat; and to connect the valve operating means at one end of the engine directly to that at the other end, by pull rods thru the slants, making it possible to feed always the same amount of steam in the same way to both ends ofthe engine from a single governor.

These and other objects of the invention will be apparent in greater detail by reference to the drawings in which Fig. l is a longitudinal section of a steam engine constructed in accordance with the invention:

Fig 2 is a transverse section substantially on the lines 2-4! of Fig. l; and

Fig. 3 is a transverse section substantially on the line 33 of Fig. 1.

In the drawings, 'frame members H] are held together upon croshead guide tubes II by thrubolts I2. Reciprocating members 20 are operable arm 3i of starplate 30.

in crosshead guides ll. Each reciper 29 is composed of a crosshead 2| and a pair of cup-shaped cylinders 22 set in the ends thereof, the spaces 25 being evacuated to discourage heat flow from cylinders 22 to crosshead 2|.

Each crosshead 2| has a transverse bore 24 in which pinhead 34 is operable. Wristpin 33 is similarly operable in bushings 35 fixed in pinhead 34, and wristpin 33 is clamped by screws 32 in an The ends of wristpin 33 are spherically adapted to coact with the inner surfaces 23 of crosshead 2| to control correctly the motion of starplate 36. Wristpin 33 is adjustable axially when screws 32 are loosened.

starplate 3B is piloted on spherical boss M splined to shaft 4b, and starplate slippers 36, pivoted on starplate 30, are operable with film lubrication on slants 42, also splinedto shaft 40.

Shaft 49 hasinvolute splines M extending almost its entire length. A single key might be used instead of splines 44. Adjacent the slants G2 on shaft at are collars 43 which operably support and axially locate shaft Ali) and its associated rotating parts in journal bearings i l. Another pair of splined sleeves d5 are also splined to shaft 40, and then the outer journal collars 66, operably supported in journal bearings i5. Nuts 41 at both ends of shaft 80 may clamp all the rotating parts solidly together, the shaft 49 serving as a splined thrubolt with nuts ll at both ends, or with driving flange 58 integral at one end and a single nut 2": at the other end.

at each end of the engine, fixed pistons 50 are supported by cover i1. Covers H and I8 together form steam chest Gil. Piston rings 5| are in grooves in fixed pistons 59, and oil control rings l5 are in grooves in crosshead guides I I, piston rings coacting with the interior cylindrical surfaces of recipers 2b and oil control rings l5 coacting with the exterior cylindrical surfaces, both sets of rings being in substantially the same planes and traversing the same length of recipers 29. Oil wiped oii recipers 20 by oil control rings i5 is drained thru drainage chambers 53.

In each of the 'fiXed pistons 58, is a poppet valve 52, operated by bellcrank 6| and cam follower 62, the latter having a ball or roller 63 coacting with cam 62. Cam 34 is axially slidable on splined sleeve 45, and is tied to another cam 64 at the other end of the engine by tie-rods 65 which pass thru collars 4,3, slants 42, and spherical boss M in a plane at right angles to the plane of these parts in Fig. 1, as indicated in Fig, 3). Both cams 54 are operable by a governor and manual control as usual.

Poppet valve 52 looks like a sleeve and is pressure ba anced, the only unbalanced area being the area of the narrow valve seat when the valve is closed. Poppet valve 52 may be masked or set down into a counterbored seat as shown, to ermit'more rapid effective opening and closing. With this type of poppet valve, clearance chamher 29 may be axially symmetrical and as small as desired for optimum compression pressure.

To adjust clearance chamber 23, displacer piston 53 is operable in cylinder member 54, and may even uncover unloading grooves 55. Outer end of displacer piston 53 is provided wth dashpot piston Eiloosely operable in cylinder 69 and having valve 5? and valve spring 58. All the chamhere 69 are interconnected thru conduit 66 which m y be vented either to outside air or to high 7 pressure steam in steam chest 6i! by vent valve 61.

ciated parts by the operable connection of the starplate mechanism as is well known. Wristpins 33 being tangential to a circle in the plane of starplate as, practically no torque is on starplate 30 and its motion is correctly controlled by the coaction of the spherical ends of wristpins 33 with internal surfaces 23 of crossheads 2!. Oil is fed under pressure thru shaft 453, lubricating slippers 36 as they slip over slants E2, and is fed out thru arms 3! to wristpins 33, pinheads 3i, and crossheads 2 5. Oil control rings [5, assisted by drainage chambers l3, prevent oil from passing into exhaust header chambers 19 and also prevent exhaust steam from passing inwardly into the casing formed between frame members Ill.

With cams 64 in neutral position shown in Fig.

1, no steam is permitted to flow into cylinders 22.

from steam chests 66. Movement of cams B4 axially in one direction will produce admission of steam for forward rotation of shaft fill with increasingly late cutoff, while movement in the other direction produces similar action with reverse rotation of shaft Ml. Cams 64 operate cam followers 63 and 62, bellcranks 6i, and poppet valves 52 to admit steam to cylinders 22 in proper timed relationship for the desired operation. Steam pressure acting on cam followers 62 return them and close valves 52 after the toes of cams 64 have passed. -After closing of a valve 52, the steam in cylinder 22 expands as it moves away from piston 59, until exhaust ports 26, uncover, when discharge takes place thru the exhaust header 58 to the condenser if such there be.

On return stroke of cylinder 22 compression should build up pressure less than that of the high pressure steam in steam chest 60; higher compression would lead to waste as the compressed steam surged thru valve 52 in the wrong direction, delaying inlet of high pressure steam until after cylinder 22 had started away from piston 50. To prevent this, even if operating conditions should change from those prescribed, dis-v placer piston 53 will move away from cylinder 22 if compression pressure exceeds high pressure, increasing clearance volume 29 to prevent overcompression. Immediate return of displacer piston 53 is prevented by the dashpot action of dashpot piston 56 and its valve 51 which permits easy passage of steam into but not out of dashpot chamber 59, suspending displacer piston 53 in whatever position it is pushed by overcompression. However, since the area of the underside of dashpot piston 56 is less than its head area, steam pressure in dashpot chamber 59 will be higher than that in chamber 69, and leakage from chamber 59 to chamber 69 tends to return displacer piston 53 to its normal position with minimum clearance volume 29.

When starting a cold steam engine it is desirable to vent condensate which may form in the cylinders. side air whereupon steam in each cylinder 22 will push displacer piston 53 outward, uncovering unloading grooves 55 permitting flow thru piston 53 to conduit 66 and out thru valve 61. When no more condensate is discharged, valves 6! may be closed, and opened to steam chest Ell, to permit high pressure steam to return displacer pistons 53 to their normal position. Displacer pistons 53 also serve as safety releases to prevent any pressure of steam or liquid in cylinders22 from ever exceeding high steam pressure.

Having thus described the construction and operation of the invention, it is evident that the objects of the invention as stated have been attained Vent valve 6'! may be opened to out-- in a reasonable manner. While a specific embodiment of the invention has been shown and described, it is understood that changes may be made in the construction and operation of the invention without departing from the spirit or scope of the following claims. v

I claim:

1. In a barrel engine mechanism, a reciprocating cylinder member having a double wall, the outer Wall forming a crosshead and the inner wall forming a cylinder bore, a non-reciprocating piston operably received by said cylinder bore,'and ports in the inner cylinder wall, said ports opening axially of said cylinder member into the space around said non-reciprocating piston.

2. In a barrel engine mechanism, a shaft, and reciprocating cylinder members parallel to said shaft, each of said cylinder members being double-walled and including a cylindrical crosshead operably connected to said shaft and a cup.- shaped cylinder mounted in the end of said crosshead with its head and cylindrical walls spaced from the adjacent portions of said crosshead.

3. In an engine mechanism, a shaft, reciprocating cylinder members operably connected to said shaft, and fixed pistons operably received by said cylinder members, each of said cylinder members being double-walled and including a cylindrical crosshead and a cup-shaped cylinder mounted in the end of ,saidcrosshead with a cupshaped closed chamber between said cylinder and said crosshead, said chamber evacuated to diminish heat flow from said cylinder to said crosshead.

4. In a steam engine designed to operate well under prescribed conditions of high pressure steam and condenser vacuum, a reciprocating cylinder member having a cup-shaped cylinder closed at oneend and open at the other, exhaust ports at the open end of said cylinder, a non-reciprocating piston operably received by said cylinder with a certain minimum clearance volume between said piston and the closed end of said cylinder, an inlet valve coaxial with and operably mounted in said non-reciprocating piston, said cylinder and said piston and said valve sov constructed that said clearance volume is axially symmetrical and small enough for optimum compression in said engine under said prescribed conditions, and means movable within said piston for increasing said clearance volume to maintain substantially optimum compression if or when operating conditions change for those prescribed.

5. In a double-acting steam engine of the barrel type having a shaft, double-ended reciprocating members parallel thereto, and mechanism operably connecting said reciprocating members to said shaft: an inlet valve system at each end of said engine, means on and rotating with said shaft for operating each inlet valve system, and tie rods parallel to said shaft and connecting one of said means with the other to compel them to move axially in concert.

6. In a steam engine, a shaft, cylinders parallel thereto, inlet valves for admitting steam to said cylinders, and valve operating mechanism actuated to open said valves by said shaft and to close said valves by steam pressure acting onsaid operating mechanism as valve springs.

'7. In a double-acting steamengine of the barrel type, a shaft, reciprocatingmembers parallel to said shaft, mechanism operably connecting said a reciprocating members to said'shaft, a casing enclosing said mechanism, an exhaust steam chamber, and sealing means coacting with said reciprocating members to prevent the passage of oil or working medium between said casing and said chamber, said sealing means sealing between oil at no pressure and exhaust steam pressure.

' 8. In asteam engine, a shaft, cylinders parallel thereto,ja balanced poppet valve for admitting steam to each of said cylinders, and valve mechanism operable by said shaft and including a cam and a cam follower, said cam follower movable by said cam to open said valve and movable by steam pressure toclose said valve.

, 9. In a steam engine, a reciprocating cylinder rncmber, a non-reciprocating piston operably received by said cylinder member, a balanced poppet valve having the form of a sleeve coaxially operable within said piston member, a sleeve member Within said valve, a piston operable within said sleeve member by the difference between high steam pressure on one end thereof and compression pressure within said cylinder member on the other end thereof.

10. In a steam engine, a reciprocating cylinder member, a non-reciprocating piston operably re- ,ceiVed by said cylinder member, a balanced poppet valve having the form of a sleeve coaxially operable within said piston member, a fixed sleeve member within said valve, a smaller piston operable within said sleeve member-for automatically varying the clearance volume between said cylinder member and said non-reciprocating piston, and means for moving said smaller piston to maintain substantially optimum compression in said reciprocating cylinder member.

11. In a steam engine, a reciprocating cylinder member, a non-reciprocating piston operably'.

smaller piston within said sleeve member.'

EDWIN. S. HALL.

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