US3788193A

US3788193A - Steam engine

Info

Publication number: US3788193A
Application number: US00186069A
Authority: US
Inventors: Connor C O
Original assignee: CONNOR CO
Current assignee: CONNOR CO
Priority date: 1971-10-04
Filing date: 1971-10-04
Publication date: 1974-01-29
Anticipated expiration: 1991-01-29

Abstract

A steam engine of a modified uniflow type having a valve and valve actuating mechanism permitting double-acting cylinders to operate efficiently under high speed-low torque conditions and also to be smoothly adjusted, during engine operation, for lower compression-higher torque operation at low start-up speeds. A chain driven, double cam, valve actuating mechanism permits smooth variations in the timing of valve operation with a simple control system so that even unskilled operators can run the engine, without roughness, through its full speed and torque ranges. A novel cylinder design obtains what is substantially uniflow operation without undesirable high compression.

Description

O Unlted States Patent 1 [111 3,788,193

OConnor Jan. 29, 1974 STEAM ENGINE Primary Examiner-Paul E. Maslousky h 3490 E. [76] Inventor g zgyfi gf gggga Calif Attorney, Agent, or Firm-Wolfe, Hubbard, Leydlg,

91 107 Voit & Osann, Ltd.

[22] Filed: Oct. 4, 1971 [57] ABSTRACT PP NO: 1867069 A steam engine of a modified uniflow type having a v valve and valve actuating mechanism permitting dou- [52] US. Cl. 91/243, 91/187 le-a ing ylinders to operate efficiently under high [51] Int. Cl; F011 21/02, F011 31/14 pe -1 w rque conditions and also to be smoothly [58] Field of Search 91/243, 187, 188 adjusted, during engine p on, or o er compression-higher torque operation at low start-up speeds. A [56] References Cit d chaindriven, double cam, valve actuating mechanism UNITED STATES PATENTS permits smooth variations in the timing of valve opera- 1 076 256 10/1913 91/243 tion with a simple control system so that even un- 1531053 M1925 's 91/243 skilled operators can run the engine, without rough- 1 924 689 8/1933 Knight I: :1: 91/187 6S5, through its full speed and W ranges- A novel 2:688:955 9 1954 Ricardo .7 91/187 Cylinder design Obtains What is Substantially uniflow FOREIGN PATENTS OR APPLICATIONS operation without undesirable high compression. 46,277 7 1939 Netherlands 91 187 4 Claims, 9 Drawing Figures PATENTED JAN 2 91974 SHEET a [If 3 STEAM ENGINE DESCRIPTION OF THE INVENTION This invention relates generally to mechanical power generating steam engines and more particularly concerns a steam engine valving arrangement.

A characteristic of conventional piston type steam engines which has restricted their applications, particularly in recent years, is that good operating efficiency is normally achieved by designing the engine for rather narrow ranges of speed and load. For example, a socalled uniflow type engine in which steam is admitted at the cylinder ends and exhausted at the cylinder center gives good efficiency at relatively high speeds and low torques, because the cylinder ends remain hot, there is high compression, and only short periods of outside emission. However, when such an engine is slowed down and more torque is demanded, efficiency is impaired.

Steam engines for handling wide variations in speed and load, in order to retain reasonable overall efficiency, are therefore normally designed as multiple expansion engines or are otherwise burdened with structural complications, which increase costs and, in themselves, reduce efficiencies.

Accordingly, it is the primary aim of this invention to provide a steam engine capable of operating very efficiently under high speed-low torque conditions but which can be smoothly adjusted for low speed-high torque operation without roughness. As a result of the above operating characteristic, the engine of the invention is well suited for use as the propeller power plant for boats since cruising speed efficiency is obtained without sacrificing low speed maneuvering ability.

Another object of the invention is to provide an engine of the above type which is relatively uncomplicated and hence economical to manufacture and maintain. i

A further object is to provide, in an engine as characterized above, a simple, easily understood control arrangement by which the engine can be safely and efficiently operated even by relatively inexperienced personnel.

It is also an object to provide anengine of the above kind having the advantages of uniflow operation without undesirably high compression.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in

which:

FIG. 1 is a fragmentary partially sectioned elevation of a steam engine embodying the invention;

FIG. 2 is a section taken approximately along the line 22 in FIG. 1;

FIG. 3 is a section taken approximately along the line 33 of FIG. 1;

FIG. 4 is a partially schematic perspective showing a portion of the structure appearing in the previous figures;

FIG. 5 is an enlarged elevation of one of the cams developed in the engine of FIG. 1; and

FIGS. 6, 7, Band 9 are stop motion views similar to FIG. 1 showing the parts in different positions of operation. I

While the invention will be described in connection with a preferred embodiment, it will be understood that I do not intend to limit the invention to that embodiment. On the contrary, I intend to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention.

Turning now to the drawings, there is shown a steam engine 10 embodying the invention but which is only partially illustrated for clarity and simplicity of description. The engine 10 includes a main bed plate 11 supporting a cylinder head 12 receiving a reciprocating piston 13 coupled to a power output crank shaft 14 and which is operated by a valve 15 driven by a timing assembly 16. The assembly 16 is supported on a'frame plate 17, fixed to the bed plate 11, which also journals the crank shaft 14 in bearings 18. The crank shaft is associated with a fly wheel, not shown, and the primary power utilization device, such as a boat propeller.

Although only one cylinder head 12 and valve 15 is illustrated, it will be apparent that additional heads and valves may be alined along the crank shaft 14 to make the engine 10 multi-cylindered. As those skilled in the art will appreciate, the connections between the crank shaft and additional cylinders would be angularly phased so as to smooth out the application of power to the crank shaft.

The piston 13 is coupled to the crank shaft 14 through a rod 21 pivoted on a crank 22 that is journalled on an eccentric section 23 of the crank shaft 14.

The cylinder head 12 includes a block 24 defining a cylinder 25 and a valve chamber 26 whose opposite ends are sealed by head and base castings 27 and 28. The engine 10 is double-acting and hence both castings 27, 28 define, together with side plates 29, steam supply passages 31 for conveying steam in the direction of the arrows 32 (see FIG. 1) to the opposite ends of the valve chamber 26. I

Pursuant to one aspect of the invention, the cylinder 25 is of a modified uniflow type having steam admission ports 41 and 42 at each end, a primary steam exhaustion port in the form of a number of small openings 43 at the cylinder middle, and a pair of auxiliary exhaustion ports 44 and 45 at intermediate portions of the cylinder between the primary exhaustion port openings 43 and the admission ports 41, 42. Cooperating with these ports is a spool-like valve element 46 slidably titted in the valve chamber 26 and having a pair of land portions 47 and 48 spaced for alternately opening the admission ports 41,- 42 while keeping the primary exhaustion port openings 43 open and simultaneously opening and closing the auxiliary port 44 or 45 farthest from the then open admission port.

The functioning sequence can be readily seen in FIGS. 6 through 9. In FIG. 6, the engine 10 is stopped and both admission ports 41, 42 are closed. Movement of the valve element 46 upwardly, as to the-position shown in FIG. 7, opens the admission port 42 so as to admit steam and drive the piston 13 upwardly and the engine in a given direction. Movement of the valve element 46 downwardly from its FIG. 6 position would. have started the piston 13 in a downward direction and the engine in the reverse direction. With the valve element 46 in its FIG. 7 position, the auxiliary port 44 is also open venting the upper half of the cylinder through the center portion of the element 46 and out to an exhaust passage 49 defined by an element 51 secured to the block 24.

After the valve element 46 remains in its FIG. 7 position for abrief time period, the length of which deterhave been cleared by the piston. The return down- I stroke of the piston 13 is initiated by movement of the valve element 46 down to the FIG. 9 position in which the admission port 41 is opened as well as the auxiliary exhaustion port 45. After a timed amount of steam is admitted to the upper end of the cylinder 25, the valve element 46 is again centered and the cycle repeated. Those familiar with this art will recognize that the engine 10 has substantial similarity to the uniflow type of engine in that steam exhaustion takes place at the middle of the cylinder thus keeping the ends of the cylinder hot and permitting relatively high compression buildups which are, of course, factors that make a uniflow engine efficient during high speed-low torque operation. It will be noted that movement of the valve element 46 through its FIG. 6 to FIG. 8 positions during a short time interval will admit only a small amount of steam into the lower end of the cylinder-25 and will also quickly close off the auxiliary exhaustion port 44 so as to obtain a virtually classic uniflow operation.

On the other hand, for example when low speed-high torque operation is called for, the valve element 46 can be left in its FIG. 7 position for a longer time interval with the result that more steam is admitted for powering the upward stroke of the piston 13 and the auxiliary exhaust port 44 is left open for a greater length of time to minimize the compression against which the piston must act.

In accordance with the invention, the timing assembly 16 moves the valve element 46 from its center blocking position to, alternatively, its two admission port opening positions for finite periods of time, measured against crank shaft rotation, that may be varied while the engine is running. In the illustrated embodiment, the valve element 46 is connected by a slide rod to a whiffle tree 56 at a pivot point 57. The opposite ends of the whiffle tree 56 are pivoted to ears 58 on a pair of box cam followers 59 embracing, and riding on, the top and .bottom peripheries of a pair of identical earns 61 and 62 rotating with cam shafts 63 and 64, re-

is coupled by apair of gears 65 (see FIG. 4) to a valve shaft 66 having keyed thereto a pair of sprockets 67 and 68. A chain 69 couples the sprocket 67 to a sprocket 71 keyed on the camshaft 64. A second chain 72 couples the sprocket'68 to a sprocket 73 keyed on the other cam shaft 63. The chains 69, 72 are trained over idler sprockets 74 running freely on their respective supports, including an idler shaft 75 and a pair of blocks 76 and 77. The illustrated arrangement also includes a third chain 78 and a pair of sprockets 79 for driving an auxiliary power shaft 81.

In carrying out the invention, each cam 61, 62 (see FIG. 5) has high and low peripheral portions defined by a segment 82 of a smaller base circle, having a radius 84, and a segment 83 of a larger dwell circle, having a radius 85, disposed 180 apart, with the remainder of the cam periphery being arcs smoothly fairing into the circle segments 82, 83 so that the cam has the same dimension between all parallel lines tangent to the pcriphery, such as the line pairs 86 and 87. Because of this uniform peripheral cross dimension, the earns 61, 62 fit closely within the box followers 59 in all angular positions of their supporting cam shafts 63, 64.

The earns 61, 62 as shown in FIG. 3, are 90 out of phase but it can be seen that when the cams are out of phase the valve element 67 will not be moved from its center, port blocking position upon rotation of the cam shafts 63, 64 as, in that situation, the whiffle tree 56 will simply be rocked by the box followers 59 moving up and down in exact but opposite sequence. However, by-varying the angular phase relationship between the cams 61, 62 up to the point where the cams are in phase, the upper or ear portions of both box followers will, for a given interval of cam rotation, ride on the dwell circle segments 83 of both cams and on the base circle segments 82 of both cams. When on the dwell circle segments, the valve element 67 will have been lifted to its FIG. 7 position, and when the ear portions of the box followers'59 ride on both base circle segments 82, the valve element 46 will have been shifted down to its FIG. 9 position. At other times the valve element is in movement or held in its port blocking, FIGS. 6 and 8 position.

In order to shift the angular phaserelationship of the cams 61, 62 whether or not the engine is running, the chain 72 has substantial slackness and the block 76 supporting the idler sprockets 74 is shiftable so as to vary the effective length of chain in the opposite runs connecting the sprockets 68 and 73. This obviously changes the cam angular phase relationship. In the illustrated arrangement, a simple rod 90 threaded through a lug 91 mounted on the plate 17 is provided for shifting the block 76. l

To get the engine started in the desired rotational direction, that is in forward or reverse, the chain 69 also has substantial slackness and an actuator 92, anchored to the lug 91, is provided to-shift the idler block 77 between two limit positions. This movement is sufficient to rotate the cam shaft 64 180 with respect to the crank shaft 14 so as to thereby reverse engine rotation when steam is again supplied to the engine.

While the cams 61, 62 for the application illustrated have their circular segments 82, 83 of substantially equal angular length so that each admission port 41,42 is opened approximately the same length of time for a given crank shaft speed, it will'be seen that using a cam of this shape toconvert rotary t'o reciprocating motion results in anarrangement wherein the extentof reciprocating motion that is developed is the difference between the radii 84, 85, and the pause or dwell time created by the cam is dependent upon the relative angular lengths of the circular segments 82, 83. Theselengths obviously need not be of similar angular extent, and hence the shape of the cams 61,62 permits significant versatility of design.

It will be apparent from the foregoing that simple adjustment of the threaded rod 90 can change, during engine operation, the engine valve cut-off" time so as to produce the flexibility of valve settings discussed above in connection with FIGS. 6 through 9. For example, during engine startup under relatively high torque, the adjustment of the rod 90 would normally be such to leave the appropriate steam admission port and corresponding auxiliary exhaustion port open for a substantial number of degrees of crank shaft rotation. Once higher speeds and lower torque. requirements are reached, the rod 90 may be readjusted to achieve the uniflow typeof operation discussed above thereby taking advantage of the efficiency inherent in such a design.

It will have been noted that the cams 66, 62 of the timing assembly 16 not only permit variation in valve timing while the engine is running, but that this adjustment is infinitely variable'through a wide range. Stated in terms often used in the art, the assembly 16 controls the ratio between the admission and the expansion portions of each cycle and cut-off, the event dividing admission and expansion, is infinitely variable. As a result, the engine can be readily adjusted for optimum efficiency.

Those familiar with this art will appreciate that the engine 10 is of a straightforward, relatively uncomplicated design and hence economical to manufacture and maintain.

1 claim as my invention:

1. In a steam engine, the combination comprising, a cylinder head defining a cylinder with a steam admission port at one end and a steam exhaustion port at an intermediate portion of the cylinder, a piston fitted for reciprocation in said cylinder, a crank shaft coupled to said piston so that reciprocation of the piston rotates said shaft, said cylinder head defining a valve chamber adjacent said cylinder with a steam inlet passage adjacent said admission port and a steam discharge passage adjacent said exhaustion port, a valve element mounted in said chamber for movement between a first position in-which said ports are blocked to a second position in which said ports are opened to the respective adjacent passages, a pair of identical cams each having high and low portions coupled to be driven by said crank shaft, a whiffle tree connected to said valve element and riding on said cams so that when the cams are 180 out of phase the valve element is not moved out of said first position as the whiffle tree is rocked by the cams, and means for varying the angular phase relationship between said cams so that, for every full revolution of the cams, the whiffle tree rides for finite periods of time depending on said phase relationship on both of said high portions and on both of said low portions whereby the whiffle tree moves the valve element to said second position for one of said periods of time.

2. The combination of claim 1 in which said means is effective for smoothly and continuously varying said phase relationship while said crank shaft is rotating so as to permit adjustmentof the time period said valve element is in said second position from zero to a maximum value while the engine is running.

3. The combination of claim 2 in which said crank shaft drives ones of said cams, and said means includes a chain coupling sprockets mounted for rotation with both of said cams, said chain having substantial slackness, and said means also including a pair of mutually shiftable idler sprockets positioned for taking out said chain slackness, whereby mutually shifting said idler sprockets varies the angular phase relationship between said cams.

4. The combination of claim 1 in which said cylinder has steam admission ports at each end and a pair of steam exhaustion ports at mid-portions of the cylinder, said valve chamber having steam inlet passages adjacent each of said admission ports and a steam discharge passage adjacent both of said exhaustion ports, said valve element having a first position in which all of said ports are blocked, a second position in which one admission port is open' to the adjacent inlet passage and one exhaustion port is open to the adjacent discharge passage, and a third position in which the other admission port and exhaustion port are opened to their adjacent passages, and said cams having their high and low portions of equal angular length so that, when the cams are not 180 out of phase, the valve element is shifted tions.

Claims

1. In a steam engine, the combination comprising, a cylinder head defining a cylinder with a steam admission port at one end and a steam exhaustion port at an intermediate portion of the cylinder, a piston fitted for reciprocation in said cylinder, a crank shaft coupled to said piston so That reciprocation of the piston rotates said shaft, said cylinder head defining a valve chamber adjacent said cylinder with a steam inlet passage adjacent said admission port and a steam discharge passage adjacent said exhaustion port, a valve element mounted in said chamber for movement between a first position in which said ports are blocked to a second position in which said ports are opened to the respective adjacent passages, a pair of identical cams each having high and low portions coupled to be driven by said crank shaft, a whiffle tree connected to said valve element and riding on said cams so that when the cams are 180* out of phase the valve element is not moved out of said first position as the whiffle tree is rocked by the cams, and means for varying the angular phase relationship between said cams so that, for every full revolution of the cams, the whiffle tree rides for finite periods of time depending on said phase relationship on both of said high portions and on both of said low portions whereby the whiffle tree moves the valve element to said second position for one of said periods of time.

2. The combination of claim 1 in which said means is effective for smoothly and continuously varying said phase relationship while said crank shaft is rotating so as to permit adjustment of the time period said valve element is in said second position from zero to a maximum value while the engine is running.

4. The combination of claim 1 in which said cylinder has steam admission ports at each end and a pair of steam exhaustion ports at mid-portions of the cylinder, said valve chamber having steam inlet passages adjacent each of said admission ports and a steam discharge passage adjacent both of said exhaustion ports, said valve element having a first position in which all of said ports are blocked, a second position in which one admission port is open to the adjacent inlet passage and one exhaustion port is open to the adjacent discharge passage, and a third position in which the other admission port and exhaustion port are opened to their adjacent passages, and said cams having their high and low portions of equal angular length so that, when the cams are not 180* out of phase, the valve element is shifted for equal time periods into said second and third positions.