US3668974A

US3668974A - Reciprocating engine

Info

Publication number: US3668974A
Application number: US6503A
Authority: US
Inventors: Manfred Otto Hagdorn; Kjell T-Son Sandberg
Original assignee: Electrolux AB
Current assignee: Electrolux AB
Priority date: 1969-01-29
Filing date: 1970-01-28
Publication date: 1972-06-13
Anticipated expiration: 1989-06-13
Also published as: DE2003923A1; FR2029626A1; GB1281328A; CA933821A

Abstract

This invention relates to a reciprocating engine which operates with a compressible working medium like steam and has a cylinder and a cooperating cylinder head. A piston moves forward and backward in the cylinder space. Steam is supplied under pressure to an outer space in the cylinder head and the flow of such steam to the cylinder space is controlled by a valve responsive to the pressure of the steam. In order to regulate the flow of steam into the cylinder space in the first part of each forward stroke of the piston, the valve is acted upon and closed by steam under pressure which becomes available to perform this function when the piston reaches a particular position in each forward stroke.

Description

Unite States atent Hagdorn et a1.

[ 1 June 13, 1972 [54] RECIPROCATING ENGINE [72] Inventors: Manfred Otto Hagdorn, Stockholm; Kjell T-Son Sandberg, Taby, both of Sweden [73] Assignee: Aktiebolaget Electrolux, Stockholm,

Sweden 22 Filed: Jan. 28, 1970 21 Appl. No.: 6,503

[30] Foreign Application Priority Data Jan. 29, 1969 Sweden... ..1174/69 Dec. 16, 1969 Sweden ..17298/69 [52] US. Cl ..91/242, 91/299, 91/325 [51] Int. Cl. ....E0ll 25/06, E011 21/02 [58] Field ofSearch ..9l/278,224,299, 242, 325

[56] References Cited UNITED STATES PATENTS 1,804,216 5/1931 Gustafson ..91/278 1,911,978 5/1933 Uhler et a1. ..91/278 2,100,541 1 1/1937 Gartin ..91/278 3,361,036 1/1968 Harvey et a1 ..91/224 FOREIGN PATENTS OR APPLICATIONS 1,042,607 11/1958 Germany ..91/299 Primary Examiner-Paul E. Maslousky Attorney-Edmund A. Fenander [5 7] ABSTRACT This invention relates to a reciprocating engine which operates with a compressible working medium like steam and has a cylinder and a cooperating cylinder head. A piston moves forward and backward in the cylinder space. Steam is supplied under pressure to an outer space in the cylinder head and the flow of such steam to the cylinder space is controlled by a valve responsive to the pressure of the steam. ln order to regulate the flow of steam into the cylinder space in the first part of each forward stroke of the piston, the valve is acted upon and closed by steam under pressure which becomes available to perform this function when the piston reaches a particular position in each forward stroke.

10 Claims, 5 Drawing Figures CONDENSER PATENTEDJUN13 m2 3, 568,974

v SHEET 1 BF 3 CONDENSER PAT NTEuJum m2 CONDENSER E Me M7 SHEET 2 OF 3 PATENTEDJUN 13 1972 3. 668 974 sum 3 OF 3 CONDENSER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to reciprocating engines which operate with a compressible working medium like steam to produce power which makes it available as a rotating torque at a crankshaft or flywheel.

2. Description of the Prior Art For a long time reciprocating engines have been developed for converting heat to rotating torque with steam as the working medium. Such engines have been designed mainly for large outputs and information on the fundamental principles of such engines can be obtained from general handbooks. Later, combustion engines become available which were built in small units suitable for propelling vehicles. These engines have been developed to such a degree that, because of the small space required, they now are almost the only source of power for automobiles.

' To an increasing degree modern military equipment requires electric power to operate such equipment. For driving electric generators to provide a source of electrical energy for military purposes, it is desirable to employ portable sources of power which are silent. For this reason, it has been proposed to employ small portable reciprocating engines for military purposes which work with a compressible medium like steam. Since these engines are designed primarily to drive electric generators they have been constructed to operate at their highest coefficient of efficiency and output at essentially constant r.p.m. determined by the requirements of the generator.

SUMMARY OF THE INVENTION It is an objectof our invention to provide an improved reciprocating engine which operates with a compressible working medium like steam to produce power which makes it available as a rotating torque, the speed and power of the engine being variable over wide limits. 7

We accomplish this by supplying a compressible working medium like steam to an outer space in a cylinder head and controlling the flow of such steam to a cylinder space by a valve responsive to the pressure of the steam. In order to regulate the flow of steam into the cylinder space in the first part of each forward stroke of the piston moving forward and backward in the cylinder space, the valve is acted upon and closed by steam under pressure which becomes available to perform this function when the piston reaches a particular position in each forward stroke.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawing,

FIG. 1 is a vertical sectional view of a one-cylinder engine embodying our invention which is normal to its crankshaft and adapted to be operated .with a compressible gaseous medium like steam, for example;

FIG. 2 is a fragmentary sectional view of parts like those shown in FIG. 1 illustrating another embodiment of the invention;

FIGS. 3 and 4 are fragmentary sectional views similar to FIG. 2 illustrating other embodiments of the invention; and

FIG. 5 is a vertical sectional view of an engine like that shown in FIG. 1 illustrating a further embodiment of the invention.

Engines of this type have a very limited field of use and are 2 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the reciprocating engine embodying our invention comprises a crankshaft 10 which operates in a crankcase 11 and is connected by a connecting rod 12 and a piston pin 13 to a piston 15 which operates in a cylinder 14 and is provided with piston rings 17 disposed in annular grooves 16. Although not shown, the inner wall of the cylinder 14 can be provided with a lining of suitable material, such as carbon steel, for example, having desirable heat conductive and lubricating properties. An intermediate wall 19 is arranged between the upper end of the cylinder and a cylinder head 18 in such manner that it forms a partition between the cylinder space 20 and an outer space 21 in the cylinder head 18.

The outer space 21 is connected by a conduit 22 to a source of supply of steam or other suitable compressible gaseous medium (not shown), so that the space 21 will always be at the same pressure as the steam which is supplied thereto. In FIG. 1, the moving parts of an inlet valve are disposed above an opening 23 in the intermediate wall 19 which is concentric with the cylinder 14 and has a diameter d.

The outer surface of the intermediate wall 19 serves as a seat for a valve body comprising a valve disc 24 which is connected by one or more rods 25 to a piston-

shaped part

27,28 which is movable in an annular cavity 26 in the cylinder head 18 in a direction toward and from the valve seat. The part 27 is cylindrical and adapted to bear and seal against the outer wall of the cavity 26 and the part 28, which is urged in a direction from the valve seat by the pressure of the steam in the chamber 21, has substantially the same area as that of the opening 23 which has the diameter d and with which the inlet valve coacts.

In FIG. 1 the inlet valve is shown in its closed position, that is, with the valve disc 24 bearing against the valve seat. Since the area of the part 28 subjected to the steam pressure in chamber 21 and having the diameter D substantially corresponds to the area of the opening 23 which has the diameter d, the steam in the chamber 21 exerts no opening pressure on the valve body but the valve is kept in its closed position by a small force produced by a pressure spring 30 which is concentric with the valve body and disposed in a space 29 in the cylinder head 18. If it should be desirable to employ the steam in chamber 21 to maintain the valve in its closed position, this can be done'by providing a valve disc 24 and opening 23 therefor which are correspondingly larger than the area of the part 28 which has the diameter D. I

The quantity of steam which flows into the cylinder space 21. during each stroke of the piston is determined by a conduit 33 having one end open at 34 in the cylinder space 20 and the opposite end open at 35 in the space 29 of the spring 30 which tends to keep the valve in its closed position. The space 29 is in communication with the annular cavity 26 in the cylinder head 18.

When the piston moves from its upper dead center position toward its bottom dead center position during a working stroke, it uncovers the opening 34 of the connecting conduit 33 so that steam at essentially the pressure of the inlet steam flows through the conduit 33 into the space 29 and balances the steam pressure acting on the opposite bottom side of the part 28 of the valve body, whereby the steam pressure acting on the parts of the valve system become balanced and the spring 30 functions to close the valve.

While opening 34 of the connecting conduit 33 can be located at such a particular point that the best filling of steam in the cylinder space 20 will be obtained at a certain r.p.m. and with a certain load on the engine, the location of the opening 34 at such particular point will not give an equally good result at varying loads and speeds. Therefore, the conduit 33 includes a plurality of

branch conduits

37,38,39,40 which are connected in parallel and can be connected to the conduit 33 by a selector 36. The branch conduits 37,38,39 and 40 having o

enings

34,4l,42,43 communicating with the cylinder space 20 which are located at different distances from the dead center position of the piston 15. The selector 36 comprises a casing 44 within which is disposed a rotatable ring 46 having an opening 47 which can be selectively placed in communication with any one of the

branch conduits

37,38,39,40.

The engine illustrated in FIG. 1 operates like a direct current engine, that is, the working medium is admitted into the s ace 20 when the piston is in its top dead center position and is discharged therefrom when the piston is close to its bottom dead center position. The outlet for the working medium is formed by one of several ports in the wall of the cylinder 14. I During the working stroke, the working medium expands during movement of the piston 15 from its top dead center position toward its bottom dead center position. When the top piston ring 17 of the piston 15 passes the edge 49 of a port 48, the more or less expanded working medium commences to flow from the space through the port. Such outward fiow of the working medium continues while the piston moves downward and then moves upward until the piston ring 17 passes the edge 49 of the port during upward movement of the piston 15 to its top center position.

While the piston 15 is moving downward during its working stroke with the inlet valve closed, the pressure of the steam decreases in the cylinder space 20 and also in the conduit 33 and for this reason, during this entire period, the steam pressure in the cylinder space 20 at the bottom of the valve disc 24 balances the pressure transmitted from the connecting conduit 33 to the outside of the piston-

shaped part

27,28 of the valve.

While the piston 15 is moving toward its top dead center position a loss by compression would occur if an outlet valve 50 like that shown in FIG. 1 were not provided. The outlet valve 50 is connected to an opening 51 in the wall of the cylinder 14, such opening having its upper edge 52 located at a somewhat greater distance from the intermediate wall 19 than the distance therefrom to the top piston ring 17 when the piston 15 is in its top dead center position.

The outlet valve 50 comprises a valve disc 53 which, during the working stroke, is moved against a valve seat 54 by the pressure of the steam in the space 20 against the action of a pressure spring 55 which is adjusted so that it will be capable of moving the valve disc 53 from its seat 54 against the action of the exhaust pressure in the space 20 during the exhaust stroke of the piston 15. In this way losses resulting from compression work in the engine that is not utilized are prevented.

The position of the opening 51 in the cylinder wall can be selected so that the valve, after the piston 15 has passed the opening, causes a certain compression of the body of steam enclosed in the space 20 so that a pressure on the inlet valve is produced which lifts the valve disc 24 a small amount. When this occurs, inlet steam flows from the space 21 into the cylinder space 20 and the pressures on the top and bottom sides of the valve disc 24 are equalized and the pressure of the inlet steam in the space 21 on the part 28 of the valve body will lift the valve disc 24 completely from its seat and steam will flow into the cylinder space 20 and cause the piston 15 to move downward toward its bottom dead center position while the steam is expanding.

The reciprocating steam engine just described and shown in FIG. 1 is characterized by the absence of any venting provisions to the atmosphere which is costly. This is so because the valve body, which includes the

pistonshaped parts

27 and 28, would not be balanced on steam under pressure if the valve body were vented to atmosphere. As seen in FIG. 1, therefore, the outer space 21 is sealed from the atmosphere, and, as pointed out above, this space will always be at the same pressure as the steam which is supplied thereto.

Further, by providing the connecting conduit or passageway means 33 exteriorly of the cylinder wall 14 and only extending the horizontal passageway means 37 to 40 through the cylinder wall the volume of the dead spaces in communication with the cylinder space 20 is at a minimum. The manually operable selector 36 interposed between the vertical conduit 33 and horizontal passageway means 37 to 40 provides an arrangement which enables the reciprocating engine to be driven at various speeds which can easily be controlled manually by the handle of the selector or control 36.

The steam inlet arrangement shown in FIG. 1 and just described can be varied in many ways within the scope of our invention. FIG. 2 illustrates a modification in which a plurality of openings 60 are provided between the outer space 121 and the cylinder space 120. Parts in FIG. 2 which are similar to parts in FIG. 1 are designated by the same reference numerals to which is added. Over the intermediate wall 119 is positioned a valve disc 124 which is in the form of a clover leaf having the same number of leaves as the number of openings 60. Between adjacent leaves is provided a pin 61 that prevents rotating movement of the valve disc 124. The part 128 of the valve body is of conical shape and is guided in a space 129 in which the spring is disposed. An adjusting screw 62 coacts with the spring 130 to adjust the force of the spring.

The selector 136 is provided with an inner sleeve 146 turnable by an arm 63. The sleeve 146 is provided with a plurality of openings 147 which are so positioned that, by turning the arm 63, the conduit 133 can be connected to any one of the branch conduits having openings 141,142 and 143 in communication with the cylinder space 120. The valve body 124,128 consists of separate parts which are connected by a sleeve 64 threaded on a tap 65 fixed to the part 128. The sleeve 64 has an inner shoulder 66 for the spring 132 and an outer shoulder 67 against which the valve disc 124 and a cylindrical part 68 rest. The inlet valve arrangement shown in FIG. 2 operates in the same way as the corresponding inlet valve arrangement shown in FIG. 1 and just described.

As in the first-described embodiment the outer space 121 in FIG. 2 is sealed from the atmosphere. Further, the volume of the dead spaces in communication with the cylinder space 121 is still at a minimum for the reason that only a single vertical passageway 133 extends downward from the cylinder head 1 18 to the manually operable control or selector 136.

Another modification of an inlet .valve arrangement is shown in FIG. 3 in which certain parts are similar to parts in FIG. 1 and other parts are similar to parts in FIG. 2. In FIG. 3 the valve disc 224 is like the valve disc 124 in FIG. 2 and the remainder of the valve body is disposed in a space 226 about a central space 229 in which the spring 230 is located. The pressure of the inlet steam in the space 221 acts upon a surface 70 having an area corresponding to the area of the openings 260. The valve body 71 also has a wider part 72, the inner or upper side of which is subjected to the pressure in the connecting conduit 233, so that a greater closing force acting on the valve can be obtained. One of the cylindrical parts 71' and 72 of the valve body 71 or both of these parts can slide sealingly against an outer sealing ring 70' during the movement of the valve body.

A further modification of the inlet valve arrangement is shown in FIG. 4. In FIG. 4 a valve disc 80 of steel is fixed to a central tap 81 which in turn is connected to a diaphragm 82, the peripheral edge portion of which is fixed in the cylinder head 318. The spring 330 bears against a central portion of the diaphragm 82 which can be made of suitable resilient material or of metal and also can be formed like a bellows. An adjustable throttle device comprising a screw 83 is provided in the conduit connection 333. This is suitable in the case of a reciprocating engine that operates with a constant filling of steam or other working medium.

When a stationary one-cylinder engine having an inlet valve arrangement embodying our invention is started, the crankshaft 10 is rotated so that the piston moves upward to a position suitable for starting. When the piston is in such starting position the inlet valve is opened by suitable mechanism which can be operated electrically, mechanically or pneumatically, for example. By way of example, an electromagnet (not shown) can be employed to open the inlet valve. In the embodiment shown in FIG. 1, a spring 32 is provided at the bottom of the valve'disc 24 so that the top surface 31 of the piston 15, during upward movement of the piston toward its top dead center position, will act on the spring 32 and lift the valve disc a small amount. After this occurs the pressure of the inlet steam will cause the valve to open completely.

In the modification of FIG. 3 is shown an arrangement for starting the engine pneumatically. A space 73 exteriorly of the valve piston 71 is connected by a conduit 74 to a condenser which prevents a pressure build-up in the space 73 during operation of the engine. However, during starting of the engine the pressure medium can be admitted in the space 73 to effect lifting of the valve disc 224. It is also possible to start the engine with a negative pressure from the condenser at the opposite side of the piston.

When a starting device is actuated by a suitable impulse, it is desirable either to control the position of the piston in order that starting will be initiated with the piston in a proper stating position, or to employ an automatic device which prevents starting of the engine when the piston is not in a proper starting position. In a one-cylinder engine like that shown and described, a flywheel provided with a suitable marking can be turned to a proper starting position. Absence of compression in the engine will not prevent such movement of the flywheel.

In a multiple-cylinder engine there will always be some piston in a proper starting position for starting the engine. Under these conditions the starting device desirably should be combined with a sensing instrument to indicate which one of the engine cylinders must be supplied with steam to start the engine. An arrangement of this kind can be provided which will function automatically to start the engine.

A starting device of the kind referred to in connection with FIG. 3 is diagrammatically shown in detail in FIG. 5. In FIG. 5 a piston 411 having piston rings 412 is adapted to reciprocate in a cylinder 410. Outside the cylinder an outer space 413 is provided to which a compressible medium like steam, for example, is supplied through a conduit 414. An intermediate wall 415 between the cylinder 410 and the outer space 413 has an opening 416 adapted to be closed by a valve disc 417 forming part of an inlet valve. The valve disc 417 is connected by a bolt 418 to a valve body 419 which is vertically movable and includes a first cylindrical part 420 sealingly arranged against an outer ring 421 and a second wider cylindrical part 422 sealingly arranged against a corresponding surface of the ring 421. Thediameter of the cylindrical part 420 is desirably such that the steam pressure in the outer space 413 on the valve disc 417 in a downward direction toward the valve seat and the steam pressure in the upward opposite direction on the valve body 419 are balanced. The valve disc 417 is biased toward its valve seat by a'centrally disposed spring 423 arranged in a chamber 424.

When the engine shown in FIG. 5 is being operated the inlet valve 417,419 opens due to the steam compression produced in the cylinder space 410 during the latter part of the upward movement of the piston 411. When the valve 417, 419 has opened a small amount the balancing of the steam pressures on the valve body 419 ceases and the valve will move to its wide open position and steam will flow into the cylinder space 410. Downward movement is imparted to the piston 411. Thereafter the conduit connection established between the cylinder space 410 and the spring chamber 424 will cause the inlet valve 417,419 to close at a particular time.

The conduit connection just referred to includes a passageway 425 between the spring chamber 424 and a space 426 in which a sleeve 428 is rotatable by a handle 427. The sleeve 428 is provided with a plurality of openings 429 which are provided along a helical line and the cylinder wall 430 is formed with a series of

channels

431, 432, 433, 434, 435 which are located at different distances from the intermediate wall 415.

The degree of filling of the cylinder, that is, the quantity of steam admitted into the cylinder space 410 for each working stroke of the piston 411, can be determined by adjusting the rotatable sleeve 428 by the handle 427. In FIG. 5 the sleeve 428 is in such a position that one of the openings 429 communicates with the channel 433 in the cylinder wall 430. Under these conditions steam will flow into the cylinder space 410 during downward movement of the piston 411 until the top piston ring 412 has passed the channel 433.

When this occurs steam from the cylinder space 410 will flow through the channel 433, an opening 429, space 426 and passageway 425 to the spring chamber 424. In chamber 424 the valve body 419 will be subjected to this steam pressure and impart downward movement to the valve 417,419 419 and close the opening 416. The valve diaphragm 417 moved downward on its seat very quickly and cuts off the admission of steam into the space in a manner which, to a great extent, is independent of the r.p.m. of the engine. The steam present in the cylinder 410 expands during the downward movement of the piston 411 until the top piston ring 412 has passed the edges 436 of a plurality of outlet openings 437 leading to an annular space 438 having an outlet 448' in communication with a condenser.

An outlet valve 450, which is like the outlet valve 50 in FIG. 1 and described above and serves the same purpose, is connected to an opening 451 in the wall of the cylinder 430. The outlet valve 450 comprises a valve disc 453 which, during the working stroke, is moved against a valve seat 454 by the pressure of the steam in the space 410 against the action of a pressure spring 455 which is adjusted so that it will be capable of moving the valve disc 453 from its seat 454 against the action of the exhaust pressure in the space 20 during the exhaust stroke of the piston 411.

Exteriorly of the valve body 419 in the cylinder head 439 and between the valve body and the sealing ring 421 is provided a space, 440 to which is connected one end of a passageway 441,444, the other end of which is connected to the annular passageway 438. If desired, the lower end of the passageway 441,444 can be connected directly to the condenser in communication with the annular passage 438. In this way the valve body 419 is prevented from being subjected to any pressure tending to impede its movement.

In accordance with our invention the space 440 is employed to start the reciprocating engine. As shown, a passageway 442 is provided in the cylinder head 439 which extends between the passageway 441 and the outer space 413 in which the inlet steam pressureprevails. A push rod 443 having a sealing ring 449 is axially movable in the passageway 442. When the push rod 443 is moved inward, the sealing ring 449 closes the passageway 441 so that passageway 444 which is associated therewith, no longer will be connected-to the annular passage 438. The push rod 443 is provided with a valve device or disc 446 disposed in an inner enlarged portion 445 of the passageway 442. When the push rod 442 is moved inward valve device or disc 446 moves from its seat a small amount to establish communication between the inlet steam space 413 and the space 440. When this occurs the steam under pressure functions to move the valve device or disc 446 to its wide open position. In order to maintain the sealing ring 449 and valve device or disc 446 in the positions illustrated in FIG. 5 with the connection 441,444 to the annular passage 438 or condenser open and the connection from the outer steam inlet space 413 to the space 440 closed, a spring 447 is disposed between the cylinder head 439 and a pair of lock nuts 448 on the push rod Steam under pressure flows from the inlet steam space 413 to the space 440 only when the piston 411 is in a proper position whereby the steam admitted under pressure into the cylinder space 410 will be capable of moving the piston in the intended direction. In accordance with our invention structure can be provided which is dependent upon the positions of the piston 411 and the crankshaft and operatively associated with the valve device or disc 446 so that the valve device cannot be opened by the pressure of steam in the steam inlet space 413 until the piston is in a proper position for starting the engine.

In a multiple-cylinder engine, there is always one piston in a proper position for starting the engine. In accordance with our invention, therefore, the engine can be equipped with a lowpressure connection from the steam inlet space 413 to the space 440 and with a connection from the steam inlet space 413 to each cylinder and the starting device can be provided with structure which is dependent on the position of the crankshaft whereby, when the engine is started, steam from the inlet steam space 413 will automatically flow into the space 440 near that piston which is in the most proper starting position.

The reciprocating engine just described has many interesting characteristics. Due to its simple construction the engine has relatively small dimensions for a given output. By reason of its simplicity it is easy to handle and is safe in operation and its operating qualities make it usable for most purposes requiring a source of power. It can be so balanced that it operates with only slight vibrations. The engine can readily be manufactured with a plurality of cylinders whereby the torque on the crankshaft will be more even than in a one-cylinder engine.

When a combustion engine of an automobile is replaced by an engine of the kind herein described, the qualities of the engine embodying our invention not only produce the source of power itself but to a great extent also provide the torque converter to be replaced because the output at different r.p.m. of the engine described above is quite different from that of combustion engines. Furthermore, the torque of the engine can be used within a much wider range than in the case of a combustion engine. All these features contribute to the assumption that the costs of a power plant based on the new engine will be considerably lower than those of a corresponding combustion engine with gear mechanisms or torque converters.

It will be understood that the steam exhausted from the engine can be discharged into the ambient air. When this cannot be done conveniently, a closed circulation path for the working medium can be employed which includes a condenser from which liquid working medium returns to the steam generator. At the same time a heat exchanger can be provided in which steam exhausted from the engine flows in heat exchange relation with water supplied to the steam generator.

We claim:

1. In combination,

a. a reciprocating engine having a cylinder and a cylinder head therefor, said cylinder defining a working space,

a piston for said cylinder which is movable forward and backward therein in a path of movement,

. said cylinder head defining an outer space which is outside the working space of said cylinder and adapted to receive a compressible working medium under pressure,

d. an apertured wall between the outer space and the working space, said wall having an opening,

. valve means movable to and from a closed position at the opening,

said valve means including a valve body,

. means for controlling said valve body responsive to the pressure of the working medium,

. means for regulating the influence of the working medium on the movement of said valve body responsive to the position of said piston in its path of movement in said cylinder,

. spring means for biasing said valve body toward the opening in said apertured wall to move said valve means to its closed position,

I said cylinder head having a space in which said spring means is disposed,

k. means providing a passageway between the working space of said cylinder and said spring means space, said passageway at one end having an opening at the inside wall of said cylinder,

. the pressure of the working medium in said spring means space on said valve body balancing the pressure in the outer space on said valve body in a direction opposite to the biasing action of said spring means whereby said spring means becomes effective to move said valve means to its closed position responsive to movement of said piston from said cylinder head past the opening of said passageway at the inside wall of said cylinder to a position at which the last-mentioned opening is in communication with the working space of said cylinder,

m. means providing a first chamber exteriorly of said valve body which is defined in part by the latter,

n. means providing one passageway between said outer space and said first chamber,

0. first valve structure for controlling flow of working medium in said one passageway from said outer space to said first chamber, and

p. the part of said valve body defining said first chamber having a surface for imparting movement to said valve means in a direction from said apertured wall when said first valve structure is open and working medium flows from said outer space to said first chamber.

2. A reciprocating engine as set forth in claim 1 which includes means providing a second low-pressure chamber, such as a condenser, for example, means providing another passageway between said first and second chambers, and second valve structure in said other passageway between said first and second chambers, said second valve structure being closed when said first valve structure is open.

3. A reciprocating engine as set forth in claim 2 in which said engine has a single cylinder, and means for opening said first valve structure to start said engine when said piston is in a proper position to effect such starting.

4. A reciprocating engine as set forth in claim 3 which includes means coupling said first and second valve structures in such manner that said first valve structure is closed when said second valve structure is open and vice versa, and spring means biasing said coupling means to urge said first valve structure to its closed position and said second valve structure to its open position.

5. A reciprocating engine as set forth in claim 1 in which said engine has a single cylinder, and means for opening said first valve structure to start said engine when said piston is in a proper position to effect such starting, said means being dependent on the position of the piston and hence of the crankshaft so that the valve for inlet pressure cannot be opened until the piston is in a position suitable for starting the engine.

6. A reciprocating engine as set forth in claim 1 in which said engine has at least two cylinders and means to start said engine by opening said first valve structure in the passageway to said first chamber in the cylinder head of the cylinder in which the piston is in the best position for start.

7. In combination,

a. a reciprocating steam engine having a cylinder and a cylinder head therefor, said cylinder defining a working space,

b. a piston for said cylinder which is movable forward and backward therein in a path of movement,

c. said cylinder head defining an outer space which is outside the working space of said cylinder and sealed from the atmosphere and adapted to receive steam under pressure,

e. valve means movable to and from a closed position at the opening,

f. said valve means including a valve body,

g. means for controlling said valve body responsive to the pressure of the steam,

h. means for regulating the influence of the steam on the movement of said valve body responsive to the position of said piston in its path of movement in said cylinder,

i. spring means for biasing said valve body toward the opening in said apertured wall to move said valve means to its closed position,

j. said cylinder head having a space in which said spring means is disposed,

k. means providing a passageway between the working space of said cylinder and said spring means space, said passageway at one end having an opening at the inside wall of said cylinder, and

l. the pressure of the steam in said spring means space on said valve body balancing the pressure in the outer space on said valve body in a direction opposite to the biasing action of said spring means whereby said spring means becomes effective to move said valve means to its closed position responsive to movement of said piston from said cylinder head past the opening of said passageway at the inside wall of said cylinder to a position at which the lastmentioned opening is in communication with the working space of said cylinder.

8. The combination set forth in claim 7 in which said valve body has a first surface in said spring means space which, when acted upon by the steam in the last-mentioned space, tends to move said valve means in a first direction toward the opening in said apertured wall, said valve body having a second surface which, when acted upon by the steam in said outer space, tends to move said valve means in a second opposite direction from the opening in said apertured wall, the first surface having an area greater than the second surface so that the biasing action of said spring means and the product of the pressure of the steam and the difference in area between the first and second surfaces becomes effective to move said valve body toward the opening in said apertured wall and move said valve means to its closed position.

9. The combination set forth in claim 7 in which said means providing said passageway between the working space of said cylinder and said spring means space includes a first portion having a first opening at the inside wall of said cylinder and at least one additional portion in parallel with said first portion also having an opening 'at the inside wall of said cylinder, said openings at the inside wall of said cylinder being at different distances from said apertured wall having the opening, and selecting means for rendering any one of said portions active and the remainder inactive to control the speed of the engine.

10. A reciprocating steam engine as set forth in claim 7 in which said cylinder has a clearance volume of such size that, when said piston is moving toward said apertured wall during its backward movement, the compression developed therein will be capable of moving said valve means from its closed position against the biasing action of said spring means to equalize the pressure of the steam in said cylinder and in said outer space, whereupon the steam acting on said valve body functions to move said valve means to its wide open position and keep it in such position against the biasing action of said spring means.

Claims

1. In combination, a. a reciprocating engine having a cylinder and a cylinder head therefor, said cylinder defining a working space, b. a piston for said cylinder which is movable forward and backward therein in a path of movement, c. said cylinder head defining an outer space which is outside the working space of said cylinder and adapted to receive a compressible working medium under pressure, d. an apertured wall between the outer space and the working space, said wall having an opening, e. valve means movable to and from a closed position at the opening, f. said valve means including a valve body, g. means for controlling said valve body responsive to the pressure of the working medium, h. means for regulating the influence of the working medium on the movement of said valve body responsive to the position of said piston in its path of movement in said cylinder, i. spring means for biasing said valve body toward the opening in said apertured wall to move said valve means to its closed position, j. said cylinder head having a space in which said spring means is disposed, k. means providing a passageway between the working space of said cylinder and said spring means space, said passageway at one end having an opening at the inside wall of said cylinder, l. the pressure of the working medium in said spring means space on said valve body balancing the pressure in the outer space on said valve body in a direction opposite to the biasing action of said spring means whereby said spring means becomes effective to move said valve means to its closed position responsive to movement of said piston from said cylinder head past the opening of said passageway at the inside wall of said cylinder to a position at which the last-mentioned opening is in communication with the working space of said cylinder, m. means providing a first chamber exteriorly of said valve body which is defined in part by the latter, n. means providing one passageway between said outer space and said first chamber, o. first valve structure for controlling flow of working medium in said one passageway from said outer space to said first chamber, and p. the part of said valve body defining said first chamber having a surface for imparting movement to said valve means in a direction from said apertured wall when said first valve structure is open and working medium flows from said outer space to said first chamber.

7. In combination, a. a reciprocating steam engine having a cylinder and a cylinder head therefor, said cylinder defining a working space, b. a piston for said cylinder which is movable forward and backward therein in a path of movement, c. said cylinder head defining an outer space which is outside the working space of said cylinder and sealed from the atmosphere and adapted to receive steam under pressure, d. an apertured wall between the outer space and the working space, said wall having an opening, e. valve means movable to and from a closed position at the opening, f. said valve means including a valve body, g. means for controlling said valve body responsive to the pressure of the steam, h. means for regulating the influence of the steam on the movement of said valve body responsive to the position of said piston in its path of movement in said cylinder, i. spring means for biasing said valve body toward the opening in said apertured wall to move said valve means to its closed position, j. said cylinder head having a space in which said spring means is disposed, k. means providing a passageway between the working space of said cylinder and said spring means space, said passageway at one end having an opening at the inside wall of said cylinder, and l. the pressure of the steam in said spring means space on said valve body balancing the pressure in the outer space on said valve body in a direction opposite to the biasing action of said spring means whereby said spring means becomes effective to move said valve means to its closed position responsive to movement of said piston from said cylinder head past the opening of said passageway at the inside wall of said cylinder to a position at which the last-mentioned opening is in communication with the working space of said cylinder.

9. The combination set forth in claim 7 in which said means providing said passageway between the working space of said cylinder and said spring means space includes a first portion having a first opening at the inside wall of said cylinder and at least one additional portion in parallel with said first portion also having an opening at the inside wall of said cylinder, said openings at the inside wall of said cylinder being at different distances from said apertured wall having the opening, and selecting means for rendering any one of said portions active and thE remainder inactive to control the speed of the engine.