US3801236A - Engine - Google Patents

Abstract

A rotary fluid engine powered by externally pressurized working fluid including a rotor and a plurality of swinging arms positioned to engage with and impart a torque force to the rotor when the arms are driven sequentially inward by the selective admission of charges of externally pressurized working fluid. A first segment on the rotor surface engages the free end of each arm as the arm is driven inwardly and a second segment on the rotor surface operates to return the arm outwardly after the power impulse is completed. Valving and conduit means are provided to control the direction of the working fluid to the arms and exhaust means are provided to exhaust spent working fluid from the engine. In one embodiment, the valving and conduit means are adapted to direct charges of externally pressurized working fluid sequentially against said arms so that the engine operates as a simple engine. In a second embodiment, the valving and conduit means are adapted to direct charges of externally pressurized working fluid first against one of said arms at a high pressure and secondly against another arm at a relatively lower pressure so that said engine operates as a compound engine. In a third embodiment, transfer valve means are provided which permit said engine to be switchable between said simple and compound modes of operation. The rotor surface may include a plurality of said first and second segments so that each arm will transmit a corresponding plurality of power impulses to the rotor for each complete rotor revolution.

Description

United States Patent [1 1 Hinckley ENGINE [75] Inventor: John N. Hinckley, Beloit, Wis.

[73] Assignee: Beloit College, Beliot, Wis. 22 Filed: July 24, 1972 21 Appl. No.: 274,740

Related US. Application Data [60] Division of Ser. No. 860,684, Sept. 24, 1969, Pat. No. 3,684,413, which is a continuation-in-part of Ser. No. 812,656, April 2, 1969, abandoned.

Primary ExaminerCarlton R. Croyle Assistant Examiner-John J. Vrablik Attorney, Agent, or Firml-lume, Clement, Brinks, William, Olds & Cook, Ltd.

[57] ABSTRACT A rotary fluid engine powered by externally pressur- [451 Apr. 2, 1974 ized working fluid including a rotor and a plurality of swinging arms positioned to engage with and impart a torque force to the rotor when the arms are driven sequentially inward by the selective admission of charges of externally pressurized working fluid. A first segment on the rotor surface engages the free end of each arm as the arm is driven inwardly and a second segment on the rotor surface operates to return the arm outwardly after the power impulse is completed. Valving and conduit means are provided to control the direction of the working fluid to the arms and exhaust means are provided to exhaust spent working fluid from the engine. In one embodiment, the valving and conduit means are adapted to direct charges of externally pressurized working fluid sequentially against said arms so that the engine operates as a simple engine. In a second embodiment, the valving and conduit means are adapted to direct charges of externally pressurized working fluid first against one of said arms at a high pressure and secondly against another arm at a relatively lower pressure so that said engine operates as a compound engine. ln a third embodiment, transfer valve means are provided which permit said engine to be switchable between said simple and compound modes of operation. The rotor surface may include a plurality of said first and second segments so that each arm will transmit a corresponding plurality of power impulses to the rotor for each complete rotor revolution.

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sum 11 or 12 ENGINE This application is a division of my application Ser. No. 860,684, filed Sept. 24, 1969, now U.S. Pat. No. 3,684,413, which in turn is a continuation-in-part of my application Ser. No. 812,656, filed Apr. 2, 1969, entitled ENGINE, now abandoned, and assigned to the same assignee as the present invention.

The present invention relates to an improved prime mover and more particularly relates to an improved rotary engine which is powered by externally pressurized working fluid and is capable of replacing or supplementing conventional reciprocating piston internal combustion engines.

As well-known to those skilled in the art, the internal combustion engine in current use has many inherent disadvantages which have caused considerable concern about the continued use of that type of an engine as the dominent prime mover. For instance, two principal disadvantages of internal combustion reciprocating piston engines are low thermal efficiency and poor pollutant emission characteristics. These disadvantages result mainly from the inability of the engine to utilize the fuel effectively or to complete the combustion of the fuel within the expansion chamber of the engine before exhausting the spent fuel to the atmosphere. Another disadvantage of reciprocating piston engines in currentv use is inherently low overall mechanical efficiency. It is well-known, for instance, that the overall efficiency of piston engines is suppressed to approximately 25 percent by such factors as the inability of the pistons to produce power for about the first 30 and last 40 of each stroke, and the need for power-absorbing static and dynamic counterbalancing, and parasitic auxiliary systems.

Many attempts have been made to improve upon the thermal characteristics of reciprocating piston engines. These attempts have included such efforts as 'major engine redesign to increase the fuel combustion during expansion, and suppression of exhaust emissions with parasitic equipment, such as regenerators and the like.

Despite the success of some of these efforts, most reciprocating engine designs continue to require expensive fuels and continue to have unacceptably high pol? -lution characteristics. Efforts to improve the characteristics of reciprocating engines have also led to complicated designs which are expensive to manufacture, operate and maintain, and which continue to have an unsatisfactorily low mechanical efficiency.

The present invention overcomes the abovementioned problems of reciprocating piston engines by providing a rotary engine which is powered by externally pressurized working fluid and is capable of operating with substantially improved mechanical and thermal efficiencies and substantially improved antipollution characteristics. The rotary engine of the present invention also has a high horsepower-to-weight ratio and can produce high torque with a smooth and continuous flow of power to the output shaft. The structural and functional characteristics of this improved rotary engine also permit great flexibility of operation thereby allowing the engine to be adapted for a variety of applications.

The rotary engine is adapted for use in a power system having a continuous source of working fluid and means for pressurizing the working fluid outside of the engine. The system also includes means for feeding charges of such externally pressurized working fluid into the engine so that the pressurized fluid expands in the engine and creates a torque force which drives the engine output shaft. The externally pressurized working fluid may comprise a compressed gas such as compressed carbon dioxide, in which case the power system is provided with means for maintaining the gas under pressure. Alternatively, the extemally pressurized working fluid may be a pressurized vapor such as superheated steam, and the power system provided with an external heat source, such as a boiler, for creating the pressurized vapor. Similarly, the power system including the engine may use an open fluid cycle wherein the working fluid is exhausted to the atmosphere after expansion in the engine, or may use a closed fluid cycle which recirculates the working fluid through the system.

Exemplary Embodiments Additional objects and features of the present invention will become apparent from the following'description of several exemplary embodiments. In the illustrated embodiments, the engine is adapted as a Rankine cycle engine having a closed fluid system wherein energy is added to the pressurized working fluid by the application of external heat. Superheated steam is the preferred working fluid for the illustrated system, but it will be appreciated by those skilled in the art that alternative working fluids such as mercury 'or organic compounds reduced to vapor can be utilized with equal effectiveness in such a vapor cycle system. In some of the illustrated embodiments, the engine rotor is provided with a single lobe, and the engine is adapted so that each arm transmits one power impulse to the rotor for each rotor revolution. In other illustrated embodiments, the engine rotor is provided with double opposed lobes, and the engine is adapted so that each arm transmits two power impulses to the rotor for each rotor revolution.

The standard components of the Rankine cycle system, such as the fluid reservoir, the vapor generator for creating the externally'pressurized working fluid, the condenser, valves, pumps and heaters, have been excluded from the disclosure for purposes of simplicity. The operation of such components to create the pressurized working fluid, such as by converting water vapor to superheated steam by the application of exter- 'the engine are well-known and therefore need not be described in detail.

In the drawings:

FIG. 1 is a partial cross-sectional view of a simple external combustion engine in accordance with this invention embodying a single-lobe rotor, as viewed along the line 11 in FIG. 2;

FIG. 2 is a partial cross-sectional view of the simple external combustion engine illustrated in FIG. 1, as viewed from a plane parallel to the output shaft;

FIG. 3 is a partial cross-sectional view of a compound external combustion engine in accordance with this invention embodying a single-lobe rotor, as viewed along the line 3-3 in FIG. 4;

FIG. 4 is a partial cross-sectional view of the compound external combustion engine illustrated in FIG. 3 as viewed from a plane parallel to the output shaft;

FIG. 5 is a schematic end view of a valve housing .for the compound engine which is adaptedto transfer the pressurized working fluid from one engine expansion chamber to another expansion chamber;

FIG. 6 is a schematic view illustrating the flow of working fluid through the compound engine;

FIG.'7 is a schematic end view of a valve housing adapted for use with the compound engine illustrated in FIGS. 3 and 4 which modifies the engine to permit selective switching between the simple and compound modes of operation;

FIG. 8 is a schematic view illustrating the switchable engine operating as a simple external combustion en-' gine, and further illustrating the valving and manifold system which permits the engine to be switched between a compound and simple mode of operation;

FIG. 9 is a partial cross-sectional end view of an engine assembly formed from dual engine units which incorporate a double-lobe rotor and which are crosscoupled and offset to form a balanced compound external combustion engine;

FIG. 10 is a cross-sectional side view of the compound external combustion engine assembly illustrated in FIG. 9, as viewed along the line l in FIG. 9;

FIG. 1 1 is a cross-sectional end view of the engine assembly illustrated in FIGS. 9 and 10 schematically 7 showing the valving and manifold systems which adapt the engine assembly for a compound mode of operation;

FIG. 12 is a cross-sectional end view of the engine illustrated in FIGS. 9 and 10 schematically showingthe valving and manifold systems which adapt the engine for a simple mode of operation;

FIG. 13 is a partial cross-sectional end view of another embodiment of the engine in accordance with this invention incorporating a double-lobe rotor and six swinging arms which cooperate to form a balanced simple external combustion engine unit;

.FIG. "l4.is a cross-sectional side view of the simple engine illustrated in FIG. 13, as viewed along'the line 14-14 in FIG. 13; 4

FIGS. ISA-D are removed partial sectional views of a suitable adjustable valve means for selectively controlling the admission and cutoff of the working fluid in the engine illustrated in FIGSL 13 and 14;

FIG. 16 is a partial cross-sectional end view of still another embodiment of the engine incorporating a double-lobe rotor and six swinging abutment arms which is adapted to be switchable between simple and compound modes of operation;

FIGQ17 is a cross-sectional side view of the switchable engine as viewed along the line 17-17 in FIG. 16;

FIG. 18 is a removed end view of the fluid transfer plate incorporated in the switchable engine illustrated in FIGS. 16 and 17;

FIG. 19 is an end view of the transfer plate shown in FIG. '18 schematically illustrating the relationship between the transfer plate and the cut-off valves of the engine assembly.

Single-Lobe Rotor FIGS. 1 and 2 illustrate an external combustion engine embodiment of the present invention having a single-lobe rotor which is adapted for a simple mode of operation, that is there is no compounding of expansion of the pressurized working fluid before the fluid is exhausted from the engine. This simple engine is designed to utilize single charges of pressurized working fluid expanded in the engine for prolonged periods of time, such as throughout about 75 or 80 percent of the expansion period. As a result of this mode of operation, the engine has a high-torque output and is suitable for low-speed high-torque applications.

Referring to FIGS. 1 and 2 in more detail, the simple external combustion engine is generally indicated by the reference numeral 10. The engine 10 includes a rotor housing 20 containing three pivoted swinging abutment arms A, 40B and 40C and a single-lobe power rotor 50. The arms 40A-C are pivotally mounted on pins 4lA-C (FIG. I) and the rotor is pivotally mounted on a central drive shaft 30. Such pivotal connections for the arms 40A-C and rotor 50 are accomplished by keys or splines and are free-floating connections which permit the arms and rotor to float laterally and maintain a position of equilibrium within the housing 20 during the operation of the engine.

As indicated in'FIG. l, the rotor housing 20 and the interior surfaces of the arms 40A-C cooperate to define a generally cylindrical chamber within which the rotor SO'can rotate. Generally, during the operation of the engine a pressurized working fluid such as high pressure superheated steam is directed into the interior of the rotor housing 20 in a manner which forces the arms 40A-C sequentially inwardly against the surface of the rotor 50. The expanding working fluid works against the arms 40A-C and the exposedsurface of the rotor 50 to thereby impart a rotational driving force to the rotor, and the rotor in turn transmits an output torque to the drive shaft 30.

As seen in FIG. 2, one end of the rotor housing 20 is closed by a flywheel housing 60 and the other end is I closed by a valve housing '70. The housings 60 and 70 include centrally positioned main bearings 6l and 71, respectively, which support the drive shaft 30. The housings 60 and 70 also inciude machined end plates 62and 72, respectively, which seal the adjacent ends of the rotor housing 20. Suitable head bolts and gasketing (not shown) are provided to assure thatthe plates 62 and 72 seal the rotor housing 20 effectively. The

, plates 62 and 72 also pivotally support the pivotpins 4lA-C (FIG. 1) about which the arms 40A-C pivot for operating the engine accessories. A lubricator pump 66, driven by the pinion 65, is connected to a sequentially-metered lubrication system (not shown) which meters the necessary amount of lubricating oil to each surface such as the bearings 61 and 71 requiring lubrication. Inspection plates 67 and 68 are also provided on the flywheel housing 60 to permit access to the interior of the housing for inspection and repair.

As shown in FIG. 2, the rotor 50 and arms 40A-C of the engine in accordance with this invention are closely machined to have approximately the same width as the rotor housing 20. This design provides for a large surface area on the rotor 50 and arms 40A-C for contact with the working fluid during the operation of the engine. Moreover, by this arrangement the rotor and arms are positioned in the housing and spaced from the plates 62 and 72 only by a close tolerance. Sealing means thus can be provided between the sides of the arms 40A-C and rotor 50 and the plates 72 and 62 to prevent leakage of any working fluid past the rotor or arms.

In the preferred embodiment of the invention, labyrinth sealing is used to seal the sides of the rotor 50 and arms 40A-C with respect to the endplates 62 and 72. Such labyrinth sealing eliminates the need for lubricating moving parts such as piston rings or seals and is accomplished by providing a series of short labyrinth grooves 52 on the sides of the rotor 50 and similar grooves 42 on the sides of each of the arms 40A- C. The grooves 42 and 52 are arranged to follow the profile of the associated arms or rotor so that each groove acts as a check valve to stop the flow of working fluid past the arms or rotor in the clearance adjacent the plates 62 and 72. The short labyrinth grooves 42 and 52 also prevent the working fluid from traveling along the full length of the rotor or arms. The above-described-freefloating connections for the arms 40A-C and rotor 50 assist the scaling function of the labyrinth grooves 42 and 52 by allowing the arms and rotor to be selfcentering within the housing 20. The effectiveness of the labyrinth grooves 42 and 52 is further assisted by designing the rotor 50, arms 40A-C and housing 20 so as to have substantially equal coefficients of expansion. The clearance between the plates 62 and 72 and the rotor and arms therefore will be substantially constant of which is associated with each of the arms 40A-C.

Each admission chest 74A -'C is connected to a vapor generator (not shown) or another suitable source of high pressure fluid by means of intake pipes 75. As

shown in FIG. 2, the chests 74A-C also are in fluid communication with an expandable chamber defined by the rotor housing 20 and the associated arm 40A-C through intake manifolds 76 provided in the valve housing 70 and through aligned intake chambers 22 provided in the rotor housing 20. The intake chambers 22 are spaced within the housing 20 (FIG. 1) so that the pressurized working fluid enters the rotor chamber at a location closely adjacent the free end of the associated arms 40A-C. By this arrangement, the entering charge of fluid initially contacts the associated arm at a point of great leverage and is capable of forcefully swinging the arm inwardly against the rotor 50. As seen in FIG. 1, the free end of the arms 40A-C seal the associated intake chamber 22 closed when the arm is in th outermost position.

The valve housing 70 also contains a valve mechanism for controlling the timing and rate at which the pressurized working fluid is admitted into the chests 74A-C. To accomplish such timing and metering, each of .the chests 74A-C is separated from the associated intake manifold 76 by a poppet valve 77. The stroke of regardless of the engine load or operating temperature.

As illustrated in FIG. 1, the free end of each of the arms A-C includes'a bevelled portion 43 which allows the associated arm to engage with the rotor 50 along a flat and highly machined contact surface. This substantial contact surface on the arms 40A-C is held against the rotor 50 by the force of the expanding working fluid and is sufficient to prevent any substantial leakage between the arms and rotor. The bevelled portion 43 also allows the rotor and arms to withstand a high loading force by distributing the force of the expanding working fluid over a large area of contact on the arms and rotor.

Each arm 40A-C has a projection 46 on its inner surface which defines the point closest to the associated pivot pin 41AC at which the rotor will engage with the arm. Such an arrangement assures that the forces of the rotor 50 will act on the arms 40A-C at a point of substantial leverage. A relief 47 is provided on each arm 40A-C to allow clearance for the rise 57 of the rotor to pass by the arms. Sealing strips 44 are provided to seal the arms 40A-C with respect to the rotor housing 20 adjacent the pivoted end of the arms, as shown in FIG. 1. The strips 44 thereby separate the expansion and exhaust phases of the working fluid during the operation of the engine.'

The engine 10 in accordance with this invention also is provided with a valving mechanism which admits the charges of pressurized working fluid into the rotor housing 20 in the proper sequence. In the illustrated embodiment, for instance, the pressurized working fluid is admitted in a pattern which swings the arms 40A, 40B and 40C inward sequentially against the rotor 50, and drives the rotor clockwise in FIG. 1. To achieve such control of the working fluid, the valve housing 70 contains fluid admission chests 74A-C, one

each poppet valve 77 is controlled by cams 78 provided on the drive shaft 30. A conventional gearing mechanism 79, such as the Stephenson mechanism illustrated schematically in FIG. 2, connects the valves 77 to the.

cams 78 and permits the closing stroke of the valves 77 to be adjusted to vary the rate or quantity of working fluid supplied to the engine. As well-known to those skilled in the art, such a variable cutoff mechanism can be operated either manually or automatically to vary the operating chracteristics or the performance of the engine 10. A cover plate 80 closes the valve housing 70 and protects the above described valve mechanism from damage.

The engine 10 also includes an exhaust system for discharging the spent working fluid from the expandable chamber defined by the rotor housing 20 and each arm 40A-C. In this regard, the valve housing 70 is provided with a plurality of exhaust manifolds 92 which are spaced uniformly about the housing to receive the spent working fluid from the three segments of the'engine 10. In addition, the end plates 62 and 72 of the housings 60 and 70 are provided with uniformly spaced exhaust ports A-C. As indicated in FIG. I, an exhaust port 90 is positioned near the pivoted end of each of the adjacent arms 40A-C. Each port 90 is in fluid communication with the adjacent exhaust manifold 92 and can thereby operate to discharge the working fluid from the expandable chamber associated with the preceding arm. The fluid is thereby exhausted into a suitable condenser or the like, from which the fluid is fed to a vapor generator and re-pressurized forrecirculation through the engine.

The ports 90A-C are designed to be sufficiently large to permit rapid exhaustion of the spent working fluid with a minimum loss of energy. Further, the ports 90A-C are positioned to permit the power impulses on the rotor 50 to overlap, so that the operation of the engine 10 is smooth andthe application of torque to the rotor 50 is continuous.

To eliminate the need for auxiliary exhaust valve mechanisms, the engine 10 includes valving portions 40AC, to control the opening and closing of the associated exhaust ports 90A-C. As illustrated in FIG. 1, the valving portions 45A-C extend beyond the arm pivot pins 41A-C to cover the adjacent exhaust port 90A-C when the associated arm is in its outermost position (See arm 403, FIG. 1). The valving portions 4SA-C swing away to open the ports 90A-C when the associated arm 40AC swings into its innermost position (See arm 40C, FIG. 1). The valving portions 45A-C are designed so that the opening and closing of the exhaust ports 90A-C are coordinated with the positioning of the arms 40A-C and the rotor 50 during the operation of the engine 10. I

The rotor housing 20 has recesses 25 to receive the valving portions 45A-C as the arms 40A-C move inwardly toward the rotor 50. The sealing strips 44 frictionally engage with the associated arm and prevent the pressurized working fluid from becoming trapped within the recess 25. The recesses 25 preferably are vented to theatmosphere by suitable means (not shown) so that any working fluid which may enter the recesses is exhausted without inhibiting the action of the associated arm.

1n the preferred embodiment of this invention, the rotor 50 is adapted to control the sequence of movement of the arms 40AC to overlap the power impulses transmitted to the rotor so that the flow of power to the rotor 50 is smooth and continuous. The rotor 50 also controls the inward and outward movement of the arms so that the swinging motion of each arm closely approximates a simple harmonic motion. Such arm movement minimizes the amount of energy absorbed by inertia losses resulting from the rapid reversal of the arms.

The surface of the-rotor S is designed to engage with the bevelled portions 43 of the arms 40A-C to receive a power impulse from the arms and to control the sequential movement of the arms during the operation of the engine. To accomplish these functions, the rotor 50 includes a nose or high point 53 positioned to engage with the adjacent arm 40A-C and maintain the arm in its outermost position for a selected time period (See arm 408, FIG. 1). Further, the surface of the rotor defines a fall segment 54 which isengaged by the arms 40A+C as the arms are driven inwardly by the force of the working fluid (See arm 40A, FlG. l). The fall segment 54 has a configuration which causes the arms 40A-C- to move inwardly with approximately simple harmonic motion. The arm fall segment 54 terminates with asloping .portion 55 which decelerates the inwardly moving arm and prepares the arm for a reversal of direction. Y

The sloping portion 55 leads the inwardly moving arm 40A-C to a low dwell segment 56 on the surface of the rotor 50. The low dwell segment 56 is concentric to the axis of rotation of the rotor 50 and extends along the rotor surface for a selected number of degrees. The dwell segment 56 thereby stops the inward movement of the arms 40A-C and defines the limit for inward arm travel.

Since the three arms 40A-C in the illustrated engine are spaced 120 apart, the cycle of operation for the arms will be 120 out-of-phase, and the movement of adjacent arms will be separated by 120 of rotor rotation. Thus, each of the arms 40A-C will complete its inward movement, and traverse the fall segment 54 from the high point 53 to the low dwell segment 56, as

- the rotor 50 rotates through 120. However, in the preferred arrangement the fall segment 54 is designed to complete the inward movement of the arms 40A-C as the rotor rotates for less than 120, for instance This arrangement allows the arms to decelerate smoothly and assures that the stroke of one arm, such as arm 40A, is completed before the exhaust cycle is started by movement of the adjacent arm.

The movement of the adjacent arm (arm 403) will start after of rotation of the rotor 50, but the valving portion 45 of the arm and the associated exhaust port 90 are arranged so that exhaust does not start until that arm moves through a small arc, such as l020. This design permits an overlapping of the power impulses, to obtain optimum torque on the rotor 50., by preventing the exhaust ports 90 from opening prematurely.

The overlapping of the power impulses on the rotor 50 is assisted by designing the low dwell segment 56 of the rotor 50 with an arc of 10 to 20 so that the arms 40A-C contact the segment for a short time after the rotor has rotated beyond 120. The dwell segment 56 thereby precludes outwardmovement of the engaged arm 40 until after the power strokes of the adjacent arms (e.g., 40A and 4013) have overlapped and the associated exhaust port 90 has opened. This arrangement of the dwell segment 56 also allows the working fluid to expand fully against the inwardly moving arm 40 and roto 50 before the arm starts to move outward and force the fluid into the exhaust system.

The next segment of the rotor 50 which engages with the arms 40AC is a rise segment 57 which is designed to force the engaged arm outwardly from its innermost position (See arm 40C, FIG. 1) toward its outermost position (See arm 408, FIG. 1) with simple harmonic motion. The rise segment 58 preferably is designed to drive the arms 40A-C outwardly as the rotor 50 rotates through approximately ninety additional degrees.

The remaining surface of the rotor 50 between the rise segment 57 and the high point 53 comprises a high dwell segment 58. T his segment 58 is concentric with the axis of the rotation of the rotor 50, and is designed to maintain the adjacent arm 40 in its outermost position (See arm 40B) through approximately of rotation of the rotor 50. The rotor 50 then has rotated 360 with respect to the arms 40, and is in a position'to repeat its operating cycle. The above-described rotor segments thereby provide the rotor 50 with a single lobe, having a high point 53 which allows each arm 40A-C to complete. its cycle of movement once for eachrevolution of the rotor. By this arrangement, each arm 40A-C will transmit one power impulse to the rotor 50 per rotor revolution.

In operation, the swinging arms 40A-C transmit torque to the rotor 50 in proportion tothe force imposed upon the outward sides of the arms by the pressurized working fluid. The rotor 50 and arms 40A-C further act to seal the fluid expanding in one segment of the engine 10 from the fluid exhausting from another engine segment. This functional interrelationship between the arms 40 and the rotor 50 will be understood from a description of the operation of the engine through .one complete cycle. Since the engine 10 consists of three symmetrical segments, each including one of the arms 40A-C, the cycle could start with any one arm. Fur purposes of illustration, the operation of the engine will bedescribed with reference to a cycle initiated by admitting a charge of steam through the steam chest 74A to act upon the arm 40A.

To begin the engine operation, the valve gear mechanism 79 is adjusted, either manually or automatically, to introduce a charge of steam through the chest 74A at the desired rate. The mechanism 79 can be varied to cut off the steam charge after the rotor 50 rotates through a few degrees or after the maximum 120 of rotor rotation. As well-known by those skilled in the art, a longer cutoff time introduces a greater quantity of working fluid into the rotor chamber and increases the power output of the engine.

The valve mechanism 79 and the rotor 50 are timed so that the steam charge is admitted through the chest 74A and the associated channel 22 as the high point 53 of the rotor 50 passes the bevelled portion 43 on the free end of the arm 40A. The entering steam expands against the arm 40A and the rotor 50 and forcefully drives the arm 40A inwardly against the rotor. The expanding steam thereby imparts a torque force to the rotor 50, and drives the rotor and the shaft 30 (in a clockwise direction in FIG. 1). as seen in FIG. 1, the engagement of the rotor 50 with the arms 40A and 40B seals the resulting expandable steam chamber (the increased volume below arm 40A) from the remaining portion of the rotor chamber.

In the illustrated engine 10, the fall segment 54 on the rotor 50 allows the arm 40A to move inwardly as the rotor 50 rotates through approximately 110. The motion of the arm 40A is then decelerated by the rotor sloping portion 55. The inward motion of the arm 40A is finally stopped when the arm engages the low dwell segment 56. In this embodiment, the arm 40A remains engaged with the segment 56 and remains in its innermost position until the rotor 50 rotates an additional 20, or through a total are of 130.

Simultaneous with the above-described operations, the valve mechanism 79 operates to admit a second charge of superheated steam to the chest 74B and into the expandable chamber defined between the second arm 40B and the rotor housing 20. When the rotor 50 has traveled through 120 and thereby moved the rotor high point 53 past the bevelled portion 43 on the arm 408, the second charge of steam forces the arm 408 inwardly against the rotor. By this arrangement, a second power impulse begins against the rotor 50 at 120 of rotor rotation. Furthermore, the valving portion 458 on the arm 40B and the associated exhaust port 908 are designed so that the port 908 is not opened until the rotor 50 has moved beyond the free end of the arm 408. Thus, the first steam charge in the expandable chamber associated with the preceding arm 40A continues to expand and impart a torque to the rotor for this additional 10, and overlaps with the force of the second steam charge during that interval.

In the illustrated engine 10, the first arm 40A engages the rotor rise segment 57 afte 130 of rotor rotation. Continued rotation of the rotor through 90 drives the first arm 40A outwardly and permits the secondarm 40B to be forced inwardly. The outwardly moving arm 40A will thereby scavenge the first charge of steam and discharge the steam through the enlarging exhaust port 90B. Further rotation of the rotor 50 through the remaining 140 brings the high dwell segment 58 into engagement with the arm 40A. The arm 40A is thereby maintained in its outermost position while the cycle for the second arm 40B is being completed.

The same cycle of operation as described above for the arm 40A is followed by-the arm 40C. It will be readily understood, however, that the cycle for the third arm 40C follows the cycle of arm 405 by 120, and leads the cycle for arm 40A by the same amount.

To illustrate the high torque characteristics of the .simple engine 10 in accordance with this invention,

various engine operating parameters were fed into a computer which was programed to calculate the expected performance of an engine having a rotor chamber with a four inch width and a 7.5 inch internal diameter and having the single-lobe rotor shaped as generally shown in FIGS. 1 and 2. In one computer example, th incoming steam pressure was selected as 200 psi gauge pressure, and the steam cutoff was selected to occur in each segment of the engine after the rotor had traveled through 110. The steam was allowed to expand through 130 of rotor rotation to provide an overlap in the power impulses from the adjacent engine sections. The computerized data projected that under these conditions the steam pressure would drop to 179 psig after the steam is fully expanded through 130 and would then be exhausted. The computerized data also projected that the ,mean output torque for the engine was 7,421 inch pounds, with a resultant power output of 141 indicated horsepower at 1,200 rpm.

In another computerized example, the same simple engine was analyzed with 200 psig steam being admitted with the cutoff adjusted to 55 of rotation of the rotor. In this example, the steam was allowed to expand for an additional of rotor rotation and was finally exhausted at a pressure of 72 psig. The projected characteristics for this engine were a mean output torque of 5,815 inch pounds, with a resultant power output of 111 indicated horsepower at 1,200 rpm.

Similar computerized data also estabished that the power output of the engine in accordance with this invention is directly proportional to the rotor width and speed, and the pressure of the incoming charge of external working fluid. If any of these parameters are doubled, for instance, the resulting power output of the Compound Engine Single-Lobe Rotor FIGS. 3 through 6 illustrate an external combustion engine having a single-lobe rotor which is adapted for a compound mode of operation. In this compound engine each charge of pressurized working fluid is expanded twice in the engine. Since each expansion of the pressurized fluid transmits torque to the rotor, the compound engine has excellent fuel economy and can operate at high speeds for a sustained period. The compound expansion of each charge of working fluid also minimizes the condensation of the fluid within the engine when the engine is operated with. superheated steam.

Referring to FIGS. 3-6 in more detail, the compound external combustion engine includes many of the same components as the above-described simple engine 10. A rotor housing contains three pivoted swinging abutment arms A, 1408 and 140C, and a single-lobe power rotor 150. The arms l40A-C are pivotally mounted on pins 14lA-C, and the rotor 150 is mounted for rotation on a central drive shaft 130. The connections for the arms 140AC and rotor 150 comprise keys or splines or the like which permit the arms and rotor to float freely in the lateral direction, and be self-centering within the housing 120. The rotor housing 120 and the interior surfaces of the arms 140A-C define a generally cylindrical chamber within which the rotor 150 will rotate during the operation of the compound engine 100.

As illustrated in FIG. 4, one end of the rotor housing 120 is closed by a flywheel housing 160 and the other end is closed by a valve housing 170. The housings I60 and 170 include main bearings 161 and 1711, respectively, and define end plates 162 and 172 which seal the adjacent ends of the rotor housing. The end plates 162 and 172 support the pivot pins 141A-C (FIG. 3) about which the arms 140A-C rotate. The housing 160 contains a counterweighted flywheel 163 which is keyed to the drive shaft 130. Accessory drive gears and pinions 164 and 165 are also provided in the housing 160 for driving the engine accessories, such as a lubricating pump 166, in the well-known manner. The housing 160 also includes removable inspection plates 167 and 168.

As shown in FIG. 4, the rotor 150 and the arms 140A-C of the engine 100 have approximately the same width as the rotor housing 120. This arrangement provides a large surface area on the rotor and arms for contact with the working fluid, and spaces the rotor and arms within a very close tolerance to the end plates 162 and 172.. The rotor and arms thereby can be sealed with respect to the end plates 162 and 172 by a plurality of short labyrinth grooves 142 and 152. As described above, the labyrinth grooves 142 and 152 follow the profile of the associated arm or rotor, and act as check valves to stop the flow of working fluid past the rotor and arms. The arms 140A-C, rotor 150 and housing 120 are also designed to have substantially equal coefficients of expansion, so that the operation of toward the rotor 150. The sealing strips 144 prevent the working fluid from becoming trapped within the recesses 125. The recesses 125 also are vented to the atmosphere by suitable means (not shown).

As illustrated by the position of the arm 1408 in FIG. 3, the valving portions 145AC are arranged to close the adjacent exhaust portlA-C when the associated arm is in its outermost position. The valving portions 145A-C swing outwardly to open the adjacent port l90A-C when the associated arm swings into its innermost position. The operation of the exhaust ports l90A-C is controlled by the positioning of the arms 140A-C and the rotor 150.

Each of the arms 140A-C inthe compound engine also includes an outwardly projecting horn member 148. The horn members 148 are integral with the associated arm'and are designed to extend outwardly from the arm for a distance which exceeds the length of the inward arm stroke. The horns 148 are formed adjacent the free end of the arms, and terminate to define a substantially flat contact surface 149 on the outer end of each arm. As clearly illustrated in FIG. 3, each horn 148 has outwardly converging side edges which'give the horn an outwardly tapered or wedge-shaped configuration.

The rotor housing is formed with a plurality of horn recesses '128 to accommodate the projecting horns 148 The recesses 128 also have atapered shape which closely conforms to the shape of the horns 148 so that each recess will receive the adjacent horn when the associated arm A-C isin its outermost position (See arm 1408, FIG. 3). Further, as indicated by the arm 140C in FIG. 3, the horns 148 and recesses 128 are arcuate in shape so that the horns are in sealing engagement with the rotor housing 120 as the associated arm l40A-C moves inwardly toward the rotor 150. The tapered'shape of the horns 148, which provides the horns with a narrow width at their outer ends and a broader the labyrinth scaling is unaffected by engine load or operating temperature.

As illustrated in FIGS. 3 and 6, each of the arms l40A-'C- includes a bevelled portion 143 at its free end for contacting the surface of the rotor 150. Each arm also includes a projection 146 on its inner surface which prevents the rotor 150 from engaging with the arms at any point closer to the associated pivot pin l4lA-C. The rotor 150 will thereby engage each arm l40A-C at the high leverage section between the bevelled portion 143 and the projection 146. Each arm l40A-C also includes a relief 147 which provides clearance for the rise 157 of the rotor to pass by the arms. Further, sealing strips 144 are provided in the rotor housing 120 to engage with the adjacent arm 140A-C and seal the expansion chambers of the engine from each other and from the exhaust chambers.

The lower end of each arm 140AC also defines exhaust valving portions 1 45AC which move with the arms 140A-C and control the opening and closing of an associated exhaust port 190A-C. The exhaust ports 190A-C are cast in the face plates 162 and 172 of the gear housing and the valve housing and are connected to a fluid condenser or the like through exhaust manifolds 192. Recesses 125 receive the valving portions 145A-C as the associated arm moves inwardly width at their inner ends, prevents the'development of a partial vacuum in the horn recesses 128 which otherwise would inhibit the inward movement of the arms.

Since the extent of the horns 148 exceeds the length of the stroke of the arms l40A-C,the horns will remain in sealing engagement with the rotor housing 120 throughout the operation of the engine. By this arrangement, the space in the recess 128 behind-each arm 140A-C and the adjacent intake chamber 122 define a closed chamber which expands in volume as the associated arm l40A-C moves inwardly toward the rotor 150. In accordance with this invention, such chambers behind the arms l40A-C define high pressure chambers HP I-IP and HP respectively, which will receive a charge of working fluid at high pressure during operation of the compound engine 100.

In accordance with this invention, the engine 100 also is provided with low pressure chambers for receiving a charge of working fluid such as steam from each of the high pressure chambers I-IP,, to thereby compound the effect of the charge on the rotor 150. In the illustrated engine 100, the volume of the low pressure chambers LP is approximately one and one half to two and one half times the volume of the associated high pressure chambers HP However, this ratio may be varied over a broad range by varying the desing of the arms 140AC and the rotor 150.

To provide the low pressure chambers, the rotor housing 120 is cast to include uniformly spaced fluid channels 129. As shown in FIGS. 3 and 6, each channel 129 is positioned so that one end is in communication with the contact surface 149 on the adjacent arm 140AC, and the other end is in communication with an intake chamber 173 cast in the valve housing 170. By this arrangement, the working fluid expanding in the channel 129 will press against the adjacent surface 149 and urge the adjacent arm inwardly against the rotor 150. Further, as indicated by the arrangement of the arm 140A in FIGS. 3 and 6, the rotor and adjacent arms define an expanding, sealed chamber which is in communication with the adjacent channel 129. Thus, each segment of the compound engine 100 is provided with an expanding low pressure chamber, designated respectively as chambers LP ,-LP and LP which is sealed from the main portion of the rotor chamber by the adjacent arm l40A-C and the rotor 150, and sealed from the adjacent high pressure chamber HP by the adjacent arm horn 148. In addition, as seen in FIG. 3, each of the low pressure chambers LI,, is position adjacent one of the exhaust ports l90A-C. The charge of working fluid therefore can be exhausted through the adjacent port 190 after the expansion of the fluid in the low pressure chamber is completed.

The engine 100 also includes a manifold and valving system for controlling the admission of the pressurized working fluid into the high pressure chambers HP and for transferring the fluid, after expansion in the high pressure chambers, to the low pressure chambers Islwhere the fluid is expanded further before being exhausted from the engine. In this regard, the valve housing 170 includes a plurality of admission chests 174A-C which are arranged uniformly around the rotor 150. As shown in FIGS. 3 and 6, each chest 174A-C is in fluid communication with one of the high pressure chambers I-IP through a high pressure manifold 176 which is aligned with the intake chamber 122. Intake pipes 175 connect each manifold 176 with a vapor generator (not shown) or other suitable source of high pressure fluid.

Timing and metering of the incoming pressurized fluid is accomplished by separating the chests l74A-C from the associated intake manifold 176 by a poppet valve 177. The stroke from each valve 177 is controlled by cams 178 connected to the drive shaft 130 and by a Stephenson-type variable gearing mechanism 179. A cover plate 180 encloses the valve housing 170 to protect the above-described valving and manifold system from damage.

As illustrated in FIGS. 5 and 6, the valve housing 170 also includes transfer channels 194A, 1948 and 194C for transferring the working fluid from the high pressure chamber HP of one of the arms l4 0A-C to the low pressure chamber LP of the adjacent arm. More specifically, the transfer channel 194A extends across the housing 170 and connects the high pressure chamber I-IP directly to the low pressure chamber LP In a like manner, the channel 194B connects thehigh pressure chamber I-IP with the low pressure chamber LP and the channel 194C connects the high pressure chamber HP with the low pressure chamber LP,,. In the preferred embodiment of this invention, no valving is needed between the high pressure chambers HP and the associated transfer channel l94A-C. The initial charge of working fluid entering the high pressure chambers will fill the transfer channels. Then, the motion of the rotor 150 and arms l40A-C will control the transfer of the fluid charge through the channels from the high to the low pressure chambers, and the exhaust of the fluid from the low pressure chambers.

In the preferred embodiment wherein the compound engine is operated with steam or the like, the pressure chambers HP,, and LP the transfer channels l94A-C the rotor 150 and the arms A-C are designed so that the change in volume of the low pressure chambers LP is at the same rate as the change in vol- I ume of the associated high pressure chamber HP. As a result, substantially no work will be done on the fluid during the transfer and there will be substantially no energy loss during the transfer phase of the engine operation. In the alternative, if the thermodynamic characteristics of the working fluid require it, the fluid charge could be circulated through a suitable reheating system (not shown) or the like before the transfer through the channels l94A-C is completed.

The surface of the rotor controls the movement of the arms 140A-C so that each arm swings with approximately simple harmonic motion, and the inertia losses resulting from the rapid reversal of the arms is minimized. In the preferred embodiment, the rotor 150 also controls the sequence for the arms l40A-C so that the power impulses transmitted to the rotor are overlapping.

Accordingly, the rotor 150 includes a high point 153 which will engage with the adjacent arm l40A-C and maintain that arm in its outermost position for a selected period (See arm 140B, FIG/3). An arm fall segment 154 on the rotor 150 engages the arms l40A-C as the arms are driven inwardly by the force of the working fluid (See arm 140A, FIG. 3). The fall segment 154 is shaped to move the arms inwardly with approximately simple harmonic motion, and terminates with a sloping portion 155 which decelerates the inwardly moving arm at the end of the power stroke. The sloping portion 155 leads the inwardly moving arm l40A-C to a low dwell segment 156 on the rotor 150. The low dwell segment 156, which defines the inner limit for the arms 140AC, is concentric to the axis of rotation of the rotor 150 and extends along the rotor for a selected number of degrees.

In the illustrated compound engine 100, where the arms DNA-C are uniformly spaced by I20", the movement of adjacent arms will be 120 out-of-phase. Accordingly, each arm will complete its inward movement and traverse the fall segment 154 from the high point 153 to the low dwell segment 156, as the rotor 150 rotates through 120 degrees. In the preferred arrangement, the fall segment 154 is shaped to complete the inward stroke of each of the arms as the rotor rotates through an are slightly less than 120, such as l l0. Such an arrangement decelerates the arm smoothly and allows the arm to rest against the low dwell segment 156 before the direction of movement of the arm is reversed.

The next segment of the rotor 150 to engage with the arms l40A-C is an arm rise segment 157. The rise segment 157 sequentially engages each of the arms l40A-C and forces the arm outwardly from its innermost position (See arm 140C, FIG. 3), toward its outermost position (See arm 1408, FIG. 3) with approximately simple harmonic movement. In the illustrated engine 100, the rise segment 157 is designed to com-

Claims (19)

1. A rotary externally pressurized fluid engine comprising: a housing defining a generally cylindrical rotor space having parallel end walls; a rotor mounted on a shaft within said rotor space, said rotor having a substantial transverse surface and side portions spaced adjacent said end walls; a plurality of elongate arms positioned within conforming arm recesses provided around the inner periphery of said housing and spaced uniformly with respect to said rotor, each of said arms having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged within the associated arm recess and an inward position engaged with said rotor surface; a horn member provided on each of said arms intermediate said arm ends and projecting outwardly into the associated arm recess, each of said horn members being positioned to slide in the associated recess in sealing engagement with said housing as said arms move between said inward and outward positions; said rotor surface including a first segment sequentially engageable with the free ends of said arms as said rotor rotates to permit said arms to move inwardly from said outward position and a second segment sequentially engageable with the free ends of said arms as said rotor continues to rotate to return each arm to said outward position; a plurality of first expandable fluid chambers defined between said housing and said rotor adjacent the free ends of said arms; a plurality of second expandable fluid chambers defined by said arm recesses and the associated arms and sealed from said first chambers by said arm horn members; transfer channels connecting each second fluid chamber in flUid communication with a first fluid chamber associated with another arm; conduits connecting each first fluid chamber in fluid communication with the second chamber associated with the same arm; transfer valve means in fluid communication with said first chambers and selectively operable in one position to sequentially direct charges of said pressurized fluid into said chambers so that said charges operate simultaneously in the first and second chambers connected to said conduit means when said first segment of said rotor is positioned adjacent the free end of the associated arm, to operate said engine as a simple engine, said transfer valve means being further operable in a second position to sequentially direct charges of said pressurized working fluid into said second chambers for initial operation in said second chambers when said first segment of said rotor is positioned adjacent the free end of the associated arm so that the following movement of said arms changes the volumes of the first and second charges from said second chambers to said first chambers through said transfer channels, to permit said charges to operate further in said first chambers and thereby operate said engine as a compound engine; exhaust means in fluid communication with each first fluid chamber and arranged so that outward movement of said arms forces the fluid from said second chambers into the connected first chamber and forces the fluid from said first chambers through said exhaust means; and means sealing said side portions of said rotor and arms with respect to said housing end walls; whereby said transfer valve means permits said engine to be switchable between simple and compound modes of operation.

2. A rotary externally pressurized fluid engine comprising: a housing defining a pair of generally cylindrical rotor chambers having end walls; a pair of double-lobe rotors mounted on a common shaft so that one of said rotors is positioned in each of said rotor chambers, said rotors having substantial transverse surfaces and side portions spaced adjacent said end walls; four elongate arms uniformly spaced around the inner periphery of said housing in each of said rotor chambers within conforming arm recesses provided in said housing; each of said arms having side portions adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged within the adjacent arm recess and an inward position engaged with the adjacent rotor surface; a tapered horn member provided on each of said arms adjacent said free arm ends and projecting outwardly into the adjacent arm recess, each of said horn members having outwardly converging edges with one edge being positioned to slide in sealing engagement with said housing as said arms move between said inward and outward positions; said surface of each of said rotors including a pair of diametrically opposed first segments sequentially engageable with the free ends of an opposed pair of the associated arms to permit said engaged pair of arms to move inward and transmit a torque force to said rotor, each rotor further including a pair of diametrically opposed second segments sequentially engageable with the free ends of said opposed pair of arms to return said pair of arms to said outward position; a plurality of first expandable fluid chambers defined by said housing adjacent the free ends of each of said arms; a plurality of second expandable fluid chambers defined by said arm recesses and the associated arms and sealed from said first chambers by said arm horn members; transfer channels connecting each second chamber in one of said rotor chambers in fluid communication with the axially adjacent first chamber in the other rotor chamber; conduits connecting each first chamber in fluid communication with the second chamber associated with the same arm in the same rotor chamber; transfer valve means in fluid Communication with said first chambers and selectively operable in one position to sequentially direct charges of said pressurized fluid into said chambers so that said charges operate simultaneously against a pair of opposed arms in the first and second chambers connected by said conduits when said first rotor segments are positioned adjacent the free ends of the pair of arms, to operate said engine as a simple engine; said transfer valve means being further operable in a second position to sequentially direct charges of said pressurized working fluid into said second chambers for initial operation in said second chambers against a pair of opposed arms when said first rotor segments are positioned adjacent the free ends of the pair of arms so that the following movement of said pair of arms changes the volumes of the first and second chambers connected by said transfer channels and transfers said initial charges from said second chambers to said connected first chambers through said transfer channels, to permit said charges to operate further in said first chambers and thereby operate said engine as a compound engine; exhaust means in fluid communication with each first fluid chamber and arranged so that outward movement of said arms and continued rotation of said rotors forces the fluid from said second chambers into the connected first chambers and forces the fluid from said first chambers through said exhaust means; and means sealing said side portions of said rotors and arms with respect to said housing end walls; whereby the operation of said charges in one of said rotor chambers will overlap the operation of said charges in the other rotor chamber, and whereby said engine is switchable between simple and compound modes of operation.

3. A rotary externally pressurized fluid engine comprising: a housing defining a generally cylindrical rotor space having parallel end walls; a rotor mounted on a shaft within said rotor space, said rotor having a substantial transverse surface and side portions spaced adjacent said end walls; a plurality of elongate arms positioned within generally conforming arm recesses provided around the inner periphery of said housing and spaced uniformly with respect to said rotor, each of said arms having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged within the associated arm recess and an inward position engaged with said rotor surface; a tapered horn member provided on each of said arms adjacent said free arm ends and projecting outwardly into the associated arm recess, each of said horn members having outwardly converging side edges, with one edge being positioned to slide in sealing engagement with said housing as said arms move between said inward and outward positions; said rotor surface including a first segment sequentially engageable with the free ends of said arms as said rotor rotates to permit said arms to move inwardly from said outward position and a second segment sequentially engageable with the free ends of said arms as said rotor continues to rotate to return each arm to said outward position; a plurality of first expandable fluid chambers defined between said housing and said rotor adjacent the free ends of said arms; a plurality of second expandable fluid chambers defined by said arm recesses and the associated arms and sealed from said first chambers by said arm horn members; means to connect said second fluid chambers to a source of externally pressurized working fluid; valve means operable to sequentially direct charges of said working fluid under pressure into said second fluid chambers when said first segment of said rotor surface is positioned adjacent the free end of the associated arm so that said pressurized fluid will operate within said second chambers and forcefully urge the associated arm inwardly against said rotor and thereby impArt a torque to said rotor and shaft; transfer channel means connecting each of said second chambers to the first chambers associated with the adjacent following arm to transfer said charges from said second chambers into said connected chambers caused by the movement of the associated arms, to thereby compound the operation of said charges in said first chambers and operate said engine as a compound engine; exhaust means in fluid communication with each first fluid chamber and arranged so that outward movement of said arms and continued rotation of said rotor forces the fluid from said first chambers through said exhaust means; and means sealing said side portions of said rotor and arms with respect to said housing end walls.

4. A rotary engine in accordance with claim 1 wherein the change in volume of the connected first and second fluid chambers occurs at substantially the same rate so that the fluid charge is transferred from said second to said first chamber without performing substantial work on the fluid.

5. A rotary externally pressurized fluid engine comprising: a housing defining a generally cylindrical rotor space having parallel end walls; a rotor mounted on a shaft within said rotor space, said rotor having a substantial transverse surface and side portions spaced adjacent said end walls; a plurality of elongate arms positioned within generally conforming arm recesses provided around the inner periphery of said housing and spaced uniformly with respect to said rotor, each of said arms having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged within the associated arm recess and an inward position engaged with said rotor surface; a tapered horn member provided on each of said arms adjacent said free arm ends and projecting outwardly into the associated arm recess, each of said horn members having outwardly converging side edges, with one edge being positioned to slide in sealing engagement with said housing as said arms move between said inward and outward positions; said rotor surface including a first segment sequentially engageable with the free ends of said arms as said rotor rotates to permit said arms to move inwardly from said outward position and a second segment sequentially engageable with the free ends of said arms as said rotor continues to rotate each arm to said outward position; a plurality of first expandable fluid chambers defined between said housing and said rotor adjacent the free ends of said arms; a plurality of second expandable fluid chambers defined by said arm recesses and the associated arms and sealed from said first chambers by said arm horn members; means to connect said second fluid chambers to a source of externally pressurized working fluid; valve means operable to sequentially direct charges of said working fluid under pressure into said second fluid chambers when said first segment of said rotor surface is positioned adjacent the free end of the associated arm so that said pressurized fluid will operate within said second chambers and forcefully urge the associated arm inwardly against said rotor and thereby impart a torque to said rotor and shaft; transfer channel means connecting each of said second chambers to the first chambers associated with the adjacent following arm to transfer said charges from said second chambers into said connected chambers caused by the movement of the associated arms, to thereby compound the operation of said charges in said first chambers and operate said engine as a compound engine; means sealing said side portions of said rotor and arms with respect to said housing end walls; and exhaust means comprising exhaust ports provided in at least one of said end walls and a mating valving portion provided on an adjacent arm, each of said ports being arranged to be closed by said valving portion when saId adjacent arm is in said outward position and to open into fluid communication with one of said first fluid chambers when said adjacent arm is moved to said inward position.

6. A rotary engine in accordance with claim 5 wherein each of said exhaust ports is arranged to open into fluid communication with the first expandable fluid chamber defined by said preceding arm and wherein the mating valving portion opens each of said ports after the free end of said adjacent arm has engaged said first portion of said rotor and said adjacent arm has swung inwardly through a selected arc, so that the exhaust of fluid from said first fluid chamber of said preceding arm starts after torque has been transmitted to said rotor by said adjacent arm.

7. In a power system having a source of externally pressurized working fluid and outlet means for directing pressurized fluid from said source, the improvement comprising a rotary engine driven by said externally pressurized working fluid, said engine comprising: a housing defining a generally cylindrical rotor sapce having parallel end walls; a rotor mounted on a shaft within said rotor space, said rotor having a substantial transverse surface and side portions spaced adjacent said end walls; a plurality of elongate arms positioned within conforming arm recesses provided around the inner periphery of said housing and spaced uniformly with respect to said rotor, each of said arms having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged within the associated arm recess and an inward position engaged with said rotor surface; a horn member provided on each of said arms intermediate said arm ends and projecting outwardly into the associated arm recess, each of said horn members being positioned to slide in the associated recess in sealing engagement with said housing as said arms move between said inward and outward positions; said rotor surface including a first segment sequentially engageable with the free ends of said arms as said rotor rotates to permit said arms to move inwardly from said outward position and a second segment sequentially engageable with the free ends of said arms as said rotor continues to rotate to return each arm to said outward position; a plurality of first expandable fluid chambers defined by said housing and the free ends of said arms; a plurality of second expandable fluid chambers defined by said arm recesses and the associated arms and sealed from said first chambers by said arm horn members; means connecting said second chambers in fluid communication with said system outlet means for directing said pressurized working fluid into said second chambers; valve means operable to sequentially admit charges of said pressureized working fluid from said system outlet means into said second chambers when said first segment of said rotor surface is positioned adjacent the free end of the associated arm so that said fluid charges operate within said second chambers and forcefully urge the associated arm inwardly against said rotor and thereby impart a torque force to said rotor and shaft; transfer channel means connecting each of said second chambers to the first chambers associated with the adjacent following arm to transfer said charges from said second chambers into said connected first chambers in response to the change in volume of said connected chambers caused by the movement of associated arms, to thereby compound the operation of said charges in said first chambers and operate said engine as a compound engine; exhaust means in fluid communication with each first fluid chamber and arranged so that outward movement of said arms and continued rotation of said rotor forces the fluid from said first chambers through said exhaust means; and means sealing said side portions of said rotor and said arms with respect to said housing end walls.

8. The power system in accordance with claim 7 wherein said pressurized working fluid comprises compressed gas.

9. The power system in accordance with claim 7 wherein the change in volume of the connected first and second chambers occurs at substantially the same rate so that the fluid charge is transferred through said channels without performing substantial work on the fluid.

10. The power system in accordance with claim 7 wherein said source of working fluid comprises a vapor generator and wherein said pressurized working fluid comprises vapor.

11. The power system in accordance with claim 10 wherein said pressurized working fluid comprises superheated vapor.

12. In a power system having a source of externally pressurized working fluid and outlet means for directing pressurized fluid from said source, the improvement comprising a rotary engine driven by said externally pressurized working fluid, said engine comprising: a housing defining a generally cylindrical rotor space having parallel end walls; a rotor mounted on a shaft within said rotor space, said rotor having a substantial transverse surface and side portions spaced adjacent said end walls; a plurality of elongate arms positioned within conforming arm recesses provided around the inner periphery of said housing and spaced uniformly with respect to said rotor, each of said arms having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged within the associated arm recess and an inward position engaged with said rotor surface; a horn member provided on each of said arms intermediate said arm ends and projecting outwardly into the associated arm recess, each of said horn members being positioned to slide in the associated recess in sealing engagement with said housing as said arms move between said inward and outward positions; said rotor surface including a first segment sequentially engageable with the free ends of said arms as said rotor rotates to permit said arms to move inwardly from said outward position and a second segment sequentially engageable with the free ends of said arms as said rotor continues to rotate to return each arm to said outward position; a plurality of first expandable fluid chambers defined by said housing and the free ends of said arms; a plurality of second expandable fluid chambers defined by said arm recesses and the associated arms and sealed from said first chambers by said arm horn members; transfer channels connecting each second fluid chamber in fluid communication with a first fluid chamber associated with another arm; conduit means connecting each first fluid chamber in fluid communication with the second chamber associated with the same arm; transfer valve means in fluid communication with said first chambers and selectively operable in one position to sequentially direct charges of said pressurized fluid into said chambers so that said charges operate simultaneously in the first and second chambers connected by said conduit means and impart a force to the adjacent arm when said first segment of said rotor is positioned adjacent the free end of said adjacent arm, to operate said engine as a simple engine; said transfer valve means being further operable in a second position to sequentially direct charges of said fluid into said second chambers for intial operation when said first segment of said rotor is positioned adjacent the free end of the associated arm so that the following movement of said arms changes the volumes of the first and second chambers connected by said transfer channels and transfers said charges from said second chambers to said first chambers through said transfer channels, to permit said charges to expand further in said first chambers and thereby operate said engine as a compound engine; exhaust means in fluid communication with each first fluid chamber and arrangeD so that outward movement of said arms forces the fluid from said second chambers into the connected first chamber and forces the fluid from said first chambers through said exhaust means; and means sealing said side portions of said rotor and arms with respect to said housing end walls; whereby said transfer valve means permits said engine to be switchable between simple and compound modes of operation.

13. A power system in accordance with claim 12 wherein the volumes of the first and second chambers connected by said transfer channels change at substantially the same rate as the fluid charge is transferred through said transfer channels from the first chambers to the connected second chambers so that the fluid transfer occurs without performing substantial work on the fluid.

14. A method of transmitting torque to the output shaft of an engine having a rotor mounted on said shaft and disposed within a sealed housing having a plurality of swinging arms uniformly positioned around the rotor within the housing and adapted to impart a torque force to the rotor when driven inwardly against the rotor, with said arms including arcuate projections extending outwardly in sliding engagement with said housing, said projections and housing defining first and second expandable fluid chambers adjacent each of said arms, said method of comprising the steps of: providing the engine with a source of externally pressurized working fluid; admitting a first charge of said pressurized working fluid from said source into each of said first fluid chambers so that the charges operate within said first chambers against the associated arms and drive said arms inwardly against said rotor; timing the admission of said charges into said first fluid chambers so that the operation of said charges within said first chambers drives said arms sequentially inward against said rotor; transferring said charges from each of said first fluid chambers into the second fluid chamber provided adjacent another arm; further directing said fluid charges in said second chambers inwardly against the rotor and the adjacent arms to drive the adjacent arms inwardly against the rotor; admitting a second charge of pressurized working fluid from said source into each of said first fluid chambers; timing the admission of said second charges with said valve means so that said second charges operate inwardly against the associated arm simultaneously with the operation of said transferred charges within said second chambers; and sequentially exhausting each of said charges from said second fluid chambers after said further operation through exhaust means timed so that the exhaustion of fluid from said second chambers begins after the overlapping operation of said second charges in said first fluid chambers; whereby a continuous torque force is transmitted to said rotor by the overlapping operation of charges of pressurized working fluid against said rotor and arms and the operation of each charge of fluid is compounded to provide said engine with a compound mode of operation.

15. The method in accordance with claim 14 wherein said fluid charges are transferred from said first chambers to said second chambers without performing substantial work on the transferred fluid.

16. The method in accordance with claim 14 wherein said pressurized working fluid comprises compressed gas.

17. The method in accordance with claim 14 wherein said source of working fluid comprises a vapor generator, and wherein said pressurized working fluid comprises vapor.

18. The method in accordance with claim 17 wherein said vapor comprises superheated vapor.

19. A method of transmitting torque to the output shaft of an engine having a rotor mounted on said shaft and disposed within a sealed housing and having a plurality of swinging arms uniformly positioned around the rotor within the housing and adapted to impart a torque force to the rotor when driven inwardly Against the rotor, with arms including arcuate projections extending outwardly in sliding engagement with said housing, said projections and housing defining first and second expandable fluid chambers adjacent each of said arms, said method comprising the steps of: providing the engine with a source of externally pressurized working fluid; admitting a first charge of said pressurized working fluid into each of said first and second chambers so that said first charge operates within adjacent first and second chambers simultaneously against the same arm to drive the arm inwardly against said rotor; timing the admission of said first charges into said chambers so that the operation of said first charges drives said arms sequentially inward against said rotor and so that the operation of said first charges against the rotor and the adjacent arms overlap in time; sequentially exhausting said first charges from said chambers; admitting a second charge of said pressurized working fluid into each of said first chambers; timing the admission of said second charges into said first chambers so that the operation of said charges against said arms drives said arms sequentially inward against said rotor; transferring said second charges from each of said first chambers into the second chamber provided adjacent another arm; directing said second charges in said second chambers inwardly against the adjacent arms to further drive said arms sequentially inward against said rotor; and sequentially exhausting each of said second charges from said second chambers; whereby said first charges of working fluid operate said engine as a simple engine and said second charges of working fluid operate said engine as a compound engine.

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