Porting Arrangement For Rotary Machine

Abstract

A rotary piston type four cycle internal combustion engine embodying a pressure responsive check valve in the induction system for reducing gas back flow resulting from port overlap common with this type of mechanism.

Parent Case Text

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of my application of the same title, Ser. No. 813,934, filed Apr. 7, 1969, and now abandoned.

Description

BACKGROUND OF THE INVENTION

This invention relates to a porting arrangement for a rotary machine and more particularly to a system for precluding back flow during overlap conditions.

Rotary piston machines have been proposed for a wide variety of applications. These machines are generally less complex than the conventional reciprocating piston machine since they require no connecting rods or crankshafts as such and balancing is less of a problem since there are substantially no reciprocating masses. In addition, this type of machine requires no intake or exhaust valves since the relative motion of the piston and its outer housing permits the use of porting. The geometry of such mechanisms, however, generally results in a relatively high degree of overlap between the opening of the intake port and the full closing of the exhaust port. This inherent high degree of overlap decreases the efficiency of the machine since a certain percentage of the high pressure exhaust products flow back into the induction port during the overlap period. If the mechanism is utilized as an internal combustion engine, it generally has poor low speed torque and high fuel consumption due to this back flow condition.

In order to prevent or reduce this back flow condition, it has been proposed to employ a butterfly type valve in the induction system of the engine. Such a butterfly valve will have some tendency to reduce back flow, but this type of valve, due to its inertia and other characteristics, tends to remain in a fixed, flow restricting position at a given engine speed and load. That is, the butterfly type valve is not sufficiently pressure responsive to open and close each time there is an overlap condition and the exhaust gases have a higher pressure than the gases in the induction system. In addition, starting and low speed running may be adversely affected by the use of such valves unless they are provided with cut outs to bypass the valve during such conditions. The geometry of such a rotary valve also is such that the valve must be placed at a distance from the chambers of the mechanism. For optimum efficiency, such a valve should be placed as closely adjacent the chamber as possible so that the exhaust gases cannot back up into the portion of the induction system between the valve and the chamber.

It is, therefore, the principal object of this invention to provide an improved porting arrangement for a rotary machine.

It is another object of the invention to provide a rotary machine embodying a pressure responsive check valve in the induction system for precluding the back flow of exhaust fluids into the induction system.

It is another object of the invention to provide an improved rotary piston four cycle internal combustion engine having pressure responsive valving in the induction system.

SUMMARY OF THE INVENTION

This invention is adapted to be embodied in a ported expansible chamber device for precluding back flow during overlap conditions. Such a device is comprised of a pair of members that are supported for relative movement and which define a chamber, the volume of which varies upon such relative movement. Intake port means communicate with the chamber for introducing a fluid to the chamber as its volume increases. Exhaust port means also communicate with the chamber for receiving fluid from the chamber as its volume decreases. The intake port means and the exhaust port means each terminate in an opening in a first of the members in registry with the chamber. The relative movement of the members is effective to bring the second of the members into confronting relationship with each of the openings for precluding flow through the respective of the ports and into a spaced relationship from each of the openings for permitting flow through the respective of the ports. There is a time during the cycle of relative movement when both of the ports are at least partially opened to the chamber. Pressure responsive check valve means are provided at one of the ports for precluding cross flow between the ports when they are both opened.

A further feature of the invention is adapted to be embodied in a rotary piston internal combustion engine for precluding back flow of exhaust gases during an overlap condition. This type of engine has an outer housing that defines a cavity in which a rotor is positioned. Means on the rotor engage the outer housing for dividing the cavity into at least two chambers. The outer housing and rotor are supported for relative rotation whereby the chambers vary in volume during such relative rotation. Intake port means formed at least in part in the outer housing open into the cavity and exhaust port means also formed at least in part in the outer housing open into the cavity. The rotor is adapted to open and close the port means upon the relative rotation between the rotor and outer housing for sequentially presenting each of the chambers to the intake port and to the exhaust port for delivering a charge to the chambers and for exhausting a burnt charge therefrom. In such an engine the invention comprises the provision of pressure responsive check valve means in the intake port for precluding reverse flow from the chambers into the intake port when the pressure in the chamber exceeds that in the intake port. The pressure responsive check valve means is adapted to open when the pressure in the intake port exceeds the pressure in the chamber that is in registry with this port.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a rotary piston internal combustion engine embodying this invention with certain of the components of the engine removed.

FIG. 2 is a side elevational view of the engine shown in FIG. 1.

FIG. 3 is an enlarged cross-sectional view taken along the line 3--3 of FIG. 2.

FIG. 4 is an enlarged top view of the upper end plate of the engine, with portions broken away, taken generally in the direction of the line 4--4 in FIG. 2.

FIG. 5 is an enlarged cross-sectional view taken along the line 5--5 of FIG. 4.

FIG. 6 is an enlarged cross-sectional view taken along the line 6--6 of FIG. 4.

FIG. 7 is a flat pattern view taken generally along the line 7--7 of FIG. 3 and is on an enlarged scale.

FIG. 8 is an enlarged view of the area encompassed by the circle 8 in FIG. 4 with portions broken away.

FIG. 9 is a cross-sectional view taken along the line 9--9 of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A four-cycle internal combustion engine embodying this invention is identified generally by the reference numeral 11 and is depicted in the drawings with certain supporting equipment such as the fuel tank, carburetor and muffler removed for sake of illustration. The engine 11 includes an outer housing assembly 12 in which an output shaft 13 is supported for rotation. The engine 11 is designed so that the output shaft 13 may be disposed vertically, as shown in the drawings, or horizontally. To assist in the vertical mounting, mounting bosses or lugs 14 are formed upon the lower portion of the outer housing assembly 12 and particularly at the base of an oil sump casting, indicated generally by the reference numeral 15. Side mounting bosses 16 are also formed in the outer housing assembly 12 and sump casting 15 so that the engine 11 may be mounted with the output shaft 13 extending in a horizontal direction.

Referring now primarily to FIG. 3, the outer housing assembly 12 includes a central member 20 that is formed with a cavity 17 in which a rotor, indicated generally by the reference numeral 18 is supported. The opposite ends of the cavity 17 are closed by lower and upper end walls 19 and 21, which end walls are affixed to the central member 20 in any known manner. The rotor 18 has a shape which, as will become more apparent as this description proceeds, generally resembles a triangle having apex portions 22, 23, and 24. Apex seal 25, 26, and 27 are carried in complementary grooves formed in the apex portions 22, 23, and 24 and engage the inner surface of the outer housing 12 that defines the cavity 17 to divide the cavity 17 into three chambers 28, 29, and 31. Compression and oil seals 32 and 33 are received in circular grooves formed in opposite faces of the rotor 18 and engage the lower and upper face plates 19 and 21, respectively, to complete the sealing of the chambers 28, 29, and 31.

The rotor 18 is formed with a cylindrical bore 34 that forms a bearing surface which engages a complementary bearing surface 35 formed on an eccentric 36. The eccentric 36 is, in turn, affixed to the output shaft 13 with its surface 35 being eccentrically disposed with respect to the axis of rotation of the output shaft 13. The output shaft 13 is journaled in the top plate 21 and oil sump casting 15, in any known manner.

As is well known with this type of mechanism, timing gears (not shown) are provided to move the rotor 18 relative to the outer housing 12 as these elements undergo relative rotation. These timing gears comprise an internal gear fixed relative to the rotor 18 and an external gear fixed relative to the outer housing assembly 12. The gears may be employed as an oil pump as described in my copending application entitled "Pump for Rotary Machine," Ser. No. 813,891, Filed Apr. 7, 1969, which application issued as U.S. Pat. No. 3,583,371 on June 8, 1971. During the relative rotation, the rotor apex seals 25, 26, and 27 sweep across the surface 17 of the housing 12 and the volumes of the chambers 28, 29, and 31 alternately increase and decrease in volume.

In this type of mechanism, it has been proposed to embody a generated shape for the cavity 17 with the rotor 18 having an external configuration that constitutes the inner envelope of this generated shape. The use of such geometry is described in the British Patent to Millard, No. 583,035, accepted Dec. 5, 1946. The shape of the surface 17 is, however, not a truly generated shape since such true shapes are difficult to form. As is noted in the British Millard patent, the shape of the cavity in the outer housing is generated by a point on a line that extends tangentially to an eccentric circle and which revolves around this circle. It has been found that if the ratio of the length or radius of the generating line to the radius of the eccentric circle is approximately equal to 8.5, the generated shape may be closely approximated by an oval shape. Such a configuration, therefore, is incorporated in the disclosed engine.

One of the advantages of this type of mechanism is its simplicity due to the fact that the relative rotation between the rotor 18 and outer housing assembly 12 permits the use of porting for controlling the admission of the charge to the chambers 28, 29, and 31 and for exhausting the burnt charge from these chambers. The geometry of the mechanism, however, results in considerable overlap between the opening of the intake port and the closing of the exhaust port. As has been noted, this inherent overlap reduces the low speed torque of the engine and reduces its efficiency. A system, now to be described, eliminates or substantially reduces the back flow of exhaust products into the induction system during this overlap condition thus improving the low speed torque and efficiency.

Referring specifically to FIGS. 4 through 6, the upper end plate 21 is formed with an induction passage 41 which terminates at its outer end in a flange 42 that is adapted to support a carburetor (not shown). The other end of the induction passage 41 terminates at a generally circumferentially extending passage 43 that is formed in parts in the uppermost face of the end plate 21. Reinforcing ribs 44 extend across the passage 43 at spaced intervals. The ribs 44 do not extend the full heights of the passage 43 so that a full line of gas flow is provided. In addition, a smaller circumferentially extending passage 45 that extends through these reinforcing ribs 44 and through the lower face of the upper end plate 21. The passage 45 opens into the cavity 17 in an area between the end seals 32 and 33 of the rotor 18 regardless of the angular position of the rotor 18.

Referring now to FIGS. 3 and 7, the rotor 18 is generally open in the area between the seals 32 and 33 with the outer portion of the rotor 18 being connected to its inner portion by means of a first series of flow directing vanes 46 and a second series of vanes 47. The vanes 46 are disposed at an angle to the upper face plate 21 and terminate at their uppermost end adjacent this plate. The lower ends of the vanes 46 terminate at a spaced distance from the lower end plate 19 so as to permit flow of gases from one side of each of the vanes 46 to the other side. The vanes 47 are disposed at an angle to the lower end plate 19 and terminate at their lower ends adjacent this end plate. The upper ends of the vanes 47 are spaced from the end plate 21 so as to permit flow between these vanes and the top end plate 21. With the rotor 18 rotating in a clockwise direction, as viewed in FIG. 3, which direction is indicated by the arrow 48 in FIG. 7, the induction charge will pass into the hollow interior of the rotor through the circumferential passage 45 and will be circulated through the rotor along a path determined by the angular disposition of the vanes 46 and 47 as shown by the flow arrows in FIG. 7.

This flow of induction air through the rotor 18 will assist in the cooling of the rotor 18 and will help dissipate the localized heat generated by the combustion of the gases within the respective chambers 28, 29 and 31 as they pass a spark plug 49 positioned within the central portion 20 of the outer housing assembly 12. It should be noted that the induction charge is introduced into the rotor 18 adjacent the area where combustion occurs. Hence, the coolest portion of the gases will be introduced at the area where the heat generated is the greatest.

Referring again to FIGS. 4 through 6 and additionally to FIGS. 8 and 9, second and third circumferentially extending passages 51 and 52 are formed in the top end plate 21 and extend upwardly from the cavity 17 in an area adjacent the rotor 18 and between its end seals 32 and 33. These passages 51 and 52 permit the induction charge to flow from the hollow interior of the rotor 18 into larger passages 53 and 54 formed in the upper face of the end plate 21. The passages 53 and 54 are separated from the passage 43 adjacent each of its ends by ribs 55 and 56. The ribs 55 and 56 extend the full height of the passages 43, 53, and 54. A gasket (not shown) and a cover plate 57 cover the upper ends of the passages 43, 53 and 54 and assist in the separation of the passage 43 from the passages 53 and 54. The cover plate 57 also completes the definition of the intake passages.

The passages 53 and 54 intersect each other adjacent an upstanding boss 58 upon which a pressure responsive check valve assembly, indicated generally by the reference numeral 59, is supported. The boss 58 extends only partially into the passages 53 and 54 (FIG. 9) so as to permit free communication between these passages.

Referring specifically to FIGS. 8 and 9, the check valve assembly 59 positioned upon the boss 58 is comprised of three reed type check valves 61, 62, and 63. The valves 61, 62 and 63 are each apertured at one end for receipt of dowel pins 64 which serve to locate the check valves 61, 62, and 63. A valve plate 65 is affixed in confronting relationship to the valves 61, 62, and 63 by means of bolts 66 and 67 that extend through elongated slots 68 and 69 formed in the reeds 61 and 63, respectively. The bolts 66 and 67 are tapped into suitably threaded apertures formed in the boss 58 and hold the reed valves against a gasket 70. To support the central portion of the valve plate 65, an upstanding boss 71 extends through an elongated opening 72 formed in the reed 62 and engages the underside of the valve plate 65. In addition to passing the bolts 66 and 67 and boss 71, the reed apertures 68, 69, and 72 serve to provide for a control of the rate of the reed valves.

The valve plate 65 is formed with openings 73 in registry with the lower ends of each of the reed valves 61, 62, and 63. The openings 73 have generally the shape of a convergent nozzle as should be evident from an inspection of FIG. 9.

The downstream sides of the reed valves are exposed to an intake port 75 formed in the boss 58 of top end plate 21. The port 75 is adapted to sequentially register with the chambers 28, 29 and 31 upon relative rotation of the rotor 18. The end plate 21 is formed with a curved surface 76 adjacent the port 75 and on the underside of the lower ends of the reeds 61, 62 and 63. When one of the chambers 28, 29 and 31 is presented to the intake port 75 and the volume of this chamber is increasing due to the relative rotation of the rotor 18, a decreased pressure or suction will be exerted on the downstream side of the reeds 61, 62, and 63. The higher pressure acting on the upper sides of the reeds 61, 62, and 63 through the openings 73 in the valve plate 65 urges the reeds to an open position as shown in FIG. 9. The curved shape of the surface 76 limits the loading on the reeds 61, 62, and 63 thus ensuring long life for these components.

After a charge has been drawn into respective of the chambers 28, 29, and 31, it is compressed by the chamber volume decreasing due to rotation of rotor 18, and 15 fired by the spark plug 49 at the appropriate timing interval. The burnt charge will expand driving the rotor 18 and output shaft 13 in a known manner. After the expansion, the chambers will be sequentially presented to an exhaust port 78 formed in the housing central portion 20. The exhaust port 78 extends through a flange 79 to which a muffler (not shown) may be attached in any known manner. Thus, the burnt charge is discharged to the atmosphere.

As is well known with this type of machine, the movement of the rotor 18 relative to the outer housing assembly 12 causes the intake port 75 to commence opening prior to the time when the exhaust port 78 is fully closed. There is a considerable degree of overlap between this opening, for example in a typical engine constructed in accordance with this invention, the degree of overlap is approximately 60.degree. of rotation of the output shaft 13 or 20.degree. of rotation of the rotor 18 relative to the outer housing assembly 12. Such a high degree of overlap will, in conventional engines of this type, result in back flow of exhaust gases from the chamber that has just expanded to the intake system as this chamber is exposed to the intake port. The disadvantages of this condition have already been stressed and will not be repeated here. In order to prevent such back flow, the reeds 61, 62, and 63 will not open until the pressure in the induction system exceeds the pressure in the respective cavity to which the port 75 is open. Thus, during initial opening of the port 75, the high pressure exhaust gases in the respective cavity cannot enter the induction system and will be substantially discharged from the exhaust port 78.

In addition to precluding the back flow of exhaust gases into the induction system, the pressure sensitive reeds 61, 62 and 63 will have the effect of increasing the effective compression ratio of the engine 11. The relative rotation of the rotor 18 with respect to the cavity 17 causes a compression of the charge that has just been inducted while the intake port 75 is still open. In a conventional engine of this type, the initial compression will have the effect of driving the intake charge back into the port 75. The reed valves 61, 62 and 63 will, however, close under this condition and prevent the loss of any charge.

It should additionally be noted that the reeds 61, 62, and 63 require very little space in their movement between their opened and closed positions. Hence, these reeds may be positioned closely adjacent the cavity 17 thus diminishing the volume between the reeds 61, 62 and 63 and the respective cavities 28, 29, and 31.

While the invention has been described in conjunction with a rotary piston engine operating on a four stroke cycle principle, it may be used in conjunction with other types of rotary machines and in other environments. Also a spark ignition engine has been described, but the invention has the same if not even greater utility in conjunction with a deisel or compression ignition engine. With such an engine, the utility of the reed type valves in precluding the loss of effective compression ratio are particularly important. In addition, although the outer housing assembly 12 was stationary and the rotor 18 rotated, any of the well known kinematic variations possible with this type of mechanism can be employed. For example, both the outer housing and rotor may rotate or the rotor could be fixed with the outer housing rotating. Such other variations and applications will be obvious to those skilled in the art.

Claims

I claim:

1. An expansible chamber device comprised of a pair of members supported for relative movement and defining a chamber the volume of which varies upon such relative movement, intake port means in communication with said chamber for introducing a fluid to said chamber as its volume increases, exhaust port means in communication with said chamber for receipt of the fluid from the chamber as its volume decreases, said intake port means and said exhaust port means each terminating at an opening in a first of said members in registry during a portion of a complete cycle of such relative movement with said chamber, the relative movement of said members being effective to bring the second of said members into confronting relationship with each of said openings during a portion of a complete cycle of such relative movement for precluding flow through the respective of said ports and to position the second of said members in a spaced relationship from each of said openings for permitting flow through the respective of said ports, there being a time during the complete cycle of relative movement when both of said port openings are at least partially opened to said chamber, the intake port opening being formed in a wall of said one member, pressure responsive check valve means in said intake port and movable between an opened position and a closed position, said check valve means comprising reed type valve means, said reed type valve means having one end juxtaposed to said wall and a free end, a valve plate affixed to said wall and retaining said one end of said reed type valve means thereagainst, said valve plate being formed with an opening adjacent said free end of said reed type valve means with which said free end cooperates for controlling flow therethrough, said free end of said reed type valve means being movable between its opened position and its closed position in response to instantaneous pressure changes for precluding flow through said valve plate opening and for precluding cross flow between said ports when both of said ports are opened, and a seat formed by said wall against which said reed type valve means moves in its opened position, said seat being formed for permitting flow through said intake port and for limiting the degree of stress on said reed type valve means.

2. An expansible chamber device as set forth in claim 1 wherein the pair of members are supported for relative rotation.

3. An expansible chamber device as set forth in claim 2 in which the mechanism comprises an internal combustion engine operating on a four cycle principle.

4. An expansible chamber device as set forth in claim 1 wherein there are a plurality of reed valves in the intake port each of which cooperates with the seat, the valve plate being formed with a like number of openings, the free ends of each of said valves cooperating with a respective of said openings.

5. An expansible chamber device as set forth in claim 4 wherein the valve plate openings have a nozzle like configuration.