Rotary engine with axially symmetric ring gear

Abstract

Improved rotary engine having a pair of symmetrically arranged ring gears. An improved pistonless rotary engine of the type includes: (i) a rotor having a central axis of rotation and first and second axial surfaces, (ii) a housing having a plurality of working chambers, (iii) a pair of side covers axially disposed on first and second sides of the rotor and coupled to the housing, and (iv) an output shaft coupled to the rotor, the improvement including a pinion gear disposed around the output shaft to support rotation relative to the output shaft, extending through the central axis of the rotor and rigidly coupled to the rotor, and a pair of ring gears symmetrically disposed on opposite sides of the rotor.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority from U.S. Provisional Application No. 63 / 400,797, filed August 25, 2022, the contents of which are incorporated herein by reference in their entirety.

[0002] (Government Rights in Inventions) This invention was made with Government support under Contract No. HR0011-16-9-0009 awarded by DARPA (Defense Advanced Research Projects Agency). The Government has certain rights in this invention.

[0003] (Technical field) The present invention relates to a rotary engine having an axially symmetric ring gear for load sharing during operation. [Background technology]

[0004] Wankel-type rotary engines employ a single ring and pinion gear to control the angular position of the rotor relative to the housing during operation. However, high-compression engines, such as diesel engines, generate much higher dynamic and gas loads than previous generation rotary gasoline engines, and a single ring and pinion gear may be insufficient for their operation. Summary of the Invention [Means for solving the problem]

[0005] In accordance with one embodiment of the present invention, a type of improved pistonless rotary engine includes: (i) a rotor having a central axis of rotation and first and second axial surfaces; (ii) a housing having a plurality of working chambers; (iii) a pair of side covers axially disposed on first and second sides of the rotor and coupled to the housing; and (iv) an output shaft coupled to the rotor, wherein the improvement further comprises a pinion gear disposed around the output shaft to support rotation relative to the output shaft, extending through the central axis of the rotor and rigidly coupled to the rotor, the pinion gear being arranged to support rotation relative to the output shaft. a pinion gear having a first section extending axially beyond the axial surface and a second section extending axially beyond the second axial surface of the rotor and a plurality of teeth circumferentially arranged about its outer radial surface; and a pair of ring gears symmetrically arranged on opposite sides of the rotor, each ring gear fixed to the inner surface of one of the side covers, each ring gear having a plurality of teeth circumferentially arranged about the inner radial surface of each ring gear and configured to engage with teeth of a corresponding one of the pinion gear sections.

[0006] In some embodiments, the teeth of the first section and the second section of the pinion gear are crowned. In some embodiments, each tooth of the ring gear is crowned.

[0007] In some embodiments, each of the ring gears includes a flexible, thin, continuous rim around its periphery.

[0008] In some embodiments, the pinion gear is coupled to the output shaft by a first bearing, which may be a hydrodynamic bearing.

[0009] In some embodiments, each ring gear is secured to an inner surface of one of the side covers by a spring pin. In some embodiments, the output shaft extends through each of the pair of side covers.

[0010] In some embodiments, each of the pair of side covers is coupled to the output shaft by a second bearing. In some embodiments, the second bearing is a hydrodynamic bearing.

[0011] In some embodiments, the inner axial surface of each of the ring gears includes a groove and a series of pad cutouts, the groove and the series of pad cutouts being circumferentially disposed around at least a portion of the circumference of the inner axial surface of each of the ring gears, hi some embodiments, the groove and the series of pad cutouts being circumferentially disposed around the entire circumference of the inner axial surface of each of the ring gears. [Brief explanation of the drawings]

[0012] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0013] The foregoing features of the embodiments will be more readily understood by reference to the following detailed description taken in conjunction with the accompanying drawings, in which:

[0014] [Figure 1] FIG. 1 is a photograph of a rotary engine mounted on a bracket according to one embodiment of the present invention.

[0015] [Figure 2] FIG. 2 is an exploded view of rotary engine components according to one embodiment of the present invention.

[0016] [Figure 3] FIG. 3 is a perspective view of an assembly of the rotary engine components of FIG. 2 according to one embodiment of the present invention.

[0017] [Figure 4] FIG. 4 is a photograph of the rotary engine of FIG. 1 without the side covers, according to one embodiment of the present invention.

[0018] [Figure 5] FIG. 5 is a perspective view of selected components of a rotary engine (in their normal configuration) according to one embodiment of the present invention, the rotary engine having a pair of ring gears symmetrically positioned on opposite sides of a rotor (not shown).

[0019] [Figure 6] FIG. 6 illustrates the misalignment between the pinion gear and the two ring gears, which is evident from the fact that the two ring gears are not symmetrical, according to one embodiment of the present invention.

[0020] [Figure 7] Figures 7A, 7B, and 7C show vertical, horizontal, and rotational misalignment between the pinion gear and ring gear, respectively, according to an embodiment of the present invention.

[0021] [Figure 8] FIG. 8 is a pinion gear with crowning according to one embodiment of the present invention.

[0022] [Figure 9] FIG. 9 is a ring gear with crowning according to one embodiment of the present invention.

[0023] [Figure 10] Figure 10A is a ring gear having a flexible, thin, continuous rim around its periphery according to an embodiment of the present invention. Figure 10B is a perspective view of a portion of the ring gear of Figure 10B according to an embodiment of the present invention.

[0024] [Figure 11]11 is a perspective view of a rotary engine (with side covers and housing removed) from one side of a rotor, the rotor being rigidly fixed to a pinion gear, which is coupled to an output shaft by a bearing (e.g., a hydrodynamic bearing). The pinion gear extends through the central axis of the rotor and has first and second sections that extend axially beyond the axial plane of the rotor, each section engaging a corresponding ring gear.

[0025] [Figure 12] Figure 12A is a cross section of the rotary engine of Figure 1 showing the oil path through the output shaft, and Figure 12B shows the engine cross section and bearing layout, according to one embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] Detailed Description of Specific Embodiments Definitions: As used in this description and the accompanying claims, the following terms shall have the meanings indicated, unless the context otherwise requires.

[0027] The terms "rotary engine" and "pistonless rotary engine" are used interchangeably herein to mean "a rotary engine that includes no pistons."

[0028] A "compliant" coupling of components of a rotary engine according to an embodiment of the present invention means "a coupling providing relative flexibility between the components."

[0029] 1 is a photograph of a rotary engine mounted on a bracket according to an embodiment of the present invention. In some embodiments, the rotary engines described herein include, but are not limited to, engines disclosed in U.S. Patent Nos. 8,863,724, 8,365,699, 8,863,723, 9,353,623, 9,382,851, 9,528,435, 9,644,570, 9,810,068, 10,196,970, 10,125,675, 10,221,690, and 11,149,547 (the disclosures of each of which are incorporated herein by reference in their entirety), and a side view of the engine.

[0030] FIG. 2 is an exploded view of rotary engine components including a first side cover including an end plate 200 and a front plate 202, a housing 204, and a second side cover including an end plate 208 and a back plate 206, in accordance with an embodiment of the present invention.

[0031] FIG. 3 is a perspective view of an assembly of the rotary engine components of FIG. 2 in accordance with an embodiment of the present invention.

[0032] 4 is a photograph of the rotary engine of FIG. 1 without side covers, showing rotor 402 with attached pinion gear 404, output shaft 406, and rotor thrust surface 408 within housing 204, according to an embodiment of the present invention. Pinion gear 404 includes a plurality of teeth arranged circumferentially around its outer radial surface and is rigidly fixed to rotor 402, where the rotor forms three separate working chambers defined by housing 204, front plate 202, back plate 206 (not shown), seals (not shown), and rotor 402 itself. During operation, the rotor oscillates, i.e., moves with its center along a circle defined by the shaft eccentricity, while simultaneously rotating about its center, causing compression of gases in the working chambers and allowing expansion of gases.

[0033] To avoid contact between the rotor 402 and the housing 204 during operation, rotary engines require gearing to ensure that the rotor rotates at half the shaft speed in the opposite direction of the shaft eccentricity. For example, in a Wankel-type rotary engine, a single ring and pinion gear is sufficient to control the angular position of the rotor relative to the housing. However, compression ignition (CI) diesel engines have much higher loads than previous generation rotary gasoline engines and, in various embodiments, benefit from more comprehensive gearing.

[0034] 5 is a perspective view of selected components of a rotary engine embodiment (in their normal configuration) having a pair of ring gears 500 symmetrically positioned on opposite sides of a rotor (not shown) to control the angular position of the rotor, according to an embodiment of the present invention. Ring gear 500 includes a plurality of teeth circumferentially positioned about its inner radial surface, which allow ring gear 500 to engage pinion gear 404. Pinion gear 404 is coupled to output shaft 406 in accordance with an embodiment of the present invention. In some embodiments, pinion gear 404 is coupled to output shaft 406 by a bearing, e.g., a hydrodynamic bearing.

[0035] In some embodiments, a hydrodynamic thrust bearing between the rotor 402 and the ring gear 500 is formed by an oil film between the rotor thrust surface 408 and the inner axial surface of the ring gear 500. Grooves 504 and pad cutouts 502 on the inner axial surface of the ring gear 500 promote greater flexibility by providing increased oil lubrication and flow between the rotor thrust surface 408 and the inner axial surface of the ring gear 500. The grooves 504 and series of pad cutouts are circumferentially disposed around at least a portion of the circumference of the inner axial surface of the ring gear 500. In some embodiments, the grooves 504 and series of pad cutouts are circumferentially disposed around the entire circumference of the inner axial surface of the ring gear 500. In some embodiments, a deeper groove on the inner axial surface of the ring gear 500 can be used to mount a flexible oil ring seal, which also extends over the rotor thrust surface 408.

[0036] The dual ring gear design allows the loads and stresses that would be incurred by a single ring gear to be significantly reduced because these loads and stresses are shared between both ring gears. While the dual ring gear design significantly increases load capacity, it can introduce misalignment between the pinion gear 404 and the two ring gears 500, as illustrated in FIG. 6 (rotor not shown), where the two ring gears are not symmetrical. Such misalignment can cause one of the ring gears to carry a greater load than the other of the ring gears. FIG. 6 further illustrates a pinion gear section 602 that is rigidly fixed to the rotor 402 (not shown) in accordance with an embodiment of the present invention.

[0037] Figure 7A shows vertical misalignment between pinion gear 404 and ring gear 500. Figure 7B shows horizontal misalignment between pinion gear 404 and ring gear 500. Figure 7C shows rotational misalignment between pinion gear 404 and ring gear 500.

[0038] Crowning 802 on pinion gear 404 as shown in FIG. 8 and / or crowning 902 on ring gear 500 as shown in FIG. 9 reduce or eliminate misalignment between pinion gear 404 and ring gear 500. Crowning reduces edge loads on the misaligned gears, while flexibility between pinion gear 404 and ring gear 500 (with or without crowning) allows for slight movement of pinion gear 404 relative to the dual ring gear system, thus distributing loads more evenly between the two ring gears. In some embodiments, flexibility is accomplished by utilizing an oil film to fill the gaps in the hydrodynamic bearings.

[0039] In some embodiments, flexibility can be achieved by using a ring gear 500 with a flexible, thin, continuous rim 1000 (by which the gear is mounted to the side cover) as shown in Figures 10A and 10B. The ring gear with the thin, continuous rim can be mounted to the side cover using a flexible washer, for example, a Belleville washer. The flexible, thin, continuous rim 1000 allows the ring gear 500 to flex under dynamic and gas loads, thus reducing misalignment. In some embodiments, flexibility can be achieved by utilizing a flexible element (e.g., a spring), a flexible bearing structure, or a split pinion gear with a flexible rotor.

[0040] 11 is a perspective view of a rotary engine (with side covers and housing removed) from one side of a rotor 402, according to one embodiment of the present invention, where the rotor 402 is rigidly fixed to a pinion gear 404, which is coupled by a bearing (e.g., a hydrodynamic bearing) to an output shaft 406. The pinion gear 404 extends through the central axis of the rotor 402 and has first and second sections that extend axially beyond the axial plane of the rotor, each section engaging a corresponding ring gear 500.

[0041] FIG. 12A is a cross-section of the rotary engine of FIG. 1 showing oil flow paths, according to one embodiment of the present invention, and FIG. 12B is a cross-section of the rotary engine of FIG. 1 showing oil film locations, according to one embodiment of the present invention. During operation of the rotary engine, hot combustion gases cause an increase in the temperature of the rotor 402 and housing 204. To prevent coking of the lubricating oil film, the rotor and housing must be cooled. Furthermore, to support gas and inertial loads, the rotor is supported by bearings located within the eccentric shaft, which in turn is supported by bearings within the end plates. In a preferred embodiment, these bearings are hydrodynamic and operate with oil as the working fluid. As shown in FIGS. 12A and 12B, oil is supplied internally through channels in the eccentric output shaft to the hydrodynamic bearings, pinion gear 404, ring gear 500, seals, and the rotor itself. FIG. 12B shows one embodiment of the engine cross-section and bearing layout, and FIG. 12A shows one embodiment of the oil path through the output shaft.

[0042] Various embodiments of the present invention may be characterized by potential claims, which are recited in the paragraphs following this paragraph (and before the actual claims provided at the end of this application). These potential claims form part of the written description of this application. Accordingly, the subject matter of the following potential claims may be presented as actual claims in a later proceeding with this application or any application claiming priority based on this application. The inclusion of such potential claims should not be construed to mean that the actual claims do not cover the subject matter of the potential claims. Accordingly, a decision not to present these potential claims in a later proceeding should not be construed as a donation of this subject matter to the public.

[0043] Without limitation, potential subject matter that may be claimed (prefaced with the letter "P" to avoid confusion with the actual claims presented below) includes: P1. An improved pistonless rotary engine of the type including: (i) a rotor having a central axis of rotation and first and second axial surfaces; (ii) a housing having a plurality of working chambers; (iii) a pair of side covers axially disposed on first and second sides of the rotor and coupled to the housing; and (iv) an output shaft coupled to the rotor, the improvement comprising: a pinion gear disposed about the output shaft to support rotation relative to the output shaft, extending through a central axis of the rotor and rigidly coupled to the rotor, the pinion gear having a first section extending axially beyond a first axial surface of the rotor, a second section extending axially beyond a second axial surface of the rotor, and a plurality of teeth disposed circumferentially about an outer radial surface thereof; a pair of ring gears symmetrically disposed on opposite sides of the rotor, each ring gear fixed to an inner surface of one of the side covers, each ring gear having a plurality of teeth circumferentially disposed about an inner radial surface thereof, each ring gear having a plurality of teeth configured to engage with teeth of a corresponding one of the pinion gear segments; Improved pistonless rotary engines, including: P2. The improved pistonless rotary engine of claim P1, wherein the teeth of the first and second sections of the pinion gear are crowned. P3. An improved pistonless rotary engine as claimed in any one of claims P1-P2, wherein each tooth of the ring gear is crowned. P4. An improved pistonless rotary engine as claimed in any one of claims P1-P3, wherein each of the ring gears includes a flexible, thin, continuous rim about its outer periphery. P5. An improved pistonless rotary engine as claimed in any one of claims P1-P4, wherein the pinion gear is coupled to the output shaft by a first bearing. P6. The improved pistonless rotary engine of claim P5, wherein the first bearing is a hydrodynamic bearing. P7. An improved pistonless rotary engine as claimed in any one of claims P1-P6, wherein each ring gear is secured to the inside surface of one of the side covers by a spring pin. P8. An improved pistonless rotary engine as claimed in any one of claims P1-P7, wherein an output shaft extends through each of a pair of side covers. P9. The improved pistonless rotary engine of claim P8, wherein each of the pair of side covers is coupled to the output shaft by a second bearing. P10. The improved pistonless rotary engine of claim P9, wherein the second bearing is a hydrodynamic bearing. P11. An improved pistonless rotary engine as claimed in any one of claims P1-P10, wherein the inner axial surface of each of the ring gears includes a groove and a series of pad cutouts, the groove and the series of pad cutouts being circumferentially disposed around at least a portion of the circumference of the inner axial surface of each of the ring gears. P12. The improved pistonless rotary engine of claim P11, wherein the grooves and series of pad cutouts are circumferentially disposed around the entire circumference of the inner axial surface of each of the ring gears.

[0044] The embodiments of the invention described above are intended to be illustrative only, and numerous variations and modifications will be apparent to those skilled in the art. All such variations and modifications are intended to be within the scope of the present invention, as defined in any appended claims.

Claims

1. 1. An improved pistonless rotary engine of the type including: (i) a rotor having a central axis of rotation and first and second axial surfaces; (ii) a housing having a plurality of working chambers; (iii) a pair of side covers axially disposed on first and second sides of said rotor and coupled to said housing; and (iv) an output shaft coupled to said rotor, the improvement comprising: a pinion gear disposed about the output shaft to support rotation relative to the output shaft, extending through the central axis of the rotor and rigidly coupled to the rotor, the pinion gear having a first section extending axially beyond the first axial surface of the rotor, a second section extending axially beyond the second axial surface of the rotor, and a plurality of teeth disposed circumferentially about an outer radial surface thereof; a pair of ring gears symmetrically disposed on opposite sides of the rotor, each ring gear fixed to an inner surface of one of the side covers, each ring gear having a plurality of teeth circumferentially disposed about an inner radial surface thereof and configured to engage teeth of a corresponding one of the pinion gear segments; Improved pistonless rotary engines, including:

2. 2. The improved pistonless rotary engine of claim 1, wherein said teeth of said first section and said second section of said pinion gear are crowned.

3. 2. An improved pistonless rotary engine according to any one of the preceding claims, wherein the teeth of each of the ring gears are crowned.

4. 2. An improved pistonless rotary engine according to any one of the preceding claims, wherein each of said ring gears includes a flexible thin continuous rim around its periphery.

5. Improved pistonless rotary engine according to any one of the preceding claims, wherein the pinion gear is coupled to the output shaft by a first bearing.

6. 6. An improved pistonless rotary engine according to claim 5, wherein said first bearing is a hydrodynamic bearing.

7. 2. An improved pistonless rotary engine according to any one of the preceding claims, wherein each ring gear is secured to the inner surface of one of the side covers by a spring pin.

8. 2. An improved pistonless rotary engine according to any one of the preceding claims, wherein the output shaft extends through each of the pair of side covers.

9. 9. An improved pistonless rotary engine according to claim 8, wherein each of said pair of side covers is coupled to said output shaft by a second bearing.

10. 10. An improved pistonless rotary engine according to claim 9, wherein said second bearing is a hydrodynamic bearing.

11. 10. An improved pistonless rotary engine as claimed in any one of the preceding claims, wherein the inner axial surface of each of the ring gears includes a groove and a series of pad cutouts, the groove and the series of pad cutouts being circumferentially arranged around at least a portion of the circumference of the inner axial surface of each of the ring gears.

12. 12. The improved pistonless rotary engine of claim 11, wherein said groove and said series of pad cutouts are circumferentially disposed around the entire circumference of said inner axial surface of each of said ring gears.

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