Engine system having torsional coupling with thin web flywheel

1. An engine system comprising:

an internal combustion engine including an engine housing and a crankshaft rotatable within the engine housing;

a driven unit including a driven unit housing and a driveshaft rotatable within the driven unit housing;

a torsional coupling rotatable about a center axis to transfer torque between the internal combustion engine and the driven unit, the torsional coupling comprising:

a driven-side disc coupled to the driveshaft; and

a flywheel comprising:

an engine-side disc coupled to the crankshaft, a center of the engine-side disc aligning with the center axis; and

an axially projecting annular flange coupling the engine-side disc to the driven-side disc, the axially projecting annular flange configured to couple the engine-side disc to the driven-side disc coupled to the driveshaft in the driven unit to transfer torque via the torsional coupling between the crankshaft and the driveshaft, wherein the annular flange is irreversibly coupled to the engine-side disc, and reversibly coupled to the driven-side disc,

wherein the engine-side disc comprises:

an inboard region having a first axial thickness and a first radial extent, the inboard region defines a circular opening configured to receive the crankshaft;

an outboard region having a second axial thickness and a second radial extent;

a disc web extending radially between the inboard and outboard regions and oriented about the center axis, the disc web having a third axial thickness and a third radial extent,

wherein the first radial thickness and the second axial thickness are each greater than the third axial thickness; and

wherein the third radial extent is greater than a sum of the first radial extent and the second radial extent.

2. The engine system of claim 1 , wherein the driver unit further comprises a rotor mounted to the driveshaft, and wherein the rotor and the driveshaft form an assembly rotatable within the driven housing.

3. The engine system of claim 2 , wherein the driven unit further comprises a bearing supporting the assembly of the rotor and driveshaft for rotation within the driven unit housing.

4. The engine system of claim 3 , wherein the third axial thickness is about 0.31 inches.

5. The engine system of claim 2 , wherein the driven unit further comprises an electrical generator and the rotor comprises a permanent magnet rotor of the electrical generator.

6. The engine system of claim 1 , wherein the annular flange includes a tab extending circumferentially around the center axis, and the driven-side disc defines a groove receiving the tab, and the torsional coupling further includes a plurality of bolts reversibly coupling the annular flange to the driven-side disc.

7. The engine system of claim 1 , further comprising:

a bell gear clamped between the engine-side disc and the crankshaft; and

a gear ring coupled to the engine-side disc.

8. A flywheel, for a torsional coupling in an engine system having an internal combustion engine and a driven unit, the flywheel comprising:

an engine-side disc configured to couple to a crankshaft in the internal combustion engine, a center of the engine-side disc defining a center axis; and

an axially projecting annular flange attached to the engine-side disc, the axially projecting annular flange configured to couple the engine-side disc to a driven-side disc coupled to a driveshaft in the driven unit to transfer torque via the torsional coupling between the crankshaft and the driveshaft,

wherein the engine-side disc comprises:

an inboard region having a first axial thickness and a first radial extent;

an outboard region having a second axial thickness and a second radial extent, and being attached to the axially projecting annular flange; and

a disc web extending radially between the inboard and outboard regions and oriented about the center axis, the disc web having a third axial thickness and a third radial extent, the third radial extent is greater than a sum of the first radial extent and the second radial extent;

wherein the first axial thickness and the second axial thickness are greater than the third axial thickness; and

wherein the third axial thickness, is less than 0.25 inches, the third radial extent of the disc web is between 2 times to 3 times a sum of the first radial extent and the second radial extent, and a diameter of the engine-side disc is about 36 inches.

9. The flywheel of claim 8 , wherein the engine-side disc has a first axial side and a second axial side, and wherein the engine-side disc defines a first annular hollow on the first axial side and a second annular hollow on the second axial.