Background of the Invention Internal combustion engines are limited in that the torque is limited to the configuration of the crank assembly.

Object of the Invention It is the object of the present invention to overcome or substantially ameliorate the above disadvantage.

Summary of the Invention There is disclosed herein a crank assembly having: a primary shaft having a longitudinal axis about which the primary shaft is driven; a link shaft having a longitudinal axis and being attached to the primary shaft to transmit power thereto; coupling means attaching the link shaft to the primary shaft so as to provide for rotation of the link shaft about the longitudinal axis of the link shaft, as well as rotation of the longitudinal axis of the link shaft about the longitudinal axis of the primary shaft; cam means engaging the link shaft to govern rotation of the longitudinal axis of the link shaft about the longitudinal axis of the primary shaft; an internal gear surrounding the longitudinal axis of the primary shaft; an external gear mounted on the link shaft and fixed thereto while being meshingly engaged with the internal gear so that rotation of the longitudinal axis of the link shaft about the longitudinal axis of the primary shaft will cause rotation of the link shaft about the longitudinal axis of the link shaft, the external gear being maintained in meshing engagement with the internal gear by the cam means; and a connecting rod being attached to the link shaft to permit relative rotation therebetween, which connecting rod is driven so as to cause rotation of the longitudinal axis of the link shaft about the longitudinal axis of the primary shaft.

Brief Description of the Drawings A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein: Figure 1 is a schematic side elevation of a crank mechanism for an internal combustion engine; Figure 2 is a schematic end elevation of the crank mechanism of Figure 1; and

Figures 3,4 and 5 schematically depict modifications of the crank mechanism of Figures 1 and 2.

Detailed Description of the Preferred Embodiments In the accompanying drawings there is schematically depicted a crank mechanism 10 having a connecting rod 11 extending to a piston of an internal combustion engine.

Accordingly, the connecting rod 11 is driven.

The crank mechanism 10 includes a support 12 which rotatably supports a primary shaft 13 for rotation about its longitudinal axis 14. The primary shaft 13 is attached to a flywheel 15.

Drivingly connected to the shaft 13 is a link shaft 16, by means of a universal coupling mechanism 17. The coupling mechanism 17 provides for the transfer of rotary power from the shaft 16 to the shaft 13, while still permitting rotation of the longitudinal axis 18 of the shaft 16, about the longitudinal axis 14.

The extremity of the shaft 16 is provided with a cam follower in the form of a roller 19. The roller 19 is rotatable about the axis 18 and engages a cam surface 20 of a cam member 21.

Fixed to the shaft 16 is an external gear 22 which is meshingly engaged with an internal gear 23. The cam surface 20 via the roller 19 maintains the external gear 22 in meshing engagement with the internal gear 23.

Also attached to the shaft 16 is the connecting rod 11 by means of a pivot assembly 24 enabling rotation of the shaft relative to the rod 11. The piston associated with the connecting rod 11 causes movement of the shaft 16 and therefore rotation about the longitudinal axis 14. Meshing engagement of the gears 22 and 23 causes rotation of the shaft 16 about its longitudinal axis 18 and therefore rotation of the shaft 13 about its longitudinal axis 14.

The internal gear 23 is provided with two arcuate portions 25 joined by generally linear portions 26. In that respect it should be appreciated that the cam surface 20 is of a similar configuration. The external gear 22 is generally circular in configuration.

The above described preferred embodiment has the advantage that an internal combustion engine incorporating the crank mechanism 10, has increased torque. If so required, the crank mechanism 10 may be re-configured so as to provide an associated piston with a conventional stroke length, while still increasing the torque.

In the embodiments of figures 3 to 5, the reference numerals employed in the previous drawings have been continued.

In the embodiment of figure 3, the internal gear is circular in configuration with a centre at the intersection of the axis 27 and 28. The cam member 21 has its external cam surface 20 of a corresponding configuration, that is circular.

In this embodiment the stroke of the piston is equal to the displacement of the cam follower 19 from the position"E"to the position"F". Thus the stroke of the engine can remain the same but the tongue is increased at the shaft 16. In this embodiment the rod 11 is attached to the shaft 16 by a roller bearing 37.

In the embodiment of figure 3 the connecting rod 11 may be directly pivotally attached to the gear 22. Such an attachment may typically include the universal joint.

In the embodiment of figure 4, the cam member 21 is elongated so that the external surface 20 has 2 generally parallel co-extensive linear portions 29 and 30, with arcuate end portions 31. The internal gear 23 has corresponding configuration in that it includes linear portions 32 joined by an arcuate portion 33. The external gear 22 is circular in configuration matching the end portions 33. The rod 11 is attached to the gear 22 adjacent the periphery thereto. The stroke of the engine will not change, however the tongue delivered to the shaft 16 will increase.

In the embodiment of figure 5, the internal gear 23 is of a"D"configuration in that it includes a linear portion 34 and an arcuate portion 35. The cam member 21 is of a complimentary configuration in that it also includes a linear portion 36 and an arcuate portion 37.

The gear 22 is circular.

The linear portions 34 and 36 would correspond to the power stroke of the piston.