1. Field of the Invention
The present invention relates to an internal combustion engine having a nutating member. The engine also has provision for continuously varying engine parameters such as displacement, compression ratio, valve timing, and valve lift.
2. Description of the Prior Art
It has been known in the art that the traditional fixed-geometry internal combustion engines cannot perform optimally over their entire operational rpm and torque range. For this reason, many designs have been proposed in the prior art that allow the variation of one or several of the more important engine parameters such as compression ratio, displacement, and valve timing.
U.S. Pat. No. 5,165,368, issued to Schechter, shows a variable compression ratio engine where the compression ratio is varied by varying the crank radius using a mechanical and hydraulic mechanism responsive to the torsional impulses applied through the connecting rod. The Schechter system cannot vary the compression ratio independent of the piston stroke.
U.S. Pat. No. 5,136,987, issued to Schechter et al., shows a variable piston stroke engine where the piston stroke is varied by varying the length of an arm extending between the connecting rod pivot, distal from the piston, and the engine block. Again the Schechter et al. system does not permit the independent variation of the compression ratio and the piston stroke.
U.S. Pat. No. 4,270,495, issued to Freudenstein et al., shows a variable stroke engine where the stroke is varied by changing the pivot point of a rocker arm extending between the connecting rods of two adjacent cylinders.
U.S. Pat. No. 4,131,094, issued to Crise, shows a variable stroke engine where the stroke is varied by varying the crank radius. Again the Crise system does not permit the independent variation of the compression ratio and the piston stroke.
U.S. Pat. No. 4,100,815, issued to Kemper, shows a variable displacement engine where the displacement is varied by the rotation of an eccentric sleeve relative to a nutating member. The Kemper engine suffers from the serious drawback that the nutating member is constrained from rotation about the output shaft only by the forces exerted on the pistons by the cylinder walls. Thus the reaction torque on the nutating member is borne entirely by the piston sides and cylinder walls. For this reason the Kemper engine would suffer from rapid wear damage to the cylinder walls and piston sides resulting in their premature failure. Further, in the Kemper engine the forces of the pistons act at a distance from the axis of the output shaft, which is greater than the distance, from the axis of the output shaft, of the forces between the nutating member and the rotating support member. The greater moment arm of the piston forces greatly amplifies the forces on the bearing surfaces of the nutating member and the rotating support member, thus leading to faster wear and consequent mechanical failure.
U.S. Pat. No. 4,066,049, issued to Teodorescu et al., shows a variable displacement engine where the displacement is varied by moving the bracket supporting the nutating member relative to the cylinder block. The Teodorescu et al. engine suffers from the same drawbacks enumerated with respect to the Kemper engine. In addition, there are no discernable means in the Teodorescu et al. engine for counteracting the torque on the output shaft of the engine. Although Teodorescu et al. do not explicitly state how the connecting rods attach to the pistons, the geometric constraints imposed by nutation of the equatorial band of the Teodorescu et al. engine would dictate that the piston rods should be ball-jointed at both ends. Therefore, the only rotational constraint on the equatorial band of the Teodorescu et al. engine would be the piston rods crashing into the bottoms of the cylinder bores. It should be readily apparent that such an arrangement would lead to rapid wear and consequent premature mechanical failure of the piston rods and the cylinder bore bottoms.
French Patent Document Number 2 647 508, by Jurkovic, shows a variable compression ratio engine where the compression ratio is varied by moving the axis of rotation of the crank shaft relative to the cylinder block.
German Patent Document Number 27 53 563, by Zeilinger, shows a variable compression ratio engine where the compression ratio is varied by varying the connecting rod length.
Netherlands Patent Document Number 8901197, by Van Hoeven, shows a variable compression ratio engine where the compression ratio is varied by moving the pivot point of a rocker arm extending between the piston rod and a connecting rod engaging the throw of the crankshaft.
United Kingdom Patent Document Number 2 219 836 A, by Heniges, shows a variable stroke engine where the stroke is varied by changing the crank radius using an eccentric mounted on the crank throw.
United Kingdom Patent Document Number 286,075, by Myers, shows a variable stroke engine where the stroke is varied by a pivoting plate extending between the piston rod and a rod connected to the crankshaft throw. The Myers design does not allow for dynamic control of the piston stroke and compression ratio in response to engine load conditions.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.