CA2195886C - Multicylinder boxer crankshaft assembly - Google Patents

Abstract

In typical internal combustion engines and compressors, etc., it is known to have a piston, moving in a cylinder, connecting rod and a crankshaft, as a crankshaft system.
The gas and inertia forces press the piston against the cylinder side wall and produce bending stresses in the connecting rod.
With increased speed the effect of inertia forces may exceed this of gas forces. The second harmonic inertia force may cause bigger stresses than its first harmonic. This puts heavy demand on all components, posing limitations to speed and power.
Balancing is also difficult.

Description

25.08.1999.

2,195,886 _3_ 'Jojciech Barski 3. Disclosure: SPECIFICATION
This invention relates to internal combustion engines and compressors, piston driven.
The classical crankshaft mechanism uses piston moving in a cylinder with circular cross section, which both are the best part of it. It is relatively easy to seal the circular piston in a cylinder.
During motion the piston exerts forces on the cylinder wall, resulting from gas or inertia forces, causing the wear of piston and cylinder pair. Piston motion contains a long list of harmonic components, impossible to balance for one cylinder.
The Wankel rotary engine was one of proposed design to depart from the unconvenient crankshaft system, but is plagued by sealing problem of the corner blades, so the durability is low.
The solution proposed by Grundy is only a half-measure, because the reaction of cylinder walls is used to guide the cams, thus does not remove this unwanted effect of side friction and pressure needed to counteract the applied forces.
The original Pitts design also did not find a practical application for piston combustion engines because there will be a backlash on the gears and a play on the crank and main shaft bearings.
The lay-out is sensitive to radial displacements resulting during normal operation. The net result is hammering, pitting, wear or cracks and breaking of teeth.
The backlash will manifest itself in not perfect guidance of the piston, resulting in forces on the cylinder wall, and the hammering contact forces between the gears will cause excessive stresses leading to noise or material failure.
My system proposed here eliminates the dawbacks listed here in the Abstract section and delivers a fully operational, practical, useful and new crankshaft system. The details follow.
Also please see page 6, Picture #1.
Picture #2, page 7 here, shows more general case of my design.

2,195,886 -4- 25.08.1999.
Wojciech Barski - I have found that these drawbacks may be overcome by placing a cam sleeve (7) on the crank of a crankshaft (4), with a running fit. The cam sleeve carries at least one circular cam (8) for a double-sided piston (2) and (13). The piston may be also single, as (2) or (13). The circular cams are offset from the crank axis by the amount equal a crankthrow (see picture #1, lines 00, BB, AA, dimension r). Line AA passes through the centre of circular cam (8).
The circular cam (8) is partially placed into a circular cam ring (10), with a running fit. The cam ring (10) terminates on the left side having a conical planet gear (5). The cam ring (10) may move on the left cylindrical end of the cam sleeve, as well as on the crank.
The cam sleeve at its right end terminates in another conical planet gear (6).
The double sided piston (2) and (13) is fitted on the circular cam (8) with proper play. The pistons (2) and (13) sit in two opposite in line cylinders. The axis of the cylinders intersects with the main bearing axis 00 of the crankshaft. The double piston may be reduced to one.
Another circular cam (9) with its own pistons may be added. The axis of the cylinders has to cut the 00 axis, but the new cylin-ders need not to be in the same plane as the former set of cylin-ders, enabling different configurations of cylinders ( X, cross, U, etc.).
The left conical planet gear (5) meshes with an internal conical gear (3) on the left.
The right conical planet gear (6) meshes with the right internal conical gear (3).
The gear ratio is 1:2. Planet gear has one half of the teeth of the internal gear.
The conical internal gears (3) are installed firmly in the housing.
The oil is supplied also between the cam ring (10) and the cam sleeve (7), and circular cam (8), causing the axial expansion of the planet gears (5) and (6). The oil may flow in via one-directional valve to resist compression of cam ring (10) against cam sleeve(7). In this way there is automatic compensation-elimination of backlash, crucial in rectilinear movement of the circular cam (8), so no side forces are transmitted from piston to the cylinder wall.
The length of teeth contact in conical gears is substantially bigger than for cylindrical gears, so the contact stresses are smaller. The design employs conical gears, which are more of a general class of gears than cylindrical ones. In this sense my design is a generalization of Pitts design, see picture #2.
Conical gears offer far smaller sensitivity to radial plays of the main and crank bearings, or movements caused by gas, inertia or vibrations, so the life of mechanism will be longer.
Gears may be of different sizes, provided the gear ratio is 1:2.
As it has been pointed out here, the design combines the best features enabling the practical application of my design to a modern piston engine with internal'combustion, built for speed.
The sinusoidal piston movement in relation to crank rotation eliminates the higher harmonics completely, releasing extra strength of material for higher revolutions of the crankshaft.
For the same materials used, this design is able to withstand way higher speeds than a typical crankshaft system.

Claims (9)

1. Crankshaft assembly consisting of a crankshaft with one or more cranks, cam sleeve with circular cams, each offset radially by a crankthrow, fitted on the crank together with a cam ring embracing partially one of the said circular cams, with both cam ring and cam sleeve having one conical gear each at opposite ends, the said gears meshing with stationary internal conical gears having twice the amount of teeth each, with double-sided one-piece in-line pistons fitted on the circular cams through pistons centre circular openings, with the hydraulic pressure generated as a result of lubricants introduced between the cam ring and the circular cam, applied between the said cam ring and the cam sleeve for the purpose to ensure the said meshing without any play, with the said pistons fitted into in-line opposite cylinders, the axes of the said cylinders intersect the crankshafts main bearing axis at 90 degrees angles.

2. A crankshaft assembly as defined above in claim 1, where the two sets of conical gears are of different sizes, but the gear ratio remains 1:2 for both sides.

3. A crankshaft system as in claims 1 or 2, wherein the cam ring, consisting of one piece with a conical gear, is changed to a pin engaging into an opening in the side of the neighbouring circular cam, with running fit.

4. A crankshaft system as defined in any one of claims 1 to 3 wherein the piston or pistons are one-sided.

5. A crankshaft system as defined in any one of claims 1 to 4 with only one circular cam, one single or double-sided piston and two sets of gears.

6. A crankshaft system as defined in claims 1, 2, 4 or 5 where the cam sleeve and cam ring form one rigid piece.

7. A crankshaft system as in claim 6, wherein one of the stationary internal conical gears has modified fitting in the crankcase to allow axial movement of the said internal conical gear without rotation and the hydraulic pressure, generated by the lubricant introduced between the said internal conical gear and the crankcase, is moving the said internal conical gear towards the cam sleeve for the purpose to ensure the said meshing without any play.

8. A crankshaft as defined in any one of claims 1 to 7 wherein the system is repeated on the next cranks of the crankshaft.

9. A crankshaft system as defined in any one of claims 1 to 8 wherein the cylinders form V, cross or star configurations.