GB2082675A

GB2082675A - Crankshaft and piston arrangement in an internal combustion engine

Info

Publication number: GB2082675A
Application number: GB8123279A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-25
Filing date: 1981-07-28
Publication date: 1982-03-10
Also published as: DE3131060A1; SE8104552L; IT8123624A0; IT1195276B; JPS5773801A

Abstract

The crankshaft axis 34 is offset from the cylinder axis 24 so that the torque at the beginning of the power stroke is increased. <IMAGE>

Description

SPECIFICATION Crankshaft and piston connection for an internal combustion engine technical field The field of this invention relates to crank mechanisms, and more particularly to the use of a crank mechanism in conjunction with a piston driven internal combustion engine.

Background of the prior art Internal combustion engines are well known.

The general form of internal combustion engine comprises a block within which is generally formed a plurality of spaced-apart cylindrical openings. Within each cylindrical opening is located a piston. Each piston is reciprocally movable in a direction along the longitudinal center axis of its cylindrical opening.

Each piston is connected to a crankshaft. The connection between each connecting rod and the crankshaft is about a pivot axis which is spaced from the rotation axis of the crankshaft. The longitudinal center axis of each cylinder passes through the rotation axis of the crankshaft. In general, the power transmitted to the crankshaft is in the form of crank torque generated by the reciprocating pistons. This crank torque is proportional to the magnitude of the tangential force vector acting on the radius of the crankshaft which, in essence, is simply the rotative effort applied to the crankshaft.

In more descriptive terms, the initiation of the power stroke (burning of the fuel within the cylinder) starts the movement of the piston in a downward direction. Within a conventional internal combustion engine, the axial center line of the connecting rod passes directly through the rotation axis of the crankshaft. Inertia causes the crankshaft to rotate and as it rotates, the axial center line of the connecting rod becomes spaced from the rotation axis of the crankshaft. This spacing will continue to increase until it will become greatest when a line connecting the pivot connection of the connecting rod to the crankshaft and the rotation axis of the crankshaft is perpendicular to the longitudinal center axis of the cylinder.

It is well known that power, or torque, occurs only when there is force times distance. The force being applied to the piston is transformed into torque when there is a spacing of the pivot connection of the connecting rod to the crankshaft from the rotational axis of the crankshaft. If no spacing exists, which is what occurs at the beginning of the power stroke within the conventional internal combustion engine, there is no output torque. This is due to the fact that at this particular instant, the direction of the force of the piston is directly in-line with the rotation axis of the crankshaft. The force at this particular instance is functioning only to attempt to bend the connecting rod.

As the crankshaft continues to turn due to inertia, a slight spacing occurs between the pivot axis connection of the connecting rod to the crankshaft and the rotation axis of the crankshaft.

As previously mentioned, this pivot axis spacing continues to increase for the next ninety degrees of movement of the crankshaft.

Although all known internal combustion engines have been constructed in precisely the same manner, by altering the arrangement between the crankshaft and the longitudinal center axis of the firing cylinder, a significant increase in the efficiency will occur.

Brief summary of the invention The structure of this invention is to be applied to the basic conventional arrangement in the construction of an internal combustion engine.

The internal combustion engine includes at least one firing cylinder, which takes the form of a cylindrically shaped opening formed within an engine block. This cylindrical opening has a longitudinal center axis. A connecting rod is pivotally connected to the piston and also pivotally connected through a pivot axis to a crankshaft.

The pivot axis is spaced from the rotational axis of the crankshaft. The rotational axis of the crankshaft is offset a predetermined distance from the longitudinal center axis of the the cylinder opening. At the very beginning of the power stroke of the piston, torque is immediately applied to the crankshaft, since there is a spacing between the rotation axis of the crankshaft and the longitudinal center axis of the cylinder opening.

The primary objective of this invention is to construct an internal combustion engine which is capable of achieving a substantially greater output torque than was possible with conventional types of internal combustion engines.

Another objective of this invention is to achieve a significantly greater output torque with only minor modification of internal combustion engine structure.

Brief Description of the Drawing Figure 1 is a perspective view of a typical internal combustion engine within which the structure of the present invention is embodied: Figure 2 is a cross-sectional view through the engine of Figure 1 taken along line 2-2 depicting the novel structure of this invention between the piston and a crank shaft; and Figure 3 is a view similar to Figure 2, but showing the piston at the instant of initiation of the power stroke.

Detailed Description of the Shown Embodiment Referring particularly to the drawing, there is shown in Figure 1, the internal combustion engine 10 which is constructed of a conventional engine block 12 which is closed at its upper end by a head 14. Within the block 12 are formed a plurality of cylinder openings 1 8 with there only being a single said cylinder opening 1 8 being shown within Figures 2 and 3. Within each cylinder opening 1 8 there is reciprocally mounted a piston 1 6. This piston 1 6 is to be movable only in a direction coinciding with the longitudinal center axis 24 of the cylinder 18.

The piston 1 6 has attached thereto a wrist pin 20. The wrist pin 20 is connected to a connecting rod 26. The connecting rod 26 is to be pivotal with respect to the piston 1 6 along a pivoting axis 22 which comprises the center point of the wrist pin 20.

The free, or outer end, of the connecting rod 26 is attached to a pin 28 which in turn is pivotally mounted about a pivot axis 30 to a crankshaft 32.

The crankshaft 32 is rotatably mounted about a rotation axis 34 within the engine block 12. An oil pan 38 functions to totally enclose the crankshaft 32 with respect to the engine block 12.

A line 36 is conducted through the rotation axis 34 and is located parallel to the longitudinal center axis 24 of the cylinder 1 8. It is to be noted that the line 36 is spaced, or offset, a certain distance from the axis 24. The amount of this offset is deemed to be a matter of choice. But, it has been found that a preferable offset is so that there is an approximately a thirty degree angle formed between line 36 and a line 40. Line 40 is connected between axis 30 and axis 34.

The operation of the engine constructed in accordance with the present invention is as follows: As the piston 1 6 approaches the top dead center position, which is shown within Figure 2, the burning of the fuel and air mixture within the upper end of the cylinder opening 1 8 occurs which results in the power stroke of the piston 1 6. The crankshaft 32 has pivoted to the position shown within Figure 3, which puts the axial center line of the connecting rod 26 coinciding with the axis 24.

At this particular point, there is a distance, or space, (like one inch) between the axis 30 and the line 36. Therefore, there is an immediate significant torque created at the very beginning of the power stroke of the piston 16. This torque continues to increase until line 40 becomes perpendicular to line 36. It is to be noted that torque continues through the next ninety degrees of rotation of the crankshaft 32, which would end the power stroke of the piston 16.

Calculations were made with a piston diameter of 3.736 inches. Assuming a force being applied to the top of the piston 26 of 300 pounds per square inch, there would result in a load of 3,289 pounds being transmitted to the piston 1 6. If, as in a prior art engine, the pivot axis 34 coincided with the axis 24, there would occur only a small value of torque near top dead center of the piston (such as about 500 inch pounds). However, at the thirty degree position shown within Figure 3, within the structure of the present invention, which is also < very near top dead center, the value of torque is 2,861 inch pounds. These calculations are not precise, but are accurate enough to compare the structural difference between the present invention and the prior art. This results in an additional power output of approximately twenty five percent using the structure of the present invention instead of the piston, cylinder arrangement of the conventional prior art. The angle of thirty degrees between line 40 and line 36 was arbitrarily picked and very well may not be the optimum angle. Another advantage of the invention is with the load on the crankshaft 34 reduced, the physical weight of the crankshaft may be also reduced.

Claims

1. A crankshaft and piston connection for an internal combustion engine having at least one fuel firing cylinder, a reciprocating piston mounted within said cylinder, said piston to be movable in a direction along the longitudinal center axis of said cylinder, comprising a connecting rod, one end of said connecting rod being pivotally connected to said piston, a crank shaft rotatable about a rotation axis, said connecting rod being pivotally connected to said crankshaft at a pivot axis, said pivot axis being spaced from said rotation axis, wherein said rotation axis is offset to predeterminely space said rotation axis from said longitudinal center axis of said cylinder, whereby at the initiation of the power stroke of said cylinder an initial significant value of torque is imparted to said crankshaft by said connecting rod.

2. A crankshaft and piston connection as claimed in Claim 1 wherein: at the point of initiation of the power stroke of said cylinder a line connecting said rotation axis and said pivot axis being located substantially at thirty degrees in respect to said longitudinal center axis of said cylinder.

3. A crankshaft and piston connection substantially as herein described with reference to and as illustrated in the accompanying drawings.