GB2080484A

GB2080484A - Connecting rods

Info

Publication number: GB2080484A
Application number: GB8023752A
Authority: GB
Original assignee: CARNPAY INVESTMENTS Ltd
Current assignee: CARNPAY INVESTMENTS Ltd
Priority date: 1980-07-21
Filing date: 1980-07-21
Publication date: 1982-02-03

Abstract

An internal combustion engine has a resiliently displaceable piston to conrod connection to absorb initial combustion force and subsequently to release same during a later part of the power stroke. As shown the piston 6 is coupled to a conrod having an open centre part 1 through a gudgeon pin bearing 5 seated on a block 4 urged upwardly by spring 2. The spring absorbs and stores kinetic energy for subsequent release when the combustion pressure reduces. The arrangement enables high compression ratios to be used. Alternative embodiments utilise an elastomeric bush or a gas cylinder in place of a spring. <IMAGE>

Description

SPECIFICATION Improvements relating to internal combustion engines This invention relates to internal combustion engines and provides a piston and connecting rod assembly whereby engine efficiency may be improved by utilising a higher compression ratio without the probability of attendant catastrophic results of detonation or pre-ignition.

According to this invention there is provided an internal combustion engine wherein the piston is coupled with the connecting rod through a small end bearing assembly affording relative displacement between the piston and connecting rod in the longitudinal direction of the latter.

Preferably the displacement is effected by absorption of kinetic energy into potential energy which is stored and subsequently released following ignition of the charge.

With such an arrangement it is possible to construct an engine having a very much higher compression ratio, for example possibly up to 1 5 to 1 in the case of petrol engines without excessively high loadings being imparted to the connecting rod. Preferably the small end bearing floats within the connecting rod in the longitudinal direction of same and is urged towards the end of the rod by a compression spring or leaf spring or like which is thus able to yield when forces from the expanding charge act on the piston.With such an arrangement, the piston is able to move a distance down the bore without movement of the con rod and it will be apparent that the ignition of the charge may occur before top dead centre with the initial force being absorbed by compression of the spring means whilst the crank moves through top dead centre whereby part of the energy from the charge is stored in the spring to be released subsequently. The spring means used will have sufficient force to ensure that deflection does not occur during normal compression but deflects onls after combustion occurs.

Preferably a piston and cylinder assembly is provided forming part of the connecting rod and allowing relative displacement through compression of a gas within the cylinder. The gas pressure within the cylinder is advantageously made adjustable. In a further arrangement a bush of an elastomeric material is interposed between the con rod and crankshaft bearing or small end bearing or both.

Embodiments according to the invention are further described and shown by way of example in the accompanying drawings, wherein: Figure 1 shows a part side view through the upper end of the connecting rod, small end bearing and piston of one embodiment, Figure 2 shows a section through the connecting rod assembly, Figure 3 shows a detail of part of the small end bearing, and Figure 4 shows a section through a second embodiment.

Referring to the drawings, the conrod of an internal combustion engine is formed with an apertured centre portion 1 in which is located a compression spring 2 bearing against the big end cap 3 at one end and against a block 4 at the other end which is arranged to slide within the aperture provided in the conrod. The block 4 may be channeled at its sides to receive the conrod sides.

The block 4 supports the gudgeon pin 5 on which is mounted piston 6. Thus the piston may move relative to the conrod by compression of spring 2 to a maximum extent as indicated in Figure 1. The customary oil feed aperture 7 may be provided coupled to the big end oil ducts as usual.

The arrangement according to the invention allows the use of a very high compression ratio, for example in the range of 12 to 1 5 to 1 and this in conjunction with the spring loading of the connecting rod allows a recoil action so that a very high and fast rise in combustion chamber pressure caused by a high flame rate on pre-ignition allows the piston to initially travel down the bore possibly to a maximum of one third of its stroke without movement of the crank as in customary engines with a solid connecting rod to piston coupling. The resultant kinetic energy which is thus stored in the recoil by the spring following downward movement of the piston is released to the crank pin at an instant which is as near as possible to an angle between rod and crank of 90 degrees.The high compression ratio without the normal attendant knock or pinking due to the recoil action enables a higher BMEP which occurs at a more effective angle between conrod and crank in terms of mechanical advantage. The effect of this is to produce a higher torque which thus permits higher gear ratios with attendant advantages in fuel consumption.

The spring means is arranged to prevent deflection during normal compression and only deflects following combustion.

The arrangement therefore provides for higher thermal efficiency following the use of higher compression ratios, higher mechanical efficiency due to the kinetic energy being applied to the crank at a more optimum angle with the result of higher torque being produced allowing better gear ratios in a motor vehicle to produce better fuel consumption.

The arrangement described utilises a spring means as being possibly the simplest arrangement, but within the context of the invention other means for absorbing the kinetic energy initially and thereafter releasing same during subsequent travel of the crank may be used. For example, a bush of polybutadiene or the like elastomer may be provided at the small end or big end connection and serving to absorb energy through compression.

Figure 4 shows a further arrangement in which a gas cylinder 42 is provided between the conrod 40 and piston 41. The upper end of cylinder 42 is connected to the piston 41 through gudgeon pin 43 with a further piston 44 connected to the conrod 40. Air or other gas present in the cylinder 42 absorbs energy by compression and the nominal static pressure may be varied by connection to a compressed gas source through flexible piping such as nylon conduit.

Claims

1 An internal combustion engine wherein the piston is coupled with the connecting rod through a small end bearing assembly affording relative displacement between the piston and connecting rod in the longitudinal direction of the iatter.

2. An internal combustion engine according to claim 1, wherein the displacement is effected by absorption of kinetic energy into potential energy which is stored and subsequently released following ignition of the charge.

3. An internal combustion engine according to claim 1 or 2, wherein the small end bearing floats within the connecting rod in the longitudinal direction of same and is urged towards the end of the rod by a compression spring.

4. An internal combustion engine according to claim 1 or 2, wherein a bush of an elastomeric material is interposed between the con rod and crankshaft bearing or small end bearing or both.

5. An internal combustion engine according to claim 1 or 2, wherein a piston and cylinder assembly is provided forming part of the connecting rod and allowing relative displacement through compression of a gas within the cylinder.

6. An internal combustion engine according to claim 5, wherein the gas pressure Is adjustable.

7. An internal combustion engine constructed and arranged to function substantially as herein described with reference to the accompanying drawings.