Machine element or mechanism – Elements – Pitmans and connecting rods
Patent
1986-10-17
1990-03-06
Luong, Vinh T.
Machine element or mechanism
Elements
Pitmans and connecting rods
74579R, 123197AB, G05G 100
Patent
active
049055402
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to fibre reinforced plastic connecting rods for machinery in which reciprocating motion is converted to rotary motion or vice versa.
There are many industrial uses of machines in which reciprocating motion is converted into rotary motion, the best known example being the internal combustion engine. In this type of machine a significant proportion of the energy lost results from the need to overcome the inertia of connecting rods. Connecting rods are used to transfer the reciprocating motion of pistons to rotary motion of a crankshaft. Connecting rods themselves have a motion which is a combination of linear and rotary.
Conventionally connecting rods have been made of metal, and in order to cut down the energy loss considerable effort has been devoted into reducing their weight. Efforts to reduce weight are, of course, complicated by the fact that connecting rods not only have to carry large forces to fulfil their function but have to sustain the effects of inertia forces due to their own weight. Recent advances in the technology of Fibre Reinforced Plastics (FRP) materials have made these materials suitable for use in the manufacture of connecting rods.
Connecting rods conventionally consist of a rod member having at one end, usually referred to as the little end, means for attaching the rod to a piston, and at the other end, commonly referred to as the big end, means for attaching the connecting rod to a crankshaft. To enable the rod to be connected to a crankshaft it is usually formed in two parts, having a cap member attachable to the rod member, the end of the rod and cap each including semi-circular portions which form a complete circle when the two are joined together.
The usual method of joining the rod and cap involves the use of nuts on bolts which pass through bores in the rod end and in the cap. This method is not ideal for connecting rods of FRP material. Drilling of bore holes in FRP material results in undesireable fracture of fibres. Manufacturing techniques for fabricating ends with bores therein in which fibres are not fractured are complicated and expensive. Also in FRP connecting rods with this type of end cap joint the cross-sectional area of the rod in the region of the bores has to be increased in order to withstand operational stresses. The increase can be such as to make such FRP connecting rods unsuitable for use in existing engine designs.
According to the present invention a connecting rod having a little end and a big end includes a Fibre Reinforced Plastic rod member, a cap member, and securing means for securing the rod and cap members together to define the big end, characterised in that the securing means includes a metal member, rigidly attached to the rod member, to which the cap member can be secured.
In one form of the invention the metal member is in the form of a saddle which is integrally united with the rod member by, for example, winding FRP material round appropriately designed saddle structure and round the rod member.
In another form of the invention the metal member and rod are so adapted that the metal member encloses a locally expanded end of the rod member. In this form of the invention the end of a rod member of rectangular section might be locally expanded on two opposite sides in wedge-like fashion and dove-tailed into a wedge-shaped channel in the metal member. Alternatively the end of the rod might be caused to fit into a frusto-pyrramidal or frusto-conical cut-out in the metal member by, for example, injection moulding of thermoplastic material under appropriate conditions of temperature and pressure.
The cap member may be formed from metal, from FRP material, or from a combination of metal and FRP material.
Some embodiments of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, of which:
FIG. 1 is an elevation, partly in section, of a connecting rod according to the invention and including a metal saddle,
FIG. 2 is a plan view, in section along line II--II
REFERENCES:
patent: 2048187 (1936-07-01), Hughes
patent: 2738687 (1956-03-01), Meile
patent: 3815431 (1974-06-01), Alvarez
patent: 4184384 (1980-01-01), Levine
Patents Abstracts of Japan, vol. 7, No. 279 (M-262) (1424) 13 Dec. 1983 and P, A, 58156714 (Shigehiko) 9/17/83.
Patents Abstracts of Japan; vol. 9, No. 128 (M-384)(1851), 6/4/85 and JP, A, 60011713 (Mitsuya) 1/22/85.
Hughes Joseph D. A.
Lee Walter A.
Mitchell Alexander M.
Wootton Alan J.
Luong Vinh T.
The Secretary of State for Trade and Industry in Her Britannic M
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