GB2170880A - Fibre reinforced plastic connecting rod - Google Patents

Abstract

A connecting rod has a rod member 10 formed from Fibre Reinforced Plastic (FRP) material. The rod member 10 is connected to an end cap 21 (which might also be of FRP material) by means of roll pins 25 which pass through holes 20 in legs 19 of the rod member 10 and through holes (24) in legs 23 of the end cap 21. <IMAGE>

Description

SPECIFICATION Fibre reinforced plastic connecting rod 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 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.

Methods for joining the rod and cap, which have been developed for conventional metal connecting rods, are frequently not applicable to FRP connecting rods due to the differing characteristics of FRP and metal materials.

According to the present invention a connecting rod has a Fibre Reinforced Plastic rod member and a cap member, the rod member and cap member being connected by means of two roll pins each of which passes through three legs two of which extend from one member and lie one on each side of the third which extends from the other member.

Preferably the two legs extend from the rod member. The cap member may be made of metal or of FRP material.

One embodiment of the invention will now be described by way of example only, with reference to the accompanying diagrammatic drawings, of which: Figure 1 is a side elevation of a connecting rod according to the invention, Figure 2 is a section along line II to II of Fig. 1, and Figure 3 is a end elevation of the connecting rod.

A connecting rod has a rod member shown generally at 10 and which includes a central FRP moulding 11 of section (Fig. 2). A FRP overlay 12 having uni-directional fibres encloses the central moulding 11, the overlay 12 and central moulding 11 being shaped to have a first end 13 to which a tubular insert 14 is secured by a bonded FRP overwrap 15, and a second end 14 having therein a semi-circular channel 16 bounded by arms 17. Each arm 17 has a channel 18 bounded by legs 19 at each extremity (Fig. 3). Each leg 19 has a hole 20 the holes 20 having a common axis.

An end cap 21 has a semi-circular channel 22 of substantially identical diameter to the semi-circular channel 16 of the rod member 10. From each side of the end cap 21 extends a leg 23 having a hole 24 therein.

In use the tubular insert 14 is attached to a piston (not shown) by means, for example, of a gudgeon pin. The semi-circular section 16 of the rod member 10 is positioned over a bearing member 26 positioned on a bearing surface of a crankshaft and the cap member is then positioned also over the bearing shell 26 with its legs 23 lying between legs 19 of the rod member 10 such that the holes 20, 24 are co-axial, and roll pins 25 are inserted through the holes.

Those skilled in the art will realise that many other embodiments of the invention are possible. Also those skilled in the art will be aware of the properties of FRP materials suitable for use with the invention, so these materials will not be discussed herein.

A connecting rod having a Fibre Reinforced Plastic rod member and a cap member, the rod member and cap member being connected by means of two roll pins each of which passes through three legs two of which extend from one member and lie one on each side of the third which extends from the other member.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (1)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   SPECIFICATION Fibre reinforced plastic connecting rod 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 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.

   Methods for joining the rod and cap, which have been developed for conventional metal connecting rods, are frequently not applicable to FRP connecting rods due to the differing characteristics of FRP and metal materials.

   According to the present invention a connecting rod has a Fibre Reinforced Plastic rod member and a cap member, the rod member and cap member being connected by means of two roll pins each of which passes through three legs two of which extend from one member and lie one on each side of the third which extends from the other member.

   Preferably the two legs extend from the rod member. The cap member may be made of metal or of FRP material.

   One embodiment of the invention will now be described by way of example only, with reference to the accompanying diagrammatic drawings, of which: Figure 1 is a side elevation of a connecting rod according to the invention, Figure 2 is a section along line II to II of Fig. 1, and Figure 3 is a end elevation of the connecting rod.

   A connecting rod has a rod member shown generally at 10 and which includes a central FRP moulding 11 of section (Fig. 2). A FRP overlay 12 having uni-directional fibres encloses the central moulding 11, the overlay 12 and central moulding 11 being shaped to have a first end 13 to which a tubular insert 14 is secured by a bonded FRP overwrap 15, and a second end 14 having therein a semi-circular channel 16 bounded by arms 17. Each arm 17 has a channel 18 bounded by legs 19 at each extremity (Fig. 3). Each leg 19 has a hole 20 the holes 20 having a common axis.

   An end cap 21 has a semi-circular channel 22 of substantially identical diameter to the semi-circular channel 16 of the rod member 10. From each side of the end cap 21 extends a leg 23 having a hole 24 therein.

   In use the tubular insert 14 is attached to a piston (not shown) by means, for example, of a gudgeon pin. The semi-circular section 16 of the rod member 10 is positioned over a bearing member 26 positioned on a bearing surface of a crankshaft and the cap member is then positioned also over the bearing shell 26 with its legs 23 lying between legs 19 of the rod member 10 such that the holes 20, 24 are co-axial, and roll pins 25 are inserted through the holes.

   Those skilled in the art will realise that many other embodiments of the invention are possible. Also those skilled in the art will be aware of the properties of FRP materials suitable for use with the invention, so these materials will not be discussed herein.

   A connecting rod having a Fibre Reinforced Plastic rod member and a cap member, the rod member and cap member being connected by means of two roll pins each of which passes through three legs two of which extend from one member and lie one on each side of the third which extends from the other member.