GB2123923A

GB2123923A - Flbre-reinforced plastics connecting rod

Info

Publication number: GB2123923A
Application number: GB08315147A
Authority: GB
Inventors: Thomas Fischer; Bernd Bongers
Original assignee: Messerschmitt Bolkow Blohm AG
Current assignee: Airbus Defence and Space GmbH
Priority date: 1982-07-07
Filing date: 1983-06-02
Publication date: 1984-02-08
Also published as: FR2529973B1; GB2123923B; DE3225325C1; GB8315147D0; FR2529973A1

Abstract

A connecting rod made of fibre- reinforced plastics material and having at one end 2 a closed cylindrical bearing and the other end 3, a split cylindrical bearing comprises a closed loop 4 of reinforcement extending in a bight around the closed bearing cylinder 6 in the longitudinal direction along the rod to bights 4.1 around bolt 5. <IMAGE>

Description

SPECIFICATION Connecting rod made of fibre-reinforced plastics material This invention concerns a connecting rod made of fibre-reinforced plastics material, one rod end of which, for example for a piston pin or gudgeon pin, is designed as a closed cylindrical bearing and the other end of which, for example for a crankpin, is designed as a split cylindrical bearing, consisting of an open half-shell-shaped head part with a complementary half-shell-shaped bearing cover, in which unidirectional fibre strands are combined into a loop forming a bight around the closed cylindrical bearing and which extends longitudinally of the connecting rod and to the bands or chords of which the bearing cover is connected.

In such a connecting rod, the crankpin bearing is, as is known, split for fitting reasons. The embodiment known from German Offenlegungsschrift No.

30 04 575 is provided with a metal jacket around a plastics core, in comparison with a corresponding fully-metal structure, so as to achieve a considerably lower mass and this leads, particularly where used in high-speed piston engines, to quiet operation and improved efficiency. Among such criteria there exists, of course, the endeavour to dispense with any metal parts. The mere elimination of the metal jacket of the known connecting rod, of course, inter alia no longer guarantees the necessary strength to withstand practical compressive and tensile forces. The remaining fibre loop, in itself only capable of withstanding tensile loading, would buckle under compressive loading.Moreover, such a composite structure, utilising a metal jacket inter alia as defining the outer shape of the fibre loop, of two materials of different modulii of elasticity has, under loading of the connecting rod, the result that the stiffer fibre material is the one that is predominantly loaded, i.e.

the supporting metal jacket is not fully loaded.

The problem underlying the invention is to make it possible, in the case of a connecting rod of the kind referred to at the introduction hereof, substantially to dispense with metal parts without there being any diminution in the strength of the connecting rod.

To solve this problem, the present invention provides a connecting rod as aforesaid characterised in that the loop is in the form of an endless noose and extends over the length of the connecting rod and about a bolt and on the other hand extends around the closed cylindrical bearing on both sides thereof, being spread apart at its two regions towards the bolt by a bearing bracket for overlapping uniting thereof with the bearing cover which is connected by way of the bolt, the space between the closed bearing cylinder and the bearing bracket being filled by a pressure bar.

Accordingly the invention is not confined to a combination of a fibre loop with a bar which, by reason of its presence between the two bearings of the connecting rod, extensively ensures the pressure absorption capacity thereof. On the contrary, in the case of the composite structure involving the fibre loop and the pressure bar, despite dispensing with a partition of the loop belts, connection of the bearing cover without flanges, i.e. without loop curvatures, is made possible. Otherwise, for this, because of the requirement for flat flange surfaces of the open rod end, a supporting sheathing would be indispensable. Insofar as supporting means become necessary, use can be made of fibre composite component parts of the simplest shape.Appropriate further developments (as specified in the sub-claims appended hereto) and further details of the invention, will be described further by way of example, with reference to the accompanying drawings, in which Figure lisa front view illustrating a preferred embodiment of the connecting rod of the invention, made of fibre composite material, this embodiment being split at one of the two rod ends; Figure 2 is a side view of the connectin rod of Figure 1; Figure 3 is a perspective view, to a smaller scale, illustrating the basic body of the connecting rod of Figures 1 and 2; and Figure 4 is a fragmentary sectional front view, to a larger scale, through the split end of the connecting rod of Figures 1 to 3.

For use, for example, as a connecting member between a linearly-moving part (such as a piston, not shown) of a crank assembly and a crankshaft, the depicted connecting rod consists substantially of a rod shaft 1 having rod ends 2 and 3, designed as cylindrical bearings, on the one hand for a piston pin or gudgeon pin (not shown) and on the other hand for a crankpin (also not shown). For fitting on the crankpin, the respective rod end 3 is split, being composed of an open half-shell-shaped rod head part 3.1 and a complementary half-shell-shaped bearing cover 3.2.In order to achieve, for this split configuration of the connecting rod, in particular for the main or shaft part thereof, a structure consisting of composite fibre material, such as carbon fibre in a synthetic resin matrix, whilst dispensing with metal and without involving diminution in strength, used for the basic body of the connecting rod is an endless fibre loop 4 of unidirectional fibre strands in the form of a noose which is folded along its length so as to extend at both ends around a bolt 5 and which on the other hand extends as a bight which embraces the closed bearing cylinder 6 on both sides thereof; the selected noose form is illustrated more particularly in Figure 3.The open rod end part 3.1 is formed, along with appropriate spreadingapart of the two loop ends 4.1 in the region of the bolt 5, by a saddle-like bearing bracket 7 consisting of fibre strands in an orientation crosswise to the direction of the extent of the bracket, more particularly +45 orientation. Consequently, the bearing bracket 7, being in self-substance connection or integral connection with the individual bolt-sided loop ends 4.1, ensures necessary thrust or shear strength and stiffness as well as the necessary internal bearing strength in the same way as covering layers 8 united oppositely at the respective outer end face with the loop ends 4.1 and consisting of fibre strands in +45 orientation.In this connection, inserted between the two strands of the loop ends 4.1, towards the bolt 5, is a respective distancekeeping filling piece 9 (Figure 2), which the bolt 5 traverses like the bearing bracket 7 and the covering layers 8. Moreover, the space between the closed bearing cylinder 6 and the bearing bracket 7 is filled with a pressure bar 10 which has a structure consisting of unidirectional fibre strands with an orientation at least in the direction of the extent of the rod, and thus ensures the necessary compressive strength and stiffness of the connecting rod.In conjunction with the two associated loop ends 4.2 and the pressure bar 10, the bearing cylinder 6 consists, for example as a coil body, of fibre strands preferably in a 0 /90 orientation with regard to the longitudinal axis of the bearing, if necessary, additionally a metal bearing brass 6.1 is provided. To increase the thrust or shear strength of the entire fibre structure of the conecting rod, finally, as shown in Figure 2, provided at the loop end faces are covering layers 11 in each case consisting of fibre strands, in +45 orientation, which subdivide the pressure bar 10 in the longitudinal axis of the bearing, It is self-evident that for all crosswiseorientated fibre material appropriate fabric or lay-up are usable.

Finally, the bearing cover 3.2 is detachably united with the bearing bracket 7, by way of the bolt 5; because of the overlapped arrangement thereof a lining 7.1 is provided on the bearing surface of the bearing bracket of thickness in accordance with the thickness of the butt edges of the bearing cover 3.2 attached thereto. In this kind of cover connection, using a bolt 5 which is arranged in a yoke-like manner, there is no restriction in the choice of material for the bearing cover 3.2. In the case of a plastics or even light-metal version, additionally a split metal bearing brass 12 may be provided, and this may be moulded-in or bonded-in.

As is additionally illustrated by Figure 4, by providing taper fitting sleeves 13 one can achieve, by mere tightening of nut 5.1 on the bolt 5, the desired positioning of the bearing cover 3.2 relative to the bearing bracket 7 or the lining 7.1 thereof with play-free (possibly pre-stressed) seatin on the crankpin (not shown). Also a bipartition of the bolt is conceivable; the two halves of the bolt can then, for example, be stud bolts engaging into threaded blind holes in the bearing cover. Closure or sealing of the hole edges can be achieved by elastic shims or washers 14 between the taper fitting sleeves 13 and the covering layers 8, without hindering the aforesaid positioning procedure.

Claims

1. A connecting rod made of fibre-reinforced plastics material, the one rod end of which, for example for a piston pin or gudgeon pin, is designed as a closed cylindrical bearing and the other rod end of which, for example for a crankpin, is designed as a split cylindrical bearing, consisting of an open half-shell-shaped head part with a complementary half-shell-shaped bearing cover, in which unidirectional fibre strands are combined into a loop forming a bight around the closed cylindrical bearing and which extends longitudinally of the connecting rod, and to the bands or chords of which the bearing cover is connected, characterised in that the loop is in the form of an endless noose and extends over the length of the connecting rod and about a bolt and on the other hand extends around the closed cylindrical bearing on both sides thereof, being spread apart at its two regions towards the bolt by a bearing bracket fo overlapping uniting thereof with the bearing cover which is connected by way of the bolt, the space between the closed bearing cylinder and the bearing bracket being filled by a pressure bar.

2. A connecting rod as claimed in claim 1, characterised in that a distance-maintaining filling piece is inserted between the two strands of the individual loop ends of the noose, towards the bolt.

3. A connecting rod as claimed in claim 1 or 2, characterised in that the said loop ends are united at the respective outer end faces with a covering layer of fibre strands in crosswise orientation.

4. A connecting rod as claimed in claim 1, characterised in that the noose is united at the loop end faces with covering layers subdividing the pressure bar in the longitudinal bearing direction and consisting of fibre strands in crosswise orientation.

5. A connecting rod as claimed in claim 1, characterised in that the closed bearing cylinder is built up from fibre strands in crosswise orientation, more particularly 0 190 orientation with regard to the bearing longitudinal axis.

6. A connecting rod as claimed in claim 1, characterised in that the bearing bracket is built up from fibre strands in an orientation which is crosswise with regard to the direction of the extent of the bracket, more particularly j45 orientation.

7. A connecting rod as claimed in claim 1 or 6, characterised in that the bearing bracket is provided, on the bearing surface, with a liner at least of a thickness corresponding to the thickness of the butt edges of the bearing cover attached thereto.

8. A connecting rod as claimed in claim 1,4 or 5, characterised in that the pressure bar or the individual or single layer thereof is built up at least from fibre strands with an orientation in the direction of the extent of the rod.

9. A connecting rod substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.