Heavy-duty connections e.g. for axle/suspension systems

Abstract

A vehicle component such as an axle spindle or suspension beam (3) is connected to a tubular vehicle axle (1) by fitting a connector sleeve (2) onto the axle and subjecting the assembly to a crimping operation in which plural depressions (206,2018) are formed by indentation in the connector sleeve and the axle wall at the connection region (11,12) to fix the connector sleeve on the tubular axle. In the described proposals a solid lubricant (4) such as molybdenum disulphide is applied at the connection region between the connector sleeve (2) and axle (1), before crimping. The further vehicle component (3) is then connected to the connector sleeve (2) by welding.

Claims

1. A method of connecting an inner metal component, which is a tubular vehicle axle or suspension crossbrace having a wall with an outer connection surface, to an outer metal component, which comprises a tube or part-tube which fits around or onto the outer connection surface of the inner component and has a wall with an outer connection surface to complement the outer connection surface of the inner component, the method comprising: fitting the inner and outer components together with said walls complementing; wherein an edge of the outer component overlies the outward surface of the inner component and has an inwardly-directed edge surface portion that is angled and spaced away from the outward surface of the inner component to define an open convergent groove therebetween; forming one or more depressions in both said walls by indentation, providing a mating engagement between the inner and outer components at the aligned depressions thereof, to connect them together by mechanical interlock; providing a solid lubricant between the inner and outer components at a connection region where the one or more depressions are formed, so that the lubricant is present between the indented wall portions of the components; and providing a seal along the open convergent groove, thereby forming a boundary to retain the lubricant at the connection region and/or to keep contaminants out of the connection region.

2. The method of claim 1 in which the solid lubricant is selected from the group consisting of molybdenum disulphide, graphite, boron nitride (hBN), and tungsten disulphide.

3. The method of claim 1 in which the lubricant is applied preliminarily to the connection region in a fluid form or carrier, selected from the group consisting of a paste, grease, and spray, and is applied to the outer surface of the inner component, or to the inner surface of the outer component at the connection region, or to both said surfaces.

4. The method of claim 1 in which plural said depressions are formed in an array distributed around the inner and outer components.

5. The method of claim 1 wherein the one or more depressions are inwardly directed, so that the outer surface of the outer component is indented and the inner surf ace of the inner component-projects inwardly.

6. The method of claim 1 further comprising subsequently attaching a further component to the outer component.

7. A connected assembly comprising an inner component and an outer component connected thereto, the assembly obtained or obtainable by the method of claim 1, and having said one or more depressions and the lubricant present at the interface between the inner and outer components at said one or more depressions.

8. The method of claim 6 wherein the method of subsequently attaching the further component to the outer component comprises welding.

9. The method of claim 1 wherein the inwardly-directed edge surface portion is angled away from the outward surface of the inner component as a chamfer or radius.

10. A method of connecting a vehicle component to a tubular vehicle axle, comprising: fitting a connector sleeve onto or around said axle, and providing solid lubricant interposed between the connector sleeve and axle at a connection region; wherein an edge of the connector sleeve overlies the outward surface of the axle and has an inwardly-directed edge surface portion that is angled and spaced away from the outward surface of the axle to define a convergent groove therebetween; subjecting the resulting assembly to a crimping operation to form plural depressions in the connector sleeve and in the wall of the axle at the connection region, to fix the connector sleeve on the tubular axle; and providing a seal along the open convergent groove of the connector sleeve, thereby forming a boundary to retain the lubricant at the connection region and/or to keep contaminants out of the connection region.

11. The method of claim 10 further comprising attaching a further vehicle component selected from the group consisting of a suspension component, a brake assembly, and an axle spindle, to the connector sleeve by means comprising welding.

12. An axle assembly obtainable by the method of claim 10, comprising the axle, the crimped-on connector sleeve with the solid lubricant present between the connector sleeve and axle at the connection region.

13. The assembly of claim 12 further comprising a suspension beam attached to the connector sleeve by welding.

14. The assembly of claim 12 in which the solid lubricant further comprises molybdenum disulphide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An example of the invention is now described, with reference to the accompanying drawings in which:

(2) FIG. 1 is a perspective view of a heavy-duty vehicle axle (truck axle) fitted with connector sleeves in accordance with our proposals;

(3) FIG. 2 shows the axle tube before fitting the sleeves;

(4) FIGS. 3 and 4 are end views of the axle fitted with a sleeve, respectively before and after a crimping operation;

(5) FIG. 5 is a perspective view showing part of a heavy-duty vehicle (truck) suspension assembly incorporating an axle embodying our proposals, and showing a transverse cross-section at a connection region;

(6) FIG. 6 is an enlarged view of a similar cross-section at a connection region;

(7) FIG. 7 is a longitudinal axial cross-section at a connection region, showing edge shaping of the connector sleeve, and

(8) FIG. 8 shows detail of a seal at the connector sleeve edge.

DETAILED DESCRIPTION OF EMBODIMENTS

(9) FIG. 1 shows a tubular steel truck axle 1 fitted with four connector sleeves 2. The connector sleeves 2 at the extreme ends of the axle tube 1 are for connection of axle spindles (not shown). Spaced in from the ends of the tube are two further connector sleeves 2 which are for welded connection to respective suspension components such as arms, links, springs or beam members through which the axle is to be connected to the vehicle frame, usually through pivots at frame hangers or the like, to constitute a suspension system. These general features of a heavy-duty suspension assembly and suspension system are well known.

(10) The axle tube 1 and connector sleeves 2 in these embodiments constitute embodiments of the inner and outer components in the general terminology of the present disclosure.

(11) FIG. 2 shows the axle tube 1 before fitting of the sleeves, and indicates the connection regions, specifically first and second spindle connection regions 12 at the ends of a tube and first and second beam connection regions 11 spaced inwardly therefrom. A longer central region 10 of the axle extends between these.

(12) FIG. 2 shows (by shading) a lubricant composition 4, in the form of an anti-fretting paste containing a molybdenum disulphide solid lubricant, applied to the axle tube outer surface 101 at the connection regions 11,12. The outer tube surface may be prepared for cleanliness and good adhesion, especially freedom from small particles which might be abrasive e.g. by shot blasting, cleaning and the like. Lubricant paste may be applied by brushing, or lubricant may be applied by spray in a more fluid formulation. These lubricant types offer very low friction with high pressure resistance and high temperature resistance, up to about 800° C. The skilled person will be aware of other molybdenum disulphide-containing compositions, and of other types of solid lubricant compositions which may be used instead.

(13) The steel connector sleeves 2 are fitted at the connection regions 11,12 by a crimping process, generally as described in WO2012/044802. The sleeve is fitted around the axle tube, with a slight radial clearance so that the applied lubricant is not significantly displaced. In typical examples the axle tube 1 might be from 100-150 mm in external diameter, and from 5-10 mm in wall thickness. The connector sleeves 2 might be e.g. from 5-10 mm in thickness. An initial fitting clearance between the ID of the sleeve and the OD of the tube may be e.g. from 1-5 mm radially i.e. considered at a concentric situation. The connector sleeves may be continuous sleeves or welded sleeves; a weld seam 21 is indicated in FIG. 3.

(14) As described in WO2012/044802 this pre-assembly is subject to a crimping and swaging process in an appropriate apparatus with a die set selected to indent the component walls and produce an array of circumferentially- and longitudinally-localised indentations or depressions around the axle tube assembly at each sleeve, as shown in FIG. 1. FIG. 4 shows, by an end view, the substantial indentation of the walls of both components, and the elimination of the initial clearance between the components by the swaging effect.

(15) During this deformation the anti-fretting paste 4 operates to reduce friction and potential fretting between the inner and outer components during the crimping operation. The material of the sleeves 2 is a lower carbon steel than the axle tube 1 and undergoes more plastic deformation during the crimping operation, so that after the elastic recovery of the components, the concave outer surfaces of the axle tube depressions 208 are urged forcibly outwardly into contact with the convex inner surfaces of the respective sleeve depressions 206 (see FIG. 6), creating an entirely rigid connection between the sleeve 2 and the tube 1. The illustrated embodiment has eight depressions distributed around the tube. The number is not strictly limited and may be e.g. from 2 to 10, and can be selected in accordance with the size and shape of the components to provide the necessary degree of security.

(16) FIG. 5 shows how the axle tube 1 fitted with the connector sleeves 2 is connected to a suspension component, in this case a trailing arm beam 3, to form a suspension assembly 214 at one side of a suspension system. In this embodiment the beam 3 constitutes the “further component”, in the general terminology used herein.

(17) The illustrated beam 3 has a hollow fabricated form. A channel-form member constitutes the top and side walls 266 of the beam, and a bottom plate 263 welded along the bottom edges of the side walls 266 completes the structure. The beam has a front end 220 with a bushing tube 242 for a pivot connection to the frame, and a rear end 226 projecting behind the axle location and where an air spring may be mounted. The two side walls 266 have aligned circular openings 209 sized and spaced to receive a single connector sleeve 2 of the axle assembly. The assembly is completed by forming circular welds CW around the opening between the sleeve 2 and each side wall 266 of the beam 3. The convenience of a welded-only connection is achieved but without welding directly onto the axle. By avoiding welding directly to the axle, local stress risers can be avoided or reduced and durability and lifetime enhanced. Moreover the selected solid lubricant in the connection regions between sleeve and axle can withstand the conditions at that location during the nearby welding, which typically might rise to about 500° C.

(18) Since a film of the lubricant is then maintained between the contacting surfaces of the axle tube 1 and sleeve 2, fretting and corrosion are inhibited at these areas even under conditions of use including vibration, and an improvement in average lifetime can be expected. The crimped contact is sufficiently tight and uniform over the joint to keep out water and protect the lubricated area in general operation.

(19) FIG. 7 shows a preferred structure at the edges 22 of the connector sleeve 2. Here one sleeve edge 22 overlies a corresponding edge 30 at the end of the axle tube 1, the other sleeve edge 22 overlies the outer surface 101 of the axle tube which extends out beyond the sleeve 2. At each edge 22 the original “square” inner edge corner has been machined back as an enlarged radius or chamfer, forming an inwardly-directed edge surface portion 23 angled and spaced away from the outer axle surface 101 and defining a convergent groove 5 between them. The extremity of the sleeve 2, which might tend to make frictional or fretting engagements with the axle surface 101 during deformation under load, then presents a rounded and gently angled surface to minimize such potential for frictional damage.

(20) Additionally, the groove 5 can be used to help form a precautionary outer seal around the lubricant-containing connection region. FIG. 8 shows, in a fragmentary cross-sectional view, how a sealant such as a polyurethane or silicone sealant can be applied all around the edge 22 in the groove 5 to form a seal bead 6. The overhang of the sleeve edge 22, over the groove 5, helps to protect the seal bead 6 against damage during subsequent use of the axle.

(21) It will be understood that not only suspension beams but other kinds of further component, such as a brake system element or axle spindle, can be secured to the axle in an analogous way.