JOINT BETWEEN TWO COMPONENTS

Abstract: A joint (12) between an at least hollow ended, generally cylindrical first component (14) and a second component (16). The first component has a first end portion (18) terminating in a first free end region (20), a second end portion (22) terminating in a second free end region, and a mid portion (24) extending between the first and second end portions. The mid portion (24) has a first predetermined external diameter and the first end portion (18) has an external diameter which increases gradually from the first predetermined external diameter to a second predetermined external diameter at the first free end region (20). The first end portion is adapted to be pushed onto a tapered pin (26) extending from the second component (16) to a joined position. To ensure transmission of rotational forces, in the joined position the first free end region (20) of the first component extends into a generally ring-shaped socket (28) in the second component, with the socket having at least one substantially planar circumferentially and axially extending surface (30) against which a corresponding planar surface (32) extending axially from the free end (34) of the first free end region (20) abuts.

Description: TITLE: Joint between two components TECHNICAL FIELD: The present invention relates to a joint between an at least hollow ended, generally cylindrical first component and a second component according to the preamble of claim 1. BACKGROUND OF THE INVENTION: In order to permit rotational transmission between a shaft- like first component and a second component, it is known to provide the components with interengaging splines or to key the components together. Alternatively, the shaft-like component may be provided with a flattened circumferential portion which cooperates with a flat surface on the second component. It is also known to press fit a hollow shaft-like first component onto a tapered pin on a second component. Thus, as the first component is pressed onto the second component, the diameter of the first component is forced to increase, resulting in a decrease of the wall thickness of the first component. SUMMARY OF THE INVENTION: It is an object of the present invention to provide an improved joint between an at least hollow ended, generally cylindrical first component and a second component, which joint is suitable for transmitting rotational and bending forces. This object is achieved by a joint according to claim 1 It is a further object to provide a joint between a resilient hollow ended, generally cylindrical first component and a stiffer second component, which joint CONFIRMATION component and a stiffer second component, which joint allows for a progressive transition of rotational stiffness between said components. This object is achieved by a joint according to claim 2. Further advantageous embodiments of the present invention are detailed in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS: The invention will be described in the following by way of example only and with reference to the attached drawings, in which Fig. 1 is a schematic perspective view of a suspension assembly for a vehicle, the assembly employing a pair of joints according to the present invention; Fig. 2 is a schematic perspective view of two components of the suspension assembly of Fig. 1 which are to be joined by a joint according to the present invention, and Fig. 3 is a partial sectional view through the two components of Fig. 2 in a joined condition. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS: In Fig. 1, reference numeral 10 generally denotes a suspension assembly for a vehicle, the assembly incorporating a pair of joints generally denoted by 12 according to the present invention. The joints 12 unite an at least hollow ended, generally cylindrical first component 14 and a second component 16. In the illustrated example, the first component 14 is a generally omega- shaped, hollow composite spring, whilst the second component 16 is a suspension arm. With particular reference to Figs. 2 and 3, the first component 14 comprises a first end portion 18 terminating in a first free end region 20, a second end portion 22 (Fig. 1) terminating in a second free end region, and a mid portion 24 extending between the first and second end portions. The mid portion 24 of the first component 14 presents a first predetermined external diameter. As is clearly illustrated in Fig. 3, the first end portion 18 of the first component presents an external diameter which increases gradually from the first predetermined external diameter to a second predetermined external diameter at the first free end region. In this respect, the expression "increases gradually" implies that the outer surface of the first component forms an angle which is no more than 60 degrees, preferably no more than 45 degrees with respect to the longitudinal axis of the first component. The first end portion 18 of the first component 14 is adapted to be pushed onto a preferably hollow tapered pin 26 extending from the second component 16 until the joined position as illustrated in Fig. 3 is reached. In accordance with the present invention, in the joined position the first free end region 20 of the first component 14 extends into a generally ring-shaped socket 28 in the second component 16, which socket 28 is generally coaxial with the tapered pin 26. In addition, the socket 28 is provided with at least one substantially planar circumferentially and axially extending surface 30 against which a corresponding substantially planar surface 32 extending axially from the free end 34 of the first free end region 20 of the first component 14 abuts. In this manner, both rotational and bending forces can be transmitted from the second Component to the first component. It is to be understood that the expression "substantially planar" is intended to encompass any deviation from the otherwise circular circumference of the components which will permit a mechanical interlocking of the components. Thus, the substantially planar surfaces may even exhibit a degree of curvature, provided that the radius of such curvature is different to the radius of curvature of the remainder of the substantially circular region of the component. In the embodiment illustrated in Fig. 1 by way of example in which a pair of joints 12 according to the present invention are utilized, the first component 14 is, as previously mentioned, a generally omega-shaped hollow composite spring, whilst the second component 16 is a suspension arm. In addition to these components, the front suspension assembly 10 comprises a subframe 36 which may be fabricated from steel or cast in aluminium or magnesium. Alternatively, a fibre-reinforced plastic may be employed for both the subframe 36 and the spring 14. Each suspension arm 16 is attached to the subframe at a respective pivot location 38 immediately adjacent the wheels (not shown) of the vehicle. To ensure accurate and constant wheel alignment, the suspension arm 16 must of course be very stiff. On the other hand, the composite spring 14 which extends in a loop must be torsionally flexible and radially resilient, to thereby serve as the spring in the suspension assembly. The stiffness/flexibility properties of the spring 16 are attained by selecting the orientation and thickness of the layers of fibres making up the composite structure. Typically, the spring may be made from a glass fibre/epoxy composite having a diameter of 40 mm and a wall thickness of between 4 and 6 mm. In this manner, the spring can also be designed to function as an antiroll bar. Due to the inherent differences in stiffness dictated by their respective functions between the first and second components, it is advantageous if a progressive transition of rotational stiffness between the components can be attained. In this manner, a more reliable joint can be achieved. Accordingly, in accordance with a preferred embodiment of the invention, and as best illustrated in Fig. 3, the generally cylindrical first component 14 exhibits a substantially constant material wall thickness in the first end portion 18 from the mid portion 24 to the first free end region 20. Since the diameter of the first free end portion increases towards the first free end region at the same time that the material wall thickness remains constant, the quantity of material per cross sectional area increases towards the first free end region, thereby implying that the rotational stiffness increases. Advantageously, the diameter increases between 15 and 45%, preferably about 30%. In order to allow the spring 14 to act as a spring, it is resiliently supported by the subframe 36 at at least one location substantially equidistant from the two pivot locations 38. In Fig. 1, three such resilient supports are illustrated and denoted by reference numeral 40. These resilient supports are preferably in the form of rubber bushes or similar. With particular reference to Fig. 2, in a preferred embodiment of the joint according to the present invention, the socket 28 on the second member 16 and the first free end region 20 of the first component 14 each comprise a plurality of, in the shown example six, coacting planar surfaces. As is apparent from Fig. 3, the planar surfaces 32 of the first free end region 20 advantageously present a diameter which is greater than the diameter of the first end portion 18 immediately adjacent the planar surfaces 32 to thereby define a step 42 along the first end portion 18. The socket 28 on the second member 16 preferably presents a circumferential region 44 of thinner material which extends axially past the planar surfaces 23 of the first free end region 20 of the first component 14. This region of thinner material is adapted to be crimped over the step 42 on the first end portion to thereby assist in holding the joint 12 together. Advantageously, the first component 14 is a press fit on the tapered pin 26 of the second component 16 at least in the first free end region 20 of the first component. Preferably, the tapered pin 26 slightly rounded so that a gradual transition is attained between the two joined parts to thereby reduce the likelihood of stress concentration zones being formed. By coating the tapered pin with an adhesive 46 along its entire outer surface, a more even load distribution is attained over the pin. A similar effect can also be achieved by drawing a suitable plastics sleeve over the tapered pin 26. Naturally, the invention is not restricted to the embodiments described above and shown in the drawings, but may be varied within the scope of the appended claims. For example, the first and second components need not form part of a vehicle suspension system, but instead may comprise components in any system in which it is desired to achieve a torque-transmitting joint between the components. Naturally, the first component may be made of material other than a fibre/resin composite.

Claims: What is claimed is: 1. A joint (12) between an at least hollow ended, generally cylindrical first component (14) and a second component (16), said first component comprising a first end portion (18) terminating in a first free end region (20), a second end portion (22) terminating in a second free end region, and a mid portion (24) extending between said first and second end portions, said mid portion (24) presenting a first predetermined external diameter and said first end portion (18) presenting an external diameter which increases gradually from said first predetermined external diameter to a second predetermined external diameter at said first free end region (20), said first end portion being adapted to be pushed onto a tapered pin (26) extending from said second component (16) to a joined position, characterized in that in said joined position said first free end region (20) of said first component extends into a generally ring-shaped socket (28) in said second component, said socket presenting at least one substantially planar circumferentially and axially extending surface (30) against which a corresponding planar surface (32) extending axially from the free end (34) of said first free end region (20) abuts. 2. The joint as claimed in claim 1, characterized in that said generally cylindrical first component (14) exhibits a substantially constant material thickness in said first end portion (18) from said mid portion (24) to said first free end region (20). 3. The joint as claimed in claims 1 or 2, characterized in that said socket (28) and said first free end region (20) each comprise a plurality of coacting planar surfaces 30; 32). 4. The joint as claimed in claim 3, characterized in that said substantially planar surfaces (32) of said first free end region (20) occupy a diameter which is greater than the diameter of the first end portion immediately adjacent said planar surfaces to thereby define a step (42) along said first end portion. 5. The joint as claimed in claim 4, characterized in that said socket (28) presents a circumferential region (44) of thinner material which extends axially past said planar surfaces (32) of said first free end region (20), said region of thinner material being adapted to be crimped over said step (42) of said first end portion (18). 6. The joint as claimed in any of the preceding claims, characterized in that said first component (14) is a press fit on said tapered pin (26) at least in said first free end region (20) of said first component. 7. The joint as claimed in any of the preceding claims, characterized in that said tapered pin (26) is coated with an adhesive (46). 8. The joint as claimed in any of the preceding claims, characterized in that said first component (14) is made of composite fibre and said second component (16) is cast in metal. 9. The joint as claimed in claim 8, characterized in that said first component (14) is a combined spring and anti-roll bar and in that said second component (16) is a suspension arm. 10. The joint as claimed in any of the preceding claims, characterized in that the second end portion (22) of said first component is joined to a third component in the same manner as the first end portion (18) of the first component (14) is joined to said second component (16) .

Inventors: ZETTERSTROEM SIGVARD, ZETTERSTROEM, SIGVARD
Applicants: VOLVO AB, ZETTERSTROEM SIGVARD, AB VOLVO, ZETTERSTROEM, SIGVARD
Application year: 1995
Main classification: F16D1
IPC codes: B32B5, B60G7, B60G9, B60G11, B60G21, B60G25, B60N3, B60R13, B62D21, B62D25, B62D27, B62D29, F16B7, F16C1, F16D1, F16F1