WO2002075170A1

WO2002075170A1 - A screw joint

Info

Publication number: WO2002075170A1
Application number: PCT/SE2002/000456
Authority: WO
Inventors: Henrik Ask
Original assignee: Volvo Lastvagnar Ab
Priority date: 2001-03-21
Filing date: 2002-03-12
Publication date: 2002-09-26
Also published as: SE0100980D0; SE521090C2; SE0100980L

Abstract

The invention relates to a screw joint arrangement for interconnecting a first component (11) and a second component (12). The arrangement comprises a screw (20) which extends through a screw hole (23) in the first component into a screw hole (21) in the second component and in this connection interacts with an expansion locking means. This comprises an inner sleeve part (17) and an outer sleeve part (13), which sleeve parts are provided with interacting spherical surfaces (15, 19) which make it possible to angle the inner sleeve part (17) in relation to the outer (13).

Description

TITLE

A screw joint

TECHNICAL FIELD

The present invention relates to a screw joint arrangement for interconnecting a first component and a second component, comprising a screw which extends through a screw hole in the first component into a screw hole in the second component and in this connection interacts with an expansion locking means comprising an inner sleeve part and an outer sleeve part.

BACKGROUND

When two components, which are individually rigidly mounted (that is to say have a fixed position) , have to be interconnected by means of a screw joint, there are often problems of mutual positional deviation between the objects at the connection location. The positional deviations vary between individual items and are unavoidable unless tolerance requirements in manufacture and assembly are unreasonably stringent.

Problems caused by the positional deviations can be divided into three main types:

1. Positional deviation between the center lines of the screw holes. This is nevertheless generally solved in a simple manner by having clearance holes for the screw.

2. Axial play between interacting support surfaces. Results in stresses being built in when the joint is assembled. 3. Inclination between interacting support surfaces. This results in there being on the one hand only linear contact between joined-together surfaces, which produces large indentations, and on the other hand undesirable flexural stresses in the screw when the joint is assembled.

EP0633404 describes an expansion locking means with conical sleeve parts, an outer one of which is slotted, which makes it possible to compensate for axial tolerance errors according to point 2 above. However, this known arrangement does not compensate for inclination according to point 3 above.

DISCLOSURE OF THE INVENTION

One object of the invention is therefore to. bring about a screw joint arrangement which makes possible stress- free interconnection of a first component and a second component.

To this end, the invention relates to a screw joint arrangement for interconnecting a first component and a second component, comprising a screw which extends through a screw hole in the first component into a screw hole in the second component and in this connection interacts with an expansion locking means comprising an inner sleeve part and an outer sleeve part, characterized in that the sleeve parts are provided with interacting spherical surfaces which make it possible to angle the inner sleeve part in relation to the outer. By virtue of this design of the invention, an opportunity is obtained in a simple manner for compensating for on the one hand axial errors and on the other hand inclinations. This compensation can take place automatically on assembly of the screw joint.

The inner sleeve part is suitably provided with an external spherical surface, and the outer sleeve part is suitably provided with an internal spherical surface . Further advantageous variants of the invention are indicated in the subsequent subclaims .

BRIEF DESCRIPTION OF FIGURES The invention will be described in greater detail below with reference to illustrative embodiments shown in the accompanying drawings, in which

FIG 1 is a longitudinal section through a screw joint according to a first illustrative embodiment of the invention, and

FIG 2 shows in a corresponding manner a second illustrative embodiment of the invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS The screw joint 10 shown in Figs 1 and 2 is used in order to interconnect a first component 11 and a second component 12.

Mounting an auxiliary unit in an internal combustion engine may be mentioned as an example of an area of application of the invention. The screw joint can therefore be used in an angle bracket between a turbo- compound unit and an engine block. By virtue of the fact that a turbo-compound unit normally constitutes a relatively heavy unit, which is at one of its ends connected via a transmission case to the crankshaft of the engine, and is subjected to the vibrations of the engine, an angle bracket is required for connection to the engine block. As the turbo-compound unit forms a tolerance chain, a possibility of adjustment is required in order that harmful forces do not arise at the connection to the engine block attachment. Even if an adjustment possibility is available, there is a risk of incorrect mounting.

The screw joint comprises an outer sleeve 13 with a cylindrical outer side 14, a spherical concave surface 15 on the inner side and a spherical convex surface 16 on one short side. The screw joint moreover comprises an inner sleeve 17 which has a cylindrical inner side 18 and a spherical convex outer side 19, with the same spherical surface radius as on the outer sleeve 13.

A screw 20 extends through both sleeves 13, 17, and also through a hole 21 in the second component 12, and interacts with a nut 22. The outer sleeve 13 is received in a hole 23 in the first component 11. The center of the radii of the spherical surfaces coincides with the center line of the sleeves.

When the screw joint is assembled, the outer sleeve 13 is positioned with a loose fit in the hole 23 in the first component 11, after which the inner sleeve 17, the screw 20 and the nut 22 are assembled. When the screw 20 is tightened, the outer sleeve will first slide axially in the hole 23 until the spherical surface on the short side of the outer sleeve comes up against a likewise spherical, concave surface 24 on the opposite component 12. The spherical surfaces provide a perfectly satisfactory contact surface even if there is inclination between the objects.

The inner sleeve 17 can rotate freely inside the outer sleeve 13, and the screw head will therefore straighten up the inner sleeve as the screw is tightened, so that on the one hand a full contact surface is obtained between the screw head 20a and the sleeve 17, and on the other hand the bending moment is eliminated and the load on the screw thus becomes purely axial. When the screw is tightened further, the inner sleeve 17 will press the outer sleeve 13 apart, and, by virtue of the fact that the latter is relatively weak (thin-walled) , it will expand radially and be fixed axially in its position in the hole 23.

The screw holes 13a, 18 through the sleeves 13, 17 are clearance holes so as to be capable of taking up radial positional errors, and the hole 13a through the outer sleeve 13 has been made slightly larger than the hole 18 through the inner sleeve 17 as it also has to be capable of compensating for inclination.

The adaptation in the axial direction and in angle described above takes place automatically and results in a stress-free interconnection between the two components .

An alternative embodiment is shown in Fig. 2, where a thread 25 in the material is used instead of a nut.

The invention is not to be regarded as being limited to the illustrative embodiments described above, but a number of further variants and modifications are conceivable within the scope of the patent claims below. For example, it is possible to provide the outer sleeve 13 with a slot which influences the deformation in the radial direction.

Claims

PATENT CLAIMS

1. A screw joint arrangement for interconnecting a first component (11) and a second component (12), comprising a screw (20) which extends through a screw hole (23) in the first component into a screw hole (21) in the second component and in this connection interacts with an expansion locking means comprising an inner sleeve part (17) and an outer sleeve part (13), characterized in that the sleeve parts (13, 17) are provided with interacting spherical surfaces (15, 19) which make it possible to angle the inner sleeve part

(17) in relation to the outer (13) .

2. The arrangement as claimed in claim 1, characterized in that the inner sleeve part being provided with an external spherical surface (19) and the outer sleeve part being provided with an internal spherical surface (15) .

3. The arrangement as claimed in claim 2, characterized in that the outer sleeve part (13) is moreover provided with an external spherical surface (16) for interaction with a support surface (24) on one of the components (12) .

4. The arrangement as claimed in claim 3, characterized in that the support surface (24) is concave.

5. The arrangement as claimed in any one of claims 1 to 4, characterized in that the spherical surface (19) of the inner sleeve part (17) has a smaller radius of curvature than the external spherical surface (16) of the outer sleeve part (13) .

6. The arrangement as claimed in claim 5, characterized in that the center for the radii of the external spherical surfaces (16, 19) of the two sleeve parts (13, 17) coincides with the center line of the sleeves .