Sleeve joint, in particular for a vehicle

A sleeve joint (1), in particular for a vehicle, having an outer sleeve (3) which receives and secures a ball socket (9), in an axial direction. The ball socket (9) is composed of a plastics material for engagement with an inner ball joint body (5). The ball socket (9) extends radially as far as an inner wall (11) of the outer sleeve, such that the ball socket (9) is supported directly on the outer sleeve (3).

This application is a National Stage completion of PCT/EP2017/073560 filed Sep. 19, 2017, which claims priority from German patent application serial no. 10 2016 220 438.6 filed Oct. 19, 2016.

FIELD OF THE INVENTION

The invention relates to a sleeve joint.

BACKGROUND OF THE INVENTION

From DE 10 2012 207 527 A1 a sleeve joint is known, which comprises an inner ball sleeve and an outer sleeve. Between the two sleeve elements is arranged a ball socket for the ball sleeve. An inner sleeve supports the ball socket on the outer sleeve. The components present in the outer sleeve are secured axially by locking rings at the ends, which are in each case braced against the inner sleeve by rolling over the outer sleeve at the ends.

All the components are brought into the production process as individual parts, which are closed in by the rolling-over process. The friction torque between the ball sleeve and the ball socket can be adjusted by the axial prestressing of the locking rings.

The advantage of such a sleeve joint is that components that are in some way defective, for example having incorrect friction, can be dismantled again by puncturing the outer sleeve. Their disadvantage, however, is the number of components involved and the consequent cost and complexity of assembly.

SUMMARY OF THE INVENTION

The purpose of the present invention is develop further a sleeve joint with a view to optimizing its production process.

This objective is achieved if the ball socket extends radially as far as an inside wall of the outer sleeve, so that the ball socket is supported directly on the outer sleeve.

The great advantage of the invention is that compared with the prior art mentioned, the number of components needed is drastically reduced.

According to a further advantageous feature, the outer sleeve has a rim facing radially inward which, with the ball socket, forms an interlocking connection. This interlocking connection prevents any lateral drifting of the ball socket out of the outer sleeve.

According to the claims, it is provided that the ball socket extends over the outer sleeve and has a holding groove for a sealing bellows. This saves an additional component previously required for attaching the sealing bellows.

With a view to comprehensive corrosion protection, at least an inner shell surface of the bent-over rim is covered by the ball socket. Particularly at end faces, defects are formed during surface coating with paint or, for example, by galvanizing, which surfaces are now in fact no longer exposed to environmental influences.

To increase the axial load-bearing ability of the sleeve joint, an angle enclosed by the inside wall of the outer sleeve and the bent-over rim is smaller than or equal to 90°. By choosing an angle of that size, under radial loading the bent-over rim would first have to be pushed up by more than 90° before the ball socket can move out of the predetermined fitting position within the outer sleeve.

Having regard to a simple design of a production device, the inner ball joint body has a holding groove for the sealing bellows, such that the maximum diameter of the groove profile is smaller than the smallest diameter of the ball socket. In that way a device slider can move past onto the fixing groove in the direction of the ball socket.

Optionally, the outer sleeve can have an interlocking profile in the direction of the ball socket, in order to prevent any relative rotational movement between the ball socket and the outer sleeve.

Preferably, the interlocking profile is formed by at least one, at least segment-like flange. Of course the flange can be circular and extend over the entire circumference of the outer sleeve.

With a view to the most flexible possible production the inside diameter of the outer sleeve in the area of the bent-over rim is at least as large as the maximum diameter of the ball joint body. Thus, the ball joint body can be pushed into a finish-machined outer sleeve in order to continue the subsequent assembly.

The ball socket is preferably made of a fiber-reinforced plastic. The fiber content increases the strength of the ball socket. Preliminary tests have shown that with a fiber content of around 30% a good compromise between strength and sliding properties can be achieved. Alternatively, the ball socket can be made of glass-bead-reinforced plastic.

Basically, it would be possible for the fibers to be made of a glass-like material. For optimum friction properties, however, fibers of a carbon material have given better results.

Optionally, the outer sleeve has a connection opening for the introduction of liquid plastic. The connection opening produces no visual blemish since in most application cases the outer sleeve is press-fitted into a supporting component, so that the connection opening is covered.

A further measure for simplifying the production of the ball joint consists in inserting the ball joint body into the outer sleeve and holding it in a definite position in an injection die, so that the ball socket is produced by injecting an injectable plastic composition which fills a free space between the ball joint body and the outer sleeve.

Thus, the ball socket is not produced as a solid component, but only produced by injection-molding in a device in which the outer sleeve and the ball joint body are already fixed.

In a first embodiment of the method the plastic composition is injected through the connection opening into the free space. This variant makes little demands on the injection device.

Alternatively, the possibility exists of injecting the plastic composition via an annular gap between the outer sleeve and the ball joint body. This simplifies the outer sleeve. In addition, theoretically the entire end face of the ball socket can serve as an injection-molding cross-section so that the plastic volume can be introduced into the device in a very short cycle time.

With regards to reducing the friction torque inside the ball joint it has been found to be very effective for the ball joint to undergo a post-heating operation following the injection-molding process.

Preferably, the bent-over rim of the outer sleeve is given its shape before the injection-molding process of the plastic composition. In that way the outer sleeve can be fully finish-machined and then moved on to the rest of the production process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a sleeve joint1with a metallic outer sleeve3and an inner ball joint body5. The ball joint body5extends through the outer sleeve3on both sides, so that the ball profile, in cross-section, is only limited to a ball section7. In this example the ball joint body5is in the form of a sleeve, but a solid component can be used just as well. Between the ball joint body5and the outer sleeve3is arranged a ball socket made of a plastic material. The ball socket9is supported on one hand directly on the ball joint body5and on the other hand directly on an inside wall11of the outer sleeve3, so that the ball socket9is also supported directly on the outer sleeve3.

The plastic material is fiber-reinforced, preferably with glass fibers or carbon fibers. Alternatively, the plastic material can be reinforced with glass beads.

InFIGS. 2 and 3the outer sleeve3is shown as an individual component having a rim13;15at each end bent over radially inward. An angle α enclosed between the inside wall11of the outer sleeve3and the bent-in rim13;15should preferably be smaller than or equal to 90° (seeFIG. 2). Furthermore, particularly inFIG. 3in the area of a shell surface17a connection opening19for the injection of liquid plastic can be seen. The outer sleeve is prefabricated as a separate component and passed on to the remainder of the production process.

As shown by an overall view ofFIGS. 1 and 4, the inside diameter of the outer sleeve3in the area of the bent-over rim13;15is at least as large as the maximum diameter of the ball joint body5, in particular that of the ball section7. This makes it possible to insert the ball joint body5into the outer sleeve3even when the rim13;15on the outer sleeve3is already fully formed.FIG. 4shows an intermediate assembly condition in which the ball joint body5has been pushed into the outer sleeve3but the ball socket9has not yet been produced.

In the intermediate assembly condition according toFIG. 4, the still unfinished assembly is placed in a defined position in an injection-molding die21. In this, there is a free space23for the ball socket9to be produced by an injection-molding process, in which an injection-moldable plastic composition fills the free space23in accordance with the shape produced by the injection-molding die21. The plastic composition can be injected by way of the connection opening19in the outer sleeve3or even by way of an annular gap25between the outer sleeve3and the ball joint body5. The inherent elasticity of the ball socket9can be determined by virtue of various process parameters such as holding pressure and/or injection pressure of the plastic composition.

In the finished condition shown inFIGS. 1 and 5, the rim13;15facing inward forms in each case an interlock connection27;29with the ball socket9. Here, an inside shell surface and even a cover surface31of the bent-over rim13;15can be covered by the plastic composition of the ball socket and in that way can protect a particularly corrosion-critical area (seeFIGS. 2 and 3).

FIG. 5in particular shows a holding groove33in the ball joint body5for a sealing bellows (not shown) designed to cover the free area of the ball joint body5so that no dirt can make its way into the contact area between the ball socket9and the ball joint body5. By showing a slider (seeFIG. 1) inside the injection-molding die21it can be seen that the ball socket9extends axially over the outer sleeve3and has a holding groove37for the sealing bellows. A maximum diameter of the holding groove33is made smaller than the smallest diameter of the ball socket9outside the contact surface. Consequently, a comparatively simple die configuration can be provided in order to produce even more extensive geometries.

After the end of the injection-molding process of the plastic composition, a post-heating operation can also be carried out. Depending on the component configuration, the sleeve joint1is tempered for a few minutes or even for a longer time at between 40° C. and 80° C. In this way the component as a whole can set, which substantially improves the friction behavior of the sleeve joint1.

FIGS. 6, 6A, 7 and 7Apresent a further development of the outer sleeve3, in which an interlocking profile39is formed in the design of at least one, at least segment-like flange. The basic shape of the outer sleeve3is identical to the design according toFIGS. 1 to 5. The flanges39are intended to ensure that no relative rotational movement can ever take place between the outer sleeve3and the ball socket9. Furthermore, thereby higher axial forces can also be withstood by the sleeve joint1. Circular flanges, but also curved flanges can be provided. The representation is to be understood as showing only an example.

After the ball joint1has been removed from the injection-molding die21, as already described a post-heating operation can be carried out. However, the sleeve joint can already fulfill its basic function and for that does not require any finish-machining. Finally, the sealing bellows is fixed into the holding grooves33;37of the ball socket9and the ball joint body5.

FIGS. 8, 8A, 9 and 9Ashow further possible variants of the outer sleeve3, each represented in section (FIGS. 8A, 9A) and viewed laterally from above (FIGS. 8, 9). In the variant shown inFIGS. 8 and 8Athe outer sleeve3is provided with an all-round groove41in the central area (“equator area”). The all-round groove41separates the outer sleeve3into two areas of equal size.

In the variant shown inFIGS. 9 and 9A, the outer sleeve3is provided with two all-round grooves43,45. The all-round grooves43,45are a distance apart from one another and are respectively separated uniformly by a central area47(“equator area”) of the outer sleeve3(symmetrically relative to the equator area). As indicated by the dimensions shown in the lateral view from above, the equator area between the grooves43,45had an outer diameter D2which is smaller than the respective outer diameters D1of the edge areas of the outer sleeve3located outside the equator area.

Both of the variants shown inFIGS. 8, 8A and 9, 9Ahave the advantage that owing to the design of the central area, the outer sleeve3contributes toward reducing the torques of the sleeve joint, particularly in the condition after fitting. The reduction results from the fact that in the press-fitted condition of the joint, the central area is less severely deformed.

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