FORM 2
THE PATENT ACT 1970 (39 of 1970)
The Patents Rules, 2003 COMPLETE SPECIFICATION 'See Section 10, and rule 13
1. TITLE OF INVENTION
ARTICULATION UNIT, PREFERABLY FOR SUPPORTING THE DRIVE MECHANISM CONNECTION ROD OF A MOTOR VEHICLE


2.

APPLICANT(S)

a) Name
b) Nationality
c) Address

ZF FRIEDRICHSHAFEN AG GERMAN Company 88038 FRIEDRICHSHAFEN GERMANY

3.

PREAMBLE TO THE DESCRIPTION

The following specification particularly describes the invention and the manner in which it is to be performed : -


The invention relates to an articulation unit, preferably for supporting the drive mechanism connection rod of a motor vehicle, having a connecting-rod-side housing in which a pivot pin is pivotably received by means of a spherical bearing face, the articulation unit having a safety unit to prevent the housing and the pivot pin from becoming separated.
Wheel suspensions in motor vehicles have bearings and articulations which have different functions depending on requirements. For example, the articulations serve to allow a relative movement of two components with several degrees of freedom. Furthermore, there are also known articulation units which have specific damping properties for oscillations which are.produced via the wheels of the motor vehicle.
The vast majority of articulation units which are used in drive mechanism components are safety components on which a high load is placed and which are generally constructed to provide operational safety for the entire service-life of a motor vehicle in accordance with the Safe Live principle, that is to say, with multiple safety features. However, events or very unfavourable coincidences are conceivable and may lead to the complete failure of the articulation units which are generally used.
For example, particular wear of the bearing shell or the pivot pin is conceivable and may occur owing to failure of the sealing systems used in such articulation units as a result of impurities or water entering the interior of the articulation. The most serious consequence of such a failure of the articulation units would be that the connection between the housing and pivot pin of the damaged articulation unit would become completely disengaged. Such a separation of the significant articulation components must be prevented completely for safety reasons.
In order to prevent such occurrences, there are known from the prior art safety units which prevent complete separation of the housing and the pivot pin so that an articulation which is damaged in this manner is at least still provided with an
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emergency operation function which allows the relevant vehicle to be driven to the nearest garage.
For example, DE 10 2004 055 961 Al discloses an articulation unit which has the generic features and which is provided with a safety unit which is referred to in this instance as a catch device in which at least one flexible catch strip or at least one curved safety member is provided with a recess into which a catch pin of the housing protrudes in a contact-free manner during normal operation. Although such a catch device can clearly prevent the housing and pivot pin from becoming separated, it is always necessarily arranged in the outer region of the relevant articulation unit owing to the construction-related structural size thereof. However, the visual presence of the objectively desirable and necessary safety system consequently provides subjectively for the user an articulation unit which, owing to its specific configuration, might not give the impression of safety of an articulation unit which was provided with a redundant safety unit which cannot be seen from the outer side.
The object of the present invention is therefore to develop an articulation unit of the generic type in such a manner that, on the one hand, even in the event of an occurrence of complete separation of the housing and pivot pin, an emergency operation function of the articulation unit continues to be ensured and, on the other hand, the safety unit which is accordingly used for this purpose does not involve any obtrusive configuration of the articulation unit with regard to its structural size.
The object addressed is achieved, when considered together with the generic features of claim 1, by the technical teaching disclosed in the characterising portion.
It is inventively significant that the safety .unit for preventing separation of the housing and pivot pin of the articulation unit has a securing pin, which is arranged inside the pivot pin substantially parallel with the longitudinal centre axis thereof and which is provided at one of the free ends thereof with a locking element, and a
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securing recess which is located inside the housing or the pivot pin and in which the locking element is received in a contact-free manner when the articulation unit is in the mounted state, the securing pin being fixed to the component of the articulation unit (housing or pivot pin) which is not provided with the securing recess.
In contrast to all solutions for a safety unit known from the prior art, the inventively significant teaching provides a constructive solution which can be accommodated completely within the conventional structural dimensions of an articulation unit. In this manner, the specific provision of the additional safety unit in such an articulation unit is no longer visible from the outer side, with the result that users and vehicle owners no longer have the feared reservations.
Specific configurations of the subject-matter of the invention will further be appreciated from the features of the subsidiary claims.
For example, a developed configuration of the locking element makes provision for the locking element to have at least two projections which protrude symmetrically over the cross-section of the securing pin. Projections may be constructed in the form of an end web at the free end of the securing pin. The securing pin is as a whole secured to the associated housing or pivot pin by means of a screw connection. In addition, other fixing possibilities are naturally also conceivable. The construction of the locking element together with the elongate construction of the securing pin affords a simple possibility for providing, at a free end of the securing pin, an end component which co-operates with the securing recess and which is constructed in a simple manner and is simple to produce.
The securing recess has, together with the specific configuration of the securing pin, delimiting faces which are directed towards the inner side of the articulation unit and which engage behind the locking element described above. The securing recess may in addition have an insertion opening for a securing pin directed towards the inner side of the articulation unit; the cross-section of the insertion opening is
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constructed in a substantially rectangular manner, the longer side dimension of the rectangular cross-section allowing the locking element of the securing pin to be inserted through the insertion opening and the other side dimension of the rectangular cross-section being smaller than the width dimension of the projections of the locking element. This structural configuration produces a so-called bayonet connection in which, after being inserted through the insertion opening of the securing recess, the securing pin is rotated, for example, through 90 degrees, an axial movement of the pin then being prevented by the delimiting faces which are provided within the securing recess, so that the housing and the securing pin which is fixed to the pivot pin are then also prevented from becoming separated.
Another advantageous configuration of the articulation unit according to the invention involves the housing being constructed as a cast component in which the securing recess is completely formed as a recess. Since, during normal operation, the locking element of the securing pin generally provides a contact-free or almost contact-free positioning in the securing recess of the housing, a recess which is produced in the housing during the casting operation advantageously does not need to be processed further as long as the appropriate casting tolerances are complied with.
Furthermore, for specific applications, an advantageous development of the subject-matter of the invention involves the housing being constructed as a cast component, the securing recess being formed as a recess and the delimiting faces, in terms of their co-operative function with the locking element of the securing pin, being inserted into the recess of the housing as separate sheet metal elements. Such a configuration may, under some circumstances, lead to a more cost-effective production of the articulation unit.
Since the articulation units used are often used in regions of the motor vehicle drive mechanism or steering mechanism, which are not accessible for regular visual inspection, it may further be advantageous to arrange, between the housing and
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pivot pin, an electronic sensor element which monitors and indicates a separation of the housing and pivot pin.
Although the configuration according to the invention prevents a separation of the articulation unit, such an articulation unit is in any case damaged in such a manner that it must be replaced as quickly as possible. In accordance with the configuration of the articulation unit with a sensor unit, this can be achieved as quickly as possible after the damage has occurred by the vehicle user, within the context of the generally provided computer diagnostics of the vehicle monitoring system, being instructed to seek a garage as quickly as possible in order to rectify the problem.
For the configuration of the electronic sensor element, different construction variants may be used.
An embodiment of the subject-matter of the invention will be explained below in greater detail with reference to the appended drawings, in which;
Figure 1 is a sectioned illustration of a first embodiment of the articulation unit according to the invention,
Figure 2 is a plan view of the articulation unit of Figure 1 in accordance with the view BB, and
Figure 3 is a sectioned illustration of another construction variant of the articulation unit according to the invention.
In the embodiment illustrated in Figure 1 of a construction variant of the articulation unit according to the invention, the significant features according to the invention can be explained, but this variant or the other construction variant of Figure 3 do not indicate a limitation to the subject-matter specifically illustrated. In the individual
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Figures, consistent reference numerals are used below in so far as they are used for components or component groups which are the same.
The articulation unit in Figure 1 has a housing 1 on which the connection region of a connection rod pair 7, 8 of a triangular connection rod for a motor vehicle is formed.
In the structure illustrated as a configuration which is open at one side, the housing 1 has an inner hollow space in which a bearing shell 6 is inserted. The bearing shell allows within the articulation unit a supporting function which damps vibrations and which at the same time has sliding properties. The bearing shell 6 receives, when viewed inwards in the direction towards the articulation, the spherical bearing face 3 of an articulation ball 3.1. The articulation ball 3.1 is secured to a pivot pin 2. A securing ring 11 is used to secure the bearing shell 6 against axial movement out of the opening of the housing 1.
The pivot pin 2 is an integral component of a recess 4, the integral component of which is a connection flange 5 by means of which the articulation unit is generally screwed to a retaining member at the shaft side.
According to the invention, inside the articulation unit illustrated is a safety unit which substantially comprises a securing pin 9 which is received in a hole 10 of the pivot pin 2 and a securing recess 13. The securing pin 9 extends through the entire pivot pin 2 including the shaft-side recess 4 and has, at the upper free end thereof facing the housing 1, a locking element 12. The locking element engages in the securing recess 13 which is located inside the housing 1. The securing recess 13 is an integral component of the upper portion of the housing 1 and has, at the lower side thereof facing the pivot pin 2, in the embodiment illustrated, two delimiting faces 14a and 14b which are constructed as projections which protrude into the securing recess. Consequently, the delimiting elements 14a and 14b and the upper side of the securing recess 13 which is constructed in the form of a chamber form a gap in which the locking element 12 engages in such a manner that both upward and downward
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movement of the securing pin 9 is prevented. To this end, according to an advantageous configuration, the locking element 12 is provided with at least two projections 15a and 15b which protrude symmetrically over the cross-section of the securing pin 9. The two projections 15a and 15b form the shape of an end web 16 as is clear in particular from the plan view of Figure 2.
The securing pin which is provided at one end with the end web 16 is in principle constructed from a hexagonal screw 17, on the upper end of which facing away from the screw head, an attachment with the locking element 12 is screwed onto the thread of the hexagonal screw. Consequently, the securing pin 9 is secured inside the pivot pin 2.
As can be seen from Figures 1 and 3, the specific structural configuration of the securing pin 11 with the locking element 12 thereof and the securing recess 13 which co-operates with the locking element 12 ensures that the housing 1 is prevented from becoming separated from the pivot pin 2, for example, as a result of increased wear of the articulation ball 3.1 or the bearing shell 6, with the housing 1 being prevented from being lifted from the pivot pin 2. In the normal operating state of the articulation unit, the dimensions of the locking element 12 which is received in the securing recess 13 are of such a size that the mutually adjacent components do not touch and all movement directions which the articulation unit allows between the pivot pin and housing are provided via the spherical bearing face 3 together with the bearing shell 6.
From Figure 2, it can additionally be seen that the securing recess 13 has, at the side thereof directed towards the inner side of the articulation unit, in the region of the delimiting elements 14a and 14b, an insertion opening 18 for the securing pin 9. The insertion opening 18 is constructed substantially with a rectangular cross-section, the longer side dimension of the cross-section being selected in such a manner that the locking element 12 with respect to the end web 16 which forms this locking element can be inserted through the insertion opening when rotated correctly into position. If
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the end web 16 is inserted through the insertion opening 18, the securing pin 9 is rotated through 90 degrees so that the lower sides of the projections 15a and 15b are located above the delimiting elements 14a and 14b. In this position of the locking element 12, an axial movement of the pivot pin 2 is prevented or is possible only to the extent oi the spacing of the projections 15a and 15b with respect to the upper side of the delimiting faces 14a and 14b. The construction variant illustrated allows a closed shape of the housing 1 at the upper side thereof and at the same time facilitates the corresponding assembly of the securing pin 9.
The additionally illustrated construction variant of Figure 3 of the articulation unit according to the invention differs from the illustration of Figure 1 with respect to the configuration of the delimiting elements 14a and 14b. In Figure 1, the housing 1 is constructed as a cast component, the delimiting elements 14a and 14b which belong to the securing recess 13 being constructed integrally with the housing 1, so that the securing recess 13 is completely formed as a recess in the housing.
In the configuration of Figure 3, the housing 1 is also constructed as a cast component, the securing recess 13 also being formed as a recess in the housing 1. However, in this configuration, the delimiting elements 14a and 14b are an integral component of a separate sheet metal element which is clamped within the housing between a projection and a securing ring 19.
In order to allow the vehicle user to identify a bearing unit which is protected against separation of the housing 1 and pivot pin 2 by the safety unit as nonetheless being defective, it is schematically illustrated in Figure 1 that, between the housing 1 and pivot pin 2, an electronic sensor element 20 can be arranged. The sensor element 20 is referred to as a so-called "black box" in the illustration of Figure 1, it being possible for it to be constructed, on the one hand, as a receiving member for the possible, if only slight, axial movement between the housing 1 and pivot pin 2, it being possible at the same time for a corresponding electronic evaluation system to be associated with the entire on-board electronic system of modern motor vehicles.
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In any case, owing to this additional equipment, it is possible for the vehicle user to determine a failure of the articulation unit and consequently to carry out the replacement of the corresponding defective component as quickly as possible.
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List of reference numerals
1 Housing
2 Pivot pin
3 Spherical bearing face
3.1 Articulation ball
4 Recess
5 Connection flange
6 Bearing shell
7 Connection rod arm
8 Connection rod arm
9 Securing pin
10 Hole
11 Securing ring
12 Locking element
13 Securing recess
14a Delimiting element
14b Delimiting element
15a Projection
15b Projection
16 End web
17 Hexagonal screw
18 Insertion opening
19 Securing ring
20 Sensor element

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CLAIM:
1. Articulation unit, preferably for supporting the drive mechanism connection
rod of a motor vehicle, having a connection-rod-side housing (1) in which a
pivot pin (2) is pivotably received by means of a spherical bearing face (3), the
articulation unit having a safety unit to prevent the housing (1) and the pivot
pin (2) from becoming separated,
characterised in that
the safety unit has a securing pin (9) which is arranged inside the pivot pin (2) substantially parallel with the longitudinal centre axis of the pivot pin (2) and which is provided at one of the free ends thereof with a locking element (12) and a securing recess (13) which is located inside the housing (1) or the pivot pin (2) and in which the locking element (12) is received in a contact-free manner when the articulation unit is in the mounted state, the securing pin (9) being fixed to the component of the articulation unit (housing (1) or pivot pin (2)) which is not provided with the securing recess (13).
2. Articulation unit according to claim 1,
characterised in that
the locking element (12) has at least two projections (15a, 15b) which protrude symmetrically over the cross-section of the securing pin (9).
3. Articulation unit according to claim 2,
characterised in that
the projections (15a, 15b) are constructed in the form of an end web (16) at the free end of the securing pin (9).
4. Articulation unit according to either claim 1 or 2,
characterised in that
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the securing pin (9) is constructed in the form of a hexagonal screw (17), on the free end of which facing away from the screw head, an attachment which is provided with the locking element (12) is secured.
5. Articulation unit according to any one of claims 1 to 4,
characterised in that
the securing recess (13) has delimiting elements (14a, 14b) which are directed towards the inner side of the articulation unit and which engage below the locking element (12).
6. Articulation unit according to any one of claims 2 to 5,
characterised in that
the securing recess (13) has for the securing pin (9) an insertion opening (18) which is directed towards the inner side of the articulation unit and whose cross-section is constructed in a substantially rectangular manner, the longer side dimension of the insertion opening (18) allowing the locking element (12) of the securing pin (9) to be inserted through and the other side dimension of the cross-section being smaller than the width dimension of the projections (15a, 15b) of the locking element (12).
7. Articulation unit according to any one of claims 1 to 6,
characterised in that
the housing (1) is constructed as a cast component wherein the securing recess (13) is completely formed as a recess.
8. Articulation unit according to either claim 5 or claim 6,
characterised in that
the housing is constructed as a cast component, the securing recess (13) being formed as a recess and the delimiting faces (14a, 14b) being an integral component of a separate sheet metal element which is inserted into the recess of the housing (1).
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9. Articulation unit according to any one of claims 1 to 8, characterised in that,
between the housing (1) and pivot pin (2), there is arranged an electronic sensor element (20) which monitors and transmits a separation of the housing (1) and pivot pin (2).
Dated this .1?* day of February, 2009
HIRAL CHANDRAKANT JOSHI AGENT FOR ZF FR1EDRICHSHAFEN AG