GB1596837A - Motor vehicle transmission arrangements - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO MOTOR VEHICLE TRANSMISSION ARRANGEMENTS (71) We, SOCIETE AtiONYME AUTO MOBILES CITROEN, a French Body Corporate, of 17-167 Quai A. Citroen, 75747 Paris Cedex 15, France, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to motor vehicle transmission arrangements.

Protection of the joints of articulated transmission shafts of motor vehicles may be provided by flexible sleeves of the "bellows" type, particularly in the automobile industry. Play in the suspension system and angular variations in the paths taken by the wheels of an automobile in fact necessitates an arrangement which enables large dimenional variations to be taken up while at the same time protecting the joints against atmospheric corrosion and the internal wear inherent in the joints.

These sealing sleeves may be secured to, and rotatable with. the components that they protect. In this case they are subjected to stresses due in particular to the effects of centrifugal force which cause spreading of the joints, increased space-requirements in the radial direction, build-up of grease at the periphery of the assembly, and consequently inefficient lubrication of the components concerned. These sever conditions reduce their service-life.

Furthermore, protective bellows associated with oscillating components such as the driving wheels of a vehicle are required to resist the wear that is inevitably caused by the "pumping" effect resulting from the slope of the plane, along which the bellows are connected, in relation to their axis of revolution, which slope causes the folds to open and close periodically during rotation. To overcome these drawbacks, it has been proposed to block the protective sleeves against rotation.

In this case, the skirt at that end of the bellows that is nearer to the joint is secured to a fixed part of the supporting means for the joint, the other end of the sleeve surrounding the transmission shaft and being centered in relation thereto by means of a ball-bearing unit or a ring-type bearing unit which enables the shaft to rotate and seals off the joint.

This latter technique suffers from a disadvantage as regards tightness of the seal in the zone of the bearing. In fact, protection and lubrication of the joints are achieve separately, and the problem of establishing a durable seal in the zone of parts that move relatively to each other remains a delicate problem, permanent lubrication of said joints being imperative.

According to the invention, there is provided a transmission arrangement in a motor vehicle, comprising a transmission shaft, respective coupling joints connecting .he shaft with a wheel of the vehicle and with an output shaft of a drive assembly, at least one of the joints being of the ball-and-socket type, and flexible sealing means for protecting the shaft and the coupling joints, said sealing means comprising a substantially cylindrical portion surrounding the shaft and terminating at each of its ends in enlarged skirts, the skirt associated with the said one joint being of the bellows type, the cylindrical portion being integral with the skirts, the end of each skirt being secured to a non-rotating portion supporting the corresponding joint, and the substantially cylindrical portion being spaced from the shaft by means of a spacing ring freely mounted on the shaft.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawing, the sole figure of which is a crosssection of a motor vehicle transmission arrangement in accordance with the invention.

Referring to the figure, a transmission shaft 1 is adapted to be rotated by the output shaft 2 of a drive assembly part of which is shown at 3, the shafts 1 and 2 being connectd in known manner by means of a ball-and-socket joint 4. The output shaft 2 is supported by a ball-bearing unit 5.

Secured to the other end of the shaft 1 by means of a ball-and-socket joint 6 is the hub 7 of a wheel, for example, a driving wheel. This hub 7 is in turn supported by a ball-bearing unit 8 forming part of a support system 9 which can be swivelled in known manner on pivots 10.

Sealing means for protecting the ball-andsocket joints 4 and 6 is constituted by a sleeve comprising a first bellows skirt 11, which faces the ball-and-socket joint 6, a median cylindrical portion 12, which surrounds the shaft 1, and a second bellows skirt 13 which faces the ball-and-socket joint 4. The above-mentioned elements 11, 12 and 13 are connected to form a single piece. The skirt 11 is secured at its end to a cylindrical portion 14a of a flange 14 secured to the outer, i.e. fixed ring of the bearing unit 8 by means of a ferrule or clamping ring 15. Similarly, the skirt 13 is secured to a cylindrical portion 16a of a flange 16 by means of a ring 17, the flange being integral with the fixed ring of the bearing unit 5. Finally, the median portion 12 of this sleeve is spaced from the shaft 1 by a ring 18 which is freely mounted on this shaft, has antifriction properties and is lodged in a recess 19 formed in the inner wall of the portion 12. This recess constitutes a means for preventing axial movement of the ring along the shaft.

In a modified arrangement, one or other of the ball-and-socket joints can be replaced by a simpler joint, and the corresponding skirt 11 or 13 does not need to be in the form of a bellows.

The advantages of the described arrangement reside in the fact that the sleeve 11, 12, 13 encircles the entire transmision mech- anism but is of fixed location. Consequently, the problems of establishing a tight seal and preventing escape of lubricating great from the joints do not arise, the grease (or other lubricating substances) being permanently retained. Furthermore, the ring 18 does not need to be machined with any great precision since its only function is to space the sleeve from the shaft so as to prevent them from rubbing against each other and therefore becoming prematurely worn.

There is thus provided a spaced protective means, which is efficient, durable and robust, and uses a very limited number of simple strong parts which have a lengthy service-life and favourably affect the cost of producing said means.

The described sealing means can be advantageously used in the automobile industry.

WHAT WE CLAIM IS: 1. A transmission arrangement in a motor vehicle, comprising a transmission shaft, respective coupling joints connecting the shaft with a wheel of the vehicle and with an output shaft of a drive assembly, at least one of the joints being of the baland-socket type, and flexible sealing means for protecting the shaft and the coupling joints, said sealing means comprising a substantially cylindrical portion surrounding the shaft and terminating at each of its ends in enlarged skirts, the skirt associated with the said one joint being of the bellows type, the cylindrical portion being integral with the skirts, the end of each skirt being secured to a non-rotating portion supporting the corresponding joint, and the substantially cylindrical portion being spaced from the shaft by means of a spacing ring freely mounted on the shaft.

2. An arrangement according to claim 1, wherein the spacing ring is secured against axial displacement in a recess formed in the inner wall of said cylindrical portion.

3. An arrangement according to either of the preceding claims, wherein each skirt is secured by means of a ferrule to an axially-extending portion of a non-rotating flange integral with a bearing unit supporting the associated joint.

4. An arrangement according to any one of the preceding claims, wherein the second joint is a ball-and-socket joint and the second skirt is of the bellows type.

5. A transmission substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. hub 7 of a wheel, for example, a driving wheel. This hub 7 is in turn supported by a ball-bearing unit 8 forming part of a support system 9 which can be swivelled in known manner on pivots 10. Sealing means for protecting the ball-andsocket joints 4 and 6 is constituted by a sleeve comprising a first bellows skirt 11, which faces the ball-and-socket joint 6, a median cylindrical portion 12, which surrounds the shaft 1, and a second bellows skirt 13 which faces the ball-and-socket joint 4. The above-mentioned elements 11, 12 and 13 are connected to form a single piece. The skirt 11 is secured at its end to a cylindrical portion 14a of a flange 14 secured to the outer, i.e. fixed ring of the bearing unit 8 by means of a ferrule or clamping ring 15. Similarly, the skirt 13 is secured to a cylindrical portion 16a of a flange 16 by means of a ring 17, the flange being integral with the fixed ring of the bearing unit 5. Finally, the median portion 12 of this sleeve is spaced from the shaft 1 by a ring 18 which is freely mounted on this shaft, has antifriction properties and is lodged in a recess 19 formed in the inner wall of the portion 12. This recess constitutes a means for preventing axial movement of the ring along the shaft. In a modified arrangement, one or other of the ball-and-socket joints can be replaced by a simpler joint, and the corresponding skirt 11 or 13 does not need to be in the form of a bellows. The advantages of the described arrangement reside in the fact that the sleeve 11, 12, 13 encircles the entire transmision mech- anism but is of fixed location. Consequently, the problems of establishing a tight seal and preventing escape of lubricating great from the joints do not arise, the grease (or other lubricating substances) being permanently retained. Furthermore, the ring 18 does not need to be machined with any great precision since its only function is to space the sleeve from the shaft so as to prevent them from rubbing against each other and therefore becoming prematurely worn. There is thus provided a spaced protective means, which is efficient, durable and robust, and uses a very limited number of simple strong parts which have a lengthy service-life and favourably affect the cost of producing said means. The described sealing means can be advantageously used in the automobile industry. WHAT WE CLAIM IS:

1. A transmission arrangement in a motor vehicle, comprising a transmission shaft, respective coupling joints connecting the shaft with a wheel of the vehicle and with an output shaft of a drive assembly, at least one of the joints being of the baland-socket type, and flexible sealing means for protecting the shaft and the coupling joints, said sealing means comprising a substantially cylindrical portion surrounding the shaft and terminating at each of its ends in enlarged skirts, the skirt associated with the said one joint being of the bellows type, the cylindrical portion being integral with the skirts, the end of each skirt being secured to a non-rotating portion supporting the corresponding joint, and the substantially cylindrical portion being spaced from the shaft by means of a spacing ring freely mounted on the shaft.

2. An arrangement according to claim 1, wherein the spacing ring is secured against axial displacement in a recess formed in the inner wall of said cylindrical portion.

3. An arrangement according to either of the preceding claims, wherein each skirt is secured by means of a ferrule to an axially-extending portion of a non-rotating flange integral with a bearing unit supporting the associated joint.

4. An arrangement according to any one of the preceding claims, wherein the second joint is a ball-and-socket joint and the second skirt is of the bellows type.

5. A transmission substantially as hereinbefore described with reference to the accompanying drawings.