ZWARTS, Jacobus (Carmenlaan 5, VA Niuwegein, NL-3438, NL)
VISSER, Carl Petrus Antonius (Litserstraat 67, 5275 BT Den Dungen, NL)
KAPAAN, Hendrikus, Jan (Waterhoen 5, DM Nieuwegein, NL-3435, NL)
ZWARTS, Jacobus (Carmenlaan 5, VA Niuwegein, NL-3438, NL)
VISSER, Carl Petrus Antonius (Litserstraat 67, 5275 BT Den Dungen, NL)
CLAIMS
1. A connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) for transmitting, in a motor vehicle, the driving torque between a first member (110, 510, 710, 910) and a second member (120, 520, 620, 720, 820, 920, 1020), with both members and the connector being rotatable around a same axis (X), characterized in that the connector comprises :
- a first part (131 , 531 , 731 , 931 ) with a first connector surface (131 a, 331 a, 531a, 631 a, 731 a, 931a) for mating with said first member (1 10, 510, 710, 910),
- a second part (132, 532, 732, 932) with a second connector surface on a radially inner circumferential end (132a, 332a,
532a, 732a, 932a) for mating with said second member (120,
520, 620, 720, 820, 920, 1020), said first part (131 , 531 , 731 , 931) and second part (132, 532, 732, 932) extending substantially axially along the axis (X) so that the radial distance from said first part (131 , 531 , 731 , 931 ) to the axis (X) is greater than the radial distance from said second part (132, 532, 732, 932) to the axis (X).
2. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to claim 1 , characterized in that it further comprises a third part (133,
533, 733, 933) for interconnecting said first part (131 , 531 , 731 , 931 ) and said second part (132, 532, 732, 932).
3. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to claim 2, characterized in that the third part (133, 533, 733, 933) is substantially perpendicular to the axis (X).
4. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to claim 1 , characterized in that the first connector surface (131a, 331 a, 531a, 631 a, 731a, 931a) is a radially outer circumferential surface of the first part (131 , 531 , 731 , 931 ).
5. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to claim 1 , characterized in that the first connector surface (131a, 331 a, 531a, 631a, 731a, 931a) is a radially inner circumferential surface of the first part (131 , 531 , 731 , 931 ).
6. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to claim 2, characterized in that the third part (133, 533, 733, 933) abuts against a shoulder of one or both the first member (110, 510, 710, 910) and second member (120, 520, 620, 720, 820, 920, 1020) so as to define an axial stop means for the connector during its assembly together with said first member (110, 510, 710, 910) and second member (120, 520, 620, 720, 820, 920, 1020).
7. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to any preceding claim, characterized in that it comprises a stamped metal sheet.
8. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to any preceding claim, characterized in that it comprises some thermoplastic or elastomer material.
9. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to any preceding claim, characterized in that the radial thickness of the first part (131 , 531 , 731 , 931) and the radial thickness of the second part (132, 532, 732, 932) are substantially constant.
10. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to claim 9, characterized in that the thickness of the first part (131 , 531 , 731 , 931 ) is substantially equal to the thickness of the second part (132, 532, 732, 932).
11. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to any preceding claim, characterized in that the first part (131 , 531 , 731 , 931 ) and the second part (132, 532, 732, 932) have a non-circular transversal cross section with respect to the axis (X).
12. The connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to claim 11 , characterized in that the non-circular cross sections of the first part (131 , 531 , 731 , 931 ) and the non-circular cross section of the second part (132, 532, 732, 932) are homothetic with respect to the axis (X).
13. The connector according to any preceding claim, characterized in that the first connector surface (131 a, 331a, 531 a, 631a, 731a, 931 a) and the second connector surface (132a, 332a, 532a, 732a, 932a) are substantially parallel.
14. The connector according to any preceding claim, characterized in that the first connector surface (131a, 331a, 531 a, 631a, 731a, 931a) and the second connector surface (132a, 332a, 532a, 732a, 932a) taper along the axis (X) for easing the installation of the connector, so that the first connector surface defines a first tapering angle α with respect to the axis (X), and that the second connector surface defines a second tapering angle β with respect to the axis (X).
15. The connector according to claim 14, characterized in that the first tapering angle α and the second tapering angle β are both greater than 6° for easing the removal of the connector.
16. A unit (100, 200, 500, 600, 700, 800, 900, 1000) comprising the first member (110, 510, 710, 910), the second member (120, 520, 620, 720, 820, 920, 1020) and the connector (130, 230, 330, 530, 630, 730, 830, 930, 1030) according to any of the preceding claim, characterized in that both members and the connector self-center during the assembly of the unit, upon installation of the connector.
17. The unit (100, 200, 500, 600, 700, 800, 900, 1000) according to claim 16, characterized in that it further comprises a detachable locking means
(140, 240, 540, 640, 740, 840, 940, 1040) for securing axially the unit in a reversible manner.
18. The unit (700, 800) according to claim 16 or 17 where: - the first part (731 ) of the connector (730, 830) has a radially inner circumferential surface which defines a third connector surface (731 b),
- the second part (732) of the connector (730, 830) has a radially outer circumferential surface which defines a fourth connector surface (732b), characterized in that it further comprises a stiffener (760) with:
- a radially outer circumferential surface defining a stiffener first surface (761) for mating with said third connector surface (731 b), and - a radially inner circumferential surface defining a stiffener second surface (762) for mating with said fourth connector surface (732b).
19. The unit (700, 800) according to claim 18, characterized in that the stiffener first surface (761 ), the stiffener second surface (762), the connector third surface (731 b) and the connector fourth surface (732b) taper along the longitudinal axis (X).
20. The unit (700, 800) according to claim 18 or 19, characterized in that, on one hand, the connector first surface (731 a), the connector third surface (731 b) and the stiffener first surface (761) are substantially parallel, and that, on the other hand, the connector second surface (732a), the connector fourth surface (732b) and the stiffener second surface (762) are parallel.
21.The unit (700, 800) according to any of the claim 18 to 20, characterized in that the connector (730, 830) and/or the stiffener (760) comprise sensor or indicator means for monitoring operating conditions of the unit and/or external loads applied on the unit and/or ensuring a correct installation of the detachable locking means (740, 840).
22. The unit (100, 200, 500, 600, 700, 800, 900, 1000) according to any of the claim 16 to 21 , characterized in that the unit is a hub-constant velocity joint unit, the first member (110, 510, 710, 910) is a hub or a hub-bearing unit onto which a wheel and a brake rotor are attached, and the second member (120, 520, 620, 720, 820, 920, 1020) is a constant velocity joint or the shaft portion of the bell of a constant velocity joint.
23. The hub-constant velocity joint unit (100, 200, 500, 600, 700, 800, 900, 1000) according to claim 22, characterized in that the detachable locking means (140, 240, 540, 640, 740, 840, 940, 1040) is a nut, a screw or a pin.
24. The hub-constant velocity joint unit (900, 1000) according to claim 22 or 23, characterized in that the radially outer circumferential surface of the first part (931 ) of the connector (930, 1030) defines a wheel spigot (934, 1034) onto which the wheel and the brake rotor are installed. |
A TORQUE TRANSFER UNIT
TECHNICAL FIELD
The invention is related to the transfer of torque between two rotatable mechanical members, in particular between a constant velocity joint and its associated hub for a driven wheel of a motor vehicle.
BACKGROUND
In today's motor vehicles, where the wheel is a safety critical component, the transfer of torque from the driveline, e.g. from a constant velocity joint (CVJ), to the driven wheel, heavily relies upon the mutual engagement of rotating parts machined with splines. Typically, the CVJ has a shaft portion with splines engaging axially corresponding splines of the wheel hub bore.
Known are some attempts made to move away from the typical approach. For instance, it has been proposed in US 4,405,032 to interpose between the CVJ and the hub or the hub-bearing unit a connection element. This connection element can consist of a filler material, which may include a bonding agent incorporating particles of a solid substance such as metal. Alternatively, as described in EP 1 ,666,744, a connection element interposed between the CVJ and the hub-bearing unit can be a tubular metallic piece with a mounting part, the transversal cross-section of which is non-circular and is mounted to a counter part with a corresponding non-circular cross section. This connection element, manufactured for example by means of pressing a metal sheet, can provide additional stiffness to e.g. the bearing onto which it is mounted. It is also proposed in EP 0,653,315 to have a connection element with a flange used to axially pretense the assembly so as to ensure a play-free transmission of the driving torque. There seems to still be room for improvement.
SUMMARY
An object of the invention is to define a method and means according to the method for transmitting a torque between two rotatable members, in particular between a constant velocity joint (CVJ) and a hub or a hub-bearing unit of a driven wheel of a motor vehicle.
Another object of the invention is to define a unit for transmitting a torque between two rotatable members with no axial nor radial nor circumferential play therebetween.
A further object of the invention is to define a unit for transmitting a torque between two rotatable members that is simple and easy to manufacture.
Still, another object of the invention is to define a unit for transmitting a torque between two rotatable members, which unit is easy to assemble and disassemble in case one or more parts needs to be serviced.
The aforementioned objects are achieved according to the invention by a unit for transferring a torque between two members rotatable around a same axis, which unit comprises a connector rotatable around the same axis and which can be made from various materials and shapes.
The aforementioned objects are further achieved according to the invention by a connector which comprises a first part with a first connector surface for mating with the first member, and a second part with a second connector surface for mating with the second member. The first part and the second part of the connector extend substantially axially along the axis, and the radial distance from the first part to the axis is greater than the radial distance from the second part to the axis. The connector further comprises a third part
for interconnecting the first and second parts. Preferably, the mating surfaces have non-circular cross-sections and taper along the axis.
According to the invention, the unit can further comprise a stiffener for easing the installation of the connector and for stiffening the coupling arrangement.
The different enhancements of the connector and the unit comprising the connector according to the invention can be combined in any desired manner as long as no conflicting features are combined.
By providing a method and a unit for transmitting the torque between two rotatable members by means of a connector according to the invention, a plurality of advantages over prior art methods and systems are obtained. A primary purpose of the invention is to provide an improved torque transmission between two rotatable members. This is obtained according to the invention by eliminating the play between the two rotatable members. Consequently, the invention not only ensures a very low wear of components involved in the transmission of the torque, thereby increasing their durability, but also significantly contributes to the reduction of the air-borne noise and vibrations generated during the torque transmission.
The unit for transmitting the torque between two rotatable members according to the invention is easier and cheaper to manufacture, and also easy to assemble and disassemble/dismount. Indeed, the unit comprises a small number of components, and these components have simple geometries, in particular the two rotatable members as well as for the connector which transmits the torque between these two rotatable parts. For instance, splines, which are quite expensive to manufacture, are no longer necessary. Also, the unit for transmitting the torque between the two rotatable members according to the invention is easily serviceable and no special tool is needed to assemble and disassemble the unit.
Other advantages of the invention will become apparent from the detailed description below.
BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail for explanatory, and in no sense limiting, purposes, with reference to the following figures, in which:
Fig. 1 shows the transversal cross-section of a first embodiment of a hub-CVJ unit according to the invention,
Fig. 2 shows the first embodiment of fig. 1 in a perspective view,
Fig. 3 shows the connector of the first embodiment according to the invention,
Fig. 4a-e show several different embodiments of the connector according to the invention,
Fig. 5 shows the transversal cross-section of a second embodiment of a hub-CVJ unit according to the invention,
Fig. 6 shows the second embodiment of fig. 5 in a perspective view,
Fig. 7 shows the transversal cross-section of a third embodiment of a hub-CVJ unit according to the invention,
Fig. 8 shows the third embodiment of fig. 7 in an exploded view,
Fig. 9 shows the transversal cross-section of a fourth embodiment of a hub-CVJ unit according to the invention, and
Fig. 10 shows the fourth embodiment of fig. 9 in an exploded view.
DETAILED DESCRIPTION
In order to clarify the connector and the hub-CVJ unit comprising the connector according to the invention, some examples of its use will now be described in connection with Figures 1 to 10.
Figures 1 to 3 illustrate a first embodiment of the invention. Fig. 1 & fig. 2 illustrate a hub-CVJ unit 100, 200 for the driven wheel of a motor vehicle. The hub-CVJ unit 100, 200, which is rotatable around a longitudinal axis X, comprises a hub 110, which is hollow, a constant velocity joint (CVJ) 120, 220 with a shaft portion 123, and a torque transmitter 130, 230 referred to as a connector. The hub 110 has a hub bore 1 13 for receiving the CVJ shaft 123 during the assembly operation of the hub-CVJ unit 100, 200. The inboard side is the side towards the centre of the vehicle, whereas the outboard side is the side away from the center of the vehicle.
The hub 110 also has a flange 111 , 211 on its outboard side suitable for attaching a wheel (not illustrated) and a brake rotor (not illustrated) for instance by means of bolts (not illustrated) screwed onto the flange 111. Further, the hub 110 presents on its radially outer periphery, a hub bearing portion 112 suitable for installing a bearing onto the hub 110. Alternatively, as illustrated, the hub bearing portion 1 12 constitutes an inner race of the bearing. The hub bore 113 has a hub torque transmission portion 1 16 comprising a radially circumferential inner surface which defines a hub torque transmission surface 117 for the hub 110.
The hub torque transmission portion 116 also has a radially outer circumferential surface which can suitably be used for centering the wheel and the brake rotor with respect to the hub 110. Once the brake rotor and the wheel have been installed onto the radially outer circumferential surface of the hub torque transmission portion 116, they can easily be attached onto the hub flange 111. This way, by making the hub torque transmission portion 116
protruding towards the outboard side of the hub-CVJ unit 100, 200, the hub torque transmission portion 116 can simultaneously function as a wheel spigot 118, 218. Further, the hub bore 113 may present, on its inboard side, a hub centering portion 114 suitable for centering the hub 1 10 with respect to the CVJ 120, 220 during the assembly of the hub-CVJ unit 100, 200.
The hub bore 1 13 may also present a hub free portion 115 located for instance between the hub torque transmission portion 116 and the hub centering portion 114. This hub free portion 115 will be described later on. Further, the hub bore 113 may have a hub shoulder 119 which is preferably perpendicular or substantially perpendicular to the longitudinal axis X, located for instance between the hub free portion 115 and the hub torque transmission portion 116.
The CVJ shaft 123 has a CVJ torque transmission portion 126, the radially outer circumferential surface of which defines a CVJ torque transmission surface 127. The CVJ shaft 123 also has, on its outboard side, a CVJ locking portion 128, 228 suitably with threads onto which a nut 140, 240 can be tightened in order to axially secure the hub-CVJ unit 100, 200. Further, the CVJ shaft 123 may present, on its inboard side, a CVJ centering portion 124 suitable for centering the CVJ 120, 220 with respect to the hub 110 during the assembly of the hub-CVJ unit 100, 200. The CVJ shaft 123 may also present a CVJ free portion 125 located for instance between the CVJ torque transmission surface 127 and the CVJ centering portion 124. This CVJ free portion 125 will be described later on, together with the hub free portion 115 mentioned above.
The connector/torque transmitter 130, 230 is interposed between the hub 110 and the CVJ 120, 220 for fixedly couple these together. The connector 130, 230 comprises two radial parts/portions and may advantageously comprise an optional third part/portion. The two radial portions of the connector 130, 230 are the connector outer portion 131 and the connector inner portion 132.
The connector outer portion 131 is the radially outermost portion of the connector 130, whereas the connector inner portion 132 is the radially innermost portion of the connector 130, 230.
The optional third portion of the connector is the connector wall 133 which connects together the connector outer portion 131 and the connector inner portion 132. The connector wall 133 is advantageously perpendicular or substantially perpendicular to the longitudinal axis X. Advantageously, both the connector outer portion 131 and the connector inner portion 132 extend substantially axially from the connector wall 133 towards its outboard side. This way, the connector outer portion 131 , the connector inner portion 132 and the connector wall 133 delimit a cavity opened towards the outboard side of the hub-CVJ unit 100, 200.
Each of the two radial portions of the connector 130, 230 can have a substantially constant thickness radially, whereas the connector wall 133 can have a substantially constant thickness axially. At least two portions of the connector 130, 230 can have the same thickness.
For manufacturing ease and purposes, the connector 130, 230 is preferably made of a single, solid and annular piece and can advantageously be obtained by stamping or molding. The connector 130, 230 can be made of metal only. Alternatively, the connector 130, 230 can be made of metal and also contain, for sealing, anti-corrosion and vibration damping purposes, a softer material such as a thermoplastic or an elastomer material for example in the form of layers, spots, protrusions or a matrix where the metallic material is embedded or vice versa. The connector 130, 230 can also very well be made of a non-metallic material such as a thermoplastic. Also, the connector 130, 230 can comprise at least one ferrous or non-ferrous material.
The connector outer portion 131 has a radially outer circumferential surface which defines a connector first torque transmission surface 131 a mating with the hub torque transmission surface 117 so that the torque is transmitted between the connector 130, 230 and the hub 110. The connector inner portion 132 has a radially inner circumferential surface which defines a connector second torque transmission surface 132a mating with the CVJ torque transmission surface 127 so that the torque is transmitted between the connector 130, 230 and the CVJ 120, 220. As a result, the torque is transmitted between the hub 110 and the CVJ 120, 220 through the connector 130, 230, thanks only to two pairs of surfaces. The two surfaces of each pair are mating. The first pair of surfaces consists of the hub torque transmission surface 117 and the connector first torque transmission surface 131a, whereas the second pair consists of the CVJ torque transmission surface 127 and the connector second torque transmission surface 132a.
As far as the geometry of these two pairs of surfaces is concerned, it is important to mention, to start with, that the intersection of the two surfaces belonging to the same pair with a transversal plane perpendicular to the longitudinal axis X defines a single matching outline. Therefore, there are two outlines, the first outline which corresponds to the first pair of surfaces, and the second outline which corresponds to the second pair of surfaces.
The figures 3, 4a, 4b, 4c, 4d & 4e illustrate various embodiments of the connector 330, 430a, 430b, 430c, 43Od & 43Oe respectively.
A simple configuration, from a manufacturing point of view, would probably consist of two circular outlines. But this configuration is not wished from a performance point of view because of the high risk of mutual slip between two mating circular surfaces, even when there is an interference fit between them. However, for manufacturing ease and purposes, it is preferable that each outline is somehow symmetrical around the longitunal axis X, and that the center of gravity of each outline is positioned on the longitudinal axis X.
For example, each outline can be a simple square, triangle, or ellipse, as suggested on fig. 3, 4d and 4e. Alternatively, each outline can comprise a succession of straight, circular, convex or concave segments, as suggested on fig. 4a, 4b and 4c.
As illustrated on fig. 3, 4a, 4b and 4c, the two outlines can be homothetic with respect to the longitudinal axis X. That is to say that one outline is obtained by dilatation of the other outline by a constant factor. For example, as illustrated on fig. 3, the first and the second outlines are square. Alternatively, as illustrated on fig. 4d and 4e, the two outlines can be different. For example, as illustrated on fig. 4e, the first outline is square and the second outline is triangular.
With reference now made to fig. 1 , and still concerning the geometry of each of the four surfaces 117, 127, 131 a and 132a which all together ensure an efficient transmission of the torque between the hub 110 and the CVJ 120, in a simple configuration from a manufacturing point of view, these four surfaces could be parallel to the longitudinal axis X. However, in order to facilitate the installation and the removal of the connector 130 between the hub 110 and the CVJ 120, and as best shown on fig. 1 , the four surfaces may advantageously taper along the longitudinal axis X so that, on one hand, the hub torque transmission surface 117 and the connector first torque transmission surface 131 a taper radially inwardly towards the inboard side, so as to define a first tapering angle α with respect to the longitudinal axis X, and, on the other hand, the CVJ torque transmission surface 127 and the connector second torque transmission surface 132a taper radially outwardly towards the inboard side, so as to define a second tapering angle β with respect to the longitudinal axis X. In a particular embodiment of the invention, the absolute values of the first tapering angle α and the second tapering angle β are equal.
It has been observed by the applicant that when α or β is smaller than approximately 6°, it is very difficult to remove the connector 130, and that, the smaller the angle is, the more difficult is gets. However, it has been observed that when α and β are greater than approximately 6°, the removal of the connector is much easier, and, consequently, the disassembly of the hub- CVJ unit 100 too. Therefore, values greater that 6° for both α and for β will advantageously and preferably be chosen.
The assembly of the hub-CVJ unit 100, 200 of fig. 1 and fig. 2 consists of a few and simple steps. At first, the CVJ shaft 123 is introduced into the hub bore 113 so that the CVJ centering portion 124 and the hub centering portion
114, should they be present, engage mutually, with, preferably, a slight radial gap left therebetween in order to easily but accurately center the CVJ 120,
220 with respect to the hub 110. Therefore, the mating surfaces of the CVJ centering portion 124 and the hub centering portion 114 are preferably cylindrical and may be obtained by a simple and cost effective post-forging turning operation, should the CVJ shaft 123 and the hub 110 have been realised by forging. It will be understood by the man skilled in the art that the existence of the above described hub centering portion 114 and CVJ centering portion 124, although easing the assembly of the hub-CVJ unit 100,
200, is optional and can be omitted in order to further reduce the number of manufacturing operations of the hub-CVJ unit 100, 200.
In a second step, the connector 130, 230 is placed from the outboard side between the hub 110 and the CVJ shaft 123. Then, the nut 140, 240 is inserted onto the shaft of the CVJ 120, 220. A washer (not illustrated) can be placed onto the CVJ shaft 123 between the connector 130, 230 and the nut
140, 240. Upon tightening of the nut 140, 240 on the CVJ locking portion
128, 228, the nut 140, 240 pushes the connector 130, 230 which smoothly translates axially towards the inboard side. During this smooth and progressive translation, the connector 130, 230 self-centers, as well as the
CVJ shaft 123 and the hub 110, and interference fit starts to build between
the hub torque transmission surfaces 117 and the connector first torque transmission surface 131a. Simultaneously, interference fit also starts to build between the CVJ torque transmission surface 127 and the connector second torque transmission surface 132a.
The translation of the connector 130, 230 will end when the torque applied on the nut 140, 240 has reached a specified value (as conventionally done when using a dynamometric torque wrench), or, alternatively, when the connector wall 133 of the connector 130, 230 axially comes in contact with the hub shoulder 119. At this point, when the connector 130, 230 has reached its desired position, the axial, radial and circumferential clearances between the hub 110 and the CVJ 120, 220 have been cancelled, and will remain null as long as the nut, or any other equivalent locking means for securing axially the hub-CVJ unit 100, 200, remains in its desired position. Indeed, the two interference fits mentioned above result in a global interference fit between the hub 110 and the CVJ 120, 220 through the connector 130, 230. The build of the global interference between the hub 110 and the CVJ 120, 220 is, thus achieved in an easy, smooth and reliable way.
Alternatively to the nut 140, any other detachable mechanical locking means, for instance a screw, a pin, a seeger ring or a circlip, can be used.
Further, the connector outer portion 131 and the connector inner portion 132 of the connector 130, 230 could advantageously be able to deform, either elastically and/or plastically, during the installation of the connector 130, 230, so as to further improve the mating of, on one hand the hub torque transmission surface 117 with the connector first torque transmission surface 131a, and, on the other hand, the CVJ torque transmission surface 127 with the connector second torque transmission surface 132a.
The connector 130, 230 can deform at a macro level, in the form for instance of a bending of the connector outer portion 131 and the connector inner
portion 132 from the connector wall 133. Also, the connector 330 can present a slit 335 made in at least the connector outer portion 131 or the connector inner portion 132. For instance, as shown on fig. 3, the slit 335 is made parallel to the axis X and through the three portions of the connector 330.
The connector outer portion 131 and the connector inner portion 132 can also deform at a micro level, in the form for instance of material flowing into asperities located on the hub torque transmission surface 117 and the CVJ torque transmission surface 127. This is made possible for instance by making the connector 130, 230 of a material softer than the materials constituting the hub 110 and the CVJ shaft 120, 220. Asperities on the hub torque transmission surface 117 and the CVJ torque transmission surface 127 can be created for instance by submitting the hub torque transmission surface 117 and the CVJ torque transmission surface 127 to a coining operation.
Should the hub 1 10 and the CVJ shaft 120, 220 have been obtained by forging, as conventionally done, and for instance using the near net shape technology, the coining operation or any other post-forging machining operation can be omitted, since a forged part usually present a rough surface with asperities resulting from the forging operation itself. However, a hardening heat treatment operation can be advantageously applied to at least one of the mating surfaces, in order to prevent fretting or lower the risk of fretting between the mating surfaces. Alternatively, or in addition to the hardening heat treatment, a coating, for instance a hard facing coating, can advantageously be applied on at least one of the mating surfaces. Further to the fretting prevention, the coating can also prevent rust formation on the mating surfaces, which rust may render the removal of the connector 130, 230 during the disassembly of the hub-CVJ unit 100, 200 more difficult.
The deformations of the connector outer portion 131 and the connector inner portion 132 can advantageously improve the gripping between the mating
surfaces (two pairs) involved in the torque transmission between the CVJ 120, 220 and the hub 1 10, so that the capacity of this torque transmission is further increased.
As previously mentioned, a more detailed description of the CVJ free portion 125 and the hub free portion 115 follows. Free here has to be understood as free from contact as well as free from post-forging operation. In the hub-CVJ unit 100, 200 assembled as previously described, the hub free portion 115 preferably surrounds the CVJ free portion 125 with a radial gap left therebetween. Therefore, in the case where the hub 110 and the CVJ shaft 120 have been obtained by forging, there is no need for any post-forging machining operation such as turning or grinding of the confronting surfaces of the hub free portion 115 and the CVJ free portion 125. Further, the bigger the radial gap, the lighter the hub 110 and the CVJ 120, 220. Thus, a smaller unsprung mass and a lower fuel consumption of the vehicle are achieved.
Moreover, attention is drawn on the fact that the assembly of the hub-CVJ unit 100 of fig. 1 only requires a simple tool such as a spanner to tighten the nut 140. For the disassembly of the hub-CVJ unit 100, the same spanner can obviously be used to remove the nut 140. Most likely, once the nut 140 has been removed, the interference fits between the connector 130, the hub 110 and the CVJ 120 remain, but can easily be cancelled for instance by axially hitting the outboard end portion of the CVJ shaft 123 with a soft hammer. Thus, there are no special tools needed neither for the assembly nor for the disassembly of the hub-CVJ unit 100.
Figures 5 and 6 illustrate a second embodiment of the invention. A hub-CVJ unit 500, 600 of the second embodiment has many similarities with the hub- CVJ unit 100 of the first embodiment of fig. 1 , but however differs as will be now described. The hub bore 513 present four adjacent portions. Starting from the inboard side and proceeding towards the outboard side, one first find the hub centering portion 514, then the hub torque transmission portion
516, then the hub shoulder 519, and finally the hub free portion 515. The CVJ shaft 523, 623 present four adjacent portions, arranged so that, starting from the inboard side and proceeding towards the outboard side, one first finds the CVJ centering portion 524, 624, then the CVJ torque transmission portion 526, 626, then the CVJ free portion 525, 625, and finally the CVJ locking portion 528, 628. Attention is drawn on the fact that the hub torque transmission portion 516 and the CVJ torque transmission portion 526, 626 are key features of the invention, which is not the case for the hub centering portion 514, the hub free portion 515, the hub shoulder 519, the CVJ centering portion 524, the CVJ free portion 525, nor the CVJ locking portion 528, 628.
The transmission of the torque between the hub 510 and the CVJ 520, 620 still relies upon, on one hand, the mating of the hub torque transmission surface 517 with the connector first torque transmission surface 531 a, and, on the other hand, the mating of the CVJ torque transmission surface 527, 627 with the connector second torque transmission surface 532a.
In order to ease the assembly of the hub-CVJ unit 500, 600 and ensure a good torque transmission capability, the four surfaces just mentioned can advantageously taper radially outwardly along the longitudinal axis X in a direction towards the inboard side. In a particular embodiment of the invention, the first tapering angle α and the second tapering angle β are equal so that the mating surfaces are parallel.
The assembly of the unit 500, 600 can be performed in a simple way. At first, the connector or torque transmitter 530, 630 is placed around the CVJ shaft 523, 623 which is then introduced into the hub bore 513 so that the hub centering portion 514 engages the CVJ centering portion 524, 624. The washer 550, 650 and the nut 540, 640 are then placed onto the CVJ locking portion 528, 628. Upon tightening of the nut 540, 640 on the CVJ locking portion 528, 628, the connector 530, 630 is pulled and smoothly translates
axially towards the outboard side. The translation of the connector 530, 630 will end when the torque applied on the nut 540, 640 has reached a specified value, or alternatively, when the wall 533 of the connector 530, 630 axially comes in contact with the hub shoulder 519.
The hub-CVJ unit 500 of fig. 5 can easily be disassembled, according to the same procedure earlier described for the disassembly of the hub-CVJ unit 100 of fig. 1.
Figures 7 and 8 illustrate a third embodiment of a hub-CVJ unit according to the invention, which differs from the first embodiment of fig.1 by the presence of an additional stiffener or insertion tool 760, 860. The stiffener 760, 860 is, like the connector 730, 830, preferably made of a solid, single, annular and mainly metallic piece. The stiffener 760, 860 is advantageously of a general U-shape. The stiffener 760, 860 has a radially outer surface which defines a stiffener first torque transmission surface 761 , and a radially inner surface which defines a stiffener second torque transmission surface 762. The connector 730, 830, further to the connector first torque transmission surface 731a and the connector second torque transmission surface 732a, has a connector third torque transmission surface 731b and a connector fourth torque transmission surface 732b. The connector third torque transmission surface 731b is the radially innermost surface of the connector outer portion 731 , whereas the connector fourth torque transmission surface 732b is the radially outermost surface of the connector inner portion 732.
The stiffener 760, 860 has mainly two functions. The first one is to ease the installation and removal of the connector 730, 830 between the hub 710 and the CVJ 720, 820. During the assembly of the hub-CVJ unit 700, 800, the stiffener can advantageously be inserted onto the CVJ shaft 723 after the connector 730, 830 but before the nut 740, 840. Upon tightening of the nut 740, 840, the nut 740, 840 comes axially in contact with the stiffener 760, 860 and pushes it towards the inboard side. In turn, the stiffener 760, 860 axially
comes in contact with the connector 730, 830 and pushes it towards the inboard side. During the axial translation of both stiffener 760, 860 and connector 730, 830, four interference fits are simultaneously built. In addition to the two interference fits occurring during the assembly of the hub-CVJ unit 100 of fig.1 , two new interference fits are built. That is to say : a first one between the stiffener first torque transmission surface 761 and the connector third torque transmission surface 731 b, a second one between the stiffener second torque transmission surface 762 and the connector fourth torque transmission surface 732b, a third one between the connector first torque transmission surface 731 a and the hub torque transmission surface 717, and a fourth one between the connector second torque transmission surface 732a and the CVJ torque transmission surface 727, 827.
Advantageously, the stiffener first torque transmission surface 761 and the connector third torque transmission surface 731b can taper along the longitudinal axis X and radially inwardly towards the inboard side, in a similar way as the connector first torque transmission surface 731 and the hub torque transmission surface 717, 817 can. Advantageously also, the stiffener second torque transmission surface 762 and the connector fourth torque transmission surface 732b can taper along the longitudinal axis X and radially outwardly towards the inboard side, in a similar way as the connector second torque transmission surface 732a and the CVJ torque transmission surface 727, 827 can.
The eight surfaces just mentioned contribute all together in the transmission of the torque within the hub-CVJ unit 700 of fig. 7. In the hub-CVJ unit 100 of fig. 1 , the transmission of the torque relied upon four surfaces. In the hub- CVJ unit 700 of fig. 7, the transmission of the torque relies upon four more surfaces which, advantageously, allow assembling and dismounting of the hub-CVJ unit 700 in an even smoother, more progressive and more reliable way. Still, no special tools are needed for the installation and dismounting of
the hub-CVJ unit 700. For instance, a span and a soft hammer may be sufficient.
With reference now made to figure 7, the second function of the stiffener 760 is to stiffen the coupling arrangement between the hub 710 and the CVJ 720. By filling the cavity delimited by the connector outer portion 731 , the connector inner portion 732 and the connector wall 733, the stiffener 760 prevents the connector outer portion 731 to deform radially inwardly and the connector inner portion 732 to deform radially outwardly during the installation of the connector 730 and/or during the transmission of the torque within the hub-CVJ unit 700. This prevention ensures an efficient and safe torque transmission and can even allow for a higher torque to be transmitted within the hub-CVJ unit 700, hence from the engine to the driven wheels of the vehicle.
Further, the stiffener 760 may include sensor or indicator means (not illustrated) suitable for monitoring for instance the operating condition of the hub-CVJ unit 700 (e.g. temperature, vibration, ...) or the loads applied by the ground on the wheel. The sensor or indicator means may also be used to apply a correct tightening torque on the nut 740 during the assembly of the hub-CVJ unit 700.
In another embodiment, not illustrated, the stiffener 760 and the connector 730 may advantageously be united so as to form a single piece.
Figures 9 and 10 illustrate a fourth preferred embodiment of the invention. This fourth embodiment differs from the first embodiment of fig. 1 as will now be explained. In the hub-CVJ unit 900, 1000, the hub torque transmission surface 917 is not located in the hub bore 913, but on a radially outer portion of the hub 910 adjacent to the hub flange 911. Also, the connector first torque transmission surface 931 a which mates with the hub torque transmission surface 917, 1017 is not the radially outer surface of the
connector outer portion 931 , but its radially inner surface instead. It is therefore more appropriate to say that in the hub-CVJ unit 900, 1000, the connector 930, 1030 is mounted onto the hub 910 and CVJ 920, 1020, rather than between the hub 910 and the CVJ 920, 1020.
The connector outer portion 931 extends substantially axially from the connector wall 933 towards the inboard side, whereas, on the contrary, the connector inner portion 932 extends substantially axially from the connector wall 933 towards the outboard side. Also, the hub shoulder 919 is an outboard side face of the hub 910. The connector wall 933 may rest against the hub shoulder 919 once the hub-CVJ unit 900, 1000 has been assembled for instance by tightening the nut 940, 1040 against the washer 950, 1050. Moreover, the connector outer portion 931 is the wheel spigot 934, 1034 onto which the wheel and the brake rotor can suitably be installed before their attachment onto the hub flange 911.
For the above reasons, the geometry of the hub 910 is further simplified with respect to the hubs of the previous embodiments, which brings further advantages as far as manufacturability and costs are concerned. To end with, the tapering, along the longitudinal axis X and radially outwardly towards the inboard side, of the four surfaces 917, 931 a, 927 and 932a involved in the torque transmission between the hub 910 and the CVJ 920, 1020 can allow an easy installation of the connector 930, 1030 and the assembly of the unit 900, 1000 for the same reasons as previously mentioned.
Assembly and disassembly of the unit 900, 1000 of the fourth embodiment can be performed in the same simple and easy way as for the previous embodiments.
The invention is not restricted to the above-described embodiments, but may be varied within the scope of the following claims.
24 JULY 2007
FIGURE 1 shows the transversal cross-section of the first embodiment of a hub - constant velocity joint (CVJ) unit according to the invention,
X longitudinal axis, α first tapering angle, β second tapering angle,
100 hub-CVJ unit,
110 hub,
11 1 hub flange,
112 hub bearing portion, 113 hub bore,
114 hub centering portion,
115 hub free portion,
116 hub torque transmission portion,
117 hub torque transmission surface, 118 wheel spigot,
119 hub shoulder,
120 constant velocity joint (CVJ),
123 CVJ shaft,
124 CVJ centering portion, 125 CVJ free portion,
126 CVJ torque transmission portion,
127 CVJ torque transmission surface,
128 CVJ locking portion, 130 connector, 131 connector outer portion,
131a connector first torque transmission surface,
132 connector inner portion,
132a connector second torque transmission surface, 133 connector wall,
140 nut.
FIGURE 2 shows the hub-CVJ unit of fig. 1 in a perspective view,
200 hub-CVJ unit,
21 1 hub flange,
218 wheel spigot,
228 CVJ locking portion, 230 connector,
240 nut.
FIGURES 3 shows the connector of the hub-CVJ unit of fig.1 according to the invention, X longitudinal axis,
330 connector,
331 a connector first torque transmission surface, 332a connector second torque transmission surface. 335 slit.
FIGURES 4a, 4b, 4c, 4d & 4e show various embodiments of the connector of the hub-CVJ unit of fig. 1 according to the invention.
FIGURE 5 shows the transversal cross-section of a second embodiment of a hub-CVJ unit according to the invention, 500 hub-CVJ unit,
X longitudinal axis,
510 hub,
511 hub flange, 512 hub bearing portion,
513 hub bore,
514 hub centering portion,
515 hub free portion,
516 hub torque transmission portion,
517 hub torque transmission surface,
518 wheel spigot, 519 hub shoulder,
520 CVJ,
523 CVJ shaft,
524 CVJ centering portion,
525 CVJ free portion, 526 CVJ torque transmission portion,
527 CVJ torque transmission surface,
528 CVJ locking portion,
530 connector,
531 connector outer portion, 531 a connector first torque transmission surface,
532 connector inner portion,
532a connector second torque transmission surface,
533 connector wall, 540 nut, 550 washer.
FIGURE 6 shows the hub-CVJ unit of fig. 5 according to the invention in an exploded view,
600 hub-CVJ unit,
X longitudinal axis,
611 hub flange,
620 CVJ,
623 CVJ shaft,
624 CVJ centering portion,
625 CVJ free portion,
626 CVJ torque transmission portion,
627 CVJ torque transmission surface,
628 CVJ locking portion,
630 connector,
631 a connector first torque transmission surface, 640 nut, 650 washer.
FIGURE 7 shows the transversal cross-section of a third embodiment of a hub-
CVJ unit according to the invention,
700 hub-CVJ unit, 710 hub,
717 hub torque transmission surface,
720 CVJ,
723 CVJ shaft,
727 CVJ torque transmission surface, 728 CVJ locking portion,
730 connector,
731 connector outer portion,
731a connector first torque transmission surface,
731 b connector third torque transmission surface 732 connector inner portion,
732a connector second torque transmission surface,
732b connector fourth torque transmission surface,
733 connector wall,
740 nut, 760 stiffener,
761 stiffener first torque transmission surface,
762 stiffener second torque transmission surface.
FIGURE 8 shows the hub-CVJ unit of fig. 7 according to the invention in an exploded view,
800 hub-CVJ unit,
811 hub flange,
817 hub torque transmission surface,
820 CVJ,
824 CVJ centering portion,
825 CVJ free portion, 827 CVJ torque transmission surface,
830 connector,
840 nut,
860 stiffener.
FIGURE 9 shows the transversal cross-section of a fourth embodiment of a hub-CVJ unit according to the invention,
900 hub-CVJ unit,
X longitudinal axis,
910 hub, 911 hub flange,
912 hub bearing portion,
913 hub bore,
914 hub centering portion,
915 hub free portion, 916 hub torque transmission portion,
917 hub torque transmission surface,
919 hub shoulder,
920 constant velocity joint (CVJ), 923 CVJ shaft, 924 CVJ centering portion,
925 CVJ free portion,
926 CVJ torque transmission portion,
927 CVJ torque transmission surface,
928 CVJ locking portion, 930 connector,
931 connector outer portion,
931 a connector first torque transmission surface,
932 connector inner portion,
932a connector second torque transmission surface,
933 connector wall,
934 wheel spigot, 940 nut,
950 washer.
FIGURE 10 shows the hub-CVJ unit of fig. 9 according to the invention in an exploded view,
1000 hub-CVJ unit,
1011 hub flange,
1017 hub torque transmission surface,
1020 CVJ,
1024 CVJ centering portion,
1025 CVJ free portion,
1027 CVJ torque transmission surface,
1028 CVJ locking portion,
1030 connector,
1034 wheel spigot,
1040 nut,
1050 washer.