CN117662682A - Spline self-locking assembly for dual-mass flywheel - Google Patents

Abstract

The present disclosure relates to a spline shaft self-locking assembly for a dual mass flywheel and a dual mass flywheel including the same. The dual mass flywheel comprises a secondary mass body comprising a hub with internal spline teeth for cooperation with a spline shaft of a next stage transmission, the spline shaft self-locking assembly comprising a self-locking hub mounted on the secondary mass body of the dual mass flywheel and comprising a central bore concentric with the hub of the dual mass flywheel, the central bore being provided with internal spline teeth, the self-locking hub being resiliently biased such that the internal spline teeth of the self-locking hub are offset from the internal spline teeth of the hub of the secondary mass body by a predetermined angle in a circumferential first direction. By utilizing the method and the device, the gap between the internal spline teeth of the primary and secondary mass bodies and the spline teeth of the spline shaft is eliminated, so that the problems of noise and part service life caused by collision between the spline teeth during low-speed rotation or fluctuation are avoided.

Description

Spline self-locking assembly for dual-mass flywheel

Technical Field

The present disclosure relates to the construction of dual mass flywheels, and more particularly to a spline self-locking assembly for self-locking a spline shaft mated with a dual mass flywheel.

Background

Typically, a flywheel is provided at the rear end of the engine of the vehicle to mitigate torsional vibrations of the driveline due to engine rotation imbalance. The flywheel is conventionally made of cast steel, for example, and has a certain mass, and is bolted to the rear end face of the crankshaft of the engine, and is provided with teeth on its outer periphery to mesh with a starter gear, driving the crankshaft into rotation. The flywheel functions not only at the time of engine start, but also stores and releases energy after engine start to improve uniformity of engine operation while transmitting engine power to the clutch.

However, such a conventional flywheel has a limitation that the natural frequency between the engine and the transmission cannot be lowered below the idle rotation speed, that the possibility of resonance at the idle rotation speed cannot be avoided, and in addition, since the torsional damper is provided in the clutch, the spring rate of the damper cannot be lowered and the damping effect is poor, and for this reason, in recent years, a Dual Mass Flywheel (DMF) has been proposed. A dual mass flywheel generally includes a primary mass body which remains in place on one side of the original engine and functions as an original flywheel for starting and transmitting rotational torque of the engine, and a secondary mass body for improving rotational inertia of the transmission, with an annular chamber provided between the primary mass body and the secondary mass body, and a spring damper provided in the annular chamber to connect the two mass bodies as a unit.

The spring damper is connected on the one hand to the primary mass and on the other hand to a drive disk, which is fastened to the secondary mass. The secondary mass is usually connected to the input shaft of the next-stage transmission, for example, a transmission or clutch, which input shaft is usually in the form of a spline, for which purpose the secondary mass is provided with a hub provided with internally splined teeth, whereby the input shaft of the transmission or clutch is inserted into the hub and forms a rotary connection.

For assembly and manufacturing reasons, there is usually a certain clearance between the internal spline of the hub and the spline shaft of the input shaft when the two are matched, which can ensure that the spline shaft is easy to insert into the internal spline hole of the hub during assembly, but the clearance can cause a certain problem, for example, when the engine rotates at a low speed or changes or fluctuates, the clearance can cause collision between the spline teeth of the spline shaft and the internal spline teeth of the hub, thereby causing unpleasant noise. In addition, such collisions can also adversely affect the life of the spline teeth. Although the clearance can be reduced by reducing the fit tolerance of the spline teeth, the reduction in fit tolerance leads to an increase in processing costs and brings about difficulty in assembly.

Thus, there is a need for an improved dual mass flywheel to eliminate the above-mentioned problems.

Disclosure of Invention

The present invention has been made to solve the above-mentioned problems occurring in the prior art, and provides a spline shaft self-locking assembly by which a gap generated when spline teeth of a spline shaft are engaged with a hub of a dual mass flywheel can be eliminated, and thus noise due to the gap, for example, when an engine rotates at a low speed can be eliminated.

According to the present invention there is provided a spline shaft self-locking assembly for a dual mass flywheel comprising a secondary mass body comprising a hub with internal spline teeth for cooperation with a spline shaft of a next stage transmission, the spline shaft self-locking assembly comprising a self-locking hub mounted on the secondary mass body of the dual mass flywheel and comprising a central bore concentric with the hub of the dual mass flywheel, the central bore being provided with internal spline teeth, the self-locking hub being resiliently biased such that the internal spline teeth of the self-locking hub are offset from the internal spline teeth of the hub of the secondary mass body in a first direction circumferentially by a predetermined angle, preferably in the range 0.2 to 1 degrees, more preferably in the range 0.4 to 0.8 degrees.

The self-locking hub is arranged on the hub of the secondary mass body, and is elastically biased to enable the inner spline teeth of the self-locking hub to be staggered with the inner spline teeth of the hub of the secondary mass body, when the spline shaft is inserted, the inner spline teeth of the self-locking hub are abutted against the spline teeth of the spline shaft by means of elastic bias, so that gaps between the inner spline teeth of the primary secondary mass body and the spline teeth of the spline shaft are eliminated, and noise and part life problems caused by collision between the spline teeth during rotation, particularly low-speed rotation, are avoided.

Preferably, the self-locking hub is made of wear-resistant alloy steel.

In one embodiment, a spring is included, for example, disposed between the recess of the secondary mass and the opening of the self-locking hub to bias the self-locking hub. Preferably, a plurality of springs are provided at equal intervals along the circumferential direction of the secondary mass body so as to uniformly apply the biasing force to the self-locking hub, but the present application is not limited thereto.

In one embodiment, a dust cap is also included, secured to the secondary mass, such as by rivets, welding, or the like, thereby sandwiching the self-locking hub and spring between the dust cap and secondary mass, axially restricting movement of the self-locking hub and spring.

In one embodiment, a stop finger is provided in the peripheral portion of the dust cap, for example bent at right angles from the dust cap, the peripheral edge of the self-locking hub being provided with a recess into which the stop finger is inserted, thereby limiting the range of rotation of the self-locking hub in the circumferential direction.

Preferably, the stop finger abuts one end of the recess, thereby limiting further rotation of the self-locking hub in the circumferential first direction, and the spring is preloaded when the stop finger abuts the one end of the recess. The preload is, for example, precompression.

Preferably, the internal spline teeth of the self-locking hub are offset from the internal spline teeth of the hub of the secondary mass by an angle within the predetermined range when the stop finger abuts the one end of the recess.

Thereby, when the spline shaft of the next stage transmission is inserted into the hub of the secondary mass, the spline teeth of the spline shaft push the self-locking hub against the biasing force of the spring in a second direction opposite to the first direction, and the self-locking hub abuts against the spline teeth of the spline shaft under the biasing force of the spring, thereby eliminating the gap between the spline teeth of the spline shaft and the inner spline teeth of the hub of the secondary mass.

In one embodiment, the spring and dust cap may be omitted, and the self-locking hub includes resilient arms at its outer periphery that impart a resilient bias to the self-locking hub.

The spring arm is preferably formed by cutting at the outer periphery of the self-locking hub and its free end is fixed to the secondary mass, for example by means of rivets. Thereby, the internal spline teeth of the self-locking hub are offset from the internal spline teeth of the hub of the secondary mass by a predetermined angle in a first circumferential direction by means of the elasticity of the spring arms.

The elastic biasing and dislocation are realized by utilizing the self-locking hub to form the elastic arm, so that the addition of a separate spring part can be avoided, and the improvement on the existing secondary mass body and the dust cover is omitted, thereby facilitating the transformation of the existing dual-mass flywheel, simplifying the part inventory and production management and reducing the cost.

As described above, according to the present application, by providing the self-locking hub such that the internal spline teeth of the self-locking hub are elastically staggered from the internal spline teeth of the hub of the secondary mass body by a predetermined angle, thereby, when engaged with the spline shaft of the next stage transmission, although there is a gap between the spline teeth of the spline shaft and the internal spline teeth of the hub of the secondary mass body, since the self-locking hub is elastically biased by the spring or the elastic arm against the spline teeth of the spline shaft, the gap is eliminated, and in particular, at the time of engine low speed operation, the gap is avoided from causing collision between the splines, and thereby noise and damage to parts due to collision are avoided, and the part life is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic cross-sectional view illustrating a dual mass flywheel including a self-locking hub according to the present application;

FIG. 2 is a schematic diagram illustrating the dual mass flywheel of FIG. 1 as seen from the axial side;

FIG. 3A is a cross-sectional view showing line A-A of FIG. 2

Fig. 3B to 3D are partial enlarged views showing the views B to D;

fig. 4 is a perspective view showing a dust cap;

fig. 5 is a perspective view showing a secondary mass;

FIG. 6 is a perspective view showing the self-locking hub;

FIG. 7 is a schematic cross-sectional view illustrating a dual mass flywheel according to a variation of the present application; and

fig. 8A is a schematic view showing the self-locking hub in fig. 7, and fig. 8B is a sectional view taken along line A-A of fig. 8A.

Detailed Description

Embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Throughout the drawings, like reference numerals designate like elements or features.

Thus, the following detailed description of the embodiments of the invention, as presented in conjunction with the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In the description of the present invention, it is to be understood that the term "circumferential" or "rotational direction" refers to the circumferential direction or rotational direction of the modified feature, the term "axial" refers to the direction about which the modified feature rotates, and the term "radial" refers to the direction perpendicular to the "axial" unless otherwise specifically defined, these directions are all directions as would be conventionally understood by a person skilled in the art. Additionally, directional terms "upper", "lower", "inner", "outer", etc. indicate an orientation or positional relationship based on that shown in the drawings, or an orientation or positional relationship that is conventionally put in place when the inventive product is used, or an orientation or positional relationship that is conventionally understood by those skilled in the art, merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus are not to be construed as limiting the invention. Further, it is also to be understood that in describing the present invention, the term "connected" includes not only a direct connection of one element, component or feature to another element, component or feature, but also an indirect connection of one element, component or feature to another element, component or feature via an intervening element, component or feature. The word "directly connected" does not include the intervening elements.

Since the present disclosure is primarily directed to spline shaft self-locking assemblies for dual mass flywheels, it is not the point of the present disclosure that it is for dual mass flywheels themselves, and therefore, will not be described in detail in this disclosure. In addition, while the technical solution of the present disclosure has been described in the present disclosure by taking a dual mass flywheel as an example, it is to be understood that the present disclosure is not limited thereto, but may be applied to other similar devices for eliminating a gap between a spline shaft and a spline hub.

According to the present application, in a dual mass flywheel, in particular, a self-locking hub is provided on a secondary mass of the dual mass flywheel, which is spring biased, whereby the self-locking hub can be rotated elastically within a predetermined angular range concentric with the secondary mass, which self-locking hub can be provided with internal spline teeth of the same specification as the internal spline teeth of the hub of the secondary mass, and under the effect of the spring bias, the internal spline teeth of the self-locking hub are slightly offset in circumferential direction from the internal spline teeth of the hub of the secondary mass, which is typically in the range of 0.2 to 1 degree, and preferably in the range of 0.4 to 0.8 degree, and which self-locking hub is spring biased to this offset state, so that upon insertion of a mating spline shaft, the internal spline teeth of the self-locking hub can be spring biased against the spline teeth of the spline shaft, whereby the clearance between the spline teeth of the spline shaft and the internal spline teeth of the hub of the secondary mass is eliminated, thereby overcoming the problems encountered in the prior art.

Detailed description of embodiments of the present disclosure will be made with reference to the accompanying drawings, in which fig. 1 shows a partial cross-sectional view of a dual mass flywheel incorporating aspects of the present disclosure.

As shown in fig. 1, the dual mass flywheel 1 includes a primary mass body 3, a secondary mass body 4 rotatably connected to the primary mass body by means of a buffer member such as a spring. Referring to fig. 5, the secondary mass 4 includes a main body 41, a hub 42 is formed at the center of the main body 41, and the hub 42 is generally formed with an internal spline 43 so as to be connected with an input shaft 51 of a next-stage device 5, for example, a transmission or clutch. The input shaft 51 is typically formed with external splines at the connection end, the connection of which is achieved by inserting the externally splined portion of the input shaft 51 into the internal spline 43 of the hub.

It will be appreciated that a shoulder (not shown) may be formed on the input shaft to define the axial location at which the spline shaft 51 is inserted into the hub 42.

With further reference to fig. 2, a self-locking assembly 6 is provided on one axial side on the secondary mass 110, which self-locking assembly 6 comprises a self-locking hub 61, which self-locking hub 6 is mounted coaxially with the secondary mass 4 and is rotatable relative to the secondary mass 4 about the axis of rotation X of the secondary mass 4 within a predetermined range. Referring to fig. 6 in combination, the self-locking hub 61 is formed with a hole 62, 62 in its centre, with internal teeth or splines 63, which internal teeth or splines 63 are identical to the internal splines 43 of the hub of the secondary mass 4. Thus, when the spline shaft 51 of the next stage device is inserted, the spline teeth of the spline shaft 51 are also engaged with the internal spline of the self-locking assembly 6.

In order to ensure that the self-locking boss 61 is coaxial with the secondary mass body 4, a boss 421 (see fig. 3A) is formed protruding from the boss 42 of the secondary mass body 4, and a recess 64 (see fig. 3A) is formed on the self-locking boss 61, and when assembled, the recess is snapped onto the boss, and the self-locking boss 61 is ensured to rotate around the boss 421 by the cooperation of the recess and the boss, and thus to be coaxial with the secondary mass body 4. The pit may be formed by stamping, casting, etc., and the present disclosure is not limited to any particular method. Specifically, the self-locking hub 61 includes an outer peripheral portion 65 and a central portion 66 axially offset from the outer peripheral portion, the above-described centering recess 64 is formed by means of offset between the outer peripheral portion and the central portion, and the hole 62 is formed in the central portion such that the outer peripheral portion, the central portion, and the hole 62 are concentric.

The self-locking hub 61 may be made of a wear resistant material, such as alloy steel, but the application is not limited thereto.

On the radially outer side of the hub of the secondary mass body 4, a plurality of grooves 44 are formed along the circumferential direction of the secondary mass body 4, and the grooves 44 may be formed in the body of the secondary mass body 41 by machining, for example, but the present disclosure is not limited thereto. As shown in fig. 2, four grooves 44 are formed at equal intervals along the circumferential direction, but the present disclosure is not limited thereto, and more or less than four, for example, two, three, are within the scope of the present disclosure. In view of the stress balance, it is preferable that the plurality of grooves are uniformly arranged in the circumferential direction, but the present disclosure is not limited thereto.

At the radial position of the self-locking hub 61, in particular, at a position corresponding to the grooves 44 of the secondary mass 4 in the outer circumferential portion, openings 67 are provided, the number of openings 67 corresponding to the number of grooves 44, whereby the circumferential dimension of the openings 67 is preferably equal to the circumferential dimension of the grooves 44 when the self-locking hub 61 is mounted on the secondary mass 4. The spring 7 is arranged in the groove 44 and one end of the spring 7 abuts against one circumferential end of the groove 44 and the other end against one circumferential end of the opening 67, whereby the spring 7 biases the self-locking hub 61 in a circumferential first direction (e.g. anticlockwise in the figure) such that the spline teeth of the self-locking hub 61 are offset from the spline teeth of the hub of the secondary mass by a predetermined angle a, see fig. 3B, which may be in the range of 0.2 to 1 degrees, preferably in the range of 0.4 to 0.8 degrees. As shown in fig. 2, the spring 7 is a cylindrical coil spring having a free length substantially equal to the circumferential dimension of the opening 67 in the present embodiment, but the present disclosure is not limited thereto, and may take other types of springs or force-receiving forms.

A dust cap 8 is also provided in the axial direction, which dust cap 8 may be a dust cap on a secondary mass in a conventional dual mass flywheel, but the structure is improved.

Referring to fig. 4 in combination, the dust cap 140 is secured to the secondary mass by riveting, bolting, welding, or the like. Preferably, the dust cap 8 is substantially annular in shape with a central aperture 81 thereof sized to allow a central portion of the self-locking hub 61 to emerge from the central aperture, while the dust cap 8 axially abuts against an outer peripheral portion of the self-locking hub 61, thereby limiting movement of the self-locking hub 61 in an axial direction, such that the self-locking hub 61 is rotatable only within a predetermined range, but not axially movable, by the dust cap 8.

At a predetermined radial position of the dust cap 8, a recess 82 is also formed which cooperates with the recess 44 of the secondary mass for receiving the spring 7, thereby restraining the spring 7 in place and preventing the spring 7 from falling.

In one embodiment, in order to limit the rotation range of the self-locking hub 61, a plurality of notches 68 are formed at the periphery of the outer peripheral portion of the self-locking hub 61, and at corresponding positions, a plurality of stopper fingers 83 are formed on the dust cover 8, and the stopper fingers 83 are bent from the dust cover 8, for example, at right angles and inserted into the notches 68, see fig. 3D, thereby limiting the rotation of the self-locking hub 61 within a predetermined range.

As shown in fig. 3B, fig. 3B shows the misalignment between the internal spline teeth of the self-locking hub 61 and the internal spline teeth of the hub of the secondary mass body when the spline shaft is not inserted into the dual mass flywheel, which, as described above, is preferably in the range of 0.2 to 1 degrees, preferably in the range of 0.4 to 0.8 degrees. At this time, the spring 7 is compressed between the opening of the self-locking hub and the groove of the secondary mass, thereby giving the self-locking hub 61 a preload, and at this time the stop finger 83 of the dust cover 8 abuts against one end in the circumferential direction of the recess 68 of the self-locking hub 61, preventing the self-locking hub 61 from continuing to rotate in that direction (clockwise in fig. 2), but allowing the self-locking hub 61 to rotate in the counterclockwise direction by the predetermined range.

Thus, when the spline shaft of the next stage transmission is inserted into the hub of the secondary mass body, the spline of the spline shaft pushes away the self-locking hub 61 against the bias of the spring 7 during the insertion, and after the insertion is in place, the internal spline of the self-locking hub 61 abuts against the external spline of the spline shaft by means of the biasing force of the spring 7, thereby eliminating the clearance between the external spline of the spline shaft and the internal spline of the hub of the secondary mass body, avoiding noise generated by collision between the external spline of the spline shaft and the internal spline of the secondary mass body, for example, at low engine speed or speed fluctuation, and improving the working load of the spline shaft and the hub, and improving the life of the spline shaft and the hub.

In addition, in the present embodiment, the addition of the self-locking hub 61 is accommodated by modification to the existing secondary mass and dust cap, thereby allowing the existing dual mass flywheel to be easily retrofitted without having to prepare excessive new parts, simplifying inventory management and reducing costs.

A modification of the above-described embodiment is described below with reference to fig. 7 to 8B.

In the embodiment shown in fig. 7, the self-locking hub 61' and the spring 7' are integrally formed, the self-locking hub 61' being formed of, for example, wear-resistant alloy steel. As shown in fig. 7, the self-locking hub 61' is generally circular in shape and comprises a central bore with internal splines 63' which are identical to the internal splines of the hub of the secondary mass 4, but which, when assembled, the internal spline teeth of the self-locking hub 61' are offset from the internal spline teeth of the hub of the secondary mass 4 by a predetermined angle, for example in the range 0.2 to 1 degrees, preferably in the range 0.4 to 0.8 degrees, as described above.

The difference from the embodiment shown above with reference to fig. 1 to 6 is that in the embodiment of fig. 7 no separate spring 7 is included. As shown in fig. 7, the outer peripheral portion of the self-locking hub 61' forms a resilient arm 7' in the circumferential direction, and the resilient arm 7' functions as a spring. For example, the resilient arms 7' may be formed by wire cutting, laser cutting, stamping, or other means as would occur to one skilled in the art. The free end of the resilient arm 7' (the end not fixed to the central part of the self-locking hub) is fixed to the secondary mass 4, for example by one of any means conceivable to a person skilled in the art, such as rivets, screws, adhesive bonding, welding etc., and when assembled in place the resilient arm 7' causes the internal spline teeth of the self-locking hub 61' to be displaced from the internal spline teeth of the hub of the secondary mass by a predetermined angle.

The resilient arms 7' may be formed along the periphery of the self-locking hub and may comprise a plurality of resilient arms evenly distributed along the circumference of the self-locking hub so as to provide a balanced biasing force. In addition, the elastic arm 130 'may also have a reduced cross-section portion or a shape change portion, such as a cross-section thinned portion or a curved shape portion, to adjust the elastic coefficient of the elastic arm 7'.

Although in the embodiment of fig. 8A and 8B, an embodiment is described in which the resilient arms are disposed along the circumference of the self-locking hub, the resilient arms may be disposed in other manners, such as in a radial manner, or other oblique directions, and the present application is not limited thereto.

When the spline shaft of the next stage transmission is inserted, the spline teeth of the spline shaft push the internal spline teeth of the self-locking hub 61', and after complete insertion, the internal spline teeth of the self-locking hub 61' abut against the spline teeth of the spline shaft by means of the elastic restoring force of the elastic arm 7', thereby eliminating the clearance between the spline teeth of the spline shaft and the internal spline teeth of the secondary mass body, and avoiding noise and life effects due to collision between the spline teeth when the engine rotates at a low speed, for example.

In the embodiment shown in fig. 7 and 8, by integrating the spring 7 'with the self-locking hub 61' and by fixing the self-locking hub 61 'concentrically with the secondary mass to the secondary mass by means of the resilient arms 7', the need for a separate spring is eliminated, and the dust cover can also be used with existing dust covers, the secondary mass and dust cover do not have to be modified, simplifying the overall structure, adapting to retrofit existing dual mass flywheels, simplifying stock spare part management.

Accordingly, while the present invention has been described above by referring to the embodiments thereof, it should be understood that the present invention is not limited to the examples described above, but various modifications or variations can be made within the scope defined in the appended claims. For example, in the above description, although the self-locking hub forms an internal spline of the same specification as the internal spline of the secondary mass, it is understood that the self-locking hub need not form a complete ring of spline teeth, but may form only a portion of the teeth, so long as the specifications of the teeth, for example the teeth shape, are the same as the specifications of the teeth of the internal spline of the secondary mass, so that the internal spline teeth of the self-locking hub can mate with the spline shaft, and the teeth may be spaced apart, or may be formed on only a portion of the circumference, for example on a quarter of the circumference, for which the present application is not limited. The scope of the invention is not to be limited by the embodiments described above, but by the appended claims and their equivalents.

Claims (15)

1. A spline shaft self-locking assembly for a dual mass flywheel comprising a secondary mass body including a hub having internal spline teeth for cooperation with a spline shaft of a next stage transmission, wherein the spline shaft self-locking assembly comprises a self-locking hub mounted on the secondary mass body of the dual mass flywheel and comprising a central bore concentric with the hub of the dual mass flywheel, the central bore being provided with internal spline teeth, the self-locking hub being resiliently biased such that the internal spline teeth of the self-locking hub are offset from the internal spline teeth of the hub of the secondary mass body by a predetermined angle in a circumferential first direction.

2. The spline shaft self locking assembly of claim 1, wherein the angle is in the range of 0.2 degrees to 1 degree, preferably in the range of 0.4 to 0.8 degrees.

3. The spline shaft self-locking assembly of claim 1 or 2, wherein the self-locking hub is made of wear resistant alloy steel.

4. A spline shaft self-locking assembly according to any one of claims 1 to 3, further comprising a spring biasing said self-locking hub.

5. The spline shaft self-locking assembly of claim 4, wherein the spring is a coil spring disposed between the recess of the secondary mass and the opening of the self-locking hub to bias the self-locking hub.

6. The spline shaft self locking assembly of claim 5, wherein said springs are equally spaced apart along the circumference of the secondary mass.

7. The spline shaft self-locking assembly of any one of claims 1 to 6, further comprising a dust cover secured to the secondary mass, thereby sandwiching the self-locking hub and spring between the dust cover and the secondary mass.

8. The spline shaft self-locking assembly of claim 7, wherein a stop finger is provided in an outer peripheral portion of the dust cover, and an outer peripheral edge of the self-locking hub is provided with a recess into which the stop finger is inserted, thereby limiting a range of rotation of the self-locking hub in a circumferential direction.

9. The spline shaft self locking assembly of claim 8, wherein said stop finger abuts an end of said notch, thereby limiting continued rotation of said self locking hub in said circumferential first direction, and said spring is preloaded when said stop finger abuts said end of said notch.

10. The spline shaft self-locking assembly of claim 9, wherein the internal spline teeth of the self-locking hub are offset from the internal spline teeth of the hub of the secondary mass by an angle within the predetermined range when the stop finger abuts the one end of the recess.

11. A spline shaft self-locking assembly according to any one of claims 1 to 3, wherein said self-locking hub includes a resilient arm at its outer periphery, said resilient arm imparting a resilient bias to said self-locking hub.

12. The spline shaft self-locking assembly of claim 11, wherein said spring arm is formed by cutting at an outer periphery of said self-locking hub and a free end of the spring arm is secured to a secondary mass.

13. The spline shaft self-locking assembly of claim 11 or 12, wherein comprising a plurality of spring arms equally spaced circumferentially about such that the self-locking hub is disposed concentric with the secondary mass.

14. The spline shaft self locking assembly of any one of claims 11 to 13, wherein said spring arm includes a resilient change therein.

15. A dual mass flywheel, wherein the dual mass flywheel comprises a spline shaft self-locking assembly as claimed in any one of claims 1 to 14.