GB2612103A

GB2612103A - Rotating shaft coupling

Info

Publication number: GB2612103A
Application number: GB2115207.9A
Authority: GB
Inventors: Boyd John; Atkinson James
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2021-10-22
Filing date: 2021-10-22
Publication date: 2023-04-26
Also published as: GB202115207D0

Abstract

A rotary shaft coupling 10 comprises a splined male component 12, e.g. an input shaft of a motor vehicle drive axle, insertable into a splined female component 11 of a propellor shaft. The female component 11 comprises a circlip 28 which fits into a groove and retains the female component 11 in the male component 12. The male component 12 comprises clearance regions 23, 24 which, when the coupling is assembled, engage with clearance regions 25, 26 of the female component 11. A chamfer 22 on the female component 11 engages the circlip 28 and O ring seal 30, which reduces their diameter to allow them to pass to their corresponding recesses as the male component 12 enters the female component 11. When the circlip 28 reaches the recess 20 it expands so that the male component 12 and the female component 11 are retained together.

Description

ROTATING SHAFT COUPLING

TECHNICAL FIELD

The present disclosure relates to a rotating shaft coupling. Embodiments of the present disclosure relate to a rotating shaft coupling for a rotating shaft, in particular a propeller shaft of a vehicle.

BACKGROUND

A typical motor vehicle, such as a car, may have an internal combustion engine at a distance from a drive axle. A propeller shaft transmits torque from the engine to the axle, usually via a multi-speed transmission. In the most common arrangement the transmission is in unit with the engine, but the transmission may alternatively be in unit with the drive axle. A propeller shaft is typically 1-2.5m long, and may include one or more support bearings towards the centre thereof. Where a vehicle has several drive axles, a propeller shaft may be provided for each of them.

A propeller shaft should be rotationally balanced if intended to turn at speed, as is the case in a vehicle. Typically in a vehicle, a propeller shaft must be designed for rotation at engine speed without exhibiting significant out of balance forces. Imbalance may be noticeable to the vehicle driver and vehicle occupants, and may induce noise and vibration in the vehicle structure and driveline in addition to reducing the life of bearings associated therewith. Although a propeller shaft may have satisfactory rotational balance, it is also necessary to ensure that the end couplings thereof allow co-axial connection with the input and output drive members. Run-out, as a result of non-axial connection can result in generation of significant out of balance forces.

One kind of conventional connection provides the propeller shaft with a flange mounting for connection to a corresponding flange of an input member (e.g. transmission output shaft) and/or an output member (e.g. input shaft of a drive axle). Simple flange connections provide for fixing axially and radially, but do not eliminate the possibility of run-out at the coupling, and hence imbalance.

An alternative is to use a male/female spline connection to transmit torque. This arrangement is generally of lesser radial size, and thus less susceptible of generating out of balance forces; however a means of fixing against relative axial movement generally required. Additionally a small degree of radial clearance is necessary to facilitate assembly of the splined connection, so that the possibility of run-out at the coupling is not wholly eliminated.

In GB2524758, a rotary shaft coupling was proposed which comprised a male component insertable into a female component on an axis of rotation, the male and female components having a corresponding non-circular (splined) form to transmit torque. The male component had a clamp nut rotatable thereon about the axis of rotation, distal of the splined form and having an internal thread for engagement with an external thread of the female component.

The clamp nut was retained on the male component by a clip. The male and female components each included respective circular regions adapted for engagement without radial clearance. A circular region of the male component was adjacent the non-circular form thereof, and was engageable with the circular region of the female component by on-screwing of said clamp nut.

This configuration works well, but in some cases packaging constraints of the vehicle architecture may prohibit, or at least make it challenging, to accommodate a rotating shaft coupling having a nut, which increases the radial size of the coupling.

It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a rotating shaft coupling, a method of coupling together two transmission shafts, and a vehicle, as claimed in the appended claims.

According to an aspect of the invention, there is provided a rotary shaft coupling comprising a male component insertable into a female component on an axis of rotation, the male and female components having corresponding non-circular mating surfaces so as to be adapted to transmit torque therebetween, the female component being retained on said male component by a radial component of said coupling, wherein said male and female components include respective clearance regions adapted for clearance fit engagement when adjacent, a clearance region of said male component being axially adjacent the non-circular mating surface thereof, and being engageable with the clearance region of the female component by urging the male component and female component together.

In this way, by replacing an interference fit connection with a clearance fit connection, no nut is required In particular, clearance regions can be provided on a male and female interface without the use and presence of a nut to assemble / disassemble the coupling. This results in a reduction in assembly time as no assembly tool is required. Installation can therefore be very straightforward, via push fit. Removal may be via a single service tool, such as a slide hammer. This is simpler than for a clearance fit arrangement utilising a nut, which requires the nut to be screwed on and off, and the use of two service tools to achieve disassembly. In addition, the effect of a nut on rotational balancing of the rotary shaft coupling is removed, resulting in improved NVH (noise, vibration and harshness) attributes.

The radial component may comprise a circlip, and said female component and male component may have respective recesses for engagement with said circlip.

The recess of the male component may be a groove. Similarly, the recess of the female component may be a groove.

The circlip may be radially expandable over the non-circular mating surface of the male component. The circlip may be radially compressible into the recess of the female component.

The non-circular mating surfaces may comprise splines.

A circular clearance region may be provided at each end of the non-circular mating surface of said male component, and a corresponding clearance region may be provided at each end of the non-circular mating surface of said female component.

The coupling may comprise a sealing ring, disposed in a groove on the male component, the sealing ring being compressed by a chamfered leading edge of the female component when the male component is inserted into the female component, the sealing ring remaining in a compressed state when the male component is fully inserted into the female component.

The rotary shaft coupling can therefore be understood to have male and female clearance regions with radial clearance, to be retained by a clip (preventing the male and female parts from coming apart during use) and sealed by use of an o-ring, which centralises the male and female parts with respect to each other, keeps the clearance fit regions apart (and thus in a clearance fit), and provides a sealing function to prevent or at least inhibit ingress of debris and the escape of lubricants.

The circular clearance fit regions may be provided at each end of the non-circular mating surface of the male component. The circular clearance region at the proximal end of said splines may have a diameter which is substantially the root diameter of said splines. The circular clearance region at the distal end of said splines has a diameter which is substantially the outside diameter of said splines.

According to another aspect, there is provided a transmission assembly of a vehicle, having a propeller shaft comprising a female component according to the above, and an input shaft of a drive axle comprising a male component according to the above.

The input shaft may comprise the shank of a drive axle input pinion.

According to another aspect, there is provided a motor vehicle having a drive-line including the transmission assembly according to the above.

According to another aspect, there is provided a method of assembling the rotary shaft coupling described above, the method comprising: inserting the male component in the female component until said non-circular mating surfaces are adjacent.

According to another aspect, there is provided a method of disassembling the rotary shaft coupling by: withdrawing the male component from the female component.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 schematically shows a vehicle to which the present invention is applied; Figure 2 schematically shows a male part of a rotary shaft coupling; Figure 3 schematically shows a female part of the rotary shaft coupling; Figure 4 schematically shows the male and female parts of the rotary shaft coupling in engagement with each other; and Figure 5 schematically shows a clearance region formed in a non-circular surface of a female part of the rotary shaft.

DETAILED DESCRIPTION

A vehicle 1 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 1.

With reference to Figure 1, the vehicle 1 comprises an engine 2, and a driveline 4 for delivering power from the engine, via a transmission 3, to wheels 5 of the vehicle 1. The driveline 4 comprises a propshaft, which connects to an output shaft of the transmission 3 via a rotary shaft coupling.

Figures 2 to 4 describe an example implementation of a rotary shaft coupling (joint assembly) which utilises a clearance fit connection (without a nut), instead of an interference connection requiring a nut to achieve the interference fit.

With reference to Figures 2 to 4, a rotary joint assembly 10 consists of a female component 11 and a male component 12, having a rotational axis 13. The female component 11 includes internal splines 14 for sliding engagement with external splines 15 of the male component 12, thereby to transmit torque about the axis 13. The splines 14, 15 define non-circular mating surfaces.

The mouth of the female component 11 has a chamfer 22 to ease insertion of the male component 12 in use. A circular recess 20 is provided to accommodate a locking ring or circlip, to be described below.

The male component 12 includes a nose 23 comprising a plain diameter less than the external diameter of the external splines 15, and a second plain diameter 24 at the inner (distal) end of the splines 15 which is equal to or greater than the external diameter thereof. On the female component 11 corresponding internal diameters 25, 26 are provided at the axial ends of the internal splines 14. These co-operating portions 23, 25 and 24, 26 are a clearance fit in use, as will be explained. The clearance provided between the co-operating surfaces may be between 0 and 60 pm, for example.

Distal of the plain diameter 24, two circular grooves are provided on the external diameter of the male component 12. Closest to the external splines 15, a first groove 27 is sized and shaped to receive a circlip 28 of a known kind somewhat similar to a piston ring. The first groove 27 is in the Figures obscured by the presence of the circlip 28. The circlip 28 is a snap-fit in the first groove 27 and is sized to enter the circular recess 20 of the female component 11. The second groove 29 retains a resilient 0 ring 30 of conventional kind. The second groove 29 is in the Figures obscured by the presence of the 0 ring 30.

Also illustrated in Figures 2 to 4 are conventional undercuts 32, 33 to avoid a radiused edge at the adjacent radial face.

One method of connection of the joint assembly 10 is to push the male component 12 into the female component 11 to engage the splines 14, 15.

The chamfer 22 of the female component 11 engages the circlip 28, and reduces the diameter thereof to allow it to pass to the recess 20 as the male component 12 enters further into the female component 11. When the circlip 28 reaches the recess 20 it expands so that the male component 12 and the female component 11 are retained together. The 0 ring 30 enters the corresponding bore of the female component 11 to provide a seal against ingress of moisture and other contaminants, and to retain lubricant within the coupling.

Insertion of the male component 12 continues until the portions 23, 25 and 24.26 are adjacent, preserving a clearance fit between these respective parts of the male and female components.

Upon full insertion, the plain diameter portions 23, 24 are disposed in a clearance fit with the corresponding internal diameters 25, 26. This condition is illustrated in Fig. 4. For a clearance fit, the internal diameter of the portions 25, 26 of the female component 11 is the same as, or larger than, the external diameter of the portions 23, 24 of the male component 12. This may mean that there is little or no contact between the portions 23, 24 and 25, 26, particularly when the male and female parts are accurately aligned and stationary. However, in use, small motions of the male and female parts 11, 12 with respect to each other will cause contact between the clearance portion 23 of the male part 12 and the clearance portion 25 of the female part 11, and between the clearance portion 24 of the male part 12 and the clearance portion 26 of the female part 11. More generally, the term clearance fit is used in the art to define a coupling between two parts On this case a hole and shaft) in which the dimensions of the hole and shaft are such that a gap exists between the internal diameter of the hole and the external diameter of the shaft, in other words that the hole size is the same or greater than the shaft size. While the clearance fit at 23, 25 and 24, 26 is unable to ensure perfect axial alignment between the male component and the female component, for certain applications it has been found that this is an acceptable compromise for the reduction in the axial thickness of the coupling. In particular, for certain vehicle architectures, a shaft imbalance calculation allows for clearance to two circular regions on male and female interfaces. Torque is transmissible from the male to female component, or vice versa, via the splines 14, 15.

It will be understood that the internal diameters 25, 26 may be continuous or discontinuous, depending on the manufacturing methods adapted for producing the splines 14. As shown, the internal diameter 26 is substantially continuous, being at or near the base diameter of the splines 14, while the internal diameter 25 may be visually indistinguishable from the splined portion, but in practice clearance is achieved by reducing the height of (and thus the internal diameter of) the splines in this region. The internal diameter 25 is therefore discontinuous as shown.

Figure 5 shows a close up view of part of the portion 25, and in particular shows a side view of a spline 14' of the non-circular surface 14, and a clearance region 25' adjacent to the non-circular surface 14', in which the spline continues, but at a reduced height. In particular, the spine 14 has a height dl, whereas within the clearance region 25' the spline has been machined to a reduced height d2, to provide clearance between the innermost surface of the spline in the clearance portion 25 and the outer surface of the clearance portion 23. As a result, upon full insertion of the male part 12 into the female part 11, the clearance portion 23 will move past the full height splines at 14, to move into the clearance fit engagement with the reduced height splines at 25.

The embodiment illustrated in Figures 2 to 4 is suitable for use in a drive coupling of a propeller shaft of a vehicle, in particular for the connection between a propeller shaft and a drive axle. Although the male and female components may be arranged either way round, in some implementations a propeller shaft is attached to or forms part of the female component 11, and a final drive pinion gear having a stub shaft is attached to or forms part of the male component 12.

To disassemble the coupling between the male component and the female component, it is simply necessary to apply a force to draw the two components apart and away from each other, for example by means of a slide hammer. By this means the female component 11 may be smoothly ejected from the male component 12 until the interference fit between portions 23, 25 and 24, 26 is released, thus permitting the propeller shaft to be released from the drive axle.

For re-assembly, the male and female components 11, 12 are engaged by pushing the male component 11 into the female component 12 at their common axis.

The male/female spline connection is convenient for transmitting torque, but other arrangements are possible, including for example a parallel key or woodruff key.

The male and female components are produced by machining between centres, so that concentricity of the circular portions 23, 25, 24, 26 can be assured.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. For example, all of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.

Claims

CLAIMS1. A rotary shaft coupling comprising a male component insertable into a female component on an axis of rotation, the male and female components having corresponding non-circular mating surfaces so as to be adapted to transmit torque therebetween, the female component being retained on said male component by a radial component of said coupling, wherein said male and female components include respective clearance regions adapted for clearance fit engagement when adjacent, a clearance region of said male component being axially adjacent the non-circular mating surface thereof, and being engageable with the clearance region of the female component by urging the male component and female component together.
2. A coupling according to claim 1, wherein said radial component comprises a circlip, and said female component and male component have respective recesses for engagement with said circlip.
3. A coupling according to any preceding claim wherein said non-circular mating surface comprises splines.
4. A coupling according to any preceding claim and having a circular clearance region at each end of the non-circular mating surface of said male component, and a corresponding clearance region at each end of the non-circular mating surface of said female component.
5. A coupling according to any preceding claim comprising a sealing ring, disposed in a groove on the male component, the sealing ring being compressed by a chamfered leading edge of the female component when the male component is inserted therein, the sealing ring remaining in a compressed state when the male component is fully inserted into the female component.
6. A coupling according to any preceding claim and having a circular clearance fit region at each end of the non-circular mating surface of said male component.
7. A coupling according to claim 6 wherein said circular clearance region at the proximal end of said splines has a diameter which is substantially the root diameter of said splines.
8. A coupling according to claim 6 wherein said circular clearance region at the distal end of said splines has a diameter which is substantially the outside diameter of said splines.
9. A transmission assembly of a vehicle, and having a propeller shaft comprising a female component of any of claims 1-8 and an input shaft of a drive axle comprising a male component of any of claims 1-8.
10. The transmission assembly of claim 9 wherein said input shaft comprises the shank of a drive axle input pinion.
11. A motor vehicle having a drive-line including the transmission assembly of claim 9 or claim 10.
12. A method of assembling the rotary shaft coupling of claim 1 and comprising: inserting the male component in the female component until said non-circular mating surfaces are adjacent.
13. The method of claim 10 and further comprising disassembling the rotary shaft coupling by: withdrawing the male component from the female component.