WO1999034134A1 - Shaft support for an infinitely-variable-ratio transmission - Google Patents

Shaft support for an infinitely-variable-ratio transmission Download PDF

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Publication number
WO1999034134A1
WO1999034134A1 PCT/GB1998/003754 GB9803754W WO9934134A1 WO 1999034134 A1 WO1999034134 A1 WO 1999034134A1 GB 9803754 W GB9803754 W GB 9803754W WO 9934134 A1 WO9934134 A1 WO 9934134A1
Authority
WO
WIPO (PCT)
Prior art keywords
discs
input
shaft
rollers
output
Prior art date
Application number
PCT/GB1998/003754
Other languages
French (fr)
Inventor
Leslie Kendrick Robinson
Original Assignee
Torotrak (Development) Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Torotrak (Development) Limited filed Critical Torotrak (Development) Limited
Priority to EP98960015A priority Critical patent/EP1042624A1/en
Priority to KR1020007007070A priority patent/KR20010033560A/en
Priority to JP2000526755A priority patent/JP2002500326A/en
Publication of WO1999034134A1 publication Critical patent/WO1999034134A1/en

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H15/00—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members
    • F16H15/02—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members without members having orbital motion
    • F16H15/04—Gearings providing a continuous range of gear ratios
    • F16H15/06—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B
    • F16H15/32—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B in which the member B has a curved friction surface formed as a surface of a body of revolution generated by a curve which is neither a circular arc centered on its axis of revolution nor a straight line
    • F16H15/36—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B in which the member B has a curved friction surface formed as a surface of a body of revolution generated by a curve which is neither a circular arc centered on its axis of revolution nor a straight line with concave friction surface, e.g. a hollow toroid surface
    • F16H15/38—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B in which the member B has a curved friction surface formed as a surface of a body of revolution generated by a curve which is neither a circular arc centered on its axis of revolution nor a straight line with concave friction surface, e.g. a hollow toroid surface with two members B having hollow toroid surfaces opposite to each other, the member or members A being adjustably mounted between the surfaces

Definitions

  • the present invention relates to infinitely-variable-ratio transmission apparatus of the toroidal race rolling friction type, hereinafter referred to as a variator.
  • a main shaft which takes drive from an engine e.g. an internal combustion engine to two input discs which are mounted on the shaft.
  • Two output discs are mounted back to back between the input discs and are free to rotate relative to the shaft.
  • motion is transferred from the input discs to the output discs via a plurality of rollers positioned in toroidal cavities which are provided between the input discs and the output discs.
  • the rollers are subjected to hydraulic forces so that they make contact with the faces of the respective input and output discs in order to transmit power from the input discs to the output discs.
  • the power is transferred from the output discs via a chain or belt drive to a further transmission component such as an epicyclic gear box.
  • the drive through the chain or belt exerts a transverse load onto the shaft and causes the shaft to flex.
  • the degree of flexing is relatively small but has the potential of causing a significant effect on the position of the two output discs which can cause the load on some of the rollers to be increased i.e. a crushing effect will be applied, whilst the load on some of the remaining rollers will be decreased, thereby not allowing the drive to be transferred efficiently from the input to the output discs.
  • the present invention seeks to provide a transmission apparatus in which the output discs are located on bearing means, and the bearing means are supported, so that the shaft is isolated from bending loads applied to the output discs.
  • the present invention provides a variator transmission apparatus comprising a housing, an input shaft, two input discs mounted on an auxiliary shaft for rotation therewith, an output disc assembly, the input discs and the output disc assembly defining between them two toroidal cavities, a plurality of rollers located in the cavities and the apparatus being subjected to an end load to maintain the rollers in contact with the respective discs and disc assembly in order to transmit drive, characterised in that the input shaft is arranged to drive the auxiliary shaft and the output disc assembly is supported from the housing.
  • One of the input discs can be mounted for rotation with the input shaft and be provided with abutment means to limit axial movement, whilst the other one of the input discs is also mounted for rotation on the input shaft and be axially moveable thereon, under an applied load to maintain the rollers into contact with the respective surfaces of the input and output discs.
  • the output disc assembly can be mounted on bearing means which are supported from the housing.
  • the housing can comprise a transmission housing, or a cradle attached to the transmission housing.
  • Figure 1 shows a diagrammatic representation of a steplessly-variable-ratio transmission apparatus of the type to which the present invention can be applied;
  • Figure 2 shows a diagrammatic view of one form of variator according to the present invention.
  • an infinitely-variable-ratio transmission apparatus which comprises an input shaft (10), two input discs (12, 14), two output discs (16, 18), two sets of rollers (20, 22) which are located in toroidal cavities (24, 26) which are formed between the input and output discs, and a chain or belt drive (28) which is mounted on the two output discs (16, 18).
  • the two inputs discs (12, 14) are mounted for rotation with the shaft (10) e.g. by means of splined mountings, whilst the output discs (16, 18) are free to rotate relative to the shaft (10).
  • Both of the input discs (12, 14) have limited axial movement and one of the discs e.g. disc 12 is prevented by an abutment (not shown) on the shaft (12) from moving too far to the left as shown in Figure 1.
  • the other disc (14) is subjected to an end load operating towards the left as shown in Figure 1 e.g. by means of hydraulic pressure or the like so that the sets of rollers (20, 22) are forced into contact with the toroidal surfaces of the input and output discs, thereby allowing drive to be transmitted from a power source e.g. an internal combustion engine via the chain drive (28) to a further component of a vehicle transmission e.g. an epicyclic gearbox (not shown).
  • a power source e.g. an internal combustion engine via the chain drive (28)
  • a further component of a vehicle transmission e.g. an epicyclic gearbox (not shown).
  • the increase in load on some of the rollers may be unacceptable in that unduly high stresses are caused within the rollers, whilst the decrease in load on the remaining rollers is likely to reduce the efficiency of the drive between the input and output discs because slipping may occur between the input and output discs.
  • the present invention proposes a design which restrains the output disc assembly, and isolates the input shaft from bending forces applied to the output disc assembly.
  • a variator (30) comprises an input shaft (32) which receives power from, for example, an internal combustion engine, is arranged to drive by means of a splined coupling (34), an auxiliary input shaft (36).
  • a splined coupling 34
  • auxiliary input shaft 36
  • the auxiliary shaft (36) is mounted in bearings (42, 44) which are located in a cradle (46), the cradle itself being mounted within a transmission housing (48).
  • Two output discs (50, 52) are mounted in bearings (54), the bearings being supported by a web or radial struts or some such load bearing structure (56) in the cradle (46).
  • Sets of rollers (58, 60) are located between the input and output discs (38, 50) and (40, 52) respectively.
  • the surfaces of the input and output discs are shaped so as to create two toroidal cavities (62, 64) in which the sets of rollers (58, 60) are located.
  • the drive from the output discs can then be taken by a chain or belt, for example, to another transmission element of a vehicle drive.
  • the other transmission element can be an epicyclic gearbox.
  • the bearings (42, 44) are bearings of the roller type which do not provide any axial location. This enables the auxiliary shaft (36) to float axially within limits enabling the input discs to move under hydraulic pressure applied to one of the discs so that the rollers (58, 60) make driving contact with the surfaces of the input and output discs.
  • the provision of the cradle (46) isolates the variator (30) from any distortion of the transmission casing (48). In the situation where there is unlikely to be any deflection of the transmission casing the cradle can be dispensed of.
  • the output discs (50, 52) are mounted with respect to the casing as also is the auxiliary shaft (36).
  • the bearings for the auxiliary shaft can be roller bearings.
  • the roller bearings for the auxiliary shaft (36) can be dispensed with and replaced by plain bushes with clearance so that the bushes act as a steady only.

Abstract

The present invention provides an infinitely-variable-ratio transmission (30) in which the two input discs (38, 40) are mounted on an intermediate or auxiliary input shaft (36) which is splined to the main input shaft (32) for rotation therewith. The auxiliary input shaft (36) is mounted in bearings (42, 44) which are located in a cradle (46) which is itself mounted within the transmission housing (48). Flexing of the input shaft (32) is avoided as the load is taken by the cradle (46).

Description

SHAFT SUPPORT FOR AN INFINITELY- VARIABLE-RATIO
TRANSMISSION
The present invention relates to infinitely-variable-ratio transmission apparatus of the toroidal race rolling friction type, hereinafter referred to as a variator.
In such apparatus there is employed a main shaft which takes drive from an engine e.g. an internal combustion engine to two input discs which are mounted on the shaft. Two output discs are mounted back to back between the input discs and are free to rotate relative to the shaft.
In such an arrangement motion is transferred from the input discs to the output discs via a plurality of rollers positioned in toroidal cavities which are provided between the input discs and the output discs.
The rollers are subjected to hydraulic forces so that they make contact with the faces of the respective input and output discs in order to transmit power from the input discs to the output discs. The power is transferred from the output discs via a chain or belt drive to a further transmission component such as an epicyclic gear box.
The drive through the chain or belt exerts a transverse load onto the shaft and causes the shaft to flex. The degree of flexing is relatively small but has the potential of causing a significant effect on the position of the two output discs which can cause the load on some of the rollers to be increased i.e. a crushing effect will be applied, whilst the load on some of the remaining rollers will be decreased, thereby not allowing the drive to be transferred efficiently from the input to the output discs.
It will be appreciated that the effect of shaft flexing is in effect a distortion of the toroidal cavities between the input and output discs. A solution to the above problem can be summarised as preventing or minimising flexing of the shaft by earthing or anchoring the output discs.
The present invention seeks to provide a transmission apparatus in which the output discs are located on bearing means, and the bearing means are supported, so that the shaft is isolated from bending loads applied to the output discs.
Accordingly the present invention provides a variator transmission apparatus comprising a housing, an input shaft, two input discs mounted on an auxiliary shaft for rotation therewith, an output disc assembly, the input discs and the output disc assembly defining between them two toroidal cavities, a plurality of rollers located in the cavities and the apparatus being subjected to an end load to maintain the rollers in contact with the respective discs and disc assembly in order to transmit drive, characterised in that the input shaft is arranged to drive the auxiliary shaft and the output disc assembly is supported from the housing.
One of the input discs can be mounted for rotation with the input shaft and be provided with abutment means to limit axial movement, whilst the other one of the input discs is also mounted for rotation on the input shaft and be axially moveable thereon, under an applied load to maintain the rollers into contact with the respective surfaces of the input and output discs.
The output disc assembly can be mounted on bearing means which are supported from the housing.
The housing can comprise a transmission housing, or a cradle attached to the transmission housing.
The present invention will now be more particularly described with reference to the accompanying drawings in which, Figure 1 shows a diagrammatic representation of a steplessly-variable-ratio transmission apparatus of the type to which the present invention can be applied;
Figure 2 shows a diagrammatic view of one form of variator according to the present invention.
Referring to Figure 1, there is shown an infinitely-variable-ratio transmission apparatus (a variator) which comprises an input shaft (10), two input discs (12, 14), two output discs (16, 18), two sets of rollers (20, 22) which are located in toroidal cavities (24, 26) which are formed between the input and output discs, and a chain or belt drive (28) which is mounted on the two output discs (16, 18).
The two inputs discs (12, 14) are mounted for rotation with the shaft (10) e.g. by means of splined mountings, whilst the output discs (16, 18) are free to rotate relative to the shaft (10).
Both of the input discs (12, 14) have limited axial movement and one of the discs e.g. disc 12 is prevented by an abutment (not shown) on the shaft (12) from moving too far to the left as shown in Figure 1.
The other disc (14) is subjected to an end load operating towards the left as shown in Figure 1 e.g. by means of hydraulic pressure or the like so that the sets of rollers (20, 22) are forced into contact with the toroidal surfaces of the input and output discs, thereby allowing drive to be transmitted from a power source e.g. an internal combustion engine via the chain drive (28) to a further component of a vehicle transmission e.g. an epicyclic gearbox (not shown).
It will be appreciated that the chain drive (28) exerts a bending load on the shaft (10) and therefore there is a distortion in the shape of the toroidal cavities (24, 26). It will thus be appreciated that the load on some of the rollers (20, 22) will be increased whilst the load on the remaining rollers can be decreased.
The increase in load on some of the rollers may be unacceptable in that unduly high stresses are caused within the rollers, whilst the decrease in load on the remaining rollers is likely to reduce the efficiency of the drive between the input and output discs because slipping may occur between the input and output discs.
In order to prevent or substantially reduce the effect of the distortion of the shapes of the toroidal cavities (24, 26) which can be produced by a bending load being applied to the shaft (10), the present invention proposes a design which restrains the output disc assembly, and isolates the input shaft from bending forces applied to the output disc assembly.
Referring to Figure 2, a variator (30) comprises an input shaft (32) which receives power from, for example, an internal combustion engine, is arranged to drive by means of a splined coupling (34), an auxiliary input shaft (36). Mounted on the shaft (36) are two input discs (38, 40). Both discs (38, 40) are mounted so as to be rotatable with the auxiliary shaft (36) but the disc (40) is axially moveable with respect to the shaft (36) under an applied force, e.g. the application of the end load.
The auxiliary shaft (36) is mounted in bearings (42, 44) which are located in a cradle (46), the cradle itself being mounted within a transmission housing (48).
Two output discs (50, 52) are mounted in bearings (54), the bearings being supported by a web or radial struts or some such load bearing structure (56) in the cradle (46).
Sets of rollers (58, 60) are located between the input and output discs (38, 50) and (40, 52) respectively. The surfaces of the input and output discs are shaped so as to create two toroidal cavities (62, 64) in which the sets of rollers (58, 60) are located.
In operation an hydraulic load is applied to the input disc (40) which forces the sets of rollers into contact with the respective faces of the input and output discs and rotation of the input shaft (32) causes power to be transferred from the input discs (38. 40) to the output discs (50, 52).
The drive from the output discs can then be taken by a chain or belt, for example, to another transmission element of a vehicle drive. The other transmission element can be an epicyclic gearbox.
It will be appreciated that the load exerted by the drive from the output discs (50, 52) on the support structure (56) will not cause any flexing of the input shaft (32) nor the auxiliary shaft (36). Instead the load will be taken by the cradle (46).
As both the input shaft (32) and the auxiliary shaft (36) are isolated from the load exerted by the drive from the output discs (50, 52) the toroidal cavities (62, 64) will not be distorted and the load on the rollers (58, 60) will not be affected by the load exerted by the drive from the output discs.
In the above arrangement the bearings (42, 44) are bearings of the roller type which do not provide any axial location. This enables the auxiliary shaft (36) to float axially within limits enabling the input discs to move under hydraulic pressure applied to one of the discs so that the rollers (58, 60) make driving contact with the surfaces of the input and output discs.
Also in the above arrangement it will be appreciated that the provision of the cradle (46) isolates the variator (30) from any distortion of the transmission casing (48). In the situation where there is unlikely to be any deflection of the transmission casing the cradle can be dispensed of. In such an arrangement the output discs (50, 52) are mounted with respect to the casing as also is the auxiliary shaft (36).
In such an arrangement the bearings for the auxiliary shaft can be roller bearings. In a further arrangement (not shown) the roller bearings for the auxiliary shaft (36) can be dispensed with and replaced by plain bushes with clearance so that the bushes act as a steady only.
It will be appreciated that in the embodiments of the invention described above i.e. with or without a cradle, with either roller bearings or plain bushes for the auxiliary shaft, the load applied to the variator (30) to the drive from the output discs (50, 52) does not apply a bending load to the input shaft (32) nor the auxiliary shaft (36). Therefore in all cases the shape of the toroidal cavities (62, 64) is not affected and the rollers (58, 60) remain in driving contact with the respective input and output discs in order to transmit drive without slippage.

Claims

1. A variator transmission apparatus comprising a housing, an input shaft, two input discs mounted on an auxiliary shaft for rotation therewith, an output disc assembly, the input discs and the output disc assembly defining between them two toroidal cavities, a plurality of rollers located in the cavities and the apparatus being subjected to an end load to maintain the rollers in contact with the respective discs and disc assembly in order to transmit drive, characterised in that the input shaft is arranged to drive the auxiliary shaft and the output disc assembly is supported from the housing.
2. An apparatus as claimed in Claim 1 in which one of the input discs is mounted for rotation with the input shaft and includes abutment means to limit axial movement, whilst the other one of the input discs is also mounted for rotation on the input shaft and be axially moveable thereon under an applied load to maintain the rollers into contact with the respective surfaces of the input and output discs.
3. An apparatus as claimed in any one of Claims 1 to 4 in which the output disc assembly is mounted on bearing means which are supported from the housing.
4. An apparatus as claimed in any one of Claims 1 to 4 in which the housing comprises a transmission housing, or a cradle attached to the transmission housing.
PCT/GB1998/003754 1997-12-24 1998-12-15 Shaft support for an infinitely-variable-ratio transmission WO1999034134A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP98960015A EP1042624A1 (en) 1997-12-24 1998-12-15 Shaft support for an infinitely-variable-ratio transmission
KR1020007007070A KR20010033560A (en) 1997-12-24 1998-12-15 Shaft support for an infinitely-variable-ratio transmission
JP2000526755A JP2002500326A (en) 1997-12-24 1998-12-15 Shaft support for continuously variable transmission

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9727319.7A GB9727319D0 (en) 1997-12-24 1997-12-24 Improvements in or relating to steplessly-variable-ratio transmission apparatus
GB9727319.7 1997-12-24

Publications (1)

Publication Number Publication Date
WO1999034134A1 true WO1999034134A1 (en) 1999-07-08

Family

ID=10824213

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1998/003754 WO1999034134A1 (en) 1997-12-24 1998-12-15 Shaft support for an infinitely-variable-ratio transmission

Country Status (5)

Country Link
EP (1) EP1042624A1 (en)
JP (1) JP2002500326A (en)
KR (1) KR20010033560A (en)
GB (1) GB9727319D0 (en)
WO (1) WO1999034134A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4701522B2 (en) * 2001-03-21 2011-06-15 株式会社ジェイテクト Toroidal continuously variable transmission
FR3124484B1 (en) 2021-06-23 2023-06-16 Ifp Energies Now Electrically assisted land vehicle with an inverted infinitely variable transmission
FR3128502B1 (en) 2021-10-27 2024-01-19 Ifp Energies Now Variable transmission comprising an epicyclic gear train with conical or frustoconical rollers

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0420157A2 (en) * 1989-09-26 1991-04-03 Nissan Motor Co., Ltd. Toroidal continuously variable transmission
US5368529A (en) * 1992-06-29 1994-11-29 Nsk Ltd. Toroidal type continuously variable transmission

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0420157A2 (en) * 1989-09-26 1991-04-03 Nissan Motor Co., Ltd. Toroidal continuously variable transmission
US5368529A (en) * 1992-06-29 1994-11-29 Nsk Ltd. Toroidal type continuously variable transmission

Also Published As

Publication number Publication date
EP1042624A1 (en) 2000-10-11
GB9727319D0 (en) 1998-02-25
JP2002500326A (en) 2002-01-08
KR20010033560A (en) 2001-04-25

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