Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K17/00—Arrangement or mounting of transmissions in vehicles
  • B60K17/04—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing
  • B60K17/16—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing of differential gearing
• • 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
  • F16H48/00—Differential gearings
  • F16H48/06—Differential gearings with gears having orbital motion
  • F16H48/10—Differential gearings with gears having orbital motion with orbital spur gears
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K1/00—Arrangement or mounting of electrical propulsion units
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K1/00—Arrangement or mounting of electrical propulsion units
  • B60K2001/001—Arrangement or mounting of electrical propulsion units one motor mounted on a propulsion axle for rotating right and left wheels of this axle
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K7/00—Disposition of motor in, or adjacent to, traction wheel
  • B60K7/0007—Disposition of motor in, or adjacent to, traction wheel the motor being electric
• • 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
  • F16H48/00—Differential gearings
  • F16H48/06—Differential gearings with gears having orbital motion
  • F16H48/10—Differential gearings with gears having orbital motion with orbital spur gears
  • F16H2048/104—Differential gearings with gears having orbital motion with orbital spur gears characterised by two ring gears
• • 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
  • F16H48/00—Differential gearings
  • F16H48/06—Differential gearings with gears having orbital motion
  • F16H48/10—Differential gearings with gears having orbital motion with orbital spur gears
  • F16H2048/106—Differential gearings with gears having orbital motion with orbital spur gears characterised by two sun gears
• • 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
  • F16H57/00—General details of gearing
  • F16H57/02—Gearboxes; Mounting gearing therein
  • F16H57/02004—Gearboxes; Mounting gearing therein the gears being positioned relative to one another by rolling members or by specially adapted surfaces on the gears, e.g. by a rolling surface with the diameter of the pitch circle
• • 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
  • F16H63/00—Control outputs from the control unit to change-speed- or reversing-gearings for conveying rotary motion or to other devices than the final output mechanism
  • F16H63/02—Final output mechanisms therefor; Actuating means for the final output mechanisms
  • F16H63/30—Constructional features of the final output mechanisms
  • F16H63/34—Locking or disabling mechanisms
  • F16H63/3416—Parking lock mechanisms or brakes in the transmission
  • F16H63/3425—Parking lock mechanisms or brakes in the transmission characterised by pawls or wheels

Definitions

• the present invention relates to an epicyclic differential transmission particularly suitable for use in vehicles, especially electrically powered vehicles, having two driving wheels.
• Vehicles having two driving wheels and a single source of motive power require a means of dividing a single drive shaft into half shafts associated with respective driving wheels.
• a differential gear is also required to accommodate relative rotation between the driving wheels, for example on cornering.
• a further requirement is that the driving torque is equally split between the driving wheels so as to avoid torque steer, especially in front- wheel-drive vehicles.
• a final drive reduction gear which may be a bevel gear
• a conventional bevel gear differential is incorporated with a conventional bevel gear differential. This arrangement is not particularly compact.
• Electric vehicles typically require only a single speed reduction gear, because the torque characterization of an electric motor allows road speed to be directly proportional to motor speed.
• a co-axial arrangement is desirable in which one half shaft passes axially through the armature of the electric motor to the associated driving wheel.
• a single speed epicyclic differential transmission comprising a housing, an annular rotatable input member having a rotational axis in the housing, opposed rotatable output members on said axis, one of which is adapted to drive through said input member, and an epicyclic gear train arranged about said input member, wherein said input member comprises a sun gear, inner planet gears are provided in mesh with the sun gear, an inner planet gear carrier is provided rotationally fast with the output member associated with said input member, an inner ring gear is provided in mesh on the inside with said inner planet gears, and on the outside with outer planet gears rotatable on axles of said housing, and an outer ring gear is provided in mesh with said outer planet gears and connected to the other of said output members.
• Such an arrangement provides a single speed transmission of short axial length and in which the elements of the epicyclic gear train act as a differential gear to accommodate relative rotation of the respective output member whilst giving a substantially equal torque split between the driving wheels.
• the sun gear, inner planet gears and inner ring gear are arranged in a substantially common plane.
• the inner ring gear, outer planet gears and outer ring gear are arranged in a substantially common plane.
• the sun gear, planet gears and ring gears are all arranged in a substantially common plane.
• the arrangement may further include a locking pawl engageable to retain an element of the epicyclic gear train with respect to the housing, so as to lock the transmission and provide a park-lock function.
• the pawl may for example engage the outer ring gear.
• the sun gear has 33 teeth
• the inner planet gears have 26 teeth
• the inner ring gear has 87 teeth on the inside and 103 teeth on the outside
• the outer planet gears have 19 teeth
• the outer ring gear has 141 teeth.
• the inner ring gear comprises the annulus of an inner epicyclic gear train, and the sun gear of an outer epicyclic gear train.
• This inner ring gear 'floats' between the other elements of the inner and outer epicyclic gear trains in order to give the effect of a differential gear.
• gear ratios a careful choice of gear ratios is required in order to ensure a substantially equal torque split, but this is a matter of calculation which is well within the ability of the skilled transmission engineer whilst bearing in mind the required final drive reduction, and the constraints imposed by dimensions of successive planetary gear elements.
• the axial length of a transmission according to the invention is close to 50% of a conventional final drive/differential unit, and the number of parts is reduced by about 30%. In a small vehicle, short axial length is advantageous because it maximizes space for steering and suspension components.
• the invention also permits incorporation of a locked or limited slip differential, by for example fixing or controlling the speed ratio between the output shafts. This may be done relatively easily since the output members are immediately adjacent and on the same rotational axis.
• Fig. 1 shows a schematic arrangement of a transmission according to the invention
• Fig. 2 shows in axial section a practical embodiment of the scheme of Fig. 1.
• a transmission has a major axis of rotation 10 on which is provided an electric motor 11 having a hollow armature (not shown).
• the armature is directly connected to a hollow input shaft 12 of the transmission, as illustrated, which comprises the sun gear 13 of a two stage epicyclic transmission in which all the major gear components lie in a substantially common plane.
• An array of im er planet gears 14 (typically four) circulate in mesh around the sun gear, and are journalled on the usual planet gear carrier 15.
• This carrier 15 is coupled to one drive shaft 16 which passes through the input shaft 12 and motor 11 for connection to a drive wheel of a vehicle.
• an inner ring gear (annulus) 17 which has gear teeth on the inner diameter in mesh with the inner planet gears 14. Additionally, this inner ring gear has gear teeth on the outside diameter, which thus constitutes a sun gear 18 of an outer epicyclic gear train.
• An array of outer planet gears 19 (typically four) circulate in mesh around the outer sun gear 18, and are journalled on relatively fixed spigots 20 of a transmission casing 21.
• An outer ring gear (annulus) 22 is in mesh with the outer planet gears 19, and is connected to another drive shaft 23 for connection to a second drive wheel of the vehicle.
• drive torque from the electric motor 11 is transmitted via the input shaft 12 to the sun gear 13.
• the reaction torque provided by the inner ring gear 17 causes the inner planet gears to circulate, carrying with them the carrier 15 and drive shaft 16.
• the outer sun gear 18 also rotates (with the inner ring gear 17), and transmits torque to the outer ring gear 22 via the outer planet gears 19.
• These outer planet gears are effectively provided with a stationary carrier constituted by the transmission casing 21.
• the outer ring gear 22 thus rotates, and carries with it the drive shaft 23.
• speed balance between the drive shafts is controlled by road wheels in contact with the road.
• the inner ring gear 17/outer sun gear 18 is the differentiating gear which permits relative rotation of the respective drive shafts (for example during vehicle cornering).
• Drive torque from the electric motor is split between the two epicyclic gear trains, and the torque balance is dictated by the speed ratios which are selected.
• An equal torque split is desirable for vehicle driving wheels on a substantially common axis, but for example other torque splits may be selected for drive shafts connected to different axles of an all wheel drive vehicle, or for special non-automotive applications.
• Fig. 1 illustrates a park lock pawl 24 engageable on demand to lock the outer ring gear 22 to the transmission casing 21. It will be appreciated that by preventing the outer ring gear from rotating, the transmission will be locked against movement, and can thus provide a wheel brake for a vehicle.
• the arrangement is also suitable for modification for external control of the differentiating gear 17/18. It will be appreciated that by externally controlling this gear 17/18, the torque split between the drive shafts 16,23 may be adjusted.
• a suitable means of braking the differentiating gear 17/18 may be a brake band, clutch or viscous coupling.
• the transmission provides for minimum drive shaft articulation during vehicle suspension movement as compared with a conventional arrangement of differential gear between the inner drive shaft ends.
• This arrangement has particular value for small front-wheel-drive vehicles where the vehicle track is relatively narrow.
• the adjacency of the drive shaft ends provides for relatively simple provision of a coupling which lock the drive shafts together or limit relative rotation therebetween. This arrangement can thus provide a locking differential or a limited-slip differential, which is of value in some kinds of vehicle.
• the gears are provided with the following number of teeth, to give a substantially equal torque split with no external control of the differentiating gear 17/18.
• inner sun gear 13 - 33 teeth inner planet gears 14 - 26 teeth inner ring gear 17 - 87 teeth outer sun gear 18 - 103 teeth outer planet gears 19 - 19 teeth outer ring gear 22 - 141 teeth
• FIG. 2 A practical transmission arrangement for a front- wheel-drive vehicle is illustrated in Fig. 2, and shows in more detail the transmission casing 11, bearings, shaft seals and other conventional components. Where appropriate, parts carry reference numerals corresponding to Fig. 1 ; a park-lock arrangement is not illustrated.
• transmission casing 21 is directly bolted to the casing 30 of the electric motor, as illustrated.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Retarders (AREA)
• Arrangement And Driving Of Transmission Devices (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (5)

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• 2004
  • 2004-06-08 GB GBGB0412736.1A patent/GB0412736D0/en not_active Ceased
• 2005
  • 2005-06-08 CN CNA2005800187534A patent/CN1964864A/zh active Pending
  • 2005-06-08 WO PCT/GB2005/002286 patent/WO2005120877A1/en not_active Application Discontinuation
  • 2005-06-08 EP EP05750265A patent/EP1765627A1/de not_active Withdrawn
  • 2005-06-08 JP JP2007526547A patent/JP2008501920A/ja active Pending

Non-Patent Citations (1)

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