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
  • F16H3/00—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion
  • F16H3/44—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion using gears having orbital motion
  • F16H3/74—Complexes, not using actuable speedchanging or regulating members, e.g. with gear ratio determined by free play of frictional or other forces
• • 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
  • F16H48/08—Differential gearings with gears having orbital motion comprising bevel 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
  • F16H48/11—Differential gearings with gears having orbital motion with orbital spur gears having intermeshing planet 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
  • F16H48/08—Differential gearings with gears having orbital motion comprising bevel gears
  • F16H2048/082—Differential gearings with gears having orbital motion comprising bevel gears characterised by the arrangement of output shafts
• • 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
  • F16H48/08—Differential gearings with gears having orbital motion comprising bevel gears
  • F16H2048/087—Differential gearings with gears having orbital motion comprising bevel gears characterised by the pinion gears, e.g. their type or arrangement
• • 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
  • F16H48/38—Constructional details
  • F16H48/40—Constructional details characterised by features of the rotating cases

Definitions

• THIS INVENTION relates to a differential gear assembly which finds particular application in the drive train of a motor vehicle but is also usable in any situation where it is desired to create a torque imbalance.
• Figure I is a diagrammatic cross-sectional view of a conventional
• Figure 2 is a diagrammatic, partly sectioned view of a simple >r differential gear assembly embodying the present invention
• FIG. 3 is a diagrammatic, partly sectioned view of one load-sensitive transmission device embodying the invention.
• FIG. 2Q Figure is a diagrammatic, partly sectioned view of another load-sensitive transmission device embodying the invention.
• a conventional vehicle differential assembly comprises a carrier or cage 3 fixed to, or part of, a crown-wheel (not shown) driven by a pinion (not shown) attached to a prop-shaft (not shown).
• Shafts I and 2 are half-shafts each serving a respective road-wheel 0 of the vehicle.
• Idler gears 4 and 5 having the same number of teeth are mounted on stub axles 6 and 7 carried by the carrier 3 and are free to rotate about their own axes.
• the idler gears 4 and 5 mesh with bevel gears 8 and 9 carried respectively by shafts I and 2. 5
• the idler gears 4 and 5 have a similar number of teeth to bevel gears 8 and 9, but this is not essential and in most examples of this type of device bevel gears 8 and 9 would have a greater number of teeth than idler gears 4 and 5. 10
• bevel gear 8 is held fixed, and the carrier 3 is rotated once, then bevel gear 9 will rotate twice in the same direction as that of the carrier.
• a torque of 2T applied to gear 8 will provide an output of 2T at gear 9 with 4T present at the fulcrum.
• Figure 2 shows a split differential gear assembly embodying the present invention employing idler gears in the form of compound gear assemblies.
• first idler gears 14 and 15 are fixed to, or part of, respective lay-shafts 16 and 17 which also carry respective second idler gears 20 and 21.
• the lay-shafts 16 and 17 are mounted, freely running on the carrier 13 radially of the axis of rotation of shafts I 1 and 12 which carry respective bevei gears 18 and 19 engaged respectively with the first idler gears 1 and 15 and the second idler gears 20 and 2 1 .
• idler gears 14 and 1 5 have the same number of teeth as bevel gear 18 and idler gears 20 and 21 have the same number of teeth as bevel gear 1 .
• the rotational gear ratios maintain the i : I characteristics of the device shown In Figure I , the off -set fulcrum allows for a torque split of unequal proportions between the shafts 1 1 and 12.
• the fulcrum F is not situated half-way between the bevel gears 18 and 19 but is closer to gear 19 than to gear 18.
• the proportions of this difference are indicated and, in this example, the distance LI from the fulcrum F to the hypothetical pitch- circle of gears 18, 14 and 15 is three times the distance between the fulcrum and the hypothetical pitch-circle of gears 19, 20 and 21.
• Ratio changes can be included in these devices, but this is not fundamental to the principle of operation. However, such ratio changes would have an effect upon the rotational and torque characteristics.
• a differential gear assembly as illustrated in Figure 2 is capable of allowing a I : I drive coupling through the gears with the carrier 13 held fast, and still allowing for a torque split when drive is applied via the carrier, is a very useful device, and Figures 3 and 4, both illustrating fully variable, constant mesh gear boxes, give some idea of one possible application for such a torque split differential gear assembly.
• Figure 3 shows a load-sensitive transmission device having an input shaft 44 and an output shaft 51 the rotational axis of each shaft coinciding with the main centre datum of the device.
• Input-shaft 44 is fixed to, or part of, a differential hub or carrier 35, this being provided with two radial stub-axles 34 and 37, the axes of the two stub-axles being at 90° to the axis of input shaft 44.
• Outer case 66 is intended to provide an earth, or stationary reference. Any torque introduced by way of input shaft 44 will, therefore, be subjected to torque splitting. Thus, if one unit of torque I I is applied to input shaft 44, then the idler gears 38 and 32 provide two outputs, each of
• Bevelled gear 39 is fixed to, or part of, sleeve-shaft 40 and bevelled gear 31 is fixed to, or part of, shaft 30.
• Shafts 40 and 30 have the same rotational axis datum as shafts 44 and 51 , and shaft 40 is concentric with shaft 44 but bearing located in such a way as to allow totally indpendent rotational capability.
• Shaft 30 is provided with a spur-gear 29, located at the opposite end ot the bevelled gear 31.
• Gear 29 is engaged with gear 25 at a suggested ratio of 2 : I i.e. if gear 29 has 20 teeth, then gear 25 will have 40 teeth.
• Sleeve shaft 40 is also provided with a spur-gear 43 and this is engaged at a suggested ratio of I : I with spur -gear 42.
• Path 31 30, 29, 25, and path
• Spur-gear 25 is fixed to, or part of lay-sdt ⁇ ft 24 and spur-gear 42 is fixed to, or part of, lay-shaft 41 .
• Lay-shaft 24 is provided with compound spur-gear 23
• lay-shaft 41 is provided with compound spur-gear 27. Both assemblies 25, 24, 23 and 42, 41 , 27 are case-held, free-running items.
• Spur-gear 23 is engaged with sun-gear 22 at a suggested ratio of 4 : I and spur-gear 27 is engaged with spur-gear 28 at a suggested ratio of I : I .
• gears 28 and 22 will rotate in the same direction as the input shaft 44.
• Gear 28 is fixed to, or part of, lay-shaft 26, and compound spur-gear 19 is also fixed to, or part of, lay-shaft 26.
• Gear 19 is engaged with sun- gear 21 at a ratio of 2 : I , so that gear 21 will rotate in a direction opposite to that of the input shaft 44 at a torque value similar to that of the input shaft: i.e. if I T is introduced via shaft 44, then IT will be present at gear 21.
• gear 23 As gear 23 is engaged at a ratio of 4 ; 1 with sun-gear 22 and gear 22 is fixed to, or part of, shaft 43, it will mean that the assembly 22, 63 will rotate in the same direction as the input-shaft 44 and with a torque value four times as great: i.e., if IT is introduced by shaft 44 then shaft 63 will rotate ai 4T.
• Gear 71 is fixed to, or part of, sieeve-shaft 70 which is concentric with shaft 63 but bearing separated. Therefore, sleeve-shaft 70 rotates in an opposite direction to that of shaft 63 without any direct reference to shaft 63.
• Shaft 70 is also fixed to, or part of, bevelled gear 68 and shaft 63 is fixed to, or part of, differential carrier 58, the whole of the resultant output section being similar to the differential assembly described with reference to Figure 2.
• the output differential is a torque splitting or dividing assembly and the rotational inputs from the two torque paths from input shaft 44 enable a balanced drive to be established.
• the out-of-balance torque split incorporated in this particular example is one using a lever system across the fulcrum F in which one side of the lever is three times longer than the other. Therefore, if the fulcrum (as represented by stub-axles 60 and 56) is driven forward (i.e. in the same direction as input shaft 44), the torque present upon the fulcrum will be divided unequally: i.e. if IT were introduced via the fulcrum, then, as in Figure 2, the torque split will provide the shorter arm with three quarters of the available torque, and the longer arm with only one quarter of the available torque.
• the two conical assemblies can be of any suitable configuration which provides for an off-set rotational centre: i.e. a centre of rotation that does not coincide with the centre datum situated between the two engaged pitch circles: i.e. gears 67 and 53 are engaged with output gear 52 and compound idler gears 57 and 55 are engaged with the first bevelled gear 68.
• gear 68 will be at I : I with the input shaft 44.
• gear 52 is forward loaded with 3T.
• gear 68 should rotate, with the fulcrum locked, then the output gear 52 will rotate at I : I with the input shaft 44, with gear 31 stationary and gear 39 rotating twice for every single revolution of shaft 44. If gear 68 is stationary, together with gear 39, then the fulcrum will move forwards by 0.25 of a revolution.
• the torque loading of gear 52 remains constant at 3T.
• the output gear 52 is fixed to, or part of, output shaft 5 1 and, assuming this is the loaded termination, the establishment of 3T at gear 2 suggests that a 3T load connected to shaft I can be driven. Theref ore, if gears 39 and 31 rotate in unison with shaft 44 (i.e. one revolution of shaft 44 producing one revolution of both gears in the same direction), then gear 68 will rotate 0.50 revolutions in the opposite direction to sahft 44, and carrier 58 will rotate only 0.125 revolutions in the same rotational direction as shaft 44.
• gear 39 If. for example, gear 39 is stationary, and input shaft 44 is rotated by one revolution, then gear 22 will rotate only 0.25 revolutions (providing 29/25 is 2 : I is 4 : I ) and gear 68 will be stationary. This results in carrier 58 rotating forward 0.25 revolutions, thereby causing gear 52 to rotate forward by 0.50 revolutions.
• gear 3 1 is stationary
• shaft 44 is rotated forward by one revolution
• gear 39 is rotated forward by 2 revolutions.
• the speed differentiation between input 44 and output 51 gives an operating range of 2 : I to I : I with a 3T output capability available at ail times-.
• The: spreed change is governed by the speed of the output shaft (the load)a ⁇ d assuming that the load can be accelerated, then the differentiation across the input differential will take place, enabling equalisation to take place.
• the input/output capability can be extended, by making the basic reduction path 31 , 19, 25, 23, 22 more capable. For example, assuming gear 29 is still provided with 0.50T, then by making the 29, 25 engaged 4 : I instead of the present 2 : 1 , the overall ratio between gear 31 and hub 58 would be 8 : I . However, this would require the off-set fulcrum " to be corrected, i.e. repositioned so as to aliow L I to be seven times longer than L2 if a top-speed ratio of I : I is to be maintained. This would also increase the torque capability to a 7 : I output.
• the speed difference would, however, give the following bottom speed capability a lower differential factor: i.e. if gear 39 were stationary, and shaft 44 were to rotate forward one revolution at IT, then the 8 : I reduction between gears 29 and 21 wouid cause the carrier 58 to rotate forward by 0. 125 revolutions.
• This muitipled by the 2 : 1 differential factor i.e.. rotational ratio across the output differential
• the input differential described is a I : I device. However, this could be a split differential, or a ratio stepped differential, if required, and 0 imbalances can be included and almost any speed ratios can be contemplated.
• Figure 4 illustrates a device similar to that of Figure 3, but in which input differential is not driven by the carrier.
• the input 5 differential is driven by a input applied to the first bevelled gear 136.
• Stub axles 131 and 1 32 are fixed to, or part of, differential carrier 135 which is, itself, fixed to or part of datum shaft 127 which is also 5 provided with a spur-gear 122 and a bearing location shaft 137.
• Idlers 130 and 129 are also engaged with bevelled gear 1 28 which is fixed to, or part of, concentric sleeve shaft 126.
• Sleeve shaft 126 is bearing loc ⁇ ted around shaft 127 sharing the same axial datum, and is provided with a spur-gear 123.
• Lay-shaft 1 17 is a free-running item provided with compound planet gears 124 and 1 16, these being engaged with sun-gears 123 and 1 15 respectively.
• the through-ratio from gear 1 23 to gear 1 15 is I : I .
• gear 1 15 is fixed to or part of sleeve shaft 1 14, which is itself fixed to, or part of gear 1 13, gear 1 13 is also driven at a ratio of I : I relative to gear 28 and in the same directions i.e. opposite to that of input shaft 138.
• the direction of gear 128 is rotationaliy reversed by idler gears 130 and 129-.
• Sleeve lay -shaft 120 is concentric with lay-shaft 1 17 and is provided with two compound planet gears 121 and 1 19, these being engaged with sun- gears 122 and 1 18 respectively.
• the through-ratio from carrier 135 to gear I 18 is 5 : 1 , so that shaft I 12 which is fixed to, or part of, gear I 18 is driven at 5 : I down 5 revolutions of shaft 138 resulting in one revolution of shaft 1 12 in the same rotational direction.
• Output differential carrier I 10 is fixed to, or part of, shaft 1 12 and is therefore driven forward at a rate of 5 : I .
• a torque of IT applied to shaft 138 will thus result in 5T being applied to carrier I 10.
• the output differential shown in Figure 4 is similar to that shown in Figure 3. However, the split, or off-set fulcrum F provides at 4 : 1 imbalance.
• Gear 1 13 is engaged with 109 and I I I .
• Compound bevelled idlers 103 and 105 are engaged with output bevelled gear 102 and all enagements are indicated as being 1 : 1.
• L I is four times longer than L2, means that the 5T present at the indicated fulcrum (i.e. the axial datum of axles 107 and 106) will be split into IT and 4T proportions IT out from gears 109 and I I 1 to gear I 1 3 and 4T out from gears 103 and 1 05 to gear 102.
• Torque split differential assemblies embodying the present invention can be incorporated into transmission trains in many different ways, and Ffgures 3 and 4 are included merely as examples. Furthermore, the I : I ratios Indicated in Figures 2, 3 and 4 can be modified to include other variations, maintaining the basic off-set fulcrum principle, however.
• off-set torque split differential assemblies shown in this specification are based upon bevelled differential arrangements. However, it is envisaged that the principle could equally be applied to other forms of gear, such as epicylic and compound spur-gears, for example.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Retarders (AREA)
• Arrangement And Driving Of Transmission Devices (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 1985
  • 1985-11-07 GB GB8527527A patent/GB8527527D0/en active Pending
• 1986
  • 1986-11-07 GB GB8626638A patent/GB2182988A/en not_active Withdrawn
  • 1986-11-07 EP EP19860906416 patent/EP0246268A1/de not_active Withdrawn
  • 1986-11-07 AU AU65912/86A patent/AU6591286A/en not_active Abandoned
  • 1986-11-07 WO PCT/GB1986/000691 patent/WO1987003061A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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