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
  • B60K6/00—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines
  • B60K6/08—Prime-movers comprising combustion engines and mechanical or fluid energy storing means
  • B60K6/10—Prime-movers comprising combustion engines and mechanical or fluid energy storing means by means of a chargeable mechanical accumulator, e.g. flywheel
  • B60K6/105—Prime-movers comprising combustion engines and mechanical or fluid energy storing means by means of a chargeable mechanical accumulator, e.g. flywheel the accumulator being a flywheel
• • 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
  • B60K6/00—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines
  • B60K6/20—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
  • B60K6/42—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs characterised by the architecture of the hybrid electric vehicle
  • B60K6/44—Series-parallel type
  • B60K6/445—Differential gearing distribution type
• • 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
  • B60K6/00—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines
  • B60K6/20—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
  • B60K6/50—Architecture of the driveline characterised by arrangement or kind of transmission units
  • B60K6/54—Transmission for changing ratio
  • B60K6/543—Transmission for changing ratio the transmission being a continuously variable transmission
• • 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
  • F16H37/00—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00
  • F16H37/02—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/60—Other road transportation technologies with climate change mitigation effect
  • Y02T10/62—Hybrid vehicles

Definitions

• This invention relates to variators, particularly but not exclusively to variators for transmission systems - for example, vehicle transmission systems.
• Other aspects of the present invention relate to transmission systems, to a propulsion system for a vehicle, and to a vehicle incorporating such a propulsion system.
• Electric hybrid powertrains using electrochemical batteries, power electronics and motor-generators have previously been proposed, but such arrangements tend to be relatively expensive compared to traditional internal combustion engine powertrains. It is also the case that inefficiencies associated with the multiple conversions of energy into different forms that take place in such systems (particularly during regenerative braking) reduces the net amount of energy that can be saved with such a system as compared with a conventional vehicle. It is also the case that electric systems are typically relatively heavy and therefore extra energy is spent transporting this extra mass. Even though fully-electric vehicles will have zero "at the wheel” emissions, it is the case that manufacturing and subsequent end-of-life processing of electrochemical batteries for this application has significant environmental impact.
• flywheel As a kinetic energy storage device to provide a mechanical alternative to electrical systems.
• Previously proposed high-speed flywheel hybrid systems (such as those of Flybrid Automotive Ltd) generally have a higher power-to-weight ratio than equivalent electric hybrid systems and are able to capture and return more of a vehicle's kinetic energy when performing regenerative braking. This is mostly because energy form conversions are avoided, especially during regenerative braking; kinetic energy is simply transferred from one inertia to another (the vehicle and the energy storage flywheel).
• Mechanical transmissions are usually recyclable since they are constructed almost entirely from steel and aluminium (apart from the seals and lubricants and a carbon fibre wrap for the high-speed flywheel). The abundance of these materials means that the cost of the raw material is relatively low, and mass-manufacturing techniques allow relatively low-cost manufacture.
• Automotive Ltd are designed to interface with conventional vehicle architecture, comprising a clutch, discrete gearbox and differential. This is to provide a low-cost system that can be readily accepted by vehicle manufacturers mindful of financial risk, since it does not fundamentally change the layout and overall concept of the vehicle.
• Flybrid Automotive Ltd's current advertised systems are able to accomplish regenerative braking, function in engine stop-start mode (e.g. in a mode where the engine can be turned off while waiting at traffic lights) and drive the vehicle under flywheel power alone.
• the flywheel can be used to allow the engine to operate in a more efficient regime than is normally possible with a discrete gearbox transmission alone.
• One illustrative aim of a particular embodiment of the present invention is to provide a mechanical hybrid powertrain (using a flywheel) that is integral to the main transmission and one that is able to operate in all modes of operation offered by electric hybrid vehicles that aid reduction in energy/fuel consumption.
• a mechanical hybrid powertrain using a flywheel
• an engine or other prime mover
• CVT continuously variable transmission
• Such a function cannot be provided by previously proposed flywheel systems, including those of Flybrid Automotive Ltd. This is because such a function requires a form of mechanical CVT for the engine (or other prime mover) as well as that required for the flywheel.
• One illustrative implementation of the teachings of this invention provides a mechanical CVT for the engine (or other prime mover) as well as a mechanical CVT for controlling energy storage and recovery of a flywheel (or other energy storage device).
• Another illustrative advantage of the mechanical CVTs disclosed herein - as compared with electric CVT systems - is that energy form conversions are avoided; once fuel has been converted into mechanical energy at the engine crank (or energy stored in an electrochemical battery has been converted into mechanical energy at the motor- generator shaft), it remains in this state throughout the transmission. Additionally, the mechanical systems proposed herein will likely be less expensive and more recyclable than their electric alternatives.
• teachings of the invention provide a continuously variable transmission that includes any combination of features disclosed in this application alone, or in combination with any features disclosed in any of the aforementioned priority applications or the accompanying supplement.
• a variator for a vehicle that includes such a transmission
• a propulsion system for a vehicle that includes such a transmission
• Fig. 1 is a schematic representation of a variator (elsewhere referred to as an CVP) configuration for a first embodiment of the teachings of the invention
• Fig. 2 is a schematic cutaway view of the variator depicted schematically in Fig. 1;
• Fig. 3 is a schematic transmission diagram for a first embodiment of the present invention.
• Fig. 4 is a schematic transmission diagram for a second embodiment of the present invention.
• Fig. 5 is a schematic representation of an illustrative geometry for an external mesh
• Fig. 6 is a schematic representation of an illustrative geometry for an internal mesh
• Fig. 7 is a schematic representation of a variator that may be configured for use as an infinitely variable transmission (IVT);
• Fig. 8 is a schematic representation of another variator that may be configured for use as an IVT.
• Figs. 9 to 12 are schematic representations of various illustrative variator cone arrangements
• CVTs continuously variable transmissions
• IVTs Infinitely variable transmissions
• Continuously and infinitely variable transmissions are commonly used in such applications as vehicle primary and auxiliary transmissions, and industrial drives.
• Variators are devices that can be used to provide a continuously variable transmission.
• the most common way of achieving an infinitely variable transmission is to couple a variator with differential gearing.
• certain variators have been previously proposed in configurations that provide an infinitely variable transmission without requiring any additional gearing [see for example WO 2011/109444 A1].
• Multi-Continuously Variable Planetary (MCVP) hybrid transmission CVT/IVT
• MCVP novel multiple-input variator
• the MCVP is a planetary transmission with multiple planets that are double conical surfaces whose rotational axes are inclined relative to the main variator rotational axis - in an envisaged arrangement at an angle equal to the half cone angle, as shown in Error! Reference source not found, below.
• the general arrangement of an MCVP provides two surfaces that are parallel to the main axis.
• Axial shifting of a central disc 20 along an inside surface provides a sun branch with variable speed ratio; and axial shifting of an outer annulus along an outside surface provides a branch with variable speed ratio.
• the speed ratio is changed by virtue of changing the contact radius on the conical surfaces by axial shifting of a sun or annulus that contacts one of the said surfaces parallel to the main axis.
• the two variable branches in other arrangements may be two variable annuli (as depicted in Fig.12) or two variable suns (as depicted in Fig.12).
• the two variable branches of a particular MCVP configuration may be controlled independently of each other.
• the two variable branches may be coupled to two independent sources of motive power, or two independent power sinks (otherwise termed loads).
• loads For instance, a prime mover or a flywheel being discharged may be considered as sources of motive power.
• a vehicle driven axle or a flywheel being charged may be considered as power sinks or loads.
• the arrangement shown in Fig.1 and Fig.2 provides two surfaces that are parallel to the main axis; one corresponds to a variable annulus, one corresponds to a variable sun.
• Axial shifting of a central disc 20 along the inside surface provides a sun branch with variable speed ratio to control the flywheel, and axial shifting of an outer annulus along the outside surface provides a branch with IVT functionality for example for the vehicle final drive.
• Fig 2 is a schematic representation of a MCVP configured as in Figure 1 where the constant annulus branch is fixed to ground.
• the final drive of the vehicle is connected to the variable annulus shaft, which gives IVT potential (including reverse, with the bias of the ratio spread being chosen to suit the application by suitable design selection of the MCVP radii shown in Fig. 1).
• a different branch may be fixed to ground (such as the carrier 9, for example, corresponding to a CVT arrangement), or all branches may be rotatable (such as in section 3).
• All branches may be rotatable (such as in section 3).
• Other embodiments that provide IVT functionality without any additional gearing are shown in section 6.
• the MCVP arrangement shown in Fig. 2 uses planets where the cones face base to base on the planet shaft; this is also shown in Fig. 9.
• the two cones may also be arranged such that they may face tip to tip (as shown in Fig. 10) or in the same direction.
• the former arrangement would allow the diameter of the constant annulus to be reduced (which reduces the rotational stresses for the same shaft angular speed), the latter would mean that either both of the sun branches would be variable (as shown in Fig. 12) or both of the annuli branches would be variable (as shown in Fig. 11).
• Planets may be inclined at an angle that is deliberately greater or smaller than the half cone angle so that an increasing interference as the contact disc/annulus moves in a direction of increasing (steady state) torque (i.e. reduction in speed output shaft speed, and hence increase in torque for the same power).
• This is a passive system, meaning it does not require any external control.
• Another passive method would be elastically straining the disc/annulus that make traction contact with the conical planets, where this strain creates further interference and hence generates normal pressure on the fluid which increases with applied torque.
• the system may be bi-directional so that two similar mechanisms are used to act in opposite directions to create pressure from reversing torque. There would be backlash in this system as one mechanism relaxes whilst the other tenses when the direction of torque reverses.
• a prime mover is connected to the constant sun shaft 1 , to which is attached a bevel gear 2 (the constant sun gear) which meshes with a set of planet bevel gears 3 which are located in this arrangement at the axial centre of the planet 4 (one for each planet).
• Also on each planet 4 is another bevel gear 5 which meshes with an internal bevel gear 6, which is the constant annulus shaft (non-rotational in this arrangement since this branch is fixed to the casing 7).
• bevel gears on the planets can be positioned in various places along the planet axis, such as between the cones 8 as shown or either side to achieve the same functionality and that the choice will ultimately be made by the constraints of the assembly.
• the planets are supported in a planet carrier 9 using bearings 10, said carrier being free to rotate in this arrangement, but may be used as an input/output shaft in another arrangement.
• variable sun shaft 11 which is supported by bearings 12, 13 in the carrier 9 and constant sun shaft 1 respectively.
• the constant sun shaft 1 may be supported by bearings 14 in the carrier 9 which is in turn supported by bearings 15 in the hollow variable annulus shaft 16.
• the variable annulus shaft 16 is geared to the final drive of the vehicle.
• the variable annulus shaft 16 is supported by bearings 17 in the casing 7.
• variable annulus shaft 16 requires a mechanism allowing axial shifting of the annulus 19 making traction contact with the planet cone 7 in order to change the speed ratio between the prime mover and the vehicle.
• variable sun shaft 11 also requires a mechanism to axially shift the variable sun disc 20 in order to change the speed of the flywheel relative to the prime mover/vehicle.
• These two variable branches may utilise methods employed in the Turbo Trac variator (patent nos. US6001042 & US7856902) to facilitate this ratio control.
• the bevel gears 2,3,5,6 may be spiral bevel gears to reduce noise and vibration and provide smooth torque transfer and increased fatigue life for the gear teeth and surfaces.
• Klingelnberg spiral bevel gears (where the teeth are not tapered) in particular may be used which can be generated with a hobbing process much like automotive gearboxes and hence benefit from low cost in volume production despite their seemingly complex geometry.
• Palloid tooth form may also be produced by hobbing but has greater bending strength since the teeth are tapered.
• Fig. 3 is a schematic representation of a first transmission arrangement that employs a variator as described above.
• the variable annulus shaft 16 is hollow, allowing the constant sun shaft 1 to pass through coaxially on the same side of the CVP 28, being connected to the prime mover 29 via a gearbox 30 and a clutch 31.
• This arrangement conveniently allows the differential 32 to be placed in the middle of the vehicle's powered axle, between the prime mover 29 and the MCVP 28, since this is permitted by the relative sizing of the prime mover, MCVP and a flywheel 33.
• the prime mover 29, gearbox 30 and clutch 31 may be a standard automotive or motorbike engine and gearbox arrangement 34 with the included clutch 31.
• the flywheel 33 is connected to the variable sun shaft 11 via a clutch 35 and a gear box 36; order of said clutch and gearbox in the torque path is chosen for ease of component design/selection.
• the gearbox 36 may be a single fixed ratio, or a plurality of selectable ratios in order to behave as a ratio range extender for the flywheel branch of the MCVP, which arrangement will be immediately apparent to those of ordinary skill in the art.
• the range extender may have capability to change gear without torque interruption (such as, but not limited to, dual- or multiple-clutch gearboxes) so as to allow continuous charging and discharging of the flywheel over a large range of vehicle/prime mover speeds.
• flywheel gearbox does reverse the direction of rotation, then this can be counteracted by first ensuring the flywheel is in the correct orientation to rotate oppositely to the wheels, then selecting a gearing arrangement that will ensure the correct direction of shaft rotation at the vehicle wheels, whilst ensuring the drive from the prime mover is also in the correct rotational direction.
• the MCVP described above is a dual ratio-controlled planetary variator that can also operate in a (quasi-)torque-controlled mode.
• This mode is achieved by virtue of its similarities with the conventional planetary gear set (comprising a sun gear and shaft, an annulus internal gear and shaft, both of said gears mesh with a set of planet gears located in the planet gear carrier connected to a carrier shaft), which is known to be used as a torque-splitting device in transmissions.
• the conventional planetary gear set comprising a sun gear and shaft, an annulus internal gear and shaft, both of said gears mesh with a set of planet gears located in the planet gear carrier connected to a carrier shaft
• the conventional planetary gear set comprising a sun gear and shaft, an annulus internal gear and shaft, both of said gears mesh with a set of planet gears located in the planet gear carrier connected to a carrier shaft
• the conventional planetary gear set comprising a sun gear and shaft, an annulus internal gear and shaft, both of said gears mesh
• three branches of the MCVP are used: the carrier, one of the annuli/rings and one of the suns. These three branches make up a conventional planetary arrangement, but here the planetary (or epicyclic) ratio is continuously variable.
• the flywheel, the prime mover and the vehicle Final drive are each connected to a different branch. Clutches may be used to vary which of the branches the prime mover, flywheel and vehicle are connected to, depending on the mode of operation.
• Actuation of one (or both) of the ratio control mechanisms can change the planetary ratio and thus adjust the torque split.
• Each branch will accelerate depending on the torque applied to it (whilst obeying the linear speed relationship), thus facilitating torque control.
• the transmission system is controlled by controlling the engine torque in conjunction with the planetary ratio, in response to driver inputs or road conditions. In this mode, the vehicle speed depends on both the engine and flywheel speeds.
• any planetary variator may be employed to form this torque- controlled transmission (including but not limited to the NuVinci CVP, the Kopp variator and the Milner CVT).
• the MCVP described herein may be a traction drive, where a thin film of traction fluid is sheared between the contacts.
• a friction drive i.e. dry running metal-metal contact
• TurboTrac patents US6001042 and US7856902 each describe mechanisms for controlling variator ratios and methods for providing the necessary normal contact forces for traction/friction drives.
• any of the constant ratio sun and annulus branches 2,6 can comprise bevel gears or bevel traction surfaces.
• Fig. 5 for an external mesh (two convex bodies 2,3 - corresponding to a constant ratio sun branch 2 for an MCVP) and in Fig. 6 for an internal mesh (one concave body 6 and one convex body 5 - corresponding to a constant ratio annulus branch 6 for an MCVP).
• This is achieved by selecting appropriate cone angles 52,56 such that a line 54 through the gear mesh (defined by the intersection of the contact tangent plane and a radial plane defined by the two axes 51 ,53) and the two respective rotational axes 51 ,53 all intersect at a the same point 55.
• any axial thickness can be selected to obtain a desired contact fatigue life.
• a crown radius may also be provided on each surface if a traction contact is employed.
• the bevel gears/traction surfaces 3, 5 on the planet may be different features. In another embodiment, the bevel gears/traction surfaces 3, 5 on the planet may be the same feature, meaning that they will have the same bevel angle 56. 6.
• IVT functionality Various arrangements with IVT functionality
• An MCVP 28 can be configured in numerous ways to provide an infinitely variable transmission (IVT) without needing to couple to a conventional planetary gear set. In general this is achieved by rotating the planet carrier 9, and using two annulus branches (or alternatively two sun branches), at least one of which is a variable ratio branch, grounding one annulus (or sun) branch, with the speed of the other annulus (or sun) branch found by summing the linear velocities of the planet and the carrier at the point of contact; if suitable geometry is chosen, at one point along the actuation cone 58 these two linear velocities will sum to zero.
• a beneficial feature of this kind of IVT is that no recirculating power exists.
• a further beneficial feature of the MCVP device is that the axial position of the variable ratio branch at which the geared neutral condition is reached can be freely selected; allowing free control of how the ratio spread is shared between forwards and reverse.
• a constant ratio annulus branch 6 and a variable ratio annulus branch 19 are employed to provide the IVT functionality.
• the planet axis 51 rotates about the main axis 53, meaning the planets orbit within the device, and either one of the annulus branches 6,19 is irrotational (fixed to ground) and the other is used as a transmission output.
• the MCVP carrier 9 must rotate to provide an IVT without additional gearing.
• the input to the transmission may be, for example, the carrier 9 or any opposing branch to the grounded branch (a sun and an annulus are opposing branches to each other).
• Some possible combinations of grounded branch and IVT output branch (possessing geared neutral) are shown in the table below:
• these combinations may be used to construct an MCVP that functions as a standalone launch device for a vehicle, providing an efficient IVT without power recirculation.
• the cones 58 of the MCVP may face in opposite directions or in the same direction (generating either two variable suns or two variable annuli).
• Various different configurations are shown in Figs. 9 to 12.
• This invention relates to transmission systems, particularly but not exclusively to transmission systems for vehicles. Another aspect of the invention relates to a variator for such a transmission system.
• a further concern is that the amount and nature of engine emissions tend to vary considerably over the range of operating conditions experienced by the engine. Larger trucks, buses, lorries and off-highway vehicles tend to have larger diesel engines that typically produce peak emissions when under transient operating conditions, and as a consequence the performance of new engines of this type tends to be compromised in the design stage in order to meet increasingly stringent emissions regulations.
• the engine can also be switched off when the vehicle is temporarily stationary (for example, at traffic lights) - responsive vehicle behaviour when pulling away from standstill being provided by the motor-generators.
• series hybrids of the type described above generally do not add power capability, they can improve efficiency (under the right conditions).
• series hybrids tend to be expensive to produce due to the significant added cost of the electric motors and batteries, and the additional weight that such devices add to a typical vehicle also impacts upon performance and efficiency.
• the batteries themselves are also an environmental concern and are costly even in mass production, due to the materials and processes required in manufacture.
• Another important drawback of such systems is that power flow through the powertrain requires multiple energy conversions (between chemical, potential, mechanical, kinetic and electrical forms) and resultant energy losses.
• a further proposal is the so-called mechanical hybrid, such as those incorporating lightweight high-speed flywheels (such as those by Flybrid Systems, see www.flvbrid.co.uk ' ).
• the Flybrid systems are effectively "bolt on” devices that provide for kinetic energy recovery (regenerative braking), and are designed to interface with conventional powertrain architecture that comprises a clutch, a discrete gearbox and a differential.
• the hybrid component of the Flybrid system comprises a flywheel, a fixed gear stage, a clutch and a continuously variable transmission (CVT).
• Both of the aforementioned systems are so-called “parallel hybrid” systems that are capable of propelling the vehicle by means of a prime mover (such as an internal combustion engine) or the flywheel or a combination of both.
• the aforementioned systems also have "full hybrid” capability in that they can accept a proportion of surplus SUPPLEMENT 16
• a variator (otherwise referred to as an MCVP) comprising a first and a second cone, said cones being rotatable about a common axis that is inclined relative to a main axis so that said first and second cones each provide a side that is substantially parallel to said main axis.
• Protection is also claimed for a cone substantially as herein described, an MCVP as herein described, a vehicle transmission, and a vehicle incorporating an MCVP.
• Fig. 1 is a schematic representation of two truncated cones arranged along a common axis in a first configuration
• Fig. 2 is a schematic representation of alternative cone configurations
• Fig. 3 is another schematic representation of another cone configuration
• Fig. 4 is a schematic planetary analogy of an illustrative variator
• Fig. 5 is a schematic representation of an illustrative vehicle transmission
• Fig. 6 is a schematic representation of an arrangement that is functionally equivalent to the arrangement depicted in Fig. 5;
• Figs. 7(a) to 7(h) are schematic representations of several possible power paths.
• Fig. 8 is a schematic representation of an illustrative variator configuration
• Fig. 9 is a cut-away schematic representation of the variator depicted in Fig. 8; SUPPLEMENT
• Fig. 10 is a diagrammatic representation of a transmission system that incorporates the variator depicted in Figs. 8 or 9;
• Fig. 11 is a rendered image of the variator depicted in Figs. 8 and 9 in use with a prime mover and a flywheel.
• the system disclosed herein entirely replaces a conventional stepped (discrete gearbox) transmission.
• the system disclosed herein embodies the benefits of both series and parallel hybrid powertrains, in particular: increased power capability beyond that of the prime mover alone (parallel hybrid), and permitting the engine to operate entirely independently of the instantaneous vehicle requirements and thus achieve greater efficiency (series hybrid).
• the transmission system disclosed herein is used in conjunction with a prime mover (for example an internal combustion (IC) engine) and a flywheel.
• a prime mover for example an internal combustion (IC) engine
• a flywheel can be used to supply kinetic energy whilst also simultaneously accepting power from the prime.
• the flywheel thus acts as a buffer by being able to accept surplus engine power
• the system disclosed provides numerous additional useful modes of operation that are beneficial in a wide variety of ground vehicle applications.
• the system provides infinitely variable transmission (IVT) functionality (with reverse gear) for the final drive, with the flywheel being able to be charged with the prime mover power even whilst the wheels are in a powered neutral mode (where this energy is normally wasted as heat in power recirculation). It is also possible to start the engine with the flywheel if desired.
• IVTT infinitely variable transmission
• control strategies are also possible, which can be optimised for energy efficiency.
• CVT continuously variable transmission
• the ability to actuate two distinct mechanisms as provided in the system disclosed herein is equivalent to having two independent CVTs within one component, allowing the ability to independently choose an appropriate speed ratio for two different means of propelling a vehicle. This is useful in a multitude of applications, but is especially important for flywheel hybrids.
• the speed of the flywheel inherently changes during energy transfer (control of the flywheel speed controls the energy storage and recovery), since for a given flywheel inertia, the energy stored is purely a function of rotational speed; thus independent control of flywheel speed from the engine and the wheels is important.
• the novel CVT described herein may be referred to as a Multi- Continuously Variable P netary (or MCVP) due to its similarities to a planetary gear set and the aforementioned NuVinci CVP.
• the MCVP differs, however, from the NuVinci CVP by having more than one actuation mechanism. Providing more than one actuation SUPPLEMENT
• the MCVP disclosed herein provides significantly higher transmission efficiencies than two CVTs in which some power paths involve crossing two CVTs (equating to 4 traction contacts in series).
• traction contacts in parallel add linearly to the torque capacity of a CVT, but traction contacts in series reduce efficiency with a multiplicative relationship.
• the MCVP benefits from both of these facts. There is also the benefit of reduced mass and component count (and hence cost) owing to the same components contributing to both CVT mechanisms.
• the transmissions disclosed herein are not limited to use in vehicles.
• the transmissions disclosed herein are not limited to vehicles or machinery where the primary source of power is an internal combustion engine.
• most motor devices whether combustion engines, electric machines, hydraulic motors etc) have regimes of operation where they are most efficient, and benefit from the properties gained from using the system disclosed herein.
• the term "prime mover" is used here to not restrict the invention to (C engines, since the system is equally suited to any motor device.
• the MCVP disclosed herein comprises a novel planetary traction drive (depicted schematically in Fig. 1 below) that employs planets which are double truncated cones inclined at an angle to the main shaft axis that is equal to half of the cone angle, thereby producing two effective straight edges aligned parallel to the main axis.
• Two independent actuator mechanisms control the axial position of a disc and a ring (green contact patches) that make contact with the inner and outer effective edges of the planet, which changes the contact radius on the planet and thus the linear speed, thereby changing the rotational speed of the said disc and ring.
• the ring and the disc rotate about the main rotational axis.
• One other "disc” and one other “ring” also make contact and provide a means of clamping the planet on all sides and a means for supplying pressure (for example, hydraulic/sprung etc) to induce elasto-hyrdrodynamic conditions in the contact fluid for efficient torque transfer.
• the planets themselves are mounted via bearings seated on the cylindrical parts of the truncated cones into a carrier which can also rotate about the main axis.
• the red contact points which are constrained from moving axialiy can be replaced with toothed gears (depicted schematically in Fig. 3 below) in between the two cones in order to increase mechanical efficiency (although SUPPLEMENT
• MCVP may be employed in a vehicle transmission that couples two at least two sources of motive power to one or more driven elements (such as a pair of wheels on an axle).
• Fig. 5 below is a schematic representation of one such SUPPLEMENT 22
• MCVP MCVP
• first and second sources of motive power in this illustrative example, a flywheel (labelled “FW”); a prime mover (labelled “PM”) such as, inter alia, a combustion engine, an electric machine or a hydraulic machine)), and a differential (labelled "Diff”) that is coupled to a pair of driven wheels on a braked axle.
• FW flywheel
• PM prime mover
• Diff differential
• the flywheel is connected to the variable "sun" branch of the MCVP
• the prime mover is connected to the constant "sun” branch
• the final drive is connected to the variable "ring” branch
• the constant ring branch is fixed to ground (no rotation).
• the carrier is necessarily free to rotate.
• the flywheel and the prime mover are connected to their respective branches by means of a clutch (as shown) and a fixed ratio gear stage (not shown) may also be provided before or after the clutch in order to be at the right speed in the transmission.
• the prime mover can be switched on and the prime mover clutch can be engaged and fully closed which causes the constant sun branch to rotate and also defines the speed of the carrier branch, since the constant ring branch is fixed to ground.
• the prime mover clutch can be engaged and fully closed which causes the constant sun branch to rotate and also defines the speed of the carrier branch, since the constant ring branch is fixed to ground.
• variable planet gear in contact/mesh with the variable speed output ring When the diameter of the variable planet gear in contact/mesh with the variable speed output ring is the same as the diameter of the constant planet gear in contact/mesh with the grounded ring, the final drive is in a powered neutral condition.
• the prime mover is rotating and supplying power, but the final drive is locked stationary.
• IVT Intelligent Variable Transmission
• any external torque exerted at the vehicle wheels will not cause the vehicle to move, such as in the case of being stationary on an inclined surface. Additionally, this means there is no need for a pulling- away clutch, reducing the number of components required.
• the final drive direction of rotation reverses either side of the powered neutral condition, providing the means for a reverse gear.
• the ratio spread either side of powered neutral can be adjusted to favour forward motion if desired by changing the diameter of the constant ring and planet gears.
• a key function offered in this mode is that other branches of the system remain rotational, and actuation of the other ratio control mechanism provides continued functionality for that respective branch independent of the powered neutral condition of the final drive. This allows the flywheel to be charged with the engine power by actuating the other ratio mechanism so as to increase the flywheel speed.
• the flywheel can conveniently continue to subtract torque to prevent this from happening (traction control system increases flywheel torque if wheels begin to slip).
• Fig. 6 The arrangement shown schematically in Fig. 6 is functionally equivalent to the arrangement depicted in Fig. 5, and from this it is perhaps easier to visualise how simultaneous regenerative braking and engine charging of the flywheel is possible.
• Fig. 6 also shows two variators (the CVT and IVT) in the box that represents the MCVP in preferred configuration. If, instead of the aforementioned MCVP, two separate CVTs were used, a regenerative braking path would have to cross two CVTs per one way trip, and as such "round trip" power would have to cross four CVTs - an arrangement that is not particularly efficient. The arrangement described herein only effectively crosses one CVT per one-way trip (hence only two per round trip) and as a consequence is more efficient.
• the MVCP disclosed in the application has several operating modes, and schematic representations of the respective power paths SUPPLEMENT 25
• Fig. 9 is an illustration of a variator configured as shown schematically in Fig. 8 where the constant annulus branch is fixed to ground.
• the final drive of the vehicle is connected to the variable annulus shaft, which gives IVT potential (including reverse, with the bias of the ratio spread being chosen to suit the application by suitable design selection of the variator radii shown in Figure 8).
• the particur implementation shown in Figure 9 employs planets where the cones face base to base on the planet shaft.
• the two cones may, in another envisaged implementation, be arranged such that they may face tip to tip or in the same direction.
• the former arrangement would allow the diameter of the constant annulus to be reduced (which reduces the rotational stresses for the same shaft angular speed), the latter would mean that either both of the sun branches or both of the annuli branches would be variable.
• Planets may be inclined at an angle that is deliberately greater or smaller than the half co e angle so that an increasing interference as the contact disc/annulus moves in a direction of increasing (steady state) torque (i.e. SUPPLEMENT 36
• This is a passive system, meaning it does not require any external control.
• Another passive method would be elastically straining the disc/annulus that make traction contact with the conical planets, where this strain creates further interference and hence generates normal pressure on the fluid which increases with applied torque.
• the system may be bi-directional so that two similar mechanisms are used to act in opposite directions to create pressure from reversing torque. There would be backlash in this system as one mechanism relaxes whilst the other tenses when the direction of torque reverses.
• the prime mover is connected to the constant sun shaft 1 , to which is attached a bevel gear 2 (the constant sun gear) which meshes with a set of planet bevel gears 3 which are located in this embodiment at the axial centre of the planet 4 (one for each planet). Also on each planet A is another bevel gear 5 which meshes with an internal bevel gear 6, which is the constant annulus shaft (non-rotational in this embodiment since this branch is fixed to the casing 7). It will be appreciated by those experienced in the art that the bevel gears on the planets can be positioned in various places along the planet axis, such as between the cones 8 as shown or either side to achieve the same functionality and that the choice will ultimately be made by the constraints of the assembly.
• the planets are supported in a planet carrier 9 using bearings 10. The carrier is free to rotate in this particular implementation, but may be used as an input/output shaft in other implementations.
• variable sun shaft 11 which is supported by bearings 12, 13 in the carrier 9 and constant sun shaft 1 respectively.
• the constant sun shaft 1 may be supported by bearings 14 in the carrier 9 which is in turn supported by bearings 15 in the hollow variable annulus shaft 6.
• the variable annulus shaft 15 is geared to the final drive of the vehicle.
• the variable annulus shaft 16 is supported by bearings 17 in the casing 7.
• variable annulus shaft 6 requires a mechanism allowing axial shifting of the annulus 19 making traction contact with the planet cone 7 in order to change the speed ratio between the prime mover and the vehicle.
• variable sun shaft 11 also requires a mechanism to axially shift the variable sun disc 20 in order to change the speed of the SUPPLEMENT 37
• variable branches may utilise techniques such as those employed in the Turbo Trac variator (see patent nos. US6001042 & US7856902) to facilitate this ratio control.
• the bevel gears 2, 3, 5 and 6 may be spiral bevel gears to reduce noise and vibration and provide smooth torque transfer and increased fatigue life for the gear teeth and surfaces.
• Klingelnberg spiral bevel gears (where the teeth are not tapered) in particular may be used which can be generated with a hobbing process much like automotive gearboxes and hence benefit from low cost in volume production despite their seemingly complex geometry.
• Palloid tooth form may also be produced by hobbing but has greater bending strength since the teeth are tapered.
• Figure 10 is a schematic representation of a transmission that incorporates the variator of Figs. 8 and 9.
• the variable annulus shaft 16 is hollow, allowing the constant sun shaft 1 to pass through coaxially on the same side of the variator 28, being connected to the prime mover 29 via a gearbox 30 and a clutch 31 .
• This arrangement conveniently allows the differential 32 to be placed in the middle of the vehicle's powered axle, between the prime mover 29 and the variator 28, since this is permitted by the relative sizing of the prime mover, variator and flywheel.
• the prime mover 29, gearbox 30 and clutch 31 may be a standard automotive or motorbike engine and gearbox arrangement 34 with the included clutch 31.
• the flywheel 33 is connected to the variable sun shaft 11 via a clutch 35 and a gear box 36; order of said clutch and gearbox in the torque path is chosen for ease of component design/selection.
• the gearbox 36 may be a single fixed ratio, or a plurality of selectable ratios in order to behave as a ratio range extender for the flywheel branch of the variator, which can be appreciated by those skilled in the art.
• the range extender may have the capability to change gear without torque interruption (such as, but not limited to, dual or multiple clutch gearboxes) so as to allow continuous charging and discharging of the flywheel over a large range of vehicle/prime mover speeds.
• Mechanical brakes 37 can bring the vehicle safely to rest in event of failure of 5 any control critical components in the transmission.
• the flywheel and prime mover clutches 35, 31 are simply disengaged in order to stop supply of power to the vehicle.
• Fig. 1 1 is a schematic re resentation of a variator of the type disclosed herein mated with a 4-stroke 250CC prime mover and a flywheel.
• Mass savings may be made by effectively providing two CVTs in one assembly with common components shared between them.
• Planetary gear set similarities provide improved functionality as compared to existing planetary multiple input CVTs by adding at least one extra "branch” (5 in total), with two suns and two rings. Providing two similar type of branches e.g. suns is very useful and provides an improved choice of ratios and configurations (even in conventional one input / one output form) and by having independent ratio control.
• IVT powered neutral possible with other shafts than engine remaining active and other ratio mechanism operational, so another component can be powered or a flywheel charged rather than wasting energy in power recirculation.
• Figure 1 Drive cycle of an endurance lap shewing cumulative braking
• the NuVinci CVP typically has a ratio
• Figure 2 Energy saving relative to a 240kg baseline conventional range from 0.5 to 2.0 whereas the Milner CVT can have vehicle (with 70kg driver) a ratio range from around 0 6 to 3.8 [4][6].
• Figure 2 shows the energy saving on the endurance
• the NuVinci CVP has two effective annuli branches, a packaging of the vehicle. sun and a planet carrier.
• the system uses a high-speed
• flywheel connected to the vehicle transmission via a
• CVT full-toroidal variator
• MULTIPLE-INPUT PLANETARY VARIATORS vehicle must be connected to a vehicle final drive.
• the Milner CvT changes the ratio between all branches.
• variable gear radii shown in Figures 3 and 4 all of the variable gear radii shown in Figures 3 and 4 all of the variable gear radii shown in Figures 3 and 4 all of the variable gear radii shown in Figures 3 and 4 all of the variable gear radii shown in Figures 3 and 4 all of the variable gear radii shown in Figures 3 and 4 all of the variable gear radii shown in Figures 3 and 4 all of the variable gear radii shown in Figures 3 and 4 all
• the MCVP is a new planetary traction drive using
• the system behaves like an electric series hybrid, in that
• the system can be melted down and the
• Figure A1 Conventional geared-neutral mode (power recirculated & dissipated as heat)
• Figure A3 Surplus prime mover power (including traction-limited acceleration)

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• 2012
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