The NuVinci Continuously Capricious Manual is a blazon of roller-based continuously capricious manual (CVT) bogus and marketed by the American aggregation Fallbrook Technologies Inc. The architecture saw its antecedent bazaar appliance as bike gearing system, aboriginal accessible in December 2006 in the Netherlands. NuVinci CVTs are aswell currently beneath development for added applications, including wind turbines, ablaze electric vehicles, alfresco ability equipment, and automotive front-end accent drives.
Friday, 23 March 2012
Technical
The NuVinci CVT accessory arrangement uses a set of alternating and angry assurance positioned amid the ascribe and achievement discs of a transmission. Angry the assurance changes their acquaintance diameters and varies the acceleration ratio.23 As a result, the NuVinci CVT arrangement offers seamless and connected alteration to any arrangement aural its range. The accessory arrangement is confused by angry the axes of the spheres in a connected fashion, to accommodate altered acquaintance radii, which in about-face drive ascribe and achievement discs. The arrangement has assorted "planets" to alteration torque through assorted aqueous patches. The spheres are placed in a annular arrangement about a axial idler (sun) and acquaintance abstracted ascribe and achievement absorption disks. This agreement allows ascribe and achievement to be concentric and compact. The aftereffect is the adeptness to ambit the manual through the absolute arrangement ambit smoothly, while in motion, beneath load, or stopped.
Two factors acquiesce the NuVinci CVT to accommodate a continuously capricious arrangement ambit in a bunched package:
The aboriginal is the geometric agreement of the drive, which is based on differing acquaintance arrangement of a sphere. Contacting a alternating apple at two altered locations about to the sphere’s rotational arbor will accommodate a “gear ratio”, which can ambit from underdrive to overdrive depending on the area of the acquaintance credibility for ascribe and achievement torque and speed.2
The additional agency is elastohydrodynamic lubrication (EHL).4 Transmissions that use EHL to alteration ability are accepted as absorption drives. A absorption drive manual operates utilizing a absorption aqueous that, beneath accustomed circumstances, provides lubrication for the drive. When this aqueous undergoes top acquaintance pressures beneath rolling acquaintance amid the two actual harder elements, the spheres and the disks, the aqueous undergoes a near-instantaneous appearance change to an adaptable solid. Aural this application of absorption the molecules of the aqueous assemblage up and hotlink to anatomy a solid, through which microburst force and appropriately torque can be transferred. Note that the rolling elements are in fact not in concrete contact.2
Two factors acquiesce the NuVinci CVT to accommodate a continuously capricious arrangement ambit in a bunched package:
The aboriginal is the geometric agreement of the drive, which is based on differing acquaintance arrangement of a sphere. Contacting a alternating apple at two altered locations about to the sphere’s rotational arbor will accommodate a “gear ratio”, which can ambit from underdrive to overdrive depending on the area of the acquaintance credibility for ascribe and achievement torque and speed.2
The additional agency is elastohydrodynamic lubrication (EHL).4 Transmissions that use EHL to alteration ability are accepted as absorption drives. A absorption drive manual operates utilizing a absorption aqueous that, beneath accustomed circumstances, provides lubrication for the drive. When this aqueous undergoes top acquaintance pressures beneath rolling acquaintance amid the two actual harder elements, the spheres and the disks, the aqueous undergoes a near-instantaneous appearance change to an adaptable solid. Aural this application of absorption the molecules of the aqueous assemblage up and hotlink to anatomy a solid, through which microburst force and appropriately torque can be transferred. Note that the rolling elements are in fact not in concrete contact.2
Comparison to Conventional Transmissions
The NuVinci CVT arrangement has few parts.27
Since any CVT may acquiesce a adeptness plant, animal or motorized, to accomplish at (or afterpiece to) the dispatch at which its efficiency, achievement torque or achievement adeptness is optimal, the NuVinci CVT may advance a system's all-embracing adeptness or achievement compared to if a 'conventional' geared manual were used, but alone if such accretion in the adeptness or achievement of the adeptness bulb exceeded any accident in adeptness or achievement that may be alien by replacing the accepted manual with the NuVinci CVT. For example, if the NuVinci CVT were alone 85% as able as the accepted manual it replaced, the accretion in operating adeptness from the adeptness bulb would acquire to be 18% (i.e., 1/0.85 - 1 = 0.18 or 18%) afore the all-embracing adeptness improved.
The NuVinci CVT added offers the adeptness to acquire assorted inputs while capricious dispatch and ratio, managing torque and accouterment individual or assorted adeptness outlets. By acknowledging a torque-demand rather than a speed-demand ascendancy solution, the NuVinci CVT solves the low-speed dispatch botheration inherent in some torque-demand vehicles.2
The NuVinci CVT is simple architecture and low allotment calculation accomplish it calmly scalable, with applique that can be acclimated beyond a advanced array of applications.
Since any CVT may acquiesce a adeptness plant, animal or motorized, to accomplish at (or afterpiece to) the dispatch at which its efficiency, achievement torque or achievement adeptness is optimal, the NuVinci CVT may advance a system's all-embracing adeptness or achievement compared to if a 'conventional' geared manual were used, but alone if such accretion in the adeptness or achievement of the adeptness bulb exceeded any accident in adeptness or achievement that may be alien by replacing the accepted manual with the NuVinci CVT. For example, if the NuVinci CVT were alone 85% as able as the accepted manual it replaced, the accretion in operating adeptness from the adeptness bulb would acquire to be 18% (i.e., 1/0.85 - 1 = 0.18 or 18%) afore the all-embracing adeptness improved.
The NuVinci CVT added offers the adeptness to acquire assorted inputs while capricious dispatch and ratio, managing torque and accouterment individual or assorted adeptness outlets. By acknowledging a torque-demand rather than a speed-demand ascendancy solution, the NuVinci CVT solves the low-speed dispatch botheration inherent in some torque-demand vehicles.2
The NuVinci CVT is simple architecture and low allotment calculation accomplish it calmly scalable, with applique that can be acclimated beyond a advanced array of applications.
Comparison to other CVTs
The NuVinci uses rolling absorption to alteration torque, just as do toroidal transmissions. However, clashing toroidal CVTs, it distributes the transmitted torque over several spheres, appropriately blurred absolute anchor force required.
This adjustment allows the NuVinci CVT to amalgamate the smooth, connected ability alteration of a CVT with the account of a accepted all-embracing accessory drive.
As with added traction-type CVTs, manual of torque through the NuVinci CVT involves some about sliding amid the torque-transmitting acquaintance patches.8 This is because, for any accustomed acquaintance patch, locations of the brawl are traveling in a hardly altered administration and at hardly altered speeds than the disc (this abnormality of traction-type CVTs is referred to as "contact spin"). "The circuit acceleration (or assignment speed) is authentic as the aberration in the rotational acceleration of the active and apprenticed rollers in a administration erect to the acquaintance application plane. It is acquired by the about aberration in apparent speeds of both elements beyond the acquaintance application and is a above antecedent of ability accident in absorption drive CVT’s."9 In all traction-type CVTs, this about sliding necessarily occurs amid surfaces which are beneath the actual top anchor pressures appropriate to ensure torques are transmitted reliably. This about sliding beneath top pressures could cause manual losses (inefficiency). Fallbrook Technology debris to broadcast any ability abstracts for the NuVinci CVT.1011 However, The NuVinci is a alternative on the "Tilting-ball drive" blazon of continuously-variable manual (CVT), and the ability of "Tilting-ball drive" blazon CVTs is about in the ambit of 70% to 89%. 12 However, its geometry does alter decidedly from the Kopp blazon of angry brawl variator in the advertence in that the NuVinci has its torque alteration contacts on the alfresco bore rather than the central diameter.
Torque inputs can be summed or divided, just as in a accepted planetary.clarification needed Ratio ascendancy is stable, and can be actuated down the centermost band of the transmission, which afresh is agnate to the accurate all-embracing transmission. In a lot of applications, there is no charge for high-pressure hydraulics.
Other advantages aggregate with agnate CVT designs cover that the ascribe and achievement shafts may be either in-line, offset, or in a U agreement (input and achievement both coaxial and coplanar), authoritative the manual simple, small, ablaze and simple to package.
Fallbrook claims the manual ascendancy is stable, beeline and does not crave a above ascendancy arrangement development effort.
This adjustment allows the NuVinci CVT to amalgamate the smooth, connected ability alteration of a CVT with the account of a accepted all-embracing accessory drive.
As with added traction-type CVTs, manual of torque through the NuVinci CVT involves some about sliding amid the torque-transmitting acquaintance patches.8 This is because, for any accustomed acquaintance patch, locations of the brawl are traveling in a hardly altered administration and at hardly altered speeds than the disc (this abnormality of traction-type CVTs is referred to as "contact spin"). "The circuit acceleration (or assignment speed) is authentic as the aberration in the rotational acceleration of the active and apprenticed rollers in a administration erect to the acquaintance application plane. It is acquired by the about aberration in apparent speeds of both elements beyond the acquaintance application and is a above antecedent of ability accident in absorption drive CVT’s."9 In all traction-type CVTs, this about sliding necessarily occurs amid surfaces which are beneath the actual top anchor pressures appropriate to ensure torques are transmitted reliably. This about sliding beneath top pressures could cause manual losses (inefficiency). Fallbrook Technology debris to broadcast any ability abstracts for the NuVinci CVT.1011 However, The NuVinci is a alternative on the "Tilting-ball drive" blazon of continuously-variable manual (CVT), and the ability of "Tilting-ball drive" blazon CVTs is about in the ambit of 70% to 89%. 12 However, its geometry does alter decidedly from the Kopp blazon of angry brawl variator in the advertence in that the NuVinci has its torque alteration contacts on the alfresco bore rather than the central diameter.
Torque inputs can be summed or divided, just as in a accepted planetary.clarification needed Ratio ascendancy is stable, and can be actuated down the centermost band of the transmission, which afresh is agnate to the accurate all-embracing transmission. In a lot of applications, there is no charge for high-pressure hydraulics.
Other advantages aggregate with agnate CVT designs cover that the ascribe and achievement shafts may be either in-line, offset, or in a U agreement (input and achievement both coaxial and coplanar), authoritative the manual simple, small, ablaze and simple to package.
Fallbrook claims the manual ascendancy is stable, beeline and does not crave a above ascendancy arrangement development effort.
Applications
The NuVinci CVT may be applicative to abounding altered articles appliance a automated ability transmission. The alone appliance currently commercialized is the internally geared bike hub. The NuVinci CVT replaces derailleurs and added internally-geared hubs, and provides a accessory arrangement ambit of about 350%, agnate to that on bicycles with 8 or 9-speed hub gears, or with bifold alternation rings (most antagonism or fast alley bicycles).13 This ambit is somewhat beneath than the 526% ambit begin on bicycles with a Rohloff 14-speed hub accessory or a lot of mountain/hybrid/touring bicycles with amateur chainrings. By accepted standards, a NuVinci bike hub is advised heavy. The additional bearing archetypal N171B weighs amid 3.85 and 3.95 kilograms (8.5 and 8.7 lb), including freewheel and ascent hardware.14 The N360 archetypal appear aboriginal September 2010 weighs 2.45 kg (5.4 lb).15 That aforementioned commodity credibility out that "the accumulated weight of Shimano SLX foreground and rear derailleurs, shifters, freehub and cassette comes out to about 1.3 kg (2.9 lb)". However, the NuVinci CVT is targeted appear the beneath weight-conscientious (cruiser-, comfort-, and commuter) segments.
The aggregation is aswell developing articles based on the CVT assemblage for automotive applications
The aggregation is aswell developing articles based on the CVT assemblage for automotive applications
Awards and publicity
The arrangement and associated bicycles accept been the recipients of several awards. These cover Bicycling Magazine's Editor's Choice for Commuter Bike of the Year, 2010 EUROBIKE Award,16 2007 R&D 100 Awards, a 2007 Popular Science Best of What’s New, 2007 Technology of the Year and Bike of the Year in The Netherlands, and an iF Design EUROBIKE Gold 2008 Award. Bicycles able with NuVinci transmissions after won iF Design EUROBIKE awards in 2010 and 2011.
Ellsworth Handcrafted Bicycles, a architect of bike frames and auto advised a bike about the Nuvinci CVT. In 2007, The Ride accustomed top ceremoniousness in Popular Science magazine’s anniversary Best of What’s New analysis of cogent new products.17
Ellsworth Handcrafted Bicycles, a architect of bike frames and auto advised a bike about the Nuvinci CVT. In 2007, The Ride accustomed top ceremoniousness in Popular Science magazine’s anniversary Best of What’s New analysis of cogent new products.17
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