WITH VARIABLE DISK TRACTION DRIVE FIELD OF THE INVENTION

This invention relates to a variable disk friction drive used in a continuously variable transmission system suitable for use in an automotive transmission and other applications requiring a variable mechanical drive.

BACKGROUND TO THE INVENTION

The current invention relates to improvements over PCT patent publication numbers WO201 7143363 and WO2019239379 in the name of the same applicant. These improvements relate to simplifying the design in a new configuration to facilitate commercial development, eliminate thrust bearings and large bevel gears, and implement a loading cam to increase mechanical efficiency, while making it suitable for a variety of applications. BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is now described by way of example only and with reference to the accompanying drawings in which: FIGURES 1 A & 1 B illustrate perspective views of an assembled continuously variable transmission system according to the invention from two angles of rotation. FIGURE 2 is a perspective view of the transmission system of Figure 1 , but with the front casing 12 and rear casing 14 removed

FIGURE 3 is a sectional side elevation of the transmission system of Figure 2.

FIGURES 4A & 4B illustrate perspective views of a variator unit 16 from two angles of rotation.

FIGURES 5A & 5B illustrate perspective views from two angles of rotation of a structure unit 32.

FIGURES 5C & 5D illustrate perspective view of enlarged portions A of the structure unit 32. FIGURES 6A & 6B illustrate perspective views from two angles of rotation of a structure center 58.

FIGURE 6C is a sectional plan view of the structure centre 58 of Figures 6A &6B.

FIGURE 6D is a sectional side elevation of the structure centre 58 of Figure 6C.

FIGURE 7 A is an exploded perspective view of a radial shaft unit 60.

FIGURES 7B & 7C illustrate a perspective view and a sectional side elevation respectively of radial shaft unit 60 of Figure 7A. FIGURES 8A & 8B illustrate perspective views from two angles of rotation of a gear coupling unit 62.

FIGURE 8C is a sectional side elevation of the gear coupling unit 62 of Figures 8A, 8B. FIGURE 9A is a perspective view of ratio drive unit 64. FIGURE 9B is a perspective view of second shaft arrangement used in the ratio drive unit 64 of Figure 9A, but from an opposite angle of rotation.

FIGURES 10A & 10B illustrate perspective views from two angles of rotation of a structure body 56.

FIGURE 11 is a sectional elevation of the structure body 56 of Figures 10A, 10B.

FIGURE 12 is a perspective view of an oil pump 66. FIGURES 13A & 13B illustrate perspective views from two angles of rotation of a follower unit 30.

FIGURE 13C is a perspective view of a driver, which is located inside the follower body 318 of the follower unit 30 of Figures 13A, 13B.

FIGURE 13D is a sectional side elevation of the follower unit 30 of Figure 13A.

FIGURE 14 is a perspective view of front spiral 26.

FIGURES 15A & 15B illustrate a perspective view and a sectional side elevation respectively of front disk unit 18. FIGURES 16A & 16B illustrate perspective views from opposite angles of rotation of a rear disk unit 20.

FIGURES 17A & 17B illustrate a perspective view and a sectional side elevation respectively of a thrust transfer unit 460. FIGURE 18 is an exploded perspective view of thrust roller unit 463, which is incorporated in the thrust transfer unit 460 of Figures 17A, 17B.

FIGURE 19 is an exploded perspective view of bevel gear unit 464, which is incorporated in the thrust transfer unit 460 of Figures 17A, 17B.

FIGURE 20 is a perspective view of a thrust roller structure 468, which is incorporated in the thrust transfer unit 460 of Figures 17A, 17B.

FIGURES 21 A & 21 B illustrate exploded perspective views from two angles of rotation of a clamp unit 462, which is incorporated in the disk coupling unit 22.

FIGURES 22A & 22B illustrate a perspective view and a sectional side elevation respectively of the assembled clamp unit 462 of Figures 21 A, 21 B. FIGURES 23A & 23B illustrate perspective views from two angles of rotation of a three-mode synchronous embodiment of the invention

FIGURE 24 is a sectional side elevation of a three-mode unit 2001.

FIGURE 25A is perspective view of second mode shaft 2015. FIGURE 25B is a perspective view of a high unit 2021 .

FIGURE 25C is a perspective view of a direct unit 2017. FIGURE 25D is a perspective view of a low unit 2019. FIGURE 25E is a perspective view of a selector 2023. FIGURE 26 is a perspective view of a front casing 12. FIGURE 27 is a perspective view of a rear casing 14.

FIGURES 28A - 28C illustrate the selector 2023 position in the direct mode (Fig.

28A), low mode (Fig. 28B), and high mode (Fig. 28C) of the synchronous three-mode operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

CVT system 10 of the invention

Figures 1A, 1 B, 2 and 3 illustrate the CVT system 10 of the invention. The system 10 includes a front casing 12, rear casing 14, a variator unit 16, a front disk unit 18 (Figures

2 & 3), a rear disk unit 20 (Figures 2 & 3), a disk coupling unit 22, and a servo drive 24. These components and units are discussed in further details below.

1. VARIATOR UNIT 16 Referring to Figures 4A and 4B, the variator unit 16 includes a front spiral 26, a rear spiral 28, three follower units 30, a structure unit 32, a sump 34 and a bearing cap 36. The bearing cap 36 comprises a planar rectangular body 38 with a blind hole 40 extending through the centre of the body 38. The hole 40 is bordered at one side of the body 38 by a hollow cylinder 42 which is raised from the body 38. Four substantially evenly spaced holes 44 extend through the body 38 which are configured to received four bolts 46 therethrough.

The sump 34 comprises a hollow triangular body 48 including a base wall 48.1 , an end wall 48.2, and two opposing side walls 48.3 which are each connected at one side thereof to the end wall 48.2. Eight bolt-receiving holes 50 are provided in the side walls 48.3 of the triangular body 48 for accommodating eight bolts 52 of different lengths.

Recessed holes 54 in the end wall 48.2 accommodate the bolt heads.

1 .1 Structure unit 32

The structure unit 32, as can most clearly be seen in Figures 5A and 5B, includes a structure body 56, a structure center 58, three radial shaft units 60A - 60C, a gear coupling unit 62, a ratio drive unit 64, an oil pump 66, and pump support 68.

1.1.1 Structure center 58

The structure center 58, as can most clearly be seen in Figures 6A to 6D, includes a hollow cylindrical body 70 with a bore 71 extending through the body 70. The structure center 58 further includes three evenly spaced rib formations 72 connected to and extending radially outwardly from the cylindrical body 70, with each rib formation 72 defining a rib front face 72.1 , a rib rear face 72.2, and two opposing rib side faces 72.3. Each rib formation 72 includes a clearance cavity 73 extending through the rib formations 72.

At its radial free ends, each rib formation 72 terminates in a web foot 74. The web foot 74 comprises a web foot front face 74.1 , a web foot rear face 74.2, two web foot side faces 74.3, and a web foot end face 74.4. The web foot front face 74.1 is orientated substantially parallel to the rib front face 72.1 , but slightly offset therefrom such that a rib end step 72.4 is defined between rib front face 72.1 and the web foot front face 74.1. The web foot rear face 74.2 is arranged flush with the rib rear face 72.2. The two web foot side faces 74.3 are oppositely angularly disposed relative to the rib formations 72 so as to create a wide, radially curved web foot end face 74.4 between the web foot side faces 74.3. The web foot end face 74.4 is concentric with the cylindrical body 70. Threaded holes 76 extend through the web foot 74 between the web foot front and rear faces 74.1 ; 74.2.

The structure center 58 further includes three evenly spaced stud formations 78, connected to and extending radially outwardly from the cylindrical body 70 and alternately spaced intermediate the rib formations 72. Each stud formation 78 includes a raised step 80 where it is connected to the cylindrical body 70, a larger diameter stud 82 mounted to the raised step 80, and stepping down to a smaller diameter stud 84. A stud bore 86 extends through the stud formation 78 into the bore 71 of the cylindrical body 70. The cylindrical body 70 terminates at each end in an internal O-ring groove 88. Oil bores 90, 92 (Figure 6C) extend radially from the centre bore 71 of the cylindrical body 70, protruding through the rib formations 72 and the web feet 74 and terminating in oil holes 94 in the web feet end faces 74.4. Oil bores 90 are slightly larger in diameter than oil bore 92, and they terminate in collection cavities 96 in the web feet 74. Three sets of three radially evenly spaced small oil holes 98, 100 and 102 (Figure 6D) extend radially through cylindrical body 70. On its outer surface, cylindrical body 70 includes at one end thereof a C-clip groove 104 and step 106, creating bearing surface 108; and on the other end thereof includes C-clip groove 110 and step 112, creating bearing surface 114 terminating in face 116.

1.1.2 Radial shaft units 60A - 60C

Radial shaft units 60A - 60C, as can most clearly be seen in Figures 7A - 7C, each includes an elongate radial shaft 120. On its outer surface radial shaft 120 includes four elongate, circumferentially evenly-spaced grooves 136 extending substantially the length of the shaft 120. The shaft 120 terminates at a first end thereof in a radially inward step 138, which creates step surface 140. The shaft terminates at a second end thereof in a radially outward step 144 and a bevel gear 146. A larger diameter bore 148, which steps down to a smaller diameter bore 150, both of which are coaxial with the shaft 120, passes through the bevel gear 146.

At the first end of the shaft 120, shaft unit 60 further includes, in sequential order, a deep groove ball bearing 128, a spacer 130, a washer 132 and a bolt 134. At the second end of the shaft 120, the shaft unit 60 includes two cylindrical roller bearings 122, 124 with a washer 126 located intermediate bearings 122, 124.

The shaft unit 60 is assembled at the first end of the shaft 120 by locating step surface 140 within deep groove ball bearing 128, concentrically assembling spacer 130 and washer 132, and securing the assembly with bolt 134, such that a threaded blind hole 142 is defined between the bolt 134 and the shaft 120. The shaft unit 60 is assembled at the second end of the shaft 120 by locating roller bearing 122 within smaller diameter bore 150, and locating roller bearing 124 in larger dimeter bore 148, with washer 126 sandwiched between bearings 122, 124.

The variator unit 16 includes three radial shaft units 60A - 60C. Referring to Figures 5A and 5B, radial shaft units 60A and 60B differ slightly in that spacer 130 in shaft unit 60A is replaced in shaft unit 60B with a spur gear 152. Moreover, in radial shaft unit 60C, shaft 120 is extended at the first end thereof to locate within a slidable input sleeve 154. An inner surface of input sleeve 154 includes a number of radially inwardly disposed ribs (not shown) which are complimentarily configured to the grooves 136 of shaft 120, thus enabling the input sleeve 154 to engage with and drive shaft 120. An exterior surface of input sleeve 154 is stepped, creating sealing surface 156, which engages an oil seal 158 located on c-clip 160. A top end of input sleeve 154 includes a recess 162 against which washer 132 acts. 1.1.3 Gear coupling unit 62

The gear coupling unit 62, which is best illustrated in Figures 8A - 8C, includes a bevel gear 164, two oppositely facing taper roller bearings 166, an end cap 168, and four counter sunk bolts 170.

The bevel gear 164 comprises a hollow cylindrical body 172 which defines a centre bore 174. The centre bore 174 is stepped to accommodate taper roller bearings 166. The cylindrical body 172 terminates at one thereof in a series of bevel gear teeth 176, and at the opposite end thereof in a rim 178, to which the end cap 168 is connected. Threaded holes 180 extend through the cylindrical body 172 approximate the rim 178.

The end cap 168 comprises washer 182 with four evenly-spaced countersunk holes

184. In the assembled gear coupling unit 62, end cap 168 is located against rim 178 via countersunk bolts 170 located in holes 184 concentric with threaded holes 180 to locate opposite facing taper roller bearings 166 against each other.

1.1.4 Ratio drive unit 64 The ratio drive unit 64, as can most clearly be seen in Figures 9A and 9B, includes a first shaft arrangement 186 and second shaft arrangement 188. First shaft arrangement 186 includes a ratio shaft 190 and two deep groove ball bearings 194, 196 arranged approximate opposite ends of the ratio shaft 190. At a first end, the ratio shaft 190 includes a c-clip groove (not shown) for locating a c-clip 192. At a second end, the ratio shaft 190 carries three spaced apart spur gears 198, 200 and 202. Deep groove ball bearing 194 is located against c-clip 192, while deep groove ball bearing 196 is located against spur gear 198.

The second shaft arrangement 188 includes a transfer shaft 204, and two deep groove ball bearings 206, 208 arranged approximate opposite ends of the transfer shaft 204. At a first end, the transfer shaft 204 carries a spur gear 210, and includes a key way 220 and c-clip groove (not shown). At a second end, the transfer shaft 204 includes a radially inwardly stepped shaft 222, which is bordered by a radially outwardly stepped rim 224. The transfer shaft 204 terminates in a stud 228. Four circumferentially evenly spaced axial threaded holes 226 extend through the stepped rim 224.

The second shaft arrangement 188 also includes an adjuster spur gear 212 and four bolts 214. Adjuster spur gear 212 includes four evenly spaced circumferential slotted holes 216 with a center bore 218. In the assembled second shaft arrangement 188, spur gear 210 is driven via a key (not shown) located in key way 220. Deep groove ball bearing 208 is located against stepped shaft 222, while bore 218 of adjuster spur gear 212 is located over stud 228 of the transfer shaft 204. Bolts 214 locate spur gear 212 against rim 224 via slotted holes 216 and threaded holes 226. Through slotted holes 216, spur gear 212 can rotatably be adjusted relative to transfer shaft 204.

Spur gears 198 and 210 have the same number of teeth and spur gears 200 and 212 have the same number of teeth and are meshed.

1.1.5 Structure body 56

The structure body 56, as can most clearly be seen in Figures 10A and 10B, includes a rim 230, which comprises a substantially circular-like interior rim face 231 , an exterior rim face 232, a front rim face 233, and a rear rim face 234. The structure body 56 includes six rib formations 236 that extend partially inwardly from the interior rim face 231 of the structure body 56 towards a central axis W, with each rib formation 236 including a front rib face 237, a rear rib face 238, a first side face 239, and second side face 240. The rib formations 236 are divided into three sets of two rib formations 236 each, with the two rib formations 236 in each set being angularly disposed relative to each other such that they join each other at an apex 242 to form a substantially triangular configuration with the rim 230 of the body 56. Rib formations 236 of neighbouring rib sets are configured substantially parallel to each other. The structure body 56 includes three identical cut-out formations 244, radially spaced evenly at 120 degrees apart, with each cut-out formation 244 extending from the central axis W and terminating at interior rim face 231 A of the rim 230 in a bearing pocket 246. Each cut-out formation 244 is bordered at either side thereof by two parallel rib formations 236 of neighbouring rib sets.

Each set of rib formations 236 includes a semi-circular step 248 defined in the front rib faces 237 of adjoining rib formations 236 approximate the apex 242 of the rib formations set, with the semi-circular step 248 being concentric with the central axis W. The semi circular step 248 creates a rib formation flange 250 in the rear rib faces 238 of adjoining rib formations 236, which forms the apex 242 of each rib formations set. Two countersunk holes 252 extend through each rib formation flange 250.

The rim 230 includes a first planar exterior rim face 232.1 which is substantially tangentially orientated relative to the circular-like interior rim face 231 and which is orientated perpendicularly to the first side faces 239 of the rib formations 236 which connect to first planar exterior rim face 232.1 . The first planar exterior rim face 232.1 is bordered at one side thereof by a servo flange 254 extending away from the rim 230. Two axial bearing pockets 256, 258 extend from rib face 237 into the rim 230 between the first planar exterior rim face 232.1 and the servo flange 254, with a bore 260 and four evenly-spaced holes 262 extending through the servo flange 254. Rear rib face 238 includes identical bearing pockets 256 and 258 concentric with the respective pockets on face 237, while the concentric pockets are connected by a smaller diameter bore. Both bearing pockets 256 and 258 have the same radial distance with respect to the center axis W of rim 230. A C-clip groove 264 is defined within first planar exterior rim face 232.1 . The rim 230 includes a second planar exterior rim face 232.2 which is substantially tangentially orientated relative to the circular-like interior rim face 231 , and which is circumferentially spaced from the first planar exterior rim face 232.1 . The second planar exterior rim face 232.2 is perpendicularly orientated relative to the first side faces 239 of the rib formations 236 which connect to the second planar exterior rim face 232.2. The second planar exterior rim face 232.2 includes two symmetrical pump cavities 266 and 268, two blind bearing pockets 270 and 272, and a bearing pocket 274. Blind bearing pockets 270, 272 and pump cavities 266, 268 are symmetrically positioned around a plane Y, parallel to faces 239, while pane Y is also the axis of bearing pocket 274.

The two symmetrical pump cavities 266 and 268, as can most clearly be seen in Figure 11 , are each rectangular cavities. A groove 278 extends from each of the pump cavities 266, 268 through a rib formation 236 and terminating in an opening within semi-circular step 248. The second side face 240 of the rib formation 236 which runs parallel to groove 278 includes angled threaded holes 280.

The structure body 56 includes a first sump cut-out 282, a second sump cut-out 284, and third cut-out 286, with each of these cut-outs being defined between two angularly disposed and adjoining rib formations 236 and the interior rib face 231 . The rim 230 is suitable shaped around sump cut-outs 282 and 284 to act as a sump, which will be explained later. 1.1.6 Pump support 68

The pump support 68 as can most clearly be seen in Figure 5C, comprises a rectangular body 288 with a front face 288.1 and a rear face 288.2. The rear face 288.2 includes a raised step 290 extending part of the length of the rectangular body 288. Two blind bearing pockets 292, 294 and a hole 296 are arranged in line along the length of the rectangular body 288, extending through the body 288. Each of the blind bearing pockets 292, 294 and the hole 296 are bordered by a semi-circular cut-out 298 stepping down from the front face 288.1 . Six holes 300 extend through the rectangular body 288. 1.1.7 Oil pump 66

Oil pump 66, which is best illustrated in Figure 12, includes a gear pump 302, featuring a standard gear pump with integrated valve body to allow the oil pump 66 to always take in oil through oil intake 304, and pump oil out through holes 306, irrespective of the direction of rotation of pump input drive gear 308. The oil pump 66 can be located in either pump cavity 266 or 268 to allow input sleeve 154 (refer Figure 7C) to be in either a horizontal or vertical position, while oil intake 304 takes in oil either from first sump 282 or second sump 284 respectively. The oil pump 66 is located with its pump case 310 flush with face 240 of the rib formation 236 (refer Figure 10A), with bolts 312 located in threaded holes 280 of the rib formation 236. Oil exits holes 306 and flows into groove 278 extending through the rib formation 236, and out through the opening at the semi-circular step 248. The pump input drive gear 308 is driven by gear spur 152 via an idler gear 314 (Figure 5D). 1.1.8 Assembled structure unit 32

In the assembled structure unit 32, as presented in Figures 5A and 5B, structure center 58 is located inside structure body 56 by locating web feet 74 against semi-circular steps 248 such that web foot front faces 74.1 abut rib formation flanges 250, while web foot side faces 74.3 are parallel and flush with the first side faces 239 of the rib formations 236. The structure center 58 is secured via countersunk bolts 316 (Figure 5A) through countersunk holes 252 (Figure 10A) and threaded holes 76 (Figure 6B).

In the assembled structure unit 32 (Figures 5A, 5B), the radial shaft units 60 are rotatably located in structure body 56 through location of the deep groove ball bearing 128 (Figure 7A) in bearing pocket 246 (Figure 10A), while studs 82 and 84 of structure center 58 (Figure 6A) are located within the internal bore of cylindrical roller bearings 124 and 122 of radial shaft 60 (Figure 7A). An external face of deep groove ball bearing 128 of radial shaft unit 60B is flush with face 232.2 of structure body 56, while an external face of deep groove ball bearing 128 of radial shaft unit 60A is flush with an exterior rim face 232.3 of rim 230. An external face of deep groove ball bearing 128 of radial shaft unit 60C is located against a C-clip in C-clip groove 264. The other sides of deep groove ball bearings 128 bear against steps 246.1. In the assembled structure unit 32, gear coupling unit 62 is rotatably located on structure centre 58 by inserting cylindrical body 70 through centre bore 174 of gear coupling unit 62, such that taper roller bearings 166 of gear coupling unit 62 bear against an external surface of cylindrical body 70. The gear coupling unit 62 engages cylindrical body 70 such that it is trapped between step 112 (Figure 6D) on one end, and a C-clip located in C-clip groove 110 at the opposite end. Bevel gear teeth 176 of gear coupling unit 62 mesh with all three bevel gears 146 of the respective radial shaft units 60. Ratio drive unit 64 is rotatably located inside structure body 56 via the location of deep groove ball bearing 206 in bearing pocket 256, bearing 194 in bearing pocket 258, bearing 208 in opposite bearing pocket 258, and bearing 196 in opposite bearing pocket 256.

As described above, the oil pump 66 pumps oil into groove 278 of structure body 56 (Figure 11 ), from where it flows into collector cavity 96 of web foot 74 (Figures 6A, 6B), and though oil holes 90 into bore 71 of cylindrical body 70 (Figure 6C), from where it is distributed to all oil holes terminating in bore 71 to provide oil to all parts of the CVT system. Not all oil holes and passages are named or shown, but the CVT system may include all such oil holes and passages to provide oil to all needed parts.

1 .2 Follower unit 30

Follower unit 30, as is best illustrated in Figures 13A - 13D, comprises a substantially rectangular follower body 318 having a top face 320, a bottom face 322, a front face 324, a rear face 326, and two opposing side faces 328 extending between the front and rear faces 324, 326. The top face 320 transitions into the front face 324 through a first chamfer 330, while the top face 320 transitions into the rear face 326 through a second chamfer 332. Similarly, the bottom face 322 transitions into the front face 324 through a third chamfer 334, while the bottom face 322 transitions into the rear face 326 through a fourth chamfer 336. A central bore 338 extends through the rectangular body 318 between the top and bottom faces 320, 322. The top face 320 includes a circular raised step 340 which circumferentially borders the central bore 338. Two parallel cam followers 342 extend from each side face 328 of the rectangular body 318, with a raised, rectangular step 344 extending from each of the side faces 328 intermediate the two cam followers 342. The raised step 344 transitions onto the side face 328 through fifth chamfers 346. The side faces 328 each include a top blind threaded hole 358, and a bottom blind threaded hole 360, located on either side of the rectangular step 344. The freely-rotatable cam followers 342 are typically of a standard cam follower bearing type with SKF bearing part number KRV 26 PP (for example). They are connected to the follower body 318 by screwing their standard threaded shafts 394 into holes 358 and 360. The bottom face comprises a first bottom face 322.1 , which steps down inwardly to a second bottom face 322.2, with a semi-circular step formation 348 extending perpendicularly between the first and second bottom faces 322.1 , 322.2, concentric with the central bore 338. The follower body 318 further includes a center bore bearing pocket 350 extending into the follower body 318 from the second bottom face 322.2, including an internal C-clip groove 352 inside the bearing pocket 350. An internal step 354 and sixth chamfer 356 (Figure 13D) links the bearing pocket 350 to the second bottom face 322.2. Follower body 318 is symmetrical around a plane of section E-E, except for blind holes 358 and 360, which are at swapped-around positions on the side faces 328.

The follower unit 30 further includes a driver 362 which is rotatably locatable within follower body 318. Driver 362 is a circular body comprising a hollow shaft 364 which, at its exterior surface, expands at its lower end into a perpendicular, circumferential first face 366. The first face 366 steps down through a circumferential and outwardly coned first step 368 to a circular second step 370 of increased diameter. The second step 370 in turn circumferentially steps down to a driver rim 372 of increased diameter. The driver rim 372 has a lower face 374 which includes a radially inwardly disposed circular step 376. At an opposite end from the first face 366, the hollow shaft 364 includes an external C-clip groove 378, which circumferentially borders an upper end 365 of the shaft 364. The hollow shaft 364, at its interior surface, includes a splined bore 380 extending from the upper end 365 of the shaft 364 into the driver 362. The splined bore 380 expands into a central bore 382 of increased diameter, creating bore face 384 which transitions into bore face 386 through seventh chamfer 388. In the assembled follower unit 30, two deep groove ball bearings 390 are sandwiched together in bearing pocket 350 between step 354 and C-clip 392, which is located in C- clip groove 352. The internal diameters of bearings 390 are located between face 366 and c-clip 392.1 , located in groove 378. The driver 362 is rotatably located within follower body 318 by inserting shaft 364 into the central bore 338 of the follower body 318, such that the deep groove ball bearings 390 are radially trapped between the shaft 364 and the bearing pocket 350, and axially trapped between the C-clip 392 and the face 366, with lower face 374 of driver 362 being flush with first bottom face 322.1 of follower body 318.

1 .3 Front spiral 26

The front spiral 26, as can most clearly be seen in Figure 14, is a circular disk body with an outer rim 396, a front face 398, a rear face 400, and centre bore 402 extending through the disk body. The rim 396 includes a section of spur gear teeth 404. A circumferential chamfer 406 through the centre bore 402 links the front and rear faces 398, 400. Front face 398 includes three evenly spaced cut-outs 408, each cut-out 408 creating an up-cam 410 and a down-cam 412, while the rest of the cut-outs 408 are for clearance purposes for parts and are not further discussed.

Rear spiral 28 is identical to front spiral 26 except that the section of spur gear teeth 404 are at a different location on the rim 396, which will be discussed later.

1 .4 Assembled variator unit 16 In the assembled variator unit 16 (see Figure 4), front spiral 26 is rotatably located in structure body 56 with front face 398 of spiral 26 abutting a first side of rib formations 236 of the structure body 56, while gear teeth 404 of spiral 26 mesh with and engage spur gear 210 of ratio drive unit 64 (Figure 9A). Rear spiral 28 is rotatably located in structure body 56 with front face 398 of spiral 28 abutting opposite sides of rib formations 236, while gear teeth 404 mesh with and engage spur gear 198 of ratio drive unit 64. Chamfer 406 of spiral 26 provides clearance for bevel gears 146 of radial shaft units 60 (Figure 7).

The three follower units 30 are each located in cut-out formations 244 of structure body 56 via radially slidable engagement of splined bore 380 of driver 362 with the complimentarily shaped grooves 136 on radial shaft 120 in order for the radial shaft unit 60 to drive driver 362. The radial position of the follower units 30 is regulated by engagement of the cam followers 342 extending from follower bodies 318 within the cut outs 408 of spiral 26, with an up-cam 410 and a down-cam 412. Rotation of the front spiral 26 and rear spiral 28 in opposite directions, via the ratio drive unit 64, causes a radial adjustment of the follower units 30 and thus changes the ratio. Engagement of the follower bodies 318 with both the up-cam 410 and the down-cam 412 allows for positioning of the follower units 30 radially towards and away from an axis extending through bore 402 of spirals 26, 28. Bearing cap 36 is connected to exterior rim face 232.3 of structure body 56 and axially locates on the side of deep groove ball bearing 128 of radial shaft unit 60A, while sump 36 is connected to second planer exterior rim face 232.2 of structure body 56. The pump support 68 axially locatesdeep groove ball bearing 128 of radial shaft unit 60B on one side. 2. FRONT DISK UNIT 18

Front disk unit 18, as can most clearly be seen in Figures 15A and 15B, comprises an elongate output shaft 414 and an integrally formed circular disk 416 extending radially spaced about the output shaft 414, such that an open-ended radial bore 418 is defined between the output shaft 414 and the disk 416. The radial bore 418 steps down to an internal bearing pocket 420 of decreased diameter.

The disk 416 includes a peripheral disk rim 422 and a planar disk drive face 424. The disk 416 is connected to and transitions into the output shaft 414 through an external hollow hub 426 and an external step 428.

The output shaft 414 varies in diameter along its length, with a stepped-up shaft section 414.1 and 414.6 of increased diameter extending between a first end 430 of the output shaft 414 and the external step 428, after which the shaft diameter decreases to a stepped-down shaft section 414.2 where the output shaft 414 extends through the radial bore 418. The stepped down shaft section 414.2 terminates, in sequential order, in a stepped shaft section 414.3 of slightly increased diameter, followed by a splined shaft section 414.4, and terminating in a threaded shaft end section 414.5. A radial oil hole 432 extends through stepped-down shaft section 414.2 where it flows into axial oil channel 434 which terminates in an open oil hole 436 in a second end 438 of output shaft 414. The front disk unit 18 includes deep groove ball bearings 440 and 442 with bearing 440 located against external step 428 and bearing 442 located in internal bearing pocket 420. In the assembled CVT system 10 of the invention, bearing 442 of front disk unit 18 is axially slidably located on one side of cylindrical body 70 (Figures 6A, 6B), while disk drive face 424 is in traction drive line contact with the rims 372 of drivers 362 of follower units 30. 3. REAR DISK UNIT 20

Rear disk unit 20, which is best illustrated in Figures 16A and 16B, comprises a circular rear disk 444 having a planar front drive face 446, a rear face 448, and a central bore 450 extending axially through the disk 444. The central bore 450 includes an internal C- clip 452, which is located in an internal C-clip groove (not shown).

The rear disk unit 20 includes a needle bearing 454 located in central bore 450 and maintained in place through C-clip 452 on one side, and step 450.1 on the other side. A bevel gear 456 is seated against rear face 448 such that it circumferentially borders needle bearing 454. In between face 448 and bevel gear 456 a flat face 458 is defined.

In the assembled CVT system 10 of the inventionO, needle bearing 454 of rear disk unit 20 is axially slidably located on cylindrical body 70 of structure centre 58 (Figures 6A, 6B) on an opposite side of cylindrical body 70, while front drive face 446 of the rear disk unit 20 is in traction drive line contact with the rims 372 of drivers 362 of follower units

30.

4. DISK COUPLING UNIT 22 Referring to Figure 2, disk coupling unit 22 includes a thrust transfer unit 460 and a clamp unit 462, which are discussed in further details below.

4.1 Thrust transfer unit 460

Thrust transfer unit 460, which is illustrated in Figures 17A and 17B, includes three evenly-spaced thrust roller units 463 (also illustrated in Figure 18), two bevel gear units 464, which are arranged 180 degrees apart (also illustrated in Figure 19), and a thrust roller structure 468 (also illustrated in Figure 20).

4.1.1 The thrust roller unit 463 (Figure 18) The thrust roller unit 463 comprises a roller cap 470, a circular rolling disk 472, and two deep groove ball bearings 474, 476 which are arranged on either side of the disk 472.

The roller cap 470 is a substantially rectangular body having a front face 478, a rear face 480, and two opposing side faces 482. A rectangular step 484 extends outwardly from each of the side faces 482, while two parallel rectangular extrusions 486 protrude from the rear face 480. Front face 478 includes a circular cut-out 488 which steps down to a blind bearing pocket 490 of decreased diameter. Four parallel holes 492 extend through the roller cap 470 approximate four corners of the rectangular body, terminating in the rear face 480 in recesses 492.1

The circular disk 472 terminates in a peripheral rim 472.1 . A stepped shaft 494 extends axially through disk 472, with a bore 496 extending through stepped shaft 494.

During assembly of the thrust roller unit 463, deep groove ball bearing 474 is located in bearing pocket 490. Disk 472 is connected to deep groove ball bearing 474 through one end of shaft 494, while deep groove ball bearing 476 engages an opposite end of shaft 494. Four bolts 498 extend through the holes 492, such that their bolt heads are nestled in recesses 492.1. The disk 472 is thus rotatably and axially located in roller cap 470.

4.1.2 The bevel gear unit 464 (Figure 19) The bevel gear unit 464 comprises, in sequential order, a bearing pin 500, a washer 502, a first taper roller bearing 504, a bevel gear 506, and second taper roller bearing

508.

The bearing pin 500 comprises an elongate shaft 510 of varying diameter, dividing the shaft 510 into three sections. A first shaft section 510.1 , having the largest diameter, steps down to a second shaft section 510.2 of decreased diameter, which steps down further to a third shaft section 510.3 of the smallest diameter. The bearing pin 500 includes a recess 511 and a bore 512 extends axially through the bearing pin 500. A radial oil hole 513 extends through shaft section 510.2 into bore 512.

The bevel gear 506 includes a top bearing pocket 514 of larger diameter, which steps down to a co-axial bottom bearing pocket 516 of smaller diameter, with an intermittent step 518 being arranged intermediate the top and bottom bearing pockets 514, 516.

During assembly of the bevel gear unit 464, washer 502 is positioned over the bearing pin 500 such that it is located on shaft section 510.2, pressing against shaft section 510.1 . First taper roller bearing 504 is inserted into top bearing pocket 514 and located on shaft section 510.2, pressing against washer 502. Shaft section 510.3 protrudes into bottom bearing pocket 516 such that second taper roller bearing 508 is located in bottom bearing pocket 516 and on shaft section 510.3, thereby rotatably assembling the bevel gear 506 on bearing pin 500.

4.1.3 Thrust roller structure 468 (Figure 20)

Thrust roller structure 468 comprises a substantially circular rim 518, which includes an exterior rim face 520, an interior rim face 522, and two opposing side faces 524. Three peripherally interrupted and evenly-spaced rim extensions 526.1 , 526.2 and 526.3 extend radially outwardly from the exterior rim face 520. Each rim extension 526.1 -

526.3 includes a substantially rectangular, planar extension face 528, which is tangentially orientated relative to rim 518, and which steps down onto exterior rim face 520. Four threaded holes 530 extend through each rim extension 526 approximate its four corners.

Bearing pockets 532 are located in rim extension 526.1 , 526.2 and 526.3 with bearing pocket 532 in rim extension 526.1 stepping down into a smaller diameter hole 534. An open-ended hole 542 protrudes through rim 518 at a position which is directly radially opposite from bearing pocket 532 and hole 534 such that an axis X would intersect bearing pocket 532 and holes 534 and 542. Hole 542 includes a C-clip groove 544. Hole 534 and hole 542 have the same internal diameters.

The thrust roller structure 468 further includes a central hub 536 with four spokes 538.1 - 538.4 extending radially outwardly from the hub 536 and connecting to interior rim face 522. The hub 536 is a hollow cylindrical body with a central bore 540 extending through the hub 536. The hub 536 includes two radially opposite, planer hub faces 546.1 and 546.2, with hub face 546.1 facing bearing pocket 532 and hole 534, and with hub face 546.2 facing hole 542. A hub hole 548 protrudes through each of the hub faces 546.1 , 546.2 aligned with and on the same axis X that intersects bearing pocket 532, and holes 534 and 542. The hub 536 is positioned within the rim 520 such that a first cut-out 550 is defined between rim extension 526.1 , hub face 546.1 and neighbouring spokes 538.1 and 538.2. In addition, a second, radially opposite cut-out 552 is defined between rim 520, hub face 546.2, and neighbouring spokes 538.3 and 538.4. Other cut-outs are introduced simply for mass reduction outcomes and do not warrant further discussion. An elongate passage 554 (also refer Figure 17B) extends through rim extension 526.2, through spoke 538.3 and into central bore 540. A similar elongate passage 554 extends through rim extension 526.3, through spoke 538.4 and into central bore 540.

4.1.4 Assembled thrust transfer unit 460

In the assembled thrust transfer unit 460, the three thrust roller units 463 are mounted to the rib extensions 526.1 - 526.3 such that face 478 of roller cap 470 is seated atop extension face 528, with bolts 498 protruding through holes 492 and threaded holes 530 to secure the thrust roller units 463 to the thrust roller structure 468. Deep groove ball bearings 476 are located in bearing pockets 532 of thrust roller structure 468.

A first bevel gear unit 464 is located in thrust roller structure 468 by inserting third shaft section 510.3 of bearing pin 500 into hub hole 548 such that second taper roller bearing 508 is flush with hub face 546.1 , while first shaft section 510.1 of bearing pin 500 is located in hole 534 with washer 502 flush with interior rim face 522.1. A second bevel gear unit 464 is located in thrust roller structure 468, radially opposite from the first bevel gear unit, by inserting third shaft section 510.3 of bearing pin 500 into hub hole 548 such that the second taper roller bearing 508 is flush with hub face 546.2, while first shaft section 510.1 of bearing pin 500 is located in hole 542 with washer 502 flush with interior rim face 522.2. The bearing pin 500 which is located in hole 542 includes a C- clip 558, located in C-clip groove 544, to secure the bearing pin 500 in place. A grub screw 560 plugs the hole 512 on one side. 4.2 Clamp unit 462

Variable clamping embodiment: In an ideal CVT system 10 of the invention, the clamping force created by disk spring 572 (refer Figure 3) needs to be variable in proportion to the input torque applied at input sleeve 154 of radial shaft unit 60 to always ensure just enough force in the traction drive patches between the rim 372 of driver 362, disk drive face 424 of front disk unit 18, and front drive face 446 of rear disk unit 20, to prevent excessive slip. Too much clamping force results in unnecessary losses. For an ideal clamping, a system is required that uses as input, the input torque at input sleeve 154 and then creates a proportional clamping force. Such a system would be complicated and possibly need some hydraulic or electric control. Another method would be to use the output torque at the respective disks and together with the current ratio to calculate the input torque and thereafter the proportional clamping force. Such a system would also be complicated and possibly need some hydraulic or electric control. As a compromise, the variable clamping embodiment of the clamp unit 462 below presents a very simple self-regulating variable clamping system, which utilises as it only input the torque of the rear disk unit 20. By only using the torque on the rear disk unit 20 to regulate clamping force, the current ratio is an unknown to this system. The result is that ideal clamping force will only be achieved in the close to 1 :1 ratio (when driver 362 is at its smallest radius) while in other ratios over-clamping will be the result in partial load scenarios. Flowever, this over-clamping is much less than it would have been without the above variable clamping. The system below also includes means to limit the clamping force to a maximum, irrespective of the input or disk torque, and further facilitates clamping optimization.

Clamp unit 462, which is best illustrated in Figures 21 A, 21 B and 22A, 22B, comprises, in order of sequence, a needle bearing 564, a clamp hub 568, a clamp bush 570, a disk spring 572 (Belleville spring), a load cam unit 574, deep groove ball bearing 576, and a nut 578.

4.2.1 Clamp hub 568 The clamp hub 568 is a circular disk body having a front face 580, a rear face 582, and a peripheral rim 584 which is raised and axially protrudes from both the front and rear faces 580, 582. The front face 580 includes an axially mounted bevel gear 586 with a bearing pocket 588. The bearing pocket 588 steps down through step 590 to a smaller diameter bore 592 (Figure 22B).

The rear face 582 includes a circular, axially positioned step formation 594 of smaller diameter than the rear face 582, with a hollow boss 596 connected to and extending axially from the step formation 594 and defining a boss bore 598. Three evenly-spaced fingers 600 extend radially outwardly from the boss 596 and terminate at the periphery of the step formation 594.

Clamp bush 570 is a hollow cylindrical body with a centre bore. 4.2.2 The load cam unit 574

The load cam unit 574 includes a first cam 602, a second cam 604, and a roller holder 606 with three cylindrical cam rollers 608, positioned intermediate and sandwiched between the first and second cams 602, 604.

The first cam 602 includes a cylindrical disk 610 having a front face 612 and a rear face 614. A hollow bush 616 extends axially from the rear face 614, for locating deep groove ball bearing 576. A hollow boss 618 of smaller diameter, but co-axial with hollow bush 616, extends from the front face 612, bush 618 defining a splined bore 620. The first cam 602 also includes a cam arrangement on its front face 612, the cam arrangement comprising three evenly-spaced sets of oppositely-sloped cam surfaces 622.1 , 622.2, with each set of cam surfaces 622.1 , 622.2 being separated by a stop formation 622.3.

The second cam 604 includes a circular disk 624 having a front face 626 and a rear face 628, with a bore 630 penetrating through the disk 624. The front face 626 carries a cam arrangement which is identical to the cam arrangement of the first cam 602. The second face 628 includes three evenly-spaced cut-out formations 632 which extend radially outwardly from the bore 630, and which are complimentarily configured to engage and mate with the clamp hub 568 by accommodating hollow bush 596 in bore 630, and fingers 600 in cut-outs 632 so that drive can be transmitted between hub 568 and second cam 604, while second cam 604 is axially slidably engaged with hub 568 in the assembled clamp unit 462. Roller holder 606 is a circular body having a front face 634, a rear face 636, and a raised peripheral rim 638 with a central bore 640 extending through the body. Three evenly-spaced cut-outs 642 extend radially outwardly from the central bore 640 to the peripheral rim 638 to accommodate the three cam rollers 608. It will be appreciated that the axes of rotation of the three cam rollers 608 in roller holder 606 are perpendicular to the axis of rotation of clamp hub 568.

4.2.3 Assembled load cam unit 574

In the assembled load cam unit 574, roller holder 606 is sandwiched between the first cam 602 and the second cam 604, with cylindrical cam rollers 608 positioned in line contact with cam surfaces 622.1 or 622.2 of both the first and second cams 602, 604. The cam surface 622.1 is characterised by an axial lead, denoted by LC in the equation below, with unit of mm/rev, that will displace cylindrical cam rollers 608, in line contact with it, in an axial direction away from front face 612 when first cam 602 is rotated in the direction of arrow 644 relative to cylindrical cam rollers 608. The cam surface 622.2 is characterised by the same lead and effect on cylindrical cam rollers 608, but when first cam 602 is rotated in the direction opposite to arrow 644. Cam surfaces 622.1 or 622.2 each terminate in a circular fillet 622.5 with radius equal to the radius of cylindrical cam rollers 608 and acts as limiting stops for cylindrical cam rollers 608 as it rolls across cam surfaces 622.1 and 622.2 during operation of the load cam unit 574. Cam surfaces 622.1 and 622.2 are joined by a suitable fillet 622.4. Each cam surface 622.1 and 622.2 is also characterised by an angular rotation angle b, through which the first cam 602 and the second cam 604 can rotate, relative to cylindrical cam rollers 608, while the cylindrical cam rollers 608 rolls over the respective cam surface 622.1 and 622.2.

The effect of this is that upon relative rotation of first cam 602 relative to second cam 604 from a starting position, where the cam rollers 608 are positioned in fillets 622.4, first cam 602 and second cam 604 will be axially displaced relative to each other at a rate of 2 x LC x relative rotation angle (in degrees)/360, with maximum relative displacement equal to:

Lmax=2 x LC x b /360 mm - Equation 1 when the cam rollers 608 engage and stop against the circular fillets 622.5. This is valid irrespective of the direction of relative rotation between first cam 602 and second cam

604.

The effect of the above is that the disk spring (Belville spring) 572 can only be compressed through a maximum displacement of Lmax, after which cam rollers 608 engage and stop against the circular fillets 622.5. If the spring constant of the disk spring 572 is denoted as K, in units of N/mm, then a maximum clamping force of K ^* Lmax will be generated. Figure 22B presents the disk spring 572 in its uncompressed state, which indicates a compression space of CS. To function correctly CS needs to be larger than Lmax.

Note that rollers 608 may not necessarily be in line contact with cam surfaces 622.1 or 622.2, but may have any optimised shape and their axis may also not be perpendicular to axis Y. Rollers 608 may also be spherical and cam surfaces 622.1 or 622.2 may include suitable grooves.

Note that in either first cam 602 or second cam 604, cam surfaces 622.1 , 622.2, fillets 622.5, 622.4 and formation 622.3 may be eliminated and replaced with a flat face on which the rollers 608 can roll during operation and the lead LC on the unchanged cam can simply be increased to account for this change and the mathematical model adapted accordingly. 4.2.4 Assembled clamp unit 462

In the assembled clamp unit 462, disk spring 572 bears against rear face 582 of clamp hub 568, while its inner bore 571 bears against face 628. Needle bearing 564 is located in bearing pocket 588, while clamp bush 570 is located in center bore 598. Deep groove ball bearing 576 is located on hollow bush 616 such that it is seated against the step 614.1 on the rear face 614 of first cam 602, while nut 578 is located inside hollow bush 616 and against face 616.1 .

Assembled disk coupling unit 22

In the assembled disk coupling unit 22, as can most clearly be seen in Figure 2, clamp unit 462 is located concentrically with the thrust transfer unit 460, while the peripheral rim 472.1 of circular disk 472 of thrust roller unit 463 is in rolling line contact with peripheral rim 584 of clamp hub 568 while bevel gears 506 mesh with bevel gear 586. Assembled CVT system 10

Referring to Figure 3, in the assembled CVT system 10, the disk coupling unit 22 is concentrically located on cylindrical body 70 of structure centre 58, with clamp bush 570 being rotatably and axially slidably located on cylindrical body 70 of structure centre 58, and with splined bore 620 of load cam unit 574 axially slidable engaging splined shaft section 414.4 of front disk unit 18, and with nut 578 of clamp unit 462 engaging threaded shaft end section 414.5 of front disk unit 18. Rim 472.1 is in rolling line contact with face 458 of rear disk unit 20 while bevel gear 456 meshes with bevel gears 506.

5. FRONT CASING 12

Front casing 12, which is best illustrated in Figure 26, includes a connection plate 650, including a front face 652, which plate 650 is complimentarily profiled to be connected to one side of the structure body 56 of variator unit 16. Connected to the front face 652 is an interrupted, circular disk plate 654. A number of holes (not shown) penetrate through the plate 650, arranged predominantly peripherally about the disk plate 654, with bolts 656 penetrating through the holes. The front casing 12 further includes a central bearing pocket 658, to locate deep groove ball bearing 440 of front disk unit 18 (Figure 15B). Central bearing pocket 658 steps down to a smaller diameter hole 660, which in turn is sealed with an oil seal 662 which runs on shaft 414.6. A sump 664 is defined radially between the central bearing pocket 658 and a periphery of the connecting plate 650. The remainder of front casing 12 is suitable shaped to enclose the components of the CVT system 10. Front casing 12 is located in the CVT system 10 with plate 650 seated against rear rim face 234 of structure body 56, and while circular disk plate 654 abuts rear face 400 of front spiral 26, while bolts 656 engage suitable threaded holes on face 234.

6. REAR CASING 14

Rear casing 14, as can most clearly be seen in Figure 27, includes a connection plate 666, including a front face 668, which plate 666 is complimentarily profiled to be connected to an opposite side of the structure body 56 of variator unit 16. Connected to the front face 668 is an interrupted, circular disk plate 670. A number of holes (not shown) penetrate through the plate 666, arranged predominantly peripherally about the disk plate 670, with bolts 672 penetrating through the holes. The rear casing 14 further includes a central blind bearing pocket 674, to locate deep groove ball bearing 576 of clamp unit 462. A sump 676 is defined radially between the central bearing pocket 674 and a periphery of the connecting plate 666. Rear casing 14 includes three evenly- spaced extrusions 678 which locates intermediate rectangular extrusions 486 of thrust roller unit 463, to prevent thrust transfer unit 460 from rotating, while still being axially slidable. The remainder of rear casing 14 is suitable shaped to enclose the components of the CVT system 10.

Rear casing 14 is located in the CVT system 10 with plate 666 seated against front rim face 233 of structure body 56, while circular disc plate 670 abuts rear face 400 of rear spiral 28, and bolts 672 engage suitable threaded holes on face 233. 7. SERVO DRIVE 24

Referring to Figure 2, servo drive 24 includes a servo motor 700 with output spur gear 702. In the assembled CVT system 10, the servo drive 24 is attached against the servo flange 254 of the structure body 56 (Figure 10A) concentric with bore 260 through bolts engaging holes 262, while gear 702 meshes with spur gear 202 of ratio drive unit 64 in order to control the ratio of the CVT system 10.

Mathematical model of variable clamping Assuming the spring constant of the disk spring 572 of clamp unit 462 (Figures 21 A, 21 B) is K with unit N/mm. Further assume the maximum input torque at input sleeve 154 of radial shaft unit 60 is Tmax and that the highest ratio (i.e. drivers 362 positioned at the smallest radius with reference to axis W) is Rh:1 where Rh=1.2 and that the maximum clamping force at Tmax is Cmax. The maximum disk torque in this ratio will then be:

Tdiskmax=0.5 x Rh x Tmax N.m (each disk contributes 50% output torque) - Equation 2

Assume the disk spring 572 is preloaded (via adjustment of nut 578) to Preload with units in N. Define the variable clamping rate as: CR=(Cmax-Peload)/Tdiskmax in units of N/N.m Equation 3 In order to generate above CR, cam surfaces 622.1 and 622.2 with the following LC value is needed:

LC=0.5 x 2 x p x 1000/CR mm/rev - Equation 4 The maximum axial displacement between first cam 602 and second cam 604 can be defined as:

Dmax = Cmax/K mm - Equation 5

Therefore, Dmax needs to be equal to Lmax and, using Equations 1 to 5 above, the cam duration angle b can then be calculated as: b =360 x Dmax/(2 x LC) degrees - Equation 6

Above therefore provides a procedure to calculate LC and b for given values of Rh, Tmax, Preload and Cmax.

8. Second embodiment thrust transfer unit 460

The CVT system 10 functions in line contact traction drive between front disk unit 18, driver 362, and rear disk unit 20. This traction drive function, according to a function where slip in the traction drive is a function of input torque, is described in Naude, J., "Novel RADIALcvt Simulation and Test Results," SAE Technical Paper 2019-01-5021 , 2019. In the current embodiment, front disk unit 18 and rear disk unit 20 are coupled together in a 1 :1 ratio in opposite directions. This ratio is dictated by the two same size bevel gears 456 and 586. However, the rim 472.1 of roller 472 (of thrust roller unit 463) is also in traction drive line contact with face 458 of rear disk unit 20, and with peripheral rim 584 of clamp hub 568. Since the axis of roller 472 (of thrust roller unit 463) is perpendicular to the axis of front disk unit 18, this also results in a 1 :1 ratio in opposite directions. However, this 1 :1 ratio will only be sustained when no power is transmitted through roller 472 (of thrust roller unit 463) and thus when zero slip occurs.

Thus, bevel gear 456 of rear disk unit 20 and bevel gear 586 of clamp hub 568 (together with the two bevel gear units 464) can be eliminated and this gear drive will be replaced by a traction drive through roller 472 of thrust roller unit 463. However, this traction drive will now experience slip. Typical maximum slip as presented in the above referenced paper of Naude, J amounts to about 5%. In order to compensate for the slip, roller 472 (thrust roller unit 463) can be tilted (i.e. not be perpendicular to front disk unit 18 axis) to run on different radiuses on face 458 of rear disk unit 20 and clamp hub 568 and therefore change the above 1 :1 ratio to compensate for the slip. In such an embodiment, the rim 472.1 of roller 472 (of thrust roller unit 463) can be unchanged, while face 458 of rear disk unit 20 and peripheral rim 584 of clamp hub 568 are suitably angled to maintain line contact with the rim 472.1 . Roller 472, face 458 of rear disk unit 20, and peripheral rim 584 of clamp hub 568 may be optimised in any manner including curved, with point contact or any other means to optimize the drive.

This alternative embodiment would eliminate bevel gear 456 of rear disk unit 20 and bevel gear 586 of clamp hub 568, as well as the two bevel gear units 464 of thrust transfer unit 460, while the clamping force, as well as power transmission, is transmitted through rollers 472, whereas in the previous thrust transfer unit 460 embodiment the rollers 472 only transmitted the clamping force and the above mentioned bevel gears only the power transmission. 9. Clamping force functioning (basis for claim 1)

In WO2017143363 and WO2019239379, the clamping force was supported by two thrust bearings while the clamping force was also transmitted through the casing of the respective CVT system. In the current invention the clamping force, generated by the compression of disk spring 572 of clamp unit 462 (Figures 21 A, 21 B), follows the force path marked as A, presented in Figure 3, as follows. Starting in the traction drive line contact B between the rim 372 of driver 362 (Figure 13C) and disk face 424 of front disk unit 18 (Figure 15A), the force path follows through disk 416, hollow hub 426 of front disk unit 18, stepped-down shaft section 414.2 of output shaft 414, and up to threaded shaft end section 414.5 which is engaged with nut 578 of clamp unit 462. From shaft end section 414.5 the path follows through first cam 602, cam rollers 608, second cam 604 (first and second cam 602, 604 being in line contact with cam rollers 608), disk spring 572 of clamp unit 462 (Figures 21 A, 21 B), clamp hub 568, roller 472 of thrust roller unit 463, to rear disk unit 20 through the rim 472.1 of roller 472 (of thrust roller unit 472.1 ) in line contact with rear disk unit 20, and rim face 584 of clamp hub 568 (of clamp unit 462), back to driver 362 (Figure 13C) in traction drive line contact C with face 446 of rear disk unit 20. Above path A is not transmitted via the casing, but rather through the center of the CVT system 10 via stepped-down shaft section 414.2 of output shaft 414, which eliminates the two thrust bearings as presented in WO2017143363 and WO2019236049. As a result the input shaft cannot be located in the center of the transmission, as is the case in WO2017143363 and WO2019236049, but rather from the side via one of the radial shaft units 60C, while the gear coupling unit 62 distributes input power and torque from radial shaft unit 60C to radial shaft units 60A and 60B. The clamping force path A may also include the load cam unit 574 (of clamp unit 462), which adjusts the compression of disk spring 572 of clamp unit 462 (Figures 21 A, 21 B), and thus also the clamping force, based on the torque experienced by the rear disk unit 20, this torque being generated in traction drive location C (Figure 3). Load cam unit 574 can be eliminated, but this would result in a constant clamping force that can only be adjusted manually by nut 578 of clamp unit 462.

Note that the power transmission path may also follow above path A or deviate from path A and not pass through roller 472 but rather through meshing bevel gears 456,464 and 586.

Also note that the axes of radial shaft units 60A, 60B and 60C may not be perpendicular to the axis of front disk unit 18, but may be at an offset to 90° (axes Y and Z are not perpendicular), and that the rim 372 of driver 362 and mating traction drive at faces 424 and 446 may be modified to effect the offset. These modifications may include angle or curved faces that may have line contact or point contact. Above may have the effect that front disk unit 18 and rear disk unit 20 may turn in opposite directions at the same or at different speeds.

Also note that traction drive in the traditional sense refers to a hardened polished steel on steel interface lubricated in a traction fluid, for example like commercially available Santotrac series of traction fluids, but may include any other suitable materials, like ceramics instead of steel lubricated in a traction fluid or suitable fluid, or may not use a traction fluid or any fluid at all, but may be in dry friction drive. Thus, for the purposes of this invention, friction drive and traction drive may be used interchangeable.

Also note that any functioning of the current invention not described in detail is the same as the functioning described in WO2019236049.

10. Three-mode synchronous embodiment

A three-mode synchronous system 2011 , presented in a form suitable as a transmission for a front wheel drive passenger vehicle, is illustrated in Figures 23A and 23B, and includes the CVT system 10 of the invention, a three-mode unit 2001 , a mode helical gear 2002 and a differential unit 2003.

Figures 23 presents the CVT system 10 of the invention where the following have been hidden, namely the front casing 12, rear casing 14, oil pump 66, pump support 68, structure body 56, servo drive 24, ratio drive unit 64. Above hidden components and units can/may be relocated/modified/adapted/reconfigured/optimized/eliminated to suite their purpose in the current embodiment and is not further discussed. In the current embodiment, front disk unit 18 is modified by eliminating deep groove ball bearing 440, eliminating shaft section 414.1 , and including a bevel gear 2005, attached to hub 426, and a needle bearing 2007 located on shaft 414.6.

Three-mode unit 2001 Three-mode unit 2001 , which is illustrated in Figures 24 and 25, includes a first mode shaft 2013, a second mode shaft 2015, a low unit 2019, a high unit 2021 , a direct unit 2017, a selector 2023 and a reverse spur gear 2025.

First mode shaft 2013 First mode shaft 2013, which is illustrated in Figure 24, includes a shaft 2027 including a spur gear 2029, a bevel gear 2031 , a helical gear 2033 and another helical gear 2035. The shaft 2027 end is located in a needle bearing 2037 and two opposite facing taper roller bearings 2039 and 2041 bear against gear 2033 and 2035 respectively. Second mode shaft 2015

Second mode shaft 2015, which is illustrated in Figure 25A, includes a shaft 2043 including a spur gear 2045, a selector driver 2047 and a helical gear 2049. The ends of shaft 2043 locate two opposite facing taper roller bearings 2051 and 2053, bearing against gears 2045 and 2049 respectively. Selector driver 2047 includes external toothed splines 2055 on its outer rim.

Low unit 2019 Low unit 2019, which is illustrated in Figure 25D, includes a helical gear 2057, including a step 2061 on its front face, a cylindrical extrusion 2063, a central bore 2059, and external toothed splines 2065. On its rear face helical gear 2057 includes a cylindrical extrusion 2067. The central bore 2059 locates two spaced apart needle bearings 2071 and 2073.

High unit 2021

High unit 2021 , which is illustrated in Figure 25B, includes a helical gear 2075, including external toothed splines 2077 and a central bore 2079 locating needle bearings 2081 and 2083.

Direct unit 2017

Direct unit 2017, which is illustrated in Figure 25C, includes a helical gear 2085 including a step 2087 on its front face 2089, including a cylindrical extrusion 2091 terminating in a disk with external toothed splines 2093. Helical gear 2085 includes a center bore 2095 locating needle bearing 2097 and 2099. Selector 2023

Selector 2023, which is illustrated in Figure 25E, includes a disk body 2101 , including an external groove 2103, and a central bore with two rows of aligned internally toothed splines 2105 and 2107 adjacent the front and rear faces.

External toothed splines 2077, 2093, 2065 and 2055 are identical and complementarily shaped to engage and drive internally toothed splines 2105 and 2107.

Assembled three-mode unit 2001 In the assembled three-mode unit 2001 , shaft 2043 locates needle bearings 2097 and 2099 to rotatably locate direct unit 2017 between selector driver 2047 and helical gear 2049. Cylindrical extrusion 2091 locates needle bearings 2071 and 2073 to locate low unit 2019 rotatably between step 2087 and external toothed splines 2093 of direct unit 2017. Shaft 2043 locates needle bearings 2081 and 2083 to rotatably locate high unit 2021 with external toothed splines 2077 adjacent selector driver 2047. A needle bearing 2111 is located on shaft 2043 adjacent high unit 2021 . Helical gear 2033 and 2075 are meshed and helical gear 2035 and 2057 are meshed.

It is important to note that the selector 2023 selectively couples external toothed splines 2055 with any one of external toothed splines 2077, 2093 or 2065 via the engagement of the respective external toothed splines with internally toothed splines 2105 and 2107, as will be described in detail later. Note further that within three-mode unit 2001 , axial forces will be created by the helical gears and will also require axial limiting means. These can be a typical thrust needle, other thrust bearings and washers, or other means known in the art, and are not shown in the three-mode unit, as it is obvious to a person skilled in the art. Reverse gear 2025 is axially slidable and rotatably on a suitable idler shaft with an actuator (not shown) so as on demand to slide axially and couple and mesh with both spur gears 2045 and 2029, so as to couple second mode shaft 2015 and first mode shaft 2013 to rotate in the same direction. Differential unit 2003

Differential unit 2003 (Figure 23A) includes a helical gear 2110 and a typical differential (not shown) to which on either side the wheel drive shafts in a typical front wheel drive transmission is coupled. Assembled three-mode synchronous system 2011

In the assembled three-mode synchronous system 2011 , helical gear 2049 and 2110 are meshed, as well as helical gear 2085 and 2002, while helical mode gear 2002 is rotatably located around input sleeve 154 via suitable bearings (not shown). Bearings 2111 , 2037, 2051 , 2053, 2039, 2041 and 2007 are located in bearing pockets in suitable casing pieces, typically bolted together as is common in the trade and not shown. Synchronous three-mode operation Low mode

The selector 2023 is positioned to the far right top in Figure 24, and as illustrated in Figure 28B, and only couples shaft 2043 to gear 2057 of low unit 2019 via engagement of the selector 2023 with splines 2065. Drive is now from the input sleeve 154, through the CVT system 10 of the invention, to bevel gear 2005, to bevel gear 2031 and to shaft 2043 via the low unit 2019. Shaft 2043 includes gear 2049 which drives the differential unit 2003. The CVT system 10 can now continuously adjust its ratio from the largest radius position of follower units 320 (as presented in Figure 3) to the lowest radius position via servo drive 24.

Direct mode

The selector 2023 is positioned as presented in Figure 28A and only couples shaft 2043 to gear 2085 of direct unit 2017 via engagement of the selector 2023 with splines 2093. Drive is now from helical gear 2002 to gear 2085 of direct unit 2017 to shaft 2043 and to the differential unit 2003. In this mode the CVT system 10 is bypassed.

With the system in Low mode and with the CVT system 10 in its ratio with the follower units 30 in the lowest radius position, the ratio between the input sleeve 154 and shaft 2043 (via the CVT system 10) may be the same as the ratio between helical gear 2002 and shaft 2043, which will result in shaft 2043, direct unit 2017, and low unit 2019 rotating at the same speed in the same direction to allow selector 2023 to perform synchronous shifting between Low mode and Direct mode. The CVT system 10 inactive in Direct mode can now shift the follower units 30 to its largest radius position.

High mode The selector 2023 is positioned as presented in Figure 28C and only couples shaft 2043 to gear 2075 of high unit 2021 via engagement of the selector 2023 with splines 2077. Drive is now from the input sleeve 154 through the CVT system 10 to bevel gear 2005, to bevel gear 2031 , and to shaft 2043 via the high unit 2021 and to . Shaft 2043 includes gear 2049 which drives the differential unit 2003. The CVT system 10 can now continuously adjust its ratio from the largest radius position of follower units 30 (as presented in Figure 3) to the lowest radius position via servo drive 24.

With the system in Direct mode and with the CVT system 10 in its ratio with the follower units 30 in the highest radius position, the ratio between the input sleeve 154 and shaft 2043 may be the same as the ratio between helical gear 2002 and shaft 2043, which will result in shaft 2043, direct unit 2017, and high unit 2021 rotating at the same speed in the same direction to allow selector 2023 to perform synchronous shifting between Direct mode and High mode. The effect of above three-modes is as follows:

• The three-mode system is initially in Low mode and the CVT system 10 follower units 30 at the highest radius. In this Low mode follower units 30 is now adjusted to the lowest radius. • When in the lowest radius, selector 2023 engages Direct mode and the CVT system 10 becomes inactive. While in direct mode, the CVT system 10 can now adjust follower units 30 to the highest radius and the system can wait for the need to engage High mode. · When the need arises selector 2023 engages High mode, activating the CVT system 10, and the follower units 30 can now be adjusted from the highest radius to the lowest.

The above highest radius divided by the lowest radius provides the ratio range of the CVT system 10. The effect of the three-mode system is to extend the CVT system 10 ratio range to the power 2. For example, if the ratio range of the CVT system 10 is 3, the ratio range of the three-mode synchronous system will be 3 ² =9, thus vastly extending the ratio range. This methodology is similar to that presented in WO201 9239379.

Launching devices Single clutch embodiment

Input sleeve 154 may be attached to helical gear 2002 and may be coupled to the power source (for example internal combustion engine) via a conventional automated clutch. This clutch will only be used for pull-away, while mode changes via selector 2023 will require only very small duration engine power cuts to allow selector 2023 to perform the respective synchronous mode changes. Dual clutch embodiment

Input sleeve 154 may be attached to the first clutch and helical gear 2002 to the second clutch of a conventional dual clutch system, which may be coupled to the power source (for example internal combustion engine) via a conventional automated dual clutch. In this embodiment, Direct unit 2017 is permanently attached to shaft 2043. The first and second clutches may selectively be operated, as well as with clutch overlapping function, to allow mode shifts to be performed without any power interruption.

Pull away CVT system 10 bypass Fixed gearing, which includes a sprag (one-way clutch) in series, may be introduced between the direct unit 2017 and shaft 2043 to provide the same ratio between gear 2002 and mode shaft 2015 as the ratio between the input sleeve 154 and mode shaft 2015 when the CVT system 10 follower units 30 are in the largest radius position as in Figure 3. The sprag will only engage when the follower units 30 are in the above position and thus drive will be through the sprag and render the CVT 10 system inactive. Above will thus typically bypass the CVT system 10 during pull-away when large amounts of torque are required. As soon as the CVT system 10 ratio is adjusted, the sprag will freewheel and drive will be through the CVT system 10. This methodology is the same as presented in WO2019239379.