WO1990005864A1 - Systeme de transmission a entrainement par traction - Google Patents

Systeme de transmission a entrainement par traction Download PDF

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Publication number
WO1990005864A1
WO1990005864A1 PCT/US1989/004937 US8904937W WO9005864A1 WO 1990005864 A1 WO1990005864 A1 WO 1990005864A1 US 8904937 W US8904937 W US 8904937W WO 9005864 A1 WO9005864 A1 WO 9005864A1
Authority
WO
WIPO (PCT)
Prior art keywords
shaft
cvt
output
splitter
gearbox
Prior art date
Application number
PCT/US1989/004937
Other languages
English (en)
Inventor
Yves Jean Kemper
Original Assignee
Tractiontec Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tractiontec Corporation filed Critical Tractiontec Corporation
Publication of WO1990005864A1 publication Critical patent/WO1990005864A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • 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
    • F16H37/06—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts
    • F16H37/08—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing
    • F16H37/0833—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths
    • F16H37/084—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths at least one power path being a continuously variable transmission, i.e. CVT
    • 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
    • F16H15/48—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members with members having orbital motion
    • F16H15/50—Gearings providing a continuous range of gear ratios

Definitions

  • This invention relates to continuously variable power drive transmission systems and, more particularly, it concerns an improved multi-range transmission system of the type in which the input and output torques of a continuously variable transmission unit (CVT) are combined as system output torque through gearing in a manner to optimize system efficiency and speed ratio range in a compact system configuration.
  • CVT continuously variable transmission unit
  • It is well known in the continuously variable transmission art generally that the speed ratio range of a continuously variable transmission unit or CVT can be enhanced significantly by incorporating the CVT in a system by which system input is combined with the output of the CVT in epicyclic gearing.
  • a CVT in a transmission system including a power splitter and conventional multi-range gearing to achieve substantially stepless operation through a much wider range of continuously variable speed ratios than that of the CVT by itself.
  • a four shaft planetary gear power splitter may be used by connecting system input and CVT output with first and second shafts, respectively, of the splitter.
  • the third and fourth shafts of the splitter are connected alternately with the multi-range gearing to effect a "Mode A" operation in which the output speed of the CVT is subtracted from the system input speed and a "Mode B" operation in which CVT output speed is added to system input speed.
  • Exemplary disclosures of such systems may be found in U.S. Patent No.
  • down-shifting In all prior known systems involving multi-range CVT operation, down-shifting must occur in the same manner as up- shifting, that is, there is no potential for shifting between a fourth range and a first range in the context of multi-gear-ratio transmissions. As a result, down ⁇ shifting must occur with adjustments of the CVT through its increment of ratio ranges in down-shifting as well as upshifting because the clutch is used to obtain synchro- shifting are not capable of carrying the torque .loads required to increase the speed of the engine by clutch slippage- .Finally, the prior systems have involved a complex arrangement of gearing and control clutches which result in relatively large space consuming transmission systems found to be undesirable in conventional automotive use, for example.
  • a transmission system is provided by which a CVT is combined with a four shaft planetary gear power splitter and a multi-range gear box in a manner to enable highly effective, synchronized multi-range operation of the transmission system.
  • the CVT used in the system is preferably, but not necessarily, one having the desirable geometric configuration and proportions of the general transmission embodiments disclosed in U.S. Patent No. 4,856,371 in which no nutation of any CVT working body is required for operation.
  • the geometry of that CVT is used to combine system and CVT input in a common shaft and to provide a connection of system input and CVT output, respectively, to the first and second shafts of a four shaft planetary gear power splitter.
  • the splitter includes a pair of connected planet gears supported on a common carrier driven by the first shaft.
  • the second shaft drives an input sun gear of the splitter.
  • the third and fourth shafts of the splitter represent splitter output gearing having positive and negative basic ratios and axe alternately coupled with an output gear box.
  • the gear box preferably is in the form of a planetary gear set having a carrier shaft eccentric with respect to and connected directly to system output, an input sun gear and a releasably grounded ring gear.
  • a principal object of the present invention is, therefore, the provision of a highly compact, efficient continuously variable transmission system.
  • Another object of the invention is the provision of such a transmission system which enables down-shifting for engine braking operation without requiring CVT operation throughout adjacent system ranges.
  • Fig. 1 is a longitudinal cross section illustrat ⁇ ing a general embodiment of the present invention
  • Fig. 2 is a schematic view demonstrating one embodiment of the transmission system of the present invention
  • Fig. 2P is a table of parameters embodied in the transmission of Fig. 2;
  • Fig. 2T is a table showing the various operating parameters during different phases of system operation
  • Figs. 2A - 2E are schematic views depicting the flow of power through the gearing of the embodiment in Fig. 2 under different conditions of operation;
  • Fig. 3 is a schematic view illustrating an alternative embodiment of the invention.
  • Fig. 3T is a table similar to the table of Fig. 2T but representative of the values during operation of the embodiment of Fig. 3;
  • Fig. 4 is a curve illustrating the efficiency of the CVT 14 and the preferred operating modes.
  • Fig. 1 of the drawings shows the major components of a transmission system in accordance with the present invention and generally designated by the reference numeral 10. It is to be noted that while all the working components of the system 10 are not illustrated in this drawing figure, the external frame or housing designated by the reference numeral 12 from which the illustrated components are supported and both the upper and lower portions of the transmission system are fully illustrated in Fig. 1.
  • the system contained within the frame or housing 12 thus includes a CVT 14 and an arrangement of output gearing represented in block diagram form and designated generally by the rectangle 16. The gearing 16 will be described in more detail below.
  • the CVT 14 includes as major working components, an alpha body 18, a beta body 20 and an omega body assembly 22.
  • the alpha body 18, which may be generally circular in outline, includes a pair of inwardly directed trunnion bearings (not shown) for rotatably supporting opposite ends 24 and 26 of the beta body 20 about an axis 28 which is inclined with respect to and intersects a primary transmission axis 30 at a point S of axes intersection.
  • the alpha body extends inwardly to a pair of hubs 32 and 34, the outboard hub 32 being secured against rotation with respect to the housing 12 by a member 36.
  • the beta body 20 includes a central shaft 38 which extends throughout the length of the beta body to rotatably engage thealpha body trunnions at opposite ends 24 and 26. Slidably positioned on the shaft 38 are a pair of oppositely converging cone members 40 and 42. The cone members 40 and 42 are slidable axially of the beta body but secured for rotation therewith through a central shaft (not shown) in a manner more fully described in published international application WO88/07149.
  • the central shaft and the connection of the cone members 40 and 42 to threaded sections thereon is part of a system by which relative rotation between the beta body 20 and the alpha body 18 may be used to advance the cones 40 and 42 axially along the shaft 38.
  • the omega body assembly 22 includes a pair of plate members 44 and 46, each having a generally radial rolling surface of revolution 48 about the primary transmission axis 30 and supported by bearings (not shown) for rotation about the hubs 32 and 34 of the alpha body
  • the plates 44 and 46 are connected as a unit by an external torque cage 50.
  • the torque cage 50 is rotatably coupled with the omega plates 44 and 46 through ball ramp mechanisms (not shown) which operate to carry the plates
  • the cage as shown, is integral with a tubular input or omega shaft 52.
  • the beta body shaft 38 is linked to a CVT output or theta shaft 54 by a beveled gear 56, carried by or otherwise fixed to the shaft 38, which meshes with a beveled idler gear or theta body 58 carried by the alpha body 18 to be rotatable on an axis perpendicular to a plane including the axes 28 and 30.
  • the idler gear 58 meshes in turn with a beveled gear 60 on the theta shaft 54.
  • the inclusion of the idler gear or theta body 58 allows meshing of the gears 56,58,60 as simple bevel gears without any adverse effect as a result of varying the angle between the axes 28 and 30. While th significance of the gearing 56,58,60 will be described in more detail below, it will be noted from the components thus far described that rotation of the omega body cage
  • omega plates 44 and 46 will carry the omega plates 44 and 46 in rotation relative to the beta body 20 which, while rotatable on its axis 28, is fixed against rotational translation about the primary transmission axis 30 by virtue of the alpha body 18 being fixed at 36 to the housing 12.
  • the beta body cones 40 and 42 are retained in rolling friction engagement at two points or zones of contact with the surface 48 of the respective omega plates 44 and 46.
  • rotation of the omega plates 44 and 46 will cause rotation of the beta body 20 and its shaft 38 to drive the gear 56, the theta body 58, the gear 60 and the theta shaft 54.
  • the ratio at which the shaft 54 will be driven in relation to the input shaft 52 will be a function of the gearing 56,58,60 but more significantly the function of the relative radius of the cone members 40 and 42 and the omega plates 44 and 46.
  • the tubular input or omega shaft 52 extends to an input gearing unit 62 to couple the omega body to a source of power input, such as a flywheel 64 and crank shaft 66 of an internal combustion engine (not shown) .
  • the shaft 52 includes a terminal gear 68 which meshes with a ring gear 70 fixed to the fl wheel 64.
  • the lower portion of the tubular hub 32 of the alpha body 18 is windowed to permit the gears 68 and 70 to mesh.
  • transmission system is intended as designating the organization of power transmitting components and controls which operate to transmit power from the input shaft 52 to an output shaft 72 (Fig. 1) .
  • a transmission system as thus defined, is typically used with reduction transfer gearing which, though not necessarily a part of the transmission system, affect the relative meaning of other terms.
  • the term “overdrive”, for example, is commonly used in an automotive drive train context to mean that the final drive to the vehicle drive wheels operates at rotational speeds higher than the engine crank shaft 66 which is con ⁇ nected to the flywheel 64 in the illustrated embodiment.
  • the term “overdrive” means that the power output of the transmission system is driven at rotational speeds greater than the speed at which the system input (e.g.
  • CVT cardiac vacuum
  • system input the physical components functioning to input power to the CVT and to input power to the system may be embodied as one member (e.g., the shaft 52). Nevertheless, the terms are meaningful from the standpoint of understanding the respective speed ratios of the CVT as distinguished from the speed ratios of the transmission system including that CVT.
  • planetary gearing or "planet ⁇ ary gear set” as used herein and in the appended claims means an arrangement of planet gears supported by a carrier to provide a specific fixed gear ratio factor irrespective of whether the same gear set includes separate sun and ring gear components or whether one or the other of the sun and ring gear components of one planetary set are shared with another planetary set having a different gear ratio factor.
  • a compound planetary gearing arrangement capable of providing two gear ratios is the equivalent of two planetary gear sets.
  • the “basic ratio” or “ratio factor” of planetary gearing as used herein and in the appended claims is the ratio of rotation speed at an output component to the rotation speed of the input component when the planet carrier is grounded or held against rotation.
  • the terms “negative” and “positive” when applied to a ratio value is intended to denote the direction of a driving gear relative to a driven gear.
  • the ratio of a single driving spur gear and a single driven spur gear is negative because these gears rotate in opposite directions.
  • the ratio of a driving spur gear to an internal ring gear is positive because both driving and driven gears rotate in the same direction.
  • the gearing 16 included in the transmission 10 between the CVT 14 and the system output shaft 72 is depicted in block diagram form as including a power splitter 73, a multi- ratio gear box 75 and a control 77 by which the power splitter may be connected selectively with the gear box.
  • control as used in the legend of Fig. 1 is intended in a very general sense to include clutches, brakes and other such coupling devices used to couple various gear components to be described in which determine the speed ratio of the system 10.
  • Specific components of the gearing 16 may be seen and understood by reference to Fig. 2 in which an embodiment of the invention is illustrated with gearing and control components detailed in line form.
  • Fig. 2 an embodiment of the invention is illustrated with gearing and control components detailed in line form.
  • the power splitter 73 is a four-shaft planetary gear set having a first or carrier driving shaft 78, a second or sun driving shaft 80, a pair of coupled planet gears 82, a third shaft driven by a ring gear output 84 and a fourth shaft driven by a sun gear output 86.
  • System input power, as transmitted by the omega body 22, is connected at all times with the first or carrier driving shaft 78 of the splitter 73 whereas the CVT output at the theta shaft 54 is similarly connected to the second or sun driving shaft BO of the splitter 73-
  • the fear box 75 in the embodiment of Fi-g. 2, is a planetary gear set including a carrier 87, eccentric with respect to and connected to the system output shaft 72, a planet gear 88 on the carrier, a sun gear 89 and a ring gear 90.
  • Transmission of power between the splitter 73 and the gear box 75 is determined by the control 77 which includes releasable torque coupling devices or clutches designated by the reference characters Bl, Cl, C2, C3, C4 and DI in Fig. 2. While the function of each of the coupling devices in the operation of the transmission system will be more clearly understood from the table of Fig. 2T and the power path illustrations of Figs. 2A-2E, it will be noted with respect to Fig. 2 that the clutches C1-C4 function as synchronizing clutches in which clutch slippage is minimal if not non-existent. As a result, the clutches C1-C4 in practice are relatively lightweight and do not require constructions which require any accommodation for heat dissipation.
  • the clutches Cl and C3 and clutches C2 and C4 are respectively paired on the same member. Because the individual clutches of each such pair are not in the same condition of actuation at any time during operation of the transmission system, the clutches in each pair may share a push-pull class of actuator. In other words, a single hydraulically actuated member may be used to actuate both clutches of each pair C1,C3 and C2,C4 by actuation in opposite directions.
  • the other coupling devices used in the embodiment of Fig. 2 namely the coupling devices Bl and DI, are intended as brakes or clutches of a class which is capable of transmitting power with slippage. Both coupling devices Bl and DI, therefore, are isolated from other components of the gearing 16 and preferably positioned where heat dissipation is easily accommodated. For example, the location of the clutch Dl ⁇ externally of the transmission casing 12, is intended for this purpose.
  • the equation for the ratio of output speed ( ⁇ p) to input speed (e) is determined by the equation:
  • the value (P ⁇ ⁇ 2 ) represents the respective basic gear ratios of the splitter 73 using one of either the ring gear output third shaft 84 or the sun gear output fourth shaft 86.
  • the function (p) is the radius ratio of the CVT 14 at the contact points between the beta body cones 40 and 42 and their respective omega plates 44 and 46.
  • the geometry of the CVT 14 enables a radius ratio value for the function (p ) to extend from ap ⁇ proximately 0.783 to 2.88, the function (p) being at its minimum value where the points of contact between the beta body cones 40 and 42 and the omega plates 44 and 46 are nearest to the primary transmission axes 30 whereas the maximum value of (p ) is greatest or near 2.88 when the cones contact the omega plates at the outer ends or small -diameter portions of the -cones.
  • the internal -gear ratio K of the CVT 14, that is, the ratio of the gear 56 to the gear 60 is 1.277 or 1/0.783, the reciprocal of the minimum value of p , and causing the function (Kxp) to equal 1 at the minimum value of p .
  • the basic ratio of the gear box 75 or the function ⁇ 3 is related to the ratios V_ and P 2 of the splitter 73 in a manner such that the ratio of the system output speed ( ⁇ ) to the common CVT and system input speed ( ⁇ ) or ( ⁇ / ⁇ ) will be the same at opposite ends of operation with the output from the ring or third shaft to the splitter 73 (Mode A) and with output from the sun or fourth shaft of the splitter (Mode B) .
  • This condition is met by the exemplary parameters given in Fig. 2P of the drawings.
  • Fig. 2 The operation of the system embodiment illustrated in Fig. 2 is may clearly understood by reference to the table in Fig. 2T and the power path illustrations of Figs. 2A-2E in which applied members are shown in triple lines.
  • four forward ranges of operation are shown and identified in the first column of Fig. 2 as AL, BL, AH, and BH. These designations indicate a first range in which a low range of Mode A operation is followed by a low range of Mode B operation, followed by a high range of Mode A operation, followed by a high range of Mode B operation.
  • the relatively heavy duty coupling device or brake D2 is used to initiate transmission system operation from neutral or zero to an input/output ratio of 3.54.
  • the brake DI is used throughout the first two ranges of ratios shown in the table of Fig. 2T during which the input/output ratio is relatively high and correspondingly torque transmitted by the transmission is relatively high. As the input/output ratio approaches one and progresses to overdrive in the third and fourth ranges, where torque load is relativ light, the heavy duty brake DI is no longer needed for operation. Also, and as may be seen in Fig.
  • a reverse mode of operation is effected without use of the CVT 14 by energizing both relatively heavy duty brake devices DI and Bl.
  • the brake Bl enables a reversing idler 92 between the first shaft 78 of the splitter 73 and the planet pari 80.
  • the clutch C2 is energized or coupled prior to operation of either of the brakes Bl and DI.
  • FIG. 3 of the drawings an alternative embodiment of the system of the present invention is shown in which like parts are designated by the same reference numerals used in Fig. 2 and corresponding but slightly different parts are designed by the same reference numerals primed.
  • the embodiment of Fig. 3 differs from the embodiment Fig. 2 primarily in the substitution of a light-duty synchro-clutch C6 for the heavy-duty brake Bl and the inclusion of the reversing idler 92' in the output gearing 75 of the system.
  • the embodiment of Fig. 3 also enables operation using the CVT in Mode A operation to effect a variable range of reverse speed ratios.
  • the graph of Fig. 4 is included to relate operation of the present invention to efficiency of CVT operation.
  • basic efficiency of the transmission is represented by the horizontal line 94 whereas global efficiency of the transmission is represented by the curve 96.
  • the vertical line A represents the optimal initiation of Mode A operation in which the output speed of the CVT unit 14 subtracts from the system input speed.
  • slippage operation of the brake DI for example, is used to achieve the initial ratio of Mode A operation.
  • the CVT is operated at very high efficiencies throughout Mode A and B which, as indicated above, are alternated through full ranges of system operation.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transmission Devices (AREA)

Abstract

L'invention concerne un système de transmission de puissance variable en continu multi-régime comportant un arbre menant (52) et un arbre mené (72), une unité de transmission variable en continu (CVT) (14) comprenant un arbre d'entrée CVT (52) et un arbre de sortie CVT (54), une unité de répartition (73) de puissance à engrenage planétaire à quatre arbres dont un premier arbre (78) est entraîné par l'arbre menant et un second arbre (80) est entraîné par l'arbre mené CVT, un troisième arbre ayant un rapport de base positif (84), et un quatrième arbre (86) ayant un rapport de base négatif, ainsi qu'une boîte de vitesses (75) de sortie multi-régime destinée à entraîner ledit arbre mené. La boîte de vitesse se présente sous la forme d'un ensemble à engrenage planétaire doté d'un arbre porteur (87) excentrique par rapport à l'arbre mené (72) auquel il est raccordé, une roue solaire (89) ainsi qu'un engrenage annulaire (90) relié à la terre de manière libérable. On a prévu un dispositif de commande (77) se présentant sous la forme d'une pluralité de synchroembrayages (C1, C2, C3, C4) ainsi qu'au moins un embrayage (D1, C5) à frottement ventilé, afin de relier les troisième et quatrième arbres de l'unité de répartition à la boîte de vitesse de manière à obtenir au moins trois régimes synchrones de rapports de vitesse, chaque régime variant en continu par actionnement de la CVT jusqu'à un rapport de vitesse de 1:1 et inversement.
PCT/US1989/004937 1988-11-14 1989-11-13 Systeme de transmission a entrainement par traction WO1990005864A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US27063988A 1988-11-14 1988-11-14
US270,639 1988-11-14

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WO1990005864A1 true WO1990005864A1 (fr) 1990-05-31

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992010697A1 (fr) * 1990-12-11 1992-06-25 Torotrak (Development) Limited Transmission a variation continue du type a roulement-traction et a voie toroidale
US5401221A (en) * 1990-08-17 1995-03-28 Torotrak (Development) Limited Transmission of the toroidal-race, rolling-traction type having a mixer and a reducer epicyclic type gearing with clutches brakes
WO1997024539A1 (fr) * 1995-12-27 1997-07-10 Steyr-Daimler-Puch Aktiengesellschaft Procede de commande d'une boite de vitesses hydrostatique-mecanique a derivation de puissance dans des positions indeterminees d'embrayage

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2086491A (en) * 1932-04-11 1937-07-06 Adiel Y Dodge Variable speed transmission
US2716357A (en) * 1952-07-07 1955-08-30 Rennerfelt Sven Bernhard Continuously variable speed gears
US3203278A (en) * 1963-01-02 1965-08-31 Ford Motor Co Variable speed friction drive transmission
US4297918A (en) * 1978-06-23 1981-11-03 National Research Development Corporation Control systems for steplessly-variable ratio transmissions
US4355547A (en) * 1979-05-30 1982-10-26 Bl Cars Limited Continuously variable ratio transmission
US4630494A (en) * 1985-02-26 1986-12-23 Kemper Yves J Radially oriented nutational traction drive transmission
US4644820A (en) * 1986-02-03 1987-02-24 General Motors Corporation Geared-neutral continuously variable transmission
US4693134A (en) * 1985-06-20 1987-09-15 Excelermatic Inc. High-powered vehicle drive train
US4745821A (en) * 1986-11-21 1988-05-24 Bloomfield Research Limited Partnership Speed ratio adjusting system for nutational traction drive transmissions

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2086491A (en) * 1932-04-11 1937-07-06 Adiel Y Dodge Variable speed transmission
US2716357A (en) * 1952-07-07 1955-08-30 Rennerfelt Sven Bernhard Continuously variable speed gears
US3203278A (en) * 1963-01-02 1965-08-31 Ford Motor Co Variable speed friction drive transmission
US4297918A (en) * 1978-06-23 1981-11-03 National Research Development Corporation Control systems for steplessly-variable ratio transmissions
US4355547A (en) * 1979-05-30 1982-10-26 Bl Cars Limited Continuously variable ratio transmission
US4630494A (en) * 1985-02-26 1986-12-23 Kemper Yves J Radially oriented nutational traction drive transmission
US4693134A (en) * 1985-06-20 1987-09-15 Excelermatic Inc. High-powered vehicle drive train
US4644820A (en) * 1986-02-03 1987-02-24 General Motors Corporation Geared-neutral continuously variable transmission
US4745821A (en) * 1986-11-21 1988-05-24 Bloomfield Research Limited Partnership Speed ratio adjusting system for nutational traction drive transmissions

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5401221A (en) * 1990-08-17 1995-03-28 Torotrak (Development) Limited Transmission of the toroidal-race, rolling-traction type having a mixer and a reducer epicyclic type gearing with clutches brakes
WO1992010697A1 (fr) * 1990-12-11 1992-06-25 Torotrak (Development) Limited Transmission a variation continue du type a roulement-traction et a voie toroidale
GB2267323A (en) * 1990-12-11 1993-12-01 Torotrak Dev Ltd Continuously-variable-ratio transmission of the toroidal-race rolling traction type
GB2267323B (en) * 1990-12-11 1994-09-14 Torotrak Dev Ltd Improvements in or relating to continuously-variable-ratio transmissions of the toroidal-race rolling-traction type
US5453061A (en) * 1990-12-11 1995-09-26 Torotrak (Development) Limited Continuously-variable ratio transmission of the toroidal race rolling traction type
WO1997024539A1 (fr) * 1995-12-27 1997-07-10 Steyr-Daimler-Puch Aktiengesellschaft Procede de commande d'une boite de vitesses hydrostatique-mecanique a derivation de puissance dans des positions indeterminees d'embrayage
US6001038A (en) * 1995-12-27 1999-12-14 Steyr-Daimler-Puch Aktiengesellschaft Method of controlling a power distribution hydromechanical branched transmission in uncertain gear positions

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