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
  • 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 torque transmission apparatus and, more particularly, it concerns improvements in the construction of torque transmitting traction members by which normal force loading for the transmission of torque by friction to or from such members may be supported without objectionable deflection of transmission components.
• One preferred way of retaining the engaged rolling surfaces in contact under normal force loads adequate to achieve torque transmission by friction has been to provide the biconical body as an assembly of two conical members on ' a common shaft in concentric fashion and to connect the shaft with a cam system operable to forcibly separate the cone members along the axis of the shaft in response to a torque differential between the shaft and the cone members.
• a cam system operable to forcibly separate the cone members along the axis of the shaft in response to a torque differential between the shaft and the cone members.
• a biconical torque body which includes a pair of cone members subjected to severe diametrically opposite normal force loading is strengthened and rigidified to enable rotational support of the body at opposite ends without measurable deflection or axial misalignment of the rotating and nonrotating parts of each such rotational support. This is achieved by extending the small ends of the cone members to provide bearing shafts integral with the cone members. The shaft extensions of the cone members have a cross-sectional area of sufficient load resisting moment to carry the normal force loading on the body substantially without deflection.
• the bearing shaft extensions of the cones are of annular configuration to accommodate the control shaft. Since the central shaft carries only a small amount of the bending loads imposed on the torq-ue body, the diameter of the central shaft may be reduced to that necessary for handling torque loads only.
• the biconical body is con ⁇ stituted by two oppositely convergent cone members inter- connected without a central shaft at the respective base or large diameter ends thereof for relative rotation and axial displacement with respect to each other.
• the body is resistant to axial bending as a result of its geometric or biconical configuration and by transmission of bending stresses through a radial bearing which connects the base ends of the two cones.
• a pilot cone rigidly connected at its base to the base end of one of the cone members, extends to and is journalled concentrically within the small end of the other of the two cone members and thus further stabilizes the body against .the forces which act thereon.
• the two cone members of the latter embodiment are in axial abutment with each other through complementing cam or ramp surfaces preferably, but not necessarily, located at the concentric small ends of the pilot cone and the other one of the two cone members.
• the cam or ramp surfaces operate to convert torque acting between the cone members to an axial force or thrust acting to separate the cone members on the axis of . the biconical body.
• an adjustable preload force may be imposed on the cone members by a set screw arrangement acting between them.
• a principal object of the present invention is, therefore, to reduce to a minimum the deflection of a torque transmitting body of the type referred to and which is supported on its ends by bearings in opposition to diametrica opposed axially spaced normal force loads.
• Fig. 1 is a longitudinal cross-section of an infinitely variable transmission incorporating one embodiment of the present invention
• Fig. 2 is a longitudinal cross-section through another continuously variable torque transmission incor ⁇ porating an alternative embodiment of the invention
• Fig. 3 is an enlarged fragmentary cross-section in the same cutting plane as Fig. 2;
• Fig. 4 is an enlarged fragmentary section similar to Fig. 3 but illustrating components in a different orienta ⁇ tion;
• Fig. 5 is an exploded side elevation illustrating components shown in Figs. 2-4;
• Fig. 6 is an end view as seen on line 6-6 of Fig. 5.
• an infinitel variable transmission unit incorporating the present inventio is generally designated by the reference numeral 10 and shown to include a casing or frame 12 from which working components or bodies of the transmission are supported.
• a supporting body 14 is mounted at opposite ends by axle-like extensions 16 and 18 in casing end walls 20 and 22 to be generally concentric with a primary or first " axis 24.
• the extensions 16 and 18 and thus the body 14 are retained against rotation on the axis 24 -by interlocking spline sets 26 and 28, for example.
• a generally cylindrical body 30 is supported from the extensions 16 and 18 and thus from the frame 12 to be rotatable about the first axis 24 by bearings 32 and 34.
• the body 30 carries a pair of axially spaced rings 36 and 38 defining internal traction surfaces 40 of revolution about the first axis 24.
• the rings rotate with the body 30 and are axially adjustable toward and away from each other by appropriate control means such as one or more, preferably three oppositely pitched threaded screws 42 adapted to be driven in rotation on their respective axes by means (not shown) .
• a biconical body is supported by the body 14 for rotation about a second axis 46 which is inclined with respect to the first axis 24 and intersects the first axis at a point S of axes intersection.
• the body 44 functions as a unit, it is comprised of separate components in the embodiment of Fig. 1,. such components including a pair of oppositely convergent cone members 48 and 50 defining conical traction surfaces 52 of revolution about the axis 46.
• the conical surfaces 52 converge at an apex angle which is twice the angle at which the axes 24 and 46 intersect.
• the traction surfaces 52 on the cones 48 and 50 may be in continuous contact with the traction surfaces 40 on the rings 36 and 38 throughout all axial positions of the rings.
• a ball/ramp assembly 54 Separating the base ends of the conical members 48 and 50 is a ball/ramp assembly 54 including a pair of plate members 56 and 58 biased away from each other under a spring preload developed by a Belleville spring washer set 60.
• the plates 56 and 58 as well as the base ends of the conical members 48 and 50 are formed having complementing ramp surfaces to engage two pairs of balls 62 and 64 which operate to force the cone members 48 and 50 in opposite directions away from the point S of axes intersection in a manner to be described in more detail below.
• the conical members 48 and 50 are provided with through-bores 66 and 68 concentric with the axis 46 to fit the external dimensions of a central shaft 70.
• the shaft 70 includes splines 72 positioned centrally along its length to effect a rotational coupling of the ball/ramp plates 56 and 58 with the shaft 70. Also, the shaft 70 makes a close rotatable and sliding fit at opposite end portions of each of the cone members 48 and 50 in a manner permitting relative rotation and axial movement of the cone members 48 and 50 and the shaft 70.
• At least .one end of the shaft 70 is keyed with a bevel gear 74 which, in the illustrated embodiment, is in direct meshing engagement with a gear 76 on a shaft 78 journalled in part by a bearing 80 to be independently rotatable with respect to the body 14.
• a thrust bearing represented by a ball 81 in the drawing is positioned between one end of the shaft 70 and a bracket 82 fixed to the supporting body 14.
• the opposite end of the shaft 70 is similarly constrained by a washer 83 abutting a portion of
• the cylindrical body 30 carries a gear or sprocket 84 by which the body 30 may be driven in rotation about the axis 24.
• the torque differential between the conical member 48 and 50 and the shaft 70 is through the balls 62 and 64 which, because of the ramp surfaces in which they are situat will develop an axial separating force on the conical member 48 and 50 proportional to the torque differential.
• the traction surfaces 52 on the conical members will be urged into engagement with the traction surfaces 40 under normal force loading proportional to the output load on the shaft 80 in the example given. Because the points PI and P2 of contact between the surfaces 40 and 52 are diametrically opposite from each other, the normal force loading will develop a rocking couple in a direction which, if unopposed, 'would reduce the angle at which the axes 24 and 46 intersect each other.
• the rocking couple is opposed exclusively by bearings 86 and 88 by which opposite ends of the body 44 are supported rotatably in the body 14. Because of the different moment arms ' in the rocking couple resulting from normal force loading and the reaction • couple developed by the bearings 86 and 88 there is a tendency for the biconical body 44 and the shaft 70 thereof to be deflected into an S-shaped curve in which the axis 46, when so curved, would intersect the point S and two points centered with the bearings 86 and 88. Such deflection is the result of bending stresses which are substantially equal and opposite along each half-length of the shaft between the respective bearings and the point S.
• deflection in the biconical body 44 between the point S and the bearings 86 and 88 is substantially avoided by providing each of the cone members 48 and 50 with integral shaft extensions 90 and 92 from the small diameter ends of the conical traction surfaces 52. Because the shaft 70 is reduced to a diameter capable of handling exclusively the torque and shear loading on the shaft 70, the shaft extensions 88 and 90 are increased in radial- thickness. Resistance to biconical body deflection as a result of the normal force loading of the traction surfaces 52 is borne entirely by the cone members 48 and 50. Because the conical members are formed of high strength materials of the type used for bearing rollers, and also because of the increased diameter of these members and of the shaft extensions 90 and 92, deflection along the axis 46 is substantially avoided.
• the bearings 86 and 88 are preferably hydrodynamic bearings having an inner race defined directly by the shaft extensions 88 and 90 and an outer race or bushing 96 seated in the body 14.
• the cylindrical interface between the races 94 and 96 is supplied with a lubricant under high pressure supplied by external piping 98 through internal passageways 99 and 100 in the body 14 and the shaft 70, repsectively.
• the facility for the use of hydrodynamic bearings in the support of the biconical body 44 is important not only from the standpoint of accommodating the loads imposed at the gears and the indefinite life characteristics of hydrodynamic bearings, but also, such bearings will enable the necessary slight degree of axial movement in the cone members 52 resulting from elasticity of the material from which the cone members 48 and 50 as well as the rings 36 and 38 are formed. Also, the avoidance of loads on the shaft 70 which tend to cause a relative deflection between the shaft 70 and the cone members 48 and 50 is important from the standpoint of avoiding a direct torque differential between the cone members and the shaft. In particular, any direct transfer of torque from the shaft 70 to the cone members would reduce torque seen by the balls 62 and 64 and reduce the effective normal force loading of the surfaces 40 and 52 to below that which is necessary to transmit a given output torque load on the shaft 80.
• the relative torque arm lengths when the rings 36 and 38 are positioned at the base or large ends of the cone members reduce the effect of the unwanted cone-shaft frictio because less normal force development by the ball/ramp assembly 54 is needed for the transmission of a given torque, at the base end of the cones than is needed for the trans ⁇ mission of the same torque at the small ends of the cones.
• a lower efficiency of ball/ramp operation can be tolerated under conditions of transmission operation when friction between the central region of the shaft 70 and the cone members is maximum.
• the input shaft 114 is connected as an integral shaft extension with a body 118 supported in the frame 112 by bearings 120 and 122 for rotation about a first axis 124.
• the body 118 is similar to the body 14 in the transmission of Fig. 1 but, in this instance, is rotatable as a cranking body.
• the biconical body 110 is supported directly from the cranking body 118 by bearings 126 and 128 to be rotatable on a second axis 130 inclined with respect to and intersecting the first axis 124 at a point S of axes intersection.
• rings 132 and 134 Supported by and coupled against rotation with respect to the frame 112 are a pair of rings 132 and 134 which are capable of axial adjustment toward and away from the point S of axes intersection.
• such axial adjustment of the rings 132 and 134 is effecte by one or more oppositely pitched screws 136 rotatable by an external control (not shown) through gears 138 and 140 which are rotatable on axes fixed with respect to the frame 112.
• An additional control gear 142, rotatable with respect to the frame 112 is shown and in practice is used to synchroni rotation of the gear 140 with corresponding gears for additi sets of double pitched screws (not shown) .
• a pinion gear 144 connected directly to the biconical body 110 in a manner which will be described in more detail below, meshes with a ring gear 146 coupled directly with the output shaft 116.
• the biconical body 110 in the illustrated embodiment defines a pair o . -external conical surfaces 148 and 150 of revolution about the axis 130 and which function as rolling or traction surfaces.
• the surfaces 148 and 150 engage complementing internal traction surfaces on the rings 132 and 134 at two diametrically opposite points of contact PI and P2.
• the rotational speed of the output shaft 116 in this instance is the product of both rotation of the cranking body 118 on the first axis 124, causing orbital or planetary movement of the pinion gear 144, and rotation of the pinion gear with the biconical body o
• the biconical member 110 undergoes a nutational movement as a result of its being supported on the second axis 130 by the cranking body 118.
• the biconical body 110 may be concentric with the first axis 124 and coupled directly with an output shaft whereas the rings 132 and 134 are concentric with the second axis 130 and, as such, carried in nutation by the equivalent of the cranking body 1-18.
• the structure and function of the biconical body 110 is equally applicable to either form of transmission in this general class.
• the conical surfaces 148 and 150 are the external surfaces of two cone members 152 and 154, respectively. Both cone members 152 and 154 are hollow and extend at their small ends as cylindrical inner race portions 156 and 158 for rotatable support by the respective bearings 126 and 128. Each of the two cones has a relatively large diameter or base end 160, 162 shaped to define telescopic journal formations 164 and 166, which define respectively, outer and inner races of a radial bearing 167. As a result of the journal formations and the bearing 167, the cone members 152 and 154 may rotate relative to each other and also slide longitudinally along the axis 130 in relation to each other.
• the pinion gear 144 by which torque is transmitted from the biconical body 110 to a driven load through the output shaft 116 is coupled for rotation with the body 110.
• the sole direct connection of the pinion gear 144 to the body 110 is with the cone member 154.
• the gear 144 is formed as an integral extension at the small end of the cone member 154.
• the base end 162 of the cone member 154 is secured, such as by welding, to the base end 168 of a pilot cone 170, the small end 172 of which is rotatably and slidably supported by a radial bearing 173 formed between the exterior of the end 172 and the interior of the bearing race portion 156 at the small end of the cone member 152.
• a cam or ramp assembly 174 operates as the sole torque transmitting coupling between the cone member 152 and the pinion gear 144 through the pilot cone 170 and the cone member 154 in a manner to be described in more detail below.
• the cam assembly 174 is located within the bearing race portion 156 at the small end of the cone member 152. As shown most clearly in Figs. 3-6 of the drawings, the assembly 174 includes a thrust plate or plug 176 threadably or otherwise anchored against axial displacement with respect to the cone member 152, a cylindrical cam member 178 coupled by splines 180 for direct rotation with the cone member 152 and a complementing cylindrical cam portion 182 integral with or otherwise nonrotatably fixed at the small end 172 of the pilot cone 170. A set screw 184 is threadably received in the thrust plate 176 and is in abutting relationship with the cam member 178. As may be seen by comparing the illustra tions in Figs.
• the splines 180 are of a length sufficient to enable the cam 178 to be adjustably positioned axially in the race portion 156 of the cone member 152 by appropriate adjustment of the set screw 184.
• cam members 178 and 182 are each provided with complementing annular end camming faces 186 and 188, respectively. These surfaces define a ramp angle by which an angular or rotational force (i.e. torque) is resolved into an axial component of force operatin to separate the cam members 178 and 182 axially.
• the axial separating force is, therefore, proportional to torque transmitted between the cam members 178 and 182 and the magnitude of that axial force for a given torque will be determined by the ramp angle of the engaged camming surfaces.
• 186 and 188 The camming surfaces 186 and 188 are, moreover, bidirectional in the sense that the same axial component of force will be developed irrespective of the relative direction of torque transfer between the cam members 178 and 182.
• the torque transmitted at the points PI and P2 will be equal, in the same direction and, as such, represent an equal division or splitting of torque delivered to the pinion gear 144.
• the set screw 184 has been adjusted to preload the conical surfaces 148 and 150 into engagement with the inner surfaces of the rings 132 and 134, no relative movement between the cone members 152 and 154 will occur at torque loads on the output shaft until the normal force required at the point P2 exceeds that developed by the set screw preload.
• the magnitude of torque transmitted by the cam assembly 176 will be only one-half the magnitude of the torqu load at the gear 144 because it is the torque carried only by the cone member 152.
• the magnitude of the axial force component developed by the cam assembly 176, however, and the resulting normal force loading at the contact points PI and P2 will be a function of the ramp angle of the engaged camming surfaces 186 and 188. By design of the ramp angle, therefore, the normal force loading of the conical surfaces 148 and 150 against the rings 132 and 134 may be made proportional to torque loads on the output shaft.
• an improved torque transmitting body structure is provided for continuously variable torque transmissions of the type exemplified in the drawings.
• the integral extension of the cone members to provide substantially the complete support of the biconica body takes maximum advantage of the biconical geometry of the body as well as the materials used in the cones to resist bending loads imposed on the body.
• the embodiment of Figs. 2-6 further demonstrates such additional characteristic as simplicity and adaptability of the structure either to a hollow construction as shown or to a solid cone construction at least of the cone 154 and pilot cone 170. This latter characteristic also paves the way to consideration of materials other than high strength bearing alloys for use in the cones, such as less expensive steels and synthetic resinous or plastic materials, particularly in transmissions

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

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• 1980
  • 1980-04-23 GB GB8038268A patent/GB2062146B/en not_active Expired
  • 1980-04-23 JP JP50110480A patent/JPS56500467A/ja active Pending
  • 1980-04-23 WO PCT/US1980/000448 patent/WO1980002449A1/en not_active Application Discontinuation
  • 1980-05-02 IT IT8067694A patent/IT8067694A0/it unknown
  • 1980-05-05 CA CA000351282A patent/CA1137335A/en not_active Expired
  • 1980-09-19 JP JP50237380A patent/JPS56501212A/ja active Pending
  • 1980-11-17 EP EP19800900934 patent/EP0029830A4/de not_active Withdrawn
• 1981
  • 1981-01-02 SE SE8100002A patent/SE439670B/sv unknown

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