WO2007010566A1 - Ensemble de poulies pour une transmission variable continue - Google Patents

Ensemble de poulies pour une transmission variable continue Download PDF

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Publication number
WO2007010566A1
WO2007010566A1 PCT/IT2005/000415 IT2005000415W WO2007010566A1 WO 2007010566 A1 WO2007010566 A1 WO 2007010566A1 IT 2005000415 W IT2005000415 W IT 2005000415W WO 2007010566 A1 WO2007010566 A1 WO 2007010566A1
Authority
WO
WIPO (PCT)
Prior art keywords
pulley
shaft
support element
pulley assembly
support
Prior art date
Application number
PCT/IT2005/000415
Other languages
English (en)
Other versions
WO2007010566A8 (fr
Inventor
Alessio Galletti
Paolo Seta
Original Assignee
Dayco Europe S.R.L. Con Unico Socio
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 Dayco Europe S.R.L. Con Unico Socio filed Critical Dayco Europe S.R.L. Con Unico Socio
Priority to PCT/IT2005/000415 priority Critical patent/WO2007010566A1/fr
Publication of WO2007010566A1 publication Critical patent/WO2007010566A1/fr
Publication of WO2007010566A8 publication Critical patent/WO2007010566A8/fr

Links

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
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/32—Friction members
    • F16H55/52—Pulleys or friction discs of adjustable construction
    • F16H55/56—Pulleys or friction discs of adjustable construction of which the bearing parts are relatively axially adjustable
    • F16H55/563—Pulleys or friction discs of adjustable construction of which the bearing parts are relatively axially adjustable actuated by centrifugal masses
    • 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
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/66—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings
    • F16H61/662—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members
    • F16H61/66231—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members controlling shifting exclusively as a function of speed
    • F16H61/66245—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members controlling shifting exclusively as a function of speed using purely mechanical sensing or control means

Definitions

  • the present invention concerns a pulley assembly for a continuously variable transmission.
  • a continuously variable transmission includes a first pulley assembly connected to an .internal combustion engine, a second pulley assembly connected to the wheels of the vehicle and a belt wound between the two pulley assemblies.
  • Each assembly generally includes a shaft connected to the engine or to the wheels, a support element driven by the shaft, and a pair of half-pulleys rotationally connected in a rigid manner to the support element and mobile with regard to each other along the rotatable support element to define the transmission ratio.
  • one of the two pulley assemblies further includes a clutch to selectively couple the shaft to the support element to allow the drive of the half-pulleys.
  • Continuously variable transmissions are used on board scooters and, thanks to the increase in the transmittable power, also on board other vehicles such as three or four-wheel vehicles or on snowmobiles.
  • the aim 1 of the present invention is therefore to allow effective utilization of the engine brake in continuously ⁇ variable transmissions.
  • the aim of the present invention is achieved by a pulley assembly for a continuously variable transmission as defined in claim 1.
  • FIG. 1 is an axial section of a pulley assembly according to the present invention.
  • figure 2 is a left lateral view of figure 1 (not to scale) .
  • a pulley assembly for a continuously variable transmission is denoted by 1.
  • the assembly 1 includes a coupling shaft 2 rotating around an axis A and having an end portion 5 adapted to be rigidly connected to a driving shaft of an internal combustion engine
  • a ball bearing 3 and a freewheel support • 4 disposed on the coupling shaft 2 and a sleeve 7 supported coaxially on the coupling shaft 2 by the ball bearing 3 and the freewheel support 4.
  • the pulley assembly 1 includes on the opposite side of the end portion 5, a centrifugal clutch 8 to rotationalIy connect an end portion 6 of the coupling shaft 2 to the sleeve 7, a fixed half-pulley 9 rigidly connected to an end portion 10 of the sleeve 7 axially opposite to the centrifugal clutch 8, and a mobile half-pulley 11 slidable on the sleeve 7 between the fixed half-pulley 9 and the centrifugal clutch 8.
  • the fixed and mobile half-pulleys 9, 11 define a seat 13a which houses a belt 13 to transfer the power from the engine to a driven pulley assembly (not illustrated) connected to the wheels, and the axial position of the mobile half-pulley 11 is automatically set by a centrifugal control device 14 depending on the angular velocity of the sleeve 7 to vary the transmission ratio according to known methods.
  • the coupling shaft 2 has a longitudinal through hole 15 and defines, at the end portion 5, a conical seat 16 coaxial to the axis A and housing a corresponding coupling portion of a flange 17 adapted to be connected to the internal combustion engine and locked to the coupling shaft 2 by a screw 18 housed in the through hole 15.
  • the coupling shaft 2 Adjacent to the end portion 5 towards the centrifugal clutch 8, the coupling shaft 2 defines a support surface 19 for the freewheel support 4 which includes a cylindrical casing 20 rigidly connected to the sleeve 7 and two roller cages 22 housed inside the casing 20.
  • the freewheel support 4 besides includes, integrated within the casing 20, a freewheel coupling 23 axially interposed between the roller cages 22.
  • the freewheel joint 23 defines a unidirectional locking device and allows relative rotation when the coupling shaft 2 rotates faster than the sleeve 7, and the locking of the relative rotation when the speed of the sleeve 7 exceeds that of the coupling shaft 2, considering the rotation direction C indicated in figure 2 which coincides with the rotation direction of the engine and identifies a forward gear condition of the vehicle.
  • the ball bearing 3 On the opposite side to the flange 17, the ball bearing 3 is fitted to the end portion 6 of the driven shaft 2 and is locked in an axial direction against a shoulder 24 of the coupling shaft 2 by the screw 18.
  • the ball bearing 3 is housed inside a detachable portion 25 of the sleeve 7, for example a nut of suitable size, and defines together with the freewheel support 4 a radial support for the sleeve 7 on the coupling shaft 2.
  • the sleeve 7 is connected to the coupling shaft 2, in a rotationally decouplable manner, by the centrifugal clutch 8 which includes a disc support 27, a plurality of shoes 28 peripherally hinged to the disc support 27, a plurality of springs 50 to connect two adjacent shoes 28 with each other, and a drum 29 rigidly locked on the sleeve 7 by the nut 25 and housing the disc support 27.
  • the centrifugal clutch 8 which includes a disc support 27, a plurality of shoes 28 peripherally hinged to the disc support 27, a plurality of springs 50 to connect two adjacent shoes 28 with each other, and a drum 29 rigidly locked on the sleeve 7 by the nut 25 and housing the disc support 27.
  • the disc support 27 integrally includes a hub 30 which houses the end portion 6 of the coupling shaft 2 and is axially packed against the ball bearing 3 by the screw 18.
  • the disc support 27 defines a plurality of circumferentially equidistant holes 31, which house respective pins 32 parallel to the axis A and defining respective hinge axes B about which the shoes 28 rotate to selectively cooperate with the drum 29.
  • Each shoe 28 has a friction surface 33 having a curvature radius which is suitable to cooperate, under the effect of centrifugal acceleration, with an internal cylindrical surface 34 defined by the drum 29 and disposed coaxially to the axis A.
  • each shoe 28 has a center of gravity G in which are concentrated the inertial forces generated by the centrifugal acceleration and such center of gravity G precedes the respective pin 32, considering the direction C defining a forward ' gear condition of the vehicle, and directed in the rotation direction of the engine.
  • the direction C is anticlockwise and matches the rotation direction of the crankshaft .
  • curvature of the friction surfaces 33 and the position of the axes B are preferably devised in a way that a line of action of the friction forces between the shoe 28 and the drum 29 is interposed between the relative axis B and the internal cylindrical surface 34, thus obtaining an effect which will be better described as follows.
  • the drum 29 drives the centrifugal control device 14 which includes a guide element 35 rigidly connected to the drum 29 and a plurality of mobile rollers 36 housed ' inside a space 37 delimited on one side by the guide element 35 itself and on the other by the mobile half-pulley 11.
  • the mobile rollers 36 are housed in special radial slots (not illustrated) carried by both the guide element 35 and by the mobile half-pulley 11 and thus make the sleeve 7 circumferentially integral with the mobile half-pulley 11.
  • the pulley unit 1 is provided with a spring 38 cooperating axially with the guide element 35 and a detachable support 39 connected to the mobile half-pulley 11 and cooperating with the spring 38 to distance the half-pulley 11 from the fixed half-pulley 9.
  • the detachable support 39 includes a cylindrical wall 40 having an axial end portion rigidly connected to a peripheral portion 41 of the mobile half-pulley 11.
  • the detachable support 39 extends towards the centrifugal clutch 8 and houses the guide element 35 and has a radial rim 42 disposed at an opposite end with respect to the mobile half-pulley 11 and defining a stop facing the axis A for the spring 38, which is housed inside the cylindrical wall 40 between the radial rim 42 and a ring-shaped seat 43 facing the centrifugal clutch 8 of the guide element 35.
  • the operation of the pulley assembly 1 is as follows.
  • the pulley assembly 1 When the internal combustion engine is stationary or idling, the pulley assembly 1 is in an opening position in which the spring 38 keeps the half-pulleys 9, 11 apart thus defining a transmission ratio of maximum reduction which proves suitable for the pickup.
  • the coupling shaft 2 is rotationally driven and rotates inside the sleeve 7 which still remains stationary.
  • the coupling shaft 2 continues to accelerate exceeding a clutch threshold beyond which the shoes 28 open against the action of springs 50 and come into contact with the internal cylindrical surfaces 34 of the drum 29 while pushed by an approach force generated by the centrifugal acceleration.
  • the sleeve 7 and the half-pulleys 9, 11 are therefore friction driven and, during running, the transmission ratio is varied by the rollers 36 which are operated by the centrifugal acceleration and move radially on the guide element 35 pushing the mobile half-pulley 11 towards the fixed half-pulley 9 against the action of the spring 38.
  • an engine brake condition can also occur, in which the half-pulleys 9, 11 exert a driving torque on the coupling shaft 2 and the internal combustion engine resists such torque by slowing the vehicle.
  • the pulley assembly 1 allows continuous spanning of the transient state towards the engine brake state, thus avoiding annoying acceleration which would be produced if the half-pulleys 9, 11 were able to surpass the speed of the engine .
  • centrifugal clutch 8 is kept at high angular velocities which allow the drum 29 to be driven by the shoes 28 at least during an initial phase of the engine brake condition.
  • the spring 38 contributes in rapidly distancing the fixed and mobile half- pulleys 9, 11 to reaching the minimum transmission ratio.
  • Such ratio multiplies the number of revolutions of the half-pulleys 9, 11 in relation to the wheels of the vehicle thus keeping the pulley assembly 1 at a high angular velocity also at a relatively low vehicle speed and thus increasing the centrifugal acceleration.
  • the shoes 28 are assembled on the disc support 27 in a leading direction.
  • the resultant of the friction forces is directed from the opposite side of the relative axis B compared to the center of gravity G and influences in a negligible way the approach force which, in the pickup phase, is mainly generated by the centrifugal acceleration.
  • the centrifugal clutch 8 engages with initial slippage and the pickup is more gentle and suitable for the driving of a four-wheel vehicle, particularly during parking manoeuvres.
  • the half-pulleys 9, 11 can remain drivingly connected with the coupling shaft 2 until the engine has arrived at its minimum rpm number. Nevertheless such condition corresponds to a vehicle speed that is too low and which is not achieved in practice.
  • the pulley assembly 1 is directly constrained through the flange 17 to the internal combustion engine and drives, by the driven pulley assembly, a case including a differential gear to directly drive the wheels and a gearbox interposed between the driven pulley assembly and the differential gear and having a neurral gear, a forward gear and a reverse gear.
  • the engine immediately returns to its idling state, while the pulley assemblies tend to surpass the coupling shaft 2 due to the inertia acquired and cause gear grating resulting in damage.
  • the presence of the freewheel support 4 allows a concurrent deceleration, with the engine, of all of the variable ratio transmission and a subsequent smooth engagement of the forward gear .
  • the use of the freewheel support element 4 between ⁇ the coupling shaft 2 and the half-pulleys 9, 11 enables the engine brake to be used on board a vehicle endowed with the pulley assembly 1, thus preventing the occurrence of sudden and annoying acceleration during the transient state towards the engine brake condition or gearbox damage after accidental acceleration with the neutral gear.
  • the assembly cf the shoes 28 in the leading direction allows the shoes 28 to remain longer against the internal cylindrical surfaces 34 of the drum 29, thereby stressing less the service brakes.
  • the assembly in leading direction of the shoes 28 makes the pickup softer allowing more precise manoeuvring, without sudden jerks, example while parking.
  • the spring 38 allows the opening position of the half-pulleys 9, 11 to be reached more rapidly thus reducing the response times of the pulley assembly during the engine brake condition.
  • the freewheel support replaces the ball bearing 3 and that the support surface 19 guides a simple roller cage.
  • the shape of the friction surface 33 is of a size so that the axis B is interposed between the internal cylindrical surfaces 34 and the line of action of the resultant of the friction forces. In this case it is possible to maintain a gentle pickup, but the interval of speed is reduced within which the freewheel support 4 and the centrifugal clutch 8 jointly transfer to the coupling shaft 2 the driving torque received from the half- pulleys 9, 11 since the centrifugal clutch tends to disengage at a higher number of revolutions.
  • Continuously variable transmissions have various configurations, and by way of an additional variation it is possible to envisage a configuration in which both the clutch 8 as well as the freewheel support 4 are disposed on the driven pulley assembly.
  • both the clutch 8 as well as the control device 14 can be of a different type to that described, for example it can be operated automatically by actuators controlled by an electronic unit.
  • half-pulleys can be connected in various ways to the sleeve 7; in general, it is in ar.y case necessary that at least one of the two half-pulleys 9, 11 is rotationally connected to the sleeve 7.
  • the unidirectional locking device 23 can be made up for example of an electronically operated clutch.
  • the forward gear condition of the vehicle corresponds to an anticlockwise rotation of the coupling shaft 2, as shown in figure 2.
  • the rotation direction of the coupling shaft 2 is clockwise in the forward running condition of the vehicle, for example since a gear reduction unit is interposed between the internal combustion engine and the pulley assembly 1.
  • the assembly of the shoes 28 would mirror that shown, in figure 2.

Abstract

La présente invention concerne un ensemble de poulies (1) pour une transmission variable continue d’un véhicule, comprenant un arbre (2) doté d’un axe (A), un élément support (7) tournant autour de l’axe (A), une première demi-poulie (9) connectée de façon rotative à l’élément support (7), une seconde demi-poulie (11) faisant face à la première demi-poulie (9) pour définir un siège (13a) conçu pour loger une courroie (13) de la transmission, au moins une de la première et seconde demi-poulie (9, 11) étant longitudinalement mobile par rapport à l’élément support (7), et un embrayage (8) pour coupler sélectivement par rotation l’arbre (2) à l’élément support (7). L’ensemble de poulies (1) comprend en outre un moyen de couplage unidirectionnel (23) interposé entre l’élément support (7) et l’arbre (2) pour permettre l’entraînement de l’arbre (2) lorsque la vitesse angulaire de l’élément support (7) tend à dépasser celle de l’arbre (2).
PCT/IT2005/000415 2005-07-19 2005-07-19 Ensemble de poulies pour une transmission variable continue WO2007010566A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IT2005/000415 WO2007010566A1 (fr) 2005-07-19 2005-07-19 Ensemble de poulies pour une transmission variable continue

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IT2005/000415 WO2007010566A1 (fr) 2005-07-19 2005-07-19 Ensemble de poulies pour une transmission variable continue

Publications (2)

Publication Number Publication Date
WO2007010566A1 true WO2007010566A1 (fr) 2007-01-25
WO2007010566A8 WO2007010566A8 (fr) 2007-11-08

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Application Number Title Priority Date Filing Date
PCT/IT2005/000415 WO2007010566A1 (fr) 2005-07-19 2005-07-19 Ensemble de poulies pour une transmission variable continue

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010141730A1 (fr) * 2009-06-04 2010-12-09 The Hilliard Corporation Embrayage d'entraînement pour une transmission à variation continue avec frein moteur et protection de courroie intégrée

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH348063A (de) * 1955-11-29 1960-07-31 Uher Edmond Antriebsvorrichtung mit eingebautem Tretkurbelantrieb für Motorfahrräder
US3226994A (en) * 1961-07-28 1966-01-04 Harley Davidson Motor Co Inc Vehicle transmission and control
US4674359A (en) * 1982-02-08 1987-06-23 Honda Giken Kogyo Kabushiki Kaisha Vehicular speed change gear having a continuously variable transmission connected in series with a stepped gear transmission
JPH06330995A (ja) * 1993-05-24 1994-11-29 Kawasaki Heavy Ind Ltd ベルトコンバータ
US5514040A (en) * 1991-09-27 1996-05-07 Powerbloc Ibc Canada Inc. Variable-speed belt drive having toothed flyweights
EP0898096A1 (fr) * 1997-08-20 1999-02-24 TRANSFLUID S.r.l. Mécanisme d'entraínement à vitesse variable comprenant un embrayage centrifuge à friction
US20040214668A1 (en) * 2003-04-25 2004-10-28 Kawasaki Jukogyo Kabushiki Kaisha Automotive V-belt nonstage transmission

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH348063A (de) * 1955-11-29 1960-07-31 Uher Edmond Antriebsvorrichtung mit eingebautem Tretkurbelantrieb für Motorfahrräder
US3226994A (en) * 1961-07-28 1966-01-04 Harley Davidson Motor Co Inc Vehicle transmission and control
US4674359A (en) * 1982-02-08 1987-06-23 Honda Giken Kogyo Kabushiki Kaisha Vehicular speed change gear having a continuously variable transmission connected in series with a stepped gear transmission
US5514040A (en) * 1991-09-27 1996-05-07 Powerbloc Ibc Canada Inc. Variable-speed belt drive having toothed flyweights
JPH06330995A (ja) * 1993-05-24 1994-11-29 Kawasaki Heavy Ind Ltd ベルトコンバータ
EP0898096A1 (fr) * 1997-08-20 1999-02-24 TRANSFLUID S.r.l. Mécanisme d'entraínement à vitesse variable comprenant un embrayage centrifuge à friction
US20040214668A1 (en) * 2003-04-25 2004-10-28 Kawasaki Jukogyo Kabushiki Kaisha Automotive V-belt nonstage transmission

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1995, no. 02 31 March 1995 (1995-03-31) *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010141730A1 (fr) * 2009-06-04 2010-12-09 The Hilliard Corporation Embrayage d'entraînement pour une transmission à variation continue avec frein moteur et protection de courroie intégrée
AU2010256559B2 (en) * 2009-06-04 2013-05-16 The Hilliard Corporation Drive clutch for a continuously variable transmission with engine braking and built in belt protection
US8651986B2 (en) 2009-06-04 2014-02-18 The Hilliard Corporation Drive clutch for a continuously variable transmission with engine braking and built in belt protection

Also Published As

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