The invention relates to a continuously variable friction roll toroidal drive comprising two variator disks that are rotatable about a common roll axis and which have tracks which are part of the circumferential surface of a torus concentric with the variator roll axis, and in contact with the tracks is a plurality of rollers which are journaled each in a housing with which a support is associated connected with a hydraulically operated piston, the axis of rotation of each roller being able to turn about an axis which is inclined at a certain angle (castor angle) to the central plane of the torus.
A conventional friction roll torus drive of this kind is represented in a side view in
A continuous drive of this kind operates properly whenever a hydraulic fluid in the cylinder 15 exerts a force on the piston 14, which in the state of equilibrium has to equalize the reaction force that originates from the resultant torque at the point of contact of the roller 9 with the tracks 6 and 7. The roller 9 changes its orientation of the angle of inclination of its axis of rotation 11 with respect to the variator roll axis 5 if the conditions of equilibrium of the applied forces are not satisfied.
The center point of the roller 9 must always follow the center circle of the torus, which in turn lies in the center plane M of the torus. For the reason to be given below, the rod 13, which defines the axis of rotation of the roller 9, is inclined at an angle C to the center plane M. In order for the roller 9 to be able to assume a stable transmission position on the basis of its degrees of liberty, the roll axis 11 of roller 9 must be able to intersect with the roll axis 5 of the variator disks 1 and 2. In case of a shift in the direction of action of the rod 13, the roller 9 comes out of its stable position and makes its adjustment. To be able to resume a new stable position, the angle C between the axis of roller 9 that is defined by the piston shaft 13 and the center plane M of the torus defined by the tracks 6 and 7 is necessary. This angle C, called the castor angle, makes it possible, due to kinematic rules, for the above-described roll axes 11 of the roller 9 to relocate independently its intersection with the variator roll axis 5 and achieve a stable position. The rule in this case is that the self-stabilization of the roller 9 increases with the increasing castor angle. The circumstance that the thrusting force produced by the piston 14 is inclined by the castor angle C toward the center plane M of the torus results, however, in an unequal thrusting force of roller 9 against the two variator disks 1 and 2. This unequal distribution of force increases with an increasing castor angle. As it appears from
Another disadvantage of the introduction of the thrust for the rollers at an angle to the center plate M of the torus is an unfavorable positioning of the cylinder 15 in the drive, which can even necessitate a bent shape of the rod 13. But the consequence of such a bent shape of the rod 13 is that a tilting moment is applied to the piston 14.
The invention is addressed to the problem of creating a friction roll toroidal drive of this kind, in which the force necessary for the thrust of the rollers has no component in the direction of the variator roll axis.
This problem is solved by the invention in that the direction of the thrust of each roller lies in the central plane of the torus, that each roller is mounted for rotation on a turning body, and that the turning body is mounted for rotation in the housing, the swing axis of the turning body being inclined at a specific angle (castor angle) to the central plane of the torus.
The angular positioning of the swing axis of the turning body, which can be freely chosen structurally, with respect to the center plane of the torus, results in the kinematic prerequisite, so that when the turning body turns, the roll axis of the roller journaled thereon can intersect with the roll axis of the variator disks. Due to the separation of the castor angle and the direction of the thrust of this roller, it is possible to position the direction of the thrust of each roller in the center plane of the torus. Thus a uniform distribution of force in the contact point of each roller with the two variator disks is possible. This signifies a reduction of the thrust of the variator disks against the rollers and an increase in the overall efficiency.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
In FIGS. 1 to 3 is shown only one of the two variator disks 20 of a toroidal drive which can rotate about a variator roll axis 21. Also, only one of several rollers 22 is shown, which is in contact with the track 34 of the variator disk 20 and can rotate about a roller axis 23. Important to the invention is the manner in which each roller 22 is mounted in the associated housing and the way in which the housing is supported against the reaction force exerted by the roller in operation. As far as the other constructional and functional details of the toroid drive are concerned, see the introductory explanation of
In a fixedly disposed cylinder housing 24 a piston 25 is arranged which can be acted upon bilaterally by a hydraulic fluid. The piston 25 is fastened on a piston shaft 26 which is guided for axial displacement in the cylinder housing 24. On the end of the portion of the piston shaft a link pin 27 is fastened. The housing of the roller 22 comprises a fork 28 which has two lugs 29 pointing away from the roller 22, through which the pin 27 rotatably passes. As it can be seen in
The second and third embodiment of a toroidal drive shown in
In the embodiment shown in
The third embodiment shown in
If the castor angle C, i.e., the angle between the axis of rotation defined by the pivot pin 33 and the center plane M of the torus, is changed, then it is necessary only to turn the pin 32 in the fork 28 and then tighten it again.
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
Number | Date | Country | Kind |
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102 23 425.6 | May 2002 | DE | national |
This application is a continuation of International Patent Application No. PCT/EP03/04309, filed Apr. 25, 2003, designating the United States of America, and published in German as WO 03/100294 A1, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on German patent application no. 102 23 425.6, filed May 25, 2002.
Number | Date | Country | |
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Parent | PCT/EP03/04309 | Apr 2003 | US |
Child | 10990969 | Nov 2004 | US |