EP1025374A1

EP1025374A1 - Friction gear

Info

Publication number: EP1025374A1
Application number: EP97948819A
Authority: EP
Inventors: Herbert Bolter
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-10-28
Filing date: 1997-10-28
Publication date: 2000-08-09
Also published as: AU6909798A; WO1998019080A1

Abstract

Disclosed is a friction gear comprising at least one driving surface (70c, 70d) and at least one driven surface (71d, 71d') and, installed between both, at least one intermediate member featuring a set of bearing balls (17, 18, 19), and both the driving surface (70c, 70d) ant the driven suface (71d, 71d') have a toroidal camber. At least two, preferably three, bearing balls (17, 18, 19) are placed in series for the purposes of driving. In another embodiment, the bearing balls are mounted sliding and pivoting, thereby enabling the ratio of transmission and the initial tension to be adjusted.

Description

FRICTION GEARBOX

The invention relates to a friction wheel transmission according to the preamble of claim 1 and claim 5.

Such friction gear are known for example from EP-A1-021 126, DE-PS 23 61 993 or from "Dubbel, Taschenbuch für den Maschinenbau", 16th edition 1987, G 104-108. A stepless adjustment of the transmission ratio is made possible in these gears by shifting the radial position of the rolling element.

For example, WO 92/08912 and WO 83/02986 describe friction wheel transmissions with toroidal or curved friction surfaces. The gear unit disclosed in WO 92/08912 provides disc-shaped rolling elements, the adjustability of which depends on the particular operating state. Unrestricted adjustability is not possible without appropriate wear. The gear unit disclosed in WO 83/02986 shows a double ring of spherical rolling elements, one ring of rolling elements each transmitting torque, the double ring as such being essentially intended to absorb supporting forces.

In known friction wheel gears there is also a problem in the generation of sufficient contact pressures between the disks or shafts and the rolling elements, which in the conventional gears are provided either by a spring force or by means of relatively complex devices for generating a torque-dependent axial force.

In contrast, the invention has set itself the task of providing friction wheel transmissions which remedy the disadvantage which has become known from the prior art, can furthermore be switched without restrictions, for example by generating a torque-dependent preload, and in which occurring

APPROVAL $ KQPi £ Axial forces are not dissipated via the housing but via the shaft (s).

This is achieved by realizing the characterizing features of claim 1 or claim 5. Advantageous or alternative embodiments are described by the features of the dependent claims.

Axial tensions are dissipated within the shafts, the slidability under load runs with a corresponding number of balls or geometry of the running surfaces as a pure rolling motion, with a corresponding number of balls also independent of the respective operating state and, if necessary - depending on the position of the rolling elements - also for setting the preload automatically. Another advantageous property of the friction wheel transmission according to the invention is the possible duplication of the torques.

The invention is described below purely by way of example with reference to the drawing. Show it:

Fιg.1 a friction gear with curved friction surfaces and

Intermediate links with two spherical rolling elements, in which there is a multiplication of the torques

2a shows the schematic representation of the arrangement of several intermediate members, each with three rolling elements in a friction gear with toroidal running surfaces;

2b shows a variant with multiple arrangement accordingly

3a, 3b, 3c show schematic representations of the adjustability of three drive elements with different cages arranged in series in the drive between two friction surfaces; 4 shows a schematic top view of a further exemplary embodiment with mutually parallel friction surfaces; 5 shows a side view of a friction gear according to FIG. 4;

6 shows a schematic side view of a further exemplary embodiment with a plurality of drive disks and driven disks arranged between them;

7 shows a section along A-B of Figure 6;

8a and 8b a top view and a side view of a

Exemplary embodiment with a friction surface-bearing shaft and disk and FIG. 8c shows a detail B from FIG. 8a.

In the first exemplary embodiment of the invention shown schematically in FIG. 1, a driven disk 2a is rotatably mounted on a shaft 5 between two drive disks 1a and 1b. Between the curved, here toroidal, drive surfaces 70a and 70b of the disks 1a and 1b and the likewise curved, also toroidal, driven surfaces 71a and 71b of the disk 2a, there is a non-positive connection between which the first and second rolling elements 7, 8 in the form of balls are arranged in series with one another in terms of drive, which convey the rotational movement of the disks 1a and 1b to the disk 2a via three friction points 9, 10, 11 in a frictional manner. The rolling elements 7, 8 are arranged in a common cage 15 (indicated by dashed lines), which can also be designed as a ball-bearing plate. The direction of rotation of the disks 1a and 1b and 2a is in each case the same direction; when the radial position of the rolling elements 7, 8 is pivoted, the gear ratio is changed. The preload can be generated from the inside via the two rolling elements, in contrast to the situation as in WO

92/08912, in which disk-shaped rolling elements are shown.

The arrangement multiplies the torque transmission via the multiple intermediate links and the parallel arrangement of the friction surface situation. 2a and 2b show friction wheel transmissions in which a plurality of intermediate elements, each with three rolling elements 17, 18, 19 arranged in series in the drive, are provided between the toroidal running surfaces. As can be seen schematically on the basis of FIGS. 3a to 3c, the rolling elements can either be in a common cage 15c (FIG. 3a) or also in several cages, for example in a cage 15d (FIG. 3a) comprising two rolling elements, or also be arranged in a cage 15e (FIG. 3b) in such a way that one of the rolling elements 18e can be changed in position relative to the other two rolling elements 17e, 19e — optionally stored in its own cage — and thus the preload can be adjusted. This is also shown by way of example in FIG. 2a, where in one of the intermediate links one of the rolling elements 18 is displaced (stiffed) against the other two rolling elements into position 18 ". To change the transmission ratios, the rolling elements can be moved, for example, to 17 ', 18 ', 19' marked position (Fig. 2b). This provides a wide range of variation with regard to the pivoting and / or displaceability of the friction-transmitting rolling elements, and thus possibilities for changing the gear ratios, as well as optional, automatic generation of the preload. The disks - drive disk (s) 1c (1d) and driven disk 2c, (2d) - turn in opposite directions here.

3a to 3c show - for the sake of clarity - the treads, the drive surface and the driven surface 70c, 71c, on shafts 1c ¹ , 2c '; the situation is basically analogous to that with a concavely curved tread. The situation is also comparable for flat treads (stiched). The - always rolling - movement of the rolling elements depending on the arrangement in the cages according to FIGS. 3a to 3c opens up the possibility of generating the preload by pivoting two rolling elements 18d, 19d with their cage 15d (FIG. 3a), the different Exercise or pivoting a rolling element 18e (Fig.3b) and the joint pivoting of all three rolling elements 17c, 18c, 19c in the common cage 15c (Fig.3c). The pivoting and / or The displacement of the cage to generate the preload depends on the friction cones and the force relationships, as well as the type of cage holder. In principle, the pivoting or displacement is possible with any number of rolling elements.

In Fig.2b - analogous to Fig. 1 - a duplication of an arrangement according to Fig.2a is shown. A driven pulley 2d is rotatably mounted on a shaft 5 between two drive pulleys 1c, 1d. Drive disks 1c, 1d and driven disk 2d have curved running surfaces 70c, 70d, 71d, 71d ', each forming a toroid in this way. Intermediate members, each with three rolling elements 17, 18, 19, non-positively transmit the torques of drive disks 1c, 1d to the driven disk 2d. In order to change the transmission ratios, the rolling elements are rotated radially, for example into the position 17 ', 18', 19 'indicated by the broken line, and they roll on the torus surface, so that the adjustment is possible even when the load is present without increased, friction-related wear. The linear arrangement of the rolling elements shown in FIGS. 2a and 2b is purely exemplary, the rolling elements can also be offset from one another or arranged in an "arc" shape.

The necessary pretension can - in a known manner - also be generated by applying pressure to the two outer disks, here 1c and 1d, for example via spring force, hydraulically or else in the manner of the device described in CH-A-157736. The pressure to be applied is dependent on the radial position of the rolling elements, since only in a position parallel to the shaft axis - corresponding to a transmission ratio of 1: 1 - does the contact pressure correspond to this pressure applied from the outside. The preload can also be preset when installing the washers.

In the further exemplary embodiment shown schematically in FIGS. 4 and 5, a drive pulley 1f and an attached driven disc 2f parallel to each other, but with offset axes 3, 4 arranged on rotatably mounted shafts 5f, 6f. Between the drive surface 70f of the drive pulley 1f and the driven surface 71f of the driven pulley 2f, two spherical rolling elements 7f, 8f are arranged in series. The rotational movement of the drive pulley 1f is transmitted to the driven pulley 2f via the three friction points 9, 10, 11. The rolling elements 7f, 8f are arranged in a common cage 15f, which can also be designed as a ball-bearing plate. The connecting lines 60, 61, 62, 63, which connect the friction points 9, 10, 11, of the respective rolling element 7f, 8f with the center 13, 14 of the rolling element 7f, 8f, each include angles 12, 17 which differ from 180 °. One could also say that an imaginary connecting line between the friction points 9, 10, 11 of a rolling element 7f, 8f does not lead through the center point 13, 14 of this rolling element 7f, 8f. The sum of the diameters of the two rolling elements 7f, 8f is therefore greater than the distance between the disks 1f, 2f. The cage 15f is pivotally mounted about an axis 19 which is perpendicular to the connecting lines 60, 61, 62, 63 between the friction points 9, 10, 11 of the rolling elements 7f, 8f and the center points 13, 14 of the rolling elements 7f, 8f.

4 and 5 m driven in the direction of arrow 18, whereby a torque load is present between the disks 1f, 2f, the cage 15f is pivoted by the rolling elements 7f, 8f about its axis 19m arrow direction 16, whereby wedge the rolling elements 7f, 8f between the discs 1f, 2f until the necessary contact pressures have been reached and the movement of the drive disc 1f is transmitted to the driven disc 2f with a ratio dependent on the radial position of the rolling elements 7f, 8f. When the torque load between the disks ends or reverses, for example when the rotation of the drive disk slows down, the pivoting of the cage 15f is reset by the rolling elements 7f, 8f and the driven disk 2f can run freely. The maximum possible torque transmission can be limited by a stop which limits the maximum pivoting of the cage 15f m in the direction of the arrow 16.

The transmission ratio is changed by adjusting the radial position of the rolling elements, for which purpose the cage 15f is displaced along the axis 19. The rolling elements 7f, 8f can roll on each other and on the running surfaces of the disks 1f, 2f, so that an adjustment of the transmission ratio without having to overcome high friction is possible even when the load is applied and the disks are at a standstill.

As can be seen from this, the cage is mounted so as to be pivotable about a swivel axis, which is perpendicular to the connecting lines between the friction points of the rolling elements and the center points of the rolling elements. The necessary contact pressures are generated by pivoting the cage about its pivot axis, which takes place automatically when the gear is driven.

In the case of infinitely adjustable, known gearboxes, as mentioned in the introduction, there was a restriction that the radial position of the rolling elements can only be adjusted with high friction and unbearable material wear or without torque loading on the drive shaft. In the friction gearboxes according to FIGS. 2a, 2b, 4, 5, 6, 7, and 8a to 8c, the spherical rolling elements connected in series can simply roll against one another and on the running surfaces during radial adjustment.

In the exemplary embodiment shown in FIGS. 6 and 7, three drive disks 20, 21, 22 are arranged on a common drive shaft 5. First driven disks 25 and 25 ′ protrude into the space 23 enclosed by the first and second drive disks 20, 21 and m the space 24 between the drive disks 21, 22 further driven disks 26, 26 ′. Two of these driven disks each 25, 25 'and 26, 26' are arranged on a common shaft 6, 6 '. First and second rolling elements 7g, 8g are provided between the drive disks 20, 21, 22 and the driven disks 25, 25 ', 26 and 26', which, analogously to the exemplary embodiment shown in FIGS. 4 and 5, are each not shown here Cages are arranged.

The connecting lines between the friction points and the center of the respective rolling element close angles other than 180 °

The inclinations of the connecting lines between the centers of the rolling elements relative to the axes 3, 4 and 4 'are opposite, so that when the drive m is one of the two directions of rotation the two pairs of rolling elements wedge, which act on a driven disk from both sides. In the example in FIG. 7, the two pairs of rolling elements on the left are responsible for a direction of rotation, for example a clockwise rotation, the two pairs of rolling elements on the right for a rotation m in the opposite direction, for example to the left. Of course, this is only the case if the angular arrangement is carried out in a manner corresponding to FIG. 7. In the embodiment according to FIGS. 6 and 7, two driven disks are provided for each of the two directions of rotation, wherein different ratios can be set for the two directions of rotation.

The axial forces caused by the contact pressure do not have to be absorbed by bearings, but are transmitted directly to the shaft 5. This reduces wear and reduces bearing friction.

In this way, it could also be provided to transmit the drive only in one direction of rotation and to provide a freewheel in the other direction of rotation. Two drive disks and an intermediate driven disk would suffice for this. But there could also be other driven disks and associated drive pulleys can be connected in parallel, specifically when transmitting the movement in one direction as well as in both directions.

In the exemplary embodiment of the invention shown in FIGS. 8a, 8b and 8c, an angular gear is created by transmitting the movement from a drive pulley 1ι to a driven shaft 42, which is rotatably supported about its axis 44, via the rolling elements 7ι, 8ι. Translation and direction of rotation of the shaft 42 can be changed by the displacement of the cage 7ι, 8ι holding cage (not shown) m arrow direction 45.

As can be seen more clearly from FIG. 8c, the connecting lines 60, 61; 62, 63 between the friction points 9, 10, 11 and the center points 13, 14 of the rolling elements 7ι, 8ι in turn from 180 ° angles 12, 17. As a result of this and due to the pivotability of the cage holding the rolling elements 7ι, 8ι, the necessary contact pressures can be generated automatically.

As can be easily seen, the designations "Antπebs" disk and "driven" disk in the above figures are essentially interchangeable, so for example in FIGS. 6 and 7 the drive disks can be located between the driven disks as well, for example in FIG .8a to 8c could be the shaft drive means and the pulley drive means.

Claims

PATENT CLAIMS

1. Friction gear with at least one drive surface

(70c, 70d) and at least one driven surface (71d) with at least one intermediate element in the form of spherical rolling elements (17, 18, 19), characterized in that the drive surface (70c, 70d) and the driven surface (71d) - in particular concave - arched, possibly toroidal, and at least two, in particular three, rolling elements (17, 18, 19) are arranged in series in terms of drive.

2. Friction gear according to claim 1, characterized in that at least two rolling elements (17, 18, 19) are arranged in a common cage (15c, 15d), the cage (15c, 15d) being pivotable for changing the gear ratios.

3. Friction gear according to claim 2, characterized in that the cage (15c, 15d, 15e) is further pivotable or displaceable and / or at least one of the at least two rolling elements (18e) within the cage (15e) positionally variable with respect to the (die) other rolling elements (17e, 19e) for changing the preload.

4. Friction gear according to one of the preceding claims, characterized in that means for adjusting the bias voltage are provided via an externally imposed, defined change in relative distance between the drive surface (70c, 70d) and the driven surface (71d).

5. Friction gear with at least one drive surface (70f) and at least one driven surface (71f), wherein between each drive surface (70f) and the associated driven surface (71 f) in each case at least one intermediate member in the form of at least two drives arranged in series , spherical rolling elements (7f, 8f) is provided, characterized in that the rolling elements (7f, 8f)

- Slidable or pivotable, and slidable or are pivotable, thus setting the gear ratios and the preload.

6. Friction gear according to claim 5, characterized in that the at least two rolling elements (7f, 8f) are arranged within an adjustable, common cage (15f).

7. Friction gear according to claim 6, characterized in that the optionally pivotable cage (15f) can also be moved under load, optionally along its pivot axis.

8. Friction gear according to one of the preceding claims, characterized in that at least two drive disks (20, 21, 22) arranged on a common drive shaft (5) open up an intermediate space (23, 24), in each of which at least one driven disk

(25, 26) is arranged, at least one intermediate member being provided between the drive disks (20, 21, 22) and the at least one driven disk (25, 26).

9. Friction gear according to one of the preceding claims, characterized in that the intermediate member is arranged to create an angular gear between a drive disk (1ι) and a driven shaft (42), or a drive shaft and a driven disk.