DE2807971A1 - Steplessly-adjustable friction drive - has intermediate discs formed with curved peripheral profile and main discs slidable on shaft - Google Patents

Abstract

The steplessly adjustable friction drive unit is particularly for motor vehicles, having coaxial driving and driven discs, each with a concave peripheral face, against which intermediate friction discs run. The latter have shorter peripheral faces and rotate on brackets tilting in the housing on axes crossing and clear of the unit axis so as to vary the ratio. The discs are pressed against the driving and driven ones. The intermediate discs have a peripheral profile which is curved in cross-section. The mating faces of the driving and driven discs are so shaped that in each position of the intermediate discs, the point of intersection of all disc axes is likewise that of the tangents at all contact points between discs.

Description

Infinitely adjustable friction disc control gear,

especially for motor vehicles The invention relates to a friction disc variable speed transmission, in particular for motor vehicles, according to the preamble of the preceding claim 1. This transmission is primarily I; never intended for use in motor vehicles, and then naturally additional organs, such as z.P. a starting clutch and a rear-mounted gearbox to reverse the direction of rotation (reverse gear).

Transmission of the type mentioned above are z. Bo by the German Auslegeschrift 1 625 119 known. Common to all received versions is that along their translation changes, they often have none at all, or at most two Have rolling positions in which the rolling conditions are geometrically ideal, d. H. could be wetted by a toothing. All other rolling positions are subject to forced slip, which is referred to as drilling friction and which leads to Loss of performance or loss of efficiency leads.

The object of the invention is to create a transmission that in each Generating position (i.e. in every gear ratio) without drilling friction d. H. so without forced slip works, so that higher gear efficiency and lower thermal loads the contact points can be reached. This task is specified for the gearboxes Type solved by the characterizing features of claim 1 above.

This solution has the advantage that in every position the intermediate disk geometrically ideal rolling conditions prevail. So that will the power transmission free of Drilling friction and it can therefore Avoid loss of performance. The efficiency of such a transmission is also better. The invention therefore has the geometric shape of the contour General thoughts on the content1 that a rolling contour has a circular cross-section, and the other is then obtained therefrom according to the doctrine given.

I. E. in other words, one can make the above assignment also reverse the contours to the slices.

Since there is always a basic contact pressure at the rolling points of the disks must be, it is known to have one or two disks over the above-mentioned arrangement according to DAS 1 625 119 z. B. the washer - to act resiliently d. H. the The disc or discs in question are not rigidly attached to the shafts. this but does not represent axial mobility within the meaning of the invention, namely in which larger paths are provided for the drive and driven pulley. One can too for this purpose after the invention z. B. provide a roller bearing in the spline shaft.

The carriers of the intermediate discs are used for the purpose of gear ratio adjustment pivoted together, expediently according to the features of the preceding claims 2 and 3. In principle, the drum can also be hit by a double-acting Ring piston take place. The trunnions themselves are mounted in blocks that immediately or are received in the housing by means of a common iting. Also can Springs be on so that all spacers are evenly on the two rest on other disks and thus the load is evenly distributed.

In order to have a corresponding support on the drive or driven pulley To achieve the axial force, the training is expediently based on the features of claims 4 and 5. To generate the basic pressure, disc springs are used preferred. As a result of the change in torque in the various gear ratios training according to the Features of claim 6 useful. Included can determine both drive and output torque through special sensing elements and be given to appropriate control organs, but in principle it could also do that Drive torque derived from the drive motor and the output torque accordingly the translation can be determined. Other combinations are also conceivable. According to the invention a design according to the features of claim 7 is advantageous.

Details of the invention are shown in the exemplary embodiment in the drawing based on a longitudinal section (partially) through a corresponding gear.

According to the drawing; is at the bottom of the two-part gear housing (10) a circuit board (11) flanged which contains the control elements. In the gearbox (10) the drive shaft (12) and the output shaft (13) are coaxial on tapered roller bearings (14) or a similar bearing, is located on both shafts so that it cannot rotate and one pressure cylinder (15) each, axially immovable. This cylinder is on a drive pulley (17) accommodated on the drive side in a sealing and axially movable manner, which are connected to the drive shaft (12) in a longitudinally movable manner by means of a spline is. The corresponding arrangement can be found on the abortion side, by there in the driven pulley (18) is arranged in exactly the same way.

Disk springs (19) are arranged in the two cylinders (15) through soft the two discs (17 and 18) biased towards each other are. Both discs have the same concave contours (20), their shape later will be written even more precisely.

There are in rolling engagement with the two disks (17) and (18) two or three washers (21), each in a manner not shown and way on a carrier (22) are rotatably mounted. Any porter is pivotable about a bolt (23), the axis of this bolt (23) being the gear axis (24) crosses at right angles at a distance.

Each bolt (23) is received in a bracket (25) and all Lugs are mounted in the housing $ (10) by means of a common ring (26) The contour (27) of the intermediate disks has a circular cross-section. The axes of rotation (28) of all intermediate disks intersect the axis of rotation (24) of the other two Disks (17) and (18), d. H. the gear axis (24) always in a point 3, the when the intermediate disks (21) are pivoted on the gear shaft (24). The exact contour of the other two disks (17) and (18) is now obtained by that in all positions of the washers (21) this point 3 is also the point of intersection the surface lines (29), d. H. represents the tangents nn the pitch points @.

With this geometric shape, there is no forced slip to the Pitch points W niif. d. H. the discs roll on each other in an ideal way.

The supports (22) for the intermediate disks (21) grip with ball studs (30) in a drum part (? 1) with an annular piston (36) at both ends These ring pistons are arranged in corresponding pressure cylinders (33) and hydraulically actuated. Only in this way can all carriers of the intermediate discs (21) pivoted together about their bolts (23) and thus the transmission ratio to be changed. For the pressure medium supply this swivel mechanism is with the drive shaft (12) is connected to an oil pump (34). This delivers over the lines f the pressure in the circuit board (11) and in particular in the not shown Organs of attitude control (36). From there, depending on the desired gear ratio preferably automatically the oil pressure via the lines (37) to the respective pressure cylinders (33) forwarded.

At the two disks (17 and 18) occurs depending on the translation, i. H. thus, depending on the torque to be transmitted, a different size axial thrust. This is absorbed by a corresponding pressure in the cylinders (15). The pump pressure is converted into a torque-dependent control (38) in the circuit board a corresponding pressure is generated and via the lines (39) and the corresponding radial or axial bores (40) and (41) in the drive or output shaft the relevant cylinders (15) supplied. This way it becomes a completely even Contact pressure at the rolling points W generated or maintained.

Claims (7)

Infinitely adjustable friction disc variable speed transmission, especially for Motor vehicles A n s p r ü c h e 1. Infinitely adjustable friction disc control gear, especially for motor vehicles, with coaxial drive and output pulleys with a concave jacket profile and with intermediate friction disks rolling on it, which have a shorter jacket profile and which are rotatably mounted on carriers, which in turn, the gear axis at a distance crossing axes, pivotable in Housing are arranged non-rotatably opposite this, wherein means for pivoting the carrier for the purpose of changing the gear ratio and means for generating a pressing force are provided on the casing profiles of drive, output and intermediate disks, d a d u r c h e k e n n n z e i c h n e t that the intermediate washers (21) are in Have cross-section circular jacket profile that the jacket profile of the drive and Output pulley (17 and 18) is designed so that in every position of the intermediate disks (21) the point of intersection (S) of the axes of rotation of all disks at the same time the point of intersection of the surface lines (tangents) at the rolling points (W) and that drive and Output pulley (17 and i8) with their shafts (12 and 13) non-rotatably but axially displaceable are connected. 2. Transmission according to claim 1, d a d u r c h g e k e n n -z e i c h n e t, then the carriers (22) of the intermediate disks (21) on their the intermediate disks opposite ends are provided with ball studs (30), which are axially displaceable in an Engage drum (31) which at both sides with one pressurized medium each Annular piston (32) is provided. 3. Transmission according to claim 2, d a d u r c h g e k e n n -z e i c h n e t that the pressure medium is applied automatically by a hydraulic position control he follows. 4. Transmission according to one or more of claims 1-3 d a d u r c h s e k e k e n n n z e i n e t, then the drive pulley (17) and the driven pulley (18) designed as a pressure medium-actuated piston and in corresponding pressure cylinders (15) are arranged axially movable on the relevant shafts (12 and 13) are rotationally fixed and axially immovable. 5. Transmission according to claim 4, d a d u r c h g e k e n n -z e i c h n e t that in the cylinders (15) for the drive and driven pulley spring (13) are arranged to generate a basic contact pressure. 6. Transmission according to claim 4 and, d a d u r c h g e k e n n z e i c h n e t that the drive pulley and the driven pulley through one in the relevant Pressure cylinder introduced, torque-proportional controlled pressure medium can be acted upon are. 7. Transmission according to one or more of claims 1 - 6 d a d u r c h g e k e n n n z e i c h n e t that with the drive shaft (12) a pressure medium pump (3i) for the pressure medium supply is in driving connection and that control organs (36) and 38) are provided to derive the pressure for the gear ratio control on the one hand and for the torque-dependent deactivation of the drive and driven pulley on the other hand.