GB1603889A

GB1603889A - Change speed transmission

Info

Publication number: GB1603889A
Application number: GB2090478A
Authority: GB
Original assignee: C Van der Lely NV
Current assignee: C Van der Lely NV
Priority date: 1977-08-17
Filing date: 1978-05-19
Publication date: 1981-12-02

Description

(54) IMPROVEMENTS IN OR RELATING TO A CHANGE SPEED TRANSMISSION (71) We, C. VAN DER LELY N.V., of 10, Weverskade, Maasland, The Netherlands, a Dutch Limited Liability Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a change-speed transmission.

According to the present invention there is provided a change-speed transmission comprising an input element, an output element, and first and second members, the first member being rotatable by the input element about a main axis and being pivotable about a pivot axis which is spaced from the main axis and from the centre of gravity of the first member, whereby rotation of the first member about the main axis causes the first member to be biased by centrifugal force outwardly of the main axis about the pivot axis into contact with the second member, one of the first and second members comprising a rotatable body of revolution, the diameter of which varies along its axis, the rotatable body being rotated about its axis upon rotation of the input element by virtue of the contact between the first and second members, the rotatable body being connected to the output element in such a way that rotation of the rotatable body about its axis drives the output element, the region of contact between the rotatable body and the other member being adjustable axially of the rotatable body to vary the transmission ratio between the input and output elements.

For a better understanding of the present invention and to show how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which: Figure 1 is a sectional view of a changespeed transmission; Figure 2 is a sectional view taken on the line II-II in Figure 1; Figure 3 is a sectional view taken on the line 1 1-111 in Figure 1; Figure 4 is a sectional view of another embodiment of a change-speed transmission; and Figure 5 is a sectional view taken on the line V-V in Figure 4.

The change-speed transmission shown in Figures 1 to 3 comprises a housing 1 having an input element or shaft 2, an intermediate or driving shaft 3 and an output element or shaft 4. The intermediate shaft 3 is provided at each end with a respective stub 5 and 7 which are rotatably journalled in corresponding recesses in the adjacent ends of the shafts 2 and 4.

The input shaft 2 has fastened to it by means of splines 8 a sun wheel 7. The teeth at the circumference of the sun wheel 7 are in mesh with the teeth of a number of planet wheels 9, which are rotatable on corresponding shafts 10 journalled in bearings 11 and 12. The bearings 11 are directly supported by the housing 1, and the bearings 12 are supported by a ring 13. The ring 13 is supported on the housing 1 at several places by supports 14, the supports 14 being disposed around the sun wheel 7 and between two neighbouring planet wheels 9. The centrelines of the shafts 10 are parallel to the common centrelines 15 of the shafts 2, 3 and 4. The teeth of the planet wheels 9 away from the sun wheel 7 are in mesh with inner teeth of a ring gear 16 which surrounds the planet wheels 9 and the ring 13 and is fastened by axial splines 17 to the end of the driving shaft 3 nearer the input shaft 2.

On the ring gear 16 is journalled a number (in this embodiment, five) of arms 18.

The arms 18 are freely pivotable with respect to the ring gear 16 about stub shafts 19, the centrelines of which are parallel to the centre-line 15 and are located at a distance from the driving shaft 3. The distance of the centreline of each stub shaft 19 from the centreline 15 is approximately equal to half the radius of the pitch circle of the ring gear 16. Near the end of each arm 18 away from the stub shaft 19 is a bearing 20 which holds a stub shaft 21 of a first member in the form of a doubleconical roller 22. Each of the five rollers 22 has a portion 23 with an outer surface in the form of a truncated cone, the diameter increasing away from the associated arm 18 with the larger diameter being located near a plane of symmetry 24 or the roller 22, which is perpendicular to the centreline 25 of the roller. The centreline 25 coincides with the centreline of the associated stub shaft 21. On the side of the plane of symmetry 24 away from the arm 18 there is a second portion of the roller 22 also having a frustoconical surface, the larger and smaller diameters of which are equal to those of the portion 23, whilst the length of the portion 26, measured along the centreline, is equal to the length of the portion 23. At the end of the portion 26 remote from the arm 18 the roller 22 is provided with a stub shaft 27, having external, axial splines fitting to internal splines in a pinion 28 which meshes with a pinion 29. The pinion 29 is rotatable on a shaft 30, the centreline of which is parallel to the centreline 15 and 25. All of the rollers 22 have an identical structure.

The stub shaft 27 of each roller 22 has a projection on the end facing away from the portion 26 in the form of a stub shaft 31, which is journalled by a bearing 32 in an arm 33. Each arm 33 is freely pivotable about a sleeve 34, which is part of the pinion 29. Each arm 33, together with the pinion 29 and the sleeve 34, is journalled on the shaft 30 by bearings 35 and 36. There are five bearings in all, and each of them is directly secured in a star-shaped carrier 37, which is rigidly secured by splines 38 to the end of the intermediate shaft 3 away from the ring gear 16. At places circumferentially between the pinions 28 the carrier 37 has extensions 39 (Figures 1 and 3), each of which has supports 40, which extend from the associated extension 39 in a direction parallel to the centreline 15 and away from the ring gear 16. To the ends of the supports 40 away from the extensions 39 is fastened a ring 41 which extends radially inwardly towards the output shaft 4, as viewed in cross-section, and which is provided with bearings 36 for the shafts 30, located radially between the centreline 15 and the centrelines 25.

The five pinions, which may be considered to be planet wheels, mesh with a sun wheel 42, which is fastened by splines 43 to the output shaft 4.

In the sectional view of Figure 1 two annular second members or rings 44 and 45 are visible, disposed in the region between the ends of each of the rollers 22, so that the position of these rings is invariably symmetrical about the plane of symmetry 24 or the rollers 22. The outer diameters of the spaced rings 44 and 45 are slightly smaller than the inner diameter of the housing 1 at their positions, whereas the inner size of the rings 44 and 45 is such that the rollers 22 fit at least partly inside the space bounded by the rings. The sum of the distance between the centreline 15 of the shaft 3 and that of a stub shaft 19 and of the distance between the centreline of the stub shaft 19 and the centreline 25 is greater than the inner size of the rings 44 and 45. The rings 44 and 45 can be moved symmetrically towards and away from the plane of symmetry 24.

For this purpose the two rings are adjustably supported by means of four screw spindles 46 equally spaced apart around the circumference of the housing 1, each of these spindles passing through internally screwthreaded holes in the rings 44 and 45.

These tapped holes are located near the outer circumference of the rings 44 and 45 in the region radially outside the rollers 22.

The internal screwthread of the holes cooperates with the screwthread on the outer surface of the associated screw spindle 46, which has two screwthreaded portions of opposite hand (Figure 1), the separation area between the two portions coinciding with the plane of symmetry of the rollers 22. Each screw spindle 46 is supported by supports 47 and 48 which are rigidly secured to the housing 1. One of the screw spindles 46 is extended to provide a shaft 49 which projects out of the housing 1 and is provided at its end with a device for turning the screw spindle. The shaft 49 of this screw spindle 46 has axial splines 50 disposed at one side of the support 48 and these splines fit in internal splines in a pinion 51 which is positioned on the shaft 49 and is held by a sleeve 52 at a distance from the wall of the housing 1. The pinion 51 meshes with internal teeth of a ring 53, the outer circumference of which is in full contact with the inner surface of the housing 1, which is cylindrical at that region, so that the ring 53 is rotatable with respect to the housing 1. The ring 53 bears by its outer circumference in a bore formed in the housing 1 and is held in place axially by a sleeve 54.

The inner surfaces of the two rings 44 and 45 are each part of an imaginary conical surface having a cone angle equal to the cone angle of the conical surfaces of the portions 23 and 26 of the rollers 22. These inner surfaces are slightly convex.

When during operation the input shaft 2 is driven by a prime mover the sun wheel 7 will drive the planet wheels 9 about the shafts 10, the axes of which, in this embodiment, remain stationary with respect to the housing 1. The planet wheels 9 drive the ring gear 16 and hence also the intermediate shaft 3. The planetary gear transmission 7, 9, 16 in this embodiment drives the inter mediate shaft 3, with a given input speed of the shaft 2, at a pseed which is desirable for structural reasons. With the dimensions shown the intermediate shaft 3 will be driven with a speed of 1400 revlmin with an input speed of 2000 rev/min. It will be appreciated that it is possible to drive the intermediate shaft 3 directly.

As a result of the speed of the driving shaft 3 the conical rollers or first members 22, which are freely pivotable on their arms 18 and 33 on the ring gear 16 and the carrier 37 respectively, are flung radially outwardly by centrifugal force into engagement with the inner surfaces of the rings 44 and 45. By suitably selecting the speed of the intermediate shaft 3, the mass of the rollers 22, and the distance of the centrelines 25 from the centreline 15, the pressure between the smooth outer surface of each roller 22 and the inner smooth surfaces of the rings 44 and 45 can be made such that the rollers run without slipping on the inner surfaces of the stationary rings 44 and 45.

If desired, these surfaces may be provided with friction material to impart a certain amount of roughness to said surfaces in order to enhance the frictional contact.

The rollers 22, pressed against the rings 44 and 45 drive, by means of the pinions 28 fastened to the rollers, the planet wheels 29 fastened to the carrier 37, the sun wheel 42 and hence the output shaft 4. The carrier 37 has the same speed as the intermediate shaft 3, since it is rigidly secured to the intermediate shaft.

In the position shown in Figure 1 the rings 44 and 45 are in contact with the smaller diameter regions of the two conical surfaces 23 and 26 of the rollers 22 so that a comparatively high number of revolutions of the rollers 22 and hence also of the output shaft is obtained. By turning the shaft 49, the associated screw spindle 46 and the three other screw spindles 46 are turned in an analogous manner by means of the pinions 51 and the ring wheel 53 so that the two rings 44 and 45 servir, as reactive surfaces are moved towards one another and towards the plane of symmetry 24 of the rollers 22 by means of the left-hand and right-hand screwthreads on the screw spindles 46. The centre lines 25 of the rollers 22 are thus forced radially inwardly into a position in which the distance between the centrelines 25 and the centreline 15 is smaller. This happens because, during the adjustment of the second members 44 and 45, an increasing diameter of the portions 23 and 26 of the rollers 22 comes into contact with the rings. During this displacement the speed of the rollers decreases so that the output shaft 4 is also driven with a continuously decreasing speed through the planetary gear transmission 28, 29, and 42.

With the proportioning shown and with a speed of 1400 rev/min of the intermediate shaft 3, the output speed of the shaft 4 can be varied between 3000 and 200 rev/min so that a ratio of speed variation of 15:1 is obtained. This change-speed gear is suitable for transmitting a power of about 200 HP. The double-conical rollers shown in the Figures have a ratio between the larger and the smaller Aiameters of about 1.75, but it will be obvious that this ratio may be chosen otherwise. The rollers need not have conical surfaces; differently shaped bodies of revolution may be employed, depending upon the intended use of the change-speed gear. Also, as viewed in a direction perpendicular to the rotary axes of the rollers (Figure 1), the rollers need not have straight surfaces but may be curved lines. As stated above the intermediate shaft 3 may be driven directly by the prime mover.

In the second embodiment, shown in Figures 4 and 5, a housing 55 supports an input shaft 56 and an output shaft 57, the end of the shaft 56 facing the shaft 57 being provided with a spigot 58, which is journalled in a bore in the end face of the shaft 57. The shaft 56 is journalled in the housing 55 in bearings 59 and 60, near the region where the shaft 56 enters the housing 55, and in a bearing 61 located at a distance from the bearing 60 and arranged in a partition 62 of the housing 55. The output shaft 57 is journalled near the spigot 58 in a bearing 63 and in a bearing 64 which is spaced from the bearing 63 and is located near the region where the shaft S7 passes out of the housing 55. The shafts 56 and 57 have a common centreline 65.

The bearing 61 does not support the shaft 56 directly but instead supports a sliding sleeve 66 which surrounds the shaft 56.

The sleeve 66 is axially displaceable but not rotatable with respect to the shaft 56. To this end, the sleeve 66 has internal splines which engage external splines on part of the shaft 56.

The sleeve 66 isrovided, at the end facing the output shaft 57, with a flange 67 which is perpendicular to the centreline 65.

Near the circumference of the flange 67 there is a number, in this embodiment, four of pivotal shafts 68 which extend from the flange 67 towards the output shaft 57 and which lie parallel to the centreline 65. On each of the pivotal shafts 68 is pivotably mounted first member comprising a driving friction element 69. Each of the four friction elements 69 in this embodiment has a part-cylindrical outer surface. When they are in a position in which they join each other, the four friction elements 69 make up a cylindrical surface in contrast to the roller 22 of the first embodiment. With respect to the direction of rotation A (Figure 5) each friction element 69 trails with respect to its pivotal shaft 68. Near its pivotal shaft 68 each friction element 69 has a stop surface 70, which is inclined outwardly and rearwardly with respect to the direction of rotation A. The adjacent friction element 69 has a corresponding stop surface 71, which is located, in the driven state, at a short distance from the stop surface 70. In the view of Figure 5, a line connecting the point of transition between the outer surface of each friction element 69 and its stop surface 70, and the centreline of the associated pivotal shaft 68 is at an obtuse angle to a tangent to the outer surface at the point of transition this angle opening towards the next-following pivotal shaft 68, viewed in the direction of rotation A. The four friction elements 69 together constitute a cylindrical driving body 72.

During operation the driving body 72 is in contact with second members comprising six conical rollers 73. Each roller 73 is rotatably journalled on a shaft 74. The centrelines 75 of the shafts 74 are located on an imaginary conical surface and intersect the centreline 65 at a point located, in this embodiment, near the bearing 59 and outside the housing 55. The cone angle of this conical surface is equal to the cone angle of the conical outer surfaces of the conical rollers 73. From Figure 4 it will be apparent that each friction element 69 is in contact with at least one of the conical rollers 73 along a generatrix of that roller 73 which extends parallel to the centreline 65. The smaller diameter of each of the rollers 73 is, at least in this embodiment, located at the end of the roller which faces the input 56.

The shafts 74 of the rollers 73 are journalled in bearings 76 arranged in the partition 62 and in bearings 77 arranged in a rear wall of the housing 55. The rollers 73 are non-rotatably fastened to their shafts 74. Also non-rotatably fastened to these shafts 74 are bevel gear wheels 78, which mesh with bevel gear wheels 79 rotatably mounted on shafts 80, which are held in bearings 81 in the rear wall of the housing 55. The gear wheels 79 are all in mesh with a gear wheel 82, which is fastened by splines to the output shaft 57.

Where the driving body 72 is positioned on the shaft 56 there is a ring 83 having fastening points for four tension springs 84, whose ends away from the ring 83 are secured to respective ones of the friction elements 69 at a point lying at a distance from the associated pivotal shaft 68. These tension springs tend to urge the stop surfaces 70 and 71 into contact with one another.

The housing 55 is provided with slots 85 through which a lever 86 is introduced into the housing 55, this lever being actuated from outside the housing 55. The lever 86 has a fork-like end portion 87, which is connected with the end of the sleeve 66 remote from the member 72 for limited pivotal movement. The lever 86 is pivotable about a pivotal shaft 88 located outside the housing and is fixable in a plurality of positions.

During operation the input shaft 56 is driven by a prime mover in the direction of rotation A, whilst the sleeve 66 is set with respect to the shaft in the position shown in Figures 4 and 5 by means of the lever 86.

The friction elements 69 will then turn about their pivotal shafts 68 and as a result of the centrifugal force exerted on their mass, and they tend to turn outwardly against the springs 84, if these springs are employed.

These friction elements can turn outwardly only through a very small angle, since after only a slight turn they engage the six rollers 73. By suitably selecting the mass of the friction elements 69, the radius of the cylindrical body 72 and the speed of the input shaft 56, the contact pressure between the elements 69 and the rollers 73 can be such that the elements 69 cause the rollers 83 to rotate without slip. The rotation of the rollers 73 is transferred via the gear wheels 78, 79 to the central gear wheel 82 and hence to the output shaft 57. When the sleeve 66 is moved in the direction B (Figure 4) by the lever 86, the smooth outer surface of the cylindrical body 72 comes into contact with parts of the roller 73 having a larger radius so that the speed of the output shaft 57 can be continuously varied by actuating the lever 86.

In contrast to the first embodiment, cylindrical driving members are used herein, which come, during operation, into contact under a comparatively high pressure with rollers which rotate during operation, whereas in the first embodiment the driving members roll along stationary second members. When the springs 84 are used, the friction elements 69 are slightly withdrawn from the rollers 73 when the input shaft 56 is not driven or is rotated only at low speed, so that the input shaft 56 can be freely rotated with respect to the output shaft 57, This is possible owing to the above-mentioned disposition of each pivotal shaft 68 with respect to the boundaries of the associated friction element and to the clearance between the stop surfaces 70 and 71 during operation. The surfaces of the members 69 and 73 may, as in the first embodiment, consist of hard steel, but they may, as an alternative, be coated with a frictional material.

The two embodiments illustrate constructions in which it ls possible to obtain in a very simple manner an infinity variable transmission based on a slip-free friction drive obtained under the action of a comparatively high pressure between two members with the use of centrifugal force.

These change-speed gears may be employed in the drive of a vehicle, for example, a motorcar, a motor-truck or a tractor and may be used for transferring the comparatively high powers of such vehicles of the order of about 200 HP.

WHAT WE CLAIM IS: 1. A change speed transmission comprising an input element, an output element, and first and second members, the first member being rotatable by the input element about a main axis and being pivotable about a pivot axis which is spaced from the main axis and from the centre of gravity of the first member, whereby rotation of the first member about the main axis causes the first member to be biased by centrifugal force outwardly of the main axis about the pivot axis into contact with the second member, one of the first and second members comprising a rotatable body of revolution, the diameter of which varies along its axis, the rotatable body being rotated about its axis upon rotation of the input element by virtue of the contact between the first and second members, the rotatable body being connected to the output element in such a way that rotation of the rotatable body about its axis drives the output element, the region of contact between the rotatable body and the other member being adjustable axially of the rotatable body to vary the transmission ratio between the input and output elements.

2. A change-speed transmission as claimed in claim 1, in which, in operation, the rotary body runs along a surface of the other member.

3. A change-speed transmission as claimed in any one of the preceding claims, in which a housing is provided and in which the second member is fixed against rotation about the main axis with respect to the housing.

4. A change-speed transmission as claimed in any one of the preceding claims, in which at least part of the surface of the rotatable body is conical.

5. A change-speed transmission as claimed in any one of the preceding claims, in which the first member is mounted for free pivotal movement about the pivot axis.

6. A change-speed transmission as claimed in any one of the preceding claims, in which the first member is mounted on an arm which is pivotable about the pivot axis.

7. A change-speed transmission as claimed in any one of the preceding claims, in which the rotatable body comprises at least two portions which are disposed symmetrically to one another.

8. A change-speed transmission as claimed in any one of the preceding claims, in which the member other than the rotatable body comprises a ring which is displaceable axially with respect to the main axis.

9. A change-speed transmission as claimed in claim 8, in which the rotary body engages the inner surface of the ring.

10. A change-speed transmission as claimed in claim 8 or 9, in which the inner surface of the ring is generally conical.

11. A change-speed transmission as claimed in any one of claims 8 to 10, in which the ring is displaceably supported on at least one screwthreaded spindle.

12. A change-speed transmission as claimed in claim 11, in which the ring is supported by a plurality of screwthreaded spindles which are coupled with one another.

13. A change-speed transmission as claimed in any one of claims 8 to 12 when appendant to claim 6, in which the ring is one of two rings of the said other member, each of which rings co-operates with a respective one of the two portions of the first member, the two rings being displaceable together in opposite directions.

14. A change-speed transmission as claimed in claim 13 when appendant to claim 11 or 12, in which the or each screwthreaded spindle has two screwthreads of opposite hand.

15. A change-speed transmission as claimed in any one of claims 8 to 14, in which the axis of the or each ring is parallel to the axis of the rotatable body.

16. A change-speed transmission as claimed in any one of the preceding claims, in which the first member comprises the rotatable body.

17. A change-speed transmission as claimed in any one of the preceding claims, in which the first member is connected to be driven by the input element through a planetary gear transmission.

18. A change-speed transmission as claimed in any one of the preceding claims, in which the rotatable body is connected to drive the output element through a planetary gear transmission.

19. A change-speed transmission as claimed in claim 18, in which the planetary gear transmission includes a planet carrier which is connected to be driven by the input element.

20. A change-speed transmission as claimed in any one of claims 1 to 4, in which the member other than the rotatable body comprises a ring, the axis of which is inclined to the axis of the rotatable body.

21. A change-speed transmission as

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. very simple manner an infinity variable transmission based on a slip-free friction drive obtained under the action of a comparatively high pressure between two members with the use of centrifugal force. These change-speed gears may be employed in the drive of a vehicle, for example, a motorcar, a motor-truck or a tractor and may be used for transferring the comparatively high powers of such vehicles of the order of about 200 HP. WHAT WE CLAIM IS:

1. A change speed transmission comprising an input element, an output element, and first and second members, the first member being rotatable by the input element about a main axis and being pivotable about a pivot axis which is spaced from the main axis and from the centre of gravity of the first member, whereby rotation of the first member about the main axis causes the first member to be biased by centrifugal force outwardly of the main axis about the pivot axis into contact with the second member, one of the first and second members comprising a rotatable body of revolution, the diameter of which varies along its axis, the rotatable body being rotated about its axis upon rotation of the input element by virtue of the contact between the first and second members, the rotatable body being connected to the output element in such a way that rotation of the rotatable body about its axis drives the output element, the region of contact between the rotatable body and the other member being adjustable axially of the rotatable body to vary the transmission ratio between the input and output elements.

21. A change-speed transmission as

claimed in claim 20, in which the axis of the ring intersects the axis of the rotatable body.

22. A change-speed transmission as claimed in any one of the preceding claims, in which the first member is one of a plurality of similar part-cylindrical mem bers which together provide a substantially cylindrical surface.

23. A change-speed transmission as claimed in any one of claims 20 to 22, in which the second member comprises the rotatable body.

24. A change-speed transmission substantially as described herein with reference to and as illustrated in the accompanying drawings.

25. A vehicle comprising a change-speed transmission as claimed in any one of the preceding claims.