GB1603918A

GB1603918A - Chain for a chain transmission

Info

Publication number: GB1603918A
Application number: GB2524778A
Authority: GB
Original assignee: C Van der Lely NV
Current assignee: C Van der Lely NV
Priority date: 1977-06-29
Filing date: 1978-05-31
Publication date: 1981-12-02

Description

(54) A CHAIN FOR A CHAIN 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 chain for a chain transmission.

According to the present invention there is provided a chain for a chain transmission, comprising linked friction members each of which has two friction surfaces disposed on opposite sides of the friction member, each friction member comprising two friction elements each having a respective one of the friction surfaces of the friction member, the friction elements being movable relatively to each other to alter the relative positions of the friction surfaces.

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 side elevation of a changespeed mechanism; Figure 2 is an elevational view taken on the line II-II in Figure 1; Figure 3 is a sectional view taken on the line III-III in Figure 2; Figure 4 is a side elevation of part of a chain of the transmission taken in a direction corresponding to the elevational view of Figure 2; Figure 5 is a section view taken on the line V-V in Figure 4, and Figure 6 is an elevational view of part of the chain in the direction of the arrows VI-VI in Figure 4.

The change-speed transmission shown in the drfawings comprises a housing 1 and an input shaft 2, which can drive an input pulley 4 through a pinion transmission 3. The flanges of the pulley 4 are axially displaceable relative to one another by means of an adjusting mechanism 5. The pulley 4 is drivably connected by a chain 6 with an output pulley 7. The flanges of the pulley 7 are axially displaceable relatively to one another by means of an adjusting mechanism 8, which is coupled through a control system with the adjusting mechanism 5. The driven output pulley 7 is keyed to a shaft 10, driving a reversing gear arrangement 9 (Figures 1 and 2).

The input shaft 2 is provided with a bevel pinion 11, which is in engagement with a bevel pinion 12 fastened to the end of a shaft 13, on which the pulley 4 is coaxially arranged. As shown in Figure 3, a pressure ring 14 is keyed to the shaft 13 on one side of the pulley 4. On the same side as the pressure ring 14 the shaft 13 carries a flange 15 which has a diameter about double that of the pressure ring 14. The flange 15 com- prises a flange portion 16, which extends generally radially about a sleeve portion 17, which is integral with the flange portion 16.

The sleeve portion 17 locates the flange 15 on the shaft 13 and extends to one side of the radially extending flange portion 16.

The flange portion 16 is provided on its surface 18 facing away from the pressure ring 14 with a flange portion 19, which is fastened by a number of bolts 20 to the flange portion 16. The surface 21 of the flange 15 facing away from the flange portion 16 forms part of an imaginary conical surface having a cone angle of about 170q the cone being coaxial with the shaft 13. The flange portion 19 has an annular shape and its side facing the pressure ring 14 is in full contact with the surface 18 of the flange portion 16; this surface 18 is perpendicular to the centre line 22 of the shaft 13. The circular inner face of the flange portion 19 is a close fit over the outer surface of the sleeve portion 17.

Around the sleeve portion 17 is journalled an adjustable flange 23 of the pulley 4, the radially extending portion of which again comprises an outer flange portion 24 and an inner flange portion 25. The radially extending part of the adjustable flange 23 has generally the same dimensions and shape as the flange 15 and is arranged symmetrically with respect to it. In the sectional view of Figure 3, the angle between the sur faces 21 of the two flange portions 19 and 25 is, therefore, about 10". The flange portion 24 also has, integral with it, a sleeve portion 26, which is coaxial with and at least partly located around the sleeve portion 17 of the flange 15. The sleeve portion 26 is provided on its inner surface with axial splines 27 fitting in axial splines locally provided on the outer surface of the sleeve portion 17 so that the flange 23 is axially slidable along the sleeve portion 17. The axial splines 27 of the sleeve portion 26 are shorter, in an axial direction, than the splines on the outer surface of the sleeve portion 17.

Bolts 28 fasten a cylindrical housing 29 to the adjustable flange 23; this housing 29 is coaxial with the centre line 22 and is displaceable with the disc 23 axially relative to the shaft 13.

Around the outer surface of the sleeve portion 26 projecting in an axial direction out of the disc 23 is arranged a ring 30, which is axially slidable on the sleeve portion 26. For this purpose the inner surface of a cylindrical axially extending part 32 of the ring 30 is provided with axial splines 31 fitting in axial splines on the outer surface of the sleeve portion 26. On the cylindrical part 32 of the ring 30, which part is coaxial with the sleeve portion 26, is provided a radially projecting flange portion 33 which is spaced from the surface of the flange por- tion 24 facing the flange portion 33. Between the cylindrical outer edge of the flange portion 33 and the surrounding inner surface of the housing 29 there is a continuous gap. In the annular space around the cylindrical part 32 inside the housing 29 and between the flange portion 33 and the flange portion 24 are fitted plurality of compression springs 34, the ends of each of which are secured to the flange portion 33 and to the flange portion 24 respectively.

Near the end of the sleeve portion 17 facing away from the flange 15 and near the sleeve portion 26 and the ring 30 an annulus 35 is fitted slidably but not rotatably on the shaft 13 by means of internal axial splines of the annulus 35 which fit in local axial splines on the outer surface of the shaft 13. On the side facing away from the pulley 4, the annulus 35 is supported by a ring 36 on a bearing 37 fitted in the housing 1. The shaft 13 is supported in the housing 1 by the bearing 37.

This end of the shaft 13 is provided with a hydraulic joint 38 for establishing a hydraulic connection between a conduit 39 which in this case projects outside the housing 39 and is stationary with respect to the housing 1 during operation, and an axial bore 40 in the shaft 13, which rotates during operation. The bore 40 extends to the region between the annulus 35 and the adjacent end face of the sleeve portion 17. Between this end face of the sleeve portion 17 and the adjacent end face of the annulus 35 there is an annular gap 41. The bore 40 has radial bores 42 which connect the bore 40 with the gap 41.

Near the outer peripheries of the annulus 35 and of the ring 30 are provided recesses which together form an annular channel 43, into which the gap 41 opens and which is bounded on the outer side by the inner surface of the housing 29. The annulus 35 is hydraulically sealed against the housing 29 on the side of annular channel 43 by a sealing ring 44. The annular channel 43 communicates with the annular recess containing the compression springs 34 through the gap between the flange portion 33 and the housing 29.

The annular channel 43 contains a ring 45 supporting a plurality of radially extending pins 46 on which rollers 47 are mounted for rotation. The rollers 47 are pressure rollers bearing on the one hand on the neighbouring surface of the annulus 35 and on the other hand on the neighbouring surface of the flange portion 33. These two surfaces have arcuate cams 48 which project from the surfaces towards the ring 45 and are shaped so that, when the pressure ring 45 is turned, the ring 30 is entrained by the cams 48 and the rollers 47. The cams 48 are shown in Figure 1.

Between the flange portion 16 and the pressure ring 14 is another ring 45 in an opening of similar shape, this ring also supporting rollers 47 rotatable about radially extending pins, each of the rollers 47 being positioned, in a tangential direction, between cams 48 provided both on the flange portion 16 and on the pressure ring 14.

The flange portions 19 and 25 are made from hardened material.

The pulley 7 and the associated adjusting mechanism 8 is constructed in the same way as the pulley 4 and the adjusting mechanism 5 of Figure 3, the pulley 7 and the adjusting mechanism 8 being, however, arranged in mirror-image fashion with respect to the pulley 4 and the adjusting mechanism 5, as seen in Figure 1. The shaft 10 on which the pulley 7 is mounted, which is analogous to the shaft 13 of Figure 3, constitutes an input shaft for the reversing gear arrangement 9.

Figures 1 and 2 show that this shaft is provided with a pinion 49 in engagement with a pinion 50 on a shaft 51 which is parallel to the shaft 10 supporting the pulley 7.

The shaft 51 has a second pinion 52.

which can be brought into mesh with a pinion 53 fastened to an output shaft 54 extending parallel to the shaft 51. A shaft 55 also extending parallel the shaft 51 is provided with a pinion 56, which is in engagement with the pinion 50. The pinion 53 is slidable along the shaft 54 by means of a fork (not shown) and may be brought at will into engagement with the pinion 56 or 52.

The chain 6 is shown in Figures 4 to 6.

This chain has friction members 57. Each two adjacent friction members 57 are pivotally coupled with one another by means of links 58 and 59. These links are fastened to the friction members 57 so that these members project to either side of the links, whilst, in the region of each friction member s / the links SS and 59 are in direct face-to-face contact with one another. Each friction member 57 comprises two friction elements 60 and 61 intended to transmit by friction the torque to be transferred between the pulleys 4 and 7. The friction element 60 has an outer part 64, having a friction surface 62 which contacts the adjacent flange, and a cylindrical part 63 around which the links 58 and 59 fit closely, the transitional area between the cylindrical part 63 and the outer part 64 forming a shoulder for retaining and supporting the links 58 and 59 on the cylindrical part 63.

The friction element 61 is provided on its side facing the friction element 60 with a cylindrical cavity 65 receiving part of the cylindrical part 63. The surface of the element 61 located around said cavity bears on the links. In the sectional view of Figure 5, the outer surface 62 of the friction element 60 and the outer surface 66 of the friction element 61 are at the same angles as the surfaces 21 of the flanges 15 and 23 so that the sectional view of Figure 5 shows that the friction elements 57 taper.

As viewed radially of the centre line 22 (Figure 6), the outer surfaces 62 and 66 are curved so that the contact surface area between the friction elements 60 and 61 and the adjacent flanges is comparatively small with respect to the whole outer surface 62 or 66 respectively. This contact surface extends radially of the centre line 22 across the whole surface 62 and 66 respectively as shown in Figure 5 and only in the region of the line of intersection of the surface 62, 66 with an axial plane containing the centre line 22 and the centre line of the cylindrical part 63, as shown in Figure 6. The contact with the adjacent flanges is, therefore approximately a linear contact. The friction elements 60 and 61 are interconnected by a connecting member, in this case a pin 67, which extends radially with respect to the centre line 22 and passes through the cylindrical part 63 and the adjacent edges of the friction element 61. In the two holes provided for this purpose in the friction element 61 the pin fits loosely with some radial clearance 68. The friction elements 60 and 61 have aligned bores 69 and 70, which are coaxial with the cylindrical part 63. The bores 69 and 70 go right across the friction members 57 and open out at the surfaces 62 and 66 at the interfaces between the friction members and the adjacent flanges. The bore 70 communicates with bores 71 and 72 opening out at the circumference of the cylindrical part 63 beneath the links. The outer surfaces 62 and 66 are hardened.

As shown in the elevational view of Figure 4 the friction elements 60 and 61 are provided on either end, as viewed lengthwise of the chain 6, with supporting surfaces 73 and 74, which are flat and at a large obtuse angle to one another. The respective surfaces 73 and 74 contact each other when the chain 6 is deflected to the maximum in either direction.

During operation the torque exerted on the input shaft 2 is transferred through the bevel inions 11 and 12 to the shaft 13.

Since the annulus 35 is fastened to the shaft 13 by means of splines, it also rotates. The rollers 47 are engaged by the cams 48 on the annulus 35 and themselves engage cams 48 on the flange portion 33 so that the ring 30 is also rotated. In this way the sleeve portion 26 is rotated by virtue of the splines 31 and hence the whole disc 23 is entrained. By virtue of the splines 27 the sleeve portion 26 rotates the sleeve portion 17 and hence the whole flange 15. The flanges 15 and 23 transmit the rotation through the chain 6 to the pulley 7, which causes the shaft corresponding with the shaft 13 to rotate by way of the mechanisms 8, the output shaft 54 being thus driven in one direction via the pinions 49, 50, 52 and 53 or in the other direction via the pinions 49, 50, 52, 56 and 53 depending upon the position of the slidable pinion 53 which is selected.

The transmission ratio between the pulleys 4 and 6 may be varied by displacing the flanges of each pulley relatively to one another. This displacement is carried out by supplinghydraulic fluid through the conduit 9, the bore 40, the bores 42 and the channel 43 to the annular recess containing the compression springs 34. By increasing the hydraulic pressure the ring 30 and the flange 23 are moved towards the flange 15 so that the chain 6 located between the flanges 15 and 23 is moved radially outwardly of the pulley, the tension of the chain thus increasing. Owing to the comparatively small angle between the flanges 15 and 23 of about 10 , the chain 6 is displaced in a radial direction to a large extent compared with the axial shift of the flange 23.

The compression springs 34 act to clamp the chain 6 between the flanges to take up any clearance, in which case the ring 30 must be movable on the splines 31 along the sleeve portion 26.

Owing to the increase in chain tension the fluid pressure increases in the mechanism 8 in an analogous way to the increase in the mechanism 5. This fluid pressure propagates through a conduit 39A similar to conduit 39 into a control valve (not shown), opens a non-return valve and flows back to the fluid reservoir so that the flanges of the pulley 7 approach one another. In this way a loaddependent pressure force is obtained.

The housing 29 (Figure 3) has an uninterrupted groove 29A receiving a feeler roller of a feedback lever which is coupled with the control lever which controls the admission of fluid through the control slide into the conduit 39. This feedback lever takes up the adjusted position of the flange 23 and moves the control slide back into its initial position, the fluid in the conduits 39 and 39A and in the communicating spaces of the mechanisms 4 and 8 then being locked so that the adjusted position is fixed. Movement of the chain 6 with respect to the pulleys 4 and 7 in the reverse sense is performed in an analogous manner.

As stated above, the friction elements 60 and 61 of each friction member 57 in contact with the flanges 15 and 23 each have two comparatively small contact surfaces with the flanges, these surfaces extending radially of the centre line 22 throughout the radial extent of the friction elements, and having a comparatively small dimension in a tangential direction owing to the curvatures of the outer surfaces 62 and 66. The friction force required for the transmission of the torque is obtained by a comparatively high pressure between the outer surfaces 62, 66 and the adjacent, hardened surfaces 21.

This pressure is propagated through the conduits 39 and 39A respectively. The configuration of the outer surfaces 62, 66 ensure a comparatively high efficiency of the chain pulleys, since the friction losses are comparatively slight compared with what they would be if the outer surfaces 62, 66 were in contact over their whole surface area with the surfaces 21 of the flanges because the overall relative displacements of two contacting points on the contacting surfaces increase with an increase with the contact surface area. Owing to the relative supporting effects in each friction member 57 and to the clearances 68 the friction elements are capable of settling relative to one another in the most advantageous positioned tor reducing unction losses. A portion of the chain 6 may pass through a bath of lubricant, which can thus penetrate between the friction elements and beneath the links through the bores 69 to 72.

The supporting faces 73 and 74 hold each two neighbouring friction members 57 in their relative positions if the straight or curved chain portions are subjected to vibrations which might affect the practical immovability of the contact between the surfaces 62, 66 and 21. Such undesirable chain movements are likely to occur particularly where the chain has its smallest radius but the supporting faces 74 help to limit or even eliminate these movements.

In practice the transmission described is positioned so that the side of the housing 1 where the conduit 39A is located is the top side. When used in, for example, a tractor, the pulleys 4, 7 are, therefore disposed horizontally, the shaft 2 being coupled with the tractor engine and the vertical shaft 54, being perpendicular to the shaft 2, being connected with the driven tractor wheels.

With an input speed of about 2000 rev/min the output speed may be varied between about 260 and 3870 rev/min (i.e. a ratio of torque variation of about 1:15) with a transmissible power of about 200 HP.

WHAT WE CLAIM IS: 1. A chain for a chain transmission, comprising linked friction members each of which has two friction surfaces disposed on opposite sides of the friction member, each friction member comprising two friction elements each having a respective one of the friction surfaces of the friction member, the friction elements being movable relatively to each other to alter the relative positions of the friction surfaces.

2. A chain as claimed in claim 1, in which part of one of the friction elements of each friction member fits around a cylindrical part of the other friction element of that friction member.

3. A chain as claimed in claim 1 or 2, in which the two friction elements of each friction member are intercoupled by a connecting member which loosely engages one of the friction elements with some clearance.

4. A chain as claimed in any one of the preceding claims, in which the two friction elements of each friction member are supported by links interconnecting adjacent ones of the friction members.

5. A chain as claimed in claim 4, in which the friction elements extend at least partly one on each side of the links.

6. A chain as claimed in claim 4 or 5, when appendant to claim 2, in which the links fit around the cylindrical part.

7. A chain as claimed in any one of the preceding claims, in which adjacent friction members are pivotable relative to one another about parallel axes, and in which the friction surfaces are curved. as viewed parallel to the axes.

8. A chain as claimed in any one of the preceding claims, in which the friction surfaces of the friction elements, in a direction perpendicular to the length of the chain, are straight and are inclined to one another.

9. A chain as claimed in claim 8, in which the angle of inclination is about 10 .

10. A chain as claimed in any one of the preceding claims, in which the friction elements have bores for lubricant.

11. A chain as claimed in claim 10, in

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. into a control valve (not shown), opens a non-return valve and flows back to the fluid reservoir so that the flanges of the pulley 7 approach one another. In this way a loaddependent pressure force is obtained. The housing 29 (Figure 3) has an uninterrupted groove 29A receiving a feeler roller of a feedback lever which is coupled with the control lever which controls the admission of fluid through the control slide into the conduit 39. This feedback lever takes up the adjusted position of the flange 23 and moves the control slide back into its initial position, the fluid in the conduits 39 and 39A and in the communicating spaces of the mechanisms 4 and 8 then being locked so that the adjusted position is fixed. Movement of the chain 6 with respect to the pulleys 4 and 7 in the reverse sense is performed in an analogous manner. As stated above, the friction elements 60 and 61 of each friction member 57 in contact with the flanges 15 and 23 each have two comparatively small contact surfaces with the flanges, these surfaces extending radially of the centre line 22 throughout the radial extent of the friction elements, and having a comparatively small dimension in a tangential direction owing to the curvatures of the outer surfaces 62 and 66. The friction force required for the transmission of the torque is obtained by a comparatively high pressure between the outer surfaces 62, 66 and the adjacent, hardened surfaces 21. This pressure is propagated through the conduits 39 and 39A respectively. The configuration of the outer surfaces 62, 66 ensure a comparatively high efficiency of the chain pulleys, since the friction losses are comparatively slight compared with what they would be if the outer surfaces 62, 66 were in contact over their whole surface area with the surfaces 21 of the flanges because the overall relative displacements of two contacting points on the contacting surfaces increase with an increase with the contact surface area. Owing to the relative supporting effects in each friction member 57 and to the clearances 68 the friction elements are capable of settling relative to one another in the most advantageous positioned tor reducing unction losses. A portion of the chain 6 may pass through a bath of lubricant, which can thus penetrate between the friction elements and beneath the links through the bores 69 to 72. The supporting faces 73 and 74 hold each two neighbouring friction members 57 in their relative positions if the straight or curved chain portions are subjected to vibrations which might affect the practical immovability of the contact between the surfaces 62, 66 and 21. Such undesirable chain movements are likely to occur particularly where the chain has its smallest radius but the supporting faces 74 help to limit or even eliminate these movements. In practice the transmission described is positioned so that the side of the housing 1 where the conduit 39A is located is the top side. When used in, for example, a tractor, the pulleys 4, 7 are, therefore disposed horizontally, the shaft 2 being coupled with the tractor engine and the vertical shaft 54, being perpendicular to the shaft 2, being connected with the driven tractor wheels. With an input speed of about 2000 rev/min the output speed may be varied between about 260 and 3870 rev/min (i.e. a ratio of torque variation of about 1:15) with a transmissible power of about 200 HP. WHAT WE CLAIM IS:

1. A chain for a chain transmission, comprising linked friction members each of which has two friction surfaces disposed on opposite sides of the friction member, each friction member comprising two friction elements each having a respective one of the friction surfaces of the friction member, the friction elements being movable relatively to each other to alter the relative positions of the friction surfaces.

11. A chain as claimed in claim 10, in

which the bores provided in the two friction elements of each friction member communicate with one another.

12. A chain as claimed in claim 10 or 11, in which the bores open at the friction surfaces.

13. A chain as claimed in any one of the preceding claims, in which the friction elements have supporting surfaces, the supporting surfaces of neighbouring friction members being positioned for engagement with one another.

14. A chain as claimed in claim 13, in which each friction element has two supporting surfaces which are inclined to one another and which face the respective adjacent friction members.

15. A chain for a chain transmission substantially as described herein with reference to and as illustrated in the accompanying drawings.

16. A chain transmission including a chain in accordance with any one of the preceding claims.