GB2186945A

GB2186945A - Chain for continuously variable cone-pulley belt-drive transmissions

Info

Publication number: GB2186945A
Application number: GB08703500A
Authority: GB
Inventors: Ernest Kolh
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1986-02-19
Filing date: 1987-02-16
Publication date: 1987-08-26
Also published as: FR2594513A2; GB2186945B; FR2594513B2; GB8703500D0

Abstract

A chain for continuously variable cone-pulley belt-drive transmissions, comprises a plurality of trapezoidal plates (1, 1') arranged in close succession and which are held together by means of tie elements (2, 3) so as to form an endless driving strand. Each plate (1, 1') is formed with four holes lying on a line parallel to and substantially mid-way between the parallel sides of the trapezium, the two inner holes receiving two respective links pins (2) which connect the plate to one of the two adjacent plates of the chain and the two outer holes receiving two further respective link pins (3) connecting the plate to the other of the two adjacent plates of the chain. In the present invention, the plates (1, 1') are held in tension against one another and their mating surfaces (20, 21) are configured to permit adjacent plates to roll about one another. <IMAGE>

Description

SPECIFICATION Chain for Continuously Variable Cone-pulley Beltdrive Transmissions The invention relates to a chain for continuously variable cone-pulley belt-drive transmissions, comprising a plurality of trapezoidal plates arranged in close succession and which are held together by means of tie elements so as to form an endless driving strand, wherein each plate is formed with four holes lying on a line parallel to and substantially mid-way between the parallel sides of the trapezium, the two inner holes receiving two respective links pins which connect the plate to one of the two adjacent plates of the chain and the two outer holes receiving two further respective link pins connecting the plate to the other of the two adjacent plates of the chain.Such a chain is the subject of British Patent Appin. No. 8609560 of which the present invention is an improvement.

Open-link chains for continuously variable cone pulley belt-drive transmissions are known from German Patent No. 24 41 569 and European Patent 0 014 492, comprising a plurality of trapezoidal plates following in close succession and which are flattened in the region of their shorter trapezium base and are held together touching one another by way of tie elements to form an endless driving strand.

In this case steel belts disposed laterally in slots in the trapezoidal plates or in central recesses in the trapezoidal plates are provided as tie elements.

These known chains have the disadvantage that they can be designed only as thrust belts requiring higher pressure forces between the cone pulleys and the link chain. The endless steel belts are also difficult to control, in particular in their multipielayer arrangement. Furthermore, the irregular frictional contact between the trapezoid plates and the endless steel belts embracing them soon results in wear and failure of the entire chain.

The invention in Patent Application No. 8609560 mitigates the foregoing problems encountered in the prior art and the present invention seeks to improve the smooth running of the chain of the latter Application.

According to the present invention, there is provided a chain for continuously variable conepulley belt-drive transmissions, comprising a plurality of trapezoidal plates arranged in close succession and which are held together by means of tie elements so as to form an endless driving strand, wherein each plate is formed with four holes lying on a line parallel to and substantially mid-way between the parallel sides of the trapezium, the two inner holes receiving two respective links pins which connect the plate to one of the two adjacent plates of the chain and the two outer holes receiving two further respective link pins connecting the plate to the other of the two adjacent plates of the chain, characterised in that the plates are held in tension against one another and their mating surfaces are configured to permit adjacent plates to roll about one another.

In Patent Application No. 8609560 embodiments having trapezoidal plates arranged a slight distance apart are described and illustrated. By contrast, in the present invention, the plates are held in tension against one another and their mating surfaces are configured to permit adjacent plates to roll about one another.

Because the pairs of link pins joining adjacent plates members are mounted with slight pretensioning and the adjacent plate members bear against with one another over a convex curved surface, a particular smooth running of the chain is achieved while avoiding troublesome power peaks and noise during fluctuations in the traction force.

The invention enables smoothness comparable with that of so-called thrust belts to be achieved even though the chain of the invention acts as a traction belt.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a view of a trapezoidal plate of an openlink chain according to the invention, the plate being split along a centre line, Fig. 2 is a partial side view shown partly in section, of an open-link chain, Fig. 3 is a partial plan view shown partly in section of the chain in Fig. 2, Fig. 4 is a partial side view, drawn to a greatly enlarged scale, of two adjacent plates when the chain is extended, and members with the open-link chain extended, and Fig. 5 is a similar view to Fig. 4 when the chain is bent.

As shown in Figs. 1 to 3, an open-link chain comprises a plurality of trapezoidal plates 1 and 1' which follow one another in succession and bear against one another. The plates 1,1' are flattened in known manner on their shorter trapezium base to permit bending of the chain and are connected to one another by way of pairs of link pins 2 and 3.

Each plate is connected to one adjacent plate by the inner pins 2 and to the other by the outer link pins 3.

As shown in Fig. 4, in particular, the trapezoidal plates 1 and 1' have bores 4 and 5 both disposed halfway up the trapezium which are arranged symmetrically and of which the inner pair in each case is provided with ball cup surfaces 6 and 7 facing one side and the outer pair in each case is provided with ball cup surfaces 8 and 9 facing the other side.

The link pins 2 and 3 comprise a head i 1, a shaft 12 and afoot 13. The faces of the head 11 and the foot 13 nearerthe shaft 12 are provided with universal-ball-joint faces which cooperate in an articulated manner with the corresponding ball cup surfaces in the trapezoidal plates 1 and 1'.

The plates 1 and 1' are provided with an oblique flattening 24 starting from the centre line towards their shorter trapezium base. The faces 20 and 21 on the plates 1 and 1', are shaped in such a manner that as the belt is bent, the individual plates roll over one another with the distance between associated universal-ball-joint surfaces remaining constant and equal to the distance between the bolt heads. This prevents the plates from lifting off one another and from being deformed.

As explained in particular by reference to Fig. 5, the contact surface 21 must perform a specific function, as the contact surface 20 is essentially a flat surface.

In Figs. 4 and 5, the centres of curvature of the spherical surfaces of a link pin 2 are designated M1 and M2. The angle oftilt between the plates 1 and 1' is designated (p. The distance between the points M1 and M2 is designated t. For all values of the angle cp, the distance t is given by the equation t=S1 +S2/cos ((p/2) where S1 is the distance of the point of contact from the centre of curvature M1, and S2 is the perpendicular distance from the point M2 to the flat surface 20, this being the distance between the point M2 and the tangent to the surface 21 at the point of contact.

Therefore, if the contact surface 21 satisfies the equation S1=t-S2/cos ((p/2) then the distance between the points M1 and M2 will not vary and no tension occurs in the link as the plates tilt.

Claims

1. A chain for continuously variable cone-pulley belt-drive transmissions, comprising a plurality of trapezoidal plates arranged in close succession and which are held together by means of tie elements so as to form an endless driving strand, wherein each plate is formed with four holes lying on a line parallel to and substantially mid-way between the parallel sides of the trapezium, the two inner holes receiving two respective links pins which connect the plate to one of the two adjacent plates of the chain and the two outer holes receiving two further respective link pins connecting the plate to the other of the two adjacent plates of the chain, characterised in that the plates are held in tension against one another and their mating surfaces are configured to permit adjacent plates to roll about one another.

2. A chain according to Claim 1, wherein one link has a flat surface and the other a curved surface which satisfies the equation S1=t-S2/cos ((p/2) where t is the distance between the centres of curvature M1 and M2 of spherical surfaces of the link pin joining the adjacent plates, is the tilting angle between the two adjacent plates, and S1 is the distance of any point on the curved surface from the centre of curvature M1.

3. A chain constructed, arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.