DRIVE BELT WITH A CARRIER RING AND TRANSVERSE SEGMENTS

Abstract

The disclosure relates to a transverse segment (33) for a drive belt with a carrier ring and with a plurality of these transverse segments (33) that are placed slideably on the carrier ring, which transverse segments (33) are provided with main body surfaces (38, 41), where between the transverse segment (33) extends in thickness direction, one main body surface (38) being provided with a rocking edge (42) that defines a transition between an upper side and a tapered lower side of the transverse segment (33) with a lowermost edge (34). The lower side of the transverse segment (33) includes at least one opening (44) and at least an upper, radially outward limiting boundary surface (46) of the opening (44) is provided with an undulating shape, i.e. is provided with multiple protrusions (47) that protrude generally towards the lower, radially inward limiting boundary surface (46) of the opening (44).

Claims

1. A transverse segment (33) for a drive belt (3) with a carrier ring (31) and with a number of such transverse segments (33) that are slideably mounted on the carrier ring (31), which transverse segment (33) is provided with two friction surfaces (43), between which friction surfaces (43) the transverse segment extends in width direction, and with two main body surfaces (38, 41), between which main body surfaces (38, 41) the transverse segment (33) extends in thickness direction, whereof at least one main body surface (38) is provided with a transition surface (42) that extend in width direction and that forms a transition between an outermost part of the transverse segment (33) with a predominantly constant thickness and an innermost part of the transverse segment (33) whereof the thickness reduces in height direction away from the transition surface (42), which transverse segment (33) is further provided with at least one opening (44) that is located in the said innermost part and that cuts in thickness direction through the transverse segment (33), characterized in that at least one of an upper boundary surface (46) of the opening (44) located on the top side thereof and a lower boundary surface (45) thereof located on the bottom side thereof is provided with protrusions (47), i.e. is undulating.

2. The transverse segment according to claim 1, characterized in that either only the upper boundary surface (46) or only the lower boundary surface (45) of the opening (44) is provided with the said protrusions (47) and in that the respective other boundary surface (46; 45) of the opening (44) is an essentially flat surface.

3. The transverse segment according to claim 1, characterized in that only the upper boundary surface (46) of the opening (44) is provided with the said protrusions (47) and in that the lower boundary surface (45) is an essentially flat surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above technical principles underlying the present disclosure, as well as detailed embodiments of the transverse segment realised thereby are elucidated further by way of example on the basis of the description below with reference to the drawing, in which:

[0011] FIG. 1 provides a schematically representation of the known continuously variable transmission with two pulleys and a drive belt;

[0012] FIG. 2 illustrates a transverse segment of the drive belt according to FIG. 1, both in a front and in a side elevation thereof;

[0013] FIG. 3 provides a first novel embodiment of the transverse segment in a schematic front elevation thereof; and

[0014] FIG. 4 provides a second novel embodiment of the transverse segment in a schematic front elevation thereof.

DETAILED DESCRIPTION OF THE INVENTION

[0015] In the figures, identical reference numbers relate to identical or at least comparable technical features.

[0016] FIG. 1 shows the central parts of a known continuous variable transmission, as is commonly applied in the drive line of personal vehicles between the engine and the drive wheels thereof. The transmission comprises two pulleys 1, 2, each provided with two pulley sheaves 4, 5, and a drive belt 3 that is wrapped around the said pulleys 1, 2, located clamped between the respective pulley sheaves 4, 5 thereof. The pulley sheaves 4, 5 are shaped generally conical and at least one pulley sheave 4 is incorporated in the transmission axially moveable along a respective pulley shaft 6, 7 over which it is placed. The transmission also comprises activation means that impose on the said at least one sheave 4 an axially oriented force Fax directed towards the respective other pulley sheave 5, such that the belt 3 is clamped there between and a rotational movement and accompanying torque can be transmitted between the pulleys at a variable transmission ratio. During operation of the transmission, lubrication oil is circulated to reduce friction and to cool the moving parts thereof, such as the drive belt 3.

[0017] The drive belt 3 comprises at least one endless or ring-shaped carrier 31 and a number of transverse segments 33, with the carrier ring 31 extending through a recess 37 provided in the transverse segments 33, such that these are moveable along the circumferential direction of the carrier ring 31.

[0018] As is shown in more detail on the left-hand side of FIG. 2 in a cross-section of the drive belt 3, the carrier ring 31 consists of two parts 31, each such part being composed of a number of individual bands 32 that are narrowly fitted around one another. The transverse segments 33 are basically metal plates that are facing in the circumferential direction of the carrier ring 31. The transverse segments 33 comprises three basic portions, namely an essentially trapezoidal base portion 34, a head portion 36 and a web portion 35 provided in-between and connecting the base portion 34 and the head portion 36. A width dimension of the web portion 35 is less than a corresponding width of the base portion 34 and the head portion 36, whereby the said recess 37, where through the carrier ring 31 extends in the drive belt 3, is defined between the said base portion 34 and head portions 36 thereof. In the drive belt 3, adjacent transverse segments 33 abut one another through their respective front and rear main body surfaces 38, 41 as is shown for a pair of adjacent transverse segments 33 on the right-hand side of FIG. 2.

[0019] On either side of the base portion 34 thereof, the known transverse segment 33 is provided with a friction surface 43, which friction surfaces 43 are mutually oriented at an angle that is narrowly controlled in manufacture and which friction surfaces 43 serve to frictionally engage the pulley sheaves 4, 5 of the transmission pulleys 1, 2, at least during operation. Further, the known transverse segment 33 include a stud 39 projecting from the front main body surface 38 and a recess 40 provided in the back main body surface 41. In the drive belt 3, the stud 39 of a first transverse segment 33 of a pair of adjacent transverse segments 33 is at least partly inserted in the recess 40 of a second transverse segment 33 of such pair, whereby these transverse segments 33 mutually align each other perpendicular to the said circumferential direction.

[0020] To allow the drive belt 3 to bend, i.e. to follow a curved trajectory around the pulleys 1, 2, a radially innermost part of the transverse segments 33 tapers in radially inward direction, either gradually (such as illustrated on the right-hand side of FIG. 2), stepwise or a combination thereof. A transition surface 42 between such, at least effectively tapered, radially innermost part and another part of each respective transverse segments 33, located radially outward thereof and having a largely constant thickness, extends in the axial direction on the front main body surface 38 from one axial side of the base portion 34 to the other axial side, i.e. in-between the said friction surfaces thereof 43. This transition surface 42 is typically convexly curved and defines an axis of rotation between each pair of adjacent transverse segments 33. Such transition surface 42 is commonly referred to in the art as the rocking edge 42 of the transverse segment 33.

[0021] In the base portion 34 of the transverse segment 33 two cut-throughs, i.e. holes 44 are provided below, i.e. radially inward of the rocking edge 42. By the number and size of these holes 44 the weight of the transverse segment 33 (and thus also of the drive belt 3 as a whole) can be adjusted and/or a heat transfer away from the friction surfaces 43 to the lubrication oil can be influenced.

[0022] In a first novel embodiment of the transverse segment 33 that is illustrated in FIG. 3 in a schematic front elevation thereof the surfaces 45, 46 of the transverse segment 33 defining the holes 44 are provided with an undulating shape. Hereby the area of the external surface of the transverse segment 33, available for heat transfer away from the transverse segment 33 during operation, is increased, favourably without increasing the number or size of the holes 43 that would reduce the strength and/or stiffness of, in particular, the base portion 34 of the transverse segment 33.

[0023] In a second novel embodiment of the transverse segment 33, that is illustrated in FIG. 4 in a schematic front elevation thereof, only an upper, radially outward limiting or boundary surface 46 of the holes 44 is undulated, i.e. is provided with multiple protrusions 47 extending in radially inward direction. A lower radially outward limiting or boundary surface 45 of the holes 44 is an essentially flat surface. In this second embodiment, parts of the base portion 34 of the transverse segment 33 located above, i.e. radially outwards of the holes 44 will be cooled more effectively that parts thereof located below the holes 34. Hereby, the tapered shape of the base portion 34 with more material above the holes 44 than below these holes 44 is taken into account and the cooling rate of those respective parts will be favourably more equal.

[0024] The present disclosure, in addition to the entirety of the preceding description and all details of the accompanying figures, also concerns and includes all the features of the appended set of claims. Bracketed references in the claims do not limit the scope thereof, but are merely provided as non-binding examples of the respective features. The claimed features can be applied separately in a given product or a given process, as the case may be, but it is also possible to apply any combination of two or more of such features therein.

[0025] The invention(s) represented by the present disclosure is (are) not limited to the embodiments and/or the examples that are explicitly mentioned herein, but also encompasses amendments, modifications and practical applications thereof, in particular those that lie within reach of the person skilled in the relevant art.