CN113090724A

CN113090724A - Transverse segment for a drive belt, drive belt comprising a transverse segment and continuously variable transmission having a drive belt comprising a transverse segment

Info

Publication number: CN113090724A
Application number: CN202011527286.0A
Authority: CN
Inventors: P·里贝斯
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-12-23
Filing date: 2020-12-22
Publication date: 2021-07-09
Also published as: NL1043519B1

Abstract

The invention relates to a transverse segment (1) for a drive belt (50), said drive belt (50) comprising a row of such transverse segments (10) mounted on a ring stack (8). The transverse section (10) defines a central opening (5) between a base (10) of the transverse section (10) and two pillar portions (11) thereof extending from respective sides of the base (10) for accommodating the stack of rings (8). Each post (11) is provided with a conical projection (6) protruding from the front surface (2) of the transverse section (1) and has a corresponding conical cavity (7) provided in the rear surface (3) of the transverse section (1). According to the invention, the value of the cone half-angle of the protuberance (6) and the cavity (41) is in the range of 3.5 to 6.5 degrees, with 5 degrees being the optimum value.

Description

Transverse segment for a drive belt, drive belt comprising a transverse segment and continuously variable transmission having a drive belt comprising a transverse segment

Technical Field

The invention relates to a transverse segment and a drive belt, which transverse segment is intended to be part of a drive belt for a continuously variable transmission having two pulleys. Such transmissions are well known and are used, for example, in the drive trains of passenger cars and other motor vehicles. In the transmission, the drive belt runs around and between pulleys, which are each provided with two conical sheaves, which define a V-groove in which a respective circumferential portion of the drive belt is held. By moving the pulley sheaves towards or away from each other, respectively, the width of the V-grooves of the pulleys can be varied in opposite directions to control the radius of (effective) frictional contact of the drive belt with the respective pulleys, i.e. to control the speed ratio provided by the transmission over a continuous range between a minimum and a maximum speed ratio.

Background

The known type of drive belt comprises a row of substantially continuous transverse segments made of steel mounted thereon around the circumference of a ring stack consisting of a plurality of flexible annular bands or rings, also made of steel, stacked one on top of the other.

In the above and the following description, the axial, radial and circumferential directions are defined with respect to the drive belt when placed in a circular posture. The thickness direction and the thickness dimension of the transverse segment are defined in the circumferential direction, the height direction and the height dimension of the transverse segment are defined in the radial direction, and the width direction and the width dimension of the transverse segment are defined in the axial direction. A thickness direction and a thickness dimension of the ring and the ring stack are defined in the radial direction, a width direction and a width dimension of the ring and the ring stack are defined in the axial direction, and a length direction and a length dimension of the ring stack are defined in the circumferential direction. An up-down direction and an up-down position are defined in the radially outward and radially inward directions, respectively.

Known flexible rings are provided with a substantially rectangular cross-section such that they have a radial dimension or thickness that is much smaller than their axial dimension or width, typically at least one-fourths to one-hundredth or less. Also in absolute terms, the thickness of the ring is small and typically has a value of 185 to 200 microns, so that it can be bent relatively easily in its circumferential direction. In a ring stack, a plurality of such rings are arranged concentrically with respect to each other, i.e. nested with narrow tolerances, so that when the drive belt is running in a transmission, the rings share the load.

The known transverse segments each define a central opening which is open towards the radially outer side of the drive belt, said central opening accommodating and confining a respective circumferential section of such a ring stack, while allowing the transverse segments to move in their circumferential direction. The central opening is defined between a transverse segment base located radially inward of the stack of rings and two pillar portions extending from respective sides of the base in a radially outward direction. Thus, the two pillar portions define respective axial boundaries of the central opening, while in a radially inward direction the central opening is bounded by the base portion. In the radially outward direction, the central opening is at least partially blocked in a manner so as to confine the ring stack in the central opening. Drive belts of this type are known, for example, from British patent GB1286777-A and more recently from International patent publication WO 2018/210456-A1. It is noted that according to these documents, the means for limiting the ring stack in the radially outward direction are realized by respective hook portions of the post portions, which hook portions of each post portion axially extend at a distance from the base portion towards the respective other, i.e. axially opposite post portion. The hooks of the transverse segments may have equal axial extension or the axial extension between two hooks may be different, in which case for successive transverse segments in the drive belt the respective hooks are preferably arranged on opposite sides of the transverse segment, in particular as taught by WO2018/210456a 1.

It is known that the outer portion of the transverse segment is provided with a substantially constant thickness, seen in the radial direction, while the thickness of the inner portion thereof decreases in the radially inward direction. Between said inner and outer parts, the front surface of the transverse segment facing in the circumferential direction of the drive belt comprises a radially curved surface portion extending in the width direction, which is often referred to in the art as a rocking edge or tilting zone. The rocking edge allows successive transverse segments in the drive belt to rotate relative to each other about the axial direction while these transverse segments remain in contact at the rocking edge, whereby the drive belt as a whole follows a curved trajectory. Although the rocking edge may be located in the base of the transverse section, it is preferably located at least partially in the post of the transverse section.

During operation of the transmission, the ring stack is tensioned by clamping the transverse segments between the conical discs of the two pulleys, by pushing the transverse segments in a radially outward direction at the two pulleys. At these pulleys, the drive belt therefore follows a curved trajectory, wherein the curved trajectory part of the transverse section abuts against the radially inner side of the ring stack at least by a part of the surface of its base part between the pillar parts, which surface part will be denoted as bearing surface in the following. Due to its said tension on the pulleys, the stack of rings extends substantially straight between the two pulleys, while guiding the transverse segments as they travel from one pulley to the other with such a straight trajectory part.

It is common practice in the art to provide the transverse segments with protrusions projecting from said front surface or from an oppositely facing rear surface thereof, and to provide corresponding but slightly larger cavities in their respective opposite main surfaces. In a row of transverse segments in the drive belt, the projections of a first transverse segment are at least partially received in the cavities of a second, i.e. adjacent, transverse segment. The mutual displacement of successive transverse segments perpendicular to the circumferential direction of the drive belt is therefore limited to the play of the protrusions in the cavities. The projections and cavities thus serve to align the transverse segments in rows with one another in a straight portion of the trajectory of the drive belt and to limit their rotation in said curved trajectory portion. In particular, at least the pitch (i.e. rotation around the axial direction) and yaw (i.e. rotation around the radial direction) of the transverse segments, and preferably also the roll (i.e. rotation around the tangential direction) of the transverse segments relative to the ring stack, are limited. The known transverse segments each comprise a single protrusion (and corresponding cavity) arranged centrally in their base and/or two protrusions (and corresponding cavities) arranged one in each of their columns. Generally, in the art, a play of between 0.015mm and 0.05mm, preferably of about 0.025mm, is applied in any direction perpendicular to the circumferential direction of the protrusion, i.e. between the inner circumference of the cavity and the outer circumference of the protrusion centrally located in the cavity.

It should be noted that conventionally, the protrusions and cavities have a frustoconical shape, i.e., are formed as a frustoconical shape, as required by its preferred molding process. Indeed, the protuberances and cavities have a conical half-angle (i.e. half the apex angle of the truncated cone) of at least 7 to 8 degrees, theoretically tending to the larger values represented by EP1662174a1 and WO2012/091546a 1.

Disclosure of Invention

It is a basic object of the present invention to improve existing drive belt designs and existing design considerations with respect to wear resistance and/or fatigue strength of known drive belts. The improvement observed in this respect, when the conicity of the projections and cavities of the transverse segments of the drive belt is reduced with respect to said prior art design, while maintaining a known, i.e. conventional, range of play between the two, is surprising, i.e. surprising in comparison with the prior art knowledge.

In the design of the drive belt under consideration at present, the ring stack is confined in the central opening of the transverse section in the opposite axial direction, i.e. in the width direction, by and between the column parts thereof. The width of the ring stack is slightly smaller than the width of the central opening of the transverse segments to accommodate mutual misalignment, i.e. axial offset between the pulley V-grooves during operation of the transmission, depending on the speed ratio, as taught in particular by US 4820242. However, such an axial clearance of the ring stack relative to the transverse segments cannot prevent a common contact between the ring stack and the stud portion during operation of the drive belt, by which the ring stack is worn. Thus, reducing the severity of such contact, for example in terms of incidence and/or strength thereof, is beneficial to the overall performance of the belt. By applying the conical half-angle according to the invention, it can be appreciated that the relative movement between successive transverse segments in the axial direction is also minimal when the projections of the successive transverse segments are not fully inserted into the respective cavities, thereby promoting a preferred alignment of the transverse segments with respect to the ring stack and advantageously reducing the severity of said contact. After all, by minimizing this axial play between the protrusion and the cavity, the axial clearance between the transverse section and the ring stack is maximized.

In particular, according to the invention, the value of the cone half-angle is in the range of 3.5 degrees to 6.5 degrees, with 5 degrees being the optimum value. In relation to the lower boundary of this range, it is noted that not only does unwanted side effects start to catch up in the wind, but also after pressing into shape in such a mould, it becomes increasingly difficult to release the protrusion from the mould. Further according to the invention, in this case said axial clearance of the ring stack relative to the transverse section may advantageously be set small, in particular relatively 6% or less of the width of the ring stack, or, absolutely, only 1.5 to 2 times the maximum axial offset of the pulley V-grooves in the transmission, typically 0.4 to 0.5 mm.

Drawings

The above-described invention and the technical working principle underlying the invention will now be further explained with reference to the accompanying drawings, in which:

FIG. 1 is a simplified schematic side view of a known transmission having two pulleys and a drive belt including a ring stack and a row of transverse segments mounted on the ring stack circumferentially thereof;

figure 2 schematically shows a cross section of the known drive belt in its circumferential direction and also comprises a separate cross section of only its transverse segments;

fig. 3 schematically shows a cross section of a known transverse segment in an enlarged view;

figures 4A and 4B schematically illustrate aspects of the operation of a known drive belt; and

fig. 5 is a diagram showing a technical consideration underlying the present invention.

Detailed Description

Fig. 1 schematically shows in cross section a central part of a continuously variable transmission 51 for a drive train of, for example, a passenger car. The transmission 51 is well known and includes at least a first variable pulley 52, a second variable pulley 53, and a transmission belt 50 mounted around these

pulleys

52, 53. In the drive train, a first pulley 52 is coupled to and driven by a prime mover (e.g., an electric motor or an internal combustion engine) of the vehicle, and a second pulley 53 is coupled to and drives driven wheels of the vehicle, typically via a plurality of gears. The

pulleys

52, 53 each typically comprise a first conical sheave fixed to the

respective pulley shaft

54, 55 and a second conical sheave axially movable relative to the

respective pulley shaft

54, 55 and fixed in the direction of rotation. As shown in fig. 1, the trajectory of the drive belt 50 in the transmission 50 includes two straight portions ST, across which the drive belt 50 spans between the

pulleys

52, 53, and two curved portions CT, around which the drive belt 50 wraps around the two

pulleys

52, 53 while being accommodated between the tapered sheaves thereof.

The drive belt 50 consists of a ring stack 8 and a plurality of transverse segments 1, which transverse segments 1 are mounted on the ring stack 8 in at least substantially continuous rows along the circumference of the ring stack 8. For the sake of simplicity, only a few transverse segments 1 of the drive belt 50 are shown in fig. 1, which transverse segments 1 are furthermore not drawn to scale with respect to the diameter of the

pulleys

52, 53, for example. In the drive belt 50, the transverse segments 1 are movable in the circumferential direction of a ring stack 8, which ring stack 8 consists of a number of relatively thin and flexible annular steel bands or rings nested inside one another, as can be seen more clearly in fig. 2, which shows a ring stack 8 with eight individual rings.

During operation of the transmission 51, the transverse section 1 of the drive belt 50 can be driven by the first pulley 52 in its rotational direction by friction. These driven transverse segments 1 push the preceding transverse segment 1 in the circumferential direction of the ring stack 8 and finally rotationally drive the second pulley 53 again by friction. In order to generate such friction (force) between the transverse segment 1 and the

pulleys

52, 53, the pulley sheaves of each

pulley

52, 53 are urged towards each other, whereby these pulley sheaves clamp the transverse segment 1 between them in the respective curved track portion CT of the drive belt 50. For this purpose, an electronically controllable and hydraulically acting movement device (not shown) is provided in the transmission 51, which acts on the movable pulley sheaves of each

pulley

52, 53. These kinematic means also control the respective radial positions R1 and R2 of the drive belt 50 at the

pulleys

52, 53 and thus the speed ratio provided by the variator 51 in the drive train between its

pulley axles

54, 55.

Also during operation of the transmission 51 drive belt 50, the cross members are urged radially outwards by being clamped between the conical pulley sheaves and are forced into contact with the radially inner side of the ring stack 8 tensioned thereby. Since, as mentioned above, in the drive belt 50 the transverse segments 1 are movable in their circumferential direction relative to the ring stack 8, the ring stack 8 is tensioned to a relatively low level relative to the torque transmitted by the drive belt 50 between the

pulleys

52, 53, at least in comparison with other types of drive belts.

In fig. 2, a known drive belt 50 is schematically shown in more detail. On the left side of fig. 2, the drive belt 50 is shown in a cross section in the circumferential direction, on the right side of fig. 2, comprising only the cross section a-a of the transverse section 1. As can be seen from fig. 2, the transverse section 1 of the drive belt 50 is shaped substantially like the letter "V", i.e. substantially V-shaped. In other words, the flanks 12 of the transverse segment 1 expand in the radially outward direction by being oriented at an angle by which the transverse segment 1 comes into (frictional) contact with the

pulleys

52, 53, which angle closely matches the angle existing between the conical sheaves of these

pulleys

52, 53. The pulley contact surfaces 12 of the transverse segments 1 are usually corrugated from a macroscopic contour or provided with a rough surface structure, so that only the higher peaks of the corrugations or of the surface roughness come into contact with the

pulleys

52, 53. This particular feature of the transverse segment design enables the friction between the drive belt 50 and the

pulleys

52, 53 to be optimized by allowing the cooling oil applied in the known transmission 51 to be contained in the lower part of the corrugations or surface roughness.

Each transverse segment 1 comprises a base part 10 and two pillar parts 11, wherein the base part 10 extends mainly in the axial direction of the drive belt 50 and the pillar parts 11 each extend from a respective axial side of the base part 10 mainly in the radial direction of the drive belt 50. In its thickness direction, the transverse segment 1 extends between its front body surface, i.e. the front surface 2, and a rear body surface, i.e. the rear surface 3, which are both oriented at least substantially in the circumferential direction of the drive belt 50. An opening 5 is defined centrally between the pillar portion 11 and the base portion 10 of each transverse segment 1, a circumferential section of the ring stack 8 being received in the opening 5. The central opening 5 is partially blocked in the radially outward direction by the corresponding hook portion 9 of the post portion 11. Each such hook portion 9 extends generally from a respective post portion 11 in the direction of a respective opposing post portion 11. Thus, the hooks 9 confine the ring stack 8 in a radially outward direction to the central opening 5 of the transverse segment 1. Between the column parts 11, the base part 10 defines a support surface 13 for restraining and supporting the ring stack 8 in a radially inward direction.

As shown in fig. 2, the bearing surface 13 is a central part of the boundary surface of the central opening 5, which is defined by the base part 10 in a radially inward direction and thus extends mainly in the axial and circumferential direction of the drive belt 50. The bearing surfaces are convexly curved at least in the axial direction in a well-known manner to achieve or at least promote the desired contact and interaction between the transverse segment 1 and the ring stack 8. On either side of the support surface 13, said boundary surface of the base part 10 also comprises a transition surface 15, said transition surface 15 forming a transition between the support surface 13 and the side surface of the respective pillar part 11 facing the central opening 5. Typically, such transition surfaces 15 include a convex curvature adjacent the bearing surface 13 and a concave curvature adjacent the side surface of the respective post 11. Note that the convex curved portion of the transition surface 15 is curved according to a radius of curvature that is much smaller (e.g., 0.1 times or less) than the radius of curvature at which the support surface 13 is curved.

Both pillar portions 11 of the transverse segment 1 are provided with a projection 6 protruding in the thickness direction from the front surface 2 of the transverse segment 1 and have a corresponding but slightly larger cavity 7 in the opposite side of the respective pillar portion 11, i.e. in the rear surface 3 of the transverse segment. In the row of transverse segments 1 in the drive belt 50, the projection 6 of a first transverse segment 1 is received in the cavity 7 of a second, i.e. adjacent, transverse segment 1. By this engagement of the projections 6 and the cavities 7 of successive transverse segments 1, the transverse segments 1 are interlinked and aligned with each other in the radial direction and in the axial direction in said row in the drive belt 50. In fig. 2, the diameter of the cavity 7 is enlarged relative to the diameter of the protrusion 6 to show the play that exists between them.

Also in said row of transverse segments 1 in the drive belt 50, at least a part of the front surface 2 of a first transverse segment 1 abuts at least a part of the rear surface 3 of a second, i.e. adjacent, transverse segment 1. The adjoining transverse segments 1 can be inclined relative to one another while being held in mutual contact at the axially extending, convexly curved surface portions 4 of their front surface 2 and by the surface portions 4, the surface portions 4 being referred to hereinafter as rocking edges 4. Above such a rocking edge 4, i.e. radially outwards, the transverse segment 1 has a substantially constant thickness, whereas below such a rocking edge 4, i.e. radially inwards, the transverse segment 1 is tapered, i.e. its thickness decreases in a radially inwards direction (gradually, stepwise or by a combination thereof), to allow the aforementioned relative tilting without interference between the respective bases 10 of adjacent transverse segments 1.

It is to be noted that although in fig. 2 the rocking edge 4 is located partly in the pillar portion 11 of the transverse segment 1 and partly in the base portion 10 of the transverse segment 1, so that it overlaps the support surface 13 in the radial direction, it is also known to locate the rocking edge 4 completely in the base portion 10, i.e. radially inside the support surface 13. In both cases, the rocking edge 4 is preferably provided in two portions 4a, 4b, the two portions 4a, 4b being separated by a central opening 5 and/or by a recessed area 14 in the front surface 2 of the transverse segment 1 which is recessed in the thickness direction with respect to the rocking edge 4. The recessed areas 14 provide channels between adjacent transverse segments 1, allowing lubricant to flow from the radially inner side of the drive belt 50 to the radially inner side of the ring stack 8. This lubricant is supplied to the transmission during operation, not only for cooling the transmission, but also for lubricating the dynamic contact between the transverse section 1 and the ring stack 8 and between the individual rings of the ring stack 8. It should also be noted that in the embodiment of the transverse segment 1 shown in fig. 2, in which the rocking edge 4 is located partly in the pillar portion 11 and the base portion 10 of the transverse segment 1, the recessed area 14 is formed partly as a curved transition surface between the front surface 2 and the bearing surface 13 of the transverse segment 1, which is an unavoidable side effect of the preferred manufacturing method of fine blanking the transverse segment. In fine blanking, the transverse segment 1 is cut from the base material by pressing a punch having a profile corresponding to the profile of the transverse segment 1 through the base material into a transverse segment bore of the die plate while being supported by counter-punches on opposite sides thereof. The end face of the counter-punch in contact with the base material is shaped to form the rocking edge 4 and is provided with a recess which serves as a die for forming the protrusion 6, while the end face of the punch in contact with the base material is the protruding part to form the cavity 7.

As further shown in fig. 2, the pulley contact surface 12 of the transverse segment 1 extends in the radial direction from the bottom side of the base part 10 to slightly above the rocking edge 4, i.e. partly in the column part 11. However, this radial extension may also be less, for example the pulley contact surface 12 may be limited to the base portion 10, or more, for example the pulley contact surface 12 may extend radially outside the ring stack 8 in the column portion 11.

FIG. 3 shows the projection of one of the column parts 11 in more detail for two successive transverse sections 1a, 1B according to the cross section B-B in FIG. 26 and a cavity 7. In fig. 3 it can be seen that the protrusion 6 and the cavity 7 have a (frusto) conical shape with the same conical half-angle

Fig. 3 also shows that a play is provided between the outer periphery of the protrusion 6 and the inner periphery of the cavity 7. The play between the protrusions 6 in the cavity 7 allows the successive transverse segments 1a, 1B to slide in the axial direction relative to each other, as schematically shown in fig. 4A, and/or to rotate around the radial direction between the pulley sheaves 56, 57, as schematically shown in fig. 4B. It can be seen that by any of these movements, the effective width We of the central opening 5 of the transverse segment 1 available for the ring stack 8 to extend through the opening 5 is reduced, i.e., less than the actual width Wa of the central opening 5 measured perpendicularly between the post portions 11 of the individual transverse segments 1. Thus, the axial play of the ring stack 8 relative to the transverse section 1 is also reduced and/or the width of the ring stack 8 which can be maximally applied in the drive belt 50 is reduced. Both these latter side effects of said play between the protrusions 6 in the cavity 7 are undesirable, since the overall performance in terms of service life and/or load-bearing capacity of the drive belt 50 is thereby adversely affected. At the same time, however, said play is known to be necessary for the proper functioning of the drive belt 50 in the transmission. For example, for allowing the drive belt 50 to accommodate mutual misalignment, i.e., axial offset, between the

pulleys

52, 53 that actually occurs depending on the speed ratio. However, according to the present invention, improvements can be achieved in this respect.

The basis of the invention is that said play between the protrusion 6 and the cavity 7 increases as the protrusion 6 is gradually withdrawn from the cavity 7 due to its conical shape, as shown in fig. 3. Said play has a minimum value when the projections 6 are maximally inserted in the cavities 7, i.e. when successive transverse segments 1 are arranged in parallel in contact with each other. In a first approximation, such a minimum play value increases the distance D from the cone half-angle of the protrusion 6 and the cavity 7 with respect to the distance D between the successive transverse segments 1a, 1b at or near the protrusion 6 and the cavity 7

The mathematical product of the sine of (a). According to the present invention, there is provided,advantageously, by providing the protrusion 6 and the cavity 7 with a reduced cone half-angle with respect to the prior art

To reduce said increase in the minimum play value. It can thus be appreciated that when the projections 6 of successive transverse segments 1a, 1b are not fully inserted into the respective cavities 7, the relative movement between successive transverse segments 1a, 1b in the axial direction is also minimal.

In particular, according to the invention, the conical half-angles of the protuberances 6 and of the cavities 7

Having a value in the range of 3.5 to 6.5 degrees, which is shown on the X-axis of the graph of fig. 5. The straight line in the graph of fig. 5 plots the actual width Wa of the central opening 5 of the transverse segment 1 and its half angle relative to such a cone

Is measured in the same manner as the difference between the effective widths We of (a). The smaller value of this difference Wa-We, i.e. the cone half angle

Is preferred to minimize the occurrence and/or severity of contact between the ring stack 8 and the post portion 11 of the transverse segment 1 during operation of the drive belt 50. However, as schematically illustrated by the curve in the diagram of fig. 5, in a preferred manufacturing process of the fine-blanked transverse section 1, the cone half-angle

Such smaller values of (a) are increasingly difficult to manufacture and a value of about 3 degrees provides a practical lower limit.

The present invention relates to and includes all the features of the appended claims, except for all the details of the foregoing description and accompanying drawings. The recitation in the claims with parentheses does not limit the scope thereof but is merely provided as a non-limiting example of each feature. The claimed features may be applied separately in a given product or a given process as appropriate, but any combination of two or more such features may be applied therein.

The present invention is not limited to the embodiments and/or examples explicitly mentioned herein, but also includes alterations, modifications and practical applications within the reach of a person skilled in the relevant art.

Claims

1. A transverse section (1) for a drive belt (50), the drive belt (50) having a ring stack (8) of a plurality of mutually nested belts and having a plurality of transverse sections (1) which are arranged successively and movably on the ring stack (8), which transverse sections are provided with a central opening (5) for accommodating the ring stack (8) of the drive belt (50), which central opening (5) is bounded on its underside by a base portion (10) of the transverse section (1) and on either side by respective pillar portions (11) of the transverse section (1), which pillar portions (11) extend from the base portion (10) on either side of the central opening (5), and each pillar portion (11) is provided with a conical projection (6) on a front surface (2) of the transverse section (1) and a conical cavity (7) on a rear surface (3) of the transverse section (1), characterized in that, the half angle of the cone of the protuberance (6) and the cavity (7)

Is in the range of 3.5 to 6.5 degrees, preferably equal to 5 degrees.

2. The transverse segment (1) according to claim 1, characterized in that there is a play between the outer diameter of the protrusion (6) and the inner diameter of the cavity (7), the value of said play being in the range 0.015 to 0.05mm, preferably equal to 0.025 mm.

3. Drive belt (50) with a ring stack (8) consisting of a plurality of mutually nested belts and with a plurality of transverse segments (1) according to claim 1 or 2 arranged successively and movably on the ring stack (8), characterized in that a gap exists in the width direction between the two pillar parts (11) of the transverse segment (1) and the ring stack (8), which gap is at most 6% of the width of the ring stack (8).

4. Continuously variable transmission (51) having two variable pulleys, each defining a V-groove of variable width, and the continuously variable transmission (51) having a drive belt (50) according to claim 3 wound on a pulley (52, 53) in the V-groove of the pulley (52, 53), characterized in that during operation of the transmission (51) a maximum axial offset is produced between the V-grooves of the pulleys (52, 53) and a gap in the width direction between the two limbs (11) of the transverse section (1) and the ring stack (8) amounts to at least 1.5 times and at most 2 times the maximum axial offset between the V-grooves of the pulleys (52, 53).