NL1040570C2 - Method for assembling a drive belt with different types of transverse members for a continuously variable transmission and a thus assembled drive belt. - Google Patents

Abstract

The invention relates to a transmission belt (3) and assembly method, wherein transmission with an annular bearing (31) and variable thickness of the adjacent transverse rod (32), the thickness along the transmission belt (3) are directional to measuring size. According to the invention, wherein the same horizontal rod (32) is provided at least two serial element (RS1; RS2), a tail part (RS1) cover according to two types or multiple kinds of the 03-type (32-I and 32-II) transverse rod (32) at least two preset (sequences cylinder, II) and a assembly, wherein two types or various of the 03-type (32-I and 32-II) of the transverse rod (32) T32-I and T32-II) is at least in different and are thickness are.

Description

METHOD FOR ASSEMBLING A DRIVE BELT WITH DIFFERENT TYPES OF TRANSVERSE MEMBERS FOR A CONTINUOUSLY VARIABLE TRANSMISSION AND A THUS ASSEMBLED DRIVE BELT

The present invention relates to a drive belt for a continuously variable transmission, which drive belt is in particular destined to be arranged around two pulleys of the transmission and which drive belt comprises a plurality of discrete transverse elements, i.e. transverse members for contacting the transmission pulleys, as well as one or more endless, i.e. annular, carriers for carrying and guiding the transverse members in the transmission. The present type of drive belt is also referred as a pushbelt.

The endless carrier of the drive belt is typically composed of a plurality of mutually nested, continuous flexible metal bands and is also known as a ring set. The endless carrier is at least partly inserted in a recess provided in the transverse members. In case the drive belt comprises only one endless carrier, such carrier is typically mounted in a central recess of the transverse members that opens towards the radial outside of the drive belt. However, usually the drive belt is provided with at least two endless carriers that are each mounted in a respective one of two recesses of the transverse members, which recesses then open towards a respective axial or lateral side of the transverse members, i.e. of the drive belt.

The transverse members of the drive belt are slidingly arranged along the circumference of the endless carrier or carriers in a virtually continuous row, such that these members are able to transmit forces that are related to a movement of the drive belt. The transverse members have two main body surfaces that, at least partly, extend substantially parallel with respect to each other and that are separated from each other over the (local) thickness of the transverse member by a circumferential side surface thereof. As seen along the circumference of the carrier, the transverse members have a comparatively small dimension, i.e. thickness, such that a several hundreds thereof are present in the drive belt. Adjoining transverse members are designed to be able to tilt relative to one another, such that the belt is able to follow a curved trajectory. To accommodate and control such relative tilting, one of the two main body surfaces of the two adjoining transverse members in the drive belt that are in mutual contact is provided with a (so-called) rocking edge in the form of an axially and radially extending section of the respective main body surface(s) that is convexly curved in radial direction. In this respect, it is noted that the radial direction is defined relative to the drive belt when it is placed in a circular posture.

Parts of the side surface of the transverse members, which parts are predominantly oriented in the axial direction, i.e. widthwise, are corrugated and are intended for frictionally contacting the transmission pulleys, in particular by being clamped widthwise between two conical sheaves of such pulleys. The friction contact between the transverse members and the conical pulley sheaves allows a force to be transferred there between, such that the drive belt can transmit a drive torque and rotational movement from one transmission pulley to the other.

Although, typically, the majority of the transverse members of a drive belt are identically shaped, it is also well-known, for example from the United States patent publication US-A-2006/0079361, to include transverse members having a mutually different thickness into a single drive belt in order to attenuate the noise that is caused by the transverse members successively impacting the pulleys during operation of the transmission, at least relative to a standard belt including transverse members having mutually identical thickness only. More specifically, according to US-A-2006/0079361, a plurality of drive belts are randomly assembled from both first and second transverse members that differ only by their thickness and the noise that is generated during operation of the transmission is measured for all of these drive belts. In relation to the drive belt that is associated with the least noise being generated by the transmission, the sequence of the said first and second transverse members is determined and the mass production of the drive belt takes place according to such determined sequence.

Another example of the same principle of applying transverse members of different thickness in the drive belt is given by the US patent application No. 8104159. According to US8104159 the total number of transverse members in the drive belt is split into two or more consecutive groups of transverse members, with each such group being defined by a specific ratio of thinner versus thicker transverse members that are randomly mixed.

Although these known drive belt assembly methods of randomizing the thickness of the transverse members of the drive belt can indeed be successful in reducing transmission noise, they are less suited for mass producing the drive belt. In particular, these known methods do not provide for any flexibility in terms of the ratio between the thinner versus the thicker transverse members between the produced drive belts, nor is it possible to influence the length of the complete row of transverse members that is incorporated in the drive belt, e.g. to compensate manufacturing tolerances in the thickness of the individual transverse member and/or in the circumference length of the endless carrier.

It is an object of the present disclosure to provide for a drive belt assembly method that is favorable in terms of the said transmission noise that is produced thereby, but that also favors the mass production of the drive belt. According to the present disclosure, such object is achieved with the drive belt assembly method in accordance with the claim 1 hereinafter. In such novel drive belt assembly method the complete row of transverse members included in the drive belt is provided on the endless carrier of the drive belt with at least one row part or section including two or more types of transverse members that differ at least in terms of their thickness according to one at least two predetermined sequences, with the numbers of transverse members of a specific type being different between the at least two predetermined sequences. It being noted that the said at least two predetermined sequences of transverse members of the said at least one row section are (pre-)defined such that only a minimal noise is generated during operation of the transmission, for example by empirical means, as described in US-A-2006/ 0079361, or by (computer) modeling.

In mass production, this novel assembly method thus allows a particular predetermined sequence to be chosen from between the said at least two predetermined sequences, i.e. allows the number of transverse members of the respective types incorporated in the drive belt to be influenced. In particular, the predetermined sequence is chosen that incorporates the said types of transverse members according to a ratio that is closest to a ratio of these types of transverse members that is actually available for the assembly of the drive belt. In other words, the numbers of transverse members of a specific type or thickness that are used in a specific drive belt can be varied between the produced drive belt. Such flexibility in production is advantageous, because it allows for likewise flexible (pre-)production numbers of the transverse members of the different thickness types.

In a preferred embodiment of the above, novel assembly method, the complete row of transverse members includes a second row section is assembled from transverse members of any type or thickness, such that the numbers of transverse members of a specific type or thickness in the second row section can be varied between the produced drive belts. This second row section favorably allows the length of the complete row of transverse elements to be accurately adapted to the circumference length of the endless carrier. This latter feature is normally desired to compensate manufacturing tolerances in the thickness of the individual transverse member and/or the in the circumference length of the endless carrier.

This latter, preferred embodiment of the novel assembly method and the drive belts that are obtained thereby rely, amongst others, on the observation that a noticeable noise attenuation effect of the predetermined sequence of two or more types of transverse members can already be obtained if such predetermined sequence includes only a part of the complete row of transverse members included in the drive belt. In this respect, it has been determined that such predetermined sequence, i.e. the said one row section, should preferably include 95% of the total number of transverse members in the drive belt in order to combine the highest attainable noise attenuation effect by the said one row section with a second row section that is long enough to allow the length of the complete row of transverse elements to be adapted to the circumference length of the endless carrier.

More specifically in this latter, preferred embodiment of the novel assembly method, the second row section is initially assembled from transverse members of one single type, i.e. transverse members having the same thickness, whereas in the final step of the novel assembly method, these transverse members are replaced by transverse members of another one single type, i.e. thickness. These latter features greatly simplify the final step of the novel assembly method, since a direct relationship exists between the number of transverse members thus replaced and the reduction of the clearance gap that is attained thereby. However, in this latter method it can occur that the second row section includes only or primarily transverse members of one single type, i.e. of one single thickness, which is likely to increase the transmission noise contrary to what is presently aimed for. Therefore, in this specific case the second row section preferably include up to 98% of the total number of transverse members in the drive belt.

The background for the above insights and embodiments are explained hereinafter with reference to the accompanying drawing figures. In the drawing figures equal reference signs indicate equal or similar structures and/or parts.

Figure 1 provides a schematic perspective view of the continuously variable transmission with a drive belt running over two pulleys, which drive belt includes an endless carrier, as well as a number of transverse members that are arranged in a row along the circumference of the endless carrier.

Figure 2 shows a cross section of the known drive belt viewed in the circumference direction thereof.

Figure 3 provides a width-wise oriented view of a transverse member of the known drive belt.

Figure 4 is a first schematic representation of a row of transverse members of the drive belt in accordance with the present disclosure, which row includes transverse members of two types, each type having a different size in terms of a respective thickness thereof, and which row is divided into two sections that are mutually distinguishable by the distribution of these different types of transverse members.

Figure 5 is a second schematic representation of a row of transverse members of the drive belt in accordance with the present disclosure.

Figure 6 is a third schematic representation of a row of transverse members of the drive belt in accordance with the present disclosure.

The schematic illustration of a continuously variable transmission in Figure 1 shows a drive belt 3 that runs over two pulleys 1, 2 and that includes a closed, i.e. endless carrier 31 and an essentially contiguous row of transverse members 32 that are mounted on the carrier 31, arranged along the circumference thereof. In the illustrated position, the upper pulley 1 rotates more quickly than the lower pulley 2. By changing the distance between the two conical sheaves 4, 5 of each pulley 1, 2, the so-called running radius R of the drive belt 3 on the respective pulleys 1, 2 can be changed and, as a result, the rotational speed ratio i between the two pulleys 1, 2 can be varied. This is a known manner of varying a difference in rotational speed between an input shaft 6 and an output shaft 7 of the transmission.

In Figure 2, the drive belt 3 is shown in a cross section thereof facing in the circumference or length direction L of the belt 3, i.e. facing in a direction perpendicular to the axial or width W direction and the radial or height H direction of the drive belt 3. This Figure 2 shows the presence of two endless carriers 31 that are shown in cross-section and that carry and guide the transverse members 32 of the drive belt 3, whereof one transverse member 32 is shown in front elevation in Figure 2.

The transverse members 32 and the endless carriers 31 of the drive belt 3 are typically made of metal, usually steel. The transverse members 32 take-up a clamping force exerted between the sheaves 4, 5 of each pulley 1, 2 via pulley contact faces 37 that are provided on either axial side thereof. These pulley contact faces 37 are mutually diverging in radial outward direction, whereby the angle that is defined there between essentially matches a V-angle defined between the two sheaves 4, 5 of each pulley 1, 2. The transverse members 32 are able to move, i.e. slide along the endless carriers 31 in the said circumference direction L, so that when a force is transmitted between the transmission pulleys 1, 2, this force is transmitted by the transverse members 32 pressing against one another and pushing each other forward in a direction of rotation of the drive belt 3 and the pulleys 1, 2. In this particular exemplary embodiment of the drive belt 3, the endless carriers 31 thereof are composed of five individual endless bands each, which endless bands are mutually concentrically nested to form the endless carrier 31. In practice, the endless carriers 31 often comprise more than five endless bands, e.g. up to twelve or more.

The transverse member 32, which is also shown in a side view in Figure 3, is provided with two cut-outs 33 located opposite one another and opening widthwise, towards opposite sides of the transverse member 32. Each cut-out 33 accommodates a respective one of the two endless carriers 31. A first or base portion 34 of the transverse member 32 thus is located radially inward of the endless carriers 31, a second or middle portion 35 of the transverse member 32 is situated in between the endless carriers 31 and a third or top portion 36 of the transverse member 32 is located radially outward of the endless carriers 31. The radially inner side of a respective cut-out 33 is delimited by a so-called bearing surface 42 of the base portion 34 of the transverse member 32, which bearing surface 42 faces radially outwards in the general direction of the top portion 36. This bearing surface 42 contacts the radial inside of the endless carrier 31, especially in the parts of the drive belt 3 that are clamped between the sheaves 4, 5 of the transmission pulleys 1, 2. A first or rear surface 38 of the two main body surfaces 38, 39 of transverse member 32 that face in mutually opposite circumference directions L, is essentially flat. The other or front main body surface 39 of the transverse member 32 is provided with a so-called rocking edge 18 that forms, in the radial direction H, the transition between an upper part of the front surface 39, extending essentially in parallel with its rear surface 38, and a lower part thereof that is slanted such that it extends towards the rear surface 38. In Figure 2 the rocking edge 18 is indicated only schematically by way of a single line, however, in practice the rocking edge 18 is mostly provided in the form of a part of the said front surface 39 that is convexly curved in the radial direction H and that is straight and flat in the axial direction W. Thus, an upper part of the transverse member 32 that is located radially outward from/above the rocking edge 18 is provided with an essentially constant dimension between the main body surfaces 38, 39 thereof, i.e. as seen in the circumference direction L, which dimension is referred to as the thickness T32 of the transverse member 32. Furthermore, it is common practice to provide with a protrusion 40 and a recess 41 in the top portion 36 of the transverse member 32, however on opposite sides thereof. In the drive belt 3, this protrusion 40 and recess 41 engage one another between adjacent transverse members 32 in the row of transverse members 32. Hereby, the adjacent transverse members 32 are aligned relative to one another perpendicular to the said circumference direction L.

Typically, the said thickness T32 is the same for virtually all, i.e. for more than 98%, of the transverse members 32 of the drive belt 3, with a value in the range from 1 to 2 millimeter. A typical value for the said thickness T32 of the transverse members 32 is 1.5 mm and a typical value for the said circumference direction L is 0.7 meter.

During operation of the transmission, i.e. during the rotation of the pulleys 1, 2 and the drive belt 3, the transverse members 32 thereof successively enter between the pulley discs 4, 5, by which repeated contact between the transverse members 32 and the pulleys discs 4, 5 vibrations are generated, which vibrations may, in turn, generate noise that is audible by the occupants of the vehicle wherein the transmission is applied. It is a known design principle to make the said repeated contact less regular by applying transverse members 32 of mutually different thicknesses in the row of transverse members 32 of the drive belt 3. For example, in this respect it is known from EP-A-0305023 to apply two types of transverse members 32 of mutually different thickness in a random distribution in the said row of transverse members 32 of the drive belt 3. US-A-2006/ 0079361 goes one step further by checking several of such random distributions in terms of the said noise level and to apply in mass production of the drive belt 3 only that distribution, i.e. that specific sequence of the sequence transverse members 32 of certain thickness that is associated with the lowest noise level during operation of the transmission. According to the present disclosure, the latter approach of US-A-2006/ 0079361, although favorable over EP-A-0305023 in terms of consistency in mass production, does not provide any flexibility in terms of the relative use of the transverse members 32 of different thickness, nor is it possible to influence the length of the complete row of transverse members 32 that is incorporated in the drive belt 3.

In order to overcome these limitations of the known art, it is presently suggested -in a preferred embodiment- to provide the complete row of transverse members 32 of in the drive belt 2 in at least two row parts or sections RSI and RS2, whereof one row section RSI is provided on the endless carrier 31 of the drive belt 3 according to a predetermined sequence of two or more types of transverse members 32-1, 32-11 that differ at least in terms of the thickness T32-I, T32-II thereof and whereof the other one row section RS2 is assembled by filling the remaining circumference length of the endless carrier 31 with transverse members 32 of any type 32-1, 32-11, as is schematically illustrated in figure 4 with the said other one row section RS2 including only one type of transverse elements 32-1, i.e. of one thickness T32-I only.

It is noted that this Figure 4 (and later ones) serves to illustrate the basic (design) principles of the present disclosure, but does not provide a true representation of the drive belt 3 or of the row of transverse members 32 thereof, neither in term of the number of transverse members 32 included therein, nor in terms of the absolute or relative size and shape of these transverse members 32.

The predetermined sequence of transverse members 32 in the said one row section RSI is of course (pre-)defined such that the transmission produces minimal noise during operation, however, between the consecutively produced drive belts 3 it is selected from at least two predetermined sequences I or II (see Figure 4), with the numbers of transverse members 32 of a specific type 32-1, 32-11 being different between the at least two predetermined sequences I and II.

In mass production, this novel assembly method thus allows a particular predetermined sequence I or II to be chosen freely, i.e. allows the number of transverse members 32 of the respective types 32-1, 32-11 incorporated in the drive belt 3 to be influenced. In particular, the predetermined sequence I or II is chosen that incorporates the said types of transverse members 32-1, 32-11 according to a ratio that is closest to a ratio of these types of transverse members 32-1, 32-11 that is available for the assembly of the drive belts 3. This flexibility in production is advantageous, because it allows for likewise flexible (pre-)production numbers of the transverse members 32 of the different thickness types 32-1,32-11.

As is also shown in Figure 4, the complete row of transverse members 32 preferably includes a second row section RS2 that is assembled from transverse element 32 of one and the same type 32-1, 32-11; Here type 32-1 with the lesser T32-I of the two available thicknesses T32-I, T32-II. This second row section RS2 favorably allows the length of the complete row of transverse elements 32 to be accurately adapted to the circumference length ECL of the endless carrier 31, as is illustrated in more detail with reference to Figures 5 and 6. This latter feature is normally desired to compensate manufacturing tolerances in the thickness of the individual transverse member 32 and/or the in the circumference length of the endless carrier 31. More specifically in this latter, preferred embodiment of the novel assembly method, after the second row section RS2 has initially been assembled from transverse members 32 of the (in this example) thinner type 32-1, a part of all of the transverse members 32 of the second row section RS2 are replaced by transverse members 32 of the (in this example) thicker type 32-11 to extend the length of this second row section RS2, in particular such that the total length of the complete row of transverse element 32 of the drive belt 3, i.e. RSI plus RS2, closely matches the circumference length ECL of the endless carrier 31.

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.

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.

Claims (5)

Method for assembling a drive belt (3) with an endless support (31) and a series of successive transverse elements (32) arranged on the support (31), each provided with a front surface (39) and with a rear surface ( 38) between which the transverse element (32) extends in thickness direction and from side surfaces (37) between which the transverse element (32) extends in width direction, which side surfaces (37) are intended for contact with pulley discs (4, 5) of pulleys (1, 2) of a transmission in which the drive belt (3) can be used, of which transverse elements (32) at least two types (32-1, 32-11) with a mutually different dimension in thickness direction (T32-I; T32-II) ) are included in the drive belt (3), characterized in that at least a part (RS1) of the series of transverse elements (32) in the drive belt (3) is built up of transverse elements (32) according to one of two or more predetermined sequences (I, II) of said types (32-I; 32-11) of transverse elements (32). Method for assembling a drive belt (3) according to claim 1, characterized in that the series of transverse elements (32) thereof comprises, in addition to the first-mentioned part (RS1) and second part (RS2), which second series part ( RS2) is composed of transverse elements (32) of only one of the mentioned types (32-1; 32-11) thereof. Method for assembling a drive belt (3) according to claim 1 or 2, characterized in that the first-mentioned part (RS1) of the series of transverse elements (32) of the drive belt (3) is at least 95% and at least 98% of all transverse elements (32) of the drive belt (3). Method for assembling a drive belt (3) according to claim 2 or 3, wherein, after the series of transverse elements (32) of the drive belt (3) is initially assembled, a length difference between a circumferential length of the endless support (31) ) and a combined length of said series parts (RS1; RS2) of the series of cross elements (32) is determined, and in which subsequently a number of cross elements (32) is removed from said second series part (RS2) and is replaced by a number of transverse elements (32) of a different type (32-1; 32-11) than said one type (32-1; 32-11) from which the second series part (RS2) is initially composed. 5. A plurality of assembled drive belts (3), each with an endless support (31) and a series of successive transverse elements (32) arranged on the support (31), each provided with a front surface (39) and a rear surface (39) 38) between which the transverse element (32) extends in thickness direction and from side surfaces (37) between which the transverse element (32) extends in width direction, which side surfaces (37) are intended for contact with pulley discs (4, 5) of pulleys (1, 2) of a transmission in which the drive belt (3) can be used, of which transverse elements (32) at least two types (32-1, 32-11) with a mutually different dimension in thickness direction (T32-I; T32-II) ) are included in the drive belt (3), characterized in that the series of transverse elements (32) of the plurality of drive belts (3) each comprise a series part (RS1) which according to at least two equal sequences (I, II) of said types (32-1; 32-11) of transverse elements (32) is constructed.