Disk Cooling Arrangement for Toroidal CVT

FIELD

[0001] The present disclosure generally relates to toroidal Continuously

Variable Transmissions (CVTs). More specifically, the present disclosure is concerned with an arrangement for the cooling of the disks of such a CVT.

BACKGROUND

[0002] CVTs are well known transmission mechanisms that can change trough an infinite number of gear ratios between upper and lower limits. Toroidal CVTs, which are also well known, include a disks and roller arrangement where rollers are mounted between an input disk and an output disk to transmit power therebetween. Such CVT transmissions are generally used when transmission ratios have to be finely adjusted.

[0003] In a toroidal CVT, since the rollers are forcefully maintained between the input and output disks while they are rotating, the friction present between the rollers and the disks generate heat. To prevent premature degradation of the transmission, the disk/roller arrangement must be cooled.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] In the appended drawings: [0005] Figure 1 is a perspective view of a CVT provided with a disk cooling arrangement according to a first illustrative embodiment;

[0006] Figure 2 is a front elevation view of the CVT of Figure 1 ;

[0007] Figure 3 is a sectional perspective view taken along line 3-3 of

Figure 2;

[0008] Figure 4 is a sectional perspective taken along line 4-4 of Figure

2;

[0009] Figure 5 is an enlarged portion of a CVT provided with a disk cooling arrangement according to a second illustrative embodiment; and

[0010] Figure 6 is an enlarged portion of a CVT provided with a disk cooling arrangement according to a third illustrative embodiment.

DETAILED DESCRIPTION

[0011] An object is generally to provide an improved toroidal CVT.

More specifically, an object is to provide a toroidal CVT provided with a cooling arrangement for the disks.

[0012] The use of the word "a" or "an" when used in conjunction with the term "comprising" in the claims and/or the specification may mean "one", but it is also consistent with the meaning of "one or more", "at least one", and "one or more than one". Similarly, the word "another" may mean at least a second or more.

[0013] As used in this specification and claim(s), the words "comprising"

(and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "include" and "includes") or "containing" (and any form of containing, such as "contain" and "contains"), are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

[0014] The term "about" is used to indicate that a value includes an inherent variation of error for the device or the method being employed to determine the value.

[0015] It is to be noted that while the expression "toroidal CVT", standing for Continuously Variable Transmission is used herein to describe the illustrated dual-cavity full toroidal CVT, this expression is to be construed herein and in the appended claims as any type of toroidal CVT such as, for example, half- toroidal CVT. It is also to be noted that the expression "CVT" is also to be construed, herein and in the appended claims, as a CVT provided with further elements allowing it to operate as an IVT, standing for Infinitely Variable Transmission, a subset of CVT designs in which the range of ratios of output shaft speed to input shaft speed includes a zero ratio

[0016] The expressions "connected" and "coupled" are interchangeable and should be construed herein and in the appended claims broadly to include any cooperative or passive association between mechanical parts or components. For example, such parts may be assembled together by direct coupling or connection, or indirectly coupled or connected using further parts. The coupling and connection can also be remote, using for example a magnetic field or else.

[0017] The expression "input", without reference to a specific component such as a shaft, should be construed herein and in the appended claims, as including any movable part of an object, an assembly, a system or a mechanism that is used to receive a mechanical work from same or from another assembly, system or mechanism. Similarly, the expression "output" should be construed as including a similar part that is used to transfer a mechanical work.

[0018] The expression "gear ratio" should be construed herein and in the appended claims broadly as meaning the ratio between the speed of rotation at the input of a machine, system or assembly, to that of the output thereof.

[0019] Other objects, advantages and features of the disk cooling arrangement for toroidal CVT will become more apparent upon reading of the following non-restrictive description of illustrative embodiments thereof, given by way of example only with reference to the accompanying drawings.

[0020] Generally stated, illustrative embodiments of the disk cooling arrangement described herein includes a sleeve around the input shaft that is provided with holes and nozzles to project a cooling and lubricating fluid towards both the input and output disks. [0021] Turning now to Figures 1 to 4 of the appended drawings, a CVT

10 including a CVT disk cooling arrangement according to a first illustrative embodiment will be described.

[0022] The toroidal CVT 10 includes two input (or end) disks 12 and 14 connected to an input shaft 16, itself directly or indirectly connected to a prime mover (not shown). An output disk 18, positioned between the input disks 12 and 14, is interconnected therewith via rollers 20. The rollers 20 are so mounted to the shaft 1 6 via an inner sleeve 22 that the angle of the rollers may vary to thereby change the speed ratio between the input disks 12 and the output disk 18. The inner sleeve 22 is prevented from rotating with the input shaft 1 6 by its connection to a rotation blocker 23, which is mounted to a casing (not shown) of the CVT 10.

[0023] Each roller 20 is mounted i) to the inner sleeve 22 via a first ball joint 24 assembly and ii) to a control ring 26 via a second ball joint assembly 28. The casing 30 of the second ball joint assembly 28 is slidably mounted in a longitudinal opening 32 of the control ring 26 of the CVT 10. As it is believed to be well known in the art, the angles of the rollers 20 are modified by rotating the control rings 26 using an actuator (not shown).

[0024] The CVT 10 also includes a disk cooling arrangement including the inner sleeve 22, nozzles 34 and holes within the input shaft 1 6, first and second ball joints 24 and 28, and inlet tubing 36.

[0025] The inner sleeve 22 is mounted coaxially to the input shaft 1 6 thereabout for free rotation of the input shaft 1 6 therein. The inner diameter of the inner sleeve 22 is such as to define an interspace 38 with the input shaft 16. The inlet tubing 36 is connected to the inner sleeve 22 so as to be in fluid communication with the interspace 38. The inlet tubing 36 allows supplying the interspace 38 with cooling and lubricating fluid (see arrow 40). The inner sleeve 22 includes narrower sections 42-44 near its longitudinal ends to prevent a significant quantity of the cooling fluid from exiting the interspace 38 from both its longitudinal ends.

[0026] The inner sleeve 22 includes a series of radial holes 46 that are generally centered with the output disk 18. The inner sleeve 22 further includes a center groove 48 that forms an interspace 50 with the center disk-mounting element 49. The center disk-mounting element 49 is provided around the inner sleeve 22 for receiving the output disk 18 thereon via a bearing 53. Since the element 49 is non-rotating except during a ratio change, it may be viewed as part of the inner sleeve 22. The mounting element 49 includes a series of radial holes 52 (see Figure 4) that are adjacent the lateral surfaces of the output disk 18. The radial holes 52 may be viewed as radial cooling and lubricating fluid injectors. Together the radial holes 46, interspace 50 and holes 52 define fluid passages for the cooling and lubricating fluid between the interspace 38 and the roller cavities between the input and output disks 12-14 and 18. More specifically, these fluid passages allow projecting cooling fluid on both lateral surfaces of the output disk 18 (see arrows 54 in Figure 4). Indeed, when the rollers 20 are close to the center of the disk 18, the fluid will be deflected by the rollers and projected on the surface of the output disk 18 close to the point of contact between the roller and the disk to cool the disk surface at the point of contact.

[0027] Returning to Figure 3, each of the two cavities of the CVT 10 includes a cylindrical nozzle 34, mounted to the inner sleeve 22 diametrically opposite one of the first ball joint 24. The nozzle 34 includes a radial conduit 56 that is in fluid communication with the interspace 38 and a transversal hole 58 that extends from the conduit 56 to the outside of the nozzle 34 towards a respective input disk 12 or 14. More specifically, the transversal hole 58 aims towards the inner edge of the toroidal portion of the disk 12 or 14 (see arrow 60 in Figure 3).

[0028] It is to be noted that one of the nozzle 34 is associated with the inlet tubing 36 to receive its cooling fluid directly therefrom. The radial conduit of this nozzle 34 is therefore larger to accommodate this larger flow of cooling fluid.

[0029] In addition to the disk cooling arrangement described hereinabove, the overall cooling arrangement of the CVT 10 further includes a channel 66 that extends from the interspace 38 through the first ball joint 24 that allows channeling cooling fluid from the interspace 38 towards the ball bearings 68 of the rollers 20 (see arrows 70). It is also to be noted that a portion of the cooling fluid passing through the channel 66 may be projected onto the disks 12, 14 and 18 via the rotation of the rollers 20.

[0030] One skilled in the art will now understand that the interspace 38 acts as a manifold to distribute the cooling fluid from an external source (not shown) to the various channels, nozzle 34 and ultimately to the disks 12, 14 and 18 and rollers 20 under a pressure applied by a pump (not shown) external or internal to the CVT 10. The cooling fluid can therefore be cooled externally from the working cavities of the CVT 10 using a conventional cooling mechanism (also not shown). [0031] It is to be noted that the cooling fluid source, the pump and the cooling mechanism could be integrated to the casing of the CVT 10 to yield a self- contained system.

[0032] One skilled in the art will understand that, for concision and clarity purposes, the CVT 10 is schematically illustrated in the appended drawings and that other elements (not shown) are required for the adequate operation of the CVT.

[0033] While the CVT 10 has been described as having two input disks

12, 14 and one output disk 18, this could be reversed.

[0034] Turning now briefly to Figure 5 of the appended drawings, a nozzle 134, part of a disk cooling arrangement according to a second illustrative embodiment will be described. As can be seen from this figure, the radial conduit 158 of the nozzle 134 includes a tube that brings the cooling fluid closer to the disk 12 before being projected thereonto. Accordingly, the flow of cooling fluid is directed more precisely onto the disk 12.

[0035] Turning now briefly to Figure 6 of the appended drawings, a nozzle 234, part of a disk cooling arrangement according to a third illustrative embodiment, will be described. As can be seen from this figure, the nozzle 234 includes four (4) radial conduits 258 (only three shown) that are smaller than the replaced conduit 58 of Figure 3. Accordingly, the flow of cooling fluid ejected from the smaller radial conduits 258 is more laminar and is therefore directed more precisely onto the disk 12. [0036] It is to be understood that the disk cooling arrangement for toroidal CVT is not limited in its application to the details of construction and parts illustrated in the accompanying drawings and described hereinabove. The disk cooling arrangement for toroidal CVT is capable of other embodiments and of being practiced in various ways. It is also to be understood that the phraseology or terminology used herein is for the purpose of description and not limitation. Hence, although the disk cooling arrangement for toroidal CVT has been described hereinabove by way of illustrative embodiments thereof, it can be modified, without departing from the spirit, scope and nature thereof.

[0037] The following numbered clauses are provided as further description.

[0038] 1 . A cooling arrangement to cool the center and end disks of a dual-cavity toroidal CVT comprising: a sleeve mounted to an input shaft of the toroidal CVT; the sleeve defining a closed interspace with the input shaft; the sleeve including an opening for receiving a cooling fluid; the sleeve having two series of radial holes defining cooling fluid injectors, each registered with a corresponding lateral surface of the center disk for injecting the cooling fluid onto the center disk on both lateral surfaces thereof ; and two nozzles, each mounted to the sleeve; each nozzle being in fluid communication with closed interspace and having an outlet oriented towards a respective one of the end disks so as to project cooling fluid thereon.

[0039] 2. The cooling arrangement as recited in clause 1 , further comprising an inlet tubing in fluid communication with the cooling fluid receiving opening of the sleeve.

[0040] 3. The cooling arrangement as recited in clause 2, wherein the inlet tubing in associated with one of the two nozzles.

[0041] 4. The cooling arrangement as recited in any of the preceding clauses, wherein the sleeve includes a center disk-mounting element including the two series of radial holes defining cooling fluid injectors in the center disk mounting element.

[0042] 5. The cooling arrangement as recited in any of the preceding clauses, wherein each of the two nozzles includes a radial conduit in fluid communication with the closed interspace and a lateral hole in fluid communication with the radial conduit and facing a respective one of the end disks.

[0043] 6. The cooling arrangement as recited in clause 5, wherein the lateral hole of the nozzle faces an inner edge of a toroidal portion of the respective one of the end disks.

[0044] 7. The cooling arrangement as recited in clause 5, wherein the lateral hole of the nozzle includes an extension tube facing a respective one of the end disks.

[0045] 8. The cooling arrangement as recited in clause 5, wherein the lateral hole includes four lateral holes. [0046] 9. The cooling arrangement as recited in any of the preceding clauses further including rollers provided between the center and end disks, each roller being connected to the sleeve via a respective ball joint assembly including a ball bearing to allow the roller to rotate thereon, each ball joint assembly including a channel extending from the interspace therethrough to allow cooling fluid from the interspace towards the ball bearing.

[0047] 10. The cooling arrangement as recited in clause 9, wherein the nozzles are mounted to the sleeve diametrically opposite a corresponding roller- mounting ball joint.

[0048] 1 1 . A cooling arrangement to cool the center and end disks of a dual-cavity toroidal CVT comprising: means to receive a cooling fluid; the cooling fluid receiving means including cooling fluid injectors, each registered with a corresponding lateral surface of the center disk for injecting the cooling fluid onto the center disk on both lateral surfaces thereof ; and two nozzles in communication with the cooling fluid receiving means and having an outlet oriented towards a respective one of the end disks so as to project cooling fluid thereon.