Continually Variable Transmission Provided with An Electric

Machine

FIELD

[0001] The present disclosure generally relates to Continuously

Variable Transmissions (CVTs). More specifically, the present disclosure is concerned with a CVT provided with a pressure-applying mechanism to which is associated the rotor of an electric machine.

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 disk and roller arrangement that transmits power between the disks, wherein one disk is the input and the other disk is the output. Such a transmission is used when transmission ratios have to be finely adjusted. A pressure-applying mechanism is generally used to apply longitudinal pressure on the disks and the rollers to prevent them from slipping during use.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] In the appended drawings:

[0004] Figure 1 is a perspective view of a dual-cavity Continually

Variable Transmission provided with an electric machine according to a first illustrative embodiment, shown from the input side and shown without a casing; [0005] Figure 2 is a perspective view of the Continually Variable

Transmission of Figure 1 , shown from the output side;

[0006] Figure 3 is a longitudinal sectional view taken along line 3-3 of

Figure 1 , shown with a casing;

[0007] Figure 4 is a sectional view taken along line 4-4 of Figure 4;

[0008] Figure 5 is a perspective view of a dual-cavity Continually

Variable Transmission provided with an electric machine according to a second illustrative embodiment, shown from the input side and shown without a casing;

[0009] Figure 6 is a perspective view of the Continually Variable

Transmission of Figure 5, shown from the output side;

[0010] Figure 7 is a longitudinal sectional view taken along line 7-7 of

Figure 5, shown with a casing;

[0011] Figure 8 is a sectional view taken along line 8-8 of Figure 7;

[0012] Figure 9 is a perspective view of a dual-cavity Continually

Variable Transmission provided with an electric machine according to a third illustrative embodiment, shown from the input side and shown without a casing;

[0013] Figure 10 is a longitudinal sectional view taken along line 10-

10 of Figure 9, shown with a casing;

[0014] Figure 11 is a sectional view taken along line 11-11 of Figure

10; [0015] Figure 12 is a longitudinal sectional view of a dual-cavity

Continually Variable Transmission provided with an electric machine according to a fourth illustrative embodiment, and

[0016] Figure 13 is a longitudinal sectional view of a single-cavity

Continually Variable Transmission provided with an electric machine according to a fifth illustrative embodiment.

DETAILED DESCRIPTION

[0017] An object is generally to provide a Continually Variable

Transmission provided with an electric machine.

[0018] More specifically, according to an illustrative embodiment, there is provided a continuously variable transmission including: a casing having an internal surface; a rotatable input associated with a driving disk; a rotatable output associated with a driven disk; rollers provided between the driving and driven disks; and an electric machine having a stator associated with the internal surface of the casing and a rotor associated with one of the driving and driven disks.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] It is to be noted that the expression “prime mover” is to be construed herein and in the appended claims as an internal combustion engine a turbine engine, or any other mechanical power production element or assembly.

[0023] It is to be noted that while the expression “CVT”, standing for

Continuously Variable Transmission is to be construed, herein and in the appended claims as any type of Continuously variable transmission that is provided with a pressure-applying mechanism, including, amongst others dual cavity full toroidal CVT, half-toroidal CVT and single-cavity toroidal CVT.

[0024] The expressions “connected” and “coupled” are interchangeable and should be construed herein and in the appended claims broadly so as 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. [0025] 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.

[0026] Other objects, advantages and features of the Continually

Variable Transmission provided with an electric machine 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.

[0027] Generally stated, illustrative embodiments describe full toroidal

CVTs provided with a pressure applying mechanism that apply longitudinal pressure to compress the disks and the rollers of the toroidal CVT to prevent slipping during use. The external surface of the pressure-applying mechanism supports the rotor elements of an electric machine while the internal surface of a casing enclosing the CVT supports the stator elements of the electric machine.

[0028] Turning now more specifically to Figures 1 to 4 of the appended drawings, a CVT provided with an electric machine 10 according to a first illustrative embodiment will be described.

[0029] The CVT 10 an input shaft 12 for receiving power from a prime mover (not shown), two driving disks 14, 16 provided with respective toroidal surfaces 18, 20, a driven disk 22 provided with two opposite toroidal surfaces 24, 26 respectively facing the toroidal surfaces 18 and 20 and a drum assembly 28 associated with the driven disk 22 and including an output shaft 30 transmitting the variable speed power output. [0030] Positioned between the driving disks 14 and 16 and the driven disk 22 are drive rollers 32, 34 that are suitable for transferring rotational motion from the driving disks 14 and 16 to the driven disk 22. More specifically, the drive rollers 32, 34 rotate between the toroidal surfaces of the driving disks 14, 16 and the driven disk 22, such that by changing the angle of the drive rollers 32, 34 in relation to the driving disks 14, 16 and the driven disks 22, there is a ratio change between the speed of rotation of the driving disks 14, 16 and the speed of rotation of the driven disk 22, thereby providing a continuously variable transmission.

[0031] The input shaft 12 is fixedly connected to the driving disks 14 and 16 and to a pressure-applying mechanism 36 that is positioned next to the driving disk 14 to exert a longitudinal compression force thereonto. More specifically, the pressure-applying mechanism 36 is used to compress the disks and the rollers together, to prevent slipping therebetween so that torque may adequately be transferred from the input to the output.

[0032] The pressure-applying mechanism 36 includes a pressure applying element 37, a secondary element in the form of a shaft-driving element 39, a plurality of ball bearings 41 provided between the pressure applying element 37 and the shaft driving element 39. The facing surfaces of both the pressure-applying and shaft-driving elements 37 and 39 are provided with ramps (not shown) receiving the ball bearings 41 so that a minute rotational movement between the pressure-applying element 37 and the shaft-driving element 39 causes a longitudinal force compressing the disks and rollers together.

[0033] The pressure-applying mechanism 36 also includes a cover 43 integral with the input shaft 12 to rotate therewith. The cover 43 defines an external surface of the mechanism 36. [0034] As the driving disks 14 and 16 rotate, they cause the drive rollers 32, 34 to rotate, which in turn causes the driven disk 22 to rotate. The driven disk 22 rotates about the same axis as the driving disks 14, 16 and the input shaft 12.

[0035] As will be understood to one skilled in the art, the use of a drum assembly such as 28 allows the input shaft 12 and the output shaft 30 to be colinear without the use of a gear arrangement.

[0036] The drum assembly 28 includes a generally bell-shaped drum

38 mounted to the output shaft 30 via fasteners 40. As can be better seen from Figure 1 , the free end of the drum 38 includes crenellations that connect with the peripheral surface of the output disk 22. Accordingly, the drum 38 rotates with the output disk 22.

[0037] As will be obvious to one skilled in the art, a casing is required to protect and contain the various elements of the CVT 10. While this casing is not shown in Figures 1 and 2, a schematically illustrated casing 44 is shown in Figures 3 and 4. Indeed, casings generally have a more complex form than schematically shown herein. For the purpose of the present disclosure, suffice to show that the casing 44 includes in internal surface 46 and schematically illustrated bearings to support the input and output.

[0038] It will be apparent to one skilled in the art that many mechanical elements required for the adequate operation of the CVT 10 have been omitted from the enclosed drawings and the above description. These elements were not material to the present disclosure and were omitted for clarity and concision purposes. [0039] An electric machine is interposed between the cover 43 of the pressure-applying mechanism 36 and the internal surface 46 of the casing 44.

[0040] Generally stated, the electric machine includes a rotor 54 associated with the pressure-applying mechanism 36 and a stator 52 associated with the internal surface 46 of the casing.

[0041] More specifically, the cover 43 of the pressure-applying mechanism 36 includes a radially outwardly extending support 48 having a cylindrical external surface 50. The rotor 54 includes a plurality of permanent magnets 62 (see Figure 4) mounted to the cylindrical external surface 50.

[0042] As can be better seen from Figure 4 of the appended drawings, the stator 52 includes a stack of laminations each provided with internally facing tooth 56 defining slots 58 therebetween. The slots 58 are conventionally filled with coils of wires 60.

[0043] It is believed to be within the skills of one knowledgeable in the art to determine the number, size and spacing of the slots 58 and the number, size, shape, composition and spacing of the permanent magnets 62 to yield an electric machine having the desired characteristics.

[0044] The rotor 54 has been shown as having magnets 62 directly mounted to the cylindrical external surface 50 of the support 48, which is made of a metallic ferromagnetic material. Should the support 48 be made of a non- metallic or non-ferromagnetic material, a base (not shown) made of such material could be interposed between the external surface of the support and the magnets. [0045] Turning now to Figures 5 to 8 of the appended drawings, a

CVT provided with an electric machine 100 according to a second illustrative embodiment will be described. Since the CVT 100 is very similar to the CVT 10 of Figures 1 to 4, only the differences therebetween will be discussed hereinbelow for concision purpose.

[0046] Generally stated, in the CVT 100, the orientation of the electric machine has been reversed with respect to the electric machine of the CVT 10 discussed hereinabove. Indeed, the casing 106 of the CVT 100 has been enlarged to allow the electric machine to be installed radially aligned with one of the disks of the CVT 100 as can be better seen from Figure 7. Again, the stator 104 of the electric machine is mounted to the inner surface of the casing 106.

[0047] An outwardly extending support 102 is part of the cover of the pressure-applying mechanism and receives the rotor 108 of the electric machine.

[0048] Turning to Figures 9 to 11 of the appended drawings, a CVT provided with an electric machine 200 according to a third illustrative embodiment will be described. Since the CVT 200 is very similar to the CVT 10 of Figures 1 to 4, only the differences therebetween will be discussed hereinbelow for concision purpose.

[0049] Generally stated, the electric machine mounted to the CVT 200 is smaller than the previously discussed electric machines. As can be better seen from Figure 10, the casing 204 of the CVT 200 includes an inwardly extending support 206 to which the stator 208 of the electric machine is mounted. The cover 202 of the pressure-applying mechanism directly supports the rotor [0050] Turning now to Figure 12 of the appended drawings, a CVT provided with an electric machine 300 according to a fourth illustrative embodiment will be described. Since the CVT 300 is very similar to the CVT 200 of Figures 9 to 11 , only the differences therebetween will be discussed hereinbelow for concision purpose.

[0051] Generally stated, the main difference between the CVT 300 and the CVT 200 is that the input shaft 202 goes through the CVT 300 and exits coaxially with the output shaft 204 to yield a PTO (Power-Take-Off) output 206.

[0052] Since the electric machine 208 is associated with the pressure- applying mechanism 210 that is splined onto the input shaft 202, it is possible to power the PTO output 206 with the electric machine 208.

[0053] One skilled in the art will understand that since the input disks

212 and 214 are also splined onto the input shaft 202, the output 204 can also be powered by the electric machine 208.

[0054] Of course, these two outputs can also be mechanically powered via a prime mover (not shown) connected to the input shaft 202 or can be powered simultaneously by electrical and mechanical power.

[0055] Turning now to Figure 13 of the appended drawings, a CVT provided with an electric machine 400 according to a fifth illustrative embodiment will be described.

[0056] As will be obvious to those skilled in the art, the main difference between the CVT 400 and the previously described and illustrated CVTs is the fact that the CVT 400 is a single-cavity full toroidal CVT. [0057] The CVT 400 includes an input shaft 402 going through the entire CVT 400 to yield a PTO (Power-Take-Off) output 404. The shaft 402 passes through a non-rotating sleeve 406 that supports the input and output disks 408 and 410. Conventionally, drive rollers 412 are interposed between the toroidal surfaces of the disks 408 and 410.

[0058] An input connecting arrangement 414 interconnects the shaft

402 to the input disk 408. This arrangement 414 includes a cover 416 splined to the shaft 402 and to a pressure-applying mechanism 418 partially integrated with the input disk 408.

[0059] An output connecting arrangement 420 includes a gear 422 integrated with the output disk 410 and a connecting element 424 having a first end 426 meshed with the gear 422 and a second end 428 defining the variable speed output of the CVT 400.

[0060] The CVT 400 is also provided with electric machine 430 having a rotor 432 associated with the cover 416 and a stator 434 associated with the internal surface 436 of the casing 438.

[0061] Since the rotational speed of the pressure-applying mechanism varies depending on many factors such as the transmission ratio of the CVT 10 and the rotational speed of the input shaft, the electric machine is better suited to provide a rectified DC voltage, for example to recharge a battery (not shown).

[0062] The CVT provided with an electric machine as described herein can also be viewed as an electric machine having a mechanical speed control. Indeed, the electric machine is associated with the pressure-applying mechanism, itself associated with the input shaft of the CVT, allowing the electric machine to drive the input shaft of the transmission even when the input shaft is not connected to a prime mover. Of course, the CVT continues its role of controlling the speed ratio of the output shaft.

[0063] While the pressure-applying mechanism has been described herein as being associated with the input shaft of the CVT, one skilled in the art will understand that for some CVT applications, it is interesting to associate the pressure-applying mechanism with the output shaft of the CVT. When this is the case, the electric machine can still supply power to the output of the CVT.

[0064] Applications of a CVT provided with an electric machine according to the present disclosure are various.

[0065] On farm tractor primary drive, CVT driving the wheel from the engine, the electrical machine can be used as an electric motor to add momentary power to the wheel and/or to drive a mechanical implement. It can also be used as an electric generator, to charge a battery, to drive an electrical implement, to help brake the tractor. This being applicable to many different vehicles, such as construction or mining equipment.

[0066] As non-limiting examples, farm implements that are conventionally powered by the PTO (power take off) of a tractor can be provided with such a CVT to both vary the rotational speed of the implement and to recharge a battery that can either power the implement when it is not connected to the PTO or power other elements of the implement or of the tractor. Indeed, depending on the power required to operate the implement, the electric machine could also be used as an electric motor to power the implement since the rotor of the electric machine is associated with the pressure-applying mechanism, and therefore the input shaft, of the CVT. Similarly, the electric machine could be used as an electric motor to add momentary power to the implement while connected to the PTO.

[0067] The CVT provided with an electric machine described herein can also be used as an electric motor having a mechanical speed control.

[0068] When installed on a vehicle designed to go down in mines, the electric machine could be used as a generator to recharge a battery using regenerative braking. This brings another positive effect of prolonging the lifespan of the brake elements of such a vehicle that is known to be hard on brakes. Of course, the power stored in the battery can be then used to power mining equipment such as lights and tools)

[0069] It is to be understood that while applications of the CVT provided with an electric machine have been discussed hereinabove, other applications for such a combination exists.

[0070] It is also to be noted that one of ordinary skills in the art of electronics is believed to be in a position to design the electronic circuitry required for the specific application of the CVT provided with an electric machine described herein.

[0071] While the electric machine has been shown herein as being a permanent magnet electric machine, other electric machine technologies could be used.

[0072] One skilled in the art will understand that the various features of the illustrative embodiments described herein could be applied to other embodiments. As a non-limiting example, the shape and size of the electric motor of the CVT 10 illustrated in Figures 1 to 4 could be used in the CVT 400 of Figure 13.

[0073] It is to be understood that the Continually Variable

Transmission provided with an electric machine is not limited in its application to the details of construction and parts illustrated in the accompanying drawings and described hereinabove. The Continually Variable Transmission provided with an electric machine 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 Continually Variable Transmission provided with an electric machine has been described hereinabove by way of illustrative embodiments thereof, it can be modified, without departing from the spirit, scope and nature thereof.