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 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.

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;

[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 ;

[0007] Figure 4 is a sectional view taken along line 4-4 of Figure 3;

[0008] Figure 5 is a sectional view a single-cavity Continually Variable

Transmission provided with an electric machine according to a second illustrative embodiment;

[0009] Figure 6 is a sectional view a single-cavity Continually Variable

Transmission provided with an electric machine according to a third illustrative embodiment; and

[0010] Figure 7 is a sectional view a single-cavity Continually Variable

Transmission provided with an electric machine according to a second illustrative embodiment.

DETAILED DESCRIPTION

[0011] An object is generally to provide a Continually Variable

Transmission provided with an electric machine.

[0012] 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. [0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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 toroidal Continuously Variable Transmission, including amongst others, dual-cavity full toroidal CVT, half-toroidal CVT and single cavity toroidal CVT. [0018] 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.

[0019] 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.

[0020] 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.

[0021] Generally stated, a first illustrative embodiment describes a dual-cavity full toroidal CVT provided with an output drum linking a centrally provided output disk to an output shaft. The external surface of the output drum 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. Other illustrative embodiments describe single-cavity CVTs provided with at least one electric machine. [0022] Turning now more specifically to Figures 1 to 4 of the appended drawings, a dual-cavity full toroidal CVT provided with an electric machine 10 according to a first illustrative embodiment will be described.

[0023] The CVT 10 includes an input shaft 12 for receiving powerfrom 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 including an output shaft 30 transmitting the variable speed power output.

[0024] 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.

[0025] 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 an axial compression force there onto.

[0026] 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 since it is rotatably mounted about the shaft 12 via bearings 23 and a fixed sleeve 25. The driven disk 22 rotates about the same axis as the driving disks 14, 16 and the input shaft 12. [0027] 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.

[0028] 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. The drum 38 includes an external surface 42.

[0029] 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 an internal surface 46 and schematically illustrated bearings to support the input and output.

[0030] 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.

[0031] An electric machine is interposed between the external surface

42 of the drum 38 and the internal surface 46 of the casing 44. More specifically, the electric machine has a stator 48 associated with the internal surface 46 of the casing 44 and a rotor 50 associated with the external surface of the drum 38. [0032] The stator 48 includes a stack of laminations each provided with internally facing tooth 52 defining slots 54 therebetween. The slots 54 are conventionally filled with coils of wires 56.

[0033] The rotor 50 includes a ring-shaped ferromagnetic base 58 configured and sized to be mounted to the external surface 42 of the drum 38 and a plurality of permanent magnets 60 mounted to the base 58.

[0034] It is believed to be within the skills of one knowledgeable in the art to determine the number, size and spacing of the slots 54 and the number, size, shape, composition and spacing of the permanent magnets 60 to yield an electric machine having the desired features.

[0035] While the rotor has been shown as being provided with a metallic ferromagnetic base 58 to which permanent magnets are mounted, in some cases, the magnets could be directly mounted to the external surface of the drum.

[0036] Since the rotational speed of the drum 28 varies depending on many factors such as the transmission ratio of the CVT 10 and the rotational speed of the input shaft 12, the electric machine is better suited to provide a rectified DC voltage, for example to recharge a battery (not shown).

[0037] Turning now to Figure 5 of the appended drawings, a single cavity full toroidal CVT provided with an electric machine 100 will be described.

[0038] The CVT 100 includes an input shaft 102 for receiving power from a prime mover (not shown), one driving disk 104 provided with a toroidal surface 106, a driven disk 108 provided with a toroidal surface 110 facing the toroidal surface 106. The driven disk 108 is associated with an output 112 via a connecting arrangement 114.

[0039] Positioned between the driving disk 104 driven disk 108 are drive rollers 116 that are suitable for transferring rotational motion from the driving disk 104 to the driven disk 108 as discussed hereinabove.

[0040] The input shaft 102 is fixedly connected to the driving disk 104 and to a pressure-applying mechanism 118 that is positioned next to the driving disk 104 to exert an axial compression force there onto.

[0041] As the driving disk 104 rotates, it causes the rollers 116 to rotate, which in turn causes the driven disk 108 to rotate since it is rotatably mounted about the shaft 12 via bearings 120 and a fixed sleeve 122.

[0042] Again, a casing is required to protect and contain the various elements of the CVT 100. A schematically illustrated casing 124 is shown in Figure 5. 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 124 includes an internal surface 126 and schematically illustrated bearings to support the input and output.

[0043] As it will be apparent to one skilled in the art, many mechanical elements required for the adequate operation of the CVT 100 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. [0044] An electric machine is interposed between a peripheral surface

128 of the driven disk 108 and the internal surface 126 of the casing 124. More specifically, the electric machine has a stator 130 associated with the internal surface 126 of the casing 124 and a rotor 132 associated with the driven disk 108.

[0045] The stator 130 is similar to the stator 48 discussed hereinabove with respect to Figure 4.

[0046] The rotor 132 includes a ring-shaped ferromagnetic base 134 configured and sized to be mounted to the peripheral surface 128 of the driven disk 108 and a plurality of permanent magnets 136 mounted to the base 134.

[0047] Turning now to Figure 6 of the appended drawings, a single cavity full toroidal CVT provided with an electric machine 200 will be described. Since the CVT provided with an electric machine 200 is very similar to the CVT 100 illustrated in Figure 5 and described hereinabove, and for concision purpose, only the differences therebetween will be described.

[0048] Generally stated, the main difference between the CVT 200 of

Figure 6 and the CVT 100 of Figure 5 is that CVT 200 includes two electric machines 202 and 206 respectively provided between the peripheral surfaces of the driving and driven disks 204, 208 and the internal surface 210 of the casing 212.

[0049] Turning now to Figure 7 of the appended drawings, a single cavity full toroidal CVT provided with an electric machine 300 will be described. Since the CVT provided with an electric machine 300 is very similar to the CVT 100 illustrated in Figure 5 and described hereinabove, and for concision purpose, only the differences therebetween will be described.

[0050] As can readily be seen from Figure 7, the electric machine 302 is larger than the electric machine 132 since the driven disk 304 has been designed so as to present a wider peripheral surface.

[0051] Another difference is that the input shaft 306 goes through the

CVT 300 to provide a PTO output 308 coaxial with the output 310 of the CVT 300.

[0052] One skilled din the art will notice that the driving disk 312 is rotatably mounted to the non-rotating sleeve 314 via bearings 316. The pressure-applying mechanism 318 is partially integrated with the driving disk 312 and is connected to the input shaft 306 via a connecting element 320 splined both to the shaft 306 and to the mechanism 318.

[0053] Of course, many mechanical elements of the CVT 300 have been modified with respect to the CVT 100 of Figure 5.

[0054] Applications of a CVT provided with an electric machine according to the present disclosure are numerous.

[0055] On farm tractor primary traction drive, CVT driving the wheels from the engine, the electrical machine can be used as an electric motor to add momentary power to the wheels and/or to drive a mechanical implement. It can also be used as an electric generator to charge battery, to drive an electrical implement and/or to help stop the tractor. This being applicable to many different vehicles, such as construction or mining equipment. [0056] 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 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 output shaft, of the CVT. Similarly, the electric machine could be used as a motor to add momentary power to the implement while connected to the PTO.

[0057] Some embodiments of the CVT provided with an electric machine described herein can also be used as an electric motor having a mechanical speed control. For example, in the CVT 10 illustrated in Figures 1 to 4, while the input shaft has been shown herein as being associated with the pressure-applying mechanism 36 and the output shaft associated with the drum assembly 28, these roles could be reversed. Should the input shaft be associated with the drum assembly 28, the CVT provided with an electric machine 10 could be viewed as an electric machine with a CVT inserted in its rotor.

[0058] 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 for example. [0059] 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.

[0060] While the electric machines have been shown herein as being a permanent magnet electric machines, other electric machine technologies could be used. As a non-limiting example, a wound rotor could be used.

[0061] 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.

[0062] 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 CVT 10 of Figures 1 to 4 could include a second electric machine as illustrated as 202 in Figure 6.

[0063] 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.