WO2018083458A1

WO2018083458A1 - Transmissions

Info

Publication number: WO2018083458A1
Application number: PCT/GB2017/053279
Authority: WO
Inventors: David Mcmanamon
Original assignee: Transfiniti Limited
Priority date: 2016-11-01
Filing date: 2017-11-01
Publication date: 2018-05-11
Also published as: GB201618418D0

Abstract

A transmission (10) comprising a disc variator (16) and an epicyclic gear set (40) in which the input shaft (18) of the variator (16) is connected to a first input (42) of the epicyclic gear set (40), and in which, an output (38) of the variator (16) is connected to a second input (46) of the epicyclic gear set (40). By changing the contact point (19) of a roller (34) of the variator (16), the relative speeds of the inputs (42, 46) of the epicyclic gear set (40) can be varied to provide infinitely variable control of the speed and/or direction of an output (50) of the epicyclic gear set (40). The transmission (10) can be incorporated into a transaxle transmission (20), which has a variator (16) and two epicyclic gear sets (40, 41), the respective outputs (50, 51) of which can be used to independently control the speeds and/or directions of, for example, (60, 62) connected to the respective epicyclic gear sets' output shafts (50, 51).

Description

Title: Transm

Description: This invention relates to transmissions, for example, transmissions suitable for use in motor vehicles and the like. Infinitely Variable Transmissions ("IVTs") are well-known, and often comprise an epicyclic gear set. An epicyclic gear set has the beneficial property of having two inputs and an output. By varying the relative speeds and/or directions of the inputs, the speed and/or direction of the output can be adjusted.

To obtain the requisite relative speed variation of the inputs, a variator is often used. A variator typically has a driving disc and a driven disc, and the relative speeds of the driving and driven discs can be adjusted, for example, by using rollers, whose contact points with the driving and driven discs are adjustable. By adjusting the position of the rollers' contact points, this results in the driving and driven discs rotating at different speeds and/or in different directions. Therefore, by connecting the discs separately to the two inputs of the epicyclic gear set, the output speed and/or direction of the epicyclic gear set can be selected at will.

This invention aims to provide an improved and/or alternative transmission and/or an improved and/or alternative IVT.

According to one aspect of the invention, there is provided a transmission comprising an input shaft connected to the input of a disc variator and one input of an epicyclic gear set, wherein an output of the disc variator is connected to another input of the epicyclic gear set, the disc variator comprising: a driving disc affixed to the input shaft and a driven disc driven at the same speed, but in an opposite direction to, the driving disc; a roller mounted between, and thus driven for rotation by, the driving and driven discs, the roller driving the output of the disc variator; and being axially moveable relative to the driving and driven discs so as to contact the driving and driven discs at a selected radial position, the speed of the primary output shaft thus being determined by the said selected radial position. According to another aspect of the invention, there is provided a transmission comprising an input system and an output system: the input system comprising a disc variator comprising: in input shaft connected to a power source; a driving disc affixed to the input shaft; a driven disc mounted for rotation about the input shaft; and means for driving the driven disc at the same speed, but in an opposite direction to, the driving disc - the output system comprising: a roller mounted between, and thus driven for rotation by, the driving and driven discs; the roller driving an axle forming a primary output shaft; and the roller being axially moveable relative to the driving and driven discs so as to contact the driving and driven discs at a selected radial position, the speed of the primary output shaft thus being determined by the said selected radial position; and an epicyclic gear set comprising: a first input connected to the input shaft; a second input connected to the primary output shaft; and an output, the speed of the output being a function of the speeds of the first and second inputs.

The transmission suitably comprises two output systems, each output system comprising: a roller, the roller being mounted between, and thus driven for rotation by, the driving and driven discs; the roller driving an axle forming a primary output shaft; and being axially moveable relative to the driving and driven discs so as to contact the driving and driven discs at a selected radial position, the speed of the primary output shaft thus being determined by the said selected radial position; and an epicyclic gear set comprising: a first input connected to the input shaft; a second input connected to the primary output shaft; and an output, the speed of the output being a function of the speeds of the first and second inputs.

Suitably, the first inputs of the two or more epicyclic gear sets are connected to the input shaft and rotate at the same speed.

Suitably, where two output systems are provided, the second input of one of the output systems is connected to the primary output shaft via a reversing mechanism, such as an idler gear.

Embodiments of the invention shall now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of a transmission in accordance with an embodiment of the invention;

Figure 2 is substantially the same as Figure 1, but with the roller set at a different radial position;

a schematic diagram of a transmission in accordance with an embodiment of the invention;

Figure 3 is a schematic diagram of a transaxle transmission in accordance with another embodiment of the invention;

Figures 4 and 5 are partial perspective views of an embodiment of a transmission as shown in Figure 3; and

Figure 6 is partial perspective view of a 5-disc variant of a transmission in accordance with the invention.

Referring to Figures 1 & 2 of the drawings, a first embodiment of a transmission 10 in accordance with the invention comprises an input system 12 and an output system 14. The input system 12 comprises a disc variator 16, which is driven for rotation, for example, by an internal combustion engine or an electric motor (not shown) via an input shaft 18. The variator 16 has a driving disc 20 that is affixed to the input shaft 18 and a driven disc 22 that is mounted for rotation about the input shaft 18.

Means 24 for driving the driven disc 22 at the same speed, but in an opposite direction to, the driving disc 20 is also provided.

In the embodiment shown in Figure 1, the means 24 for driving the driven disc at the same speed, but in an opposite direction to, the driving disc comprises a layshaft 26 having gears 28 at either end that engage with the outer diameters of the driving disc 20 and the driven disc 22.

In the embodiment shown in Figure 2, the means 24 for driving the driven disc 22 at the same speed, but in an opposite direction to, the driving disc 20 comprises a bevel gear 30 that engages with corresponding bevel gear portions 29 formed on the outer diameters of the driving disc 20 and the driven disc 22. In other embodiments, the means 24 for driving the driven disc 22 at the same speed, but in an opposite direction to, the driving disc 20 comprises a set of idler rollers 32 that are interposed between the driving disc 20 and the driven disc 22.

The output system 14 comprises a roller 34 that is mounted between, and thus driven for rotation by, the driving 20 and driven discs 22. Traction fluid (not shown) is used to enable the roller 34 to be efficiently driven by the driving 20 and driven discs 22, and the roller 34 is clamped between the driving 20 and driven discs 22 by the application of an axial force 36 to the variator discs 20, 22.

The roller 34 is connected to, and drives, an axle 38 that forms a primary output shaft.

As can be seen by comparing Figures 1 and 2, the roller 34 is axially moveable relative to the driving 20 and driven 22 discs' radii, so that is can be arranged to contact the driving 20 and driven 22 discs at a selected radial position 19. The speed of the primary output shaft 38 is thus determined by the said selected radial position 19.

The transmission 10 further comprises an epicyclic gear set 40, which has a first input (the sun gear, in this example) 42 connected to the input shaft 18 via a set of bevel gears 44.

The epicyclic gear set 40 also has a second input (the ring gear, in this example) 46 connected to the primary output shaft 38 via a gear 48.

Because the speed of the primary output shaft 38 is determined by the radial position 19 of the roller 34 relative to the radii of the driving 20 and driven 22 discs, so the speed of the second input 46 of the epicyclic gear set 40 can be varied. This results in the output speed of an output shaft 50 of the epicyclic gear set 40 (in this example, connected to the planet gear carrier 52) being a function of the two input speeds 42, 46, as will be readily understood by the person skilled in the art. Therefore, the speed and/or direction 54 of the output shaft 50 can be varied by adjusting the radial position 19 of the roller 34 relative to the radii of the driving 20 and driven 22 discs.

Figure 3 of the drawings shows a transaxle transmission 20 in accordance with the invention. Here, it can be seen that there are two driving discs 20 and one driven disc 22, and two sets of rollers 34, 35. The two sets of rollers 34, 35 are independently axially moveable relative to the driving 20 and driven 22 discs' radii, so that is each set can be arranged to contact the driving 20 and driven 22 discs at a selected (the same or different) radial positions 19, 19'. The speed of the primary output shafts 38, 39 are thus determined by the respective selected radial positions 19, 19'.

Each set of rollers 34, 35 is connected to its own epicyclic gear set 40, 41, and each epicyclic gear sets 40, 41 output shaft 50, 51 is connected to, in the illustrated example, a wheel 60, 62 of a vehicle. The second epicyclic gear set 41 can be the same as the first 40, but in the illustrated example, it also comprises a reversing gear 43. It will be appreciated that the transaxle transmission 20 can be used to provide not only IVT gearing, but also a differential by setting the contact points of the rollers 34, 35 at different radial positions relative to the driving 20 and driven discs 22.

An embodiment of the transaxle transmission 20 of Figure 3 is shown in perspective view in Figures 4 and 5 of the drawings, and identical reference signs have been used to identify identical features respectively.

Figure 6 of the drawings is a perspective view of another, 5-disc version, of the transaxle transmission 20 of Figures 3 to 5. Here, it can be seen that the axles 38 forming the primary output shafts are spline shafts, and that the rollers 34, 35 are mounted so that they can move axially along their respective spline shafts 38. Movement of the rollers 34, 35 relative to their respective spline shafts 38 is accomplished by a carriage 66 for each set of rollers 34, 35, which pushes them in either direction along their respective spline shaft 38. The carriages 66 are displaced by a roller 68 that engages an angled slot 70 formed in a respective carriage shifter 72. Each carriage shifter 72 is independently moved by an actuator 74, 76, such as a linear servo motor, a hydraulic ram, mechanical linkage or the like.

The input shaft 18 is typically connected to an internal combustion engine of an electric motor. A mechanism may be interposed between the internal combustion engine/electric motor and the input shaft 18, which as the applied torque increases, so the axial force 36 applied to the variator discs 20, 22 is increased. This can be accomplished by a threaded connection or by way of a cam mechanism 80, which applies an increasing axial force to one of the discs 22, 22 as the torque applied to the input shaft 18 increases. This configuration reduces wear and losses when the transmission is not fully- loaded, whilst enabling the torque density to be increased as the applied torque increases.

In summary, the invention can be described as being a transmission (10) comprising a disc variator (16) and an epicyclic gear set (40) in which the input shaft (18) of the variator (16) is connected to a first input (42) of the epicyclic gear set (40), and in which, an output (38) of the variator (16) is connected to a second input (46) of the epicyclic gear set (40). By changing the contact point (19) of a roller (34) of the variator (16), the relative speeds of the inputs (42, 46) of the epicyclic gear set (40) can be varied to provide infinitely variable control of the speed and/or direction of an output (50) of the epicyclic gear set (40). The transmission (10) can be incorporated into a transaxle transmission (20), which has a variator (16) and two epicyclic gear sets (40, 41), the respective outputs (50, 51) of which can be used to independently control the speeds and/or directions of, for example, (60, 62) connected to the respective epicyclic gear sets' output shafts (50, 51).

Advantages of the invention are manifold and include, but are not limited to:

• Increased torque density compared with known IVTs because there are more roller 34-disc 20, 22 contact points, thus increasing the frictional torque transmission capability of the transmission 10, 20, as well as providing some redundancy in the event of one of the rollers ceasing to contact its respective disc 20, 22;

• Increased torque density compared with known IVTs because some of the torque is transmitted directly to an input of the or each epicyclic gear set 40, 41, via the input shaft;

• Combining the functions of a gearbox (e.g. an IVT gearbox) and a differential into a single unit;

• Weight savings;

• Reduced size;

• Fewer moving parts compared with a conventional IVT and differential setup; and

• Fewer bearings.

Claims

Claims:

1. A transmission (10) comprising an input shaft (18) connected to the input (20) of a disc variator (16) and one input (42) of an epicyclic gear set (40), wherein an output (38) of the disc variator is connected to another input (48) of the epicyclic gear set (40), the disc variator (16) comprising: a driving disc (20) affixed to the input shaft (18) and a driven disc (22) driven at the same speed, but in an opposite direction to, the driving disc (20); a roller (34) mounted between, and thus driven for rotation by, the driving (20) and driven (22) discs, the roller (34) driving the output (38) of the disc variator (16); and being axially moveable relative to the driving (20) and driven discs (22) so as to contact the driving (20) and driven (22) discs at a selected radial position (19), the speed of the primary output shaft (38) thus being determined by the said selected radial position (19).

2. The transmission (10) of claim 1, comprising an input system (12) and an output system (14): the input system (12) comprising the disc variator (16), whose input shaft (18) is connected to a power source; and means (26, 28, 30) for driving the driven disc (22) at the same speed, but in the opposite direction to, the driving disc (20); and the output system comprising the epicyclic gear set (40) whose first input (42) is connected to the input shaft (18); whose second input (48) connected to the primary output shaft (38); and whose output (50, 52) is determined by the speeds of the first (42) and second (38) inputs.

3. The transmission (10) of claim 2, comprising two or more output systems (14), each output system (14) comprising: a roller (34, 35) which is mounted between, and thus driven for rotation by, the driving (20) and driven (22) discs of the variator (16), each roller (34, 35) driving a respective axle (38, 39) forming a respective primary output shaft, and each roller (35, 35) being axially moveable relative to the driving (20) and driven (22) discs so as to contact the driving (20) and driven (22) discs at a selected radial positions (19, 19'), the speed of the primary output shafts (38, 39) thus being determined by the said selected radial positions (19, 19'), each epicyclic gear set (40, 41) comprising: a first input (42) connected to the input shaft (18); a second input (48) connected to their respective primary output shaft (38, 39); and a respective output (50, 51), the speeds of the outputs (50, 51) each being independent functions of the speeds of the first (41) and the respective (38, 39) second inputs.

4. The transmission of claim 3, wherein the first inputs (42) of the two or more epicyclic gear sets (40, 41) are connected to the input shaft (18) and rotate at the same speed.

5. The transmission (10) of claim 3 or claim 4, wherein the second input of one of the output systems is connected to the primary output shaft via a reversing mechanism.

6. The transmission (10) of any preceding claim, wherein the means (24) for driving the driven disc (22) at the same speed, but in an opposite direction to, the driving disc (20) comprises any one or more of the group comprising: a layshaft (26) having gears (28) at either end that engage with outer diameters of the driving disc (20) and the driven disc (22); a bevel gear (30) that engages with corresponding bevel gear portions (29) formed on outer diameters of the driving disc (20) and the driven disc (22); and a set of idler rollers (32) that are interposed between the driving disc (20) and the driven disc (22).

7. The transmission (10) of any preceding claim, wherein the roller or rollers (34) are clamped between the driving (20) and driven discs (22) by the application of an axial force (36) to the variator discs (20, 22).

8. The transmission (10) of any preceding claim, further comprising traction fluid at the contact point or points between the or each roller (34) and the driving (20) and driven discs (22).

9. The transmission (10) of any preceding claim, wherein the first input of the epicyclic gear set (40) is to a sun gear (42), thereof; wherein the second input (38) of the epicyclic gear set (40) is to a ring gear (46), and wherein the output (50) of the epicyclic gear set (40) it to a planet carrier (52) thereof.

10. The transmission (10) of claim 9, wherein the second input (38) is connected to the ring gear (46) via one or more further gears (48).

11. A transaxle transmission (20) comprising a transmission according to any of claims 3 to 12, in which there are two output systems (14).

12. The transaxle transmission (20) of claim 11, wherein the rollers (34, 35) are mounted on spline shafts (38) and wherein displacement of the rollers (34, 35) relative to the variator discs (20, 22) is by bay of a respective carriage (66) for each set of rollers (34, 35), which pushes them in either direction along their respective spline shafts (38).

13. The transaxle transmission (20) of claim 12, wherein the carriages (66) are displaced by a roller (68) that engages an angled slot (70) formed in a respective carriage shifter (72), each carriage shifter (72) being independently moved by an actuator (74, 76).

14. The transaxle transmission (20) of claim 11, 12 or 17, wherein the input shaft (18) is connected to an internal combustion engine of an electric motor., and wherein a mechanism is interposed between the internal combustion engine/electric motor and the input shaft (18), which as the applied torque increases, increases an axial force (36), which is applied to the variator discs (20, 22).

15. The transaxle transmission (20) of claim 14, wherein the mechanism comprises a threaded connection or a cam mechanism (80), which applies an increasing axial force (36) to one of the discs (22, 22) as the torque applied to the input shaft (18) increases.