Ball type CVT including a direct drive mode

Variable transmissions and drivelines using such transmissions having a direct drive mode, a reverse mode, and a continuously variable mode of operation using a continuously variable variator in combination with a gearbox having a one or two speed forward gear, a reverse gear, and a direct drive clutch. The direct drive clutch transfers power from the input shaft directly to the gearbox by running the variator in a unitary (1) speed ratio configuration, or by bypassing the variator altogether by using a set of clutches that disconnect the variator from the input shaft. Additional gears may be provided in the gearbox.

BACKGROUND OF THE INVENTION

A vehicle having a driveline including a continuously variable transmission allows an operator of the vehicle or a control system of the vehicle to vary a drive ratio in a stepless manner, permitting a power source of the vehicle to operate at its most efficient rotational speed.

SUMMARY OF THE INVENTION

Provided herein are variable transmissions having a direct drive mode, a reverse mode, and a continuously variable mode of operation using a continuously variable variator in combination with a gearbox having a one or two speed forward gear, a reverse gear, and a direct drive clutch that is configured to transfer power from the input shaft directly to the gearbox by running the variator in a speed ratio of one in a first configuration, or by bypassing the variator altogether by using a set of clutches that disconnect the variator from the input shaft.

Thus, provide herein is a vehicle transmission comprising an input shaft having a first direct drive clutch first member formed thereon; an output shaft; a variator comprising a first ring assembly drivingly engaged with the input shaft, a second ring assembly drivingly engaged with the output shaft, a direct drive clutch comprising the first direct drive clutch member and a second direct drive clutch member formed on the output shaft drivingly engaged with the second ring assembly; and a gearbox drivingly engaged with the second ring assembly and with the second direct drive clutch member through the output shaft, the gearbox comprising a first gear and a reverse gear; and wherein the vehicle transmission comprises a reverse mode, a direct drive mode, and a continuously variable mode.

In some embodiments, the gearbox comprises a second gear, third gear, or more than one gear, more than two gears, more than three gears, or even more gears. The gearbox, thus allows for a forward and reverse mode of operation.

In some embodiments, the gearbox is drivingly linked to a differential of a vehicle output. In some embodiments, the gearbox is drivingly linked to a differential of a vehicle output using a countershaft. In some embodiments, the countershaft comprises first countershaft gear, a reverse countershaft gear, and a pinion gear, and wherein the pinion gear is drivingly engaged with a vehicle output through the crown gear of the differential. In some embodiments, the first countershaft gear is selectively drivingly engaged with the first gear of the gearbox.

In some embodiments, the reverse countershaft gear is selectively drivingly engaged with the reverse gear of the gearbox. In some embodiments, the reverse gear comprises a reverse gear idler between the reverse gear and the reverse countershaft gear. In some embodiments, a reverse mode is enabled when a reverse clutch is engaged with the output shaft and the first gear is disengaged from the output shaft. In some embodiments, a reverse mode is enabled when a reverse clutch is engaged with the output shaft and the first gear is disengaged from the first countershaft gear.

In some embodiments, the gearbox comprises a second gear, and the countershaft comprises a second countershaft gear. In some embodiments, the second countershaft gear is selectively drivingly engaged with the second gear of the gearbox. In some embodiments, a reverse mode is enabled when a reverse clutch is engaged with the output shaft, the first gear is disengaged from the output shaft, and the second gear is disengaged from the output shaft. In some embodiments, a reverse mode is enabled when a reverse clutch is engaged with the output shaft, the first gear is disengaged from the first countershaft gear, and the second gear is disengaged from the second countershaft gear. While the gearbox described has particular elements, one of skill in the art would recognize that any number or type of gears may be used in the gearbox, so long as the resulting gearbox results in a forward and reverse mode for the transmission. Thus, the gearbox elements noted herein is for illustration, while alternative components are contemplated herein.

In some embodiments, disengaging the direct drive clutch results in continuously variable mode operation of the vehicle transmission. In some embodiments, in continuously variable mode power is transferred through the first ring assembly, one or more balls of the carrier assembly, the second ring assembly, the gearbox and to the vehicle output. In some embodiments, the gearbox increases the overall ratio spread and provides a reverse mode using the reverse gear.

In some embodiments, wherein engaging the direct drive clutch results in direct drive mode. In some embodiments, in direct drive mode power is transferred through directly from the input shaft to the gearbox. In some embodiments, in direct drive mode the variator is free to turn. In some embodiments, in direct drive mode a speed ratio of the variator is set to 1 by keeping the ball axles horizontal.

In some embodiments, the vehicle transmission further comprises a first variator clutch on the first ring assembly and a second variator clutch on the second ring assembly. In some embodiments, disengaging the first variator clutch and the second variator clutch disconnect the first ring assembly and the second ring assembly respectively from the input shaft and the output shaft. In some embodiments, a continuously variable mode exists when the first variator clutch and second variator clutch are engaged and the direct drive clutch is disengaged. In some embodiments, a direct drive mode exists when the first variator clutch and second variator clutch are disengaged and the direct drive clutch is engaged. In some embodiments, a direct drive mode exists when the variator stands still.

Provided herein is a vehicle driveline comprising an engine, a variable transmission of any of configuration described herein or obvious to one of skill in the art upon reading the disclosure herein, and a vehicle output. In some embodiments, the vehicle output comprises a wheel differential and one or more wheels of a vehicle. In some embodiments, the vehicle output comprises a wheel differential and a drive axle. In some embodiments, the dampener is disposed between the engine and the variable transmission. In some embodiments, the dampener comprises at least one torsional spring.

In some embodiments, the vehicle driveline comprises a clutch for starting the starting function. In some embodiments the dampener is coupled with a clutch for the starting function.

Provided herein is method comprising providing a variable transmission of any of configuration described herein or obvious to one of skill in the art upon reading the disclosure herein.

Provided herein is a method comprising providing a vehicle driveline of any of configuration described herein or obvious to one of skill in the art upon reading the disclosure herein.

INCORPORATION BY REFERENCE

DETAILED DESCRIPTION OF THE INVENTION

Automatic and manual transmissions are commonly used on automobile vehicles. Those transmissions become more and more complicated since the engine speed has to be adjusted to limit the consumption and the emissions of cars. This finer control of the engine speed in usual transmissions can only be done by adding gears and increasing the overall complexity and cost. 6-speed manual transmissions then become frequent as are 8 or 9 speed automatic transmissions.

Besides these transmissions are developed Continuously Variable Transmissions or CVTs. Those CVTs are of many types: belts with variable pulleys, toroidal, conical, at least. The principle of a CVT is that it enables the engine to run at its most efficient rotation speed by changing steplessly the transmission ratio in function of the speed of the car. If needed for example when accelerating, the CVT can also shift to a ratio providing more power. A CVT can change the ratio from the minimum to the maximum ratio without any interruption of the power transmission, at the opposite of usual transmissions which require an interruption of the power transmission by disengaging to shift of ratio.

As described herein, in a vehicle, a variable transmission is replaced by a conventional transmission and a clutch in a vehicle driveline. As a non-limiting example, the variable transmission that employ a ball type Continuously Variable Transmission (CVT, which is also known as CVP for continuously variable planetary, herein) and may replace a conventional transmission in a vehicle, such as a front wheel drive automobile.

Basic concepts of a ball type Continuously Variable Transmissions are described in U.S.20040616399 and AU2011224083A1, incorporated herein by reference in their entirety. Additional variable transmission details are described in U.S. application Ser. No. 13/743,951 filed Jan. 17, 2013, and/or PCT/US2013/026037 filed Feb. 14, 2013, incorporated herein by reference in their entirety. Such a CVT, adapted herein as described throughout this specification, comprises of a certain number of balls997(for example, 3-15 balls), depending on the application, two discs995,996with a conical surface contact with the balls997, as input and output, and an idler999as shown onFIG. 1. The balls are mounted on axes998, themselves hold in a cage or carrier allowing changing the ratio by tilting the ball's axes. An idler999sits below the balls in the cage. Other types of ball CVTs also exist, such as the one produced by Milner but are slightly different.

The working principle of such a CVT ofFIG. 1is shown onFIG. 2. The CVP itself works with a fraction fluid. The lubricant between the ball and the conical rings acts as a solid at high pressure, transferring the power from the input ring, through the balls, to the output ring. By tilting the ball's axis using the ball axle shaft54(shown in additional detail inFIG. 6), the ratio can be changed between input and output of the variator. When the axis is horizontal the ratio is one, when the axis is tilted the distance between the axis and the contact point change, modifying the overall ratio. When the axis is horizontal the ratio is one (1:1), when the axis is tilted the distance between the axis and the contact point change, modifying the overall ratio (input radius>output radius=underdrive; input radius<output radius=overdrive). All the balls' axes are tilted at the same time with a mechanism included in the cage.

In a car, the CVT1000is used to replace traditional transmission and is located between the engine2(such as an internal combustion engine or other type of engine) and the differential32as shown onFIG. 3. A torsional dampener (alternatively called a damper)4may be introduced between the engine and the CVT1000to avoid transferring torque peaks and vibrations that could damage the CVT. In some configurations this dampener4can be coupled with a clutch for the starting function. In some embodiments, the torsional dampener comprises a torsional spring6. In some embodiments, the vehicle driveline comprises a clutch for starting the starting function. In some embodiments the dampener is coupled with a clutch for the starting function.

The variable transmission is located between an engine2and a vehicle output34. The vehicle output34may include a differential32and a drive axle or a differential crown gear (for example, as shown inFIGS. 4 and 5), however, it is understood that other vehicle outputs may be used. The vehicle output may comprise bearings36a,36b,36c,36dand wheels38a,38bof the vehicle. A torsional dampener4may also be included, the torsional dampener4disposed between the engine2and the variable transmission1000to reduce vibration and torque peaks. A clutch (not shown) can be added to provide the starting function.

FIG. 4depicts an embodiment of the transmission composed of a dampener4between the ICE2and the variable transmission1000. The variable transmission ofFIG. 4also includes the variator100, a clutch102, and a two-speed gearbox104. The gearbox104for may include a reverse mode, in addition to the two-speed functionality. This gearbox104may be an automatic gearbox known in the art for automotive or other applications.

The variator100ofFIG. 4is also depicted inFIG. 6.FIG. 5is a variation ofFIG. 4, and thus the description ofFIG. 6also applies toFIG. 5, except for the addition of first variator clutch42on first assembly8, and the addition of second variator clutch44and second assembly10inFIG. 5. Thus,FIG. 6depicts the variator100comprising a first ring assembly8, a second ring assembly10, and a carrier assembly disposed therebetween. The carrier assembly includes a plurality of variator balls62a,62bhaving tiltable axle shafts54a,54bas described herein. In some embodiments, the first ring assembly8is rotatably disposed in a housing; the first ring assembly8comprises a first variator ball engagement surface50that is in driving engagement with a plurality of variator balls62a,62bof the carrier assembly. The first ring assembly8may be drivingly engaged with input shaft40.

As shown inFIG. 6, first variator ball engagement surface50is formed in a distal end of the first ring assembly8. In some embodiments, the first variator ball engagement surface50is a conical surface or a concave or convex toroidal surface in contact with or slightly spaced apart from each of the variator balls62a,62b. In some embodiments, the first variator ball engagement surface50is in driving engagement with each of the variator balls62a,62bof the carrier assembly through one of a boundary layer type friction and an elastohydrodynamic film.

The carrier assembly ofFIG. 6is rotatably disposed in the housing and is drivingly engaged with the first ring assembly. The carrier assembly comprises an annular arrangement of the plurality of tiltable variator balls62a,62beach having tiltable ball axle shafts54a,54b. A cage of the carrier assembly may be configured to be prevented from rotating relative to the housing by a grounding device linked to said ground52. In some embodiments, each of the ball axle shafts54a,54bis adjusted using a cam style tilting mechanism. In some embodiments, each of the ball axle shafts54a,54bis adjusted using a split carrier axle skewing mechanism (not shown).

As depicted inFIG. 6, at least, the second ring assembly10is rotatably disposed in the housing. The second ring assembly10comprises and a second variator ball engagement surface58that is in driving engagement with variator balls62a,62bof the carrier assembly. In some embodiments, the second variator ball engagement surface58is formed in a distal end of the second ring assembly. In some embodiments, the second variator ball engagement surface58is a conical surface or a concave or convex toroidal surface in contact with or slightly spaced apart from each of the variator balls62a,62b. In some embodiments, the second variator ball engagement surface58is in driving engagement with each of the variator balls62a,62bof the carrier assembly through one of a boundary layer type friction and an elastohydrodynamic film.

Provided herein are variable transmissions having a direct drive mode, a reverse mode, and a continuously variable mode of operation using a continuously variable variator in combination with a gearbox having a one or two speed forward gear, a reverse gear, and a direct drive clutch that is configured to transfer power from the input shaft directly to the gearbox by running the variator in a speed ratio of one, or by bypassing the variator altogether by using a set of clutches that disconnect the variator from the input shaft.

Thus, provide herein is a vehicle transmission comprising an input shaft having a first direct drive shaft first member formed thereon; an output shaft; a variator comprising a first ring assembly drivingly engaged with the input shaft, a second ring assembly drivingly engages with the output shaft, and a carrier assembly, a direct drive clutch comprising the first direct drive clutch member and a second direct drive clutch member formed on the output shaft drivingly engaged with the second ring assembly; and a gearbox drivingly engaged with the second ring assembly and with the second direct drive clutch member through the output shaft, the gearbox comprising a first gear and a reverse gear; and wherein the vehicle transmission comprises a reverse mode, a direct drive mode, and a continuously variable mode.

In some embodiments, the gearbox comprises a second gear.

In some embodiments, the gearbox is drivingly linked to a differential of a vehicle output. In some embodiments, the gearbox is drivingly linked to a differential of a vehicle output using a countershaft. In some embodiments, the countershaft comprises first countershaft gear, a reverse countershaft gear, and a pinion gear, and wherein the pinion gear is drivingly engaged with a vehicle output through the crown wheel of the differential. In some embodiments, the first countershaft gear is selectively drivingly engaged with the first gear of the gearbox.

In some embodiments, the reverse countershaft gear is selectively drivingly engaged with the reverse gear of the gearbox. In some embodiments, the reverse gear comprises a reverse gear idler between the reverse gear and the reverse countershaft gear. In some embodiments, a reverse mode is enabled when a reverse clutch is engaged with the output shaft and the first gear is disengaged from the output shaft. In some embodiments, a reverse mode is enabled when a reverse clutch is engaged with the output shaft and the first gear is disengaged from the first countershaft gear.

In some embodiments, the gearbox comprises a second gear, and the countershaft comprises a second countershaft gear. In some embodiments, the second countershaft gear is selectively drivingly engaged with the second gear of the gearbox. In some embodiments, a reverse mode is enabled when a reverse clutch is engaged with the output shaft, the first gear is disengaged from the output shaft, and the second gear is disengaged from the output shaft. In some embodiments, a reverse mode is enabled when a reverse clutch is engaged with the output shaft, the first gear is disengaged from the first countershaft gear, and the second gear is disengaged from the second countershaft gear.

In some embodiments, disengaging the direct drive clutch results in continuously variable mode operation of the vehicle transmission. In some embodiments, in continuously variable mode power is transferred through the first ring assembly, one or more balls of the carrier assembly, the second ring assembly, the gearbox and to the vehicle output. In some embodiments, the gearbox increases the overall ratio spread and provides a reverse mode using the reverse gear.

In some embodiments, wherein engaging the direct drive clutch results in direct drive mode. In some embodiments, in direct drive mode power is transferred through directly from the input shaft to the gearbox. In some embodiments, in direct drive mode the variator is free to turn. In some embodiments, in direct drive mode a speed ratio of the variator is set to 1 by keeping the ball axles horizontal.

In some embodiments, the vehicle transmission further comprises a first variator clutch on the first ring assembly and a second variator clutch on the second ring assembly. In some embodiments, disengaging the first variator clutch and the second variator clutch disconnect the first ring assembly and the second ring assembly respectively from the input shaft and the output shaft. In some embodiments, a continuously variable mode exists when the first variator clutch and second variator clutch are engaged and the direct drive clutch is disengaged. In some embodiments, a direct drive mode exists when the first variator clutch and second variator clutch are disengaged and the direct drive clutch is engaged. In some embodiments, a direct drive mode exists when the variator stands still.

Provided herein is a vehicle driveline comprising an engine, a variable transmission of any of configuration described herein or obvious to one of skill in the art upon reading the disclosure herein, and a vehicle output. In some embodiments, the vehicle output comprises a wheel differential and one or more wheels of a vehicle. In some embodiments, the vehicle output comprises a wheel differential and a drive axle. In some embodiments, the dampener is disposed between the engine and the variable transmission. In some embodiments, the dampener comprises at least one torsional spring. In some embodiments, the vehicle driveline comprises a clutch for starting the starting function. In some embodiments the dampener is coupled with a clutch for the starting function.

Provided herein is a method comprising providing a variable transmission of any of configuration described herein or obvious to one of skill in the art upon reading the disclosure herein.

Provided herein is a method comprising providing a vehicle driveline of any of configuration described herein or obvious to one of skill in the art upon reading the disclosure herein.

InFIG. 4, the engine2is connected to the first ring assembly8of the variator100through the dampener4and the input shaft40. The input shaft40also links to the direct drive clutch102comprising a first direct drive clutch member12and a second direct drive clutch member14. The first direct drive clutch member12may be formed at an end of the input shaft40. A second ring assembly10of the variator100is drivingly engaged with the second direct drive clutch member14of the direct drive clutch102and is drivingly engaged with to the gearbox104. The gearbox104is drivingly linked to the differential32and the vehicle output34of the vehicle using a countershaft28. The countershaft28has fixed upon it a first countershaft gear106, second countershaft gear108, a reverse countershaft gear110, and a pinion gear112. It is anticipated that the first countershaft gear106, second countershaft gear108, a reverse countershaft gear110, and a pinion gear112are of varying diameters, as shown inFIG. 4, or5, for example, or may be in any combination of diameters, that are the same or different, depending on the needs of the CVP.

The first countershaft gear106is drivingly engaged with a first gear20. The second countershaft gear108is drivingly engaged with a second gear22. The reverse countershaft gear110is drivingly engaged with a reverse gear24through a reverse gear idler26. A reverse mode may be enabled when a reverse clutch16is engaged with the output shaft18and the first gear20and the second gear22are disengaged from the output shaft18. Alternatively, a reverse mode may enabled when a reverse clutch16is engaged with the output shaft18and the first gear20is disengaged from the first countershaft gear106, and the second gear22is disengaged from the second countershaft gear108. The crown ring112is drivingly engaged with the differential32through a differential crown wheel30.

The central part of the variable transmission in the embodiment ofFIG. 4includes a variator100. A ball ramp on each side of the variator provides the clamping force necessary to transfer the torque. Ball ramps48, indicated inFIGS. 4, 5, and 6by a circle between a pair of vertical lines, making up a first thrust ring on the first ring assembly and a second thrust ring on the second ring assembly are disposed between components of the variable transmission as shown to generate an amount of axial force necessary for proper operation of the variable transmission (i.e. transfer of torque); however, it is understood that the amount of axial force necessary for proper operation may be generated by a clamping mechanism (not shown) or as a load applied during assembling of the variable transmission. Thus, as depicted inFIG. 4, a ball ramp on each side of the variator100provides the clamping force necessary to transfer the torque in this embodiment.

This configuration can be used in two different modes: continuously variable mode and direct drive (DD). In continuously variable mode, the direct drive clutch102is not engaged and the power is transferred through the first ring assembly8, the variator100, the second ring assembly10, the gearbox104and finally goes to the vehicle output34. The gearbox104is added to increase the overall ratio spread and to provide a reverse mode using the reverse gear of24and reverse gear idler26drivingly engaged with reverse countershaft gear110on countershaft28. As previously noted, countershaft28is drivingly engaged with differential crown wheel30which drives the vehicle output34.

The direct drive mode is applied by engaging the direct drive clutch102. By doing this, the power will directly go the gearbox104. In this mode, the variator100is free to turn, and its speed ratio must be set to 1 (wherein the first ring assembly8and the second ring assembly10turn together) by keeping the ball axles horizontal.

To avoid having power losses in the transmission when in the direct drive mode, two clutches (labeled as first variator clutch42and second variator clutch44inFIG. 5) may be added to disconnect the first ring assembly8and the second ring assembly10from the input shaft40and output shaft18.FIG. 5shows this variant of the concept.

In the embodiment ofFIG. 5, a continuously variable mode exists when the first variator clutch42and second variator clutch44are engaged and the direct drive clutch102is disengaged. In direct drive mode, using the embodiment ofFIG. 5, the first variator clutch42and second variator clutch44are disengaged, thus, the variator100stands still and avoids losses due to the friction in the variator100.

Embodiments of the variable transmission described herein or that would be obvious to one of skill in the art upon reading the disclosure herein are contemplated for use in a variety of vehicle drivelines. For non-limiting example, the variable transmissions disclosed herein may be used in bicycles, mopeds, scooters, motorcycles, automobiles, electric automobiles, trucks, sport utility vehicles (SUV's), lawn mowers, tractors, harvesters, agricultural machinery, all terrain vehicles (ATV's), jet ski's, personal watercraft vehicles, airplanes, trains, helicopters, buses, forklifts, golf carts, motorships, steam powered ships, submarines, space craft, or other vehicles that employ a transmission.

While the figures and description herein are directed to ball-type variators (CVTs), alternate embodiments are contemplated another version of a variator (CVT), such as a Variable-diameter pulley (VDP) or Reeves drive, a toroidal or roller-based CVT (Extroid CVT), a Magnetic CVT or mCVT, Ratcheting CVT, Hydrostatic CVTs, Naudic Incremental CVT (iCVT), Cone CVTs, Radial roller CVT, Planetary CVT, or any other version CVT.