Continuously variable multimode transmission

Abstract

Continuously variable transmission, comprehensive: a first planetary gear set (38) which is a first gear component and a second transmission component; a double planetary gear unit (40) comprising an input component, an output component, a third gear component and a fourth gear component; a clutch (50); and a first brake (70); wherein the first transmission component receives a first mechanical input power for the first planetary gear (38) from a motor (14a); wherein the third transmission component receives a second mechanical input power for the double planetary gear (40) from a continuously variable energy source (18); wherein the second gear component directly transfers energy to the input component of the double planetary gear unit (40); wherein the clutch (50) is designed to engage with the first transmission component and the second transmission component in order to control the power transmission between the first transmission component and the second transmission component; wherein the first brake (70) is designed to engage with the fourth transmission component in order to stop the rotation of the fourth transmission component; wherein the output component is designed to receive mechanical power directly from the input component and the fourth gear component; wherein the double planetary gear (40) is designed to sum mechanical power from the motor (14) and the continuously variable energy source (18) and to supply the summed power to the output component, characterized in that during operation of the motor (14) a controlled actuation of one or more of the first brake (70) and the clutch (50) causes the output component to be supplied with power from the continuously variable energy source (18), but not from the motor (14).

Description

[0001] This disclosure relates to a continuously variable transmission having the features of the preamble of patent claim 1.

[0002] Such a generic continuously variable transmission is known, for example, from WO 2008 / 008 615 A2.

[0003] In a wide variety of environments, it may be useful to use both a conventional engine (e.g., an internal combustion engine) and a continuously variable energy source (e.g., an electric or hydraulic motor, a variable chain drive, etc.) to provide useful power. For example, a portion of the engine power may be diverted to drive a first continuously variable machine (e.g., a first electric machine acting as a generator), which in turn may drive a second continuously variable machine (e.g., a second electric machine acting as a motor using electrical power from the first electric machine). In certain designs, energy from both types of sources (e.g., a motor and a continuously variable energy source) may be used for the final power output (e.g.,to a motor axle) via an infinitely variable transmission ("IVT") or a finite ratio continuously variable transmission ("CVT"). This may be referred to as "split-mode" or "split-path" operation because power transfer can be split between the mechanical path from the engine and the continuously variable path. Split-mode operation can be achieved in several known ways. For example, a planetary gear train may be used to sum rotary power from a motor and from an electric machine, with the summed power being transferred downstream within an associated driveline. This can enable the delivery of power (e.g., to vehicle wheels) with an effectively infinite, continuously variable transmission ratio.However, several problems may arise, including limitations on the maximum achievable speed of adjustable energy sources.

[0004] A continuously variable transmission is disclosed. According to one aspect of the disclosure, a continuously variable transmission includes a first planetary gear set including a first gear component and a second gear component; and a double planetary gear set including an input component, an output component, a third gear component, and a fourth gear component. The continuously variable transmission also includes a clutch and a brake. The first gear component receives a first mechanical input for the first planetary gear set from an engine. The third gear component receives a second mechanical input for the double planetary gear set from a continuously variable power source. The second gear component directly transfers power to the input component of the double planetary gear set.The clutch is configured to engage the first transmission component and the second transmission component to control the transfer of power between the first transmission component and the second transmission component. The brake is configured to engage the fourth transmission component to stop rotation of the fourth transmission component. The output component is configured to receive mechanical power directly from the input component and the fourth transmission component. The double planetary gear set is configured to sum mechanical power from the motor and the continuously variable power source and deliver the summed power to the output component. During operation of the motor, controlled application of one or more of the first brake and the clutch causes the output component to be powered by the continuously variable power source, but not by the motor.

[0005] One or more of the following features may also be included in the disclosed transmission. The first transmission component may include a first planetary gear carrier supporting one or more first planetary gears. The second transmission component may include a first sun gear. The input component may include a first ring gear. The third transmission component may include a second sun gear. The fourth transmission component may include a second ring gear. The output component of the dual planetary transmission may include a second planetary gear carrier supporting one or more second planetary gears, wherein the one or more second planetary gears mesh with one or more of the input component and the fourth transmission component. The output component may transmit mechanical power to a gearshift including one or more gear ratios.The continuously variable power source may comprise one or more of a pair of electric machines and a hydraulic machine.

[0006] According to another aspect of the disclosure, a continuously variable transmission includes a first planetary gear set including a first input component, a first output component, and a first transmission component. The continuously variable transmission includes a double planetary gear set including a second input component, a second transmission component, a third transmission component, and a second output component. The continuously variable transmission also includes a first clutch, a second clutch, and a brake. The first input component receives a first mechanical input power to the first planetary gear set from an engine. The second input component receives mechanical power directly from the first output component.One or more of the first clutch, the second clutch, and the brake is or are configured to engage with one or more of the first input component, the first output component, and the first transmission component to control the mechanical power transfer between the engine and the double planetary gear train. One or more of the second and third transmission components receives or receive a second mechanical input power for the double planetary gear train from a continuously variable power source. The double planetary gear train is configured to sum mechanical power from the engine and the continuously variable power source and supply the summed power to the second output component.During operation of the engine, controlled actuation of one or more of the first clutch, the second clutch, and the brake causes the second output component to be energized by the continuously variable energy source but not by the engine.

[0007] The first input component may include a first sun gear, wherein the first clutch is configured to engage the first sun gear to control a transfer of mechanical power between the first sun gear and the motor. The first transmission component may include a first ring gear, wherein the brake is configured to engage the first ring gear to stop rotation of the first ring gear. The first output component may include a first planetary carrier, wherein the second clutch is configured to engage the first planetary carrier and the first ring gear to control the transfer of mechanical power between the first planetary carrier and the first ring gear.The second output component may include a second planetary gear carrier, wherein the second planetary gear carrier is configured to receive mechanical power directly from both the second gear component and a fourth gear component included in the double planetary gear set. The second gear component may include a second sun gear. The fourth gear component may include a second ring gear. The second input component may transmit mechanical power directly to a third ring gear included in the double planetary gear set. The third gear component may include a third sun gear. A third planetary gear carrier carrying one or more planetary gears may be included in the double planetary gear set, wherein the one or more planetary gears mesh with the third ring gear and the third sun gear.

[0008] The continuously variable transmission may further include a third clutch configured to engage the second output component and a fourth clutch configured to engage the second output component. Controlled actuation of the third and fourth clutches may control a flow path of mechanical power through the double planetary gear set to the second output component. The third clutch may be configured to engage a third planetary gear carrier for transferring mechanical power between the third planetary gear carrier and the second output component. The second control clutch may be configured to controllably engage a second ring gear included in the double planetary gear set for transferring mechanical power between the second ring gear and the second output component.

[0009] According to another aspect of the disclosure, a continuously variable transmission includes a double planetary gear train including a first input component, a second input component, and an output component. The continuously variable transmission includes a clutch, a first brake, and a second brake. The first input component is configured to receive a first mechanical input to the double planetary gear train from an engine. The clutch is configured to engage the first input component to control a transfer of mechanical power between the first input component and an engine. The second input component receives a second mechanical input to the double planetary gear train from a continuously variable power source. The double planetary gear train is configured to sum mechanical power from the engine and the continuously variable power source and deliver the summed power to the output component.During operation of the motor, controlled actuation of one or more of the clutch, the first brake, and the second brake causes the output component to be driven by the infinitely variable energy source, but not by the motor.

[0010] The double planetary gear set may include a first sun gear, a second sun gear, a first ring gear, a second ring gear, a first planet carrier supporting one or more first planet gears, and a second planet carrier supporting one or more second planet gears. The first input component may include the first sun gear. The second input component may include the second sun gear. The output component may include the second planet carrier. The one or more second planet gears mesh with the second sun gear and the first ring gear. The first ring gear may be integrally formed with the first planet carrier. The one or more second planet gears mesh with the first sun gear and the second ring gear.The first brake may be configured to engage one or more of the second ring gear and the first planetary gear carrier to control relative movement of the second ring gear and the first planetary gear carrier. The second brake may be configured to engage the second ring gear to stop rotation of the second ring gear.

[0011] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description, drawings, and claims. Fig. 1 is a side view of an example of a vehicle that may include a continuously variable transmission; Fig. 2 is a schematic view of a powertrain of the vehicle of Fig. 1; Fig. 3 is a schematic view of a continuously variable transmission used in the powertrain of Fig. 2 may be included; Fig. Figure 4 is a graphical representation of continuously variable power source speeds and vehicle wheel speeds for various operating modes of the continuously variable transmission of Fig. 3; Fig. Figure 5 is a schematic view of another continuously variable transmission used in the powertrain of Fig. 2 may be included; Fig. Figure 6 is a graphical representation of continuously variable power source speeds and vehicle wheel speeds for various operating modes of the continuously variable transmission of Fig. 5; Fig. Figure 7 is a schematic view of another continuously variable transmission used in the powertrain of Fig. 2 may be included; and Fig. Figure 8 is a graphical representation of adjustable energy source speeds and vehicle wheel speeds for various operating modes of the continuously variable transmission of Fig. 7.

[0012] Similar reference numerals in the different drawings indicate similar elements.

[0013] The following describes one or more embodiments of the disclosed multimode continuously variable transmission ("MIVT"), as shown in the accompanying drawing figures briefly described above. Various modifications to the exemplary embodiments may be appreciated by those skilled in the art.

[0014] In various known designs, one or more planetary gear sets may be used to combine the output power of a continuously variable power source (“IVP”) and a motor (e.g., an internal combustion engine). For example, in a planetary gear set, a first component of the gear set (e.g., a ring gear) may receive power from the motor, a second component of the gear set (e.g., a sun gear) may receive power from the IVP, and a third component of the gear set (e.g., a planet carrier) may sum the power from the motor and the IVP at the output of the gear set. (For convenience of designation, “component” may be used herein, particularly in the context of a planetary gear set, to refer to an element for transmitting power, such as a sun gear, a ring gear, or a planet carrier.)) It is clear that such a design can allow for an essentially infinite (and continuously variable) number of gear ratios for the planetary gear set. For example, for a given engine speed, a specific gear ratio can be set by varying the speed of the IVP with respect to the engine speed.

[0015] In certain cases, it may be useful to facilitate a zero-drive mode for a vehicle (or other machine) in which the output speed of the vehicle's wheels (or other machine output) reaches zero speed without stopping the engine or delivering torque to the wheels. In this way, for example, vehicle power can be used to hold a vehicle stationary. Such a condition can be achieved, for example, with a planetary gear train designed as described above. For example, if an engine rotates a sun gear at a first positive speed and an IVP is commanded to rotate a ring gear at an equivalent negative speed, an associated planet carrier (which may be connected, for example, to a differential input shaft) may not rotate at all.Furthermore, if the electric motor rotates at a slightly different (and opposite) speed than the engine, the vehicle may enter a "crawl" mode, in which the vehicle moves very slowly but with high wheel torque. Zero-drive and crawl modes are particularly useful for heavy-duty work vehicles, such as the one shown in . Fig. 1, which are used in the agricultural, construction, and forestry industries. As wheel speed increases, the vehicle can then eventually enter a normal drive mode. In conventional designs, each of these modes can be a split-path mode, in which power transfer is split between a purely mechanical path from the engine and the mixed path through the IVP.

[0016] One issue with continuously variable powertrains can concern the relative efficiency of power transfer in different operating modes. For example, it is clear that mechanically transferring power from an engine to a transmission (i.e., mechanical path transfer) can be a highly efficient mode of power transfer, whereas power transfer through an IVP can be less efficient (e.g., because the mechanical power must be converted into electrical or hydraulic energy by a first machine, transferred to a second machine, and then converted back into mechanical power). Accordingly, there may be significant motivation to utilize the mechanical path more extensively than the IVP route (e.g., by increasing the engine's speed).However, this increased use of the mechanical path can also drive up the required IVP speed for zero-power and creep modes of operation, as these modes may require a near or actual speed match between the IVP and engine speeds. This can lead to increased wear on associated gears and other parts (e.g., a planetary gear component receiving power from the IVP and associated bearings), even to the point of part failure. Furthermore, achieving suitable speeds may require a significant increase in the size and power of a relevant IVP from a preferred size and power. Among other advantages, the MIVT disclosed herein can address these issues.For example, by selectively utilizing clutches and / or brakes, an MIVT can allow greater utilization of a mechanical path while avoiding the need for excessive IVP speeds in zero-power and creep modes.

[0017] As will be apparent from the present discussion, an MIVT can be used advantageously in a wide variety of environments and with a wide variety of machines. For example, with reference now to Fig. 1 an MIVT may be included in the drive train 12 of a vehicle 10. In Fig. In Figure 1, the vehicle 10 is depicted as a tractor. However, it is understood that other configurations may be possible, including the vehicle 10 being configured as another type of tractor, a logging tractor, a road grader, or one of various other work vehicle types. Furthermore, it is understood that the disclosed IVT may also be used in non-work vehicles and non-vehicle applications (e.g., stationary powertrains).

[0018] As also noted above, an advantage of the disclosed MIVT is that it can enable operation of a vehicle in a variety of propulsion modes (e.g., zero-power mode, creep mode, and branch-path mode) that can utilize various combinations of engine and IVP power. For example, by using various clutches and / or brakes associated with one or more planetary gear sets, an MIVT can enable engine power to be isolated from an IVT output even while the engine continues to operate.For example, if an IVP drives a first component of a planetary gear train and a motor drives a second component of the planetary gear train, in certain embodiments and operating modes, a clutch may disconnect the operating motor from the second component, and a brake may stop rotation of a third component of the transmission, allowing power to be delivered only from the IVP through the reduction gear of the planetary gear train. In this way, for example, only electric power (or hydraulic power, etc.) may be used to propel (or sustain) the vehicle 10 in certain operating modes, while combined electric and motor power may be used to propel (or sustain) the vehicle 10 in other operating modes.As such, among other advantages, an MIVT can avoid certain previous limitations on the proportion of energy that can be diverted from a motor through an electrical path (or hydraulic path, etc.).

[0019] With reference to Fig. 2, various components of an exemplary powertrain 12 are shown. For example, the engine 14 may supply mechanical power (e.g., via a rotating shaft) to an MIVT 16. The engine 14 may also supply mechanical power to an IVP 18, which may include one or more IVP machines (e.g., an electric motor and generator, or a hydraulic machine with a hydraulic motor and an associated pump). The MIVT 16 may additionally receive mechanical power from the IVP 18.

[0020] The MIVT 16 may include various clutches 20 and brakes 22, which may be controlled by various actuators 24. The actuators 24, in turn, may be controlled by a transmission control unit ("TCU") 26, which may receive various inputs from various sensors or devices (not shown) via a CAN bus (not shown) of the vehicle 10. The MIVT 16 may include one or more output shafts 28a for transferring mechanical power from the MIVT 16 to various other components (e.g., a differential driveshaft). In certain embodiments, additional transmissions (e.g., a range transmission) may be disposed between the MIVT 16 and other parts of the vehicle 10 (e.g., a differential driveshaft). In certain embodiments, the IVP 18 may also provide power directly to other parts of the vehicle 10 (e.g., via a direct IVP driveshaft 28b).

[0021] With reference to Fig. 3, various internal components of an embodiment of the MIVT 16 are presented. It should be noted that the schematic representations of the Fig. 3 shown gearbox (and also the one in Fig. 5 and Fig. 7) illustrate exemplary implementations in a simplified form for clarity and thus cannot show all of the components associated with the illustrated transmission. The engine 14 may include an internal combustion engine 14a that can deliver mechanical power directly to the shaft S1. (A "direct" power transfer, as used herein, may include the transfer of power through a direct physical connection, a one-piece design, or via a simple intervening element such as an idler gear or planetary gear. In contrast, for example, a power transfer between a ring gear of a planetary gear set and a sun gear of the planetary gear set via a planetary gear carrier (and associated planet gears) of the planetary gear set may not be considered "direct".) The IVP 18 may include an electric generator 30 and electric motor 32.The electric generator 30 can receive mechanical power via a gear 36 and gear 34 attached to the shaft S1 and can generate electrical energy for transmission to the electric motor 32. The electric motor 32 can convert the received electrical power into mechanical power, thereby rotating the shaft S2.

[0022] Although specific terms such as "generator" and "motor" may be used herein to describe various exemplary configurations, it is understood that these (and similar) terms may be used to generally refer to an electrical machine capable of operating either as a generator or as a motor. For example, electrical generator 30 may sometimes operate as an electric motor, and electric motor 32 may sometimes operate as a generator. Likewise, it is understood that the actual operating modes of other continuously variable power sources may vary similarly from those explicitly described herein.

[0023] In certain embodiments, the MIVT 16 may include a planetary gear train 38 and a double planetary gear train 40. In certain embodiments, the planetary gear train 38 and the double planetary gear train 40 may be configured to sum mechanical power from the motor 14a and the IVP 18. Through the use of one or more associated clutches and / or brakes, the MIVT 16 may provide an output using only power from the IVP 18 in certain operating modes.

[0024] The planetary gear set 38 may, for example, include a planetary carrier 42 that supports planetary gears 44 that can mesh with the sun gear 46 and the ring gear 48. A drive clutch 50 may be configured to engage the planetary carrier 42 and the sun gear 46 (e.g., based on signals from the TCU 26) to control the power transfer between these gears. For example, in a fully engaged state, the drive clutch 50 may lock the planetary carrier 42 to the sun gear 46. As shown in Fig. 3, the motor 14a may directly drive the planetary gear carrier 42 via the shaft S1. Accordingly, engagement of the clutch 50 may effectively lock the sun gear 46 to the shaft S1 and the output of the motor 14a. A reversing brake 52 may be anchored to a fixed housing of the MIVT 16 (or other feature) and may be configured to engage to stop the rotation of the ring gear 48.

[0025] In certain embodiments, an output component of the planetary gear set 38 may directly transmit power to an input component of the double planetary gear set 40. For example, the sun gear 46 may be integrally connected to the ring gear 54, thereby directly connecting an output of the planetary gear set 38 (i.e., the sun gear 46) to an input of the double planetary gear set 40 (i.e., the ring gear 54).

[0026] The double planetary gear set 40 may also receive input power from the IVP 18. For example, the electric motor 32 may drive the rotation of shaft S2 in conjunction with the attached gear 56. The gear 56 may mesh with the gear 58 attached to the shaft S1, and the gear 58 may directly transmit power to (e.g., may be integrally formed with) the sun gear 60 of the double planetary gear set 40. The sun gear 60 may mesh with planet gears 62 (one is shown), which may be directly connected to the planet gears 64 (one is shown), with both sets of planet gears 62 and 64 being carried by a planet gear carrier 66. Each of the planet gears 64 may mesh with one of the planet gears 78, which in turn may mesh with the ring gear 68. The planet carrier 66 connected to the ring gear 68 (e.g.via the planetary gears 64 and 78) and the creep brake 70 may be anchored to a fixed housing of the MIVT 16 (or other feature) and configured to engage the ring gear 68 to stop rotation of that component.

[0027] The planetary gear carrier 66 may provide mechanical output from the double planetary gear set 40 for transmitting mechanical power to various parts of the vehicle 10. For example, the planetary gear carrier 66 may be integrally connected to a pinion gear 72 that may mesh with a gear along a idler shaft S3. In certain embodiments, an additional gear 74 (e.g., a range gear) may be disposed between the MIVT 16 and other parts of the vehicle 10 (e.g., a differential drive shaft ("DDS")) or may be included as part of the MIVT 16. In this manner, for example, various gear shifts may be implemented beyond the continuously variable baseline gear ratio provided by the MIVT 16.

[0028] In certain operating modes, the MIVT 16 (as in Fig. 3) may provide zero-power and creep modes of operation in which only power from the IVP 18 is delivered to the wheels of the vehicle 10. For example, the input clutch 50 may be released and the brake 70 engaged with the ring gear 68 (or in certain configurations, with the ring gear 54 (not shown)). This may accordingly disconnect the motor 14a from the double planetary gear set 40 while providing a fixed ring gear (e.g., ring gear 68) about which the components of the double planetary gear set 40 may rotate. Mechanical power from the IVP 18 may be delivered to the sun gear 60, which may drive the planet carrier 66 around the ring gear 68. This, in turn, may cause rotation of the drive pinion 72, which is driven by the IVP 18 but not by the engine 14a, which may enable drive of the wheels of the vehicle 10 (e.g., via the transmission 74) using only power from the IVP 18.

[0029] Next, to shift the vehicle out of this IVP-only mode, a reverse process to that described above may be performed. For example, clutch 50 may be engaged, connecting motor 14a to sun gear 46 and ring gear 54. Simultaneously (or nearly simultaneously), creep brake 70 may be released, allowing the dual planetary gear set 40 to provide an output at pinion gear 72 representing a sum of the power from the IVP 18 and motor 14a. It will be appreciated that this selective use of two of a set of friction elements (e.g., clutches and brakes) may generally facilitate transition between different operating modes for the vehicle 10.

[0030] In certain embodiments, it may be advantageous to effect a transition between operating modes (e.g., between an IVP-only creep mode and a combined drive mode) in different ways. For example, with clutch 50 engaged, it may be possible to rotate sun gear 60 (via IVP 18) at a speed such that ring gear 68 substantially stops, even without the use of brake 70. To provide more seamless switching between operating modes, it may be advantageous to switch between drive and creep modes at such a point. In this way, for example, brake 70 can be engaged and clutch 50 can be released with minimal disruption to vehicle operation. A similar seamless shift point can also be obtained for switching from creep to drive mode and may represent a target point for these (and other) shifts.However, it will be appreciated that in certain embodiments, ramp (or other) modulation of the clutch 50 (or other components) may be used.

[0031] In certain applications, it may be desirable to operate the vehicle 10 in reverse, whether in a crawl mode, drive mode, or other mode. In the MIVT 16, as shown in Fig. 3, it may be possible, for example, to engage a reversing brake 52 for this purpose.

[0032] With reference to Fig. 4 is a graphical representation of the relationship between the vehicle wheel speed (in kilometers per hour) and the speed of the electric motor 32 (in revolutions per minute) for the design of the MIVT 16 in Fig. 3. Various curves are presented for the operation of the vehicle 10, wherein various range gears (not shown) are engaged within the transmission 74. It is clear that the Fig. 4 The sizes represented are only examples.

[0033] For example, line 80 may represent operation of the vehicle in a creep mode (e.g., using only electric power). It can be seen that at zero engine speed, the vehicle speed may be zero, with the non-zero engine speed being directly proportional to the vehicle speed. In creep mode (e.g., with the brake 70 engaged, the input clutch 50 disengaged, and an engaged A-range gear (not shown) in the transmission 74), the vehicle 10 may accelerate to a transition point. For example, as described above, the vehicle 10 may accelerate to a point where, based on the engine speed and relevant gear ratios, the ring gear 68 may be relatively stationary, even without engagement of the brake 70.At this (or another) point, brake 70 may be released and clutch 50 engaged, shifting the vehicle relatively seamlessly into branch-path drive. Motor 32 may then begin to decelerate along line 82, with the vehicle speed (now driven in branch-path mode by both motor 32 and motor 14a) increasing, even as the speed of motor 32 changes direction (i.e., changes from positive rotation to negative rotation).

[0034] Continuing, the vehicle 10 may be shifted from the A-range gear in the transmission 74 to a higher B-range gear (not shown). To continue the acceleration of the vehicle 10, it may now be appropriate to switch the direction of rotation of the motor 32, thereby jumping from the negative rotation and line 82 to the positive rotation and line 84. The motor 32 may then be decelerated again, followed by another shift to a higher C-range gear in the transmission 74 and a corresponding jump for the motor 32 from line 84 to 86. By modulating the rotation of the motor 32 in this manner, shifting between different range gears of the transmission 74 can be achieved with the same reduction ratio at the start of the shift (e.g., at the end of the A-range gear) as at the end of the shift (e.g., at the beginning of the B-range gear).(It will be appreciated that a reduction ratio may be the product of the gear ratios of the planetary gears 38 and 40 and the engaged gear (e.g., the A-range gear) of the transmission 74.)

[0035] Various advantages can be gained from the design of Fig. 3 (and others provided for by this disclosure). For example, in the interpretation of Fig. 3 (and other designs), the transmission 74 may be located downstream of the planetary gear sets 38 and 40. This may enable the use of a full range of torques and speeds obtained at the output of the MIVT 16 (i.e., as they may result from various combinations of the power of the motor 14a and motor 32) with any portion or gear of the transmission 74. For example, an electric-only mode (or any of a variety of branch-path modes) may be used with any portion or gear of the transmission 74. This may provide significant flexibility during vehicle operation.

[0036] In addition, the interpretation of Fig. 3 (or in other configurations), a split-mode drive may be implemented using a relatively simple planetary path, which may, among other benefits, reduce wear, extend service life, and reduce costs for the MIVT 16. This may be particularly useful, for example, for applications where a large portion of the operating time is expected to be spent in split-path mode (e.g., for various agricultural tasks performed by the vehicle 10). In split-path mode, for example, power from the engine 14a may be delivered through the clutch 50 to the ring gear 54, and power from the engine 32 may be delivered to the sun gear 60. These components (i.e., ring gear 54 and sun gear 60) may collectively cause the rotation of the planet carrier 66 (via the planet gears 62), which in turn may cause the rotation of the pinion gear 72 and the corresponding transfer of power into the transmission 74.In contrast, in an electric-only mode, power can be delivered from the motor 32 to the sun gear 60 and then in turn to the planet gears 62, planet gears 64 (which can be directly connected to the gears 62 or formed integrally with them), and planet gears 78. With the ring gear 68 locked by the brake 70, power can then flow from the planet gears 62, 64, and 78 to the planet carrier 66, and so on. In this way, it is clear that fewer gear meshes can be used in the branch-path mode than in the electric-only mode, which may represent a relative improvement in energy transfer efficiency and may also result in a relative reduction in part wear.

[0037] With reference to Fig. 5, an additional exemplary embodiment of an MIVT 16 is now presented. As in Fig. 5, an MIVT 16 may include a planetary gear train 98 and a double planetary gear train 100. An internal combustion engine 14a may directly drive both a hydraulic drive (e.g., a pump 102 and a motor 104) and a shaft S4, and a hydraulic drive motor 104 may drive the shaft S5. The planetary gear train 98 may include a sun gear 106, a planet carrier 108, and a ring gear 110. A drive clutch 112 may be configured to engage the shaft S4 to connect the output of the motor 14a to the sun gear 106. A creep clutch 114 may be configured to engage both the planet carrier 108 and the ring gear 110, potentially locking the planet carrier 108 and the ring gear 110 together. A reversing brake 116 may be configured to engage the ring gear 110.Accordingly, in certain configurations, the reversing brake 116 may be used to reverse the output of the planetary gear set 98 with respect to the output of the motor 14a.

[0038] The planetary gear 98 may include an output that is directly connected to an input of the double planetary gear 100 (e.g., directly toothed or integral therewith). For example, as shown in Fig. 5, the planetary gear carrier 108 may be an output component for the planetary gear set 98 and may mesh directly with the planetary gear carrier 122 of the double planetary gear set 100 (i.e., via gears 118 and 120). Furthermore, in certain configurations, this input to the gear set 100 may rotate directly with another component of the transmission 100. For example, the planetary gear carrier 122 may be formed as a single component with the ring gear 124 so that both components rotate in unison.

[0039] The motor 104 may provide an additional input for the double planetary gear set 100. For example, the motor 104 may supply input power to both sun gears 126 and 128 via shaft S5. The double planetary gear set may also include, for example, a ring gear 130 and planet carrier 134.

[0040] In this interpretation, similar to the above discussion regarding the embodiment of Fig. 3, various clutches and brakes associated with the MIVT 16 can be used to switch between different operating modes for the vehicle 10. For example, when the input clutch 112 is disengaged, no power can be transferred from the operating engine 14a to the planetary gear set 98 or double planetary gear set 100. Further, with the creep clutch 114 and the reversing brake 116 engaged, the gear 118 can be locked. Accordingly, the engagement of the creep clutch 114 and the reversing brake 116 can prevent rotation of both the ring gear 124 and the planet carrier 122 (although the planet gears 132 can continue to rotate around the carrier 122). In this manner, even though the motor 14a may be operating, the double planetary gear set 100 can only transfer power from the motor 104 to the drive pinion 140 (e.g., in either a forward or reverse creep mode).

[0041] In certain embodiments, additional transmission components may be provided to facilitate various types of vehicle operations and modes of operation. For example, a lower clutch 136 and an upper clutch 138 may be included within the dual planetary gear set 100, with the upper clutch 138 configured to engage both the ring gear 130 and the input pinion gear 140, and the lower clutch 136 configured to engage both the planetary carrier 134 and the input pinion gear 140. Accordingly, in creep mode or other modes of operation, the clutches 136 and 138 may be selectively activated to adjust the effective overall gear ratio of the two planetary gear sets 98 and 100.

[0042] In certain embodiments, a transmission 142 may be arranged between the double planetary gear 100 and other parts of the vehicle 10 (e.g., a DDS) and may include various gears (e.g., range gears). In certain embodiments, the Fig. 5 may allow transition between fixed gear ratios within the transmission 142 (and in the context of the continuously variable gear ratio provided by the hydraulic machine 102, 104) without necessarily changing the direction of rotation for the motor 104. For example, the vehicle 10 may begin operation at zero speed with the motor 14a disconnected from the transmission (via the clutch 112) and the clutch 114 and brake 116 engaged. The motor 104 may accordingly provide the sole power to the drive pinion 140 (and the gearshift 142). The motor 104 may be started in the positive direction (for a positive-direction creep mode) or in the negative direction (for a negative-direction creep mode).Assuming, for example, an initial positive direction of motion, the rotation of the motor 104 (and thereby of the shaft S5) may accelerate in the positive direction, causing the sun gears 126, 128 to also accelerate. Initially, for example, the lower clutch 136 may be engaged, transferring power from the sun gear 128 via the planetary gear carrier 134 to the input pinion 140. Within the transmission 142, a first low-range gear may be engaged, completing the power transfer path from the motor 104 to other parts of the vehicle 10 (e.g., a differential drive shaft).

[0043] At a particular speed of the motor 104, depending on the particular associated gear ratios, the ring gear 110 may tend to be relatively stationary even when the brake 116 is not engaged. As also indicated above, this may provide a useful point at which to transition between operating modes (e.g., creep mode and branch path mode) or different gears (e.g., range gears within the transmission 142). Accordingly, continuing the above example, once the motor 104 has accelerated through the creep mode to such a speed-matched point (or at various other times), the reversing brake 116 may be released and the input clutch 112 may be engaged. This may provide a mechanical transmission path for power from the motor 14a to the double planetary gear set 100.At the same time (or nearly so), the lower clutch 136 can also be released and the upper clutch 138 can be engaged. Due to the in . Fig. 5, it may not be necessary at this point to reverse the direction of rotation of the motor 104 in order to continue forward acceleration of the vehicle 10 (as is the case, for example, for the configuration shown in Fig. 3 may be the case). In certain embodiments, after engagement of clutch 112 (i.e., entry into a split-path mode), the rotational speed of engine 104 may simply be slowed down from the rotational speed at the time of the transition, with the vehicle 10 being accelerated accordingly.

[0044] With reference to Fig. For example, Figure 6 shows a graph of the relationship between the vehicle wheel speed (in kilometers per hour) and the speed of the engine 104 (in revolutions per minute) for the design of the MIVT 16 in Fig. 5. Various curves are presented for the operation of the vehicle 10, wherein different gears (e.g., range gears) are engaged within the transmission 142. It is clear that the Fig. 6 represented sizes are only examples.

[0045] For example, line 150 may represent operation of the vehicle 10 in a creep mode (e.g., using only hydraulic power). It will be appreciated that at zero engine speed, the vehicle speed may be zero, with non-zero engine speed being directly proportional to vehicle speed. In creep mode (e.g., with the brake 116 and creep clutch 114 engaged, the drive clutch 112 disengaged, and an engaged A-range gear (not shown) in transmission 142), the vehicle may accelerate to a transition point. In certain embodiments, this may be a point at which, based on the engine speed and relevant gear ratios, the ring gear 110 may be relatively stationary, even without engagement of the brake 116. At this (or another) transition point, the brake 116 may be disengaged and the clutch 112 engaged, shifting the vehicle into split-mode drive.The motor 104 may then begin to slow down along line 152, with the vehicle speed (now driven by both the motor 104 and the motor 14a) increasing, even as the speed of the motor 104 changes direction (i.e., changes from positive rotation to negative rotation).

[0046] Continuing, the vehicle may shift from the previous A-range gear in transmission 142 to a higher B-range gear (not shown). To continue accelerating the vehicle 10, it may again be appropriate to switch the direction of rotation of the motor 104 (but not immediately the direction of rotation of the motor 104) and engage an appropriate B-range gear (with or without switching clutches 136 and 138). The motor 104 may then accelerate along line 154, accelerating the vehicle 10 accordingly.

[0047] With reference to Fig. 7, an additional exemplary embodiment of the MIVT 16 is now presented. As in Fig. 7, an internal combustion engine 14a may supply mechanical power to an electric generator 172, which may supply electrical power to an electric motor 174 via a power cable 176. The engine 174 may drive (e.g., via direct gearing) the rotation of the sun gear 182 of the double planetary gear train 178. The train 178 may also be configured to receive mechanical power from the engine 14a via shaft S7, with the input clutch 196 configured to engage both the shaft S7 and the sun gear 180. A planetary gear carrier 184 including planetary gears 192 may be directly connected to (e.g., integral with) a ring gear 190, which itself may be configured to receive power from the sun gear 182 via a planetary gear carrier 186. A ring gear 188 may mesh with the planetary gears 192.Furthermore, the planetary gear carrier 186 may form an output component of a gear set 178 and may, for example, be directly connected to an input component of a transmission 202 (e.g., formed integrally therewith).

[0048] As with other embodiments discussed herein, a number of clutches and brakes may be incorporated within the MIVT 16 (e.g., as shown in Fig. 7) can allow useful transition between various operating modes, including a creep mode powered only by motor 174 and a split-path mode powered by both motor 174 and motor 14a. For example, clutch 196 can engage shaft S7 and sun gear 180 to transfer power from motor 14a to dual planetary gear set 178. Similarly, clutch 198 can engage both ring gear 188 and planet carrier 184 to lock these components together. Finally, reversing brake 200 can engage ring gear 188 to stop rotation of this gear.

[0049] In this regard, it will be appreciated that clutch 198, brake 200, and clutch 196 may be selectively engaged (and released) to provide various operating modes. For example, when clutch 196 is released and both clutch 198 and reversing brake 200 are engaged, vehicle 10 may be propelled using only the power of engine 174. Likewise, other operating modes may be possible with various other configurations (e.g., various combinations in which two of clutch 198, brake 200, and clutch 196 are engaged).

[0050] With reference to Fig. 8 now also shows, for example, a graphical representation of the relationship between the vehicle wheel speed (in kilometers per hour) and the speed of the engine 174 (in revolutions per minute) for the design of the MIVT 16 in Fig. 7. Various curves are presented for the operation of the vehicle 10, wherein various gears (e.g., range gears) are engaged within the gearshift 202. It is clear that the Fig. 8 represented sizes are only examples.

[0051] For example, line 212 may represent operation of the vehicle 10 in a creep mode (e.g., using only electric power). It can be seen that at zero engine speed, the vehicle speed may be zero, with the non-zero engine speed proportional to the vehicle speed. In creep mode (e.g., with the reversing brake 200 and clutch 198 engaged, the drive clutch 196 disengaged, and an engaged A-range gear (not shown) in transmission 202), the vehicle 10 may accelerate to a transition point. For example, the vehicle 10 may accelerate to a point where, based on the engine speed and relevant gear ratios, the ring gear 188 may be relatively stationary even without engagement of the brake 200. At this (or another) point, the brake 198 may be disengaged and the clutch 196 engaged, shifting the vehicle into split-mode drive.At this time (or near this time), motor 174 may reverse its direction of rotation, transitioning from line 212 to line 214. The vehicle 10 may accordingly continue to accelerate (now driven by motor 174 and motor 14a), with the vehicle speed increasing, even as the speed of motor 174 changes direction (i.e., changes from negative rotation to positive rotation). Similar shifts may also be effected, for example, to a B-range wheel (not shown) from the A-range wheel (not shown) by transitioning motor 174 from line 214 to line 216, etc.

[0052] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms "a," "an," and "the," as used herein, are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, it is to be understood that any use of the terms "comprises" and / or "comprising" in this specification specifies the presence of stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

Claims

[1] Continuously variable transmission, comprising: a first planetary gear (38) comprising a first gear component and comprises a second transmission component; a double planetary gear train (40) comprising an input component, an output component, a third gear train component, and a fourth gear train component; a clutch (50); and a first brake (70); wherein the first transmission component receives a first mechanical input power for the first planetary gear set (38) from a motor (14a); wherein the third transmission component receives a second mechanical input power for the double planetary gear (40) from a continuously variable power source (18); wherein the second transmission component directly transmits energy to the input component of the double planetary gear (40); wherein the clutch (50) is configured to engage the first transmission component and the second transmission component to control the power transfer between the first transmission component and the second transmission component; wherein the first brake (70) is configured to engage the fourth transmission component to stop rotation of the fourth transmission component; wherein the output component is configured to receive mechanical power directly from the input component and the fourth transmission component; wherein the double planetary gear (40) is designed to sum mechanical power from the motor (14) and the continuously variable energy source (18) and to supply the summed power to the output component, characterized bythat during operation of the motor (14), a controlled actuation of one or more of the first brake (70) and the clutch (50) causes the output component to be supplied with power from the continuously variable energy source (18) but not from the motor (14). [2] Continuously variable transmission according to claim 1, further comprising: a fifth gear component included in the first planetary gear (38); and a second brake (52) configured to engage the fifth transmission component to stop rotation of the fifth transmission component; wherein controlled actuation of the second brake (52) causes reverse rotation of the second transmission component and the input component. [3] Continuously variable transmission according to claim 1 or 2, wherein the first transmission component comprises a first planetary gear carrier (42) carrying one or more first planetary gears (44). [4] Continuously variable transmission according to one of claims 1 to 3, wherein the second transmission component comprises a first sun gear (46). [5] Continuously variable transmission according to one of claims 1 to 4, wherein the input component comprises a first ring gear (54). [6] Continuously variable transmission according to one of claims 1 to 5, wherein the third transmission component comprises a second sun gear (60). [7] Continuously variable transmission according to one of claims 1 to 6, wherein the fourth transmission component comprises a second ring gear (68). [8] Continuously variable transmission according to one of claims 1 to 7, wherein the output component of the double planetary gear (40) comprises a second planet carrier (66) carrying one or more second planet gears (62, 64), the one or more second planet gears (62, 64) meshing with one or more of the input component and the fourth transmission component. [9] A continuously variable transmission according to any one of claims 1 to 8, wherein the continuously variable power source (18) comprises one or more of a pair of electric machines (30, 32) and a hydrostatic machine.

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