Electric motor transmission

Abstract

A vehicle power train is provided, comprising an electric motor, a final drive, and a two-degree-of-freedom gear system configured to transmit power from the electric motor to the final drive, wherein the gear system includes a one-way mechanism and a mechanical friction brake connected to the gear system. The power train further includes a control system. With this power train, it is possible to perform power running, coasting without motor drag, and braking by regenerative braking. Further, a method for controlling the braking mode of a vehicle equipped with such a power train is provided.

Description

Technical Field

[0001] The present disclosure generally relates to an electric motor transmission having two degrees of freedom, and more specifically to an electric motor gear system having two degrees of freedom arranged to enable coasting (or inertial running) as well as regenerative braking.

Background Art

[0002] Current electric vehicles use a direct drive connection to the final drive or an electric motor implemented in a "one-way clutch" or "one-way clutch" gear system. Direct drive is a common case for automobiles and motorcycles, and regenerative braking is possible, but there is a drawback that the motor is always "engaged" with the final drive, so the motor is always dragged and an efficient coasting mode cannot be achieved.

[0003] One-way clutch gear connection, which is a common case for electric bicycles, enables coasting without dragging the motor, but regenerative braking is prohibited.

[0004] In order to provide an energy-efficient transmission for electric vehicles, a transmission is needed that can coast without dragging the motor and can convert kinetic energy into electrical energy during braking.

Summary of the Invention

[0005] The present disclosure provides a powertrain (power transmission mechanism) including a gearing system having two degrees of freedom. The powertrain of the present disclosure, more specifically the gearing system of the present disclosure, is arranged to enable coasting as well as regenerative braking.

[0006] The present disclosure provides a powertrain of a vehicle including an electric motor, a final drive, and a gear system having two degrees of freedom including at least three components configured to rotate one with respect to the other. The gear system may be configured to transmit power from the electric motor to the final drive, and the gear system includes a one-way mechanism connected to one of at least three rotating components of the gear system, and the one-way mechanism may be configured to reduce the two degrees of freedom by restricting the rotation of one component along a first direction. During the power running mode of the powertrain, the one-way mechanism is configured to allow free rotation along a second opposite direction of one component, and during the coasting mode of the powertrain, the resistance of the electric motor is avoided. The powertrain may further include a mechanical friction brake connected to the gear system via one of at least three components, and the mechanical friction brake is configured to reduce the two degrees of freedom by restricting the rotation of the component to which the mechanical friction brake is connected during the braking mode of the powertrain, causing the movement of the electric motor, thereby regenerating the energy by the electric motor.

[0007] Optionally, the mechanical friction brake is connected to the gear system and not connected to the final drive.

[0008] Optionally, the one-way mechanism is an overrunning clutch.

[0009] Optionally, the gear system includes a planetary gear (gear), and the at least three components may include a sun gear rotatably connected to the electric motor and at least one planetary gear (gear), and the at least one planetary gear (gear) is rotatably connected to a planetary carrier.

[0010] Optionally, the one-way mechanism may be a one-way bearing incorporated as part of the planetary carrier. The one-way bearing is configured to allow rotation of the planetary carrier in a first direction and prevent rotation of the planetary carrier in a second direction, where the second direction is opposite to the first direction.

[0011] Optionally, the mechanical friction brake is connected to the planetary carrier, and the mechanical friction brake is configured to decelerate the rotation of the planetary carrier, and as a result, mechanically force the rotation of the electric motor through the forced rotation of the sun gear, thereby enabling regenerative braking.

[0012] Optionally, the mechanical friction brake includes a disc brake.

[0013] Optionally, the gear system consists of a differential gear system, and the at least three components include a first side gear rotatably connected to the electric motor and a horizontal planetary gear (gear), the horizontal planetary gear (gear) is rotatably connected to a rack carrier, and the horizontal planetary gear (gear) is further rotatably connected to a second side gear.

[0014] Optionally, the one-way mechanism is a one-way bearing incorporated as part of the second side gear. The one-way bearing is configured to allow rotation of the second side gear in a first direction and prevent rotation of the second side gear in a second direction, where the second direction is opposite to the first direction.

[0015] Optionally, the mechanical friction brake consists of a disc brake connected to the second side gear. The disc brake is configured to mechanically force the rotation of the electric motor through the forced rotation of the first side gear by decelerating the rotation of the second side gear, thereby enabling regenerative braking.

[0016] The present disclosure further provides a vehicle gearing system comprising an electric motor, a final drive, and a two-degree-of-freedom gear system consisting of at least three components configured to rotate one with respect to the other, the gear system being configured to transmit power from the electric motor to the final drive.

[0017] The gear system includes a one-way mechanism connected to one of at least three rotating components of the gear system, the one-way mechanism being configured to reduce the two degrees of freedom by restricting the rotation of one component along the first direction during the power running mode of the powertrain, while the one-way mechanism is configured to allow free rotation of one component along a second opposite direction during the coasting mode of the powertrain, thereby avoiding the drag of the electric motor. The powertrain may further include a mechanical friction brake connected to the gear system via one of at least three components, the mechanical friction brake being configured to reduce the two degrees of freedom by restricting the rotation of the component to which the mechanical friction brake is connected during the braking mode of the powertrain, causing the movement of the electric motor, and thereby regenerating the energy by the electric motor. The powertrain may further include a control system configured to control the amount of power supplied by the electric motor during the running mode and the amount of negative torque applied by the electric motor during the regenerative braking mode. The control system includes a processor configured to detect the braking mode; define a setpoint value (fixed point, set value) in advance based on (i) the gear ratio of the vehicle and (ii) a parameter that can be changed according to the required regeneration ratio; calculate a process value based on the ratio of the speed of the motor to the speed of the final drive; determine the amount of negative torque required for equivalence between the process value and the setpoint value, the negative torque being configured to be applied by the electric motor during the regenerative braking mode.

[0018] Optionally, the required regeneration ratio is determined by at least one of the state of charge (SOC) of the battery / capacitor, power rating, driving speed, motor load, terrain, temperature, or a combination thereof.

[0019] The present disclosure may further include a method for controlling a braking mode in a vehicle, the vehicle comprising an electric motor, a final drive, and a two-degree-of-freedom gear system consisting of at least three components configured to rotate one with respect to the other, the gear system being configured to transmit power from the electric motor to the final drive. The gear system includes a one-way mechanism connected to one of at least three rotating components of the gear system, the one-way mechanism being configured to reduce the two degrees of freedom by restricting the rotation of one component along a first direction during the power running mode of the powertrain, while the one-way mechanism is configured to allow one component to rotate freely along a second opposite direction during the coasting mode of the powertrain, thereby avoiding the drag of the electric motor. The vehicle may further include a mechanical friction brake connected to the gear system via one of at least three components, the mechanical friction brake being configured to reduce the two degrees of freedom by restricting the rotation of the component to which the mechanical friction brake is connected during the braking mode of the powertrain, causing the movement of the electric motor, thereby regenerating energy by the electric motor and the processor.

[0020] The method includes detecting a braking mode, predefining a setpoint value based on (i) the gear ratio of the vehicle and (ii) a parameter that can be changed according to the required regeneration ratio, calculating a process value based on the ratio of the motor speed to the final drive speed, and determining the amount of negative torque applied by the electric motor during the regenerative braking mode, which is required for the equivalence between the process value and the set value.

[0021] As an option, detecting the braking mode includes determining the rotation of the motor and further determining that no throttle is being applied by the user.

[0022] As an option, calculating the process value further includes detecting the motor speed via respective speed sensors and detecting the final drive speed.

[0023] As an option, the method further includes calculating an error indicating the difference between the process value and the setpoint value.

[0024] As an option, the required regeneration ratio is determined by at least one of the state of charge (SOC) of the battery / capacitor, rated output, travel speed, motor load, terrain, temperature, or a combination thereof.

Brief Description of the Drawings

[0025] Some non-limiting exemplary embodiments or features of the disclosed subject matter are shown in the following drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 5C

Figure 6A

Figure 6B

Figure 6C

Figure 7A

Figure 7B

Figure 7C

Figure 7D

Figure 8

[0026] Here, referring specifically and in detail to the drawings, it is emphasized that the specific matters shown are examples and for illustrative discussion of embodiments of the present disclosure. In this regard, by explaining together with the drawings, it will be clear to those skilled in the art how embodiments of the present disclosure can be implemented.

[0027] The same, overlapping, equivalent, or similar structures, elements, or components that appear in one or more of the drawings are generally labeled with the same reference numerals, and optionally, additional letters or characters may be added to distinguish similar entities or variations of entities, and may not be repeatedly labeled and / or described. References to previously presented elements are implied without necessarily further citing the drawings or descriptions in which they appear.

[0028] The dimensions of the components and features shown in the figures are selected for the convenience of presentation or clarity, and are not necessarily shown to scale or as true perspective views. For convenience or clarity, some elements or structures are not shown, or are shown only partially, and / or are shown from different viewpoints or perspectives.

Mode for Carrying Out the Invention

[0029] The present disclosure provides a transmission or gear system configured to be implemented in a vehicle having an electric motor, and further configured to enable coasting as well as regenerative braking during operation of the vehicle. Such a transmission system (transmission system, power transmission system) can provide an energy-efficient vehicle that benefits from coasting without dragging the motor, reduces waste of kinetic energy during such coasting, and also benefits from regenerating electrical energy during braking operation, which is also energy-efficient.

[0030] The present disclosure provides two aspects. The first is the mechanical aspect of the gear system, the purpose of which is to connect between the electric motor and the final drive (final drive device, final reduction mechanism), for example, the wheels of the vehicle, during the driving mode, disconnect the connection between the electric motor and the final drive during the coasting mode, and finally, gradually reconnect between the electric motor and the final drive (final drive device) during the braking mode.

[0031] The second aspect of the present disclosure is the control aspect, the purpose of which is to determine the amount of braking (negative) torque applied to the electric motor of the vehicle to decelerate the vehicle and regenerate energy.

[0032] Therefore, in the braking mode, the moving final drive, for example, the moving wheels, are connected to the electric motor, and since the motor resists its movement via the control system, the final drive or the wheels decelerate, thereby decelerating the vehicle.

[0033] As used herein, the term "vehicle" refers to any vehicle equipped with an electric motor. The vehicle may be a fully electric vehicle, a hybrid vehicle such as a hybrid car, or a manual vehicle with an electric motor assist such as a manual bicycle with a motor assist.

[0034] The terms "gear", "gear system", and "transmission" are used interchangeably throughout this specification.

[0035] Next, refer to FIG. 1, which schematically shows a powertrain of a vehicle including a gear system having two degrees of freedom according to some embodiments of the present disclosure. According to the present disclosure, via the powertrain, the vehicle can have at least three operating modes including power running, coasting, and regenerative braking. The present disclosure provides a powertrain 10 having two degrees of freedom, and this powertrain 10 can include an electric motor 12 configured to convert electric power or electrical energy into mechanical power or mechanical energy, a final drive 20, and a gear system 14 having two degrees of freedom. The gear system 14 may be configured to transmit mechanical power from the electric motor 12 to the final drive 20. According to some embodiments, the powertrain 10 may further include a one-way mechanism 16. The one-way mechanism 16 may typically be an overrunning clutch, a one-way clutch, or a one-way bearing that can be incorporated as part of the gear system 14. The one-way mechanism 16 may be configured to reduce the degrees of freedom of the gear system 14 for the power running mode. According to some embodiments, the powertrain 10 may further include a mechanical friction brake 18 connected to the gear system 14. According to the present disclosure, the mechanical friction brake 18 is not connected to the final drive 20. The mechanical friction brake 18 may be controlled by the user to partially or completely reduce the degrees of freedom of the gear system 14 for the regenerative braking mode. In some embodiments, the mechanical friction brake 18 may be configured as any one of a disc brake, a drum brake, a block brake, or other friction brake mechanisms, or any combination thereof.

[0036] According to some embodiments, the powertrain 10 can further include a control system 22 configured to control the operation of the electric motor 12 during various operating modes of the powertrain 10. In some embodiments, the control system 22 may include a processor 24, which is configured to determine the amount of negative torque that can be applied by the electric motor 12 during the regenerative braking mode. According to some embodiments, the gear system 14 may be composed of a planetary gear (gear), a differential gear (gear), and any other similar gear system having two degrees of freedom.

[0037] According to some embodiments of the present disclosure, the mechanical friction brake 18 may be connected to an element of the gear system 14 rather than the final drive so that the powertrain 10 enables regenerative braking while further enabling the powertrain 10 to coast through the one-way mechanism 16.

[0038] According to some embodiments, the control system 22 may be configured to receive various inputs, typically speed-related, such as the speed of the electric motor 12, the speed of the final drive 20, the speed of any component of the gear system or the mechanical friction brake 18, and / or any combination thereof. In some embodiments, the inputs received by the control system 22 may be received from different sensors that can be connected to different elements of the powertrain 10. The received inputs may be analyzed by at least one processor 24 that may be incorporated as part of the control system 22 according to a braking mode control algorithm described later with respect to FIG. 4. In some embodiments, the control system 22 may be configured to analyze the received input data and provide instructions to the powertrain 10 to control the amount of electric power that the electric motor 12 should apply for each specific operating mode (e.g., power running, coasting, and regenerative braking).

[0039] Refer to FIG. 2, which schematically shows an isometric view of a transmission system according to some embodiments of the present disclosure. According to some embodiments, the transmission system of the present disclosure may be a gear system 100 having two degrees of freedom and consisting of planetary gears. The planetary gear system 100 may be composed of a sun gear 101 and one or more pinion gears or planetary gears (gears) 102 configured to rotate relative to the rotation of the sun gear 101. In some embodiments, the sun gear 101 may be connected to an electric motor, for example, the electric motor 12 (FIG. 1), which rotates relative to the vehicle chassis represented by the reference numeral 107. According to some embodiments, the gear system 100 may further include a planetary carrier 122, which is configured to rotate relative to the vehicle chassis 107 along a one-way bearing 103 (an example for the one-way mechanism 16 in FIG. 1) such that the rotation of the planetary carrier 122 is restricted in a single direction. In some embodiments, the gear system 100 may include a ring gear 105 that can be attached to a final drive (for example, the final drive 20 in FIG. 1). In some embodiments, the final drive may be a wheel, such as a bicycle wheel.

[0040] In some embodiments, since one component of the gear system 100 can rotate two other components, the gear system may have two degrees of freedom. In this case, as an example, during different operating modes, the sun gear 101 serves as the input, and the output may be either the ring gear 105, the planetary carrier 122, or both, depending on the degrees of freedom enabled or restricted by the gear system 100.

[0041] According to some embodiments, when the rotation direction of the planetary carrier 122 can be realized (effective) by the one-way bearing (bearing) 103, the rotation of the sun gear 101 can rotate one or more planetary gears (gears) 102, thereby rotating the planetary carrier 122. The rotation of one or more planetary gears (gears) 102 due to the rotation of the sun gear 101 may also rotate the ring gear 105.

[0042] According to some embodiments, the gear system 100 may include a mechanical friction braking system 104 (an example for the mechanical friction brake 18 in FIG. 1). In some embodiments, the mechanical friction braking system 104 may include a disc brake 114 and a caliper 124. In some embodiments, the disc brake 114 may be attached to the planetary carrier 122 such that the disc brake 114 and the planetary carrier 122 rotate together as one element. In some embodiments, the disc brake 114 may be attached to the planetary carrier 122 via bolts, screws 134, or any other fastening means.

[0043] In some embodiments, the caliper 124 may be fixed to the chassis 107 of the electric vehicle. The caliper 124 may be composed of two brake pads respectively disposed on one of two opposite sides of the disc brake 114. When the user actuates the friction braking system 104, for example, via a brake handle or a brake pedal, the caliper 124 may be clamped to the disc brake 114. According to some embodiments, either the brake handle or the brake pedal by which the friction braking system 104 is operated may be an inherent component of the vehicle and may not require modification after the gear system 100 is implemented in a vehicle having an electric motor.

[0044] According to some embodiments, in the "power running (driving)" mode, the electric motor is being powered and thus rotating, i.e., the electric motor 12 and the sun gear 101 subordinate thereto are rotating, which means that during "power running", the sun gear 101 is the input of the gear system 100. In one example, the electric motor 12 may rotate in a direction opposite to the forward driving direction of the final drive 20. During the "power running" mode, the planetary carrier 122 may be prevented from rotating in the same direction as the electric motor 12 by a one-way mechanism 16, e.g., a one-way bearing 103, and thus the planetary carrier 122 is forced to be stationary. Accordingly, the degree of freedom of the gear system 100 is reduced by one. That is, all torque is transmitted from the electric motor 12 and its subordinates, such as the sun gear 101, through one or more planetary gears 102 to the final drive 20 and its subordinates, such as the ring gear 105. In the running mode or the power running mode, the ring gear 105 serves as the output of the gear system 100.

[0045] According to some embodiments, in the "coasting" mode, the ring gear 105 rotates without receiving power from the electric motor 12, so the ring gear 105 is the input of the gear system 100. When the ring gear 105 rotates, one or more planetary gears 102 can be rotated, and those planetary gears 102 can freely rotate the planetary carrier 122 in the direction enabled and indicated by the one-way bearing 103. In this example, the rotatable direction is the forward running direction of the final drive 20. Thus, during the coasting mode, torque is not transmitted to the sun gear 101 through the planetary carrier 122, allowing the sun gear 101 and thereby enabling the electric motor 12 connected to the sun gear 101 to be stationary.

[0046] According to some embodiments, in the "braking" mode, mechanical braking force may be applied to the planetary carrier 122 by the user. The user can operate the mechanical friction braking system 104, for example, by using a brake handle or a brake pedal. In some embodiments, the brake handle or the brake pedal may be connected to the mechanical friction braking system 104, which may be composed of a caliper 124 and a disc brake 114. In the "braking" mode, since the ring gear 105 rotates without receiving power from the electric motor 12, the ring gear 105 serves as the input of the gear system 100. When the ring gear 105 rotates, it may rotate one or more planetary gears 102. In the "braking" mode, since the planetary carrier 122 is restricted by the friction braking system 104, the planetary carrier 122 may not be able to rotate freely. In this way, torque is transmitted from the still-rotating ring gear 105 due to the vehicle's movement, through one or more planetary gears 102, through the sun gear 101 to the electric motor 12, rotating the sun gear 101 and thus the electric motor 12.

[0047] In some embodiments, as soon as the user stops the operation of the electric motor 12, for example, by stopping the operation of a throttle handle or a throttle pedal, the operating mode changes from "driving" to "coasting". For example, when the electric motor 12 decelerates, the planetary carrier 122 begins to rotate. Since the disc brake 114, which is part of the mechanical friction braking system 104, is connected to the planetary carrier 122 such that the disc brake 114 and the planetary carrier 122 rotate integrally, when the user operates the mechanical friction braking system 104, the caliper 124 may be clamped on both sides of the disc brake 114, and mechanical braking force may be applied to the planetary carrier 122.

[0048] Since the disk brake 114 and the planetary carrier 122 are connected to form a single unit with each other, for example, when the user presses the brake handle, the caliper 124 decelerates the free rotation of the disk brake 114 and the planetary carrier 122. Thus, torque is transmitted from the ring gear 105, which is still rotating due to the movement of the vehicle, through one or more planetary gears 102 to the sun gear 101 and then to the electric motor 12, rotating the sun gear 101 and thus the electric motor 12. A control system, such as control system 22, can apply a negative torque to the sun gear 101 to the electric motor 12 in order to decelerate the vehicle and regenerate energy. That is, since the planetary carrier 122 is forcibly decelerated by the mechanical friction braking system 104, the gear system 100 is reduced to one degree of freedom and the ring gear 105 rotates, so the ring gear 105 forcibly rotates the sun gear 101 and thus the electric motor 12 through the rotation of one or more planetary gears 102. Forcing the sun gear 101 and thus the electric motor 12 to rotate by the rotation of the ring gear 105 does not supply power to the electric motor 12 (like in the driving mode) to rotate the electric motor 12, but rather mechanically forces the electric motor 12 to rotate, which has the potential to regenerate energy. In some embodiments, the regenerated energy can be stored in an energy storage device, such as a battery or a capacitor, for later use.

[0049] According to the present disclosure, the disc brake 114 is not used to directly decelerate the vehicle, but rather to restrict two degrees of freedom. Thereby, as will be described in detail with respect to FIG. 4, most of the braking energy is regenerated while only a small amount of energy is wasted by friction and heat. In the gear system 100 shown in FIG. 2, by connecting the disc brake 114 to one of the elements of the planetary gear system, for example, the planetary carrier 122, when the brake is applied, the electric motor 12 is forced to rotate not by being electrically powered, but rather by a reduction in one of the two degrees of freedom. Thereby, the electric motor 12 generates electrical energy during the braking mode.

[0050] According to some embodiments, during the driving mode, the user can operate the throttle, and the electric motor 12 can generate positive torque according to the position of the throttle. During the coasting mode, the user releases the throttle, and the electric motor 12 finally decelerates and completely stops. And finally, during the braking mode, the user can activate the friction braking (brake) system 104 to decelerate the elements of the transmission system connected to the friction braking system 104. For example, according to FIG. 2, the element decelerated by the friction braking system 104 is the planetary carrier 122. When the planetary carrier 122 is decelerated, the electric motor 12 rotates. The control system 22 can detect that the electric motor 12 is rotating by an external force rather than a throttle command, and can respond by applying a controlled negative torque to the electric motor 12, causing the electric motor 12 to function as a generator and enabling regenerative braking.

[0051] Therefore, in order for the control system 22 to properly control the operation of the electric motor 12, it is necessary to determine and distinguish such modes while switching the operation modes.

[0052] Next, refer to FIG. 3 schematically showing a mode detection method according to some embodiments of the present disclosure. In some embodiments, the mode detection method 300 may be executed by the control system 22, for example, via the processor 24. In some embodiments, the mode detection method 300 may include determining (302) whether the electric motor 12 is rotating by sensing the electric motor speed via, for example, a speed sensor that may be connected to the electric motor 12. If the control system 22 or the processor 24 determines that the electric motor 12 is not rotating, the control system 22 can identify that the vehicle is in the coasting mode (306). If the control system 22 or the processor 24 determines that the electric motor 12 is rotating, a determination regarding the throttle position is required (304). If the control system 22 or the processor 24 determines that the electric motor 12 is rotating and the throttle position is not equal to "0", that is, when the throttle is actuated, the control system 22 or the processor 24 can identify that the vehicle is in the driving mode or the power driving mode (308). However, if the control system 22 or the processor 24 determines that the electric motor 12 is rotating and the throttle position is equal to "0", the control system 22 or the processor 24 may identify that the vehicle is in the braking mode (310). This is because the electric motor 12 is rotating, but not due to the actuation of the throttle. For example, the throttle position is not zero, but due to an external force, that is, the actuation of a friction braking system, such as the friction brake 18 (FIG. 1) or the friction system 104 (FIG. 2).

[0053] As a safety measure, an ON / OFF sensor can be added to the brake handle / pedal to force the throttle position to zero every time the brake is applied. In such a case, once the mechanical brake is applied, when the brake sensor senses the activation of the mechanical brake, any other commands, such as the operation of the electric motor 12 via the throttle, are invalidated by the control system 22 of FIG. 1. That is, regardless of the user's throttle position, when the brake sensor detects the activation of the mechanical brake, the control system 22 enters the braking mode (310), and the vehicle begins to decelerate.

[0054] Now, refer to FIG. 4, which is a schematic diagram of a braking mode control algorithm according to an embodiment of the present disclosure. According to an embodiment of the present disclosure, in order to provide a smooth braking motion, the amount of negative torque that should be continuously applied by the electric motor 12 can be determined by the control system 22, for example, via the processor 24, according to the braking mode control algorithm 400.

[0055] In some embodiments, the braking mode control algorithm 400 may be a feedback loop. The braking mode control algorithm 400 may include calculating a loop process value (PV) 406, which may represent the ratio between the motor speed and the final drive speed and may be calculated according to Equation (1): (1) PV = ωm / ωd Here, ωm represents the speed of the motor ωd indicates the speed of the final drive.

[0056] In some embodiments, the motor speed may be provided by the motor speed sensor 416, and the speed of the final drive may be provided by the final drive speed sensor 422. The ratio between the motor speed and the final drive speed may be calculated in operation 418 according to Equation (1).

[0057] In some embodiments, the braking mode control algorithm 400 may include setting a loop set point (SP) ratio 402 having a value calculated according to Equation (2): (2) SP = Regen × Gear Here, Regen represents a parameter with a value less than 1 indicating the ratio of the motor speed to the final drive speed. Gear represents the gear ratio of a two - degree - of - freedom gear system and, in the driving mode, represents the gear ratio when the degrees of freedom are completely reduced. According to some embodiments, when “Regen” has a value close to “1”, this indicates that most of the kinetic energy is regenerated by the electric motor 12, and when “Regen” has a value close to “0”, this indicates that most of the kinetic energy is dissipated as heat by the mechanical braking system 104. In some embodiments, in order to provide an energy - efficient gear system, “Regen” should be a number less than 1 but as close to 1 as possible.

[0058] In some embodiments, the energy regenerated by the electric motor 12 can be stored in an energy storage device such as a battery or a capacitor. When the energy storage device reaches or is about to reach its maximum capacity, or when the regenerative power is close to the maximum rating specified by the manufacturer of any component of the electrical system, “Regen” can be set to a low value, as a result, the regenerative braking power can be minimized and the mechanical braking power can be maximized. That is, in some embodiments, “Regen” can be changed or modified during vehicle operation by the control system 22, for example, via the processor 24, to conform to various system limitations.

[0059] In some embodiments, "Regen" may be a parameter that can be varied according to the required regeneration ratio, which can be changed by the control system 22 based on the state of charge (SOC) of the battery / capacitor, rated power, drive speed, motor load, terrain, temperature, or any combination thereof. Other and / or additional parameters may affect "Regeneration".

[0060] In some embodiments, the braking mode control algorithm 400 may include receiving an error 408 by a controller 410 that may be included as part of the control system 22. The error 408 may be calculated by subtracting the process value (PV) from the set point (set value, SP). In response to receiving the error 408, the controller 410 controls the amount of negative torque 412 applied by the electric motor 414 (e.g., electric motor 12, FIG. 1) to achieve equality between the SP ratio and the PV ratio, and as a result, the error 408 may be made equal to zero.

[0061] The amount of negative torque applied by the electric motor 414 (e.g., electric motor 12) is proportional to the negative error 408. The greater the negative error 408, the greater the negative torque applied by the electric motor 414. When the error 408 is positive, i.e., when the absolute value of the PV is less than the absolute value of the SP, no negative torque is applied, but no positive torque is applied either. That is, during the braking mode, only negative torque should be applied by the electric motor to decelerate the vehicle while regenerating energy, so the maximum positive torque defined by the control system 22 during the braking mode is "0".

[0062] In some embodiments, the greater the braking pressure applied by the user, the greater the decrease in the speed of the planetary carrier 122. Since the motor speed increases as the planetary carrier speed decreases, the decrease in the planetary carrier speed may be reflected as an increase in PV. In response, the controller 410 can increase the negative torque on the motor 414, thereby reducing the PV value and increasing the braking force to achieve an equal value between PV and SP.

[0063] Conversely, the lower the braking pressure applied by the user, the lower the speed of the planetary carrier 122. The lower the speed of the planetary carrier 122, the more likely it is to be reflected as a decrease in PV, which may cause the controller 410 to reduce the negative torque on the motor 414 and thereby reduce the braking force.

[0064] For example, the planetary gear (gear) type gear system 100 can be represented by the following equation (3): (3)(R + S)×Tc = R×Tr + Ts×S Where R represents the number of teeth of the ring gear, S represents the number of teeth of the sun gear, Tc represents the number of turns of the planetary carrier, Tr represents the rotational speed of the ring gear, Ts represents the rotational speed of the sun gear. In this example, the gear system can implement the following number of sun gear teeth and ring gear teeth: S = 16, R = 64. Set the reduction ratio to "-4", that is, in the driving mode, while the final drive rotates once in the first direction, the sun gear rotates 4 times in the second direction opposite to the first direction, that is, Gear = -4. Optionally, the coasting speed may be 200 RPM, that is, ωd = 200. Since the operating mode is coasting, the electric motor is stationary and does not rotate, so ωm = 0. Therefore, according to Equation (3), when the ring speed is 200 rpm and the motor speed is 0 rpm, the planetary carrier speed (Tc) is 160 rpm. In this example, "Regen" is defined as follows: Regen = 0.9. According to this embodiment, when the user applies the brake, the planetary carrier, for example, planetary carrier 122 decelerates, and the electric motor 414 or the electric motor 12 starts to rotate. The control system 22 can adjust the motor braking torque (i.e., negative torque) so that the electric motor rotates at a speed that satisfies the SP requirement. (2) SP = Regen × Gear = 0.9 × (-4) = -3.6 To meet the requirement of SP, in order to avoid the existence of error 408, PV must be equal to SP: (1) PV = ωm / ωd = ωm / 200 = -3.6 => ωm = -720 Therefore, the required braking mode motor speed (revolutions per minute) for the vehicle speed in this embodiment is -720 RPM, which means that the electric motor needs to rotate at a speed of 720 RPM in the direction opposite to the rotation direction of the ring (e.g., final drive 20). Therefore, according to Equation (3), when the ring speed (revolutions per minute) is 200 RPM and the motor speed (revolutions per minute) is -720 RPM, the planetary carrier speed (revolutions per minute) is 16 RPM.

[0065] When the user applies more force to the brake, the planetary carrier 122 reduces its speed, and as a result, the electric motor 12 increases its speed, for example, up to -730 RPM. Therefore, the control system 22 needs to increase the brake torque to return the motor speed to -720 RPM in order to continuously meet the SP requirement by maintaining the equality between PV and SP. When the user reduces the pressure on the brake, the planetary carrier increases its speed, and as a result, the motor reduces its speed, for example, down to -710 RPM. Therefore, the control system reduces the brake torque to return the motor speed (revolution speed) to -720 RPM in order to continuously meet the SP requirement. In this way, the greater the pressure applied to the brake by the user, the greater the brake torque increased by the control system 22, and the smaller the pressure applied to the brake, the smaller the brake torque applied to the control system 22, enabling an intuitive braking operation by the user.

[0066] In some embodiments, the control system 22 responds to changes in the electric motor speed by adjusting the brake / negative torque applied to the electric motor 12 in a continuous manner in order to maintain satisfaction of the SP requirement throughout the operation of the vehicle, for example, via the processor 24.

[0067] In some embodiments, the proportion of energy lost in a friction brake, for example, the mechanical friction braking system 104, is proportional to the planetary carrier speed in "braking mode" versus the planetary carrier speed in "coasting mode", which is 10% in this example: 16 / 160 = 10%. That is, only 10% of the braking energy is dissipated by the friction brake, and the remaining energy can be used for regenerative braking.

[0068] Therefore, in order to enable adjustment of the brake torque by the control system 22, by adjusting the value of "Regen" to be as close to 1 as practically possible while keeping "Regen" less than 1, the energy loss due to the friction brake can be minimized, meaning that the gear system 100 of the present disclosure is highly energy-efficient.

[0069] The controller 410 or the control system 22 determines the amount of negative torque applied to the electric motor 12 based on the value of the error 408, i.e., proportional to the amount by which the PV is higher than the SP, for example via the processor 24. Therefore, the value of "Regen" must be less than 1. That is, a negative error 408 is required to generate negative torque. If the value of "Regen" is equal to 1, the PV ratio will not be greater than the SP ratio, the error 408 will not be negative, and no braking torque will be applied to the electric motor 12.

[0070] According to some embodiments, the electric motor 12 may have a non-zero minimum braking torque, and the braking torque below that minimum value may be achieved by applying a gentle pressure to the braking system, and thus only a partial torque is transmitted from the final drive 20 to the electric motor 12. According to the above example, when coasting at 200 RPM, the user may apply the brakes very gently, thereby decelerating the planetary carrier from the coasting speed of 160 RPM to a slightly lower speed, e.g., 150 RPM, and slowly rotating the electric motor at -50 RPM according to Equation (3). In such a scenario, since the absolute value of the PV is smaller than the absolute value of the SP, the error 408 is positive. Therefore, the control system 22 applies zero negative torque and no energy is regenerated. However, since there is some internal friction in the electric motor 12, the vehicle is gently decelerated in proportion to the speed of the electric motor controlled by the amount of braking force applied by the user.

[0071] In some embodiments, the vehicle does not require a predetermined sensor for detecting the brake handle / pedal position. Instead, the adjustment of the braking torque applied to the electric motor 12 can be determined by the control system 22 in response to the amount of braking applied by the user on the brake handle / pedal, as described herein. Therefore, there is no need to modify the existing braking mechanism.

[0072] According to some embodiments, when starting the braking process, the electric motor needs to spin up from zero to the braking RPM (e.g., -720 RPM according to the above example). The increase in the speed (rotation speed) of this electric motor may be gradual and may be controlled by the amount of braking force applied by the user, as described herein with respect to the braking mode control algorithm 400. That is, unlike some current designs that include a solenoid acting as an electromagnetic clutch, which is an instantaneous engagement of the motor that is an uncomfortable "ON / OFF" or "0 / 1" operation, the present disclosure provides a gradual increase in motor speed that allows for a smooth engagement of the electric motor 12 in accordance with user input, which is more consistent with the natural user operation of current braking systems.

[0073] According to some embodiments of the present disclosure, the powertrain system of the present disclosure provides continuously variable braking torque from zero negative torque to the maximum negative torque capacity of the electric motor 12 by responding to the braking pressure applied by the user in a seamless and intuitive manner via the braking mode control feedback loop 400.

[0074] Next, refer to FIGS. 5A - 5C which schematically show a cross - sectional view, an isometric view with a partial hub, and an isometric view with a complete hub of a transmission system implemented in an electric bicycle (bike) according to an embodiment of the present disclosure. In some embodiments, the transmission system of the present disclosure can be implemented as part of a geared hub motor system 500 of an electric bicycle. In some embodiments, the electric bicycle geared hub motor system 500 may be composed of an electric motor rotor 501, and this electric motor rotor may be attached to a gearring system having 2 degrees of freedom, which may be similar to the gearring system 100 (FIG. 2). The gear system may include a sun gear 511, at least one planetary gear 502, for example two planetary gears 502, and a planetary carrier 522. The final drive 20 may be disposed within and composed of a ring gear 505 attached thereto within a hub or case 515. In some embodiments, the motor rotor 501 may be attached to the sun gear 511. In some embodiments, the planetary carrier 522 may rotate around a static shaft 507 corresponding to the chassis of the electric bicycle via a one - way mechanism, for example a one - way bearing 503. In some embodiments, a friction brake mechanism consisting of a disk brake 514 may be attached to the planetary carrier 522 via, for example, bolts, rivets, screws 534, or any other fastening means.

[0075] In some embodiments, the hub or cover 515 is configured to cover the components of the gear system while maintaining the disk brake 514 as the only component outside the space defined by the hub 515.

[0076] In some embodiments, the electric bicycle geared hub motor system 500 may further include a bearing 560 that is part of the hub 515 and to which the disk brake 514 can be connected to the planetary carrier 522. The bearing 560 allows the disk brake 514 to rotate with the planetary carrier 522 as a single unit that can rotate independently of the hub 515.

[0077] Next, refer to FIGS. 6A - 6C which schematically show a cross-sectional view and an isometric side view of a transmission system implemented in an electric two-wheeler according to an embodiment of the present disclosure. In some embodiments, the transmission system 660 can be implemented as part of the rear hub of an electric two-wheeler that is externally powered by a mid-drive motor system 600. According to some embodiments, the two-degree-of-freedom gear system 660 implemented as part of the electric two-wheeler motor system 600 is implemented in a form similar to a power differential, but includes the same basic principles of the transmission system of the present disclosure and enables not only free coasting but also regenerative braking.

[0078] In some embodiments, the electric two-wheeler system 600 may include a motor 670 (FIG. 6B) that can be externally connected to a sprocket 601 (FIG. 6A) via, for example, a chain 672 or any other mechanism. The sprocket 601 may be attached to a gear system 660 via a first side gear 611. The rotation of the first side gear 611 is enabled by a first side gear bearing 661. The rotation of the first side gear 611 causes the rotation of a horizontal planetary gear (gear) 602 attached to a rack carrier 622. The rack carrier 622 may be attached to a final drive 605. The rotation of the horizontal planetary gear (gear) 602 may cause the rotation of the rack carrier 622. The rotation of the horizontal planetary gear (gear) 602 may be enabled via a bearing 662. The rotation of the horizontal planetary gear (gear) 602 may further cause the rotation of a second side gear 604. In some embodiments, the second side gear 604 may be attached to a one-way bearing 603 configured to direct the rotation of the second side gear 604 in only one direction. The second side gear 604 may rotate relative to a stationary shaft or chassis 607. The rotation of the rack carrier 622 with respect to each of the first side gear 611 and the second side gear 604 may be enabled by a bearing 682. In some embodiments, a disc brake 614 may be attached to the second side gear 604 via, for example, bolts, rivets or screws 634.

[0079] The power differential gear system shown in FIGS. 6A - 6C can be represented by the following equation (4): (4) Trc=(T1 + T2) / 2 Here,[[]]END]] T1 represents the rotational speed of the first side gear (e.g., the first side gear 611), T2 represents the rotational speed of the second side gear (e.g., the second side gear 604), Trc represents the rotational speed of the rack carrier (e.g., the rack carrier 622).

[0080] During the drive mode, the electric motor 670 can supply power to operate the rotation of the sprocket 601, which can rotate the first side gear 611. The second side gear 604 may be prevented from moving during the drive mode due to the rotation limit indicated by the one-way bearing 603. In some embodiments, the one-way bearing 603 may enable the second side gear 604 to rotate only in a single direction, e.g., along the direction in which the first side gear 611 rotates. Thus, the rotation of the first side gear 611 can rotate one or more horizontal planetary gears 602, rotate the rack carrier 622, and thereby rotate the final drive 605 and the wheel 680.

[0081] During the coast mode, the wheel 680 and the final drive 605 rotate together with the rack carrier 622, and torque is transmitted to the second side gear 604 in the direction allowed by the one-way bearing 603 via the horizontal planetary gear (gear) 602. Thus, the second side gear 604 and the disk brake 614 connected to the second side gear 604 rotate integrally. Therefore, due to the rotation of the horizontal planetary gear (gear) 602, the first side gear 611 and the sprocket 601 directly connected to the first side gear 611 are stationary, thereby enabling the motor 670 to be stationary.

[0082] During the braking mode, the final drive 605 and the wheel 680 rotate together with the rack carrier 622. Since the brake is applied during the braking mode, the movement of the disk brake 614 and the second side gear 604 connected to the disk brake 614 is suppressed, and torque is transmitted to the first side gear 611 via the horizontal planetary gear 602, and as a result, to the sprocket 601, thereby causing the motor 670 to rotate.

[0083] In the braking mode, the motor 670 does not rotate by the power supplied to the motor 670 as in the driving (traveling) mode. Instead, in the braking mode, the motor 670 is mechanically forced to rotate, thereby regenerating energy.

[0084] In some embodiments, the braking mode control feedback loop 400 (FIG. 4) may be further implemented with respect to the power differential gear system of FIGS. 6A - 6C. The differential topology may implement a reduction ratio of 2 according to Equation (4), i.e., in the traveling mode, for one rotation of the final drive in the first direction, the first side gear (T1) rotates two times in the same direction, i.e., Gear = 2.

[0085] Optionally, coasting may be performed at 200 RPM, i.e., ωd = 200.

[0086] Since the operating mode is coasting, the electric motor stops and does not rotate, thus ωm = 0.

[0087] According to Equation (4), when the rack carrier rotational speed (Trc) is 200 rpm and the first side gear rotational speed (T1) is 0 rpm, the second side gear rotational speed (T2) is 400 rpm.

[0088] In this example, "Regen" is defined as follows: Regen = 0.9.

[0089] According to this example, when the user applies the brake, the second side gear (T2) decelerates, the electric motor starts to rotate, and the control system, e.g., the control system 22 (FIG. 1) implemented by the braking mode control feedback loop 400, can adjust the motor braking torque (i.e., negative torque) so that the electric motor 670 rotates at a speed that meets the SP requirement.

[0090] According to Equation (2), in this example, SP = Regen × Gear = 0.9 × 2 = 1.8.

[0091] To meet the requirements of the SP, the PV must be equal to the SP to avoid the presence of error 408: PV = ωm / ωd = ωm / 200 = 1.8 => ωm = 360.

[0092] Therefore, the required braking mode motor speed (revolutions per minute) per vehicle speed in this embodiment is 360 RPM, which means that the motor rotates at a speed of 360 RPM in the same direction as the rack carrier.

[0093] Therefore, according to Equation (4), when the rack carrier speed (Trc) is 200 rpm and the first side gear rotation speed (T1) is 360 rpm, the second side gear rotation speed (T2) is 40 rpm.

[0094] In some embodiments, the percentage of energy lost in a friction brake, such as a mechanical friction braking system 104, in this case a disc brake 614, is proportional to the "braking mode" speed of the second side gear (T2) to the "coasting mode" speed of the second side gear (T2), which is 10% in this example: 40 / 400 = 10%. That is, only 10% of the braking energy is dissipated by the friction brake, and the remaining energy can be used for regenerative braking.

[0095] Next, refer to FIGS. 7A - 7D, which are schematic diagrams of some configurations of a transmission system that enable a driving mode, a coasting mode, and a regenerative braking mode according to embodiments of the present disclosure. Each of configurations 7A, 7B, 7C, and 7D may incorporate a gear system having two degrees of freedom, and this gear system may include a one-way mechanism, such as a one-way (one-way) bearing, configured to limit the rotation of one of the elements of the gear system during the driving mode, while further including a braking system configured to limit the rotation of one of the elements of the gear system during the braking and regenerative braking modes.

[0096] In some embodiments, the configuration of FIG. 7A corresponds to a planetary gear (gear) transmission system similar to the planetary gear (gear) system 100 shown in FIG. 2 and the gear system 500 of FIGS. 5A-5C. The configuration 7A includes a motor 12 configured to rotate the sun gear 101, and the sun gear 101 can rotate one or more planetary gears 102 and rotate the planetary carrier 122 and the ring gear 105 according to the associated operating mode. According to the configuration 7A, the planetary carrier 122 includes a one-way bearing 103 through which the planetary carrier 122 can rotate relative to the vehicle chassis 107.

[0097] In some embodiments, the configuration of FIG. 7B corresponds to a differential gear transmission system as shown in FIGS. 6A-6C. The configuration 7B includes a one-way bearing 603 through which the second side gear 604 can rotate relative to the vehicle chassis 607.

[0098] In some embodiments, the configuration of FIG. 7C corresponds to a planetary gear (gear) transmission system, and this planetary gear (gear) transmission system includes a planetary carrier 122 including a one-way bearing 103 through which the planetary carrier can rotate relative to the sun gear 101.

[0099] In some embodiments, the configuration of FIG. 7D corresponds to a differential gear transmission system, and this differential gear transmission system includes a rack carrier 622 including a one-way bearing 603 through which the rack carrier 622 can rotate relative to the first side gear 611.

[0100] Now, refer to FIG. 8, which is a table summarizing the details of the transmission system configurations of FIGS. 7A-7D that enable all of the driving mode, coasting mode, and regenerative braking mode according to the embodiments of the present disclosure. According to some embodiments, Table 800 summarizes the characteristics of the different transmission systems of FIGS. 7A-7D that enable the driving mode, coasting mode, and regenerative braking mode.

[0101] According to some embodiments, in Table 800, "motor" represents a component of the transmission system corresponding to the motor, or a component directly connected to the motor. "Final drive" represents a component of the transmission system corresponding to the final drive, or a component directly connected to the final drive. "One-way" represents a component of the transmission system that is forced to rotate in only one direction with respect to any other component of the transmission system during the driving mode. "Braking component" represents a component of the transmission system that is connected to a mechanical braking system and whose rotational speed is forcibly reduced when the mechanical braking system is activated.

[0102] For example, Configuration "A" of Table 800 shows a transmission system implementing a planetary gear (gear) as illustrated in FIGS. 7A and 8. In Configuration "A", the electric motor 12 is represented, and the component connected to the electric motor 12 is the sun gear 101 (similar to the sun gear 501 in FIG. 5A), and its speed is represented by "Ts". According to Configuration "A", the component representing the final drive is the ring gear 105 (similar to the ring gear 505 in FIG. 5A), and its speed is represented by "Tr". According to Configuration "A", during the drive mode, the component that is forced to move in only one direction is the planetary carrier 122 (similar to the planetary carrier 522 in FIG. 5A). According to Configuration "A", the planetary carrier 122 is forced to move in one direction with respect to the vehicle chassis 107 (similar to the chassis 507 in FIG. 5A). Therefore, the speed of the planetary carrier 122 can be equal to zero or greater than zero, "Tc≧0". In some embodiments, the one direction of the planetary carrier 122 may be indicated by a one-way bearing 103 (similar to the one-way bearing 503 in FIG. 5A). In some embodiments, the braked component in the planetary gear (gear) system of Configuration "A" is the planetary carrier 122. Therefore, in order to cause the rotation of the electric motor 12 for energy regeneration, the speed of the planetary carrier 122 can be set to zero (Tc→0). The control parameters of Configuration "A" that can be implemented by the braking mode control algorithm 400 and Equation (3) may be Gear = (-R) / S, and 0 < Regen < 1.

[0103] According to some embodiments, Configuration "B" of Table 800 represents a transmission system implementing a differential gear, as illustrated in FIGS. 7B and 8 and shown in detail in FIGS. 6A-6C. In Configuration "B", the electric motor 12 is represented, and the component connected to the electric motor 12 is the first side gear 611 with a speed represented by "T1". According to Configuration "B", the component representing the final drive is the rack carrier 622, and its speed is represented by "Trc". According to Configuration "B", during the driving mode, the component that is allowed to move in only one direction is the second side gear 604. According to Configuration "B", the second side gear is forced to move in one direction relative to the vehicle chassis 607. Therefore, the speed of the second side gear 604 may be equal to zero or greater than zero, "T2≧0". In some embodiments, the one direction of the second side gear 604 may be indicated by the one-way bearing 603. In some embodiments, the braked component in the differential gear system of Configuration "B" is the second side gear 604. Therefore, in order to generate the rotation of the electric motor 12 via the first side gear 611 for energy regeneration by the electric motor 12, the rotation speed of the second side gear 604 can be set to zero (T2→0).

[0104] The control parameters of Configuration "B" that can be implemented by the braking mode control algorithm 400 and Equation (4) are Gear = 2, and 0 < Regen < 1.

[0105] According to some embodiments, Configuration "C" of Table 800 represents a transmission system that implements a planetary gear system with a dual gear ratio, as shown in FIGS. 7C and 8. According to Configuration "C", the component of the transmission system connected to the motor 12 is the sun gear 101, and the sun gear speed is represented by "Ts". The component connected to the final drive is the ring gear 105, and its speed is represented by "Tr". In Configuration "C", unlike Configuration "A", the one-way bearing 103 is connected to the planetary carrier 122, and the planetary carrier 122 can rotate along the one-way bearing with respect to the sun gear 101, as shown in FIG. 7C, rather than with respect to the chassis 107 as in FIG. 7A. That is, according to Configuration "C", the planetary carrier 122 with a speed represented by "Tc" is allowed to rotate only in one direction with respect to the sun gear 101, for example, via the one-way bearing 103, thereby enforcing the condition Tc≧Ts. In Configuration "C", the component connected to the mechanical braking system is the planetary carrier 122. Therefore, in order to rotate the electric motor 12 for energy regeneration by transmitting torque to the electric motor 12, the speed of the planetary carrier 122 can be set to zero (Tc→0). The control parameters of Configuration "C" that can be implemented as part of the braking mode control algorithm 400 and Equation (3) may be Gear=-R / S, and 0<Regen<1.

[0106] According to Configuration "C", during the driving mode, the one-way bearing 103 allows the sun gear 101 to rotate the planetary carrier in the same direction at a 1:1 ratio. Therefore, according to Equation (3), the planetary carrier 122 can rotate the ring in the same direction at a 1:1 ratio, that is, a 1:1 ratio between the sun gear and the final drive can be implemented. For example, according to Equation (3), when the motor 12 or the sun gear 101 rotates at a speed of 200 RPM, Ts = Tc = Tr = 200 RPM.

[0107] According to Configuration "C", during the coasting mode, the planetary carrier 122 rotates freely. Therefore, the ring 105 can rotate the planetary gear (gear) 102, and the planetary carrier 122 rotates according to Equation (3), thereby enabling the sun gear 101 and thus the motor 12 to be stationary. In an embodiment of the planetary gear (gear), as in the example regarding Configuration 7A where the number of teeth of the sun gear is 16 and the number of teeth of the ring gear is 64, during the coasting mode, since the sun gear 101 or the electric motor 12 should be stationary, for the sun gear rotation speed "Ts" to be equal to 0, when the ring rotation speed "Tr" is 200 RPM, the planetary carrier rotation speed "Tc" is 160 RPM.

[0108] According to Configuration "C", during the braking mode, since the friction brake 114 that operates during the braking mode is connected to the planetary carrier 122, the planetary carrier 122 is restricted by the friction brake 114. Therefore, the ring gear 105 rotates the planetary gear 102, and the planetary gear 102 can rotate the sun gear 101 in a direction opposite to the ring rotation direction according to Equation (3), without violating the restriction Tc≧Ts imposed by the one-way bearing 103. By rotating the sun gear 101 with mechanical force instead of electric power, it becomes possible for the vehicle to regenerate energy during the braking mode. For example, assuming that the speed of the ring is equal to 200 RPM (e.g., during coasting) and the speed of the planetary carrier "Tc" is equal to 16 RPM, according to Equation (3), the speed of the motor "Ts" should be equal to -720 RPM, which is a speed of 720 RPM in a direction opposite to the direction in which the ring rotates.

[0109] According to Configuration "C", there may be a low gear mode. During the low gear mode, the brake is fully engaged, thereby locking the planetary carrier 122 and restricting the rotation of the planetary carrier 122. The electric motor 12 can supply power in the reverse direction, i.e., in the direction opposite to the forward driving direction of the ring 105. The planetary gear (gear) 102 is rotated by the sun gear 101, and the planetary gear (gear) 122 may rotate the ring 105 in the direction opposite to the rotation direction of the sun gear, i.e., in the forward driving direction, according to Equation (3) at a ratio determined by the planetary gear (gear) characteristics. For example, when the ring rotation speed "Tr" is equal to 200 RPM and the planetary carrier rotation speed "Tc" is equal to 0, according to Equation (3), the rotation speed of the sun gear or the rotation speed of the electric motor "Ts" is equal to -800 RPM, without violating the limit of Tc≧Ts.

[0110] According to some embodiments, Configuration "D" of Table 800 shows a transmission system implementing a half regenerative differential gear as shown in FIG. 7D. According to Configuration "D", the component of the transmission system connected to the electric motor 12 is the first side gear 611, and its speed is represented by "T1". The component connected to the final drive is the rack carrier 622, and its speed is represented by "Trc". In Configuration "D", a one-way bearing 603 is connected to the rack carrier 622. That is, according to Configuration "D", the rack carrier 622 is allowed to rotate only in one direction with respect to the first side gear 611, for example, via the one-way bearing 103, thereby complying with the condition of Trc≧T1. In Configuration "D", the component connected to the mechanical braking system 114 is the second side gear 604. Therefore, the speed of the second side gear 604 can be reduced to zero (T2→0) in order to generate the rotation of the electric motor 12 via the first side gear 611 and for the energy regeneration by the electric motor 12, and in this case, at least half of the kinetic energy can be dissipated via the mechanical brake so that Regen is defined to be greater than zero and less than 0.5.

[0111] The control parameters of Configuration "D" that can be implemented by the braking mode control algorithm 400 and Equation (4) can be Gear = 2, 0 < Regen < 0.5.

[0112] According to Configuration "D", during the driving mode, the electric motor 12 may be operated to supply power to the rotation of the first side gear 611. The rotation of the first side gear 611 can be forced to rotate the rack carrier 622 along the allowed direction at a ratio of 1:1 through the one-way bearing 603 to which the rack carrier 622 is connected. The rotation of the rack carrier 622 causes the rotation of the final drive, thereby enabling the movement of the vehicle in which the transmission gear of Configuration "D" is internally mounted. For example, when the rotation speed of the first side gear "T1" is equal to 1, the number of turns of the rack carrier "Trc" is also equal to 1 according to the ratio of 1:1, and according to Equation (4), the number of turns of the second side gear "T2" is equal to 1.

[0113] According to Configuration "D", during the coasting mode, the rack carrier 622 rotates freely, whereby the second side gear 604 rotates according to Equation (4), and thereby the first side gear 611 can be stationary. For example, the rotation speed of the rack carrier may be the same as that in the driving mode, for example, Trc = 1. Then, the rotation speed of the second side gear "T2" is made equal to 2 so that the rotation speed of the first side gear "T1" becomes equal to 0, that is, the first side gear is in a stationary state according to Equation (4).

[0114] According to Configuration "D", during the braking mode, the rotation of the second side gear 604 is restricted by the friction brake 614 (and in some cases by the caliper 624). Since the one-way bearing enforces the state of Trc ≧ T1, as is clear from Equation (4), Trc ≦ T2. That is, in the forward driving state, braking and stopping the second side gear "T2" will also stop the rack carrier "Trc", and the best energy regeneration ratio is achieved when T1 = T2.

[0115] Therefore, since the friction brake cannot rotate slower than the electric motor 12, at least 50% of the energy indicated by Regen < 0.5 will be dissipated. However, on the other hand, the mechanical brake can decelerate the vehicle implementing the transmission system of Configuration "D" until it comes to a complete stop.

[0116] According to any configuration of the transmission system of the present disclosure, it should be noted that the user can release the brake at any time just by releasing the brake handle or brake pedal, so that work can be performed under a loaded state.

[0117] According to some embodiments, no electrical energy is required for the application of the friction braking system. The braking torque can be applied by the user via the brake handle or brake pedal at a level similar to that of the current braking system.

[0118] Regarding the flowcharts referred to in this specification, it should be understood that the division of the illustrated method into individual operations represented by the blocks of the flowchart is selected only for convenience and clarity. Alternative divisions that divide the illustrated method into discrete operations are possible with equivalent results. Such alternative divisions that divide the illustrated method into discrete operations should be understood to represent other embodiments of the illustrated method.

[0119] Similarly, it should be understood that, unless otherwise indicated, the illustrated execution order of the operations represented by the blocks of the flowcharts referred to in this specification is selected only for convenience and clarity. The operations of the illustrated method may be executed in an alternative order or simultaneously, with equivalent results obtained. Such reordering of the operations of the illustrated method should be understood to represent other embodiments of the illustrated method.

[0120] Different embodiments are disclosed herein. The features of a particular embodiment can be combined with the features of other embodiments, and thus a particular embodiment may be a combination of the features of multiple embodiments. The foregoing description of embodiments of the present disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure to the precise form disclosed. It should be understood by those skilled in the art that many modifications, variations, substitutions, alterations, and equivalents are possible in light of the above teachings. Accordingly, it is to be understood that the appended claims are intended to cover all modifications and changes that fall within the true spirit of the present disclosure.

[0121] In this specification, certain features of the present disclosure have been illustrated and described, but many modifications, substitutions, alterations, and equivalents will occur to those skilled in the art hereafter. Accordingly, it is to be understood that the appended claims are intended to cover all modifications and changes that fall within the true spirit of the present disclosure.

Claims

1. A power train of a vehicle, an electric motor, a final drive, a two-degree-of-freedom gear system including at least three components configured to rotate one with respect to the other, the gear system being configured to transmit power from the electric motor to the final drive, a mechanical friction brake connected to the gear system via one of the at least three components, the mechanical friction brake being configured to reduce the two degrees of freedom by restricting the rotation of the component to which the mechanical friction brake is connected during the braking mode of the power train, causing the movement of the electric motor, and thereby regenerating the energy by the electric motor, the gear system is a one-way mechanism connected to one of at least three rotating components of the gear system, the one-way mechanism being configured to reduce the two degrees of freedom by restricting the rotation of the one component along a first direction during the power running mode of the power train, the one-way mechanism being configured to allow free rotation of the one component along a second opposite direction during the coasting mode of the power train, and the resistance of the electric motor being avoided, A power train of a vehicle.

2. The power train according to claim 1, wherein the mechanical friction brake is connected to the gear system and not connected to the final drive.

3. The one-way mechanism is an overrunning clutch, The power train according to claim 1.

4. The gear system includes a planetary gear, the at least three components include a sun gear rotatably connected to the electric motor and at least one planetary gear, The at least one planetary gear is rotatably connected to a planetary carrier. The power train according to claim 1.

5. The one-way mechanism is a one-way bearing incorporated as part of the planetary carrier, and the one-way bearing is configured to allow rotation of the planetary carrier in a first direction and to prevent rotation of the planetary carrier in a second direction, the second direction being opposite to the first direction. The power train according to claim 4.

6. The mechanical friction brake is connected to the planetary carrier. The mechanical friction brake is configured to decelerate the rotation of the planetary carrier and to mechanically force the rotation of the electric motor through forced rotation of the sun gear, enabling regenerative braking. The power train according to claim 5.

7. The mechanical friction brake includes a disk brake. The power train according to claim 4.

8. The gear system includes a differential gear system. The at least three components include the electric motor and a first side gear rotatably connected to a horizontal planetary gear, the horizontal planetary gear being rotatably connected to a rack carrier, and the horizontal planetary gear being further rotatably connected to a second side gear. The power train according to claim 1.

9. The one-way mechanism is a one-way bearing incorporated as part of the second side gear, and the one-way bearing is configured to permit rotation of the second side gear in a first direction and to prevent rotation of the second side gear in a second direction, the second direction being opposite to the first direction. The power train according to claim 8.

10. The mechanical friction brake includes a disk brake connected to the second side gear, and the disk brake is configured to mechanically force the rotation of the electric motor through the forced rotation of the first side gear by decelerating the rotation of the second side gear, enabling regenerative braking. The power train according to claim 8.

11. An electric motor, A final drive, A two-degree-of-freedom gear system including at least three components configured to rotate one with respect to the other, the gear system being configured to transmit power from the electric motor to the final drive. The gear system includes a one-way mechanism connected to one of at least three rotating components of the gear system. A mechanical friction brake connected to the gear system through one of the at least three components, the mechanical friction brake being configured to reduce the two degrees of freedom by restricting the rotation of the component to which the mechanical friction brake is connected during the braking mode of the power train, causing the movement of the electric motor, and regenerating the energy by the electric motor. A control system configured to control the amount of power supplied by the electric motor during the driving mode and to control the amount of negative torque applied by the electric motor during the regenerative braking mode. The one-way mechanism is configured to reduce the degrees of freedom of the two degrees of freedom by restricting the rotation of the one component along a first direction during the power running mode of the power train. The one-way mechanism is configured to allow free rotation of the one component along a second opposite direction during the coasting mode of the power train, thereby avoiding the drag of the electric motor. The control system, Detects the braking mode, (i) Define a setpoint value in advance based on the gear ratio of the vehicle and (ii) a parameter that can be changed according to the required regeneration ratio. Calculate a process value based on the ratio between the motor speed and the speed of the final drive. A processor configured to determine a negative torque applied by the electric motor during the regenerative braking mode, the amount of negative torque required for equivalence between the process value and the setpoint value. A vehicle gear system.

12. The required regeneration ratio is determined by at least one of the state of charge (SOC) of the battery / capacitor, power rating, running speed, motor load, terrain, temperature, or a combination thereof. The vehicle gear system according to claim 11.

13. A method for controlling the braking mode of a vehicle, the vehicle comprising an electric motor, a final drive, and a two-degree-of-freedom gear system including at least three components configured to rotate one with respect to the other. The gear system is configured to transmit power from the electric motor to the final drive. The gear system includes a one-way mechanism connected to one of at least three rotating components of the gear system. A mechanical friction brake connected to the gear system via one of the at least three components. The one-way mechanism is configured to reduce the two degrees of freedom of the two-degree-of-freedom by restricting the rotation of the one component along a first direction during the power running mode of the powertrain, while the one-way mechanism is configured to allow the one component to rotate freely along a second opposite direction during the coasting mode of the powertrain, thereby avoiding the drag of the electric motor. The mechanical friction brake is configured to reduce the two degrees of freedom by restricting the rotation of the components to which the mechanical friction brake is connected during the braking mode of the power train, causing the movement of the electric motor, and thereby regenerating energy by the electric motor and the processor. The method includes: detecting a braking mode; predefining a setpoint value based on a parameter that can be changed according to (i) the gear ratio of the vehicle and (ii) the required regeneration ratio; calculating a process value based on the ratio between the motor speed and the speed of the final drive; determining, during the regenerative braking mode, the amount of negative torque applied by the electric motor, which is required for the equivalence between the process value and the setpoint value. A method.

14. Detecting a braking mode further includes determining the motor rotation and determining that the throttle is not applied by the user. The method according to claim 13.

15. The step of calculating the process value includes detecting the motor speed via respective speed sensors and detecting the final drive speed. The method according to claim 13.

16. The method further includes calculating an error indicating the difference between the process value and the setpoint value. The method according to claim 13.

17. The required regeneration ratio is determined by at least one of the state of charge (SOC) of the battery / capacitor, the power ratio, the driving speed, the motor load, the terrain, the temperature, or a combination thereof. The method according to claim 13.

Images