Method of assembling a hybrid transmission

Abstract

The present disclosure relates to methods of assembling a hybrid transmission. A hybrid transmission includes a permanent magnet rotor selectively held from rotation by a one-way clutch. The one-way clutch utilizes a recessed pocket plate having a plurality of pawls that engage with an inner race in response to energization of a magnetic coil. The recessed pocket plate is fixed to a rotor shaft and axially constrains the laminations, thereby eliminating the need for one of the end plates.

Description

Technical Field

[0001] This disclosure relates to the field of hybrid electric vehicles. More specifically, this disclosure relates to a method of assembling a transmission having a motor and a one-way clutch. Background Technology

[0002] Many vehicles operate over a wide speed range (including both forward and reverse motion). However, some types of engines operate efficiently only within a narrow speed range. Therefore, transmissions, which can efficiently transmit power at various gear ratios, are frequently used. When the vehicle is at low speeds, the transmission typically operates at a high gear ratio to multiply engine torque and improve acceleration. At high speeds, operating the transmission at a low gear ratio allows for engine speeds associated with quiet, fuel-efficient cruising.

[0003] To reduce fuel consumption, some vehicles include hybrid powertrains that use energy storage to supplement the power generated by the internal combustion engine. These powertrains allow the vehicle to run for a period of time with the engine off, and then run for the remaining time at a more efficient torque level than the engine. Hybrid powertrains are also able to capture and subsequently use energy that would otherwise be dissipated by the braking system. Summary of the Invention

[0004] A method of assembling a hybrid transmission includes: sliding a laminated plate stack onto a shaft, inserting a magnet into the laminated plate stack, inserting the shaft into a one-way clutch recess plate, and tightening a nut onto the shaft. The method may further include sliding an end cap onto the shaft before sliding the laminated plate stack onto the shaft to axially constrain further sliding of the end cap on the shaft. The laminated plates and the recess plate each have a tab that engages a groove in the shaft to prevent relative rotation. The nut secures the recess plate and the laminated plate stack to the shaft. A plurality of pawls may be inserted into the recess plate. The assembly method includes inserting the recess plate, the shaft, and the laminated plates into a transmission housing such that the pawls are adjacent to the inner race of the one-way clutch. The inner race of the one-way clutch has an electrical coil configured to generate a magnetic field to attract the pawls to engage with the inner race of the one-way clutch. In some embodiments, the recess plate is formed as a single die-cast part. In some other embodiments, the recess plate is formed by laser welding a flat portion to an annular portion. Both the flat portion and the annular portion may have chamfered surfaces adjacent to the weld.

[0005] A hybrid power transmission includes an end plate, a laminated plate, a slotted rotor shaft, a one-way clutch recess plate, and a nut. The laminated plate contains permanent magnets. The slotted rotor shaft extends through the laminated plate and the end plate, and axially constrains the end plate. Both the laminated plate and the recess plate have tabs that engage slots in the shaft to prevent relative rotation. The nut secures the recess plate and the laminated plate axially against the end plate. The hybrid power transmission may further include a transmission housing, a plurality of pawls, and a one-way clutch inner ring. The plurality of pawls are held within the recess plate. The one-way clutch inner ring is adjacent to the recess plate. The inner ring includes an electric coil configured to generate a magnetic field to attract the pawls to engage with the inner ring. The hybrid power transmission may further include a simple planetary gear set and a second rotor. The simple planetary gear set includes a central gear fixed to the rotor shaft, a ring gear drivably connected to an output shaft, and a gear carrier fixed to an input shaft. The second rotor is drivably connected to the output shaft.

[0006] A one-way clutch cavity plate includes a flat portion, an annular portion, and a plurality of pawls. The flat portion defines a bore and defines at least one tongue extending into the bore. The at least one tongue is configured to engage a slot in a rotor shaft to prevent relative rotation. The annular portion is rigidly fixed to the flat portion and concentric with the bore. The annular portion defines a plurality of cavities that hold the plurality of pawls. The plurality of cavities may be formed on the radially inner surface of the annular portion. Attached Figure Description

[0007] Figure 1 This is a schematic diagram showing the powertrain system of a hybrid vehicle.

[0008] Figure 2 yes Figure 1 A schematic diagram of the cross-section of the optional one-way clutch and generator rotor of the power transmission system.

[0009] Figure 3 yes Figure 2 A diagram of the generator rotor.

[0010] Figure 4 yes Figure 2 A diagram showing the concave plate of the optional one-way clutch.

[0011] Figure 5 It is applicable Figure 1 A diagram of the one-way clutch cavity plate of the power transmission system.

[0012] Figure 6 It is attached to the permanent magnet rotor. Figure 5 A diagram of the cavity plate of a one-way clutch.

[0013] Figure 7 It is attached to the permanent magnet rotor. Figure 5 A cross-sectional view of the one-way clutch cavity plate.

[0014] Figure 8 yes Figure 4 A side view of an alternative embodiment of the concave cavity plate.

[0015] Figure 9 It is assembly Figure 1 The flowchart of the power transmission system process. Detailed Implementation

[0016] Detailed embodiments of the invention are disclosed herein as needed; however, it should be understood that the disclosed embodiments are merely examples of the invention, which may take various forms and alternative forms. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to utilize the invention in various forms.

[0017] Figure 1 A power-split hybrid powertrain is schematically illustrated. Solid lines indicate mechanical power flow connections. Thick dashed lines indicate electrical connections. Thin dashed lines indicate information signal flows. The main drive power is provided by an internal combustion engine 10 driving the input shaft 12. The input shaft 12 is fixedly connected to a planetary carrier 14. A plurality of planetary gears 16 are supported for rotation relative to the planetary carrier 14. Each planetary gear meshes with external teeth on a central gear 18 and with internal teeth on a ring gear 20. The ring gear 20 is fixedly connected to an output shaft 22, which drives the vehicle wheels (not shown).

[0018] The rotor 24 of the first motor is fixedly connected to the output shaft 22. In an alternative embodiment, the rotor 24 may be drivably connected to the output shaft 22 via a mechanical power flow path. The center gear 18 is fixedly connected to the generator shaft 26. The rotor 28 of the second motor is fixedly connected to the generator shaft 26. Both the first and second motors are reversible motors capable of converting electrical power into mechanical power and also capable of converting mechanical power into electrical power. For convenience, the first motor is referred to as a traction motor, and the second motor as a generator. The generator shaft 26 is also selectively kept non-rotating in one direction by an optional one-way clutch (SOWC) 30. The SOWC 30 is a two-state device. In the disengaged state, the SOWC does not restrict the rotation of the generator shaft 26 in any direction. In the engaged state, the SOWC restricts the generator shaft 26 to rotate in the opposite direction of the engine rotation but allows rotation in the direction of engine rotation.

[0019] Controller 32 sends signals to control various components of the powertrain. These signals are based on inputs from several sensors, including a shift lever position sensor 34, a brake pedal position sensor 36, and an accelerator pedal position sensor 38. Controller 32 sends commands to engine 10 to start and stop the engine and to regulate the torque level generated during engine operation. Controller 32 sends commands to SOWC 30 to switch between engaged and disengaged states. Controller 32 regulates the torque generated by the motor by sending commands to inverters 40 and 42. Inverters 40 and 42 regulate the alternating current in the windings of stators 44 and 46, respectively, to generate the commanded torque on the corresponding rotors 28 and 24. When torque is applied in the opposite direction of rotor rotation, the inverters generate direct current (DC) power, which is supplied to DC bus 48. Conversely, when torque is applied in the same direction as rotor rotation, the inverters draw power from DC bus 48. Any net surplus of electrical energy is stored in battery 50 for later use when net shortage occurs.

[0020] When the vehicle is propelled at low speeds using engine power, the planetary gear set divides the power from the engine into a mechanical power flow path and an electrical power flow path. During the low to medium speed range of the ring gear 20, the center gear 18 rotates in the same direction as the planet carrier 14. To provide reaction torque, the generator is operated to generate torque in the opposite direction. The mechanical power flow path transmits power from the planet carrier 14 to the ring gear 20 and then to the output shaft. When the center gear rotates forward, the generator generates electrical power. This electrical power is transmitted from the generator to the DC bus and then to the motor via the electrical power flow path, where the motor converts the power back into mechanical power at the output shaft. When the vehicle speed is higher than the engine speed, the center gear 18 rotates in the opposite direction. In this condition, power circulates within the powertrain. More power is transmitted through the mechanical power flow path than is transmitted to the output shaft. Some mechanical power is extracted by the traction motor and transmitted to the generator, allowing the generator to provide torque reaction.

[0021] Recirculating power flow is generally less efficient than direct power flow. To avoid using recirculating power flow, SOWC 30 can be commanded into engagement mode. In this mode, SOWC provides torque reaction at the center gear 18. Therefore, the power flowing through the electrical power flow path is equal to the power transmitted at the output shaft.

[0022] Figure 2 yes Figure 1A cross-sectional schematic diagram of a portion of the powertrain system shows the structure of the SOWC 30. A one-way clutch recess plate 52 is fixed to the generator rotor 28. Multiple pawls 54 are supported within the recess plate 52 at positions surrounding its inner periphery. The recess plate is the outer ring of the SOWC 30. The inner ring 56 of the SOWC 30 is fixed to the transmission housing to keep it stationary. The outer periphery 58 of the inner ring includes teeth. In the disengaged state, the pawls 54 are kept disengaged from the teeth by springs or other means. In the engaged state, current is supplied to the circumferential winding 60 in the inner ring to establish a magnetic field. The magnetic force pulls the pawls 54 toward the teeth and engages them. The teeth are angled so that the recess plate can rotate relative to the inner ring in one direction in the engaged state. However, the pawls and teeth engage to prevent rotation in the other direction.

[0023] Figure 3 A permanent magnet motor is shown. One or more steel laminations 62 are fixed to a rotor shaft 26. Permanent magnets are inserted within the steel laminations to generate alternating magnetic poles around the circumference. Steel is used because it is magnetically conductive. Aluminum end plates are mounted at each end of the steel laminations. The end plates are made of aluminum because it is not magnetically conductive. Therefore, the end plates confine the magnetic field to the circumference of the rotor, where the magnetic field interacts with the stator. Figure 3 One end plate, not visible in the middle, is axially held against a shoulder in the shaft 26. The other end plate 64 is axially held by a nut 66, which is screwed onto the threaded portion of the shaft 26.

[0024] Figure 4 A one-way clutch recess plate 52 is shown. Recess plate 52 and end plate 64 include features for attaching the recess plate to the rotor. A pin is inserted into a hole 70 in the end plate and fitted into a hole 72 in the recess plate to precisely position the recess plate relative to the end plate. A bolt is then inserted through a hole 68 in the recess plate and into a threaded hole 74 in the end plate. The pin and bolt must be made of a non-magnetic material (such as stainless steel) to avoid altering the magnetic flux path within the rotor. These bolts are relatively expensive due to their low production volume. Furthermore, the thickness of the end plate provides limited thread engagement.

[0025] Figure 5 An aluminum cavity plate 76 is shown. The cavity plate 76 can be formed as a single piece using, for example, a die-casting process. Some machining may be required. The cavity plate 76 includes a flat portion 78 with a central hole. Two protruding tongues 80 extend into the hole. The cavity plate also includes a thickened annular portion 82, which is axially close to the flat portion and concentric with the hole. A plurality of pawls 54 are inserted into a cavity formed around the inner periphery of the annular portion. Figure 6 and Figure 7A permanent magnet rotor including a recessed plate 76 is shown. When the recessed plate 76 is inserted onto the shaft 26, a tongue 80 fits into a slot in the shaft 26. A nut 66 is screwed onto the shaft 26 and tightened to hold the recessed plate against the laminated stack 62. No end plate is required at one end of the rotor. No pins or bolts are needed, thus avoiding any tendency to disrupt the magnetic flux path.

[0026] Figure 8 An alternative method for manufacturing the cavity plate 76 is shown. In this alternative, the flat portion 78 and the annular portion 82 are manufactured separately and then joined together by a laser welding section 84. To facilitate uniform weld penetration into each component, the flat portion 78 includes a chamfered surface 86, and the annular portion 82 includes a chamfered surface 88.

[0027] Figure 9 The process of assembling a hybrid transmission is illustrated. At 90, a permanent magnet is inserted into a stack of laminations made of steel or some other magnetically conductive material. At 92, an end plate is inserted into the shaft. The end plate is axially restrained by a shoulder formed into the shaft. At 94, at least one stack of laminations is inserted into the shaft. The laminations include tabs that are fitted into axial slots in the shaft to prevent relative rotation. At 96, a cavity plate is inserted into the shaft. The cavity plate also includes tabs fitted into slots in the shaft. At 98, a nut is tightened into the threaded portion of the shaft. At 100, a set of pawls is inserted into a set of cavities formed in the cavity plate. At 102, the inner ring of a one-way clutch is inserted into the transmission housing. The inner ring includes a coil. At 104, the cavity plate, shaft, and laminations are inserted into the transmission housing, with the pawls close to the inner ring, such that the coil generates a magnetic field to attract the pawls to engage with the inner ring.

[0028] While exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms of the invention. Rather, the terms used in this specification are descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of the invention. Furthermore, features of various implementations may be combined to form further embodiments of the invention.

Claims

1. A method for assembling a hybrid power transmission, comprising: The end plate is slidably mounted onto the rotor shaft to axially constrain the sliding of the end plate on the rotor shaft; The laminated stack is slidably mounted onto the rotor shaft; Permanent magnets are inserted into the lamination stack to form a rotor assembly; The rotor shaft is inserted into the one-way clutch cavity plate. The stacked plates and the one-way clutch cavity plate each have a tongue that engages with a groove in the rotor shaft to prevent relative rotation. The one-way clutch cavity plate and the end plate are respectively disposed on both sides of the stacked plates in the axial direction. The one-way clutch cavity plate has an annular portion formed around its circumferential direction and extending away from the stacked plates. The inner periphery of the annular portion is formed with a plurality of cavities spaced apart around the circumferential direction. Tighten the nut onto the rotor shaft to fix the one-way clutch cavity plate and the stack of plates axially against the end plate; Multiple pawls are inserted into the multiple cavities of the one-way clutch cavity plate.

2. The method according to claim 1, further comprising: The one-way clutch cavity plate, rotor shaft, and laminations are inserted into the transmission housing such that the pawl is adjacent to the one-way clutch inner ring, which has an electric coil configured to generate a magnetic field to attract the pawl to engage with the one-way clutch inner ring.

3. The method according to claim 1, wherein, The one-way clutch cavity plate is formed as a single die-cast part.

4. The method according to claim 1, further comprising: The one-way clutch cavity plate is formed by laser welding the flat portion to the annular portion.

5. The method according to claim 4, wherein, Both the flat portion and the annular portion have chamfered surfaces adjacent to the welded portion.

6. A hybrid power transmission, comprising: A first rotor includes: an end plate; a laminated stack containing permanent magnets; and a slotted rotor shaft extending through the laminated stack and the end plate, and axially constraining the end plate. A one-way clutch cavity plate and an end plate are respectively disposed on both sides of the laminate stack. Both the laminate and the one-way clutch cavity plate have a tongue that engages a slot in the rotor shaft to prevent relative rotation. The one-way clutch cavity plate has an annular portion formed around its circumferential direction and extending away from the laminate stack. The inner periphery of the annular portion is formed with a plurality of cavities spaced apart around the circumferential direction. Nuts are used to fix the one-way clutch cavity plate and the stack of discs axially against the end plate; Multiple pawls are respectively held within the multiple cavities of the one-way clutch cavity plate.

7. The hybrid transmission according to claim 6, further comprising: Transmission housing; A one-way clutch inner ring, near a one-way clutch cavity plate, includes an electric coil configured to generate a magnetic field to attract a pawl to engage with the one-way clutch inner ring.

8. The hybrid transmission according to claim 7, further comprising: A simple planetary gear set having a central gear fixed to the rotor shaft, a ring gear drivably connected to the output shaft, and a gear carrier fixed to the input shaft; The second rotor is drivably connected to the output shaft.

9. A one-way clutch cavity plate, wherein, The one-way clutch cavity plate is for attachment to the rotor and includes: The flat end plate portion abuts against the stack of rotor laminations and defines a hole and at least one tongue extending into the hole, the at least one tongue being configured to engage a slot of the rotor shaft of the rotor to prevent relative rotation. The annular clutch portion surrounds and is rigidly fixed to the flat end plate portion and concentric with the hole, and defines a plurality of recesses. The plurality of cavities are respectively used to hold the plurality of pawls inside them, such that each of the plurality of pawls is adjacent to the inner ring of the one-way clutch.

10. The concave cavity plate according to claim 9, wherein, The plurality of cavities are formed on the radial inner surface of the annular clutch portion.

Images