POWER TRANSMISSION UNIT

• US 20100173746A1
• Filed: 06/18/2008
• Published: 07/08/2010
• Est. Priority Date: 06/19/2007
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Ohta, Takashi, Komada, Hideaki, Ideshio, Yukihiko
• Granted Patent: US 8,771,139 B2
• Time in Patent Office: Days
• US Class Current: 477/36
• CPC Class Codes: B60K 2006/541 without reverse ratio using instead electric reversing
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/40 characterised by the assembly or relative disposition of components
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2220/14 Synchronous machines
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/425 Temperature
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 2240/525 Temperature of converter or components thereof
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2260/26 Transition between different drive modes
• CPC Class Codes: B60L 2270/145 Structure borne vibrations
• CPC Class Codes: B60L 3/003 relating to inverters
• CPC Class Codes: B60L 3/0046 : relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/0061 : relating to electrical machines
• CPC Class Codes: B60L 50/16 : with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 7/14 : for vehicles propelled by ac motors
• CPC Class Codes: B60W 10/02 : including control of driveline clutches
• CPC Class Codes: B60W 10/11 : Stepped gearings
• CPC Class Codes: B60W 20/00 : Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/30 : Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: F16H 2003/0818 : comprising means for power-shifting
• CPC Class Codes: F16H 2003/0931 : each countershaft having an output gear meshing with a single common gear on the output shaft
• CPC Class Codes: F16H 2200/0043 : the gear ratios comprising four forward speeds
• CPC Class Codes: F16H 2200/0047 : the gear ratios comprising five forward speeds
• CPC Class Codes: F16H 2200/0052 : the gear ratios comprising six forward speeds
• CPC Class Codes: F16H 3/006 : power being selectively transmitted by either one of the parallel flow paths
• CPC Class Codes: F16H 3/126 : using an electric drive
• CPC Class Codes: F16H 3/725 : with means to change ratio in the mechanical gearing
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

A power transmission unit, which includes: an engine; a plurality of speed change gear pairs, each of which has a different gear ratio, and to which a power outputted from the engine is transmitted; an output member outputting the power transmitted from any of the selected speed change gear pair; a differential mechanism, which has three rotary elements to perform a differential action, and in which a first rotary element of the three rotary elements is connected with the engine; and an electric motor, connected with a second rotary element of the three rotary elements; and wherein the plurality of speed change gear pairs include a first gear pair adapted to be connected with the first rotary element and the output member, and a second gear pair adapted to be connected with a third rotary element of the three rotary elements and the output member. The power transmission unit can reduce a power loss, and is downsized to be mounted on a vehicle easily.

Claims

1. A power transmission unit, which has:

an engine;

a plurality of speed change gear pairs, each of which has a different gear ratio, and to which a power outputted from the engine is transmitted; and

an output member for outputting the power transmitted from the speed change gear pair;

comprising;

a differential mechanism, which has three rotary elements to perform a differential action, and in which a first rotary element of the three rotary elements is connected with the engine; and

an electric motor, which is connected with a second rotary element of the three rotary elements; and

wherein the plurality of speed change gear pairs include a first gear pair which is adapted to be connected with the first rotary element and the output member, and a second gear pair which is adapted to be connected with a third rotary element of the three rotary elements and the output member.

2. The power transmission unit as claimed in claim 1, further comprising:

a locking mechanism for connecting the rotary elements with each other thereby rotating the differential mechanism integrally.

3. The power transmission unit as claimed in claim 2, wherein:

the locking mechanism includes a clutch mechanism, which is adapted to unlock the differential mechanism by disconnecting the connected rotary elements in case of outputting the power to the output member through any of the speed change gear pairs, and to lock the differential mechanism by connecting the rotary elements with each other in case of outputting the power to the output member through another speed change gear pair having a gear ratio for setting a gear stage adjacent to the gear stage set by said any of the speed change gear pair.

4. The power transmission unit as claimed in claim 1, further comprising:

a starting means, which connects the second gear pair with the third rotary element and the output member when the power is outputted to the output member to start the vehicle while allowing the differential mechanism to perform differential action, and then prevents the differential mechanism from performing differential action.

5. The power transmission unit as claimed claim 1, further comprising:

a motoring/regenerating means, which connects any one of the speed change gear pairs with the output member and any one of the rotary elements, which activates the electric motor, and which prevents the differential mechanism from performing differential action, under the condition where the engine is not driven.

6. The power transmission unit as claimed in claim 1, further comprising:

a motoring/regenerating means, which connects the second gear pair with the output member and the third rotary element, which activate the electric motor, and which unlocks the differential mechanism thereby allowing the differential mechanism to perform differential action, under the condition where the engine is not driven.

7. The power transmission unit as claimed in claim 6, wherein:

the motoring/regenerating means includes a means for unlocking the differential mechanism in case the rotational speed of the electric motor is higher than that of the engine, and a torque of the electric motor is balanced with a friction torque of the engine.

8. The power transmission unit as claimed in of claim 1, wherein:

the output member includes two output shafts arranged parallel to each other; and

driven gears of the speed change gear pairs are arranged on those output shafts at a distance.

9. The power transmission unit as claimed in claim 8, wherein:

driven gears of every other speed change gear pairs are arranged in order of gear ratios thereof on one of the output shafts; and

driven gears of the remaining speed change gear pairs are arranged on the other output shaft.

10. The power transmission unit as claimed in claim 8, wherein:

a clutch mechanism for connecting the driven gears on the output shaft selectively with the output shaft is arranged on each output shaft; and

one of the clutch mechanisms is arranged on an opposite side of the other clutch mechanism in the axial direction across the driven gears.

11. The power transmission unit as claimed in claim 8, comprising:

six speed change gear pairs for driving the vehicle in the forward direction; and

wherein driven gears of four of said six gear pairs are arranged on one of the output shafts in a manner to be connected therewith selectively; and

wherein driven gears of the remaining two gear pairs are arranged on the other output shaft in a manner to be connected therewith selectively.

12. The power transmission unit as claimed in claim 11, further comprising:

a first clutch mechanism, which allows a gear pair of the largest gear ratio and a gear pair of the smallest gear ratio arranged adjacent to each other on one of the output shafts to transmit the torque selectively to said one of the output shafts;

a second clutch mechanism, which allows a first odd gear pair whose gear ratio is smaller than the largest gear ratio to set a gear stage two stages higher than the gear stage of the largest gear ratio, and a second odd gear pair whose gear ratio is smaller than that of the first odd gear pair to set a gear stage two stages higher than the gear stage set by the first odd gear pair, which are arranged adjacent to each other on the other output shaft, to transmit the torque selectively to said other output shaft; and

a third clutch mechanism, which allows a first even gear pair whose gear ratio is smaller than the largest gear ratio to set a gear stage one stage higher than the gear stage of the largest gear ratio, and a second even gear pair whose gear ratio is smaller than that of the first even gear pair to set a gear stage two stages higher than the gear stage set by the first even gear pair, which are arranged adjacent to each other on said one of the output shafts, to transmit the torque selectively to said one of the output shafts.

13. The power transmission unit as claimed in claim 1, further comprising:

a reverse mechanism which outputs a torque transmitted thereto from the differential mechanism while reversing a direction of the torque to be opposite to that of the torque transmitted to the output member through the speed change gear pair.

14. The power transmission unit as claimed in claim 13, wherein:

the reverse mechanism comprises a shifting mechanism which connects the output member selectively with the third rotary element.

15. The power transmission unit as claimed in claim 1, further comprising:

a disconnecting mechanism which disconnects the engine from the first rotary element of the differential mechanism thereby preventing the torque to be transmitted to the first rotary element.

16. The power transmission unit as claimed in claim 15, wherein the disconnecting mechanism includes a selective engagement mechanism, which is capable of shifting a sleeve thereof among:

a first position, where the engine is disconnected from the first rotary element, and any of the rotary elements of the differential mechanism are connected with each other to lock the differential mechanism;

a second position, where the engine is connected with the first rotary element, and any of the rotary elements of the differential mechanism are connected with each other to lock the differential mechanism; and

a third position, where the engine is connected with the first rotary element, and the rotary elements of the differential mechanism connected with each other are disconnected from each other to unlock the differential mechanism.

17. The power transmission unit as claimed in claim 2, further comprising:

an electric motor locking mechanism which halts a rotation of the electric motor.

18. The power transmission unit as claimed in claim 17, wherein:

the electric motor locking mechanism includes a mechanism, which halts the rotation of the electric motor in case the second gear pair is connected with the third rotary element and the output member.

19. The power transmission unit as claimed in claim 1, further comprising:

an engine locking mechanism which halts a rotation of the engine.

20. The power transmission unit as claimed in claim 19, wherein:

the engine locking mechanism includes a mechanism, which is adapted to halt the rotation of the engine in case the second gear pair is connected with the third rotary element and the output member, and the electric motor is driven.

21. The power transmission unit as claimed in claim 19, wherein the engine locking mechanism includes a mechanism capable of shifting a sleeve thereof selectively among:

a first position, where the rotation of the engine is halted;

a second position, where any of the rotary elements of the differential mechanism are connected with each other to lock the differential mechanism; and

an electric motor locking position, where the rotation of the electric motor is halted.

22. The power transmission unit as claimed in claim 1, wherein:

the differential mechanism includes a planetary gear mechanism comprising a sun gear as an external gear;

a ring gear as an internal gear, which is arranged concentrically with the sun gear; and

a carrier, which holds a pinion gear arranged between the sun gear and the ring gear in a rotatable and revolvable manner;

the carrier is connected with the engine; and

the sun gear is connected with the electric motor.

23. The power transmission unit as claimed in claim 22, wherein:

a first drive shaft connected with the carrier and a second drive shaft connected with the ring gear are arranged concentrically with each other and coaxially with a rotational center of the planetary gear mechanism; and

the drive gears of the speed change dear pairs are arranged on those shafts.