1. A powertrain for a vehicle, the powertrain comprising:

a first input shaft selectively connectable to an engine through a first clutch;

a second input shaft selectively connectable to an engine through a second clutch and mounted coaxially with the first input shaft;

a motor input shaft mounted coaxially with the first input shaft and to which a motor is connected;

a first output shaft and a second output shaft, each of the first output shaft and the second output shaft being mounted parallel to the first input shaft and the second input shaft;

a central synchronization unit installed between the first input shaft and the motor input shaft and configured to interrupt a connection between the first input shaft and the motor input shaft;

a plurality of gears installed between the motor input shaft and the first output shaft, between the first input shaft and the second output shaft, between the second input shaft and the first output shaft, and between the second input shaft and the second output shaft, and configured to form a series of gear ratios for vehicle travel; and

a variable transmission mechanism configured to continuously change power of the motor input shaft by using the central synchronizing unit and to transmit the changed power to the first output shaft.

2. The powertrain for a vehicle according to claim 1, wherein the variable transmission mechanism includes:

a variable drive gear rotatably mounted to the motor input shaft;

a variable driven gear fixedly connected to a first output shaft and engaged with the variable driving gear; and

a servo clutch configured to continuously change a frictional force between the motor input shaft and the variable driving gear by an operation of the central synchronizing unit.

3. The powertrain for a vehicle according to claim 2,

the servo clutch is a conical friction clutch;

the tapered surface of the servo clutch is integrally formed with the variable drive gear.

4. The powertrain for a vehicle according to claim 3, wherein the central synchronization unit includes:

a central hub mounted to the motor input shaft;

a central sleeve mounted to slide over the central hub in an axial direction of the central sleeve; and

a synchronizer connected to the first input shaft by synchronization by a synchronizer ring when the center sleeve moves in the first direction;

wherein the central sleeve is configured to: the tapered surface of the variable drive gear is pressed when the center sleeve moves in the second direction.

5. The powertrain for a vehicle of claim 4, wherein the plurality of gears includes a first gear set, a second gear set, a third gear set, a fourth gear set, and a fifth gear set,

wherein:

a first gear set between the motor input shaft and the first output shaft is respectively used for a first gear transmission ratio and a second gear transmission ratio;

a second gear set between the first input shaft and the first output shaft is used for a fourth gear transmission ratio;

a third gear set between the first input shaft and the second output shaft is used for a sixth gear transmission ratio;

a fourth gear set between the second input shaft and the first output shaft is used for a fifth gear transmission ratio;

a fifth gear set between the second input shaft and the second output shaft is used for a third gear ratio.

6. The powertrain for a vehicle according to claim 5,

the first gear set comprises a first driving gear and a second driving gear, and the first driving gear for the first gear transmission ratio and the second driving gear for the second gear transmission ratio are arranged on the motor input shaft;

a first driven gear meshed with the first driving gear and a second driven gear meshed with the second driving gear are arranged on the first output shaft;

the second and third gear sets comprise a third drive gear mounted to the first input shaft and common to a fourth gear transmission ratio and a sixth gear transmission ratio;

the fourth and fifth gear sets include a fourth drive gear mounted to the second input shaft and common to the third and fifth gear ratios;

a fourth driven gear meshed with the third driving gear and a fifth driven gear meshed with the fourth driving gear are arranged on the first output shaft;

a sixth driven gear that meshes with the third drive gear and a third driven gear that meshes with the fourth drive gear are mounted to the second output shaft.

7. The powertrain for a vehicle according to claim 6,

the first driving gear and the second driving gear are fixedly arranged on the motor input shaft, so that the rotation of the first driving gear and the rotation of the second driving gear are restricted by the motor input shaft;

the third driving gear is fixedly arranged on the first input shaft, so that the rotation of the third driving gear is restricted by the first input shaft;

the fourth drive gear is fixedly mounted to the second input shaft such that rotation of the fourth drive gear is constrained by the second input shaft;

first and second synchronizers configured to selectively restrict rotation of the first driven gear and rotation of the second driven gear are mounted to the first output shaft, and fourth and fifth synchronizers configured to selectively restrict rotation of the fourth driven gear and rotation of the fifth driven gear are mounted to the first output shaft;

third and sixth synchronizers configured to selectively restrict rotation of the third driven gear and rotation of the sixth driven gear are mounted to the second output shaft.

8. The powertrain for a vehicle according to claim 7,

a synchronizer configured to perform synchronization by using a synchronizer ring is installed between the first and second synchronizers and the first driven gear;

a dog clutch in which sleeves of the first and second synchronizers are directly engaged with a clutch gear of the second driven gear is installed between the first and second synchronizers and the second driven gear.

9. The powertrain for a vehicle according to claim 8,

the opposed surfaces of the sleeve of the first and second synchronizers and the clutch gear of the second driven gear, which are engaged with each other, have a planar shape perpendicular to the axial direction thereof.

10. The power train for a vehicle according to claim 9, wherein the clutch gear of the second driven gear and the end portions of the sleeve gears of the sleeves of the first and second synchronizers facing the clutch gear of the second driven gear form a planar shape facing each other.

11. The powertrain for a vehicle of claim 7, wherein the first and second synchronizers comprise:

a first clutch gear connected to the first driven gear;

a second clutch gear connected to the second driven gear;

a hub fixed to the first output shaft; and

a sleeve slidably engaged to the hub and configured to selectively restrict rotation of the first driven gear and rotation of the second driven gear in accordance with movement of the sleeves of the first and second synchronizers.

12. The powertrain for a vehicle of claim 7, wherein the fourth and fifth synchronizers comprise:

a first clutch gear connected to the fourth driven gear;

a second clutch gear connected to the fifth driven gear;

a hub fixed to the first output shaft; and

a sleeve slidably engaged to the hub and configured to selectively restrict rotation of the fourth driven gear and rotation of the fifth driven gear in accordance with movement of the sleeves of the fourth and fifth synchronizers.

13. The powertrain for a vehicle of claim 7, wherein the third and sixth synchronizers comprise:

a first clutch gear connected to the third driven gear;

a second clutch gear connected to the sixth driven gear;

a hub fixed to the second output shaft; and

a sleeve slidably engaged to the hub and configured to selectively restrict rotation of the third driven gear and rotation of the sixth driven gear in accordance with movement of the sleeves of the third and sixth synchronizers.

14. The powertrain for a vehicle of claim 6, wherein a gear ratio of the variable driving gear to the variable driven gear is less than a gear ratio of the first driving gear to the first driven gear and a gear ratio of the second driving gear to the second driven gear.

15. The powertrain for a vehicle according to claim 6, wherein a clutch gear that meshes with a central sleeve of the central synchronizing unit is integrally formed with a third drive gear.

16. The powertrain for a vehicle according to claim 1,

the first clutch and the second clutch correspond to a dual clutch formed in one clutch housing;

the second input shaft is a hollow shaft surrounding the first input shaft.

Background

A Transmission Mounted Electric Device (TMED) hybrid powertrain refers to a powertrain in which an electric machine is not mounted on an engine but is mounted on a transmission.

Generally, among the above-mentioned TMED hybrid powertrains, a TMED hybrid powertrain that connects an engine and an electric motor by using an engine clutch has been widely used, but for the powertrain, there is an additional cost in providing the engine clutch, the rotational speeds of the engine and the electric motor must be the same when the engine clutch is coupled, a main operation region is concentrated in a low speed region since a shift map is set according to an optimal operation point of the engine, and thus performance of the electric motor cannot be sufficiently achieved, and a power transmission path from a driving wheel to the electric motor becomes complicated during regenerative braking since the electric motor is located near an input side of a transmission, thereby decreasing regenerative braking efficiency.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

Various aspects of the present invention are directed to provide a hybrid powertrain for a vehicle, which may reduce manufacturing costs and weight of the hybrid powertrain for a vehicle by excluding an engine clutch for interrupting the connection of an engine and an electric machine, enable the electric machine as well as the engine to achieve optimal operation by controlling the electric machine independently of the engine, and may make a power transmission path between the electric machine and driving wheels during regenerative braking shorter, so that efficiency of the hybrid powertrain during EV mode and regenerative braking may be improved.

According to an aspect of the present invention, a hybrid powertrain for a vehicle may include: a first input shaft selectively connectable to an engine through a first clutch; a second input shaft selectively connectable to an engine through a second clutch and mounted coaxially with the first input shaft; a motor input shaft mounted coaxially with the first input shaft and to which a motor is connected; a first output shaft and a second output shaft, each of the first output shaft and the second output shaft being mounted parallel to the first input shaft and the second input shaft; a central synchronization unit installed between the first input shaft and the motor input shaft and configured to interrupt a connection between the first input shaft and the motor input shaft; a plurality of pairs of external gears installed between the motor input shaft and the first output shaft, between the first input shaft and the second output shaft, between the second input shaft and the first output shaft, and between the second input shaft and the second output shaft, and configured to form a series of gear ratios for vehicle travel; and a variable power transmission mechanism configured to continuously change power of the motor input shaft by using the central synchronizing unit and to transmit the changed power to the first output shaft.

The variable transmission mechanism may include: a variable drive gear rotatably mounted to the motor input shaft; a variable driven gear fixedly connected to a first output shaft to mesh with the variable driving gear; and a servo clutch configured to continuously change a frictional force between the motor input shaft and the variable driving gear by an operation of the central synchronizing unit.

The servo clutch may be a tapered friction clutch type, and a tapered surface of the servo clutch may be integrally formed with the variable drive gear.

The central synchronization unit may include: a central hub mounted to the motor input shaft; a central sleeve configured to slide over a central hub in an axial direction of the central sleeve; and a synchronizer may be provided which is connected to the first input shaft by synchronization by the synchronizer ring when the center sleeve is moved to one axial side thereof; and the central sleeve may press the tapered surface of the variable drive gear when the central sleeve moves in the second direction.

The external gear pair between the motor input shaft and the first output shaft can be used for a first gear transmission ratio and a second gear transmission ratio respectively, the external gear pair between the first input shaft and the first output shaft can be used for a fourth gear transmission ratio, the external gear pair between the first input shaft and the second output shaft can be used for a sixth gear transmission ratio, the external gear pair between the second input shaft and the first output shaft can be used for a fifth gear transmission ratio, and the external gear pair between the second input shaft and the second output shaft can be used for a third gear transmission ratio.

A first driving gear for a first gear transmission ratio and a second driving gear for a second gear transmission ratio may be installed at the motor input shaft, a first driven gear engaged with the first driving gear and a second driven gear engaged with the second driving gear may be installed at the first output shaft, a third driving gear commonly used for a fourth gear transmission ratio and a sixth gear transmission ratio may be installed at the first input shaft, a fourth driving gear commonly used for a third gear transmission ratio and a fifth gear transmission ratio may be installed at the second input shaft, a fourth driven gear engaged with the third driving gear and a fifth driven gear engaged with the fourth driving gear may be installed at the first output shaft, and a sixth driven gear engaged with the third driving gear and a third driven gear engaged with the fourth driving gear may be installed at the second output shaft.

The first drive gear and the second drive gear may be mounted to the motor input shaft such that rotation of the first drive gear and rotation of the second drive gear are constrained, the third drive gear may be mounted to the first input shaft, so that the rotation of the third driving gear is restricted, the fourth driving gear is mounted to the second input shaft, so that the rotation of the fourth drive gear may be restricted, first and second synchronizers configured to selectively restrict the rotation of the first driven gear and the rotation of the second driven gear may be provided to the first output shaft, and fourth and fifth synchronizers configured to selectively restrict rotation of the fourth driven gear and rotation of the fifth driven gear may be provided to the first output shaft, and third and sixth synchronizers configured to selectively restrict rotation of the third driven gear and rotation of the sixth driven gear may be provided to the second output shaft.

A synchronizer configured to perform synchronization by using a synchronizer ring may be provided between the first and second synchronizers and the first driven gear, and a dog clutch in which sleeves of the first and second synchronizers are directly engaged with a clutch gear of the second driven gear may be provided between the first and second synchronizers and the second driven gear.

The opposite surfaces of the sleeve of the first and second synchronizers and the clutch gear of the second driven gear, which are engaged with each other, may have a planar shape perpendicular to the axial direction thereof.

The transmission ratio of the variable driving gear to the variable driven gear may be smaller than the transmission ratio of the first driving gear to the first driven gear and the transmission ratio of the second driving gear to the second driven gear.

A clutch gear engaged with the central sleeve of the central synchronizing unit may be integrally formed with the third driving gear.

The first clutch and the second clutch may correspond to a dual clutch formed in one clutch housing, and the second input shaft may be a hollow shaft surrounding the first input shaft.

According to exemplary embodiments of the present invention, manufacturing costs and weight of a hybrid powertrain for a vehicle may be reduced by excluding an engine clutch for interrupting connection of an engine and an electric machine, optimal operation of the electric machine and the engine may be enabled by controlling the electric machine independently of the engine, and a power transmission path between the electric machine and driving wheels during regenerative braking may be made shorter, so that efficiency of the hybrid powertrain during EV mode and regenerative braking may be improved.

The method and apparatus of the present invention have other features and advantages which will be apparent from or are set forth in detail in the accompanying drawings and the following detailed description, which are incorporated herein, and which together serve to explain certain principles of the invention.

Drawings

Fig. 1 is a schematic diagram exemplarily showing a configuration of a hybrid powertrain for a vehicle according to an exemplary embodiment of the present invention;

2A, 2B, 2C, 2D, 2E and 2F are schematic diagrams illustrating a shift from a first gear to a second gear by the powertrain of FIG. 1;

3A, 3B and 3C are schematic diagrams illustrating a shift from second gear to third gear by the powertrain of FIG. 1;

4A, 4B and 4C are schematic diagrams illustrating a shift from third gear to fourth gear by the powertrain of FIG. 1;

5A, 5B, 5C, 5D and 5E are schematic diagrams illustrating a shift from fourth to fifth gear by the powertrain of FIG. 1;

6A, 6B and 6C are schematic diagrams illustrating a shift from fifth to sixth gear by the powertrain of FIG. 1;

7A, 7B, 7C and 7D are schematic diagrams illustrating a shift from a first EV gear to a second EV gear by the powertrain of FIG. 1;

fig. 8 is a sectional view of a main portion of the first synchronizer and the second synchronizer of fig. 1;

fig. 9 is a table for comparing the operations of the first synchronizer and the second synchronizer of fig. 8 with the prior art.

It should be understood that the drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features included in the present invention, including, for example, specific dimensions, orientations, locations, and shapes, will be determined in part by the particular application and environment of use desired.

In the drawings, like or equivalent elements of the invention are designated with reference numerals throughout the several views of the drawings.

Detailed Description

Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with the exemplary embodiments of the invention, it will be understood that this description is not intended to limit the invention to those exemplary embodiments. On the other hand, the present invention is intended to cover not only exemplary embodiments of the present invention, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the present invention as defined by the appended claims.

Referring to fig. 1, an exemplary embodiment of a hybrid powertrain for a vehicle according to an exemplary embodiment of the present invention includes: a first input shaft IN1, a second input shaft IN2, a motor input shaft MI, a first output shaft OUT1 and a second output shaft OUT2, a central synchronizing unit CS, a plurality of pairs of external gears, and a variable transmission mechanism; the first input shaft IN1 is connected to the engine E through a first clutch CL 1; the second input shaft IN2 is connected to the engine E through a second clutch CL2 and is mounted coaxially with the first input shaft IN 1; the motor input shaft MI is installed coaxially with the first input shaft IN1, and the motor M is connected to the motor input shaft MI; the first and second output shafts OUT1 and OUT2 are mounted parallel to the first and second input shafts IN1 and IN 2; the central synchronization unit CS is configured to interrupt the connection of the first input shaft IN1 with the motor input shaft MI; a plurality of pairs of external gears are installed between the motor input shaft MI and the first output shaft OUT1, between the first input shaft IN1 and the first output shaft OUT1, between the first input shaft IN1 and the second output shaft OUT2, between the second input shaft IN2 and the first output shaft OUT1, and between the second input shaft IN2 and the second output shaft OUT2, and are configured to form a series of gear ratios for vehicle travel; the variable transmission mechanism is configured to continuously change the power of the motor input shaft MI by using the central synchronizing unit CS and transmit the changed power to the first output shaft OUT 1.

That is, in the exemplary embodiment of the present invention, the vehicle is configured to achieve a series of gear ratios of the first gear to the sixth gear using a plurality of pairs of external gears by the power transmitted from the engine E or the motor M.

The first clutch CL1 and the second clutch CL2 include a dual clutch DCL formed IN one clutch housing, the second input shaft IN2 is a hollow shaft that surrounds the first input shaft IN1, the first output shaft OUT1 is provided with a first output gear OG1, the second output shaft OUT2 is provided with a second output gear OG2, and the first output gear OG1 and the second output gear OG2 are commonly meshed with the ring gear RG of the differential DF.

That is, according to the power train of the present invention, when the first and second input shafts IN1 and IN2 transmit the power of the engine E, which is received through the first and second clutches CL1 and CL2 of the dual clutch DCL, to the first and second output shafts OUT1 and OUT2, the third to sixth gears can be achieved, when the first input shaft IN1 is connected to the motor input shaft MI and the engine power transmitted to the motor input shaft MI is transmitted to the first output shaft OUT1, the first and second gears can be achieved, the power of the gears achieved as described above can be extracted through the differential DF, and during a shift operation, smooth shifting can be performed without any torque interruption by shifting as described below.

Further, since the motor M is not mounted in the engine E through the engine clutch and thus the engine clutch is not mounted, the manufacturing cost of the vehicle can be reduced and the weight can be reduced, since the motor can be controlled independently of the engine, the degree of freedom of control of the motor M can become higher, and since the power can be transmitted between the motor M and the drive wheels through a relatively short power transmission path in the EV mode or during regenerative braking, the power transmission efficiency can become higher.

The variable transmission mechanism includes: a variable drive gear VD, a variable driven gear VP, and a servo clutch SC; the variable drive gear VD is rotatably mounted to the motor input shaft MI; the variable driven gear VP is mounted to the first output shaft OUT1 to mesh with the variable drive gear VD; the servo clutch SC is configured to continuously change the frictional force between the motor input shaft MI and the variable drive gear VD by the operation of the central synchronizing unit CS.

The servo clutch SC is a tapered friction clutch type, and a tapered surface CN of the servo clutch SC is integrally formed with the variable drive gear VD.

Of course, not only the conical friction clutch but also various friction clutches such as a general flat plate type friction clutch may be used as the servo clutch SC.

The central synchronizing unit comprises a central hub part CHB and a central sleeve CSB, and the central hub part CHB is arranged on the motor input shaft MI; the central sleeve CSB is configured to slide on the central hub CHB along its axial direction; and the central synchronizing unit is provided with a synchronizer which is connected to the first input shaft IN1 by synchronization of the synchronizer when the central sleeve CSB is moved to one axial side thereof, and presses the tapered surface CN of the variable drive gear VD when the central sleeve CSB is moved to the opposite axial side thereof.

Here, the "axial direction" means a longitudinal direction of the motor input shaft MI.

Referring to fig. 1, as shown IN the left side of the central synchronizing unit CS, a third driving gear DG3 is installed while its rotation is restricted by a first input shaft IN1, and a clutch gear 3_ CG that can be engaged with a central sleeve CSB of the central synchronizing unit CS is integrally provided on the third driving gear DG 3.

The synchronizer ring is disposed between the clutch gear 3_ CG of the third drive gear DG3 and the center sleeve CSB, and the center sleeve CSB is meshed with the clutch gear 3_ CG of the third drive gear DG3 by synchronization of the synchromesh-type synchronizer.

For reference, the same type of synchronizer ring as a conventional general synchromesh synchronizer may be utilized, and its illustration is omitted in fig. 1.

Meanwhile, the servo clutch SC is disposed at the right side of the central synchronizing unit CS, and the central sleeve CSB of the central synchronizing unit CS may be configured to attach the tapered friction ring to the tapered surface CN of the variable driving gear VD, and the other tapered surface may be formed at the right inner side of the central sleeve CSB, so that the tapered surface of the central sleeve CSB may be directly attached to the tapered surface CN of the variable driving gear VD.

Further, the capacity of the actuator that drives the center sleeve CSB can be reduced and the frictional force of the servo clutch SC can be sufficiently ensured by providing the operating force increasing mechanism that attaches the friction ring to the tapered surface CN of the variable drive gear VD by increasing the axial operating force of the center sleeve CSB between the center sleeve CSB and the friction ring.

A pair of external gears between the motor input shaft MI and the first output shaft OUT1 are used for the first and second shift ratios, respectively, a pair of external gears between the first input shaft IN1 and the first output shaft OUT1 are used for the fourth shift ratio, a pair of external gears between the first input shaft IN1 and the second output shaft OUT2 are used for the sixth shift ratio, wherein a pair of external gears between the second input shaft IN2 and the first output shaft OUT1 is used for the fifth shift ratio, and a pair of external gears between the second input shaft IN2 and the second output shaft OUT2 is used for the third shift ratio.

That is, the first drive gear DG1 for the first shift ratio and the second drive gear DG2 for the second shift ratio are mounted to the motor input shaft MI, a first driven gear P1 meshing with the first drive gear DG1 and a second driven gear P2 meshing with the second drive gear DG2 are mounted on the first output shaft OUT1, a third drive gear DG3 common to the fourth shift ratio and the sixth shift ratio is mounted on the first input shaft IN1, a fourth drive gear DG4 common to the third shift ratio and the fifth shift ratio is mounted on the second input shaft IN2, a fourth driven gear P4 meshing with the third drive gear DG3 and a fifth driven gear P5 meshing with the fourth drive gear DG4 are mounted on the first output shaft OUT1, a sixth driven gear P6 meshing with the third drive gear DG3 and a third driven gear P3 meshing with the fourth drive gear DG4 are attached to the second output shaft OUT 2.

A first drive gear DG1 and a second drive gear DG2 are mounted on the motor input shaft MI such that rotation thereof is restricted, a third drive gear DG3 is mounted on the first input shaft IN1 such that rotation thereof is restricted, a fourth drive gear DG4 is mounted on the second input shaft IN2 such that rotation thereof is restricted, first and second synchronizers 1&2S configured to selectively restrict rotation of the first driven gear P1 and the second driven gear P2 and fourth and fifth synchronizers 4&5S configured to selectively restrict rotation of the fourth driven gear P4 and the fifth driven gear P5 are provided to the first output shaft, and third and sixth synchronizers 3&6S configured to selectively restrict rotation of the third driven gear P3 and the sixth driven gear P6 are provided to the second output shaft OUT 2.

Here, the third and sixth synchronizers 3&6S and the fourth and fifth synchronizers 4&5S are provided with synchronizer rings on opposite sides of the hub, respectively, and thus, when the sleeve is engaged with the gears located on opposite sides of the hub, they can be smoothly engaged with each other by synchronization.

A synchronizer configured to perform synchronization by using a synchronizer ring is provided between the first and second synchronizers 1&2S and the first driven gear P1, and a dog clutch, in which the sleeve 1&2_ SB of the first and second synchronizers 1&2S is directly engaged with the clutch gear of the second driven gear, is provided between the first and second synchronizers 1&2S and the second driven gear P2.

That is, the first and second synchronizers 1&2S are provided with a synchronizer at a side close to the first driven gear P1, but are provided with a dog clutch at a side close to the second driven gear P2, which does not include a synchronizer ring.

Further, as shown in fig. 8, the opposing surfaces of the sleeve 1&2_ SB of the first and second synchronizers 1&2S and the clutch gear 2_ CG of the second driven gear P2, which are engaged with each other, may have a planar shape perpendicular to the axial direction thereof.

The opposed surfaces of the sleeve 1&2_ SB of the first and second synchronizers 1&2S and the clutch gear 2_ CG of the second driven gear P2 having a planar shape perpendicular to the axial direction thereof means that: as shown in the right side of fig. 8, the clutch gear 2_ CG of the second driven gear P2 and the end of the sleeve gear SG of the sleeves 1&2_ SB facing the clutch gear 2_ CG form a planar shape (X, Y) facing each other.

Fig. 8 is a sectional view taken along a circumferential direction of the hub portions 1&2_ HB around a center line at which the hub portions 1&2_ HB and the sleeves 1&2_ SB of the first and second synchronizers 1&2S are spline-coupled to each other, and a middle portion of fig. 8 shows that the hub portions 1&2_ HB and the sleeve gears SG of the sleeves 1&2_ SB are alternately mounted, the clutch gear 2_ CG of the second driven gear P2 is shown on a right side of fig. 8, and the clutch gear 1_ CG and the synchronizer ring SR of the first driven gear P1 are shown on a left side of fig. 8.

As described above, as shown in the drawings, the synchronizer ring SR is mounted between the first driven gear P1 and the hub portions 1&2_ HB, the clutch gear 1_ CG of the first driven gear P1 has a chamfer inclined axially toward the sleeve gear SG as in the conventional ordinary synchromesh type shift mechanism, and an axially mounted chamfer is also provided in the sleeve gear SG.

Therefore, when shifting is performed by sliding the sleeve 1&2_ SB toward the first driven gear P1 from the neutral state corresponding to the central portion of the hub portion 1&2_ HB, shifting is performed in the same manner as in the conventionally known art.

Meanwhile, the process of performing the shifting operation of engaging the sleeve 1&2_ SB with the second driven gear P2 is different from the conventional art.

First, before the sleeve 1&2_ SB comes into contact with the second driven gear P2, a synchronous operation is performed by engaging the servo clutch SC. That is, since a separate synchronizer ring is not provided as in the conventional art, synchronization is not performed by the synchronizer ring, but a transmission ratio of the variable driving gear VD to the variable driven gear VP (as will be described later) is slightly smaller than that of the second driving gear DG2 to the second driven gear P2, and therefore, a time for synchronization is generated when the servo clutch SC is coupled, and thereafter, a difference in relative rotational speed hardly occurs.

When the synchronization is achieved, the shifting is achieved by pushing the sleeve 1&2_ SB toward the second driven gear P2, and then, the case where the sleeve gear SG and the clutch gear 2_ CG of the second driven gear P2 meet each other corresponds to the two cases shown in the lower side of fig. 9.

That is, two cases correspond to a left case where the sleeve gear SG and the clutch gear 2_ CG meet each other while being precisely staggered with each other to be immediately engaged with each other without being blocked by each other, thereby completing the shifting operation, and a right case where the plane shapes meet each other and collide with each other.

As shown in the drawing, when the planar shape of the sleeve gear SG and the planar shape of the clutch gear 2_ CG meet each other and collide with each other, the RPM of the sleeve gear SG is slightly larger than that of the clutch gear 2_ CG due to a slight difference between gear ratios as described below, and therefore, the sleeve gear SG and the clutch gear 2_ CG meet while being precisely staggered with each other to be precisely meshed with each other as a predetermined period of time passes.

For reference, in order to simply compare the RPM of the clutch gear 2_ CG and the RPM of the sleeve gear SG, fig. 9 shows a difference between the relative rotation speeds of the clutch gear 2_ CG and the sleeve gear SG by representing the RPM ω of the clutch gear 2_ CG as 0RPM and the RPM ω of the sleeve gear SG as 2 RPM.

Meanwhile, the upper side of fig. 9 shows three different cases where the shift operation is performed in a conventional ordinary structure, in which the opposing surfaces of the sleeve gear SG and the clutch gear 2_ CG do not have a planar shape perpendicular to the axial direction thereof, and each of the sleeve gear SG and the clutch gear 2_ CG has a chamfer inclined with respect to the axial direction as in a conventional ordinary synchromesh type shift mechanism.

Case 1 corresponds to a non-contact condition, and when the sleeve gear SG is pressed to mesh with the clutch gear 2_ CG, the sleeve gear SG and the clutch gear 2_ CG meet while being precisely staggered with each other, and therefore, the sleeve gear SG directly meshes with the clutch gear 2_ CG while the chamfers of the sleeve gear SG and the clutch gear 2_ CG do not collide with each other, thereby completing a shifting operation.

Case 2 corresponds to a forward contact case, although the chamfer of the sleeve gear SG contacts the chamfer of the clutch gear 2_ CG while meeting the chamfer of the clutch gear 2_ CG, when the sleeve gear SG is pressed toward the clutch gear 2_ CG by the inclination angle defined when the two chamfers meet each other, the directional component of the guide sleeve gear SG coincides with the rotational direction of the sleeve gear SG and the sleeve gear SG can be easily inserted into the clutch gear 2_ CG, and thus the shifting operation is completed with the lapse of time without causing any problem.

However, case 3 corresponds to the case of the reverse contact, and the inclination angle defined when the two chamfers of the sleeve gear SG and the clutch gear 2_ CG meet each other is opposite to case 2, and therefore, when the inclination angle defined when the two chamfers meet each other presses the sleeve gear SG toward the clutch gear 2_ CG, the direction component of guiding the sleeve gear SG is opposite to the rotational direction of the sleeve gear SG, and therefore, even with the lapse of time, smooth meshing cannot be achieved.

In this case, the sleeve gear SG and the clutch gear 2_ CG may be coupled to each other by releasing the servo clutch SC to reduce the relative rotational force of the sleeve gear SG, and if such a state frequently occurs, when both chamfers of the sleeve gear SG and the clutch gear 2_ CG are deformed, damaged, or worn, the durability of the shift is deteriorated.

In an exemplary embodiment of the present invention, in order to solve the above-described problems occurring when the inclined chamfers are left in the axial direction of the sleeve gear SG and the clutch gear 2_ CG as described above, it is possible to solve the side effects of noise generation, damage and wear caused when the two chamfers meet and collide with each other by shaping the opposing portions of the sleeve gear SG and the clutch gear 2_ CG into simple planar shapes, and, although the sleeve gear SG and the clutch gear 2_ CG are in contact with each other without being arranged to be precisely staggered with each other so that the sleeve gear SG and the clutch gear 2_ CG are properly meshed with each other by themselves, the sleeve gear SG and the clutch gear 2_ CG can be easily meshed with each other even after a predetermined period of time elapses.

For reference, as shown in fig. 9, in a general transmission of a vehicle, when the difference between the RPM of the clutch gear 2_ CG and the RPM of the sleeve gear SG is about 2RPM, even if the sleeve gear SG and the clutch gear 2_ CG are not properly arranged and contact each other while meeting each other, a shift can be completed in about 0.2 seconds, which is not insufficient in rapidity of the shift.

The transmission ratio of the variable driving gear VD to the variable driven gear VP is smaller than the transmission ratio of the first driving gear DG1 to the first driven gear P1 and the transmission ratio of the second driving gear DG2 to the second driven gear P2.

That is, the transmission ratio of the variable driving gear VD to the variable driven gear VP is slightly smaller than the transmission ratio of the second driving gear DG2 to the second driven gear P2.

For example, if the gear ratio of the first driving gear DG1 to the first driven gear P1 is 3.5 and the gear ratio of the second driving gear DG2 to the second driven gear P2 is 2.8, the gear ratio of the variable driving gear VD to the variable driven gear VP is set to about 2.75.

The above setting makes it possible to easily and smoothly operate the sleeves 1&2_ SB when the sleeves 1&2_ SB of the first and second synchronizers 1&2S are released from the state where they are engaged with the clutch gear 1_ CG of the first driven gear P1 or the clutch gear 2_ CG of the second driven gear P2 to the neutral state.

When the sleeves 1&2_ SB of the first and second synchronizers 1&2S are released from the state in which they are engaged with the clutch gear 1_ CG of the first driven gear P1 or the clutch gear 2_ CG of the second driven gear P2, if the servo clutch SC is coupled so that torque is transmitted through the variable driving gear VD and the variable driven gear VP, a point of time when the RPM of the sleeve becomes the RPM of the clutch gear 1_ CG of the first driven gear P1 or the RPM of the clutch gear 2_ CG of the second driven gear P2 occurs, and thus, torque is not immediately applied to the sleeves 1&2_ SB and the clutch gears CG 1_ CG and 2_ SB, so that the sleeves 1&2_ SB can be smoothly withdrawn in a neutral state.

For reference, a smooth operation of the sleeve 1&2_ SB is achieved by the above operation by making the gear ratio of the variable driving gear VD and the variable driven gear VP smaller than the gear ratio of the first driven gear P1 of the first driving gear DG1 and the second driven gear P2 of the second driving gear DG2, whereby a smooth shift operation can be performed also in the case where the power of the motor M is continuously applied to the motor input shaft MI.

Hereinafter, a sequential shift process of the first to sixth gears will be described with reference to fig. 2A to 6C.

Fig. 2A to 2F show a process of shifting the first gear to the second gear, and fig. 2A shows a state where power of the engine is transmitted to the motor input shaft MI through the first clutch CL1 and is shifted to the first gear power through the first drive gear DG1 and the first driven gear P1 to be extracted to the differential DF IN a state where the sleeve of the central synchronizing unit CS connects the first input shaft IN1 to the motor input shaft MI and the first and second synchronizers 1&2S connect the first driven gear P1 to the first output shaft OUT 1.

If a command to shift into second gear is generated, servo clutch SC is caused to generate friction by releasing first clutch CL1 and disengaging the engine and moving center sleeve CSB of center synchronizing unit CS toward variable drive gear VD, as shown in fig. 2C, after motor M is driven and motor M develops first gear power.

When the rotational speed of the sleeve 1&2_ SB of the first and second synchronizers 1&2S starts to be greater than the rotational speed of the first driven gear P1, the sleeve 1&2_ SB is released as shown in fig. 2D, and the second gear drive state of the motor M is formed by coupling the sleeve 1&2_ SB to the clutch gear 2_ CG of the second driven gear P2.

Therefore, even if the sleeve gear SG of the sleeve 1&2_ SB and the clutch gear 2_ CG of the second driven gear P2 are not immediately engaged with each other (as described above), they are immediately engaged with each other when the frictional force of the servo clutch SC is further increased, and in the process, torque interruption does not occur because the power from the motor M is continuously transmitted to the first output shaft OUT1 through the variable driving gear VD and the variable driven gear VP.

Next, as shown IN fig. 2E, if the first clutch CL1 is coupled again after the center sleeve CSB is coupled to the clutch gear 3_ CG of the third driving gear DG3 and the first input shaft IN1 is connected to the motor input shaft MI, the second gear driving state is also formed by the power of the engine E, and as shown IN fig. 2F, if the driving of the motor M is released, the second gear driving state is formed only by the engine E.

Fig. 3A to 3C show the process of shifting the second gear to the third gear, and if a command to shift from the second gear drive state to the third gear is generated in the second gear drive state as in fig. 3A, in a state where the third driven gear P3 is connected to the second output shaft OUT2 through the third and sixth synchronizers 3&6S as in fig. 3B, a shift to the third gear drive state of the engine E is completed by releasing the first clutch CL1 while the second clutch CL2 is engaged (as in fig. 3C).

Fig. 4A to 4C show a process of shifting the third gear to the fourth gear, and if a command for shifting to the fourth gear is generated in the third gear driving state as in fig. 4A, in a state where the fourth driven gear P4 is connected to the first output shaft OUT1 through the fourth and fifth synchronizers 4&5S as in fig. 4B, a shift to the fourth gear driving state of the engine E is completed by releasing the second clutch CL2 while the first clutch CL1 is engaged (as in fig. 4C).

Fig. 5A to 5E show a process of shifting the fourth gear to the fifth gear, and if a command for shifting the fourth gear drive state to the fifth gear is generated as in fig. 5A, power in the fourth gear is transmitted to the first output shaft OUT1 by driving the motor M, also through the second drive gear DG2 and the second driven gear P2 as in fig. 5B.

Thereafter, as shown in fig. 5C, when the fourth-gear driving state is maintained only by the driving force of the motor M by releasing the first clutch CL1, the fifth driven gear P5 is connected to the first output shaft OUT1 by releasing the fourth and fifth synchronizers 4&5S from the fourth driven gear P4.

Thereafter, if the second clutch CL2 is engaged, the fifth gear driving state is formed by the power of the engine E, as in fig. 5D, and if the motor M is not connected, the fifth gear driving state is realized only by the power of the engine E, as in fig. 5E.

In the example embodiment of the invention, during the shift from the fourth gear to the fifth gear, the fourth and fifth synchronizers 4&5S are released from the fourth driven gear P4, and the fifth driven gear P5 is connected again to the first output shaft OUT1 via the neutral state, the process of which results in the power from the engine E not being transmitted to the drive wheels and interrupted torque interruption, but by achieving the state in which the power is continuously transmitted to the first output shaft OUT1 by the motor M, a smooth shift feeling without torque interruption can be ensured.

Fig. 6A to 6C show a process of shifting from fifth gear to sixth gear, and if a command to shift from fifth gear drive state to sixth gear is generated in fifth gear drive state as in fig. 6A, after the sixth driven gear P6 is connected to the second output shaft OUT2 through the third and sixth synchronizers 3&6S as in fig. 6B, the sixth gear drive state as in fig. 6C is formed by releasing the second clutch CL2 while the first clutch CL1 is engaged.

Meanwhile, fig. 7A to 7D show a process of shifting the first EV range to the second EV range of the electric vehicle mode, and the state of fig. 7A is a state in which: wherein the sleeves 1&2_ SB of the first and second synchronizers 1&2S are engaged with the clutch gear 1_ CG of the first driven gear P1, and the power of the motor M supplied to the motor input shaft MI is extracted to the differential DF by the first drive gear DG1 and the first driven gear P1.

If a command for second EV gear shifting is generated, the power of the motor M starts to be transmitted to the first output shaft OUT1 through the variable driving gear VD and the variable driven gear VP as well as the center sleeve CSB of the center synchronizing unit CS is attached to the variable driving gear VD to generate a frictional force of the servo clutch SC, as shown in fig. 7B.

When the rotational speed of the sleeve 1&2_ SB of the first and second synchronizers 1&2S starts to be greater than the rotational speed of the first driven gear P1, the sleeve 1&2_ SB is smoothly released, and the second EV-range driving state is formed by coupling the sleeve 1&2_ SB to the clutch gear 2_ CG of the second driven gear P2 as shown in fig. 7C.

Therefore, even if the sleeve gear SG of the sleeve 1&2_ SB and the clutch gear 2_ CG of the second driven gear P2 are not immediately engaged with each other (as described above), they are immediately engaged with each other when the frictional force of the servo clutch SC is further increased, and in the process, torque interruption does not occur because the power from the motor M is continuously transmitted to the first output shaft OUT1 through the variable driving gear VD and the variable driven gear VP.

Next, if the servo clutch SC is released by moving the center sleeve CSB of the center synchronizing unit CS to the neutral state, the second EV range driving state is formed while the power of the motor M is transmitted to the first output shaft OUT1 only through the second driving gear DG2 and the second driven gear P2 as shown in fig. 7D.

The first EV gear and the second EV gear of fig. 7A to 7D can be respectively operated to the reverse gear by rotating the motor M in the reverse direction.

Meanwhile, it is apparent that the hybrid power train of the present invention may be implemented in a hybrid mode for assisting the power of the engine E when the motor M is driven together for all of the first through sixth gears, in which the power is extracted through the first output shaft OUT1 or the second output shaft OUT2 using the power of the engine E.

For convenience in explanation and accurate definition in the appended claims, the terms "upper", "lower", "inner", "outer", "upper", "lower", "upward", "downward", "front", "back", "rear", "inner", "outer", "inward", "outward", "inner", "outer", "inboard", "outboard", "forward", "rearward" are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. It will be further understood that the term "coupled," or derivatives thereof, means both directly and indirectly coupled.

Furthermore, the term "fixedly connected" means that the fixedly connected components always rotate at the same speed. Furthermore, the term "selectively connectable" means: the selectively connectable members rotate apart when the selectively connectable members are not engaged with each other, rotate at the same speed when the selectively connectable members are engaged with each other, and are stationary when at least one of the selectively connectable members is a stationary member and the remaining selectively connectable members are engaged to the stationary member.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. The foregoing description is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable others skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the following claims and their equivalents.