Hybrid powertrain for vehicles

Abstract

The present invention relates to a hybrid powertrain for a vehicle, which may include: a first input shaft, which is selectively connectable to an engine through a first clutch; a second input shaft, which is selectively connectable to the engine through a second clutch and is installed coaxially with the first input shaft; a motor input shaft, which is installed coaxially with the first input shaft and to which the motor is connected; a first output shaft and a second output shaft, each of which is installed parallel to the first input shaft and the second input shaft; a central synchronizing unit, which is installed between the first input shaft and the motor input shaft and is configured to interrupt the connection between the first input shaft and the motor input shaft; multiple pairs of external gears, which are configured to form a series of gear ratios for vehicle travel; and a variable transmission mechanism.

Description

Technical Field

[0001] The present invention relates to a technology for a layout of a hybrid powertrain that can be applied to a vehicle. Background Art

[0002] A transmission mounted electric device (TMED) hybrid powertrain is a powertrain in which the electric motor is not mounted on the engine but on the transmission.

[0003] Generally, among the above-mentioned TMED hybrid powertrains, the TMED hybrid powertrain that connects the engine and the motor by utilizing an engine clutch has been widely used, but for the powertrain, providing the engine clutch requires costs, and when the engine clutch is connected, the rotational speeds of the engine and the motor must be the same. Since the shift map is set according to the optimal operating point of the engine, the main operating area is concentrated in the low-speed area, so the performance of the motor cannot be fully realized. Moreover, since the motor is located close to the input side of the transmission, during regenerative braking, the power transmission path from the drive wheels to the motor becomes complicated, thereby reducing the regenerative braking efficiency.

[0004] The information disclosed in the background technology section of the present invention is only intended to enhance the understanding of the overall background of the present invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. Summary of the Invention

[0005] Various aspects of the present invention are directed to providing a hybrid powertrain for a vehicle, which can reduce the manufacturing cost and weight of the hybrid powertrain for a vehicle by eliminating an engine clutch for interrupting the connection between the engine and the motor, and can achieve optimal operation of the motor and the engine by controlling the motor independently of the engine, and can make the power transmission path between the motor and the drive wheels during regenerative braking shorter, thereby improving the efficiency of the hybrid powertrain in EV mode and during regenerative braking.

[0006] According to one aspect of the present invention, a hybrid powertrain for a vehicle may include: a first input shaft selectively connectable to an engine via a first clutch; a second input shaft selectively connectable to the engine via a second clutch and mounted coaxially with the first input shaft; a motor input shaft mounted coaxially with the first input shaft and having a motor connected to the motor input shaft; first and second output shafts, each of the first and second output shafts being mounted parallel to the first and second input shafts; a central synchronizing unit mounted 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; multiple pairs of external gears mounted between the motor input shaft and the first output shaft, between the first 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 utilizing the central synchronizing unit and transmit the changed power to the first output shaft.

[0007] The variable transmission mechanism may include: a variable driving gear rotatably mounted on the motor input shaft; a variable driven gear fixedly connected to the first output shaft to engage with the variable driving gear; and a servo clutch configured to continuously change the friction between the motor input shaft and the variable driving gear through operation of a central synchronization unit.

[0008] The servo clutch may be of a conical friction clutch type, and the conical surface of the servo clutch may be integrally formed with the variable drive gear.

[0009] The central synchronization unit may include: a central hub portion, which is mounted on the motor input shaft; a central sleeve, which is configured to slide on the central hub portion along the axial direction of the central sleeve; and a synchronizer may be provided, which is connected to the first input shaft through synchronization by a synchronizer ring when the central sleeve moves to one axial side thereof; and when the central sleeve moves to the second direction, the central sleeve may press the conical surface of the variable drive gear.

[0010] The external gear pair between the motor input shaft and the first output shaft can be used for the first gear transmission ratio and the second gear transmission ratio respectively, the external gear pair between the first input shaft and the first output shaft can be used for the fourth gear transmission ratio, the external gear pair between the first input shaft and the second output shaft can be used for the sixth gear transmission ratio, the external gear pair between the second input shaft and the first output shaft can be used for the fifth gear transmission ratio, and the external gear pair between the second input shaft and the second output shaft can be used for the third gear transmission ratio.

[0011] The first drive gear for the first gear transmission ratio and the second drive gear for the second gear transmission ratio can be installed on the motor input shaft, the first driven gear meshing with the first drive gear and the second driven gear meshing with the second drive gear can be installed on the first output shaft, the third drive gear commonly used for the fourth gear transmission ratio and the sixth gear transmission ratio can be installed on the first input shaft, the fourth drive gear commonly used for the third gear transmission ratio and the fifth gear transmission ratio can be installed on the second input shaft, the fourth driven gear meshing with the third drive gear and the fifth driven gear meshing with the fourth drive gear can be installed on the first output shaft, the sixth driven gear meshing with the third drive gear and the third driven gear meshing with the fourth drive gear can be installed on the second output shaft.

[0012] The first drive gear and the second drive gear can be installed on the motor input shaft so that the rotation of the first drive gear and the rotation of the second drive gear are constrained, the third drive gear can be installed on the first input shaft so that the rotation of the third drive gear is constrained, and the fourth drive gear is installed on the second input shaft so that the rotation of the fourth drive gear can be constrained. The first and second synchronizers configured to selectively constrain the rotation of the first driven gear and the rotation of the second driven gear can be set on the first output shaft, and the fourth and fifth synchronizers configured to selectively constrain the rotation of the fourth driven gear and the rotation of the fifth driven gear can be set on the first output shaft, and the third and sixth synchronizers configured to selectively constrain the rotation of the third driven gear and the rotation of the sixth driven gear can be set on the second output shaft.

[0013] A synchronizer configured to perform synchronization by utilizing 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.

[0014] Opposing 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.

[0015] A transmission ratio of the variable drive gear to the variable driven gear may be smaller than a transmission ratio of the first drive gear to the first driven gear and a transmission ratio of the second drive gear to the second driven gear.

[0016] A clutch gear engaged with the central sleeve of the central synchronization unit may be integrally formed with the third drive gear.

[0017] 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.

[0018] According to an exemplary embodiment of the present invention, by eliminating an engine clutch for interrupting the connection between the engine and the motor, the manufacturing cost and weight of a hybrid powertrain for a vehicle can be reduced, and by controlling the motor independently of the engine, the motor and the engine can be optimally operated, and the power transmission path between the motor and the drive wheels during regenerative braking can be shortened, thereby improving the efficiency of the hybrid powertrain in EV mode and during regenerative braking.

[0019] The methods and apparatus of the present invention have other features and advantages that will be apparent from or are set forth in detail in the accompanying drawings and subsequent detailed description incorporated herein, which together serve to explain the specific principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 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;

[0021] 2A, 2B, 2C, 2D, 2E and 2F illustrate the Figure 1 Schematic diagram of a powertrain shifting from a first gear to a second gear;

[0022] 3A, 3B and 3C illustrate the Figure 1 Schematic diagram of a powertrain shifting from second gear to third gear;

[0023] 4A, 4B and 4C illustrate the Figure 1 Schematic diagram of a power train shifting from third gear to fourth gear;

[0024] 5A, 5B, 5C, 5D and 5E illustrate the Figure 1 Schematic diagram of a power train shifting from fourth gear to fifth gear;

[0025] FIG. 6A , FIG. 6B and FIG. 6C illustrate the Figure 1 Schematic diagram of a power train shifting from fifth gear to sixth gear;

[0026] 7A, 7B, 7C and 7D illustrate the Figure 1 Schematic diagram of a powertrain shifting from a first EV gear to a second EV gear;

[0027] Figure 8 for Figure 1 a sectional view of a main portion of a first synchronizer and a second synchronizer;

[0028] Figure 9 For the Figure 8 Table comparing operations of the first synchronizer and the second synchronizer with the prior art.

[0029] It should be understood that the accompanying drawings are not necessarily drawn to scale, but rather show a somewhat simplified representation of various features illustrating the basic principles of the invention. The specific design features of the present invention (including, for example, specific dimensions, orientations, locations, and shapes) will be determined in part by the specific intended application and use environment.

[0030] In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. DETAILED DESCRIPTION

[0031] 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. Although the present invention will be described in conjunction with exemplary embodiments of the present invention, it will be understood that this specification is not intended to limit the present invention to those exemplary embodiments. On the other hand, the present invention is intended to cover not only the exemplary embodiments of the present invention, but also various alternatives, modifications, equivalents and other embodiments that may be included within the spirit and scope of the present invention as defined by the appended claims.

[0032] refer to Figure 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 synchronization unit CS, multiple external gears, and a variable transmission mechanism; the first input shaft IN1 is connected to the engine E through a first clutch CL1; the second input shaft IN2 is connected to the engine E through a second clutch CL2 and is installed to be coaxial with the first input shaft IN1; the motor input shaft MI is installed to be coaxial with the first input shaft IN1, and the motor M is connected to the motor input shaft MI; the first output shaft OUT1 and the second output shaft OUT2 are installed parallel to the first input shaft input shaft IN1 and the second input shaft IN2; the central synchronization unit CS is configured to interrupt the connection between the first input shaft IN1 and the motor input shaft MI; multiple 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 driving; the variable transmission mechanism is configured to continuously change the power of the motor input shaft MI by utilizing the central synchronization unit CS and transmit the changed power to the first output shaft OUT1.

[0033] That is, in the exemplary embodiment of the present invention, the vehicle is configured to achieve a series of gear ratios from the first gear to the sixth gear using a plurality of pairs of external gears by power transmitted from the engine E or the motor M.

[0034] The first clutch CL1 and the second clutch CL2 include a dual clutch DCL formed in a clutch housing, the second input shaft IN2 is a hollow shaft surrounding 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 jointly engaged with the ring gear RG of the differential DF.

[0035] That is, according to the power transmission system of the present invention, when the first input shaft IN1 and the second input shaft IN2 transmit the power of the engine E received through the first clutch CL1 and the second clutch CL2 of the dual clutch DCL to the first output shaft OUT1 and the second output shaft OUT2, the third gear to the sixth gear can be achieved, and 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 gear and the second gear can be achieved, and the power of the gears achieved as described above can be extracted by the differential DF, and during the gear shifting operation, smooth gear shifting can be performed without any torque interruption through the gear shifting to be described below.

[0036] In addition, because the motor M is not installed in the engine E through the engine clutch and therefore the engine clutch is not installed, the manufacturing cost of the vehicle can be reduced and the weight can be reduced, because the motor can be controlled independently of the engine, the control freedom of the motor M can be higher, and because in EV mode or during regenerative braking, power can be transmitted between the motor M and the drive wheels through a relatively short power transmission path, the power transmission efficiency can be higher.

[0037] 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 on the motor input shaft MI; the variable driven gear VP is mounted on the first output shaft OUT1 to engage with the variable drive gear VD; the servo clutch SC is configured to continuously change the friction between the motor input shaft MI and the variable drive gear VD through the operation of the central synchronization unit CS.

[0038] The servo clutch SC is of a cone friction clutch type, and a cone surface CN of the servo clutch SC is formed integrally with the variable drive gear VD.

[0039] Of course, not only the cone friction clutch but also various friction clutches such as a general flat plate friction clutch can be used as the servo clutch SC.

[0040] The central synchronization unit includes a central hub CHB and a central sleeve CSB, the central hub CHB is mounted 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 synchronization unit is provided with a synchronizer, when the central sleeve CSB moves to one axial side thereof, the synchronizer is connected to the first input shaft IN1 through synchronization of the synchronizer, and when the central sleeve CSB moves to its opposite axial side, the central sleeve CSB squeezes the conical surface CN of the variable drive gear VD.

[0041] Here, the "axial direction" refers to the longitudinal direction of the motor input shaft MI.

[0042] refer to Figure 1 As shown on the left side of the central synchronization unit CS, a third drive gear DG3 is installed while its rotation is constrained by the first input shaft IN1, and a clutch gear 3_CG that can engage with the central sleeve CSB of the central synchronization unit CS is integrally provided on the third drive gear DG3.

[0043] The synchronizer ring is provided between the clutch gear 3_CG of the third drive gear DG3 and the center sleeve CSB, and the center sleeve CSB is engaged with the clutch gear 3_CG of the third drive gear DG3 by synchronization of a synchromesh type synchronizer.

[0044] For reference, the same type of synchronizer ring as the conventional common synchromesh type synchronizer can be used, and Figure 1 The illustration is omitted.

[0045] At the same time, the servo clutch SC is arranged on the right side of the central synchronization unit CS, and the central sleeve CSB of the central synchronization unit CS can be configured to attach the conical friction ring to the conical surface CN of the variable drive gear VD, and another conical surface can be formed on the right inner side of the central sleeve CSB so that the conical surface of the central sleeve CSB can be directly attached to the conical surface CN of the variable drive gear VD.

[0046] In addition, by setting up an operating force increasing mechanism, the capacity of the actuator driving the central sleeve CSB can be reduced and the friction force of the servo clutch SC can be fully ensured. The operating force increasing mechanism increases the axial operating force of the central sleeve CSB between the central sleeve CSB and the friction ring so that the friction ring is attached to the conical surface CN of the variable drive gear VD.

[0047] A pair of external gears between the motor input shaft MI and the first output shaft OUT1 are used for the first gear ratio and the second gear ratio respectively, a pair of external gears between the first input shaft IN1 and the first output shaft OUT1 are used for the fourth gear ratio, and a pair of external gears between the first input shaft IN1 and the second output shaft OUT2 are used for the sixth gear ratio, wherein a pair of external gears between the second input shaft IN2 and the first output shaft OUT1 are used for the fifth gear ratio, and a pair of external gears between the second input shaft IN2 and the second output shaft OUT2 are used for the third gear ratio.

[0048] That is, the first drive gear DG1 for the first gear ratio and the second drive gear DG2 for the second gear ratio are installed on the motor input shaft MI, the first driven gear P1 meshing with the first drive gear DG1 and the second driven gear P2 meshing with the second drive gear DG2 are installed on the first output shaft OUT1, the third drive gear DG3 commonly used for the fourth gear ratio and the sixth gear ratio is installed on the first input shaft IN1, the fourth drive gear DG4 commonly used for the third gear ratio and the fifth gear ratio is installed on the second input shaft IN2, the fourth driven gear P4 meshing with the third drive gear DG3 and the fifth driven gear P5 meshing with the fourth drive gear DG4 are installed on the first output shaft OUT1, and the sixth driven gear P6 meshing with the third drive gear DG3 and the third driven gear P3 meshing with the fourth drive gear DG4 are installed on the second output shaft OUT2.

[0049] The first drive gear DG1 and the second drive gear DG2 are installed on the motor input shaft MI so that their rotation is constrained, the third drive gear DG3 is installed on the first input shaft IN1 so that its rotation is constrained, and the fourth drive gear DG4 is installed on the second input shaft IN2 so that its rotation is constrained. The first and second synchronizers 1&2S configured to selectively constrain the rotation of the first driven gear P1 and the second driven gear P2 and the fourth and fifth synchronizers 4&5S configured to selectively constrain the rotation of the fourth driven gear P4 and the fifth driven gear P5 are arranged on the first output shaft, and the third and sixth synchronizers 3&6S configured to selectively constrain the rotation of the third driven gear P3 and the sixth driven gear P6 are arranged on the second output shaft OUT2.

[0050] Here, the third and sixth synchronizers 3&6S and the fourth and fifth synchronizers 4&5S are respectively provided with synchronizer rings on opposite sides of the hub, so that when the sleeves engage with the gears located on opposite sides of the hub, they can smoothly engage with each other through synchronization.

[0051] 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 is provided between the first and second synchronizers 1&2S and the second driven gear P2, in which the sleeves 1&2_SB of the first and second synchronizers 1&2S are directly engaged with the clutch gear of the second driven gear.

[0052] That is, the first and second synchronizers 1 & 2S are provided with a synchronizer on a side close to the first driven gear P1 , but are provided with a dog clutch on a side close to the second driven gear P2 , and the dog clutch does not include a synchronizer ring.

[0053] In addition, if Figure 8 As shown, 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.

[0054] 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 have a plane shape perpendicular to the axial direction thereof means that: Figure 8 As shown on the right side of , the clutch gear 2_CG of the second driven gear P2 and the end of the sleeve gear SG of the sleeve 1&2_SB facing the clutch gear 2_CG form a plane shape (X, Y) facing each other.

[0055] Figure 8 It is a cross-sectional view taken along the circumferential direction of the hub 1&2_HB around the center line at which the hub 1&2_HB and the sleeve 1&2_SB of the first and second synchronizers 1&2S are spline-coupled to each other and Figure 8 The middle part shows the sleeve gears SG of the hub 1&2_HB and the sleeve 1&2_SB are installed alternately. Figure 8 The clutch gear 2_CG of the second driven gear P2 is shown on the right side of Figure 8 The left side of is shown with the clutch gear 1_CG and the synchronizer ring SR of the first driven gear P1.

[0056] As described above, as shown in the figure, the synchronizer ring SR is installed between the first driven gear P1 and the hub 1&2_HB, and the clutch gear 1_CG of the first driven gear P1 has a chamfer that is axially inclined toward the sleeve gear SG as in a conventional ordinary synchronized meshing shift mechanism, and an axially installed chamfer is also provided in the sleeve gear SG.

[0057] Therefore, when shifting is performed by sliding the sleeve 1 & 2_SB from the neutral state corresponding to the central portion of the hub 1 & 2_HB toward the first driven gear P1, shifting is performed in the same manner as in the conventionally known technology.

[0058] Meanwhile, a process of performing a shift operation to engage the sleeve 1 & 2_SB with the second driven gear P2 is different from that of the conventional art.

[0059] First, before sleeve 1&2_SB comes into contact with the second driven gear P2, synchronization is performed by engaging the servo clutch SC. Specifically, because a separate synchronizer ring is not provided as in conventional technology, synchronization is not performed using a synchronizer ring. However, the gear ratio between the variable drive gear VD and the variable driven gear VP (as will be described below) is slightly smaller than the gear ratio between the second drive gear DG2 and the second driven gear P2. Therefore, when the servo clutch SC is engaged, time is taken for synchronization, and thereafter, there is little difference in relative speed.

[0060] When synchronization is achieved, 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 Figure 9 The two situations are shown on the lower side.

[0061] That is, the two situations correspond to the situation on the left and the situation on the right. In the situation on the left, the sleeve gear SG and the clutch gear 2_CG meet each other and are precisely staggered with each other to immediately engage with each other without blocking each other, thereby completing the shifting operation. In the situation on the right, the plane shapes meet each other and collide with each other.

[0062] As shown in the figure, when the planar shape of the sleeve gear SG and the planar shape of the clutch gear 2_CG meet and collide with each other, due to the slight difference between the gear ratios as described below, the RPM of the sleeve gear SG is slightly larger than the RPM of the clutch gear 2_CG. Therefore, the sleeve gear SG and the clutch gear 2_CG meet while being precisely staggered with each other to precisely engage with each other as a predetermined time period elapses.

[0063] For reference, to simply compare the RPM of the clutch gear 2_CG with the RPM of the sleeve gear SG, Figure 9 The difference between the relative rotation speeds of the clutch gear 2_CG and the sleeve gear SG is shown by expressing the RPMω of the clutch gear 2_CG as 0 RPM and the RPMω of the sleeve gear SG as 2 RPM.

[0064] at the same time, Figure 9The upper side shows three different situations in which shifting operations are performed in a conventional general structure, wherein the relative 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 relative to the axial direction as in a conventional general synchronous meshing shifting mechanism.

[0065] Case 1 corresponds to a non-contact situation, and when the sleeve gear SG is pressed to engage with the clutch gear 2_CG, the sleeve gear SG and the clutch gear 2_CG meet while being precisely staggered with each other, so the sleeve gear SG is directly engaged with the clutch gear 2_CG, and the chamfers of the sleeve gear SG and the clutch gear 2_CG do not collide with each other, thereby completing the gear shifting operation.

[0066] Case 2 corresponds to the forward contact situation. Although the chamfer of the sleeve gear SG contacts the chamfer of the clutch gear 2_CG at the same time as it meets the chamfer of the clutch gear 2_CG, 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 the guide sleeve gear SG is consistent with the rotation direction of the sleeve gear SG and the sleeve gear SG can be easily inserted into the clutch gear 2_CG, so that the shifting operation is completed over time without causing any problems.

[0067] However, Case 3 corresponds to a situation of 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 that of Case 2. 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 guiding the sleeve gear SG is opposite to the rotation direction of the sleeve gear SG, and therefore, smooth engagement cannot be achieved even over time.

[0068] In this case, the sleeve gear SG and the clutch gear 2_CG can be connected to each other by loosening the servo clutch SC to reduce the relative rotational force of the sleeve gear SG, and if this state occurs frequently, the durability of the gear shifting becomes worse when the two chamfers of the sleeve gear SG and the clutch gear 2_CG are deformed, damaged or worn.

[0069] In an exemplary embodiment of the present invention, in order to solve the above-mentioned problem that occurs when an inclined chamfer is left in the axial direction of the sleeve gear SG and the clutch gear 2_CG as described above, the side effects of generating noise, causing damage and wear when the two chamfers meet and collide with each other can be solved by making the shapes of the relative parts of the sleeve gear SG and the clutch gear 2_CG a simple plane shape, 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 so that the sleeve gear SG and the clutch gear 2_CG can properly engage with each other by themselves, the sleeve gear SG and the clutch gear 2_CG can easily engage with each other even after a predetermined period of time has passed.

[0070] For reference, Figure 9 As shown, in an ordinary 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, the gear shifting can be completed in about 0.2 seconds, which is not insufficient in terms of the speed of the gear shifting.

[0071] The transmission ratio of the variable drive gear VD to the variable driven gear VP is smaller than the transmission ratio of the first drive gear DG1 to the first driven gear P1 and the transmission ratio of the second drive gear DG2 to the second driven gear P2.

[0072] That is, the transmission ratio of the variable drive gear VD to the variable driven gear VP is slightly smaller than the transmission ratio of the second drive gear DG2 to the second driven gear P2.

[0073] For example, if the gear ratio of the first drive gear DG1 to the first driven gear P1 is 3.5 and the gear ratio of the second drive gear DG2 to the second driven gear P2 is 2.8, the gear ratio of the variable drive gear VD to the variable driven gear VP is set to about 2.75.

[0074] The above setting enables easy and smooth operation of the sleeves 1 & 2_SB when the sleeves 1 & 2_SB of the first and second synchronizers 1 & 2S are released from their engagement 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 a neutral state.

[0075] 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 connected so that the torque is transmitted through the variable drive gear VD and the variable driven gear VP, there will be a time point 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, so that the torque is not immediately applied to the sleeve 1&2_SB and the clutch gears 1_CG and 2_CG, so that the sleeve 1&2_SB can be smoothly withdrawn in the neutral state.

[0076] For reference, the smooth operation of the sleeve 1&2_SB is achieved through the above operation by making the transmission ratio of the variable drive gear VD and the variable driven gear VP smaller than the transmission ratio of the first driven gear P1 of the first drive gear DG1 and the second driven gear P2 of the second drive gear DG2. Thus, smooth gear shifting operation can be performed even when the power of the motor M is continuously applied to the motor input shaft MI.

[0077] Hereinafter, a sequential shifting process of the first gear to the sixth gear will be described with reference to FIG. 2A to FIG. 6C .

[0078] Figures 2A to 2F show the process of shifting from the first gear to the second gear, and Figure 2A shows the state in which the power of the engine is transmitted to the motor input shaft MI through the first clutch CL1 and shifted to the first gear power through the first drive gear DG1 and the first driven gear P1, so as to be extracted to the differential DF in the state in which the sleeve of the central synchronization 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 OUT1.

[0079] If a shift command to the second gear is generated, after the motor M is driven and the motor M forms the first gear power, as shown in FIG2C , the servo clutch SC generates friction by releasing the first clutch CL1 and separating the engine and moving the central sleeve CSB of the central synchronization unit CS toward the variable drive gear VD.

[0080] 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, as shown in Figure 2D, the sleeve 1&2_SB is released, and the second gear driving state of the motor M is formed by connecting the sleeve 1&2_SB to the clutch gear 2_CG of the second driven gear P2.

[0081] 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 do not immediately engage with each other as described above, they will immediately engage with each other on their own when the friction force of the servo clutch SC further increases, and in this process, because the power from the motor M is continuously transmitted to the first output shaft OUT1 through the variable drive gear VD and the variable driven gear VP, no torque interruption occurs.

[0082] Next, as shown in Figure 2E, if the first clutch CL1 is connected again after the central sleeve CSB is connected to the clutch gear 3_CG of the third drive 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 Figure 2F, if the drive of the motor M is released, the second gear driving state is formed only by the engine E.

[0083] Figures 3A to 3C show the process of shifting from the second gear to the third gear. As shown in Figure 3A, if an instruction to shift from the second gear driving state to the third gear is generated in the second gear driving state, then as shown in Figure 3B, 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, the first clutch CL1 is released while the second clutch CL2 is connected to complete the shift to the third gear driving state of the engine E (as shown in Figure 3C).

[0084] Figures 4A to 4C show the process of shifting from the third gear to the fourth gear. As shown in Figure 4A, if an instruction to shift to the fourth gear is generated in the third gear driving state, then as shown in Figure 4B, 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, the shift to the fourth gear driving state of the engine E is completed by coupling the first clutch CL1 while releasing the second clutch CL2 (as shown in Figure 4C).

[0085] Figures 5A to 5E show the process of shifting from the fourth gear to the fifth gear. As shown in Figure 5A, if an instruction to shift the fourth gear driving state to the fifth gear is generated, then as shown in Figure 5B, the fourth gear power is transmitted to the first output shaft OUT1 through the driving motor M and also through the second driving gear DG2 and the second driven gear P2.

[0086] 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 .

[0087] 5D , if the second clutch CL2 is connected, the fifth gear driving state is formed by the power of the engine E, and as shown in FIG. 5E , if the motor M is not connected, the fifth gear driving state is achieved only by the power of the engine E.

[0088] In an exemplary embodiment of the present invention, during the shifting from the fourth gear to the fifth gear, the fourth and fifth synchronizers 4&5S are released from the fourth driven gear P4, and via the neutral state, the fifth driven gear P5 is connected to the first output shaft OUT1 again. The process of the above state causes the power from the engine E not to be transmitted to the drive wheels and the torque is interrupted. However, by achieving a state in which the power is continuously transmitted to the first output shaft OUT1 by the motor M, a smooth shifting feel without torque interruption can be ensured.

[0089] Figures 6A to 6C show the process of shifting from the fifth gear to the sixth gear. As shown in Figure 6A, if an instruction to shift from the fifth gear driving state to the sixth gear is generated in the fifth gear driving state, then as shown in Figure 6B, after the sixth driven gear P6 is connected to the second output shaft OUT2 through the third and sixth synchronizers 3&6S, the second clutch CL2 is released while the first clutch CL1 is connected to form the sixth gear driving state as shown in Figure 6C.

[0090] At the same time, Figures 7A to 7D show the process of shifting from the first EV gear to the second EV gear in the electric vehicle mode. The state of Figure 7A is a state in which 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 provided to the motor input shaft MI is extracted to the differential DF through the first drive gear DG1 and the first driven gear P1.

[0091] If a command to shift to the second EV gear is generated, as shown in Figure 7B, the power of the motor M also begins to be transmitted to the first output shaft OUT1 through the variable drive gear VD and the variable driven gear VP, and at the same time, the central sleeve CSB of the central synchronization unit CS is attached to the variable drive gear VD to enable the servo clutch SC to generate friction.

[0092] 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 loosened, and as shown in FIG7C , the second EV gear driving state is formed by connecting the sleeve 1&2_SB to the clutch gear 2_CG of the second driven gear P2.

[0093] 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 do not immediately engage with each other as described above, they will immediately engage with each other on their own when the friction force of the servo clutch SC further increases, and in this process, because the power from the motor M is continuously transmitted to the first output shaft OUT1 through the variable drive gear VD and the variable driven gear VP, no torque interruption occurs.

[0094] Next, if the servo clutch SC is released by moving the central sleeve CSB of the central synchronization unit CS to the neutral state, as shown in Figure 7D, the second EV gear driving state is formed when the power of the motor M is transmitted to the first output shaft OUT1 only through the second drive gear DG2 and the second driven gear P2.

[0095] The first EV gear position and the second EV gear position of FIG. 7A to FIG. 7D may be respectively operated to a reverse gear position by rotating the motor M in reverse.

[0096] At the same time, it is obvious that for all gears from the first gear to the sixth gear, the hybrid power transmission system of the present invention can be implemented in a hybrid mode to assist the power of the engine E when driving the motor M together, wherein the power of the engine E is extracted through the first output shaft OUT1 or the second output shaft OUT2.

[0097] For ease of explanation and precise definition in the appended claims, the terms "upper," "lower," "inner," "outer," "above," "below," "upward," "downward," "front," "back," "rear," "inner," "outer," "inwardly," "outwardly," "inner," "external," "inside," "outside," "forward," and "rearward" are used to describe features of the exemplary embodiments with reference to the positions of such features as shown in the accompanying drawings. It will be further understood that the term "connect" or its derivatives refers to both direct and indirect connections.

[0098] Furthermore, the term "fixedly connected" means that the fixedly connected members always rotate at the same speed. Furthermore, the term "selectively connectable" means that the selectively connectable members rotate separately when not engaged with each other, rotate at the same speed when 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 with the stationary member.

[0099] The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. The foregoing descriptions are not intended to be exhaustive, nor are they intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described to illustrate the specific principles of the invention and their practical application, so that others skilled in the art can realize and utilize the various exemplary embodiments of the invention and various alternative forms and modifications thereof. The scope of the invention is intended to be defined by the appended claims and their equivalents.

Claims

1. A powertrain for a vehicle, the powertrain comprising: a first input shaft selectively connectable to the engine via a first clutch; a second input shaft selectively connectable to the engine via 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 the 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 mounted between the first input shaft and the motor input shaft and configured to interrupt the connection between the first input shaft and the motor input shaft; a plurality of gears mounted between the motor input shaft and the first output shaft, between the first 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 the power of the motor input shaft by utilizing a central synchronization unit and transmit the changed power to the first output shaft, Wherein, the variable transmission mechanism includes: a variable drive gear rotatably mounted on the motor input shaft; a variable driven gear fixedly connected to the first output shaft and meshing with the variable drive gear; and A servo clutch is configured to continuously vary the friction between the motor input shaft and the variable drive gear through operation of a central synchronization unit.

2. The powertrain for a vehicle according to claim 1, wherein: The servo clutch is a cone friction clutch; The tapered surface of the servo clutch is integrally formed with the variable drive gear.

3. The powertrain for a vehicle according to claim 2, wherein: The central synchronization unit comprises: a central hub mounted on the motor input shaft; a central sleeve mounted to slide on the central hub in an axial direction of the central sleeve; and a synchronizer connected to the first input shaft by a synchronizer ring through synchronization when the central sleeve moves in the first direction; Wherein, the central sleeve is configured to press the conical surface of the variable drive gear when the central sleeve moves in the second direction.

4. The powertrain for a vehicle according to claim 3, wherein: The plurality of gears include a first gear set, a second gear set, a third gear set, a fourth gear set, and a fifth gear set. in: A first gear set between the motor input shaft and the first output shaft is used for a first gear transmission ratio and a second gear transmission ratio respectively; A second gear set between the first input shaft and the first output shaft is used for a fourth gear ratio; A third gear set between the first input shaft and the second output shaft is used for a sixth gear ratio; A fourth gear set between the second input shaft and the first output shaft is used for a fifth gear ratio; A fifth gear set between the second input shaft and the second output shaft is used for a third gear ratio.

5. The powertrain for a vehicle according to claim 4, wherein: The first gear set includes a first drive gear and a second drive gear, and the first drive gear for the first gear transmission ratio and the second drive gear for the second gear transmission ratio are mounted on the motor input shaft; A first driven gear meshing with the first driving gear and a second driven gear meshing with the second driving gear are mounted on the first output shaft; The second gear set and the third gear set include a third drive gear mounted on the first input shaft and commonly used for the fourth gear ratio and the sixth gear ratio; The fourth gear set and the fifth gear set include a fourth drive gear mounted on the second input shaft and commonly used for the third gear ratio and the fifth gear ratio; A fourth driven gear meshing with the third drive gear and a fifth driven gear meshing with the fourth drive gear are mounted on the first output shaft; A sixth driven gear meshing with the third drive gear and a third driven gear meshing with the fourth drive gear are mounted on the second output shaft.

6. The powertrain for a vehicle according to claim 5, wherein: The first drive gear and the second drive gear are fixedly mounted on the motor input shaft so that the rotation of the first drive gear and the rotation of the second drive gear are constrained by the motor input shaft; The third drive gear is fixedly mounted to the first input shaft so that rotation of the third drive gear is constrained by the first input shaft; The fourth drive gear is fixedly mounted to the second input shaft so 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 on 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 on 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 installed on the second output shaft.

7. The powertrain for a vehicle according to claim 6, wherein: a synchronizer configured to perform synchronization by using a synchronizer ring installed between the first and second synchronizers and the first driven gear; A dog clutch is installed between the first and second synchronizers and the second driven gear, in which the sleeves of the first and second synchronizers are directly meshed with the clutch gear of the second driven gear.

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

9. The powertrain for a vehicle according to claim 8, wherein: The clutch gear of the second driven gear and an end portion of the sleeve gear of the sleeve of the first and second synchronizers facing the clutch gear of the second driven gear form a flat shape facing each other.

10. The powertrain for a vehicle according to claim 6, wherein: The first and second synchronizers include: a first clutch gear connected to a first driven gear; a second clutch gear connected to a second driven gear; a hub fixed to the first output shaft; and A sleeve is slidably engaged to the hub and is configured to selectively restrict rotation of the first driven gear and the second driven gear according to movement of the sleeve of the first and second synchronizers.

11. The powertrain for a vehicle according to claim 6, wherein: The fourth and fifth synchronizers include: a first clutch gear connected to a fourth driven gear; a second clutch gear connected to a fifth driven gear; a hub fixed to the first output shaft; and A sleeve is slidably engaged to the hub and is configured to selectively restrict rotation of the fourth driven gear and rotation of the fifth driven gear according to movement of the sleeve of the fourth and fifth synchronizers.

12. The powertrain for a vehicle according to claim 6, wherein: The third and sixth synchronizers include: a first clutch gear connected to a third driven gear; a second clutch gear connected to a sixth driven gear; a hub fixed to the second output shaft; and A sleeve is slidably engaged to the hub and is configured to selectively restrict rotation of the third driven gear and the sixth driven gear according to movement of the sleeve of the third and sixth synchronizers.

13. The powertrain for a vehicle according to claim 5, wherein: A transmission ratio of the variable drive gear to the variable driven gear is smaller than a transmission ratio of the first drive gear to the first driven gear and a transmission ratio of the second drive gear to the second driven gear.

14. The powertrain for a vehicle according to claim 5, wherein: A clutch gear meshing with the central sleeve of the central synchronization unit is formed integrally with the third drive gear.

15. The powertrain for a vehicle according to claim 1, wherein The first clutch and the second clutch correspond to a double clutch formed in one clutch housing; The second input shaft is a hollow shaft surrounding the first input shaft.

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