WO2009097373A1

WO2009097373A1 - Six-speed dual powershift transmission

Info

Publication number: WO2009097373A1
Application number: PCT/US2009/032313
Authority: WO
Inventors: Masashi Ikezawa
Original assignee: Magna Powertrain of America Inc
Current assignee: Magna Powertrain of America Inc
Priority date: 2008-01-29
Filing date: 2009-01-29
Publication date: 2009-08-06
Anticipated expiration: 2010-07-29

Abstract

A transmission includes a main shaft, a first input shaft, a second input shaft and a first clutch to drivingly couple the main shaft and the first input shaft. A second clutch drivingly the couples the main shaft and the second input shaft. A first countershaft is driven by a first speed gearset associated with the first input shaft. A second countershaft is driven by a second speed gearset associated with the second input shaft. An output shaft is fixed for rotation with an output gear. A first countershaft gear is driven by the first countershaft. A second countershaft gear is driven by the second countershaft. The first and second countershaft gears are in meshed engagement with the output gear.

Description

SIX-SPEED DUAL POWERSHIFT TRANSMISSION BACKGROUND

[0001] The present disclosure generally relates to transmissions for automotive vehicles. More particularly, a three shaft, dual clutch transmission is disclosed.

[0002] A number of dual clutch transmissions have been designed to include concentric input shafts. Based on the arrangement of the input shafts, speed gears and various clutch components, odd numbered speed gears such as first, third and fifth may be connected to a first input shaft. A second input shaft is connected to the even numbered speed gears such as second, fourth, sixth and possibly reverse gear.

[0003] At least one known dual clutch transmission includes spaced apart speed gearsets each having two or more meshed gears for each forward drive ratio that is provided. Accordingly, a transmission having six forward drive ratios and one reverse drive ratio is equipped with six speed gearsets used in combination with a countershaft and at least one reverse gear. The resulting transmission may be relatively long. The weight of this transmission may also be greater than desired.

SUMMARY

[0004] The present disclosure provides a transmission including a main shaft, a first input shaft, a second input shaft and a first clutch to drivingly couple the main shaft and the first input shaft. A second clutch drivingly the couples the main shaft and the second input shaft. A first countershaft is driven by a first speed gearset associated with the first input shaft. A second countershaft is driven by a second speed gearset associated with the second input shaft. An output shaft is fixed for rotation with an output gear. A first countershaft gear is driven by the first countershaft. A second countershaft gear is driven by the second countershaft. The first and second countershaft gears are in meshed engagement with the output gear.

[0005] Additionally, a transmission includes a main shaft, a first input shaft, a second input shaft and a first clutch to drivingly couple the main shaft and the first input shaft. A second clutch drivingly couples the main shaft and the second input shaft. The transmission also includes first and second countershafts. First and third drive gears are driven by the first input shaft. Second, fourth and fifth drive gears are driven by the second input shaft. First and third driven gears are supported on the first countershaft. Second, fourth and fifth driven gears are supported on the second countershaft. The first, second, third, fourth and fifth drive gears are in meshed engagement with the corresponding first, second, third, fourth and fifth driven gears. The fifth driven gear is also in meshed engagement with the first driven gear.

[0006] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

[0007] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0008] Figure 1 is a schematic representing a six-speed dual clutch transmission depicting a power flow for a first gear drive ratio;

[0009] Figure 2 is a schematic end view of the transmission shown in Figure 1 ; [0010] Figure 3 is a schematic depicting a power flow when the transmission provides a second gear drive ratio;

[0011] Figure 4 is a schematic depicting a power flow when the transmission provides a third gear drive ratio

[0012] Figure 5 is a schematic depicting a power flow when the transmission provides a fourth gear drive ratio

[0013] Figure 6 is a schematic depicting a power flow when the transmission provides a fifth gear drive ratio

[0014] Figure 7 is a schematic depicting a power flow when the transmission provides a sixth gear drive ratio;

[0015] Figure 8 is a schematic depicting a power flow when the transmission provides a reverse gear ratio;

[0016] Figure 9 is a schematic representing another six-speed dual clutch transmission; and

[0017] Figure 10 is a schematic end view of the transmission shown in Figure 9.

DETAILED DESCRIPTION

[0018] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0019] Figures 1 and 2 are schematics representing a transmission 10 having a dual clutch 12 driven by a main shaft 14. During operation of dual clutch 12, torque may be transferred from main shaft 14 to one or both of a first input shaft 20 and a second input shaft 22. Second input shaft 22 is shaped as a tube having at least a portion of first input shaft 20 extending therethrough. Various speed gearsets are selectively operable to transfer torque from one of first input shaft 20 and second input shaft 22 to a first countershaft 24 and/or a second countershaft 26. Power is transferred to an output shaft 30 exiting transmission 10.

[0020] Dual clutch 12 includes a first clutch 32 and a second clutch 34. First clutch 32 is selectively operable to transfer torque from main shaft 14 to first input shaft 20. Similarly, second clutch 34 is selectively operable to transfer torque from main shaft 14 to second input shaft 22. First clutch 32 includes a first drum 36 fixed for rotation with main shaft 14. A set of outer first clutch plates 38 are fixed for rotation with and axially moveable relative to first drum 36. A set of inner first clutch plates 40 are fixed for rotation with first input shaft 20. Inner first clutch plates 40 are axially moveable relative to first input shaft 20 and interleaved with outer first clutch plates 38. An actuator (not shown) may be operable to compress outer first clutch plates 38 with inner first clutch plates 40 to transfer torque through first clutch 32.

[0021] Second clutch 34 includes a second drum 42 fixed for rotation with main shaft 14. A set of outer second clutch plates 44 are fixed for rotation with and axially moveable relative to second drum 42. A set of inner second clutch plates 46 are fixed for rotation with and axially moveable relative to a hub 48. Hub 48 is fixed for rotation with second input shaft 22. Inner second clutch plates 46 are interleaved with outer second clutch plates 44. Another actuator (not shown) or a portion of the previously introduced actuator may be operable to cause torque transfer through second clutch 34 by compressing outer second clutch plates 44 against inner second clutch plates 46. [0022] Second clutch 34 may encompass or partially envelop first clutch 32 to minimize the volume of space required to house dual clutch 12. In particular, an outer diameter of first drum 36 may be less than an inner diameter of hub 48 to allow first clutch 32 to nest within second clutch 34. Alternatively, if a greater torque capacity is required for first clutch 32, the outer diameter of first drum 36 may be increased to be equal or greater than the inner diameter of hub 48. As such, a modified nesting or axial adjacent arrangement of first clutch 32 and second clutch 34 may result.

[0023] A first speed gearset 50 transfers torque to first countershaft 24 and output shaft 30. First speed gearset 50 includes a first drive gear 52 fixed for rotation with first input shaft 20. A first driven gear 54 is supported for rotation on first countershaft 24. First drive gear 52 is in constant meshed engagement with first driven gear 54. A second speed gearset 56 includes a second drive gear 58 fixed for rotation with second input shaft 22. A second driven gear 60 is rotatably supported on second countershaft 26. Second drive gear 58 is in constant meshed engagement with second driven gear 60. A third speed gearset 62 includes a third drive gear 64 fixed for rotation with first input shaft 20. A third driven gear 66 is rotatably supported on first countershaft 24. Third drive gear 64 is in constant meshed engagement with third driven gear 66. A fourth speed gearset 68 includes a fourth drive gear 70 fixed for rotation with second input shaft 22. A fourth driven gear 72 is rotatably supported on second countershaft 26. Fourth drive gear 70 is in constant meshed engagement with fourth driven gear 72.

[0024] A fifth gear drive ratio is a direct drive or 1 :1 ratio. As such, a speed gearset is not required to provide the fifth gear drive ratio. A sixth speed gearset 76 includes a sixth drive gear 78 fixed for rotation with second input shaft 22. A sixth and reverse driven gear 80 is rotatably supported on second countershaft 26. Sixth drive gear 78 and sixth and reverse driven gear 80 are in constant meshed engagement with one another.

[0025] Additionally, an output gear 84 is fixed for rotation with output shaft 30. A first countershaft gear 86 is fixed for rotation with first countershaft 24. Output gear 84 and first countershaft 86 are in constant meshed engagement with one another. A second countershaft gear 88 is rotatably supported on second countershaft 26. Output gear 84 and second countershaft gear 88 are in constant meshed engagement with one another as well. Transmission 10 also includes first, second, third, fourth and fifth shifting mechanisms that will be described in greater detail hereinafter. The Figures depict first through fifth dog clutches 90, 92, 94, 96 and 98, respectively. However, it should be appreciated that any number of other mechanisms such as synchronizers or plate clutches may be used.

[0026] Transmission 10 is configured to provide six forward gear drive ratios and one reverse gear drive ratio through the use of the three shaft design previously described. Transmission 10 is relatively lightweight and compact. These features are at least partially accomplished through the implementation of sixth and reverse driven gear 80 simultaneously being in meshed engagement with sixth drive gear 78 and first driven gear 54. In similar fashion, output gear 84 is in constant meshed engagement with first countershaft gear 86 and second countershaft gear 88.

[0027] Figures 1 and 3-7 depict power flow through the various components of transmission 10 for each of the first through sixth forward drive gears as well as the reverse drive gear. Figure 1 diagrammatically depicts the flow of power through transmission 10 when a first gear drive ratio is being provided. Prior to transferring power at the first gear drive ratio, first dog clutch 90 is shifted to the left to drivingly interconnect first driven gear 54 and first countershaft 24. To achieve the desired power flow path, output shaft 30 is disconnected from first input shaft 20. As such, second dog clutch 92 is shifted to the left. The position of the remaining dog clutches does not determine the power flow path. However, to simplify operation of transmission 10, it is contemplated that third dog clutch 94 be controlled to drivingly engage second countershaft gear 88 with second countershaft 26 for all forward gear drive ratios and be disconnected only during reverse gear operation. First clutch 32 may now be actuated to transfer torque from main shaft 14 to first input shaft 20. Torque passes through first input shaft 20, first drive gear 52, first driven gear 54, first dog clutch 90, first countershaft gear 86 and output gear 84 to output shaft 30.

[0028] Figure 3 depicts the power flow achieved during the second drive ratio. Prior to transferring torque through transmission 10 at the second drive ratio, a sequential up-shift from the first drive ratio to the second drive ratio may be anticipated by pre-selecting the position of certain shift mechanisms. To pre-select a sequential up-shift from the first drive ratio to the second drive ratio, fourth dog clutch 96 is shifted to the left to drivingly engage second driven gear 60 with second countershaft 26. As previously mentioned, third dog clutch 94 is also actuated to shift to the right to drivingly interconnect second countershaft gear 88 with second countershaft 26.

[0029] Transmission 10 provides for power shifting between sequential drive ratio positions. To execute a power shift, a time overlap exists between disengagement of first clutch 32 and engagement of second clutch 34. The simultaneous actuation and de-actuation of the clutches within dual clutch 12 provides a smooth, uninterrupted flow of power to output shaft 30. Once first clutch 32 is completely disengaged, first dog clutch 90 may be shifted to a neutral position or further to the right to pre-select the third gear drive ratio.

[0030] Figure 4 depicts the flow of power through transmission 10 while the third gear drive ratio is provided. First dog clutch 90 is shifted to the right to drivingly engage third driven gear 66 with first countershaft 24. To shift from second gear to third gear, second clutch 34 is disengaged while first clutch 32 is engaged. Once a third gear drive ratio is established, power flows from main shaft 14 through first clutch 32, first input shaft 20, third drive gear 64, third driven gear 66, first dog clutch 90, first countershaft 24, first countershaft gear 86 and output gear 84 to output shaft 30.

[0031] Figure 5 shows the power flow through various components of transmission 10 during operation in the fourth gear drive ratio. Prior to transferring power through transmission 10 at the fourth gear drive ratio, a sequential up-shift may be anticipated. As such, fourth dog clutch 96 may be shifted to its right-most position to drivingly interconnect fourth driven gear 72 with second countershaft 26. First clutch 32 is disengaged while second clutch 34 is engaged. First dog clutch 90 may be shifted to its neutral position. After the third gear to fourth gear shift has been completed, power flows from main shaft 14 through second clutch 34, second input shaft 22, fourth drive gear 70, fourth driven gear 72, fourth dog clutch 96, second countershaft 26, third dog clutch 94, second countershaft gear 88 and output gear 84 to output shaft 30.

[0032] Figure 6 depicts the flow of power through transmission 10 for a fifth gear drive ratio. As previously mentioned, prior to beginning the fourth gear to fifth gear shift, first dog clutch 90 may be moved to its neutral position where neither first driven gear 54 nor third driven gear 66 are drivingly interconnected with first countershaft 24. A further pre-selection occurs by actuating second dog clutch 92 to drivingly interconnect first input shaft 20 with output shaft 30. To accomplish the fourth gear to fifth gear shift, second clutch 34 is disengaged while first clutch 32 is engaged. The fifth gear drive ratio is a direct drive, or 1:1, ratio. Accordingly, once the fifth drive gear is established, power flows from main shaft 14 through first clutch 32, first input shaft 20 and second dog clutch 92 to output shaft 30. Fourth dog clutch 96 may be returned to its neutral position. In addition, fifth dog clutch 98 may be pre-selected to its right-most position to drivingly interconnect sixth and reverse driven gear 80 with second countershaft 26 in anticipation for a sequential up-shift. At this time, first dog clutch 90 is moved to its neutral position if it is not already so positioned.

[0033] A fifth gear to sixth gear up-shift is achieved by simultaneously disengaging first clutch 32 and engaging second clutch 34. At substantially the same time, second dog clutch 92 is moved to its left-most position to disconnect first input shaft 20 from output shaft 30. Once the sixth gear drive ratio has been established, power is transferred from main shaft 14 through second clutch 34, sixth drive gear 78, sixth and reverse driven gear 80, fifth dog clutch 98, second countershaft 26, third dog clutch 94, second countershaft gear 88 and output gear 84 to output shaft 30 as shown in Figure 7.

[0034] Figure 8 shows transmission 10 being operated in a reverse gear. In reverse gear, fifth dog clutch 98 is moved to its right-most position to drivingly couple sixth and reverse driven gear 80 with second countershaft 26. Second dog clutch 92 remains in its left-most and disconnected position. First dog clutch 90 is moved to its left-most position to drivingly interconnect first driven gear 54 with first countershaft 24. Third dog clutch 94 is moved to its left-most position to disconnect second countershaft gear 88 from second countershaft 26. It should be appreciated that second clutch 34 may be used as a launching clutch for reverse gear during vehicle operation. Once the reverse gear has been established, power is transferred from main shaft 14 through second clutch 34, first input shaft 20, sixth drive gear 78, sixth and reverse driven gear 80, fifth dog clutch 98, first driven gear 54, first dog clutch 90, first countershaft 24, first countershaft gear 86 and output gear 84 to output shaft 30.

[0035] Figures 9 and 10 depict another six-speed dual clutch transmission identified at reference numeral 100. Transmission 100 is substantially similar to transmission 10. Accordingly, similar elements will be identified with like numerals having a prime suffix. Configuration of first clutch 32', second clutch 34', first input shaft 20', second input shaft 22', output shaft 30', first countershaft 24' and second countershaft 26' are substantially the same as previously described in relation to transmission 10. However, instead of placing dog clutches in communication with the driven gears of the second, fourth and sixth speed gearsets, gear shifting mechanisms are associated with the gears driven by second input shaft 22'.

[0036] A fourth dog clutch 102 is operable to selectively drivingly interconnect second drive gear 58' with second input shaft 22' to provide the second gear drive ratio. Fourth dog clutch 102 may be shifted to its right-most position to drivingly interconnect fourth drive gear 70' with second input shaft 22' to provide the fourth gear drive ratio. A fifth dog clutch 104 is operable to selectively drivingly interconnect sixth drive gear 78' with second input shaft 22' to provide the sixth gear drive ratio. First dog clutch 90' and second dog clutch 92' are substantially the same as described in relation to transmission 10. An alternate third dog clutch 94' is operable to drivingly interconnect second countershaft 26' with a stub shaft 106 having second countershaft gear 88' fixed thereto. It should be appreciated that transmission 100 may be equipped with the clutch design depicted as third dog clutch 94 in Figure 1 without departing from the scope of the present disclosure.

[0037] Transmission 100 provides six forward drive ratios and three reverse gear drive ratios. A first reverse gear drive ratio is accomplished by actuating fourth dog clutch 102 to drivingly interconnect second drive gear 58' with second input shaft 22'. First dog clutch 90' is also actuated to drivingly interconnect first driven gear 54' with first countershaft 24'.

[0038] A different reverse gear drive ratio may be provided by actuating fourth dog clutch 102 to drivingly couple fourth drive gear 70" with second input shaft 22' instead of engaging second drive gear 58'. Yet another reverse gear drive ratio may be obtained by moving fourth dog clutch 102 to a neutral or centered position and operating fifth dog clutch 104 to drivingly couple sixth drive gear 78' with second input shaft 22'.

[0039] Furthermore, the foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without departing from the spirit and scope of the disclosure as defined in the following claims.

Claims

CLAIMSWhat is claimed is:

1. A transmission comprising: a main shaft; a first input shaft; a second input shaft; a first clutch to drivingly couple the main shaft and the first input shaft; a second clutch to drivingly couple the main shaft and the second input shaft; a first countershaft driven by a first speed gearset associated with the first input shaft; a second countershaft driven by a second speed gearset associated with the second input shaft; an output shaft fixed for rotation with an output gear; a first countershaft gear being driven by the first countershaft; and a second countershaft gear being driven by the second countershaft, the first and second countershaft gears being in meshed engagement with the output gear.

2. The transmission of claim 1 wherein the first speed gearset includes a first drive gear driven by the first input shaft and a first driven gear supported by the first countershaft, the second speed gearset including a second drive gear driven by the second input shaft and a second driven gear supported by the second countershaft.

3. The transmission of claim 2 wherein the second drive gear and the first driven gear are in meshed engagement with the second driven gear.

4. The transmission of claim 1 wherein the output shaft is aligned with one of the first and second input shafts.

5. The transmission of claim 4 further including a clutch operable to drivingly interconnect the output shaft and one of the first and second input shafts to rotate at a common speed.

6. The transmission of claim 1 wherein the first clutch is at least partially enveloped by the second clutch.

7. The transmission of claim 1 wherein the second input shaft is hollow having the first input shaft positioned at least partially therein.

8. The transmission of claim 1 further including a clutch operable to drivingly interconnect one of the speed gears of the first speed gearset with the first countershaft.

9. The transmission of claim 1 further including a clutch operable to drivingly interconnect one of the speed gears of the second speed gearset with one of the second input shaft and the second countershaft.

10. The transmission of claim 1 wherein the first clutch and second clutch are at least partially engaged at the same time during a gear shift.

1 1. The transmission of claim 1 wherein the transmission provides six different forward drive ratios and a reverse drive ratio.

12. A transmission comprising: a main shaft; a first input shaft; a second input shaft; a first clutch to drivingly couple the main shaft and the first input shaft; a second clutch to drivingly couple the main shaft and the second input shaft; a first countershaft; a second countershaft; first and third drive gears driven by the first input shaft; second, fourth and fifth drive gears driven by the second input shaft; first and third driven gears supported on the first countershaft; and second, fourth, and fifth driven gears supported on the second countershaft, the first, second, third, fourth and fifth drive gears being in meshed engagement with the corresponding first, second, third, fourth and fifth driven gears, the fifth driven gear also being in meshed engagement with the first driven gear.

13. The transmission of claim 12 further including an output shaft, a first countershaft gear being driven by the first countershaft and a second countershaft gear being driven by the second countershaft, each of the first and second countershaft gears being in meshed engagement with an output gear fixed for rotation with the output shaft.

14. The transmission of claim 13 wherein the output shaft is aligned with one of the first and second input shafts.

15. The transmission of claim 13 further including a clutch operable to drivingly interconnect the output shaft and one of the first and second input shafts to rotate at a common speed.

16. The transmission of claim 12 wherein the first clutch is at least partially enveloped by the second clutch.

17. The transmission of claim 12 wherein the second input shaft is hollow having the first input shaft positioned at least partially therein.

18. The transmission of claim 12 further including a clutch selectively operable to individually drivingly interconnect the second driven gear and the fourth driven gear with the second countershaft.

19. The transmission of claim 12 further including a clutch selectively operable to individually drivingly interconnect the first driven gear and the third driven gear with the first countershaft.

20. The transmission of claim 12 wherein the transmission provides six different forward drive ratios and a reverse drive ratio.

21. The transmission of claim 20 wherein the transmission provides three reverse drive ratios.