BACKGROUND OF INVENTION

1. Field of Invention

[0001] The present invention relates generally to automatic transmissions and, more specifically, to a system and method for managing an upshift for shifting gears in an automatic transmission.

2. Description of the Related Art

[0002] Conventional vehicles typically include an engine having a rotational output that provides a rotational input into a transmission for a powertrain system of the vehicle. The transmission changes the rotational speed and torque generated by the output of the engine through a series of predetermined gearsets in a gearbox to transmit power to one or more wheels of the vehicle, whereby changing between the gearsets enables the vehicle to travel at different vehicle speeds for a given engine speed.

[0003] If the transmission is automatic, the transmission will normally include a plurality of automatically actuated clutches adapted to dynamically shift among variously available gear ratios of the gearsets without requiring driver intervention. The plurality of automatically actuated clutches, also called clutch modules, are incorporated within such transmissions to facilitate the automatic gear ratio changes. [0004] In the automatic transmission, anywhere from three to ten forward gear ratios may be available, not including a reverse gear. The various gearsets may include inner gears, intermediate gears such as planet or pinion gears supported by carriers, and outer ring gears. Specific transmission clutches may be associated with specific sets of the selectable gears within the gearsets of the automatic transmission to facilitate the desired gear ratio changes.

[0005] One of the clutch modules of the automatic transmission may have an inner race and an outer race disposed circumferentially about the inner race. One of the races, for example the inner race, may be drivingly rotatable in only one direction. The inner race may be selectively locked to the outer race via an engagement mechanism such as, but not limited to, a roller, a sprag, or a pawl, as examples. In the one direction, the inner race may be effective to directly transfer rotational motion from the engine to a driveline of the vehicle.

[0006] Within the above-described clutch module, the outer race may be fixed to an internal case or housing of an associated planetary member of the automatic transmission. Under such circumstances, in one configuration, the inner race may need to be adapted to drive in one rotational direction, but freewheel in the opposite direction, in a condition referred to as overrunning. This overrunning may be particularly desirable under certain operating states as, for example, when a vehicle is traveling downhill. In another configuration, such as when performing an upshift, the engagement mechanisms may be adapted for actively engaging in both rotational directions of the inner race, thus not allowing for the overrunning condition.

[0007] In the above-described transmissions, it is desirable to match or synchronize speeds between gears during shifting to allow smooth engagement of the gears. For example, in order to shift a discrete clutch or clutch module, the speed must be synchronized or, if the discrete clutch or clutch module has a one-way clutch function, the direction of rotation must change. In some applications, when shifting using a discrete clutch or clutch module where the direction of rotation does not change, the speed of the clutch module must be synchronized. Additionally, it is not possible to apply an inactive clutch element to synchronize the discrete clutch or clutch module. Thus, there is a need in the art to provide a system and method for managing an upshift for shifting gears in a transmission that synchronizes a discrete clutch or clutch module by reversing a torque direction from an input into the clutch module.

SUMMARY OF THE INVENTION

[0008] The present invention provides a system for managing an upshift for shifting gears in an automatic transmission of a vehicle. The system includes a transmission control unit adapted to communicate with an electronic control unit for an engine of the vehicle. The system also includes an automatic transmission having a housing, a plurality of gearsets disposed in the housing, and a multi-mode clutch module (MMCM) disposed between the housing and at least one gear of one of the gearsets and in communication with the transmission control unit. The transmission control unit is configured to receive a signal that an upshift of the gearsets begins, to begin closed loop speed control using an off-going clutch of another of the gearsets, and to synchronize speeds between the off-going clutch and the MMCM to complete the upshift from the another one of the gearsets to the one of the gearsets.

[0009] In addition, the present invention provides a method for managing an upshift for shifting gears in an automatic transmission of a vehicle. The method includes the steps of providing a transmission control unit in communication with an electronic control unit for an engine of the vehicle and providing an automatic transmission having a housing, a plurality of gearsets disposed in the housing, and a multi-mode clutch module (MMCM) disposed between the housing and at least one gear of one of the gearsets and in communication with the transmission control unit. The method also includes the steps of receiving, by the transmission control unit, a signal that an upshift of the gearsets begins, beginning, by the transmission control unit, closed loop speed control using an off-going clutch of another one of the gearsets, and synchronizing, by the transmission control unit, speeds between the off-going clutch and the MMCM to complete the upshift from the another one of the gearsets to the one of the gearsets.

[0010] One advantage of the present invention is that a system and method is provided for managing an upshift for shifting gears in an automatic transmission of a vehicle. Another advantage of the present invention is that the system and method matches or synchronizes speeds between gears during shifting to allow smooth engagement of the gears. Yet another advantage of the present invention is that the system and method utilizes a discrete clutch or clutch module using input torque intervention and off-going clutch control for managing an upshift. Still another advantage of the present invention is that the system and method manages an upshift by synchronizing a discrete clutch or multi-mode clutch module by reversing a torque direction from an input into the clutch or clutch module.

[0011] Other objects, features, and advantages of the present invention will be readily appreciated as the same becomes better understood after reading the subsequent description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic view of one embodiment of a system, according to the present invention, for managing an upshift for shifting gears in an automatic transmission. [0013] Figure 2 is a partial perspective view of a multi-mode clutch module (MMCM) used with the automatic transmission of the system of Figure 1.

[0014] Figure 3 is another partial perspective view of the MMCM of Figure 2.

[0015] Figure 4 is a partial fragmentary perspective view of the MMCM of Figure 2.

[0016] Figure 5 is a flowchart of a method, according to the present invention, for managing an upshift for shifting gears in an automatic transmission using the system of Figure 1.

[0017] Figure 6 is a diagrammatic view of the upshift of the gears of the automatic transmission using the method of Figure 5.

[0018] Figure 7 is a diagrammatic view of speed and torque dynamics during an upshift of the MMCM of Figure 2 using the method of Figure 5.

[0019] Figure 8 is a diagrammatic view of the pawl states of the MMCM of Figure 2 during the upshift of Figure 7.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Referring now to the figures, where like numerals are used to designate like structure unless otherwise indicated, a system 10, according to the present invention, for managing an upshift for shifting gears in a transmission, generally indicated at 12, in Figure 1 for a vehicle (not shown). The system 10 includes an engine 14 and the transmission 12 of the vehicle. In one embodiment, the engine 14 is a conventional internal combustion engine known in the art. In one embodiment, the transmission 12 is an automatic transmission. The engine 14 has a rotatable output that is an engine input 16 into the transmission 12. The transmission 12 translates the engine input 16 to a rotational output to transmit power to one or more wheels (not shown) of the vehicle. It should be appreciated that the transmission 12 of Figure 1 is of a type that may be employed in a conventional "transverse front wheel drive" powertrain system. It should also be appreciated that the engine 14 and/or transmission 12 could be of any suitable type to drive the vehicle, without departing from the scope of the present invention.

[0021] The transmission 12 includes a torque converter, generally indicated at 18, for translating torque from the engine input 16 of the engine 14 to an input shaft 20 of a transmission gearbox, generally indicated at 22. The gearbox 22 includes a transmission housing or case 23. The gearbox 22 also includes at least one output gear or shaft 24 to provide a rotational output of the transmission 12. The output of the output shaft 24 is passed to a differential assembly (not shown), which passes output drive to CV joints (not shown), in turn, to wheels of the vehicle. The gearbox 22 includes one or more gearsets, generally indicated at 26, disposed in the transmission housing 23 between the input shaft 20 and the output shaft 24. In one embodiment, the transmission 12 is a seven (7) speed automatic transmission. In one embodiment, the gearsets 26 includes a first gearset 26a for a first gear ratio, a second gearset 26b for a second gear ratio, a third gearset 26c for a third gear ratio, and a fourth gearset 26d for a fourth gear ratio of the transmission 12. It should be appreciated that, in this embodiment, the transmission 12 is a seven-speed automatic transmission, but in other embodiments, may have additional gearsets to provide additional ratios.

[0022] The transmission 12 also includes a plurality of clutches 28 such as a hydraulically-actuated clutch. The transmission 12 further includes at least one multi-mode clutch module (MMCM), generally indicated at 30, disposed between the transmission housing 23 and a gear 31 of the gearset 26b for a 6-7 upshift. It should be appreciated that an example of a MMCM is disclosed in U.S. Patent Application Publication No. 2015/0354640, the disclosure of which is hereby incorporated by reference in its entirety. [0023] Referring to Figures 2-4, in one embodiment, the MMCM 30 includes an exterior case or housing 32 coupled or grounded to the transmission housing 23 and an interior driven hub 34 coupled to the gear 31 and having axially oriented, circumferentially spaced cogs 36 provided on an outer periphery of the interior driven hub 34. The MMCM 30 also includes an inner race, generally indicated at 40, formed as two plates 40 A and 40B spaced along an axis "A- A", and adapted for supporting rotary movement of the plates 40A and 40B via the cogs 36. For this purpose, the plates 40A and 40B have circumferentially spaced detents 41 on their inside peripheries adapted to engage the cogs 36. The MMCM 30 also includes an outer race 42 disposed intermediately or between the two inner race plates 40A and 40B. The outer race 42 is rotationally fixed with respect to the interior of the exterior case or housing 32 and an actuator cam 44 is situated between the outer race 42 and the plate 40B of the inner race 40. The actuator cam 44 is adapted to be rotated over a small angle about the axis A-A between two circumferentially spaced positions. Within its interior periphery, the actuator cam 44 incorporates a strategically situated array of circumferentially spaced recesses, herein called slots 46, defined by and situated between projections, herein called cam teeth 48. The slots 46 and cam teeth 48 are adapted to interact with pawls, generally indicated at 50, circumferentially positioned about the axis A-A of the MMCM 30. It should be appreciated that the pawls 50 are situated so as to interact with both the inner race 40 and the outer race 42, and are arranged in sets of opposed pairs, 50A and 50B. It should also be appreciated that the actuator cam 44 is adapted to control interactions of the pawls 5 OA and 50B between the inner race 40 and the outer race 42.

[0024] The MMCM 30 further includes a hydraulic actuator 52 that engages an actuator coupling 54 to move an actuator tab 55 on the actuator cam 44 between the two angularly spaced positions. It should be appreciated that the actuator 52 ultimately controls the actuator tab 55 which, in turn, moves the actuator cam 44 between two distinct angular positions. It should also be appreciated that the positioning of the pawls 50A and 50B is directly controlled by the actuator cam 44 against forces of springs 54.

[0025] Referring now to Figure 4, it will be noted that the two inner race plates 40A and 40B, are adapted to rotate within the case or housing 32. Assuming the actuator cam 44 is in the first of its two specific angular positions, one set of the pawls, e.g. pawls 5 OB, will lock the inner race 40 (i.e., plates 40A and 40B) to the outer race 42, to drivingly rotate in one direction, for example counterclockwise. In the opposite rotational direction, e.g. clockwise, the pawls 50A will be unlocked so as to permit freewheeling of the inner race 40 relative to the outer race 42. Alternatively, when the actuator cam 44 is in the second of its two angular positions, both sets of pawls 50A and 50B, will lock the inner race 40 to the outer race 42 in either rotational direction when in a mode during which no overrunning is desirable. It should be appreciated that, in both configurations of the MMCM 30, the outer race 42 remains non-rotatable relative to the exterior case or housing 32. For accommodating interactions with the pawls 50A and 50B, the inner circumference of the outer race 42 contains circumferentially spaced notches 56, each defined by and situated between pairs of radially inwardly projecting cogs 58. It should be appreciated that the MMCM 30 will lock the inner race 40 to the outer race 42 to drivingly rotate in one direction and in the opposite rotational direction, the pawls 50 will be unlocked to permit free-wheeling of the inner race 40 relative to the outer race 42.

[0026] Referring again to Figure 1 , the system 10 also includes an electronic control unit (ECU) 60 to control the engine 14 of the vehicle. The ECU 60 communicates via a bus (not shown) between the engine 14 and other sensors (not shown) of the vehicle to track parameters such as engine speed, vehicle speed, TPS, etc. The system 10 may include an accelerator pedal sensor (not shown) communicating with the ECU 60 and positioned near an accelerator pedal (not shown) to sense a position of the accelerator pedal. It should be appreciated that the ECU 60 may communicate with the sensors via a bus, hard wires, or a combination thereof. It should also be appreciated that the ECU 60 may reduce the torque output or engine speed of the engine 14. It should further be appreciated that the ECU 60 is known in the art.

[0027] The system 10 further includes a transmission control unit (TCU) 62 in communication with the ECU 60 and the actuator 52 of the MMCM 30. The TCU 62 selects the next gear of the transmission 12 and the operating mode of the MMCM 30. It should be appreciated that the TCU 62 activates the actuator 52 to index the actuator cam 44 to block or unblock the pawls 50. It should be appreciated that the system 10 may include speed sensors (not shown) for the input shaft 20 and the output shaft that communicate with the TCU 62. It should also be appreciated that the TCU 62 is known in the art.

[0028] Referring to Figure 4, a method, according to the present invention, is shown for managing an upshift for shifting gears of the transmission 12 using the system 10 of Figure 1. In one embodiment, the method manages an upshift from 6 ^th gear to 7 ^th gear of the gearsets 26 of the transmission 12. In operation, the method starts in block 102 and manages an upshift of the applied gear 31 coupled to the MMCM 30 in block 104. For example, the TCU 62 will determine an accelerator pedal position and wheel speed from the ECU 60 to determine if a shift point between 6 ^th gear and 7 ^th gear is crossed. It should be appreciated that the method first starts with the operator or driver depressing the accelerator pedal to initiate an upshift of the transmission 12. It should also be appreciated that the TCU 62 includes a processor (not shown) configured to carry out or perform the method of Figure 4. [0029] The method includes the step of determining whether the engine state of the engine 14 is power-on in block 106. For example, the TCU 62 communicates with the ECU 60 to determine whether the engine 14 is producing positive torque by a difference in an engine speed being greater than a turbine speed of the torque converter 18. If so, the method includes the step of requesting engine torque reduction of the engine 14 in block 108. For example, the TCU 62 communicates with the ECU 60 by sending a signal to lower or reduce the amount of torque produced by the engine 14. The method includes the step of determining whether negative slip is produced by the transmission 12 in block 110. For example, the TCU 62 communicates with the ECU 60 to determine whether the transmission 12 is producing negative slip by a difference in the turbine speed of the torque converter 18 being greater than the engine speed of the engine 14. If not, the method includes the step of returning to block 108 to again request engine torque reduction of the engine 14. If so, the method includes the step of beginning closed loop speed control using an off-going clutch 28 in block 112. In addition, if the engine state is not power-on in block 106, the method directly advances to the step of beginning closed loop speed control using the off-going clutch 28 in block 112. It should be appreciated that the TCU 62 determines when the difference in speed between the engine speed and turbine speed occurs from positive to negative to begin closed loop speed control using the off-going clutch 28 for the upshift. It should also be appreciated that, since any positive torque increases speed, the TCU 62 keeps requesting a decrease in engine speed of the engine 14. It should further be appreciated that, if negative torque or slip occurs at the beginning of the method, no reduction in engine speed of the engine 14 is needed, and the TCU 62 begins closed loop speed control using the off-going clutch 28 for the upshift in block 112. [0030] To begin closed loop speed control using the off-going clutch 28 in block 112, the method includes the step of actuating the MMCM 30 to the one way clutch (OWC) position in block 114. For example, the TCU 62 will send a signal to the actuator 52 to cause the MMCM 30 to lock the inner race 40 to the outer race 42 to drivingly rotate in one direction. To cause this, the forward pawl 50A is loaded to the OWC position as illustrated in Figure 8. It should be appreciated that the MMCM 30 is in a freewheeling state in 6 ^th gear at a given speed and positive torque and the speed of the MMCM 30 is synchronized by reversing the torque direction of the input into the MMCM 30 during time segment "A" illustrated in Figure 7. It should also be appreciated that, during time segment A, speed feedback is used to control slip on the off-going clutch 28 to zero (0) by slipping the off-going clutch 28 to lower speed at a predetermined rate.

[0031] The method includes the step of determining whether the OWC position of the MMCM 30 has been reached in block 116. For example, the TCU 62 receives a signal from a position sensor (not shown) to determine if the OWC position of the MMCM 30 has been reached. If not, the method includes the step of returning to block 114 to again actuate the MMCM 30 to the OWC position as previously described. If so, the method includes the step of determining whether a speed of the MMCM 30 is synchronized in block 118. For example, the TCU 62 monitors the speed of the MMCM 30 and determines whether the speed of the MMCM 30 to be zero (0). If not, the method includes the step of continuing to determine whether the speed of the MMCM 30 is synchronized in block 118. For example, the TCU 62 keeps monitoring the speed of the MMCM 30 to determine if the speed of the MMCM 30 is zero (0). It should be appreciated that a ring gear (R) of the gearset 26b must be brought to zero RPM and a sun gear (S) of the gearset 26a must spin in the negative direction at 7 ^th gear synchronous speed. It should also be appreciated that positive engine torque from the engine 14 would accelerate the sun gear (S) of the gearset 26a in the positive direction (assuming the off-going clutch 28 allowed the sun gear (S) of the gearset 26a to slip) and negative engine torque is needed to accelerate a carrier gear (C) of the gearset 26d in the negative direction. It should further be appreciated, as the off-going clutch 28 slips and the sun gear (S) of the gearset 26a accelerates in the negative direction, the input speed to the MMCM 30 must drop to the 7 ^th gear ratio because the carrier gear (C) of the gearset 26d speed is relatively constant due to the vehicle inertia as illustrated in Figure 6.

[0032] If the speed of the MMCM 30 is synchronized, the method includes the step of unfilling the off-going clutch 28 in block 120. For example, the TCU 62 does not fill the off- going clutch 28 for the gearset 26a with fluid. The method includes the step of actuating the MMCM 30 to the lock position in block 122. For example, the TCU 62 will send a signal to the actuator 52 to cause the MMCM 30 to lock the inner race 40 to the outer race 42 to drivingly rotate in both directions. The method includes the step of determining whether the lock position of the MMCM 30 has been reached in block 124. For example, the TCU 62 receives a signal from the position sensor to determine if the lock position of the MMCM 30 has been reached. If not, the method includes the step of returning to block 122 to actuate the MMCM 30 to the lock position. If so, the method includes the step of determining whether the engine state of the engine 14 is power-on in block 126. For example, the TCU 62 communicates with the ECU 60 to determine whether the engine 14 is producing positive torque by the difference in the engine speed of the engine 14 being greater than the turbine speed of the torque converter 18. If so, the method includes the step of terminating the engine torque reduction request in block 128. For example, the TCU 62 terminates a signal to the ECU 60 requesting a decrease or reduction in engine speed of the engine 14. If not or after block 126, the method ends in block 130. [0033] Referring to Figures 7 and 8, during time segment A, the speed of the MMCM 30 is synchronized by reversing a torque direction of the input into the MMCM 30 and using speed feedback to control the slip on the off-going clutch 28. During time segment B, once the speed of the MMCM 30 is synchronized, the MMCM 30 is actuated to be locked in both directions. The off-going clutch 28 is then unfilled and the "coast" pawl 50A is holding the transmission 12 at the synchronous speed. During time segment C, the input torque sign is commanded back to the original direction at a reduced magnitude. This causes the "drive" pawl 50B to be engaged and system backlash to be removed. The input torque reduction is then removed and the upshift is complete.

[0034] Accordingly, the system 10 of the present invention allows for managing an upshift for shifting gears in the automatic transmission 12 of a vehicle. The system 10 of the present invention matches or synchronizes speeds between gears during shifting to allow smooth engagement of the gears in the transmission 12. The system 10 of the present invention utilizes a discrete clutch or MMCM 30 using input torque intervention and off-going clutch 28 control for managing an upshift. The system 10 of the present invention manages an upshift by synchronizing the MMCM 30 by reversing the torque direction from the input to the MMCM 30.

[0035] The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.

[0036] Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.