CROSS-REFERENCE TO RELATED APPLICATION S^

[0001] The present application claims priority to and all the benefits of U.S. Provisional Patent Application No. 62/212,231, filed on August 31, 2015, which is hereby expressly incorporated herein by reference in its entirety. BACKGROUND OF INVENTION

1. Field of Invention

[0002] The present invention relates generally to transmissions and, more specifically, to a system and method for electronic synchronization of speeds for shifting gears in manual, dual- clutch, and automated manual transmissions.

2. Description of the Related Art

[0003] Conventional vehicles typically include an engine having a rotational output that provides a rotational input into a transmission such as a manual 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.

[0004] When a vehicle operator or driver wants to change from one gear to another, the driver presses down on a clutch pedal of the vehicle. This operates a single clutch via a linkage, which disconnects the output of the engine from the input into the gearbox and interrupts power flow to the transmission. Then the vehicle operator uses a shift lever to select a new gear, a process that typically involves moving a toothed collar from one gear to another gear of a different size. In the gearbox, synchronizers match the gears before they are engaged to prevent grinding. Once the new gear is engaged, the driver releases the clutch pedal, which re-connects the output of the engine to the input of the gearbox to transmit power to the wheels.

[0005] Another type of transmission sometimes referred to in the art as a "dual clutch" transmission may be used for a vehicle. The dual-clutch transmission (DCT) uses two clutches, and the vehicle has no clutch pedal. Electronics and hydraulics control the clutches similar to a standard automatic transmission. In a DCT, however, the clutches operate independently. One clutch controls the odd gears (first, third, fifth and reverse), while the other controls the even gears (second, fourth and sixth), for example. Using this arrangement, the gears can be changed without interrupting the power flow from the engine to the transmission.

[0006] Yet another type of transmission sometimes referred to in the art as an "automated manual" transmission may be used for a vehicle. In general, the automated manual transmission (AMT) is a manual transmission with an electromechanical clutch actuator. The electronically controlled clutch actuator uses an electric motor to operate the clutch instead of a conventional clutch pedal and linkage operated setup. In the clutch actuator, rotary movement of the electric motor is transferred via a set of gears to a linear movement that is needed to engage and disengage the clutch via a pressure plate. The clutch is operated via a release lever and bearing which then helps to engage or disengage the gears in the transmission.

[0007] In the above-described transmissions, mechanical synchronizers are typically used to match or synchronize speeds between gears during shifting to allow smooth engagement of the gears. The synchronizer allows a collar and gear to synchronize their speeds while they are already in contact but before dog teeth engage. For example, a cone on one gear may fit into a cone-shaped depression on the collar. The gear and collar synchronize their speeds due to friction between the cone and collar. Then the outer part of the collar moves out of the way so that the gear can be engaged by the dog teeth. However, because of the pressure to free up space for additional gear ranges, it is desirable to eliminate the synchronizers to match or synchronize speeds for shifting gears in transmissions. Thus, there is a need in the art to provide a system and method for synchronizing speeds for shifting gears in a transmission that eliminates conventional synchronizers.

SUMMARY OF THE INVENTION [0008] The present invention provides a system for electronic synchronization of speeds for shifting gears in a transmission includes an electronic control module and an electronic synchronization module in communication with the electronic control module and adapted to cooperate with at least one input shaft of the transmission. The electronic control module is configured to receive a signal that a shift of the transmission begins, anticipating, by the electronic control module, a desired gear of the transmission; and synchronize, by the electronic synchronization module, speeds between the at least one input shaft of the transmission and the desired gear.

[0009] In addition, the present invention provides a method for electronic synchronization of speeds for shifting gears in a transmission of a vehicle including the steps of providing an electronic control module and providing an electronic synchronization module in communication with the electronic control module and adapted to cooperate with an input shaft of the transmission. The method also includes the steps of receiving, by the electronic control module, a signal that a shift of the transmission begins, anticipating, by the electronic control module, a desired gear of the transmission, and synchronizing, by the electronic synchronization module, speeds between the input shaft of the transmission and the desired gear.

[0010] One advantage of the present invention is that a system and method is provided for electronic synchronization of speeds for shifting gears in a transmission of a vehicle. Another advantage of the present invention is that the system and method provides electronic synchronization of speeds for shifting by equalizing an input speed with a speed of a desired or target gear to be engaged. Yet another advantage of the present invention is that the system and method utilizes an electric motor connected to one or more input shafts through a linkage such as a chain or a gear. Still another advantage of the present invention is that the system and method eliminates conventional synchronizers through the substitution of a mechanical clutch such as a dog clutch or multi-mode clutch in the transmission. A further another advantage of the present invention is that the system and method allows for shorter length manual transmissions, especially for a front wheel drive vehicle.

[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 a system, according to the present invention, for electronic synchronization of speeds for shifting gears in a transmission.

[0013] Figure 2 is a diagrammatic view of one embodiment of the system of Figure 1 for use with a four-speed manual transmission.

[0014] Figure 3 is a diagrammatic view of another embodiment of the system of Figure 1 for use with a dual clutch transmission.

[0015] Figure 4 is a flowchart of a method, according to the present invention, for electronic synchronization of speeds for shifting gears in a manual transmission using the system of Figure 1.

DETAILED DESCRIPTION OF THE INVENTION

[0016] 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 synchronization of speeds for shifting gears in a transmission, generally indicated at 12, in Figure 1 for a vehicle (not shown). The vehicle includes an engine 14 and the transmission 12. In one embodiment, the engine 14 is a conventional internal combustion engine known in the art The transmission 12 may be a manual transmission (MT), dual clutch transmission (OCT), or automated manual transmission (AMT). 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.

[0017] The transmission 12 includes a gearbox 18 having at least one input shaft 20 and at least one clutch 22 between the engine input 16 and the input shaft 20 of the gearbox 18. The gearbox 18 includes at least one output 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 the CV joints (not shown), in turn, to the wheels of the vehicle. The gearbox 18 also includes one or more gearsets, generally indicated at 26, between the input shaft 20 and the output shaft 24. 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 four-speed transmission, but in other embodiments, may have additional gearsets to provide additional ratios.

[0018] The system 10 also includes a shifter assembly 28 to allow an operator of the vehicle to shift gears of the gearsets 26 of the transmission 12 into a particular gear ratio. In one embodiment, the shifter assembly 28 has a shift lever 30 connected via a cable 32 to the gearbox 18 to shift the gearsets 26. It should be appreciated that movement of the shift lever 30 causes shift forks (not shown) in the transmission 12 to engage and push gear sleeves (not shown) into the positions desired by the driver to create the intended gear. It should also be appreciated that the shifter assembly 28 is known in the art.

[0019] The system 10 includes an electronic synchronization module, generally indicated at 34, to electronically synchronize the speed of the input shaft 20 of the transmission 12 with a speed of a desired or target gear of the gearsets 26 to be engaged. The electronic synchronization module 34 includes at least one electric motor (EM) 36 and at least one linkage 38 connected to an output of the electric motor 36 and the input shaft 20 of the transmission 12. In one embodiment, the linkage 38 may be a chain or gearset. It should be appreciated that the rotational output of the electric motor 36 is transferred via the linkage 38 to the input shaft 20 to increase or decrease the rotational speed of the input shaft 20 of the transmission 12.

[0020] The system 10 also includes an electronic control module (ECM) 40 connected to the electric motor 36 of the electronic synchronization module 34. The ECM 40 communicates via a bus between the electric motor 36 and other sensors (not shown) of the vehicle to track parameters such as engine speed, vehicle speed, TPS, etc. The system 10 includes a speed sensor 42 communicating with the ECM 40 and positioned near the linkage 38 to determine the speed on the linkage 38. The system 10 may include a clutch pedal sensor 44 communicating with the ECM 40 and positioned near a clutch pedal (not shown) to sense a position of the clutch pedal. The system 10 also includes a position sensor 46 communicating with the ECM 40 and positioned near the shifter assembly 28 to determine a position of the shift lever 30 of the shifter assembly 28. The system 10 further includes a block-out device 48 communicating with the ECM 40 and cooperating with the shifter assembly 28 to be activated by the ECM 40 to prevent the shift lever 30 from being shifted into a shift gate (not shown) of the shifter assembly 28. It should be appreciated that the ECM 40 may communicate with the sensors via a bus, hard wires, or a combination thereof. It should also be appreciated, that in one embodiment, the position sensor 46 and block-out device 48 are separately connected to the ECM 40. It should further be appreciated that the input shaft 20 and the output shaft 24 may be equipped with speed sensors 50.

[0021] Referring now to Figure 2, one embodiment of the system 10 of Figure 1 for use with a four-speed manual transmission 12 is shown. In this embodiment, like parts of the transmission 12 of Figure 1 have like reference numerals. In the manual transmission 12, the conventional synchronizers have been removed and replaced with mechanical clutches 52 such as a dog clutch or a Multi-Mode Clutch Module (MMCM). In this embodiment, the electric motor 36 is attached to the input shaft 20 through the linkage 38 with either a chain or gear drive. It should be appreciated that the system 10 operates similar to the system of Figure 1. It should also be appreciated that the MMCM may be similar to that disclosed in PCT Patent Application Publication No. WO 2014/120595, the entire disclosure of which is hereby expressly incorporated by reference.

[0022] Referring now to Figure 3, another embodiment of the system 10 of Figure 1 for use with a dual clutch transmission 12 is shown. In this embodiment, like parts of the transmission 12 of Figure 1 have like reference numerals. In the DCT transmission 12, the conventional synchronizers have been removed and replaced with mechanical clutches 52 such as a dog clutch or a MMCM In addition, there are two input shafts 20 that are each controlled separately by the electronic synchronization module 34 through a linkage 38 such as a gear or chain with an electric motor 36 attached and controlling each input shaft 20. In this embodiment, one electric motor 36 is attached to one input shaft 20 through one linkage 38 with either a chain or gear drive. It should be appreciated that, in this embodiment, the position sensor 46 and block-out device 48 for the shifter assembly 28 are eliminated. It should be appreciated that the system 10 operates similar to the system of Figure 1.

[0023] In yet another embodiment, the system 10 of Figure 1 may be used with an automated manual transmission (AMT) 12. In the AMT transmission 12, the conventional synchronizers may be removed and replaced with mechanical clutches 52 such as a dog clutch or a MMCM. In this embodiment, the electric motor 36 is attached to the input shaft 20 through the linkage 38 with either a chain or gear drive. It should be appreciated that, in this embodiment, the position sensor 46 and block-out device 48 for the shifter assembly 28 are also eliminated.

[0024] When the transmission 12 is either a DCT or AMT, the system 10 includes a transmission control unit (TCU) (not shown) and the selection of the next gear is conducted by the TCU in communication with the ECM It should be appreciated that, in this embodiment, the position sensor 46 and block-out device 48 for the shifter assembly 28 are also eliminated. It should be appreciated that the system 10 operates similar to the system 10 of Figure 1.

[0025] Referring to Figure 4, a method, according to the present invention, is shown for a shift event for shifting gears of the transmission 12 using the system 10 of Figure 1. To start or achieve electronic synchronization, the method includes the step of depressing the clutch pedal in block 56. The method first starts with the operator or driver depressing the clutch pedal and opening the clutch 22. Once the clutch 22 is open, the method also includes the step of beginning a shift event in block 58. The driver begins a shift event of the transmission 12 by moving the shift lever 30 into a shift gate of the shifter assembly 28. Next, the method includes the step of anticipating a desired or target gear for the shift event in block 60. Once the shift is initiated by the driver, the ECM 40 anticipates the desired or target gear. The method includes activating the block-out device 48 in block 62. The ECM 40 activates the block-out device 48 to block or prevent movement of the shift lever 30 to engage the desired gear until after the speeds are synchronized. The method includes the step of initiating synchronization in block 64. Once the block-out device 48 is activated, the ECM 40 initiates synchronization with the electronic synchronization module 34. During synchronization, the ECM 40 senses speeds to either speed up or slow down the electric motor 36 to correspondingly either speed up or slow down the input shaft 20 to match the speed of the input shaft 20 to the input speed for the desired or target gear 80 (Figure 3). The method includes the step of completing synchronization in block 66. Synchronization is complete once the speed of the input shaft 20 is matched to the input speed for the selected gear 80. The method includes the step of deactivating the block-out device in block 68. Once synchronization is complete, the ECM 40 deactivates the block-out device 48 to allow the driver to move the shift lever 30 to complete the engagement of the next or desired gear. The method includes the step of the driver completing the shift event in block 70. Once the ECM 40 deactivates the block-out device 48, the driver finishes moving the shift lever 30 and completes the shift event. The method includes the step of releasing the clutch pedal in block 72. Once the driver completes the shift event or finishes moving the shift lever 30, the driver releases the clutch pedal. The method then ends.

[0026] In the system 10, the ECM 40 selects the gear to synchronize. On the manual transmission 12 of FIG. 2, the position sensor 46 for the shifter assembly 28 communicates with the ECM 40. The block-out device 48 is used to prevent the operator or driver from engaging the desired gear until after the speed is synchronized. Once the speed is synchronized, the block- out device 48 moves and allows the driver to engage the desired gear via the shift lever 30. It should be appreciated that, in order to synchronize, the input speed of the input shaft 20 must be matched to the input speed for the selected gear 80.

[0027] During an upshift, the electric motor 36 must slow down the input shaft 20 in order to match the next gear ratio given. The speed of the input shaft 20 is controlled by the closed loop system 10, once the target speed is achieved on the input shaft 20, the block-out device 48 retracts and the driver completes the shifts. It should be appreciated that the shaft sleeve or mechanical clutch 52 can be engaged and the synchronization is complete.

[0028] During a downshift, the electric motor 36 must speed up the input shaft 20 in order to achieve the target speed. Once the target speed has been achieved, the block-out device 48 retracts and the driver engages the gear to compete the shift It should be appreciated that the operation is similar for the DCT transmission 12 and the AMT transmission 12 without the position sensor 46 and block-out device 48 for the shifter assembly 28.

[0029] Accordingly, the system 10 of the present invention allows for the elimination of conventional synchronizers within the gearbox 18 with the substitution of a mechanical clutch 52 such as a dog clutch or MMCM. The system 10 of the present invention reduces the overall package space and length and has less mass packaged into the transmission 12. Depending on the selected size of the electric motor 36, the system 10 of the present invention can include coasting regeneration which would allow for approximately 5-10% fuel efficiency improvement. Again, depending on the size of the electric motor 36, the system 10 of the present invention also has potential for engine start of the engine 14 with the use of the electric motor 36 and spinning the engine 14 through the clutch 22 and eliminating a starter. The system 10 of the present invention also could be packaged with an automated clutch to combine coasting stop-start. [0030] 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.

[0031] 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.