Drivetrain

Abstract

The transmission system 2 includes a first electric motor M1, a second electric motor M2, and a transmission system 2, the transmission system 2 including a first input shaft 3 drivingly coupled to the first electric motor M1, a second input shaft 5 drivingly coupled to the second electric motor M2, a first gear train 9 including a first gear element 11 rotatably mounted on the first input shaft 3 and a second gear element 13 rotatably mounted on the second input shaft 5, a second gear train 15 including a third gear element 17 rotatably mounted on the first input shaft 3 and a fourth gear element 19 rotatably mounted on the second input shaft 5, and a second gear train 16 including a third gear element 17 rotatably mounted on the first input shaft 3 and a fourth gear element 19 rotatably mounted on the second input shaft 5, and a second gear train 17 selectively locking the first gear element and the third gear element 11, 17 for rotation with the first input shaft 3 or locking the second gear element and the fourth gear element 19 together. and a gear selector assembly (37) configured to selectively lock the gear elements (11, 17; 13, 19) for rotation with the second input shaft (5), the gear selector assembly (37, 39) configured to lock each of its gear elements (11, 17; 13, 19) for rotation with its respective shaft (3;5) selectively from among the following operating modes: a mode in which the gear elements (11, 17; 13, 19) are locked for rotation with the shaft (3;5) in the forward torque direction and the reverse torque direction, a mode in which the gear elements (11, 17; 13, 19) are locked for rotation with the shaft (3;5) in the forward torque direction but not in the reverse torque direction; and a mode in which the gear elements (11, 17; 13, 19) are locked for rotation with the shaft (3;5) in the reverse torque direction but not in the forward torque direction.

Description

[Technical field]

[0001] The present invention relates to a drive train that is particularly suitable for use in electric vehicles, but may be used in other applications. [Background technology]

[0002] In a vehicle drive train with a conventional single clutch synchromesh transmission, it is necessary to disengage the transmission from the power source, such as the engine or motor, by operating the clutch before the current gear is deselected and the new gear is engaged. If power is not disengaged when attempting to engage the new gear, the synchromesh will not be able to engage the new gear element or will have to be forced to engage with the risk of damaging the transmission and causing a torque spike in the transmission. In most cases, this is because the speed of the engine is not matched to the speed of the new gear. In a motor vehicle, such as a car with a conventional gearbox and powered by an engine, the selection of a new gear ratio typically takes 0.5 to 1 second to complete. Thus, for example, when a higher gear is selected, a time delay allows the engine to reduce its speed [due to its own inertia] to more closely match the speed of the new gear before the clutch re-engages the engine and transmission, thereby reducing the likelihood of a torque spike occurring when power is re-applied.

[0003] Dual clutch transmission (DCT) systems have attempted to address this issue by using two clutches to seamlessly take over the transfer of torque when shifting between gears, but DCTs have several drawbacks, including the fact that they require the use of two friction clutches which are heavy and expensive, are complex to control, have parasitic losses, and are therefore not very efficient.

[0004] Another type of seamless transmission system is referred to as an instantaneous type transmission system. This family of transmission systems includes at least one selector assembly including a first set of engaging elements and a second set of engaging elements configured to selectively engage a drive formation on the respective gear elements associated therewith. The first set of engaging elements and the second set of engaging elements are configured to allow a new gear to be selected while the current gear is still engaged, and thus, in at least some shift types, a new gear can be selected under operation. This type of selector assembly has four modes of operation with respect to each gear element associated therewith: fully engaged (fully in gear) in both torque directions; disengaged in both torque directions (neutral); engaged in forward torque direction but disengaged in reverse torque direction; and disengaged in forward torque direction but engaged in reverse torque direction. It is the last two modes that allow a discrete ratio gearbox to have the ability to instantly shift up or down ratios under load without torque interruption.

[0005] Instantaneous transmission is described in WO 2004 / 099654, WO 2005 / 005868, WO 2005 / 005869, WO 2005 / 024261 and WO 2005 / 026570, WO 2006 / 095140, WO 2006 / 123128, WO 2006 / 123166, WO 2007 / 132209, WO 2008 / 0 No. 62192, WO 2008 / 096140, WO 2008 / 145979, WO 2009 / 06253, WO 2010 / 046654, WO 2010 / 046655, WO 2010 / 046652, WO 2012 / 164237, GB 2573592 and GB 2574291, the contents of which are incorporated by reference.

[0006] Some of the instantaneous transmissions mentioned above are primarily designed for vehicle drive trains including combustion engines. Thus, these transmissions are not necessarily optimized for electric vehicles. However, in transmission systems for electric vehicles with distinct ratios, it is desirable to have torque support during gear shifts, even if torque support is only available in some shift types and not in others, to prevent loss of power to the wheels during gear shifts. Furthermore, it is desirable to provide torque support using a relatively simple and compact transmission layout, for example by removing any unnecessary components. It is also desirable to have a transmission layout that provides flexibility in the relative size of the gear elements (and therefore the effective gear ratio), provides a relatively large number of effective gear ratios, and allows flexibility in the choice of electric motor used in the drive train. Also, some instantaneous transmission systems may suffer from shift shock (torque spike) when shifting between gears in at least some shift types. This is because in some gear shifts, a new gear can be selected while the current gear is still engaged, and there may be a speed difference between the currently engaged gear and the new gear. In some applications, such as motor sports vehicles, some shift shock may be acceptable, but in other applications, such as passenger vehicles, where more refined shifting is required, shift shock is undesirable.

[0007] EP 2529967 discloses a drive train suitable for use with an electric vehicle. The drive train includes a first electric motor and a second electric motor, and a transmission system. The transmission system includes a first primary shaft and a second primary shaft. The first electric motor is coupled to the first primary shaft, and the second electric motor is coupled to the second primary shaft. The first primary shaft and the second primary shaft are coaxially arranged. The transmission system includes four forward gears. The odd-numbered gears (first gear and third gear) are associated with the first primary shaft and thus with the first electric motor. The even-numbered gears (second gear and fourth gear) are associated with the second primary shaft and thus with the second motor. The drive train is configured such that drive forces from both the first motor and the second motor can be simultaneously provided to an output (differential gear). For example, in a first mode of operation, the first and second gears can be engaged simultaneously, with the first motor providing drive to the output through the first gear and the second motor providing drive to the output through the second gear. A torque support can be provided to the output during the shift so that there is no loss of drive during the gear shift. However, a significant limitation of this drive train is that the first motor can only provide drive to the output through the odd gears and the second motor can only provide drive to the output through the even gears. This limits the effectiveness and flexibility of the drive train. Also, the transmission is relatively large since the primary shafts are coaxially arranged and the gear train is arranged in a conventional manner along the axes of the first and second primary shafts. Also, the gear selector assembly used is a conventional synchromesh gear selector assembly. The synchronizing cones used in these devices are relatively large, which means that there is a relatively large separation between each pair of gears, and the synchronizers are relatively expensive. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2004 / 099654 [Patent Document 2] International Publication No. 2005 / 005868 [Patent Document 3] International Publication No. 2005 / 005869 [Patent Document 4] International Publication No. 2005 / 024261 [Patent Document 5] International Publication No. 2005 / 026570 [Patent Document 6] International Publication No. 2006 / 095140 [Patent Document 7] International Publication No. 2006 / 123128 [Patent Document 8] International Publication No. 2006 / 123166 [Patent Document 9] International Publication No. 2007 / 132209 [Patent Document 10] International Publication No. 2008 / 062192 [Patent Document 11] International Publication No. 2008 / 096140 [Patent Document 12] International Publication No. 2008 / 145979 [Patent Document 13] International Publication No. 2009 / 06253 [Patent Document 14] International Publication No. 2010 / 046654 [Patent Document 15] International Publication No. 2010 / 046655 [Patent Document 16] International Publication No. 2010 / 046652 [Patent Document 17] International Publication No. 2012 / 164237 [Patent Document 18] British Patent No. 2573592 [Patent Document 19] British Patent No. 2574291 [Patent Document 20] European Patent No. 2529967 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention seeks to alleviate at least one of the aforementioned problems, or at least provide an alternative drive train to existing drive trains. [Means for solving the problem]

[0010] According to one aspect, a drive train as claimed in claim 1 is provided. The drive train provides a relatively large number of operating states, which is greater than the number of gear trains provided. Typically, each operating state has a different effective gear ratio. The drive train is very flexible and may provide torque to the output from the first electric motor alone, from the second electric motor alone, or simultaneously by the first electric motor and the second electric motor. In at least one operating state, the drive train may provide torque to the output from both the first electric motor and the second electric motor via a common gear train. The drive train allows the first electric motor to selectively provide torque to the output via an odd gear in one operating state and an even gear in another operating state. The drive train allows the second electric motor to selectively provide torque to the output via an odd gear in one operating state and an even gear in another operating state. The drive train provides torque support during gear shifts, so that in at least one shift type, torque is always provided to the drive wheels during gear shifts. The drive train is compact and does not require an expensive and relatively large synchronizer type selector assembly. Use of a gear selector assembly of the claimed type helps synchronize the motor to the new gear in the gear shaft because the new gear element can be selected in a manner that locks it to rotate in one direction of rotation but not the other, which helps address torque reversals during shifts.

[0011] A drive train contains two motors, only one of which has the operational state to drive an output, so that in the unlikely event that one of the motors fails, the vehicle or other application can continue to operate using the remaining motor.

[0012] According to another aspect, there is provided a drive train as claimed in claim 2. The drive train has similar advantages as set out in claim 1. Additionally, with the claimed layout it is possible to fully synchronize the speed of one of the motors to the new gear before the shift occurs, so that the drive train shifts without any substantial shift shock (torque spike).

[0013] According to another aspect, a drive train is provided.

[0014] The drive train can include a first electric motor.

[0015] The drive train may include a second electric motor.

[0016] The drive train can include a transmission system.

[0017] The transmission system may include a first input shaft drivingly coupled to the first electric motor. The first input shaft may be directly coupled to the first electric motor, i.e., there is no gear or clutch between the output of the first electric motor and the first input shaft to transfer drive from the first electric motor to the first input shaft. For example, the first electric motor may have a first motor shaft, and the first motor shaft may be coupled to the first input shaft. The first motor shaft may be splined to the first input shaft.

[0018] The transmission system may include a second input shaft drivingly coupled to the second electric motor. The second input shaft may be directly coupled to the second electric motor, i.e., there is no gear or clutch between the output of the second electric motor and the second input shaft to transfer drive from the second electric motor to the second input shaft. For example, the second electric motor may have a second motor shaft, which may be coupled to the second input shaft. The second motor shaft may be splined to the second input shaft.

[0019] The transmission system may include a first gear train. The first gear train may include a first gear element mounted on a first input shaft. The first gear train may include a second gear element mounted on a second input shaft. In some embodiments, the first gear element may be rotatably mounted on the first input shaft. In some embodiments, the first gear element may be fixed for rotation with the first input shaft. In some embodiments, the second gear element may be rotatably mounted on the second input shaft. In some embodiments, the second gear element may be fixed for rotation with the second input shaft.

[0020] The transmission system can include a second gear train. The second gear train can include a third gear element mounted on the first input shaft. The second gear train can include a fourth gear element mounted on the second input shaft. In some embodiments, the third gear element can be rotatably mounted on the first input shaft. In some embodiments, the third gear element can be fixed for rotation with the first input shaft. In some embodiments, the fourth gear element can be rotatably mounted on the second input shaft. In some embodiments, the fourth gear element can be fixed for rotation with the second input shaft.

[0021] The transmission system can include an output shaft.

[0022] The transmission system can include a gear element mounted to the output shaft. In some embodiments, the gear element can be rotatably mounted to the output shaft. In some embodiments, the gear element can be fixed for rotation with the output shaft.

[0023] The transmission system may include a separate gear element mounted to the output shaft. In some embodiments, the separate gear element may be rotatably mounted to the output shaft. In some embodiments, the separate gear element may be fixed for rotation with the output shaft.

[0024] The transmission system can include a gear selector assembly. In some embodiments, the gear selector assembly can be configured to selectively lock the first gear element and the third gear element for rotation with the first input shaft. In some embodiments, the gear selector assembly can be configured to selectively lock the second gear element and the fourth gear element for rotation with the second input shaft. In some embodiments, the gear selector assembly can be configured to selectively lock the gear element and another gear element for rotation with the output shaft.

[0025] The gear selector assembly may be configured to lock each of its gear elements for rotation with its respective shaft selectively from among the following operating modes including a mode in which the gear element is locked for rotation with the shaft in both forward and reverse torque directions, a mode in which the gear element is locked for rotation with the shaft in the forward torque direction but not in the reverse torque direction; and a mode in which the gear element is locked for rotation with the shaft in the reverse torque direction but not in the forward torque direction.

[0026] In some embodiments, the gear selector assembly may be configured to lock the first gear element for rotation with the first input shaft selectively from among operating modes including a mode in which the first gear element is locked for rotation with the first input shaft in forward and reverse torque directions, a mode in which the first gear element is locked for rotation with the first input shaft in a forward torque direction but not in a reverse torque direction; and a mode in which the first gear element is locked for rotation with the first input shaft in a reverse torque direction but not in a forward torque direction.

[0027] In some embodiments, the gear selector assembly may be configured to lock the third gear element for rotation with the first input shaft selectively from among operating modes including a mode in which the third gear element is locked for rotation with the first input shaft in both forward and reverse torque directions, a mode in which the third gear element is locked for rotation with the first input shaft in the forward torque direction but not in the reverse torque direction; and a mode in which the third gear element is locked for rotation with the first input shaft in the reverse torque direction but not in the forward torque direction.

[0028] In some embodiments, the gear selector assembly may be configured to lock the second gear element for rotation with the second input shaft selectively from among operating modes including a mode in which the second gear element is locked for rotation with the second input shaft in both forward and reverse torque directions, a mode in which the second gear element is locked for rotation with the second input shaft in the forward torque direction but not in the reverse torque direction, and a mode in which the second gear element is locked for rotation with the second input shaft in the reverse torque direction but not in the forward torque direction.

[0029] In some embodiments, the gear selector assembly may be configured to lock the fourth gear element for rotation with the first input shaft selectively from among operating modes including a mode in which the fourth gear element is locked for rotation with the first input shaft in both forward and reverse torque directions, a mode in which the fourth gear element is locked for rotation with the second input shaft in the forward torque direction but not locked in the reverse torque direction, and a mode in which the fourth gear element is locked for rotation with the second input shaft in the reverse torque direction but not locked in the forward torque direction.

[0030] In some embodiments, the gear selector assembly may be configured to lock the gear element for rotation with the output shaft selectively from among operating modes including a mode in which the gear element is locked for rotation with the output shaft in both forward and reverse torque directions, a mode in which the gear element is locked for rotation with the output shaft in the forward torque direction but not in the reverse torque direction; and a mode in which the gear element is locked for rotation with the output shaft in the reverse torque direction but not in the forward torque direction.

[0031] In some embodiments, the gear selector assembly may be configured to lock the other gear element for rotation with the output shaft selectively from among operating modes including a mode in which the other gear element is locked for rotation with the output shaft in both forward and reverse torque directions, a mode in which the other gear element is locked for rotation with the output shaft in the forward torque direction but not in the reverse torque direction; and a mode in which the other gear element is locked for rotation with the output shaft in the reverse torque direction but not in the forward torque direction.

[0032] The transmission system may include a further gear selector assembly. The further gear selector assembly may be configured to selectively lock a pair of gear elements to rotate with their respective shafts. Typically, the further gear selector assembly selectively locks a gear element to rotate with their respective shafts other than those selectable by the gear selector assembly described above. For example, the gear selector assembly may be configured to selectively lock one of the first gear element and the third gear element to rotate with the first input shaft; the second gear element and the fourth gear element to rotate with the second input shaft; and the gear element and another gear element to rotate with the output shaft. The further gear selector assembly may be configured to selectively lock another one of the first gear element and the third gear element to rotate with the first input shaft; the second gear element and the fourth gear element to rotate with the second input shaft; and the gear element and another gear element to rotate with the output shaft.

[0033] Another gear selector assembly may be configured to lock each of its gear elements for rotation with its respective shaft selectively from among the following operating modes: a mode in which the gear element is locked for rotation with the shaft in both forward and reverse torque directions, a mode in which the gear element is locked for rotation with the shaft in the forward torque direction but not in the reverse torque direction; and a mode in which the gear element is locked for rotation with the shaft in the reverse torque direction but not in the forward torque direction.

[0034] In some embodiments, another gear selector assembly may be configured to lock the first gear element for rotation with the first input shaft selectively from among operating modes including a mode in which the first gear element is locked for rotation with the first input shaft in forward and reverse torque directions, a mode in which the first gear element is locked for rotation with the first input shaft in a forward torque direction but not in a reverse torque direction, and a mode in which the first gear element is locked for rotation with the first input shaft in a reverse torque direction but not in a forward torque direction.

[0035] In some embodiments, another gear selector assembly may be configured to lock the third gear element for rotation with the first input shaft selectively from among operating modes including a mode in which the third gear element is locked for rotation with the first input shaft in both forward and reverse torque directions, a mode in which the third gear element is locked for rotation with the first input shaft in the forward torque direction but not in the reverse torque direction, and a mode in which the third gear element is locked for rotation with the first input shaft in the reverse torque direction but not in the forward torque direction.

[0036] In some embodiments, another gear selector assembly may be configured to lock the second gear element for rotation with the second input shaft selectively from among operating modes including a mode in which the second gear element is locked for rotation with the second input shaft in both forward and reverse torque directions, a mode in which the second gear element is locked for rotation with the second input shaft in the forward torque direction but not in the reverse torque direction, and a mode in which the second gear element is locked for rotation with the second input shaft in the reverse torque direction but not in the forward torque direction.

[0037] In some embodiments, another gear selector assembly may be configured to lock the fourth gear element for rotation with the second input shaft selectively from among operating modes including a mode in which the fourth gear element is locked for rotation with the second input shaft in both forward and reverse torque directions, a mode in which the fourth gear element is locked for rotation with the second input shaft in the forward torque direction but not in the reverse torque direction; and a mode in which the fourth gear element is locked for rotation with the second input shaft in the reverse torque direction but not in the forward torque direction.

[0038] In some embodiments, the separate gear selector assembly may be configured to lock the gear element for rotation with the output shaft selectively from operating modes including a mode in which the gear element is locked for rotation with the output shaft in both forward and reverse torque directions, a mode in which the gear element is locked for rotation with the output shaft in the forward torque direction but not in the reverse torque direction; and a mode in which the gear element is locked for rotation with the output shaft in the reverse torque direction but not in the forward torque direction.

[0039] In some embodiments, the another gear selector assembly may be configured to lock the another gear element for rotation with the output shaft selectively from among operating modes including a mode in which the another gear element is locked for rotation with the output shaft in both forward and reverse torque directions, a mode in which the another gear element is locked for rotation with the output shaft in the forward torque direction but not in the reverse torque direction; and a mode in which the another gear element is locked for rotation with the output shaft in the reverse torque direction but not in the forward torque direction.

[0040] In some embodiments, the first gear element meshes with a third gear element.

[0041] In some embodiments, the second gear element meshes with a fourth gear element.

[0042] Torque from the second electric motor can be transferred to at least one gear element mounted on the first input shaft. For example, torque can be transferred from the second electric motor to the first gear element via the second gear element. Torque can be transferred from the second electric motor to the third gear element via the fourth gear element.

[0043] In some embodiments, the first gear train may include a gear element mounted on the output shaft. The first gear element may mesh with a gear element mounted on the output member. When the first gear element meshes with the second gear element and the first gear element meshes with the gear element mounted on the output member, this provides a very simple and compact transmission layout. Torque may be selectively provided from the first electric motor to the output member via the first gear train. Torque may be selectively provided from the second electric motor to the output member via the first gear train.

[0044] The transmission system may include a third gear train. The third gear train may include a fifth gear element rotatably mounted to the first input shaft. The third gear train may include a gear element mounted to the output member. Torque may be selectively provided from the first electric motor to the output member via the third gear train. Torque may be selectively provided from the second electric motor to the output member via the first gear train and the third gear train. Having a first gear train connecting the first input shaft and the second input shaft and a third gear train connecting the first input shaft to the output member provides greater flexibility in determining the relative power ratings of the first electric motor and the second electric motor, and greater flexibility in determining the relative sizes of the gear elements, and therefore the ratios therebetween. This allows the motors and / or gearing to be selected for a particular purpose, such as hard acceleration, low speed, starting, or cruising at high speed.

[0045] The first gear element and the fifth gear element may be fixedly mounted to the first sleeve. The first sleeve may be rotatably mounted to the first input shaft. The gear selector assembly may be configured to selectively lock the first sleeve for rotation with the first input shaft. Because the first gear element and the fifth gear element are fixed for rotation with the first sleeve, selectively locking the first sleeve for rotation with the first input shaft also selectively locks the first gear element and the fifth gear element for rotation with the first input shaft.

[0046] The gear selector assembly may be configured to selectively lock the first sleeve for rotation with the first input shaft from among operating modes including a mode in which the first sleeve is locked for rotation with the first input shaft in both forward and reverse torque directions, a mode in which the first sleeve is locked for rotation with the first input shaft in a forward torque direction but not in a reverse torque direction, and a mode in which the first sleeve is locked for rotation with the first input shaft in a reverse torque direction but not in a forward torque direction. Because the first gear element and the fifth gear element are locked for rotation with the first sleeve, the selection modes for the gear selector assembly also apply to the first gear element and the fifth gear element.

[0047] In some embodiments, the second gear train may include another gear element mounted on the output shaft. The third gear element may mesh with another gear element mounted on the output member. In embodiments where the third gear element meshes with a fourth gear element, and the third gear element meshes with another gear element mounted on the output member, this provides a very simple and compact transmission layout. Torque may be selectively provided from the first electric motor to the output member via the second gear train. Torque may be selectively provided from the second electric motor to the output member via the second gear train.

[0048] The transmission system may include a fourth gear train. The fourth gear train may include a sixth gear element rotatably mounted on the first input shaft. The fourth gear train may include another gear element mounted on the output member. Torque may be selectively provided from the first electric motor to the output member via the fourth gear train. Torque may be selectively provided from the second electric motor to the output member via the second gear train and the fourth gear train. Having the second gear train and the fourth gear train provides greater flexibility in determining the relative power ratings of the first electric motor and the second electric motor, and greater flexibility in determining the relative sizes of the gear elements, and therefore the ratios between them. This allows the motors and / or gearing to be selected for a particular purpose, such as hard acceleration, low speed, starting, or cruising at high speed.

[0049] The third gear element and the sixth gear element may be fixedly mounted to the second sleeve. The second sleeve may be rotatably mounted to the first input shaft. The gear selector assembly may be configured to selectively lock the second sleeve for rotation with the first input shaft. Because the third gear element and the sixth gear element are fixed for rotation with the second sleeve, selectively locking the second sleeve for rotation with the first input shaft also selectively locks the third gear element and the sixth gear element for rotation with the first input shaft.

[0050] The gear selector assembly may be configured to selectively lock the second sleeve for rotation with the first input shaft from among operating modes including a mode in which the second sleeve is locked for rotation with the first input shaft in both forward and reverse torque directions, a mode in which the second sleeve is locked for rotation with the first input shaft in the forward torque direction but not in the reverse torque direction, and a mode in which the second sleeve is locked for rotation with the first input shaft in the reverse torque direction but not in the forward torque direction. Because the third gear element and the sixth gear element are locked for rotation with the second sleeve, the selection modes for the gear selector assembly also apply to the third gear element and the sixth gear element.

[0051] The drive train can have at least one operating state in which torque is provided from the first electric motor through the first gear train to the output member. An operating state is a normal operating condition of the transmission and is not a gear shift. A gear shift is a condition in which the transmission is changing from one operating state to another.

[0052] The drive train can have at least one operating state in which torque is provided from the first electric motor through the second gear train to the output member.

[0053] The drive train can have at least one operating state in which torque is provided from the first electric motor through the third gear train to the output member.

[0054] The drive train can have at least one operating state in which torque is provided from the first electric motor through the fourth gear train to the output member.

[0055] The drive train can have at least one operating state in which torque is provided from the second electric motor through the first gear train to the output member.

[0056] The drive train can have at least one operating state in which torque is provided from the second electric motor through the second gear train to the output member.

[0057] The drive train can have at least one operating state in which torque is provided from the second electric motor through the third gear train to the output member. Torque may be provided from the second electric motor simultaneously through the first gear train and the third gear train to the output member.

[0058] The drive train can have at least one operating state in which torque is provided from the second electric motor through the fourth gear train to the output member. Torque may be provided from the second electric motor simultaneously through the second gear train and the fourth gear train to the output member.

[0059] The drive train can have at least one operating state in which torque is provided by the first electric motor alone to an output member. The drive train can have a plurality of operating states in which torque is provided by the first motor alone to an output member. For example, the drive train can include two operating states in which torque is provided by the first motor alone to an output member.

[0060] The drive train can have at least one operating state in which torque is provided by the second electric motor alone to an output member. The drive train can have a plurality of operating states in which torque is provided by the second motor alone to an output member. For example, the drive train can include two operating states in which torque is provided by the second motor alone to an output member.

[0061] The drive train can have at least one operating state in which torque is simultaneously provided by the first electric motor and the second electric motor to the output member. The drive train can have a plurality of operating states in which torque is simultaneously provided by the first electric motor and the second electric motor to the output member. For example, the drive train can have four operating states in which torque is simultaneously provided by the first electric motor and the second electric motor to the output member.

[0062] The drive train can have at least one operating state in which torque is provided to the output member by the first electric motor and the second electric motor simultaneously through different gear trains. For example, torque may be provided to the output member by the first electric motor and the second electric motor simultaneously, with the first electric motor providing torque through one of the first gear train and the second gear train and the second electric motor providing torque through the other of the first gear train and the second gear train. Torque may be provided to the output member by the first electric motor and the second electric motor simultaneously, with the first electric motor providing torque through one of the third gear train and the fourth gear train and the second electric motor providing torque through the other of the third gear train and the fourth gear train.

[0063] The drive train may have at least one operating state in which torque is provided to the output member by the first electric motor and the second electric motor simultaneously via a common gear train. The drive train may be configured such that in a plurality of operating states, torque may be provided to the output member by the first electric motor and the second electric motor simultaneously via a common gear train. The common gear train may be different in each operating state. For example, torque may be provided to the output member by the first electric motor and the second electric motor simultaneously, the first electric motor and the second electric motor providing torque to the output member via the first gear train. Torque may be provided to the output member by the first electric motor and the second electric motor simultaneously, the first electric motor and the second electric motor providing torque to the output member via the second gear train. Torque may be provided to the output member by the first electric motor and the second electric motor simultaneously, the first electric motor and the second electric motor providing torque to the output member via a third gear train. Torque may be simultaneously provided by the first electric motor and the second electric motor to the output member, the first electric motor and the second electric motor providing torque to the output member via a fourth gear train.

[0064] The drive train may be configured such that the first electric motor provides torque to the output member through an odd-numbered gear in one operating state and through an even-numbered gear in another operating state. For example, in a vehicle embodiment having a first gear, a second gear, a third gear, a fourth gear, etc., the first electric motor may provide torque to the output member through an odd-numbered gear, such as the first gear or the third gear, in one operating state and through an even-numbered gear, such as the second gear or the fourth gear, in another operating state.

[0065] The drive train may be configured such that the second electric motor provides torque to the output member through an odd-numbered gear in one operating condition and through an even-numbered gear in another operating condition.

[0066] The drive train may be configured to provide torque support to the output member during gear shifting, such that there is no torque discontinuity during gear shifting for at least one shift type. The drive train provides torque support during power-on upshifts and power-on downshifts. Battery regeneration may occur during power-off upshifts and power-off downshifts, where overrun occurs.

[0067] During a gear shift, the speed of one of the first electric motor and the second electric motor may be synchronized with the speed of the new gear. This may be true for at least one shift type. This helps minimize torque spikes while the new gear is engaged by each gear selector assembly. For example, the speed of the first electric motor may be synchronized with the rotational speed of one of the first sleeve and the second sleeve. The speed of the second electric motor may be synchronized with one of the third sleeve and the fourth sleeve. The synchronization of the speeds of the electric motors occurs before each gear selector assembly engages the new gear. For example, the speed of the first electric motor may be synchronized with the speed of one of the first sleeve and the second sleeve before the gear selector assembly engages that sleeve. The speed of the second electric motor may be synchronized with the speed of one of the third sleeve and the fourth sleeve before another gear selector assembly engages that sleeve. The electronic controller may regulate the speeds of the electric motors. Use of a gear selector assembly of the claimed type aids in synchronizing the motor with a new gear in the gear shaft because the new gear element can be selected in a manner that locks it to rotate in one direction of rotation but not the other, which helps to deal with torque reversals or spikes during shifting.

[0068] During a gear shift, the torque output of one of the first electric motor and the second electric motor may be reduced, preferably to zero or near zero, which may be the case for at least one shift type.

[0069] During a gear shift, the torque output of the other of the first motor and the second motor may increase. This may be true for at least one shift type. This may occur, for example, when shifting from one operating state in which both the first electric motor and the second electric motor provide torque to an output member to another operating state in which both the first electric motor and the second electric motor provide torque to an output member. The momentary increase in the torque output of one motor compensates for the loss of torque from the other motor.

[0070] At least one of the gear selector assembly and the further gear selector assembly may include a first set of engaging members and a second set of engaging members. The first set of engaging members and the second set of engaging members may be configured to move independently of one another. The first set of engaging members and the second set of engaging members may be configured to move into and out of engagement with drive arrangements associated with each gear element, such as the first gear element and the third gear element, the second gear element and the fourth gear element, or a gear element and another gear element. The drive arrangements may be formed directly on the gear elements. The drive arrangements may be formed on components associated with the gear elements, such as a sleeve.

[0071] The first set of engaging members and the second set of engaging members may be configured such that when the first set of engaging members and the second set of engaging members select the first gear element and a braking force is transmitted, the first set of engaging members drivingly engages with the drive arrangement associated with the first gear element and the second set of engaging members is in an unloaded state, and when a driving force is transmitted, the second set of engaging members drivingly engages with the drive arrangement associated with the first gear element and the first set of engaging members is in an unloaded state.

[0072] The first set of engaging members and the second set of engaging members may be configured such that when the first set of engaging members and the second set of engaging members select the third gear element and a drive force can be transmitted, the first set of engaging members drivingly engage with the drive arrangement associated with the third gear element and the second set of engaging members are in an unloaded state, and when a braking force is transmitted, the second set of engaging members drivingly engage with the drive arrangement associated with the third gear element and the first set of engaging members are then in an unloaded state.

[0073] The first set of engaging members and the second set of engaging members may be configured such that when the first set of engaging members and the second set of engaging members select the second gear element and a braking force is transmitted, the first set of engaging members drivingly engage with a drive arrangement associated with the second gear element and the second set of engaging members are in an unloaded state, and when a drive force is transmitted, the second set of engaging members drivingly engage with a drive arrangement associated with the second gear element and the first set of engaging members are in an unloaded state.

[0074] The first set of engaging members and the second set of engaging members may be configured such that when the first set of engaging members and the second set of engaging members select the fourth gear element and a drive force is transmitted, the first set of engaging members drivingly engages with the drive arrangement associated with the fourth gear element and the second set of engaging members is in an unloaded state, and when a braking force is transmitted, the second set of engaging members drivingly engages with the drive arrangement associated with the fourth gear element and the first set of engaging members is in an unloaded state.

[0075] The first set of engaging members and the second set of engaging members may be configured such that the first set of engaging members and the second set of engaging members select a gear element mounted on the output shaft, such that when a braking force is transmitted, the first set of engaging members drivingly engages a drive arrangement associated with the gear element and the second set of engaging members is in an unloaded state, and when a drive force is transmitted, the second set of engaging members drivingly engages a drive arrangement associated with the gear element and the first set of engaging members is in an unloaded state.

[0076] The first set of engaging members and the second set of engaging members may be configured such that the first set of engaging members and the second set of engaging members select another gear element mounted on the output shaft, and when a drive force is transmitted, the first set of engaging members drivingly engages a drive arrangement associated with the other gear element and the second set of engaging members is in an unloaded state, and when a braking force is transmitted, the second set of engaging members drivingly engages a drive arrangement associated with the other gear element and the first set of engaging members is in an unloaded state.

[0077] The maximum power rating of the first electric motor may be different from the maximum power rating of the second electric motor. Different types of motors may be used for the first and second electric motors, such that one motor is suitable for a first set of operating conditions and the second motor is suitable for a second set of operating conditions.

[0078] The first input shaft and the second input shaft may be parallel. The first input shaft and the second input shaft may be non-coaxial. The longitudinal axes of the first input shaft and the second input shaft are spaced sufficiently from each other to accommodate a gear train extending from the first input shaft to the second input shaft.

[0079] According to another aspect, a vehicle includes a first electric motor, a second electric motor, and a transmission system, the transmission system including a first input shaft drivingly coupled to the first electric motor, a second input shaft drivingly coupled to the second electric motor, a first gear train that may include a first gear element rotatably mounted on the first input shaft and a second gear element rotatably mounted on the second input shaft, a second gear train that may include a third gear element rotatably mounted on the first input shaft and a fourth gear element rotatably mounted on the second input shaft, a gear selector assembly configured to selectively lock the first gear element and the third gear element for rotation with the first input shaft, and a gear selector assembly configured to selectively lock the second gear element and the fourth gear element for rotation with the second input shaft. and another gear selector assembly configured to lock the first gear element for rotation with the first input shaft selectively from operational modes including a mode in which the first gear element is locked for rotation with the first input shaft in forward and reverse torque directions, a mode in which the first gear element is locked for rotation with the first input shaft in a forward torque direction, but not in a reverse torque direction; and a mode in which the first gear element is locked for rotation with the first input shaft in a reverse torque direction, but not in a forward torque direction; and a mode in which the first gear element is locked for rotation with the first input shaft in a reverse torque direction, but not in a forward torque direction; andand a mode in which the third gear element is locked for rotation with the first input shaft in a reverse torque direction, but not locked in a forward torque direction; and / or a separate gear selector assembly may be configured to lock the third gear element for rotation with the first input shaft selectively from modes of operation including a mode in which the second gear element is locked for rotation with the second input shaft in both forward and reverse torque directions, a mode in which the second gear element is locked for rotation with the second input shaft in a forward torque direction, but not locked in a reverse torque direction; and a mode in which the second gear element is locked for rotation with the second input shaft in a reverse torque direction, but not locked in a forward torque direction. a second gear element configured to selectively lock the second gear element for rotation with the second input shaft from a first gear selector assembly configured to selectively lock the fourth gear element for rotation with the first input shaft from a second gear selector assembly configured to selectively lock the fourth gear element for rotation with the second input shaft from a second gear selector assembly configured to selectively lock the fourth gear element for rotation with the first input shaft from a second gear selector assembly configured to selectively lock the fourth gear element for rotation with the second input shaft in a forward torque direction and a reverse torque direction; a mode in which the fourth gear element is locked for rotation with the second input shaft in a forward torque direction but not in a reverse torque direction; and a mode in which the fourth gear element is locked for rotation with the second input shaft in a reverse torque direction but not in a forward torque direction.

[0080] According to another aspect, a powertrain includes a first electric motor, a second electric motor, and a transmission system, the transmission system including a first input shaft drivingly coupled to the first electric motor, a second input shaft drivingly coupled to the second electric motor, an output shaft, a first gear train including a first gear element rotatably mounted on the first input shaft, a second gear element fixed for rotation with the second input shaft, and a gear element rotatably mounted on the output shaft, a second gear train including a third gear element rotatably mounted on the first input shaft, a fourth gear element fixed for rotation with the second input shaft, and another gear element rotatably mounted on the output shaft, and a third gear element rotatably mounted on the first input shaft, a fourth gear element fixed for rotation with the second input shaft, and another gear element rotatably mounted on the output shaft. A drive train is provided that includes a gear selector assembly configured to selectively lock a gear element for rotation with the shaft, and another gear selector assembly configured to selectively lock a gear element and another gear element for rotation with an output shaft, wherein at least one of the gear selector assemblies is configured to lock each of its respective gear elements for rotation with its respective shaft selectively from among the following operating modes: a mode in which the gear element is locked for rotation with the shaft in forward torque and reverse torque directions, a mode in which the gear element is locked for rotation with the shaft in the forward torque direction, but not in the reverse torque direction; and a mode in which the gear element is locked for rotation with the shaft in the reverse torque direction, but not in the forward torque direction.

[0081] According to another aspect, a vehicle is provided that includes a first electric motor, a second electric motor, and a transmission system, the transmission system including a first input shaft drivingly coupled to the first electric motor, a second input shaft drivingly coupled to the second electric motor, an output shaft, a first gear train including a first gear element fixed for rotation with the first input shaft, a second gear element rotatably mounted on the second input shaft, and a gear element rotatably mounted on the output shaft, a second gear train including a third gear element fixed for rotation with the first input shaft, a fourth gear element rotatably mounted on the second input shaft, and another gear element rotatably mounted on the output shaft, and a third gear element fixed for rotation with the first input shaft, a fourth gear element rotatably mounted on the second input shaft, and another gear element rotatably mounted on the output shaft, and a third gear element fixed for rotation with the first input shaft, a fourth gear element rotatably mounted on the second input shaft, and another gear element rotatably mounted on the output shaft. A drive train is provided that includes a gear selector assembly configured to selectively lock a gear element for rotation with an input shaft, and another gear selector assembly configured to selectively lock a gear element and another gear element for rotation with an output shaft, wherein at least one of the gear selector assemblies is configured to lock each of its gear elements for rotation with its respective input shaft selectively from among the following operating modes: a mode that locks the gear element for rotation with the shaft in forward torque and reverse torque directions, a mode that locks the gear element for rotation with the shaft in a forward torque direction, but not in a reverse torque direction; and a mode that locks the gear element for rotation with the shaft in a reverse torque direction, but not in a forward torque direction.

[0082] According to another aspect, a drive train is provided that includes a first electric motor, a second electric motor, and a transmission system, the transmission system including a first input shaft drivingly coupled to the first electric motor, a second input shaft drivingly coupled to the second electric motor, a first gear train including a first gear element mounted on the first input shaft and a second gear element mounted on the second input shaft, and a second gear train including a third gear element mounted on the first input shaft and a fourth gear element mounted on the second input shaft. The transmission may include an output member, a gear element mounted on the output member, and another gear element mounted on the output member. The transmission may include a gear selector assembly. The transmission may include another gear selector assembly. Each of the gear selector assembly and the another gear selector assembly may be a conventional gear selector assembly, such as a synchromesh gear selector assembly or a dog-type selector assembly.

[0083] According to another aspect, there is provided a vehicle including a drive train according to any of the configurations described herein. For example, the vehicle may include any one of a car, a hauler, a motorcycle, a bus, a van, an all-wheel drive vehicle, a tractor, a construction vehicle, and an excavation vehicle.

[0084] Embodiments will now be described, by way of example only, with reference to the accompanying drawings in which like reference symbols indicate equivalent features and in which: [Brief description of the drawings]

[0085] [Figure 1] 1 is a schematic diagram of a drive train according to a first embodiment, the drive train including a first electric motor and a second electric motor, and a transmission system. [Diagram 2] FIG. 2 is an isometric view of a gear selector assembly used in the drive train of FIG. [Figure 3a]FIG. 3 is an isometric view of a portion of the gear selector assembly of FIG. [Figure 3b] FIG. 3b is an exploded isometric view of a portion of the gear selector assembly of FIG. [Figure 4] FIG. 2 is a diagram showing an operating state of the drive train of FIG. 1. [Diagram 5] FIG. 2 is a diagram showing an operating state of the drive train of FIG. 1. [Figure 6] FIG. 2 is a diagram showing an operating state of the drive train of FIG. 1. [Figure 7] FIG. 2 is a diagram showing an operating state of the drive train of FIG. 1. [Figure 8] FIG. 2 is a diagram showing an operating state of the drive train of FIG. 1. [Figure 9] FIG. 2 is a diagram showing an operating state of the drive train of FIG. 1. [Figure 10] FIG. 2 is a diagram showing an operating state of the drive train of FIG. 1. [Figure 11] FIG. 2 is a diagram showing an operating state of the drive train of FIG. 1. [Figure 12] FIG. 2 is a diagram showing an operating state of the drive train of FIG. 1. [Figure 13] FIG. 2 is a diagram showing an operating state of the drive train of FIG. 1. [Figure 14] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a single motor state to a single motor state. [Figure 15] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a single motor state to a single motor state. [Figure 16] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a single motor state to a single motor state. [Figure 17] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a single motor state to a single motor state. [Figure 18] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a single motor state to a single motor state. [Figure 19] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a single motor state to a single motor state. [Figure 20] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a single motor state to a single motor state. [Figure 21] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a dual motor state to a dual motor state. [Figure 22] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a dual motor state to a dual motor state. [Figure 23] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a dual motor state to a dual motor state. [Figure 24] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a dual motor state to a dual motor state. [Diagram 25] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a dual motor state to a dual motor state. [Figure 26] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a dual motor state to a dual motor state. [Figure 27] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a dual motor state to a dual motor state. [Figure 28] FIG. 2 illustrates a power-on-up shift in the drive train of FIG. 1 from a dual motor state to a dual motor state. [Figure 29] 5 is a schematic diagram of a drive train according to a second embodiment, the drive train including a first electric motor and a second electric motor, and a transmission system. [Diagram 30]13 is a schematic diagram of a drive train according to a third embodiment, the drive train including a first electric motor and a second electric motor, and a transmission system. [Diagram 31] 13 is a schematic diagram of a drive train according to a fourth embodiment, the drive train including a first electric motor and a second electric motor, and a transmission system. [Diagram 32] 13 is a schematic diagram of a drive train according to a fifth embodiment, the drive train including a first electric motor and a second electric motor, and a transmission system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0086] In Fig. 1 a drive train 1 according to a first embodiment is shown diagrammatically. The drive train 1 comprises a first electric motor M1, a second electric motor M2 and a transmission 2. The drive train may be used in vehicles such as cars, transporters, motorcycles, buses, vans, all-wheel drive vehicles, tractors, construction vehicles and excavation vehicles. Alternatively, the drive train may be used in other applications such as manufacturing processes.

[0087] The transmission 2 includes a first input shaft 3. The first input shaft 3 is drivingly coupled to a first electric motor M1. For example, an output shaft of the first electric motor EM1 may be directly coupled to the first input shaft 3, for example, splined to the first input shaft 3. The transmission 2 includes a second input shaft 5. The second input shaft 5 is drivingly coupled to a second electric motor M2. For example, an output shaft of the second electric motor EM2 may be directly coupled to the second input shaft 5, for example, splined to the second input shaft 5.

[0088] The first input shaft 3 and the second input shaft 5 are arranged parallel to each other. The longitudinal axes of the first input shaft 3 and the second input shaft 5 are arranged spaced apart from each other, and therefore the first input shaft 3 and the second input shaft 5 are not coaxial.

[0089] The transmission includes an output member in the form of an output shaft 7. In a vehicle application, the output shaft 7 is typically connected to a differential which transmits drive power via an axle to the wheels of the vehicle.

[0090] The transmission 2 includes a first gear train 9 having a gear element 11 rotatably mounted on the first input shaft 3. The first gear train 9 includes a gear element 13 rotatably mounted on the second input shaft 5.

[0091] The transmission 2 includes a second gear train 15 having a gear element 17 rotatably mounted on the first input shaft 3. The second gear train 15 includes a gear element 19 rotatably mounted on the second input shaft 5.

[0092] The transmission 2 includes a third gear train 21 having a gear element 23 rotatably mounted on the first input shaft 3. The third gear train 21 includes a gear element 25 mounted on the output shaft 7. Preferably, the gear element 25 is fixed for rotation with the output shaft 7.

[0093] The transmission 2 includes a fourth gear train 27 having a gear element 29 rotatably mounted on the first input shaft 3. The fourth gear train 27 includes a gear element 31 mounted on the output shaft 7. Preferably, the gear element 31 is fixed for rotation with the output shaft 7.

[0094] The gear element 11 from the first gear train 9 and the gear element 23 from the third gear train 21 are rotatably mounted to the first input shaft 3 by means of a first sleeve 33. The gear element 11 and the gear element 23 are each fixed for rotation with the first sleeve 33. The first sleeve 33 is rotatably mounted to the first input shaft 3 by a bearing (not shown).

[0095] The gear element 17 from the second gear train 15 and the gear element 29 from the fourth gear train 27 are rotatably mounted to the first input shaft 3 by means of a second sleeve 35. The gear element 17 and the gear element 29 are each fixed for rotation with the second sleeve 35. The second sleeve 35 is rotatably mounted to the first input shaft 3 by bearings (not shown).

[0096] The gear element 13 from the first gear train 9 is rotatably mounted to the second input shaft 5 by means of a third sleeve 85. The gear element 13 is fixed for rotation with the third sleeve 85. The third sleeve 85 is rotatably mounted to the second input shaft 5 by a bearing (not shown).

[0097] A gear element 19 from the second gear train 15 is rotatably mounted to the second input shaft 5 by means of a fourth sleeve 87. The gear element 19 is fixed for rotation with the fourth sleeve 87. The fourth sleeve 87 is rotatably mounted to the second input shaft 5 by a bearing (not shown).

[0098] The transmission 2 includes a first gear selector assembly 37. The first gear selector assembly 37 is configured to selectively lock the first sleeve 33 for rotation with the first input shaft 3, and thus selectively lock gear element 11 and gear element 23 for rotation with the first input shaft 3. The first gear selector assembly 37 is configured to selectively lock the second sleeve 35 for rotation with the first input shaft 3, and thus selectively lock gear element 17 and gear element 29 for rotation with the first input shaft 3.

[0099] The transmission 2 includes a second gear selector assembly 39. The second gear selector assembly 39 is configured to selectively lock the third sleeve 85 for rotation with the second input shaft 5, and thus the gear element 13 of the first gear train 9 for rotation with the second input shaft 5. The second gear selector assembly 39 is configured to selectively lock the fourth sleeve 87 for rotation with the second input shaft 5, and thus the gear element 19 of the second gear train 15 for rotation with the second input shaft 5.

[0100] The first gear selector assembly 37 is configured to engage with a drive arrangement 41 located on the first sleeve 33 (see FIG. 1). The first selector assembly 37 is configured to engage with a drive arrangement 43 located on the second sleeve 35 (see FIG. 1). The drive arrangements 41, 43 each comprise a group of dogs. The dogs 41 of the first group are located towards one end of the first sleeve 33. The dogs 43 of the second group are located towards one end of the second sleeve 35. There are typically three dogs in each group 41, 43. The dogs in a group are evenly distributed circumferentially around the first input shaft 3, i.e. the angle between the centres of a pair of dogs is about 120 degrees. Three dogs are preferably used because this configuration provides a relatively large engagement window, or spacing between the dogs, for receiving the engagement members from the first selector assembly 37. Three dogs also provide inherent self-centering and even load distribution. The large engagement window provides a greater likelihood that the first selector assembly 37 will fully engage the first and second sleeves 33, 35.

[0101] The first selector assembly 37 is mounted on the first input shaft 3 between a drive arrangement 41 mounted on the first sleeve 33 and a drive arrangement 43 mounted on the second sleeve 35 .

[0102] The first gear selector assembly 37 includes a first set of engaging members 45 and a second set of engaging members 46, and an actuator mechanism 47 (see Figures 2, 3a and 3b). The first set of engaging members 45 includes three members 45a-c evenly distributed around the first input shaft 3. The second set of engaging members 46 includes three members 46a-c evenly distributed around the first input shaft 3.

[0103] The first set of engagement members 45 and the second set of engagement members 46 are mounted to a support 49 that is mounted to the first input shaft 3 (see Figures 3a and 3b). Each set of engagement members 45, 46 is configured to rotate with the first input shaft 3 but can slide axially along the support 49, and thus along the first input shaft 3, in response to switching action of the actuator mechanism 47. To facilitate this, the support 49 includes six keyways 51 formed in its curved surface, each configured to receive a respective engagement member 45a-c, 46a-c. Each keyway 51 is profiled to radially and tangentially constrain its respective engagement member 45a-c, 46a-c within the keyway 51, but not axially (see Figure 3b).

[0104] The support 49 includes internal splines 49a that are configured to engage external splines formed on the first input shaft 3. This provides a very robust connection between the support 49 and the first input shaft 3. The splined arrangement locks the support 49, and therefore the first and second sets of engaging members 45, 46, for rotation with the first input shaft 3.

[0105] The configuration of each set of engaging members 45, 46 is such that a particular set of members 45a-c, 46a-c is positioned in every other keyway 51 such that the sets of members 45, 46 can slide along the support 49. The first set of engaging members 45a-c are rigidly connected to each other by a first annular connector member 53 and move as a unit. Thus, the first set of engaging members 45a-c and the first annular connector member 53 together form a first gear selector ring. The first set of engaging members 45a-c are evenly distributed around the first annular connector member 53. The second set of engaging members 46a-c are rigidly connected to each other by a second annular connector member 55 and move as a unit. Thus, the second set of engaging members 46a-c and the second annular connector member 55 together form a second gear selector ring. The second set of engaging members 46a-c are evenly distributed around the second annular connector member 55. Each set of engaging members 45, 46 can move independently of the other. When there is relative movement between the first set of engaging members 45 and the second set of engaging members 46, the first annular connector member 53 moves over the second set of engaging members 46 and the second annular connector member 55 moves over the first set of engaging members 45.

[0106] Each annular connector member 53,55 has a groove 57 formed in its outer curved surface which extends completely around the respective annular connector member 53,55.

[0107] Each of the first set of engagement members 45a-45c has a first end 59 configured to engage a first group of dogs 41 mounted on the first sleeve 33 and a second end 61 configured to engage a second group of dogs 43 mounted on the second sleeve 35. The first end 59 and second end 61 typically have the same configuration but are oppositely oriented, e.g., the first end 59 of each first engagement member 45a-c is configured to selectively engage the first group of dogs 41 during deceleration of the first sleeve 33 (reverse torque direction) and the second end 61 is configured to selectively engage the second group of dogs 43 during acceleration of the second sleeve 35 (forward torque direction). For each engagement member 46a-c of the second set, the first end 63 is configured to engage with the second group of dogs 43 during deceleration (reverse torque direction) of the second sleeve 35, and the second end 65 is configured to engage with the first group of dogs 41 during acceleration (forward torque direction) of the first sleeve 33.

[0108] When both the first set of engagement members 45 and the second set of engagement members 46 engage with one of the first set of dogs 41 and the second set of dogs 43, driving forces are transmitted between each sleeve 33, 35 and the first gear selector assembly 37 in forward and reverse torque directions.

[0109] Each of the first and second ends 59, 61, 63, 65 of the engagement members includes a drive surface 67 for drivingly engaging the respective dog 41, 43, a non-drive surface in the form of a ramp 69, an end surface 71, and may include a shoulder 73 (see FIG. 3b). The end surface 71 limits the axial movement of the engagement members 45a-c, 46a-c. In some configurations, the sides of the dogs 41, 43 may be angled. In this example, the drive surface 67 may be angled to complement the sides of the dogs 41, 43, so that as the engagement members 45a-c, 46a-c rotate into engagement, there is face-to-face contact to reduce wear. The purpose of the non-drive surface 69 is to prevent locking engagement between the engagement members and the dogs 41, 43. Each non-drive surface 69 is preferably helically shaped and angled away from its respective end surface 71. The angle of inclination of the non-drive surface 45 may be such that the longitudinal distance between the edge of the non-drive surface furthest from the end surface 71 and the plane of the end surface 71 is greater than the height of the dogs 41, 43. This helps ensure that the transmission does not lock up when there is relative rotational movement between the engagement members 45a-c, 46a-c and the dogs 41, 43 which moves the non-drive surface 69 towards the respective dog 41, 43. The dogs 41, 43 do not impinge on the sides of the engagement members 45a-c, 46a-c, but rather engage the non-drive surface 69. Further relative rotational movement between the dogs 41, 43 and the engagement members 45a-c, 46a-c causes the dogs 41, 43 to slide across the non-drive surface 69, the helical surface of which causes the engagement members 45a-c, 46a-c to move axially along the first input shaft 3 away from their respective dogs 41, 43, and therefore the transmission does not lock up. The non-drive surface 69 thus provides a ratcheting effect such that the first gear selector assembly 37 is configured to slide relative to the first and second sleeves 33, 35, respectively, under some operating conditions.

[0110] Because the first and second sets of engaging members 45 and 46 can move independently of one another, the first gear selector assembly 37 can first select the first sleeve 33 using one of the first and second sets of engaging members 45 and 46. The other of the first and second sets of engaging members 45 and 46 then engages the first sleeve 33. Similarly, the first gear selector assembly 37 can first select the second sleeve 35 using one of the first and second sets of engaging members. The other of the first and second sets of engaging members 45 and 46 then engages the second sleeve 35.

[0111] Thus, the first gear selector assembly 37 is configured to selectively engage the first sleeve 33 from among the following modes of operation: fully engaged in both forward and reverse torque directions; disengaged in both torque directions (neutral); engaged in forward torque direction but disengaged in reverse torque direction; and disengaged in forward torque direction but engaged in reverse torque direction. The first gear selector assembly 37 is configured to selectively engage the second sleeve 35 from among the following modes of operation: fully engaged in both forward and reverse torque directions; disengaged in both torque directions (neutral); engaged in forward torque direction but disengaged in reverse torque direction; and disengaged in forward torque direction but engaged in reverse torque direction.

[0112] When the first and second set of members 45, 46 are interleaved (see FIG. 3a), the drive surface 67 of the first end 59 of the first set of members 45 is adjacent to the drive surface 67 of the first end 63 of the second set of members 46. When the first and second set of members 45, 46 are fully engaged with the first sleeve 33, a dog 41 is positioned between each pair of adjacent drive surfaces 67. When the first and second set of members 45, 46 are fully engaged with the second sleeve 35, a dog 43 is positioned between each pair of adjacent drive surfaces 67 of the second ends 61, 63 of the engagement members. The dimensions of the dogs 41, 43 and the ends 59, 61, 63, 65 of the engagement members are such that there is little movement of each dog between the drive surface 67 of the acceleration member and the drive surface 67 of the reduction member when the sleeves 33, 35 move from acceleration to deceleration or vice versa to ensure that there is little or no backlash in the gears. Backlash is the lost motion experienced when the dog moves from the drive surface 67 of the acceleration member to the drive surface 67 of the reduction member when moving from acceleration to deceleration or vice versa. A conventional dog type transmission has a backlash of about 30 degrees. A typical transmission for a car according to this embodiment has a backlash of less than 5 degrees.

[0113] When the first and second sets of members 45, 46 are fully engaged with their respective sleeves 33, 35 and the dogs 41, 43 are positioned between respective pairs of adjacent drive surfaces 67, one of the first and second sets of engagement members 45, 46 will be in a loaded state and the other of the first and second sets of engagement members 45, 46 will be in an unloaded state. The unloaded set of engagement members can move out of engagement with the currently engaged gear element during gear shifting.

[0114] The actuator mechanism 47 includes a shift cradle 75. The mechanism 47 is configured to actuate the first set of engagement members 45 and the second set of engagement members 46 using only a single actuator, such as a shift drum 77 and shift forks 79a, 79b. Preferably, the shift cradle 75 includes a resilient means, such as a wound spring 80. The spring 80 is configured to bias the first set of engagement members 45 and the second set of engagement members 46 to move axially when the first set of engagement members 45 and the second set of engagement members 46 are in driving engagement with the sleeves 33, 35 and cannot move.

[0115] The second gear selector assembly 39 has a similar configuration to the first gear selector assembly 37 .

[0116] The third sleeve 85 includes a third set of drive arrangements 81 positioned towards one end of the sleeve. The fourth sleeve 87 includes a fourth set of drive arrangements 83. The second gear selector assembly 39 is mounted on the second input shaft 5 between the third set of drive arrangements 81 and the fourth set of drive arrangements 83. The second gear selector assembly 39 is configured to selectively engage the third set of drive arrangements 81 with the first set of engagement members 45 and the second set of engagement members 46 to selectively lock the third sleeve 85, and thus the gear element 13, for rotation with the second input shaft 5. The second gear selector assembly 39 is configured to selectively engage the fourth set of drive arrangements 83 with the first set of engagement members 45 and the second set of engagement members 46 to selectively lock the fourth sleeve 87, and thus the gear element 19, for rotation with the second input shaft 5.

[0117] The second gear selector assembly 39 is configured to selectively engage the third sleeve 85, and thus the gear element 13, from among the following operating modes: fully engaged in both forward and reverse torque directions; disengaged in both torque directions (neutral); engaged in forward torque direction but disengaged in reverse torque direction; and disengaged in forward torque direction but engaged in reverse torque direction. The second gear selector assembly 39 is configured to selectively engage the fourth sleeve 87, and thus the gear element 19, from among the following operating modes: fully engaged in both forward and reverse torque directions; disengaged in both torque directions (neutral); engaged in forward torque direction but disengaged in reverse torque direction; and disengaged in forward torque direction but engaged in reverse torque direction.

[0118] The drive train 1 may include a control system. Movement of the first and second sets of engagement members 45, 46 for each of the gear selector assemblies 37, 39 may be controlled by the control system to provide fully automatic or semi-automatic gear shifting. The control system may also control operation of the first and second electric motors M1, M2.

[0119] The operating states of the drive train 1 are shown in figures 4 to 13. In figures 4 to 13:

[0120] Reference character "A" represents a condition in which the first gear selector assembly 37 has locked the second sleeve 35 for rotation with the first input shaft 3 in both forward and reverse torque directions;

[0121] Reference character "B" represents a condition in which the first gear selector assembly 37 has locked the first sleeve 33 for rotation with the first input shaft 3 in both forward and reverse torque directions;

[0122] Reference character "C" represents a condition in which the second gear selector assembly 39 has locked the fourth sleeve 87 for rotation with the second input shaft 5 in both the forward and reverse torque directions;

[0123] Reference character "D" represents a condition in which the second gear selector assembly 39 locks the third sleeve 85 for rotation with the second input shaft 5 in both the forward and reverse torque directions.

[0124] Operating state 1 is the neutral state in which no torque is provided to the output shaft 7 .

[0125] Each of the operating states 2-9 provides a torque to the output shaft 7. Typically, each of the operating states 2-9 has a different effective gear ratio (gear output) than the other operating states. Thus, the transmission 2 can provide eight different effective gear ratios (gear outputs). Thus, in the described layout, a relatively large number of outputs can be provided with a relatively small number of gear trains.

[0126] In some operating conditions, the output shaft 7 is driven only by the first electric motor M1. In some operating conditions, the output shaft 7 is driven only by the second electric motor M2. In some operating conditions, the output shaft 7 is driven simultaneously by the first electric motor M1 and the second electric motor M2. In operating conditions where torque is provided to the output shaft 7 by both motors, the torques are additive. Of course, in any given use of the drive train, all or a subsection of the available operating conditions of the transmission may be made available to the user to meet the application requirements.

[0127] In operational state 2, torque is provided from the first electric motor M1 to the output shaft 7 via the fourth gear train 27. The first gear selector assembly 37 locks the second sleeve 35 for rotation with the first input shaft 3 in the forward and reverse torque directions. The second electric motor M2 is not operating. The second gear selector assembly 39 is in neutral.

[0128] In operational state 3, torque is provided from the first electric motor M1 to the output shaft 7 via the third gear train 21. The first gear selector assembly 37 locks the first sleeve 33 for rotation with the first input shaft 3 in the forward and reverse torque directions. The second electric motor M2 is not operating. The second gear selector assembly 39 is in neutral.

[0129] In operating state 4, torque is provided from the second electric motor M2 to the output shaft 7 via the second gear train 15 and the fourth gear train 27. The second gear selector assembly 39 locks the fourth sleeve 87 for rotation with the second input shaft 5 in the forward and reverse torque directions. The first electric motor M1 is not operating. The first gear selector assembly 37 is in neutral.

[0130] In the operating state 5, torque is provided from the second electric motor M2 to the output shaft 7 via the first gear train 9 and the third gear train 21. The second gear selector assembly 39 locks the third sleeve 85 for rotation with the second input shaft 5 in the forward and reverse torque directions. The first electric motor M1 is not operating. The first gear selector assembly 37 is in a neutral state.

[0131] In operating state 6, torque is provided from the first electric motor M1 to the output shaft 7 via the fourth gear train 27 and from the second electric motor M2 to the output shaft 7 via the first gear train 9 and the third gear train 21. The first gear selector assembly 37 locks the second sleeve 35 for rotation with the first input shaft 3 in the forward and reverse torque directions. The second gear selector assembly 39 locks the third sleeve 85 for rotation with the second input shaft 5 in the forward and reverse torque directions.

[0132] In operating state 7, torque is provided from the first electric motor M1 to the output shaft 7 via the third gear train 21 and from the second electric motor M2 to the output shaft 7 via the first gear train 9 and the third gear train 21. The first gear selector assembly 37 locks the first sleeve 33 for rotation with the first input shaft 3 in the forward and reverse torque directions. The second gear selector assembly 39 locks the third sleeve 85 for rotation with the second input shaft 5 in the forward and reverse torque directions.

[0133] In operating state 8, torque is provided from the first electric motor M1 to the output shaft 7 via the third gear train 21 and from the second electric motor M2 to the output shaft 7 via the second gear train 15 and the fourth gear train 27. The first gear selector assembly 37 locks the first sleeve 33 for rotation with the first input shaft 3 in the forward and reverse torque directions. The second gear selector assembly 39 locks the fourth sleeve 87 for rotation with the second input shaft 5 in the forward and reverse torque directions.

[0134] In operating state 9, torque is provided from the first electric motor M1 to the output shaft 7 via the fourth gear train 27 and from the second electric motor M2 to the output shaft 7 via the second gear train 15 and the fourth gear train 27. The first gear selector assembly 37 locks the second sleeve 35 for rotation with the first input shaft 3 in the forward and reverse torque directions. The second gear selector assembly 39 locks the fourth sleeve 87 for rotation with the second input shaft 5 in the forward and reverse torque directions.

[0135] Thus, during at least some operating conditions, torque may be provided from the first electric motor M1 and the second electric motor M2 to the output shaft via at least one common gear train, which helps provide a compact transmission system. During at least some operating conditions, torque may be provided from the first electric motor M1 and the second electric motor M2 to the output shaft via different gear trains.

[0136] In operating conditions where torque is provided to the output shaft 7 by both the first electric motor M1 and the second electric motor M2, the control system controls operation of the motors to ensure that they operate at speeds appropriate for the gear trains, selected to match the speed at the output shaft.

[0137] In one possible configuration for a vehicle: operating state 9 can correspond to first gear; operating state 8 can correspond to second gear; operating state 4 can correspond to third gear; operating state 6 can correspond to fourth gear; operating state 2 can correspond to fifth gear; operating state 7 can correspond to sixth gear; operating state 5 can correspond to seventh gear; operating state 3 can correspond to eighth gear. It will be apparent from this configuration and the above operating states that each of the first electric motor M1 and the second electric motor M2 can provide torque to the output shaft through both odd and even gears.

[0138] An important advantage of the drive train 1 is that it provides torque support to the output shaft 7 during gear shifting. When torque support is provided, there is no significant loss of drive power to drive the vehicle wheels during gear shifting. The drive train may be configured to provide torque support in the following shift types: power on up shift, power on down shift, power off up shift, and power off down shift.

[0139] 14-20 show a power-on upshift from a first single motor operating state (operating state 4) to a second single motor operating state (operating state 2). FIG. 15 shows the drive train 1 in operating state 4, with the output shaft 7 driven only by the second electric motor M2. The first gear selector assembly 37 is in neutral. The second gear selector assembly 39 is fully engaged with the fourth sleeve 87. Torque is provided from the second electric motor M2 to the output shaft via the second gear train 15 and the fourth gear train 27. During a gear shift to operating state 2, the first electric motor M1 is activated and synchronized to the rotational speed of the second sleeve 35. This has the effect of synchronizing the rotational speed of the first input shaft 3 and the engagement members 45, 46 of the first gear selector assembly 37 with the rotational speed of the second sleeve 35 (see FIG. 16). The first gear selector assembly 37 engages the second sleeve 35. The first gear selector assembly 37 first engages the second sleeve 35 with one of the first and second sets of engagement members 45 and 46, and then follows up with the other of the first and second sets of engagement members, thereby locking the second sleeve 35 for rotation with the first input shaft 3 in the forward and reverse torque directions (see FIG. 17). Torque is provided from the first electric motor M1 to the output shaft via the fourth gear train 27. At this stage, torque is temporarily provided to the output shaft 7 by both the first and second electric motors M1 and M2 (see FIG. 18). When the first gear selector assembly 37 engages the second sleeve 35, the loaded set of engagement members 45, 46 of the second gear selector assembly 39 is unloaded and the second gear selector assembly 39 then disengages the fourth sleeve 87, effectively decoupling the second electric motor M2 from the output shaft 7 (see FIG. 19). It can be seen from the torque graph of FIG. 19 that torque is continuously provided to the output shaft 7 during the torque handover from the second electric motor M2 to the first electric motor M1.FIG. 20 shows that the gear shift has been completed and is running in operating state 2, with the second electric motor M2 moving to a non-operating state.

[0140] 21-28 illustrate a power-on upshift from a first dual motor operating state (operating state 9) to a second dual motor operating state (operating state 8). FIG. 22 illustrates the drive train 1 in operating state 9, with the output shaft 7 driven by both the first electric motor M1 and the second electric motor M2. The first gear selector assembly 37 is fully engaged with the second sleeve 35. Torque is provided from the first electric motor M1 to the output shaft 7 via the fourth gear train 27. The second gear selector assembly 39 is fully engaged with the fourth sleeve 87. Torque is provided from the second electric motor M2 to the output shaft 7 via the second gear train 15 and the fourth gear train 27. During a gear shift to operating state 8, the torque output from the second electric motor M2 increases while simultaneously the torque output from the first electric motor M1 decreases (see FIG. 23). This unloads the loaded set of engagement members 45, 46 and the first gear selector assembly 37 disengages from the second sleeve 35 and moves to a neutral position (see FIG. 24), so that temporarily no torque is provided by the first electric motor M1 to the output shaft 7. The speed of the first electric motor M1 is then synchronized with the rotational speed of the first sleeve 33 (see FIG. 25). The first gear selector assembly 37 then engages the first sleeve 33. The first gear selector assembly 37 first engages the first sleeve 33 with one of the first and second sets of engagement members 45, 46 and then follows up with the other of the first and second sets of engagement members 45, 46 to fully engage the first sleeve 33 (see FIG. 26). Torque is then supplied from the first electric motor M1 to the output shaft via the third gear train 21 (see FIG. 27). It can be seen from the torque graph in FIG. 27 that, during the gear train change from the fourth gear train 27 to the third gear train 21, torque from the first electric motor M1 is temporarily decoupled from the output shaft 7, yet torque is continuously provided to the output shaft 7 by the second electric motor M2.FIG. 28 shows that the gear shift is completed and in operating state 8, torque is being supplied to the output shaft 7 by both the first electric motor M1 and the second electric motor M2 simultaneously.

[0141] Other shift types can be performed in a similar fashion.

[0142] It will be appreciated that torque spikes are substantially eliminated by a speed synchronization step in the shift strategy prior to engaging the new gear. Synchronization is possible because the transmission layout provides two drive input paths, one direct from the first electric motor M1 and the other direct from the second electric motor M2.

[0143] Drive trains can be used in vehicular and non-vehicular applications. Typical vehicles include cars, trucks, motorcycles, buses, vans, all-wheel drive vehicles, tractors, construction vehicles, and excavation vehicles. Non-vehicular applications include manufacturing machinery, wind turbines, etc.

[0144] A drive train 101 according to a second embodiment is shown in FIG. 29. The second embodiment is similar to the first embodiment, except that instead of having a third gear train 21 and a fourth gear train 27, the gear elements 25, 35 mounted on the output shaft 7 are part of the first gear train 9 and the second gear train 15, respectively. That is, the first gear train 9 includes a gear element 11 rotatably mounted on the first input shaft 3, a gear element 13 rotatably mounted on the second input shaft 5, and a gear element 25 fixed for rotation with the output shaft 7. The second gear train 15 includes a gear element 17 rotatably mounted on the first input shaft 3, a gear element 19 rotatably mounted on the second input shaft 5, and a gear element 31 fixed for rotation with the output shaft 7.

[0145] The second embodiment has the same operating conditions as the first embodiment outlined in the table of FIG. 4, however, some of the torque paths are different from the first embodiment due to the absence of the third and fourth gear trains.

[0146] The second embodiment is a simplified and more compact version of the first embodiment, but has less flexibility in selecting the relative sizes of the gear elements and less flexibility in selecting the relative power of the first electric motor M1 and the second electric motor M2 than the first embodiment, i.e. the first embodiment provides more flexibility to fine-tune the selection of the relative sizes of the gear elements and the relative power of the first electric motor M1 and the second electric motor M2, so that for example one of the two motors M1, M2 is better suited for rapid acceleration purposes or for energy efficient driving purposes.

[0147] A drive train 201 according to a third embodiment is shown in FIG. 30. The third embodiment is a hybrid version of the first and second embodiments. Instead of having a third gear train 21, the gear element 25 mounted on the output shaft 7 is part of the first gear train 9. That is, the first gear train 9 includes a gear element 11 rotatably mounted on the first input shaft 3, a gear element 13 rotatably mounted on the second input shaft 5, and a gear element 25 fixed to rotate with the output shaft 7. However, unlike the second embodiment, the third embodiment has a similar configuration to the first embodiment for the second gear train 15 and the fourth gear train 27.

[0148] The third embodiment has the same operating conditions as the first embodiment outlined in the table of FIG. 4, however, some of the torque paths are different from the first embodiment due to the absence of a third gear train.

[0149] The third embodiment variant, not shown, is similar to the third embodiment except that it includes the first gear train 9 and third gear train 21 of the first embodiment and the second gear train 15 of the second embodiment. The third embodiment variant has the same operating conditions as the first embodiment outlined in the table of Figure 4, but some of the torque paths are different from the first embodiment due to the absence of the fourth gear train.

[0150] The third embodiment provides more flexibility in selecting the relative sizes of the gear elements and the relative power of the first motor M1 and the second motor M2 than the second embodiment, but not as much flexibility as the first embodiment, but the third embodiment is smaller than the first embodiment.

[0151] A drive train 301 according to a fourth embodiment is shown in FIG. 31. The fourth embodiment is similar to the second embodiment, except that the second gear selector assembly 39 is mounted on the output shaft 7 instead of the second input shaft 5. Gear element 13 and gear element 19 are fixed for rotation with the second input shaft 5. Gear element 25 and gear element 31 are rotatably mounted on the output shaft 7. The second gear selector assembly 39 is configured to selectively lock gear element 25 and gear element 31 for rotation with the output shaft 7.

[0152] A drive train 401 according to a fifth embodiment is shown in FIG. 32. The fifth embodiment is similar to the second embodiment, except that the first gear selector assembly 37 is mounted on the output shaft 7 instead of the first input shaft 3. Gear elements 11 and 17 are fixed for rotation with the first input shaft 3. Gear elements 25 and 31 are rotatably mounted on the output shaft 7. The first gear selector assembly 37 is configured to selectively lock gear elements 25 and 31 for rotation with the output shaft 7.

[0153] The fourth and fifth embodiments each have 11 states, 10 operating states and neutral, which is more than the first to third embodiments. However, a drawback of the fourth and fifth embodiments is that it is not always possible to synchronize the speed of one of the motors to the new gear as effectively as in the first to third embodiments, so there is a risk of torque spikes occurring when shifting between at least some of the operating states. In at least some shifts, at least one of the gear selector assemblies 37, 39 engages a new gear element while the current gear element is still engaged, and there is a speed difference between the newly engaged gear element and the motors M1, M2 driving the selector assemblies 37, 39, so torque spikes may occur.

[0154] Those skilled in the art will appreciate that the above described embodiments may be modified within the scope of the claims, for example, in some embodiments, only one of the gear selector assemblies may be of the type described above. The other gear selector assembly may be a conventional dog or synchromesh selector assembly. However, it is preferred to have each of the gear selector assemblies as the type described above, as this provides gear selection advantages such as early engagement of the gear elements without concern of locking up the transmission, compact construction, and no need for expensive synchronizing cones.

[0155] In some embodiments, both the first selector assembly and the second selector assembly may be of a conventional type, such as a synchromesh or dog type gear selector assembly, but such an arrangement eliminates the advantages of having a selector assembly of the type described above and typically results in a less compact transmission, especially if synchronizers are used.

[0156] In some embodiments, the first motor M1 and the second motor M2 are similar. In other embodiments, the first motor M1 and the second motor M2 are different. For example, one of the first motor M1 and the second motor M2 may have characteristics that are more suitable for rapid acceleration, low speeds, and starting the vehicle. One of the first motor M1 and the second motor M2 may have characteristics that are more suitable for cruising speeds, for example, for highway driving.

[0157] The actuator mechanism 47 may be configured differently from that described above. For example, the actuator mechanism may include a first actuator and a second actuator, and a first actuator member and a second actuator member. The first actuator and the second actuator may be force generator actuators, preferably part of an electrical system, e.g. an electromechanical or electrohydraulic system. The first actuator member and the second actuator member are mechanical drive members, preferably in the form of independently controllable shift forks, that transmit forces from the first actuator and the second actuator to the respective sets of engagement members. The first set of engagement members 45 is driven by the first actuator via the first shift fork, and the second set of engagement members 46 is driven by the second actuator via the second shift fork. Thus, the first set of engagement members 45 and the second set of engagement members 46 move completely independently of each other.

[0158] In some configurations, in at least one gear element of the transmission, instead of having the drive arrangement mounted on an associated component (sleeve), the drive arrangement may be formed on or attached directly to the gear element.

Claims

1. The electric motor includes a first electric motor, a second electric motor, and a transmission system, the transmission system including a first input shaft drivingly connected to the first electric motor, a second input shaft drivingly connected to the second electric motor, an output member, a first gear train including a first gear element rotatably mounted on the first input shaft and a second gear element rotatably mounted on the second input shaft, the first gear element meshing with the second gear element, a second gear train including a third gear element rotatably mounted on the first input shaft and a fourth gear element rotatably mounted on the second input shaft, the third gear element meshing with the fourth gear element, and a transmission system including a first input shaft and a second input shaft. and another gear selector assembly configured to selectively lock the second gear element and the fourth gear element for rotation with the second input shaft, at least one of the gear selector assemblies configured to lock each of its gear elements for rotation with its respective input shaft selectively from among the following operating modes: a mode that locks the gear element for rotation with the input shaft in forward and reverse torque directions, a mode that locks the gear element for rotation with the input shaft in the forward torque direction, but not in the reverse torque direction; and a mode that locks the gear element for rotation with the input shaft in the reverse torque direction, but not in the forward torque direction.

2. A drive train as described in claim 1, wherein the output member includes the output shaft.

3. 3. A drive train as claimed in claim 1 or 2, wherein the transmission system includes a gear element mounted to the output member.

4. 4. The drive train of claim 3, wherein said gear element mounted to said output member is fixed for rotation therewith.

5. 5. A drive train as claimed in claim 3 or 4, wherein the gear element mounted on the output member is part of the first gear train.

6. the transmission system includes a third gear train, the third gear train including a fifth gear element rotatably mounted on the first input shaft and the gear element mounted on the output member; the first gear element and the fifth gear element are fixedly attached to a first sleeve, the first sleeve is rotatably mounted to the first input shaft, and the gear selector assembly is configured to selectively lock the first sleeve for rotation with the first input shaft; 5. The drive train of claim 3 or 4, wherein the gear selector assembly is configured to lock the first sleeve for rotation with the first input shaft selectively from among operating modes including a mode in which the first sleeve is locked for rotation with the first input shaft in a forward torque direction and a reverse torque direction, a mode in which the first sleeve is locked for rotation with the first input shaft in the forward torque direction but not in the reverse torque direction, and a mode in which the first sleeve is locked for rotation with the first input shaft in the reverse torque direction but not in the forward torque direction.

7. 7. A drive train as claimed in any one of claims 3 to 6, wherein the transmission system includes a further gear element mounted to the output member.

8. 8. The drive train of claim 7, wherein the further gear element mounted to the output member is fixed for rotation with the output member.

9. 9. A drive train as claimed in claim 7 or 8, wherein the gear element mounted on the output member is part of the second gear train.

10. the transmission system including a fourth gear train, the fourth gear train including a sixth gear element rotatably mounted on the first input shaft and the further gear element mounted on the output member; the third gear element and the sixth gear element are fixedly attached to a second sleeve, the second sleeve is rotatably mounted to the first input shaft, and the gear selector assembly is configured to selectively lock the second sleeve for rotation with the first input shaft; 9. The drive train of claim 7 or 8, wherein the gear selector assembly is configured to lock the second sleeve for rotation with the first input shaft selectively from among operating modes including a mode in which the second sleeve is locked for rotation with the first input shaft in forward and reverse torque directions, a mode in which the second sleeve is locked for rotation with the first input shaft in the forward torque direction but not in the reverse torque direction, and a mode in which the second sleeve is locked for rotation with the first input shaft in the reverse torque direction but not in the forward torque direction.

11. During a gear shift, the speed of one of the first electric motor and the second electric motor is synchronized with the speed of a new gear; 11. A drive train as claimed in any one of claims 1 to 10, wherein synchronisation of the speed of the electric motor to the new gear occurs before each gear selector assembly engages the new gear.

12. a first electric motor, a second electric motor, and a transmission system, the transmission system including a first input shaft drivingly coupled to the first electric motor, a second input shaft drivingly coupled to the second electric motor, an output member, a first gear train including a first gear element rotatably mounted on the first input shaft, a second gear element fixed for rotation with the second input shaft, and a gear element rotatably mounted on the output member, a second gear train including a third gear element rotatably mounted on the first input shaft, a fourth gear element fixed for rotation with the second input shaft, and another gear element rotatably mounted on the output member, and a transmission system connecting the first gear element and the third gear element to the first input shaft. and another gear selector assembly configured to selectively lock the gear element and the further gear element for rotation with the output member, at least one of the gear selector assemblies configured to lock each of its gear elements for rotation with its respective shaft selectively from among the following operating modes: a mode in which the gear element is locked for rotation with the shaft in forward and reverse torque directions, a mode in which the gear element is locked for rotation with the shaft in the forward torque direction, but not in the reverse torque direction; and a mode in which the gear element is locked for rotation with the shaft in the reverse torque direction, but not in the forward torque direction.

13. The present invention relates to an electric motor for a vehicle, the electric motor comprising: a first electric motor, a second electric motor, and a transmission system, the transmission system including a first input shaft drivingly coupled to the first electric motor, a second input shaft drivingly coupled to the second electric motor, an output member, a first gear train including a first gear element fixed for rotation with the first input shaft, a second gear element rotatably mounted on the second input shaft, and a gear element rotatably mounted on the output member, a second gear train including a third gear element fixed for rotation with the first input shaft, a fourth gear element rotatably mounted on the second input shaft, and another gear element rotatably mounted on the output member, and a transmission system including a first input shaft and a second input shaft, the second gear element and the fourth gear element being coupled to the second input shaft. and another gear selector assembly configured to selectively lock the gear element and the further gear element for rotation with the output member, wherein at least one of the gear selector assemblies is configured to lock each of its gear elements for rotation with its respective input shaft selectively from among the following operating modes: a mode that locks the gear element for rotation with the shaft in forward and reverse torque directions, a mode that locks the gear element for rotation with the shaft in the forward torque direction, but not in the reverse torque direction; and a mode that locks the gear element for rotation with the shaft in the reverse torque direction, but not in the forward torque direction.

14. The drive train of claim 6 , wherein in at least one operating condition torque is provided from said first electric motor through said third gear train to said output member.

15. The drive train of claim 10 , wherein in at least one operating condition, torque is provided from the first electric motor through the fourth gear train to the output member.

16. 16. A drive train as claimed in any one of the preceding claims, wherein in at least one operating condition torque is provided from the second electric motor through the first gear train to the output member.

17. 17. A drive train as claimed in any one of the preceding claims, wherein in at least one operating condition torque is provided from the second electric motor through the second gear train to the output member.

18. The drive train of claim 6 , wherein in at least one operating condition torque is provided from said second electric motor through said third gear train to said output member.

19. The drive train of claim 10 , wherein in at least one operating condition torque is selectively provided from said second electric motor through said fourth gear train to said output member.

20. 20. A drive train as claimed in any one of claims 1 to 19, wherein in at least one operating condition torque is provided to the output member by the first electric motor and not by the second electric motor.

21. 21. A drive train as claimed in any one of claims 1 to 20, wherein in at least one operating condition torque is provided to the output member by the second electric motor and not by the first electric motor.

22. 22. A drive train as claimed in any one of the preceding claims, wherein in at least one operating condition torque is provided to the output member by the first electric motor and the second electric motor simultaneously.

23. 23. The drive train of claim 22, wherein in at least one operating condition torque is provided to the output member by the first electric motor and the second electric motor simultaneously through different gear trains.

24. 24. A drive train as claimed in claim 22 or 23, wherein in at least one operating condition torque is provided to the output member by the first electric motor and the second electric motor simultaneously via a common gear train.

25. 25. A drive train as claimed in any preceding claim, configured to provide torque support to the output member during gear shifting.

26. 26. The drive train of claim 1 , configured such that during a gear shift, the torque output of one of the first electric motor and the second electric motor is decreased and the torque output of the other of the first motor and the second motor is increased.

27. 27. A drive train as claimed in any one of the preceding claims, wherein at least one of the gear selector assemblies includes a first set of engaging members and a second set of engaging members that are movable independently of one another.

28. A drive train as described in claim 27 when dependent on claim 12 or 13, wherein the first set of engaging members and the second set of engaging members are configured such that the first set of engaging members and the second set of engaging members select the gear elements mounted on the output member, such that in a state where a braking force is transmitted, the first set of engaging members are drivingly engaged with drive arrangements associated with the gear elements and the second set of engaging members are in an unloaded state, and in a state where a driving force is transmitted, the second set of engaging members are drivingly engaged with drive arrangements associated with the gear elements and the first set of engaging members are in an unloaded state.

29. A drive train as described in claim 27 dependent on claim 12 or 13, wherein the first set of engaging members and the second set of engaging members may be configured such that the first set of engaging members and the second set of engaging members select the other gear element mounted on the output member, such that in a state where a driving force is transmitted, the first set of engaging members are drivingly engaged with a drive arrangement associated with the other gear element and the second set of engaging members are in an unloaded state, and in a state where a braking force is transmitted, the second set of engaging members are drivingly engaged with a drive arrangement associated with the other gear element and the first set of engaging members are in an unloaded state.

30. A first electric motor, a second electric motor, and a transmission system, the transmission system including a first input shaft drivingly coupled to the first electric motor, a second input shaft drivingly coupled to the second electric motor, an output member, a first gear train including a first gear element rotatably mounted on the first input shaft and a second gear element rotatably mounted on the second input shaft, the first gear element meshing with the second gear element, a second gear train including a third gear element rotatably mounted on the first input shaft and a fourth gear element rotatably mounted on the second input shaft, the third gear element meshing with the fourth gear element, and a first gear selector assembly configured to selectively lock the first and third gear elements for rotation with the first input shaft, and a second gear selector assembly configured to selectively lock the second and fourth gear elements for rotation with the second input shaft, the first gear selector assembly including first and second sets of engagement members that are movable independently of one another into and out of engagement with the first and third gear elements, the first gear selector assembly having the following modes: a mode that locks the gear elements for rotation with the first input shaft in forward and reverse torque directions, and a mode that locks the gear elements for rotation with the first input shaft in the forward torque direction and unlocks them in the reverse torque direction;and a mode in which the gear elements are locked for rotation with the first input shaft in the reverse torque direction and unlocked in the forward torque direction, the second gear selector assembly includes a first set of engaging members and a second set of engaging members that are movable independently of one another into and out of engagement with the second gear element and the fourth gear element, and the second gear selector assembly is configured to lock each of the second gear element and the fourth gear element for rotation with the second input shaft selectively from the following modes: a mode in which the gear elements are locked for rotation with the second input shaft in the forward torque direction and the reverse torque direction, a mode in which the gear elements are locked for rotation with the second input shaft in the forward torque direction and unlocked in the reverse torque direction, and a mode in which the gear elements are locked for rotation with the second input shaft in the reverse torque direction and unlocked in the forward torque direction.

31. The drive train of claim 30, wherein the first gear selector assembly includes a first set of engaging members and a second set of engaging members that are movable independently of each other.

32. 32. The drive train of claim 31, wherein the first and second sets of engagement members are configured such that when the first and second sets of engagement members select the first gear element and a braking force is transmitted, the first set of engagement members are in driving engagement with a drive arrangement associated with the first gear element and the second set of engagement members are in an unloaded state, and when a driving force is transmitted, the second set of engagement members are in driving engagement with a drive arrangement associated with the first gear element and the first set of engagement members are in an unloaded state.

33. 33. The drive train of claim 31 or 32, wherein the first and second sets of engagement members are configured such that when the first and second sets of engagement members select the third gear element, and in a drive force transmission condition, the first set of engagement members are in driving engagement with a drive arrangement associated with the third gear element and the second set of engagement members are in an unloaded condition, and when a braking force transmission condition, the second set of engagement members are in driving engagement with a drive arrangement associated with the third gear element and the first set of engagement members are in an unloaded condition.

34. 33. A drive train as claimed in any one of claims 30 to 32, wherein the second gear selector assembly includes a first set of engagement members and a second set of engagement members which are movable independently of each other.

35. 35. The drive train of claim 34, wherein the first and second sets of engagement members are configured such that when the first and second sets of engagement members select the second gear element, and a braking force is transmitted, the first set of engagement members are in driving engagement with a drive arrangement associated with the second gear element and the second set of engagement members are in an unloaded state, and when a driving force is transmitted, the second set of engagement members are in driving engagement with a drive arrangement associated with the second gear element and the first set of engagement members are in an unloaded state.

36. 36. The drive train of claim 34 or 35, wherein the first and second sets of engagement members are configured such that when the first and second sets of engagement members select the fourth gear element, and in a drive force transmission condition, the first set of engagement members are in driving engagement with a drive arrangement associated with the fourth gear element and the second set of engagement members are in an unloaded condition, and when a braking force transmission condition, the second set of engagement members are in driving engagement with a drive arrangement associated with the fourth gear element and the first set of engagement members are in an unloaded condition.

37. 37. The drive train of claim 1, wherein a maximum power rating of the first electric motor is different from a maximum power rating of the second electric motor.

38. A vehicle including a drive train according to any one of claims 1 to 37.

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