Claims:1. A clutch-less transmission system (100) for an electric vehicle for seamless gear engagement, comprising:
a traction motor (1) connected to an input shaft (2), wherein the input shaft (2) accommodates a set of input gears (3, 4);
an output shaft (8) connectable to a differential unit (9), wherein the output shaft (8) accommodates a set of output gears (3’, 4’) to selectively mesh with a corresponding set of input gears (3, 4); and
a synchronizer (5), comprising:
a synchronizer ring (5b) connectable to the input shaft (2), wherein the synchronizer ring (5b) is adapted to selectively receive rotational speed from the input shaft (2); and
a slider sleeve (5a) selectively meshed to the synchronizer ring (5b), wherein the slider sleeve (5a) is selectively displaced by an actuator (6) to engage with at least one input gear of the set of input gears (3, 4) thereby, performing a seamless gear engagement to operate the vehicle, through at least one output gear of the set of output gears (3’, 4’).

2. The system as claimed in claim 1, wherein the synchronizer ring (5b) engages with the at least one input gear of the set of input gears (3, 4), when the actuator (6) selectively displaces the synchronizer (5) on the input shaft (2).

3. The system as claimed in claim 1, wherein the slider sleeve (5a) internally meshes with the synchronizer ring (5b), to adaptably mesh with the at least one input gear of the set of input gears (3, 4).

4. The system as claimed in claim 1 comprises an electronic control unit (7) communicatively interfaced with the traction motor (1) and the actuator unit (6), wherein the electronic control unit (7) is configured to:
receive rotational speed of the output shaft (8), to determine engagement of the synchronizer (5) with the at least one input gear of the set of input gears (3, 4);
determine rotational speed of the input shaft (2), wherein the rotational speed of the input shaft (2) is equal to rotational speed of the synchronizer (5);
compare rotational speed of the output shaft (8) with rotational speed of the synchronizer (5);
regulate rotational speed of the input shaft (2), based on the comparison; and
signal the actuator (6) to displace the synchronizer (5) to seamlessly engage with the at least one input gear of the set of input gears (3, 4).

5. The system as claimed in claim 4 comprises at least one sensor (10) mounted on a differential axle (9a), wherein the at least one sensor (10) generates an input signal to the electronic control unit (7), based on rotational speed of the differential axle (9a).

6. The system as claimed in claim 5, wherein the electronic control unit (7) determines a gear demand condition, based on the input signal received from the at least one sensor (10).

7. The system as claimed in claim 4, wherein the traction motor (1) is de-energized, by the electronic control unit (7), during engagement and disengagement of the synchronizer (5) from the at least one input gear.

8. The system as claimed in claim 4, wherein the traction motor (1) is regulated, by the electronic control unit (7), on comparing the rotational speed of the output shaft (8) with the rotational speed of the synchronizer (5), to mesh the synchronizer (5) with the at least one input gear of the set of input gears (3, 4).

9. The system as claimed in claim 4, wherein the traction motor (1) is controlled, by the electronic control unit (7), on meshing the synchronizer (5) with the at least one input gear, to transmit torque from the synchronizer (5) to the differential unit (9), by the corresponding set of output gears (3’, 4’).

10. The system as claimed in claim 4, wherein the actuator (6) is signaled, by the electronic control unit (7), to selectively displace the synchronizer (5) along the input shaft (2) such that,
the actuator (6) progressively engages the slider sleeve (5a) to mesh with the synchronizer ring (5b) and the at least one input gear of the set of input gears (3, 4), for seamless gear engagement.
11. The system as claimed in claim 10, wherein the synchronizer (5) is progressively displaced, by the actuator (6), based on the input signal generated by a position sensor (15) connected to the actuator (6).

12. A method for seamless gear engagement in a clutch-less transmission system (100) of an electric vehicle, comprising:
receiving, by an electronic control unit (7), rotational speed of an output shaft (8) connectable to a differential unit (9) of the vehicle, wherein the rotational speed of the output shaft (8) is used to determine engagement of a synchronizer (5) with at least one input gear of a set of input gears (3, 4);
determining, by the electronic control unit (7), rotational speed of an input shaft (2) connected to a traction motor (1), wherein the synchronizer (5) is connected to the input shaft (2) and rotational speed of the synchronizer (5) is equal to the rotational speed of the input shaft (2);
comparing, by the electronic control unit (7), the rotational speed of the output shaft (8) with the rotational speed of the synchronizer (5);
regulating, by the electronic control unit (7), the rotational speed of the input shaft (2) based on the comparison, for synchronizing the rotational speed of the synchronizer (5) with the at least one input gear of the set of input gears (3, 4); and
signaling an actuator (6), by the electronic control unit (7), to displace the synchronizer (5) to seamlessly engage with the at least one input gear of the set of input gears (3, 4).

13. The method as claimed in claim 10, wherein receiving, by the electronic control unit (7), comprises an input signal generated by at least one sensor (10) mounted on the differential axle (9a).

14. The method as claimed in claim 10, wherein determining, by the electronic control unit (7), a gear demand condition, based on the input signal received from the at least one sensor (10).

15. The method as claimed in claim 10, wherein regulating, by the electronic control unit (7), comprises selective accelerating and decelerating the traction motor (1) to regulate rotational speed of the input shaft (2).

16. The method as claimed in claim 10, wherein signaling the actuator (6), by the electronic control unit (7), comprises generation of a control signal to displace the synchronizer (5) on the input shaft (2), to engage with the at least one input gear of the set of input gears (3, 4).

17. The method as claimed in claim 10, wherein comparing and matching, by the electronic control unit (7), of rotational speed of the synchronizer (5) with rotational speed of the output shaft (8) is performed at neutral position of the synchronizer (5). , Description:TECHNICAL FIELD

Present disxclosure, in general, relates to the field of automobile engineering. Particularly, but not exclusively, the disclosure relates to a transmission system for a vehicle having multi-speed gearbox. Further, embodiments of the disclosure discloses a system and method for seamless gear engagement in a two-speed transmission system.

BACKGROUND OF THE DISCLOSURE
Generally, automobiles are provided with transmission system to supply power generated by an engine to the wheels. Conventional automobiles are equipped with either a manual transmission system or an automatic transmission system. In the manual transmission system, an operator may operate the vehicle by manually selecting different gears, based on different drive conditions. This selective engagement provides adequate torque and/or rotational speed to each wheel of the vehicle. Further, in an automatic transmission system, selection of different gears for engaging different gear ratios may be achieved by electronic signals, generated by various control units in the vehicle. However, each of the transmission systems, that is, the manual transmission system and the automatic transmission system, may be provisioned with a clutch mechanism, for assisting in a seamless engagement of different gears of the transmission system, for achieving requisite speed and/or torque. In addition, the clutch mechanism assists in disengagement of a driver shaft connected to an engine, from transmitting torque. This disengagement of driver shaft, by assistance from the clutch mechanism, may be achieved without causing much noise and vibration in the transmission mechanism.

Meanwhile, few other conventional vehicles which are partially and/or completely powered by electric drive systems such as electric motors or traction motors may be provisioned with the transmission system which may consist of a single-speed gearbox. The single-speed gearbox employs a set of gears which has a definite gear ratio, where the set of gears are adapted to selectively vary the speed and/or torque of the vehicle by varying the power supplied to the electric drive system. However, in the single-speed gearbox torque to speed ratios has an adverse relation like the torque applied to wheels of the vehicle may be reduced during varying the speed of the vehicle. The reduction of torque may render in the reduction of friction between each wheel and surface of travel of the vehicle, which may result in slippage thereby, lowering efficiency of travel of the vehicle. Additionally, the set of gears of the single-speed gearbox may be carefully selected in order to provide a linear torque to gain linear speed of the vehicle. Also, in order to assist the vehicle during uphill travel, sufficient torque needs to be produced from the electric motor or traction motor to serve the purpose. In order to suffice the torque demand, comparatively bulky electric motor or torque motor is used.

In addition, for electric vehicles or in case of hybrid vehicles when running in electric mode, it is required to maintain minimal payload in order to mitigate redundant load on the electric drive mechanism. This minimal payload may be achieved by minimizing a bulk of the transmission system, by eliminating and/or compensating for components. This makes the electric drive mechanism comparatively robust and light in weight. However, during operation of the electric drive mechanism to shift from one gear to another, the electric drive mechanism may be subjected to vibration and noise, due to an abrupt shift from instantons gear ratio to the requisite gear ratio.

The present disclosure is directed to overcome one or more limitations stated above.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of the prior art are overcome by a system and a method as claimed and additional advantages are provided through the system and the method as claimed in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the present disclosure, a clutch-less transmission system for an electric or hybrid vehicle for a seamless gear engagement is disclosed. The system comprises a traction motor, which is connected to an input shaft, where the input shaft accommodates a set of input gears. An output shaft is connectable to a differential unit and accommodates a set of output gears to selectively mesh with a corresponding set of input gears. Further, the system includes a synchronizer. The synchronizer comprises a synchronizer ring, which is connectable to the input shaft. The synchronizer ring is adapted to selectively receive rotational speed from the input shaft. The synchronizer further includes a slider sleeve, which is selectively meshed to the synchronizer ring. The slider sleeve is selectively displaced by an actuator to engage with at least one input gear of the set of input gears thereby, performing the seamless gear engagement to operate the differential unit of the vehicle, through at least one output gear of the set of output gears.

In an embodiment of the present disclosure, the synchronizer ring engages with the at least one input gear of the set of input gears, when the actuator selectively displaces the synchronizer on the input shaft.

In an embodiment of the present disclosure, the slider sleeve internally meshes with the synchronizer ring, to adaptably mesh with the at least one input gear of the set of input gears.

In an embodiment of the present disclosure comprises an electronic control unit, which is communicatively interfaced with the traction motor and the actuator unit. The electronic control unit is configured to receive rotational speed of the output shaft, to determine engagement of the synchronizer with the at least one input gear of the set of input gears. Further, the electronic control unit determines rotational speed of the input shaft, wherein the rotational speed of the input shaft is equal to rotational speed of the synchronizer. On determining, the electronic control unit compares the rotational speed of the output shaft with the rotational speed of the synchronizer. The electronic control unit then, regulates rotational speed of the input shaft, based on the comparison. In addition, the electronic control unit signals the actuator to displace the synchronizer, for seamless gear engagement with the at least one input gear of the set of input gears.

In an embodiment of the present disclosure comprises at least one sensor mounted on a differential axle, wherein the at least one sensor generates an input signal to the electronic control unit, based on rotational speed of the differential axle.

In an embodiment of the present disclosure, the electronic control unit determines a gear demand condition, based on the input signal received from the at least one sensor.

In an embodiment of the present disclosure, the traction motor is de-energized, by the electronic control unit, during engagement and disengagement of the synchronizer from the at least one input gear.

In an embodiment of the present disclosure, the traction motor is regulated, by the electronic control unit, on comparing the rotational speed of the output shaft with the rotational speed of the synchronizer, to mesh the synchronizer with the at least one input gear of the set of input gears.

In an embodiment of the present disclosure, the traction motor is accelerated or deceleretaed, by the electronic control unit, on meshing of the synchronizer with the at least one input gear, to transmit torque from the synchronizer to the differential unit, by the corresponding set of output gears.

In an embodiment of the present disclosure, the actuator is signaled, by the electronic control unit, to selectively displace the synchronizer along the input shaft. Further, the actuator progressively engages the slider sleeve to mesh with the synchronizer ring and the at least one input gear of the set of input gears, for seamless gear engagement.

In another non-limiting embodiment of the present disclosure, a method for seamless gear engagement in a clutch-less transmission system of an electric vehicle is disclosed. The method comprises steps of, receiving, by an electronic control unit, rotational speed of an output shaft connectable to a differential unit of the vehicle. The rotational speed of the output shaft is used to determine engagement of a synchronizer with at least one input gear of a set of input gears. Further, the electronic control unit determines rotational speed of an input shaft which is connected to a traction motor. Here, the synchronizer is connected to the input shaft and rotational speed of the synchronizer is equal to the rotational speed of the input shaft. In continuation, the electronic control unit compares the rotational speed of the output shaft with the rotational speed of the synchronizer. Upon comparing, the electronic control unit regulates the rotational speed of the input shaft, for synchronizing the rotational speed of the synchronizer with the at least one input gear of the set of input gears. Then, the electronic control unit signals an actuator to displace the synchronizer to seamlessly engage with the at least one input gear of the set of input gears.

In an embodiment, comparing and matching, by the electronic control unit, of rotational speed of the synchronizer with rotational speed of the output shaft is performed at neutral position of the synchronizer.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

Figure 1 is a schematic of a clutch-less transmission system for seamless torque transfer in a vehicle, in accordance with one embodiment of the present disclosure.

Figures 2a to 2f illustrates a sequence of schematic representations of a synchronizer, which is displaceable on an input shaft, in accordance with one embodiment of the present disclosure.

Figure 3 is a flowchart, which illustrates a method of seamless transfer of torque in the clutch-less transmission system, in accordance with some embodiment of the present disclosure.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the system and method illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

While the embodiments in the disclosure are subject to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the figures and will be described below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, assembly, mechanism, system, method that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or mechanism.

Embodiment of the present disclosure discloses a clutch-less transmission system for an electric vehicle for seamless gear engagement. The system includes a traction motor, which is connected to an input shaft. The input shaft is configured to accommodate a set of input gears. Further, an output shaft is connectable to a differential unit, and accommodates a set of output gears to selectively mesh with a corresponding set of input gears. The system further includes a synchronizer. The synchronizer comprises a synchronizer hub which is connectable to the input shaft. A synchronizer ring mounted to a side face of the synchronizer hub is adapted to selectively receive rotational speed from the input shaft. The synchronizer is further provisioned with a slider sleeve, which is internally meshed to the synchronizer ring. Additionally, the slider sleeve is selectively displaced by an actuator to engage with at least one input gear of the set of input gears. Here, the synchronizer ring engages with the at least one input gear of the set of input gears, when the actuator selectively displaces the synchronizer on the input shaft to complete a path for transferring the torque from the traction motor to the differential unit of the vehicle.

Further, an electronic control unit is provisioned in the system, where the electronic control unit is communicatively interfaced with the traction motor and the actuator unit. The electronic control unit is configured to determine rotational speed of the output shaft. Further, the electronic control unit determines rotational speed of the input shaft, wherein the rotational speed of the input shaft is equal to rotational speed of the synchronizer. On determining, the electronic control unit compares the rotational speed of the output shaft with the rotational speed of the synchronizer. The electronic control unit then, regulates rotational speed of the input shaft, based on the comparison. In addition, the electronic control unit signals the actuator to displace the synchronizer to seamlessly engage with the at least one input gear of the set of input gears. Here, a person skilled in the art may appreciate that, the comparison between the rotational speed of the at least one input gear of the set of input gears which may be engaged with the at least one output gear of the set of output gears may be also considered by the electronic control unit for operating the synchronizer, via the actuator. Additionally, the person skilled in the art would recognize that, for such comparisons, gear ratios between the engaged gears are to be considered by the electronic control unit, for speed comparison and further operations.

The disclosure is described in the following paragraphs with reference to Figures 1 to 3. In the figures, the same element or elements which have same functions are indicated by the same reference signs. It is to be noted that, the vehicle is not illustrated in the figures for the purpose of simplicity. One skilled in the art would appreciate that the system and the method as disclosed in the present disclosure can be used in any vehicle including but not limiting to a passenger car, a light-duty vehicles or any other vehicle. Also, the system and the method may be employed in vehicles which are partially and/or completely driven by electric motors. Here, a person skilled in the art would recognize that the number of gears on the input shaft and the output shaft may be varied, to achieve a wide range of speed and/or torque generated by the traction motor, to drive the vehicle. Hence, for the sake of simplicity in explanation of the system, in the exemplary embodiment of the present disclosure, a two-speed gearbox having two input gears and corresponding output gears are illustrated in the figures.

Referring to Figure 1 which is an exemplary embodiment of the present disclosure illustrating a schematic of a clutch-less transmission system (100), for seamless gear engagement in a vehicle [not shown in figures]. The clutch-less transmission system (100), herein also referred to as “system”, according to the exemplary embodiment includes, a traction motor (1), where the traction motor (1) is employed to drive the vehicle. The traction motor (1) is connected to a power supply [not shown in figures] such as, but not limited to, a battery (14), through which the traction motor (1) gains power, for generating torque. Further, the torque from the traction motor (1) may be transmitted to each wheel (11) of the vehicle.

In an exemplary embodiment, the traction motor (1) is connected to an input shaft (2), through which torque generated by the traction motor (1) is supplied. Further, the input shaft (2) accommodates a set of input gears (3, 4), where the set of input gears (3, 4) mesh with a corresponding set of output gears (3’, 4’). The set of output gears (3’, 4’) are mounted on an output shaft (8), where the output shaft (8) may either be co-axial or be parallel to the input shaft (2). However, in an exemplary embodiment, the output shaft (8), accommodating the set of output gears (3’, 4’), is positioned parallel to the input shaft (2). In addition, the output shaft (8) is connected to a differential unit (9), where the differential unit (9) is coupled to each of the wheels (11), to receive the torque transferred from the output shaft (8) via a differential axle (9a).

Further, the set of input gears (3, 4) and the set of output gears (3’, 4’) are selected such that, each of the at least one input gear (3 and 4) is meshed with corresponding each of the at least one output gear (3’ and 4’) synchronously, and assists in regulating the torque supplied from the input shaft (2) to each of the wheels (11) of the vehicle. In an embodiment, the set of input gears (3, 4) are mounted on the input shaft (2) on a bearing (12a) such that, no torque is transmitted through the set of input gears (3, 4) until a mesh is established between at least one input gear of the set of input gears (3, 4) and the input shaft (2). However, the set of output gears (3’, 4’) are rigidly connected to the output shaft (8), and upon receiving the torque, the set of output gears (3’, 4’) rotates the output shaft (8).

The system further includes a synchronizer (5), including a hub [not shown in figures], rigidly connected to the input shaft (2). Further, the synchronizer (5) is positioned between each input gear of the set of input gears (3, 4). The synchronizer (5) includes a synchronizer ring (5b) and a slider sleeve (5a), as best shown in Figures 2a to 2f. The synchronizer ring (5b) and the slider sleeve (5a) are co-axially mounted on synchronizer hub such that, the synchronizer ring (5b) is adaptably traversed within the slider sleeve (5a). In addition, the slider sleeve (5a) is adapted to be laterally displaced in-between the synchronizer hub and the set of input gears (3, 4). This lateral displacement of the synchronizer ring (5b) and the slider sleeve (5a) assists in engaging and disengaging the synchronizer (5) from at least one input gear of the set of input gears (3, 4). Here, it may be noted that the synchronizer ring (5a) is connected to the input shaft (2) via the synchronizer hub, and hence, rotates along with the input shaft (2). Due to this connection, the rotational speed of the synchronizer ring (5b), and in-turn the rotational speed of the synchronizer (5) may be construed to possess equal rotational speed as that of the input shaft (2). However, the slider sleeve (5a) may be configured to independently traverse with reference to the synchronizer ring (5b), when the synchronizer (5) is disengaged from the at least one input gear of the set of input gears (3, 4).

In addition, the synchronizer ring (5b) and the slider sleeve (5a) are provisioned with a plurality of teeth (13). The plurality of teeth (13) may be circumferentially positioned on the synchronizer ring (5b) to form an external mesh, while the plurality of teeth (13) may be positioned on the slider sleeve (5a) to form an internal mesh. Additionally, the plurality of teeth (13) of the slider sleeve (5a) may be positioned such that, the plurality of teeth (13) of the slider sleeve (5a) may be allowed to mesh and traverse across the synchronizer ring (5b), in order to mesh with the at least one input gear (3 or 4). Upon meshing the slider sleeve (5a) with the at least one input gear of the set of input gears (3, 4), the synchronizer (5) imparts rotational speed which is equal to that of the input shaft (2).

The synchronizer (5) is connected to an actuator (6), which assists in selective displacement of the synchronizer (5) on the input shaft (2). The actuator (6) may be electronically controlled to displace the synchronizer (5) between the set of input gears (3, 4) to assist in engaging and disengaging the synchronizer (5) from the at least one input gear of the set of input gears (3, 4). On engaging the synchronizer (5) with the at least one input gear of the set of input gears (3. 4), torque from the input shaft (2) is transferred to the at least one input gear of the set of input gears (3, 4). As an example, when the synchronizer (5) engages with the at least one input gear of the set of input gears (3, 4), torque from the input shaft is transferred to at least one output gear of the set of output gear (3’, 4’). In addition, the connection between the at least one input gear of the set of input gears (3, 4) and the synchronizer (5) establishes a path for torque transfer in the system (100) thereby imparting rotational speed to the output shaft (8), and in-turn to each of the wheels (11), through the differential unit (9).

In an exemplary embodiment, the actuator (6) is connected to an electronic control unit (7), where the electronic control unit (7) assists the actuator (6) to displace the synchronizer (5) on the input shaft (2). The electronic control unit (7), herein referred to as ECU, determines a condition at which the synchronizer (5) is required to be displaced by the actuator (6). The condition, which is also termed as “gear demand condition”, that is required to be determined by the ECU (7), may be provided by at least one sensor (10), mounted on the differential axle (9a). In an exemplary embodiment, the at least one sensor (10) senses the rotational speed of the differential axle (9a), in order to indicate the gear demand condition. However, it may be noted that the gear demand condition may also arise due to conditions including, but not limited to, the gradient of traveling surface, the rotational speed, the slip experienced by each wheel (11), and the like. Further, the at least one sensor (10) is employed to periodically generate an input signal pertaining to the rotational speed of the differential axle (9a) thereby, instantaneously assisting the ECU (7) to determine the gear demand condition. In an embodiment, the comparison between the rotational speed of the at least one input gear of the set of input gears (3, 4) which may be engaged with the at least one output gear of the set of output gears (3’, 4’) may be also considered by the electronic control unit (7) for operating the synchronizer (5), via the actuator (6). Additionally, the person skilled in the art would recognize that, for such comparisons, gear ratios between the engaged gears are to be considered by the electronic control unit (7), for speed comparison and further operations. Here, it may be noted that, due to direct coupling of the output shaft (8) and the differential unit (9), there may be negligible losses in torque transfer as differential gear ratio may be considered, thereby the rotational speed of the output shaft (8) and the output of the differential unit (9), via the differential axle (9a), remains substantially equal.

Further, based on the input signal received from the at least one sensor (10), the ECU (7) determines the rotational speed of the output shaft (8). The ECU (7) may also determine the rotational speed of the input shaft (2), by monitoring the power supplied to the traction motor (1), which results in determining the speed of the traction motor (1) and in-turn that of the input shaft (2). Then, the ECU (7) compares the rotational speed of the output shaft (8) with the rotational speed of the input shaft (2) to determine the gear demand condition, where the ECU compares the vehicle speed based on the upshift and downshift threshold to generate the gear demand. Once the gear demand is established by the ECU (7), then based on the comparison of the rotational speeds, the ECU (7) regulates the speed of input shaft (2) by selectively decelerating and/or accelerating the traction motor (1). Here, a person skilled in the art would recognize that the selective decelerating and/or accelerating of the traction motor (1) may be performed by regulating the power supplied to the traction motor (1). Further, it may also be noted that the power supplied to the traction motor (1) may be a factor depending either on supplied voltage, supplied current, or both.

For example, when the synchronizer (5) is initially engaged with the at least one input gear of the set of input gears (3, 4), the ECU (7) may temporarily cut-off power to the traction motor (1), in order to reduce the rotational speed of the input shaft (2). On temporarily cutting-off the power to the traction motor (1) [or also referred to as idle mode of the traction motor (1)], the ECU (7) then, communicates to the actuator (6), to disengage the synchronizer (5) from the at least one input gear of the set of input gears (3, 4). The cutting-off of power to the traction motor (1) assists by easing in the disengagement of the synchronizer (5), by the actuator (6). In continuation, if the synchronizer (5), disengaged from the at least one input gear, is to mesh with the at least one input gear of the set of input gears (3, 4), then the ECU (7) selectively decelerates and/or accelerates the traction motor (1), to regulate the speed of the input shaft (2). At this point, the synchronizer (5) is at a neutral position (N). Here, the selective deceleration and/or acceleration of the traction motor (1) is performed in order to compensate the rotational speed of the input shaft (2) with respect to the rotational speed of the output shaft (8). In an embodiment of the present disclosure, the selective deceleration and/or acceleration of the traction motor (1), by the ECU (7), may be termed as “speed control mode” of the system 100. However, it may be noted that, the ECU (7) regulates the rotational speed of the input shaft (2), based on the comparison of the rotational speed of the input shaft (2) with the input signal pertaining to the rotational speed of the output shaft (8), which is transmitted by the at least one sensor (10).

Upon regulation of the rotational speed of the input shaft (2), the ECU (7) signals the actuator (6) to selectively displace the synchronizer (5) in order to engage with the at least one input gear of the set of input gears (3, 4). On displacement of the synchronizer (5) on the input shaft (2), a position sensor (14) provided on an actuator shaft [not shown in figures]generates a communication signal to the ECU (7) pertaining to an instantaneous position of the synchronizer (5). This communication signal, from the position sensor (15), pertaining to the instantaneous position of the synchronizer (5) and enables the ECU (7) to determine seamless engagement and disengagement of the at least one input gear of the set of input gears (3, 4), thereby assisting the ECU (7) to affirm satisfaction of the gear demand. On affirmation of engagement and disengagement between the synchronizer (5) and the at least one input gear of the set of input gears (3, 4), the ECU (7) selectively accelerates the traction motor (1) in order to transmit torque to each of the wheels (11) of the vehicle.

Referring now to Figures 2a to 2f, which illustrates a sequence of schematic representations of the synchronizer (5). Further, each of the figures illustrates selectively displacement of the synchronizer (5) on the input shaft (2). It may be noted that the selective displacement is referred to a reference direction for traversing of the synchronizer (5) on the input shaft (2), in order to select between the set of input gears (3, 4), for engagement. Here, the displacement of the synchronizer (5) is illustrated with reference to a first axis (A-A), which is axis (A-A) of the input shaft (2). Also, the synchronizer (5) is displaced by the actuator (6) [as shown in Figure 1] upon receiving the communication signal from the ECU (7), which establishes the gear demand condition. It may be noted that the communication signal transmitted by the ECU (7) indicates the reference direction and length of displacement of the synchronizer (5) on the input shaft (2), in order to engage with the at least one input gear of the set of input gears (3, 4), for satisfying the gear demand condition.

For example, a condition where the ECU (7) signals the actuator (6) to displace the synchronizer (5) towards at least one input gear of the set of input gears (3, 4) with reference to a second axis (B-B). In Figures 2a to 2f, it may be noted that the second axis (B-B) may be considered as a reference to the neutral point (N) on the input shaft (2), from which the synchronizer (5) may be displaced. Also, the ECU (7) instantaneously cuts-off power to the traction motor (1) during disengagement, in order to position the synchronizer (5) at the neutral point (N) on the input shaft (2) so that, minimal resistance is offered by the synchronizer (5) during the displacement by the actuator (6) on the input shaft (2).

The ECU (7) regulates the rotational speed of the input shaft (2), based on the comparison of the rotational speed of the input shaft (2) with the input signal pertaining to the rotational speed of the output shaft (8), which is transmitted by the at least one sensor (10). In an embodiment of the present disclosure, the speed comparison between the speed of input shaft (2) and the speed of output shaft (8) may also be termed as “active synchronization”. The ECU (7) then, transmits the communication signal to the actuator (7). Upon receiving the communication signal from the ECU (7), the actuator (6) displaces the synchronizer (5) on the input shaft (2) with reference to the second axis (B-B). The synchronizer ring (5b), with the synchronizer (5), is displaced towards the at least one input gear of the set of input gears (3, 4), through a cone geared ring (12b).

Referring now to Figure 2b, the synchronizer ring (5b), on engagement with the cone geared ring (12b) of the at least one input gear of the set of input gears (3, 4), is restricted from further displacement on the input shaft (2). Meanwhile, the slider sleeve (5a) is progressively displaced on the input shaft (2) such that, the slider sleeve (5a) approaches the synchronizer ring (5b), as shown in Figure 2c. However, as the plurality of teeth (13) of the slider sleeve (5a) is required to internally mesh with the plurality of teeth (13) of the synchronizer ring (5b), there may be inertial and/or frictional resistance experienced by the slider sleeve (5a), during the engagement. This inertial and/or frictional resistance may be due to a virtue of the rotational speed of the synchronizer ring (5b) thereby causing a first knock between the synchronizer ring (5b) and the slider sleeve (5a), during the engagement. It may be noted that, the first knock caused due to the inertial and/or frictional resistance may be negligible, as the plurality of teeth (13) of the slider sleeve (5a) and the plurality of teeth (13) of the synchronizer ring (5b) may be designed to coherently mesh on engagement. Also, on experiencing the first knock, the slider sleeve (5a) is progressively displaced by the actuator (6) to the synchronizer (5) and/or the at least one gear of the set of input gears (3, 4) with which the synchronizer ring (5b) is engaged.

The slider sleeve (5a) on experiencing the first knock, is further displaced by the actuator (6), where the synchronizer ring (5b) internally meshes with the slider sleeve (5a), as shown in Figure 2d. At this juncture, the slider sleeve (5a) engages the synchronizer ring (5b), thereby rotating the synchronizer ring (5b) at a speed equal to the rotational speed of the input shaft (2). Further, the slider sleeve (5a) is displaced by the actuator (6) to traverse across the synchronizer ring (5b) therein. On traversing across the synchronizer ring (5b), the slider sleeve (5a) engages the at least one input gear of the set of input gears (3, 4). As disclosed above, the slider sleeve (5a) experiences a second knock on encountering with the at least one input gear of the set of input gears (3, 4), as shown in Figure 2e.

On experiencing the second knock, the rotational speed of the slider sleeve (5a), and in-turn the rotational speed of the synchronizer (5), is compensated to match the rotational speed of the at least one input gear of the set of input gears (3, 4), by aligning the plurality of teeth (13) of the slider sleeve (5a) with the plurality of teeth provisioned in the at least one input gear of the set of input gears (3, 4). Nonetheless, on experiencing the second knock, the rotational speed of the at least one input gear may also be compensated to match the rotational speed of the synchronizer (5). In continuation, the slider sleeve (5a) may be further displaced by the actuator (6) to complete meshing of the slider sleeve (5a) with the at least one input gear of the set of input gears (3, 4), as shown in Figure 2f. It may be noted that, on meshing, the slider sleeve (5a) transfers the torque from the input shaft (2) to the at least one input gear of the set of input gears (3, 4), thereby driving the output shaft (8). Upon engaging the synchronizer (5) with the at least one input gear of the set of input gears (3, 4), the position sensor (15) constantly transmits a feedback signal to the ECU (7), indicating the instantaneous position of the synchronizer (5) on the input shaft (2). Based on the instantaneous position of the synchronizer (5) on the input shaft (2), the ECU (7) affirms engagement between the synchronizer (5) and the at least one input gear. On affirmation of engagement between the synchronizer (5) and the at least one input gear (3 or 4), the ECU (7) selectively accelerates the traction motor (1). This enables the system (100) to provide mobility with varying torque and/or speed required, for the vehicle to traverse. In an embodiment, the electronic control unit, at neutral position of the synchronizer, compares and matches the rotational speed of the synchronizer with rotational speed of the output shaft.

Turning now to Figure 3, which is an exemplary embodiment of the present disclosure illustrating a flowchart of a method (200) of seamless gear engagement in the system (100). The method (200) may be employed in the vehicles which are either completely and/or partially driven by the electric motor, such as the traction motor (1).

The method (200) may be described in the general context of processor-executable instructions. Generally, the executable instructions may include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform particular functions or implement particular abstract data types.

The order in which the method (200) is described is not intended to be construed as a limitation, and any number of the described method blocks (201-208) may be combined in any order to implement the method (200). Additionally, individual blocks may be added or deleted from the methods, without departing from the scope of the subject matter described herein. Furthermore, the method (200) can be implemented in any suitable hardware, software, firmware, or combination thereof.

At block 201, the ECU (7), determines the position of the synchronizer (5). Here, the position of the synchronizer (5) may be at least one of, at neutral point (N) or engaged with the at least one input gear of the set of input gears (3, 4). On determining the position of the synchronizer (5), the ECU (7) evaluates the rotational speed of the output shaft (8).

The ECU (7) constantly determines the rotational speed of the output shaft (8) in order to monitor the gear demand condition, as in block 202. The gear demand condition may be established. Once the gear demand condition is established by the ECU (7), the ECU (7) generates the communication signal to the actuator (6), to displace the synchronizer (5) to the neutral point (N). It may be noted that the position sensor (15) connected to the actuator (6) constantly generates the input signal to the ECU (7), indicating instantaneous position of the synchronizer (5). Further, when the synchronizer (5) is in mesh with the at least one input gear of the set of input gears (3, 4) then, the ECU (7) communicates to the actuator (6) to displace the synchronizer (5). This displacement of the synchronizer (5) from the at least one input gear of the set of input gears (3, 4) to the neutral point (N) thereby, preventing transfer of torque from the input shaft (2) to the output shaft (8) as in block 203.

At block 204, the ECU (7) receives the input signal provided by the at least one sensor (10). Here, it may be noted that the at least one sensor (10) constantly transmits the input signal pertaining to the instantaneous condition of each of the wheels (11) [i.e. the rotational speed of each of the wheels] thereby assisting the ECU (7) to determine the gear demand condition of the vehicle. The input signal may indicate parameters such as, but not limited to, the gradient of traveling surface, the rotational speed, the slip experienced by each wheel (11), and the like.

Upon receiving the input signal from the at least one sensor (10), at block 205, the ECU (7) determines the rotational speed of the input shaft (2). Here, the rotational speed of the input shaft (2) may be determined by one or more parameter such as, but not limited to, the power supplied to the traction motor (1), one or more sensors positioned on the input shaft (2), and the like. The ECU (7) on determining the corresponding rotational speed of the input shaft (2) and the output shaft (8), the ECU (7) then, compares the respective rotational speeds, in order to establish the gear demand condition, as in block 206.

In an embodiment, the comparison between the rotational speed of the input shaft (2) and the rotational speed of the output shaft (8), by the ECU (7), may be performed with reference to the gear ratio set between the at least one input gear of the set of input gears (3, 4) with the corresponding output gear of the set of output gears (3’, 4’). In other words, the rotational speed of the synchronizer (5) is compared with the speed of the target gear of the set of output gears (3’, 4’) to be engaged therewith. Here, the ECU (7) may be programmed to compare the rotational speed of the output shaft (8) with respect to a range of rotational speed, which is set for the gear ratio of the least one input gear with the corresponding output gear.

Further, at block 207, when the ECU (7) compares the rotational speed of the input shaft (2) and the corresponding rotational speed of the output shaft (8) to establish the gear demand, the ECU (7) regulates the rotational speed of the input shaft (2), in order to satisfy the gear demand. It may be noted that the ECU (7) regulates the speed of input shaft (2), by selectively decelerating and/or accelerating the traction motor (1), whereby the ECU (7) regulates the rotational speed of the traction motor (1) in a speed control mode, to accelerate or decelerate the rotational speed of the at least input gear of the set of output gears (3, 4) in order to engage with the target gear of the set of output gears (3’, 4’), thereby leading to active synchronization.

In an embodiment, upon the comparison, when the rotational speed of the output shaft (8) is lower than the rotational speed of the input shaft (2), by considering of the gear ratios therebetween, then, the ECU (7) decelerates the traction motor (1). The ECU (7), thus, compensates by decelerating the traction motor (1) thereby, decreasing the rotational speed of the input shaft (2) to match the rotational speed of the output shaft (8). In an exemplary embodiment, upon the comparison, when the rotational speed of the output shaft (8) is higher with respect than the rotational speed of the input shaft (2) , by considering of the gear ratios therebetween, then, the ECU (7) selectively accelerating the traction motor (1). The ECU (7), thus, compensates by selectively accelerating the traction motor (1) thereby, increasing the rotational speed of the input shaft (2) to match the rotational speed of the output shaft (8). This eases the system (100) to shift from the lower gear ratio to the higher gear ratio thereby, delivering suitable speed to the output shaft (8).

In an exemplary embodiment, the ECU (7) tends to shift from one gear ratio to another gear ratio by signaling the actuator (6) to displace the synchronizer (5) to engage with the at least one input gear (2 or 4), as in block 208, to achieve the gear demand condition. The displacement of the synchronizer (5), by the actuator (6), to engage the at least one input gear of the set of input gears (3, 4), is explained in Figures 2a to 2f. Upon engagement of the synchronizer (5) with the at least one input gear of the set of output gears (8), the actuator (6) transmits a feedback signal to the ECU (7), indicating the instantaneous position of the synchronizer (5) on the input shaft (2). Based on the instantaneous position of the synchronizer (5) on the input shaft (2), the ECU (7) affirms shift in the gear ratio thereby, satisfying the gear demand condition. Furthermore, the ECU (7) selectively accelerates the traction motor (1) in order to transmit adequate torque and speed to the at least one input gear of the set of input gears (3, 4) that is seamlessly engaged with the synchronizer (5).

Once the seamless gear engagement is performed, the ECU (7) reciprocates the methods mentioned in blocks 201 and 202 in order to operate the vehicle.

In some embodiments, the at least one sensor (10) may be a speed sensor, a gradient sensor, a voltage sensor, and the like. In an embodiment, the at least sensor (10) may be a speed sensor, which is at least one of a mechanical speed sensor, an electronic speed sensor, an electromechanical speed sensor, a magnetic sensor, and the like. Further, positioning of the at least one sensor (10) may not be limited to the differential axle (9a) and may be positioned based on convenience and requirement. For example, at least one sensor (10) may also be mounted on the output shaft (8), on a wheel hub of each of the wheels (11), and the like.

In some embodiments, the actuator (6) may be a proportional–integral–derivative (PID) controller, proportional–integral (PI) controller. Further, the actuator (6) may also be configured to an electromechanical actuator, which may be including, but not limited to, linear variable displacement transducer (LVDT), a piezoelectric actuator, and the like, to displace the synchronizer (5).

In some embodiments, the ECU (7), the actuator (6), the at least one sensor (10) and the traction motor (1) may be powered by a single power source, such as the battery (14). The battery (14) may be a Lithium-ion battery, a solar battery, a super capacitor, and the like.

In some embodiments, the ECU (2) may be a centralized control unit of the vehicle or may be a dedicated control unit to the system associated with the centralized control unit of the vehicle. The ECU (2) also be associated with other control units such as Transmission Control Unit and brake control unit. The ECU (2) may include specialized processing units such as integrated system (bus) controllers, memory management control units, floating point units, graphics processing units, digital signal processing units, etc. The processing unit may include a microprocessor, such as AMD Athlon, Duron or Opteron, ARM’s application, embedded or secure processors, IBM PowerPC, Intel’s Core, Itanium, Xeon, Celeron or other line of processors, and the like. The ECU (2) may be implemented using the mainframe, distributed processor, multi-core, parallel, grid, or other architectures. Some embodiments may utilize embedded technologies like application-specific integrated circuits (ASICs), digital signal processors (DSPs), Field Programmable Gate Arrays (FPGAs), microcontroller, and the like.

EQUIVALENTS

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

REFERAL NUMERALS:
Particulars Numerical
Traction motor 1
Input shaft 2
Input gears 3, 4
Output gears 3’, 4’
Synchronizer 5
Slider sleeve 5a
Synchronizer ring 5b
Actuator 6
Electronic control unit 7
Output shaft 8
Differential unit 9
Differential axle 9a
At least one sensor 10
Wheel 11
Bearing 12a
Cone geared rings 12b
Plurality of teeth 13
Battery 14
Position sensor 15
System 100
Method steps 201-208