FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10; rule 13]
TITLE: “A TORQUE TRANSMISSION MECHANISM FOR AN ELECTRIC VEHICLE AND A METHOD THEREOF”
Name and Address of the Applicant:
TATA MOTORS LIMITED; an Indian company having a registered address at Bombay
House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra, India.
Nationality: Indian
The following specification particularly describes the invention and the manner in which it is to be performed.

5 TECHNICAL FIELD
Present disclosure, in general, relates to a field of electric automobiles. Particularly, but not exclusively, the present disclosure relates to powertrains in vehicles. Further, embodiments of the present disclosure relate to a torque transmission mechanism for an electric vehicle.
10
BACKGROUND OF THE DISCLOSURE
Typically, a transmission is coupled to a driving unit of a vehicle such as an engine and/or a motor. The transmission is used to receive and transmit speed and torque from the driving unit to drive wheels of the vehicle. The transmission is
15 synonymous with a drive head unit. Conventionally, in hybrid vehicles or electric
vehicles, a motor will be used as the driving unit coupled to the drive head unit and a differential. In electric vehicles, sometimes, the transmission, differential and the axle may be integrated as a single unit known as a transaxle. Further, a drive head unit layout and/or configuration varies based on torque and speed requirements of
20 the vehicle.
In general, existing torque transmission mechanisms generally involve two speed reduction layouts, three speed reduction layouts and so on. For example, a two speed reduction drive head unit has two sets of shift gear pairs at an output of the
25 motor that can be switched. The power output from the motor is transmitted to the
differential via a helical gear sets through the shift gear pairs. The drive head unit allows adjustment of the output gear ratio of the motor by switching shift gear pairs of different gears, to increase the driving torque and optimize the driving dynamics as well as performance of the vehicle. However, the existing drive head unites with
30 two speed reduction layout provide minimal speed reduction, whereas other drive
head units having wider speed reduction ratio are bulky. Further, with increase in speed reduction ratio, the layout of the drive head unit extends along lengthwise direction of the drive unit , in turn increasing offset between the drive head unit from axles of the wheels. Such an offset from the axle may generate a couple force
35 acting on the axle shaft and may shift centre of gravity of the vehicle due to

5 overhanging of the motor which is coupled to the drive head unit. Furthermore, such
layout configuration may lead to reduction in ground clearance of the vehicle, due to diameter of final driving gears in the drive unit.
The present disclosure is directed to overcome one or more limitations stated above
10 or any other limitations associated with the conventional mechanisms.
SUMMARY OF THE DISCLOSURE
One or more shortcomings of the prior art are overcome by a system as claimed and
additional advantages are provided through the method and the system as claimed
15 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.
20 In one non-limiting embodiment of the present disclosure a torque transmission
mechanism is disclosed. The torque transmission mechanism comprises a drive head unit having an input shaft rotatably disposed in the drive head unit and coupled to an electric motor. The drive head unit comprises a lay shaft disposed parallel to the input shaft and connected to the drive head unit, wherein the lay shaft is
25 rotatably coupled to the input shaft by one or more first gears to receive and transmit
torque from the electric motor through the input shaft. The drive head unit comprises an intermediate shaft rotatably disposable adjacent to the input shaft, and the intermediate shaft is rotatably coupled to the lay shaft by one or more second gears to receive and transmit torque from the lay shaft. The torque transmission
30 mechanism comprises an axle shaft rotatably disposed in a differential and
connectable to a plurality of wheels, wherein the axle shaft is coupled to the intermediate shaft by one or more third gears. The axle shaft is configured to receive torque from the intermediate shaft and transmit to the plurality of wheels.
35 In an embodiment, the torque transmission mechanism comprises a intermediate
bearing block disposable between the input shaft and the intermediate shaft.

5
In an embodiment, the intermediate bearing block is defined with a hub having a
first cavity and a second cavity on opposing sides of the hub, the first cavity is
configured to receive the input shaft and the second cavity is configured to receive
the intermediate shaft.
10
In an embodiment, each of the one or more first gears, the second gears and the
third gears comprises at least one driven gear and at least one driving gear.
In an embodiment, the drive head unit comprises a drive head housing configured
15 proximal to the differential.
In an embodiment, the torque transmission mechanism comprises a bracket removably connecting the drive head housing and the differential.
20 In another non-limiting embodiment, a method for transmission of torque in an
electric vehicle is disclosed. The method includes the steps comprising of receiving, by an input shaft, torque from an electric motor, wherein the input shaft is rotatably disposed in a drive head unit. Then, torque from the input shaft is received by a lay shaft, wherein the lay shaft is positioned parallel to the input shaft and connected to
25 the drive head unit and the lay shaft is rotatably coupled to the input shaft by one
or more first gears. The torque from the lay shaft is received by an intermediate shaft, wherein the intermediate shaft is rotatably disposable adjacent to the input shaft and is coupled to the lay shaft by one or more second gears. Finally, the torque from the intermediate shaft is received by an axle shaft, wherein the axle shaft is
30 connectable to a plurality of wheels of the electric vehicle and is coupled to the
intermediate shaft by one or more third gears to transmit the torque to the plurality of wheels.
In another non-limiting embodiment of the present disclosure, a vehicle is disclosed
comprising a chassis and a motor mounted on a portion of the chassis. The vehicle
35 further comprises a torque transmission mechanism connectable to a portion of the
chassis and coupled to the motor. The torque transmission mechanism comprises a

5 drive head unit having an input shaft rotatably disposed in the drive head unit and
coupled to an electric motor. The drive head unit comprises a lay shaft disposed parallel to the input shaft and connected to the drive head unit, wherein the lay shaft is rotatably coupled to the input shaft by one or more first gears to receive and transmit torque from the electric motor through the input shaft. The drive head unit
10 comprises an intermediate shaft rotatably disposable adjacent to the input shaft, and
the intermediate shaft is rotatably coupled to the lay shaft by one or more second gears to receive and transmit torque from the lay shaft. The torque transmission mechanism comprises an axle shaft rotatably disposed in a differential and connectable to a plurality of wheels, wherein the axle shaft is coupled to the
15 intermediate shaft by one or more third gears. The axle shaft is configured to receive
torque from the intermediate shaft and transmit to the plurality of wheels.
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
20 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
25 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
30 wherein like reference numerals represent like elements and in which:
Figure 1a is a perspective view of a torque transmission mechanism, in accordance with an embodiment of the present disclosure.
35 Figure 1b is an exploded view of the torque transmission mechanism, in accordance
with an embodiment of the present disclosure.

5
Figure 1c is a sectional view of the torque transmission mechanism, in accordance
with an embodiment of the present disclosure.
Figures 2a to 2e illustrates different views of a intermediate bearing block of the
10 torque transmission mechanism, in accordance with an embodiment of the present
disclosure.
Figure 3a is a sectional view of the torque transmission mechanism depicting a
multi-speed layout configuration, in accordance with an embodiment of the present
15 disclosure.
Figures 3b to 3e illustrate different sectional views of the torque transmission
mechanism in the multi-speed layout configuration depicting flow of transmission,
in accordance with an embodiment of the present disclosure.
20
Figure 4 is a flow diagram depicting a method for transmission of torque, in
accordance with an embodiment of the present disclosure.
The figures depict embodiments of the disclosure for purposes of illustration only.
25 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
30 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 alternative
35 falling within the scope of the disclosure.

5 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, 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
10 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 method.
Embodiments of the present disclosure discloses a torque transmission mechanism.
15 The torque transmission mechanism comprises a drive head unit having an input
shaft rotatably disposed in the drive head unit and coupled to an electric motor. The drive head unit comprises a lay shaft disposed parallel to the input shaft and connected to the drive head unit, wherein the lay shaft is rotatably coupled to the input shaft by one or more first gears to receive and transmit torque from the electric
20 motor through the input shaft. The drive head unit comprises an intermediate shaft
rotatably disposable adjacent to the input shaft, and the intermediate shaft is rotatably coupled to the lay shaft by one or more second gears to receive and transmit torque from the lay shaft. The torque transmission mechanism comprises an axle shaft rotatably disposed in a differential and connectable to a plurality of
25 wheels ,wherein the axle shaft is coupled to the intermediate shaft by one or more
third gears. The axle shaft is configured to receive torque from the intermediate shaft and transmit to the plurality of wheels. With such configuration, the torque transmission mechanism (100) may reduce couple forces generated at the axle beam assembly of the vehicle and shift of Centre of gravity of drive unit assembly towards
30 centre of the axle shaft (5). Further, such mechanism (100) may enhance ground
clearance of the vehicle, while providing a wide reduction ratio of the transmission.
The disclosure is described in the following paragraphs with reference to Figures 1
to 4. In the figures, the same element or elements which have same functions are
35 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

5 appreciate that the mechanism and the method as disclosed in the present disclosure
may be used in any vehicle including but not liming to commercial vehicles,
passenger vehicles, and the like. The system and the method of the present
disclosure may also be implemented in vehicles having manual transmission or
automatic transmission, for suitably maneuvering the vehicle without deviating
10 from the principles of the present disclosure.
Figures 1a to 1c refer to an exemplary embodiment of the present disclosure which illustrates a perspective view of a torque transmission mechanism (100) for an electric vehicle [not shown explicitly in figures]. The vehicle includes an electric
15 motor configured to drive the vehicle. The vehicle includes a differential (10)
coupled to the electric motor through a drive head unit (1). The differential (10) includes an axle shaft (5) rotatably disposed in the differential (10). The differential (10) is configured to receive and transmit torque from an electric motor to a plurality of wheels of the vehicle. The vehicle includes a torque transmission mechanism
20 (100) coupled between the electric motor and the differential (10) to receive the
torque from the electric motor and transmit the torque received to the differential (10) as can be seen in Figure 1a.
Further, the torque transmission comprises the drive head unit (1). The drive head
25 unit (1) includes a drive head housing (1a), coupled to a differential housing (1b).
The drive head unit (1) includes a motor receiving portion (1c) defined on the drive
head housing (1a) and configured to receive the electric motor. In the illustrative
embodiment, the motor receiving portion (1c) is defined proximal to the differential
housing (1b) as can be seen in Figure 1a and Figure 1b. The motor receiving portion
30 (1c) may include a cavity, a groove and a protrusion structured to receive the
electric motor. For the sake of explanation, the motor receiving portion (1c) is
depicted as a cavity as can be seen in Figure 1a. The drive head housing (1a) and
the differential housing (1b) may be defined along a lengthwise direction of the
drive head unit (1), while the motor receiving portion (1c) may be defined on a
35 lateral side of the drive head unit (1) as can be clearly seen in Figure 1b.

5 Referring again to Figures 1b and 1c, the drive head unit (1) includes an input shaft
(2) rotatably disposed in the drive head unit (1). The input shaft (2) is coupled to
the electric motor. In an embodiment, the input shaft (2) may be coupled to an
output shaft of the electric motor. In the illustrative embodiment, the input shaft (2)
is disposed adjacent to the motor receiving portion (1c). The input shaft (2) is
10 configured to receive the torque from the electric motor through the output shaft.
The drive head unit (1) may include a lay shaft (3) rotatably disposed in the drive head unit (1), connected to the drive head unit (1) and parallel to the input shaft (2). In the illustrative embodiment, the lay shaft (3) is disposed above the input shaft
(2) and proximal to the drive head housing (1a) as can be seen in Figure 1c. Further,
15 the lay shaft (3) extends along a widthwise direction of the drive head unit (1), while
the input shaft (2) extends up to a certain width of the drive head unit (1) as can be
seen in Figure 1c. In the illustrative embodiment, the input shaft (2) is shorter in
length compared to the lay shaft (3) to accommodate the input shaft (2) in a small
space of the drive head unit (1) and to make the drive head unit (1) compact. In an
20 embodiment, the lay shaft (3) is coupled to the input shaft (2) by one or more first
gears (6) to receive and transmit the torque from the input shaft (2). The lay shaft
(3) is configured to receive and transmit the torque from the electric motor received
through the input shaft (2). In an embodiment, the one or more first gears (6) may
include a first driving gear (61) mounted on the input shaft (2) and a first driven
25 gear (62) mounted on the lay shaft (3) as can be seen in Figure 1b. In an
embodiment, the one or more first gears (6) may be in constant mesh or may be meshed selectively based on requirement.
Further, the drive head unit (1) includes an intermediate shaft (4) rotatably disposed
30 adjacent to the input shaft (2). The intermediate shaft (4) is disposed below the lay
shaft (3) as can be seen in Figure 1c. The intermediate shaft (4) may be structured
to extend between the input shaft (2) and the drive head unit (1) along the widthwise
direction of the drive head unit (1). In an embodiment, the length of the input shaft
(2) and the intermediate shaft (4) may be similar or may be greater than the input
35 shaft (2) or less than the input shaft (2). In the illustrative embodiment, the length

5 of the lay shaft (3) may be equivalent or greater than length of the input shaft (2)
combined with length of the intermediate shaft (4) to make the drive head unit (1)
compact. For example, the length of the intermediate shaft (4) and the input shaft
(2) correspond to a split-shaft configuration equivalent to or slightly greater than
length of the lay shaft (3) as can be seen in Figure 1c.
10
Referring again to Figures 1b and 1c, the intermediate shaft (4) is rotatably coupled
to the lay shaft (3) by one or more second gears (7) to receive and transmit torque
from the lay shaft (3). The one or more second gears (7), like the one or more first
gears (6), may include a second driving gear (71) and a second driven gear (72),
15 where the second driving gear (71) is mounted on the lay shaft (3) and the second
driven gear (72) is mounted on the intermediate shaft (4). The intermediate shaft (4) is configured to receive torque from the lay shaft (3) through the one or more second gears (7) and transmit the torque to the differential (10) as can be clearly seen in Figure 1c. Further, the one or more third gears (8) may comprise a third
20 driving gear and a third driven gear as can be seen in Figure 1b, while the third
driving gear is mounted on the intermediate shaft (4) and the third driven gear is coupled to the differential (10) and further to the axle shaft (5) of the. The torque from the electric motor is received by the input shaft (2), by the lay shaft (3), by the intermediate shaft (4) and the axle shaft (5) sequentially and is transmitted to the
25 plurality of wheels as clearly indicated in Figure 1c. Such configuration of the input
shaft (2), the lay shaft (3) and the intermediate shaft (4) in the drive head unit (1) reduces the speed of the motor in three stages while maintaining compactness of the drive head unit (1). Furthermore, such configuration allows mounting of the electric motor proximal to the differential housing (1b) of the drive head unit (1)
30 and avoids generation of couple forces. In an embodiment, the drive head unit (1)
comprises a bracket [not shown in figures] removably connecting the drive head housing (1a) and the differential (10) for mounting of the electric motor and to further avoid generation of couple forces by fixedly coupling the drive head housing (1a) and the differential (10). In the illustrative embodiment, the bracket is fixedly
35 coupled between the drive head housing (1a) and the differential housing (1b).

5
Referring now to Figures 2a to 2c, the drive head unit (1) comprises a intermediate bearing block (9) disposable between the input shaft (2) and the intermediate shaft (4). The intermediate bearing block (9) is defined with a hub (91) having a first
10 cavity (9a) and a second cavity (9b). The intermediate bearing block (9) is defined
with the first cavity (9a) and the second cavity (9b) on opposing sides of the hub (91). The first cavity (9a) may be configured to receive the input shaft (2) and the second cavity (9b) may be configured to receive the intermediate shaft (4). In an embodiment, the first cavity (9a) and the second cavity (9b) are defined at an offset
15 with each other as can be seen in Figures 2d and 2e. The intermediate bearing block
(9) may be defined with a plurality of holes to be mounted on the drive head unit (1). The intermediate bearing block (9) may allow compact arrangement of the input shaft (2), the lay shaft (3), and the intermediate shaft (4) within the drive head unit (1). The position of the first cavity (9a) and the second cavity (9b) may be varied
20 based on design requirements of the drive head unit (1) and the same shall not be
considered a limitation. In an embodiment, the first cavity (9a) and the second cavity (9b) may be one of a through hole, a blind hole, and the like. In the illustrative embodiment, the first cavity (9a) and the second cavity (9b) are depicted to be through holes as can be seen in Figures 2d and 2e to allow positioning of the input
25 shaft (2) and the intermediate shaft (4) adjacently to ensure increased compactness
of the drive head unit (1).
Referring now to figure 3a, the drive head unit (1) may be a multi-speed drive head unit (1) having at least two pairs of gears between the input shaft (2) and the lay
30 shaft (3), and the lay shaft (3) and the intermediate shaft (4). The gears may be
selectively meshed based on speed and torque requirements of the vehicle. For example, the one or more first gears (6), the one or more second gears (7) may include a pair of high speed gears and a pair of low speed gears as can be seen in Figure 3a. For example, the one or more first gears (6) includes a first high speed
35 driven gear (62a), a first high speed driving gear (61a), a first low speed driving
gear (61b), and a first low speed driven gear (62b) coupled between the input shaft

5 (2) and the lay shaft (3). The one or more second gears (7) includes a second high
speed driven gear (72a), a second high speed driving gear (71a), a second low speed
driving gear (71b), and a second low speed driven gear (72b) coupled between the
lay shaft (3) and the intermediate shaft (4) as can be seen in Figure 3a. The drive
head unit (1) may thus provide four speeds to drive the vehicle by switching the one
10 or more first gears (6) and the one or more second gears (7). In an embodiment, the
one or more first gears (6) and the one or more second gears (7) may be engaged
and disengaged selectively by a clutch or a synchronizer. The clutch may be
selectively displaced by a shifter fork to engage the one or more first gears (6) and
the one or more second gears (7).
15
Referring now to Figures 3b and 3c, the drive head unit (1) provides a first speed
and/a first torque when the first high speed driving gear (61a) and the first high
speed driven gear (62a) are engaged and the second low speed driving gear (71b)
and the second low speed driven gear (72b) are engaged as can be seen in Figure
20 3b to transmit the torque from the input shaft (2) to the intermediate shaft (4)
through the lay shaft (3). The intermediate shaft (4) is coupled to the differential (10) by the one or more third gears (8) to transmit the first speed/torque to the axle and to the plurality of wheels. Further, the drive head unit (1) provides a second speed when the first high speed driving gear (61a) and the first high speed driven
25 gear (62a) are engaged and the second high speed driving gear (71a) and the second
high speed driven gear (72a) are engaged as can be seen in Figure 3c. The
intermediate shaft (4) is coupled to the differential (10) by the one or more third
gears (8) to transmit the second speed/torque to the axle and to the plurality of
wheels.
30
Referring now to Figures 3d and 3e, the drive head unit (1) provides a third speed
and/a third torque when the first low speed driving gear (61b) and the first low
speed driven gear (62b) are engaged, and the second low speed driving gear (71b)
and the second low speed driven gear (72b) are engaged as can be seen in Figure
35 3d. The intermediate shaft (4) is coupled to the differential (10) by the one or more
third gears (8) to transmit the third speed/torque to the axle and to the plurality of

5 wheels. Further, the drive head unit (1) provides a fourth speed when the first low
speed driving gear (61b) and the first low speed driven gear (62b) are engaged, and
the second high speed driving gear (71a) and the second high speed driven gear
(72a) are engaged as can be seen in Figure 3e. The intermediate shaft (4) is coupled
to the differential (10) by the one or more third gears (8) to transmit the fourth
10 speed/torque to the axle and to the plurality of wheels. In an embodiment, the
engagement and the number of gears in the one or more first gears (6), the one or
more second gears (7) is illustrated for explanatory purposes and the same shall not
be construed as a limitation, as the number of gears may be varied based on design
requirements of the drive head unit (1) and the vehicle.
15
Referring now to Figure 4 which illustrates a flow diagram depicting a method
(200) for transmission of torque in an electric vehicle.
The method (200) may describe in the general context of processor executable
20 instructions in the control unit. 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.
25 The order in which the method is described is not intended to be construed as a
limitation, and any number of the described method blocks may be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from the scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware,
30 software, firmware, or combination thereof.
At block 201, the input shaft (2) is configured to receive torque from the electric
motor, wherein the input shaft (2) is rotatably disposed in the drive head unit (1).
In an embodiment, the input shaft (2) may be coupled to the output shaft of the
35 electric motor. In the illustrative embodiment, the input shaft (2) is disposed
adjacent to the motor receiving portion (1c). The input shaft (2) is coupled to the

5 output shaft of the electric motor by one of a coupling, a set of gears and the like.
The input shaft (2) is configured to receive the torque from the electric motor through the output shaft.
At block 202, torque from the input shaft (2) is received by the lay shaft (3), wherein
10 the lay shaft (3) is positioned parallel to the input shaft (2) and connected to the
drive head unit (1). In an embodiment, the lay shaft (3) is coupled to the input shaft
(2) by one or more first gears (6) to receive and transmit the torque from the input
shaft (2). The one or more first gears (6) may include a first driving gear (61)
mounted on the input shaft (2) and a first driven gear (62) mounted on the lay shaft
15 (3). The lay shaft (3) is configured to receive and transmit the torque from the
electric motor received through the input shaft (2). The lay shaft (3) is rotatably
coupled to the input shaft (2) by one or more first gears (6). In the illustrative
embodiment, the lay shaft (3) is disposed above the input shaft (2) and proximal to
the drive head housing (1a). Further, the lay shaft (3) extends along the widthwise
20 direction of the drive head unit (1), while the input shaft (2) extends up to a certain
width of the drive head unit (1). In the illustrative embodiment, the input shaft (2)
is shorter in length compared to the lay shaft (3) to accommodate the input shaft (2)
in a small space of the drive head unit (1) and to make the drive head unit (1)
compact.
25
At block 203, the torque from the lay shaft (3) is received by an intermediate shaft
(4), wherein the intermediate shaft (4) is rotatably disposable adjacent to the input
shaft (2) and is coupled to the lay shaft (3) by one or more second gears (7). The
one or more second gears (7), like the one or more first gears (6), may include a
30 second driving gear (71) and a second driven gear (72), where the second driving
gear (71) is mounted on the lay shaft (3) and the second driven gear (72) is mounted on the intermediate shaft (4). The intermediate shaft (4) is configured to receive torque from the lay shaft (3) through the one or more second gears (7) and transmit the torque to the differential (10). The intermediate shaft (4) is disposed below the
35 lay shaft (3). The intermediate shaft (4) may be structured to extend between the
input shaft (2) and the drive head unit (1) along the widthwise direction of the drive
14

5 head unit (1). In an embodiment, the length of the input shaft (2) and the
intermediate shaft (4) may be similar or may be greater than the input shaft (2) or
less than the input shaft (2). In the illustrative embodiment, the length of the lay
shaft (3) may be equivalent or greater than length of the input shaft (2) plus the
length of the intermediate shaft (4) to make the drive head unit (1) compact.
10
At block 204, the torque from the intermediate shaft (4) is received by an axle shaft
(5) through the differential (10) of the vehicle. The axle shaft (5) is connectable to
a plurality of wheels of the electric vehicle and is coupled to the intermediate shaft
(4) by one or more third gears (8) to transmit the torque from the intermediate shaft
15 (4) to the plurality of wheels. Further, the one or more third gears (8) may comprise
a third driving gear and a third driven gear, while the third driving gear is mounted on the intermediate shaft (4) and the third driven gear is coupled to the axle shaft
(5) of the differential (10). In an embodiment, the third driven gear is coupled to a
side bevel gear of the differential (10) to transfer torque from the intermediate shaft
20 (4) to the axle shaft (5). In an embodiment, the input shaft (2), the lay shaft (3) and
the intermediate shaft (4) are disposed in the drive head unit housing (1a) through a plurality of bearings. The torque from the electric motor is received by the input shaft (2), by the lay shaft (3), by the intermediate shaft (4) and the axle shaft (5) sequentially and is transmitted to the plurality of wheels. Such configuration of the
25 input shaft (2), the lay shaft (3) and the intermediate shaft (4) in the drive head unit
(1) reduces the speed of the motor in three stages while maintaining compactness of the drive head unit (1).
In an embodiment, the configuration of the input shaft (2), the lay shaft (3) and the
30 intermediate shaft (4) of the torque transmission mechanism (100) allows mounting
of the electric motor proximal to the differential housing (1b) of the drive head unit (1) and avoids generation of couple forces.
In an embodiment, the configuration of drive head unit (1) corresponds to a three
35 stage speed reduction packaged in a two stage speed reduction configuration by

5 positioning the input shaft (2) and the intermediate shaft (4) in a split-shaft
configuration using the intermediate bearing block (9).
In an embodiment, the configuration of drive head unit (1) provides wider ratio
range in a very compact layout configuration.
10
With such configuration of torque transmission mechanism (100), the couple forces
are reduced & Shift in the Centre of gravity towards axle shaft Centre is achieved.
In an embodiment, the reduced final drive size across the complete wider ratio range
15 provides improved ground clearance of vehicle.
In an embodiment, the torque transmission mechanism (100) may eliminate or
reduce couple forces generated at the axle beam assembly of the vehicle and shift
of Centre of gravity of drive unit assembly towards centre of the axle shaft (5).
20
In an embodiment, diameter of final drive gear is reduced in the torque transmission
mechanism (100) which enhances ground clearance of the vehicle, while providing
a wide reduction ratio of the transmission.
25 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
30 clarity.
It will be understood by those within the art that, in general, terms used herein, and
especially in the appended claims are generally intended as “open” terms. It will
be further understood by those within the art that if a specific number of an
35 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

5 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
10 introductory phrases “one or more” or “at least one” and indefinite articles such as
“a” or “an”; 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
15 number. 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 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,
20 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 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,
25 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
30 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
35 the Markush group.

5
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
10 following claims.
Referral Numeral:

Component Referral numeral
Mechanism 100
Drive head unit 1
Drive head housing 1a
Differential housing 1b
Input shaft 2
Lay shaft 3
Intermediate shaft 4
Axle shaft 5
One or more first gears 6
First driving gear 61
First driven gear 62
First high speed driving gear 61a
First low speed driving gear 61b
First high speed driven gear 62a
First low speed driven gear 62b
One or more second gears 7
Second driving gear 71
Second high speed driving gear 71a
Second low speed driving gear 71b
Second high speed driven gear 72a
Second low speed driven gear 72b
Second driven gear 72
One or more third gears 8
Intermediate bearing block 9
Hub 91

First cavity 9a
Second cavity 9b
Motor receiving portion 1c
Differential 10
Method 200

5 We Claim:
1. A torque transmission mechanism (100) for an electric vehicle, comprising: a drive head unit (1), comprising:
an input shaft (2) rotatably disposed in the drive head unit (1)
and coupled to an electric motor;
10 a lay shaft (3) disposed parallel to the input shaft (2) and
connected to the drive head unit (1), wherein the lay shaft (3) is
rotatably coupled to the input shaft (2) by one or more first gears (6)
to receive and transmit torque from the electric motor through the
input shaft (2); and
15 an intermediate shaft (4) rotatably disposable adjacent to the
input shaft (2), and the intermediate shaft (4) is rotatably coupled to the lay shaft (3) by one or more second gears (7) to receive and transmit torque from the lay shaft (3);
an axle shaft (5) rotatably disposed in a differential (10) and
20 connectable to a plurality of wheels, wherein the axle shaft (5) is coupled to
the intermediate shaft (4) by one or more third gears (8), and
wherein the axle shaft (5) is configured to receive torque from the intermediate shaft (4) and transmit to the plurality of wheels.
25 2. The torque transmission mechanism (100) as claimed in claim 1, comprises
a intermediate bearing block (9) disposable between the input shaft (2) and the intermediate shaft (4).
3. The torque transmission mechanism (100) as claimed in claim 2, wherein
30 the intermediate bearing block (9) is defined with a hub (91) having a first
cavity (9a) and a second cavity (9b) on opposing sides of the hub (91), the
first cavity (9a) is configured to receive the input shaft (2) and the second
cavity (9b) is configured to receive the intermediate shaft (4).
35

5 4. The torque transmission mechanism (100) as claimed in claim 1, wherein
each of the one or more first gears (6), the second gears (7) and the third gears (8) comprises at least one driven gear and at least one driving gear.
5. The torque transmission mechanism (100) as claimed in claim 1, wherein
10 the drive head unit (1) comprises a drive head housing (1a) configured
proximal to the differential (10).
6. The torque transmission mechanism (100) as claimed in claim 5, comprises
a bracket removably connecting the drive head housing (1a) and the
15 differential (10).
7. A method (200) for transmission of torque in an electric vehicle, the method
(200) comprising:
receiving, by an input shaft (2), torque from an electric motor, wherein
20 the input shaft (2) is rotatably disposed in a drive head unit (1);
receiving, by a lay shaft (3), torque from the input shaft (2), wherein
the lay shaft (3) is positioned parallel to the input shaft (2) and connected to
the drive head unit (1), the lay shaft (3) is rotatably coupled to the input shaft
(2) by one or more first gears (6);
25 receiving, by an intermediate shaft (4), torque from the lay shaft (3),
wherein the intermediate shaft (4) is rotatably disposable adjacent to the input shaft (2) and is coupled to the lay shaft (3) by one or more second gears (7); and
receiving, by an axle shaft (5), torque from the intermediate shaft (4)
30 wherein the axle shaft (5) is connectable to a plurality of wheels of the
electric vehicle and is coupled to the intermediate shaft (4) by one or more third gears (8) to transmit the torque to the plurality of wheels.
8. A vehicle, comprising:
35 a chassis;
a motor mounted on a portion of the chassis;

5 a torque transmission mechanism (100) connectable to a portion of the
chassis and coupled to the motor, the mechanism (100) comprising: a drive head unit (1), comprising:
an input shaft (2) rotatably disposed in the drive head unit
(1) and coupled to an electric motor;
10 a lay shaft (3) disposed parallel to the input shaft (2) and
connected to the drive head unit (1), wherein the lay shaft (3) is
rotatably coupled to the input shaft (2) by one or more first gears
(6) to receive and transmit torque from the electric motor
through the input shaft (2); and
15 an intermediate shaft (4) rotatably disposable adjacent to
the input shaft (2), and the intermediate shaft (4) is rotatably coupled to the lay shaft (3) by one or more second gears (7) to receive and transmit torque from the lay shaft (3);
an axle shaft (5) rotatably disposed in a differential (10) and
20 connectable to a plurality of wheels ,wherein the axle shaft (5) is
coupled to the intermediate shaft (4) by one or more third gears (8), and
wherein the axle shaft (5) is configured to receive torque
from the intermediate shaft (4) and transmit to the plurality of
25 wheels.