DESC:FORM 2

THE PATENTS ACT, 1970

[39 OF 1970]
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION

(Section 10; Rule 13)

AN INTEGRATED SYSTEM OF 5 SPEED MANUAL TRANSMISSION WITH AUTOMATIC TRANSFER CASE

AVTEC Ltd.
Pithampur Industrial Area, Sector III,
Pithampur, Sagore 454774,
Dist Dhar (M.P.), INDIA
An Indian Company

The following Specification particularly describes the invention and the manner in which it is to be performed

FIELD OF INVENTION
The present invention generally relates to automobiles, and more particularly relates to a system with integrated 5 speed manual transmission and automatic transfer case.

BACKGROUND OF THE INVENTION
The conventional design is transcribed and reinforced into integrated compact design. The conventional transmission has been used in All-wheel drive (AWD) vehicles that has independent transfer case separately attached (Figure 1).

According to the prior art, to make a vehicle 4 wheel drive an isolated transfer case is added in addition with a transmission. The transfer case is manually operated and since the system is isolated, it is analyzed separately for having vibrations and noise. In addition, the conventional designs used have manual shifting mechanism for transfer case. A gear type transfer case and a rear cover housing used in the conventional design are shown in Figure 2 and Figure 3 respectively.

Further, the conventional process of proto building is very long and time consuming. Integrated transmission and transfer case has been designed by modifying rear cover (validated through CAE) of conventional transmission to add value to the product.

Therefore, there is a need for a system with integrated speed manual transmission and automatic transfer case to improve noise, power transfer and efficiency performance in addition to robustness.

SUMMARY

According to an embodiment of the present invention, a system having integrated transmission and transfer case, comprises a transmission case (TM), and a transfer case (TC) connected to the transmission case (TM). The transfer case (TC) comprises a lock and unlock mechanism actuated with an electric motor / actuator & formed by a bevel gear, to transmit one of an equal power and differential power to a front axle and a rear axle.

In an embodiment, the transmission case (TM) comprises a main shaft having at least six gear arrangements, at least three synchropacks mounted on the main shaft, and a counter shaft having at least six counter gear arrangements, selectively engaged with the main shaft using at least one gear arrangement.

In another embodiment, the transfer case (TC) comprises a high-speed pair, having a high gear, mounted on a transfer case (TC) drive shaft and a transfer case (TC) driven shaft, the TC drive shaft connected to a main shaft of the transmission case through a coupler, a low speed pair, having a low gear mounted on the TC drive shaft and the TC driven shaft, a final drive pair connected to one of the high-speed pair and the low speed pair using a ring gear, and an electric motor connected to one of the high gear, low gear and neutral position using shifter sleeve, for switching between the high gear and the low gear.

In yet another embodiment, the electric motor is adapted to connect to one of 2 wheel drive and 4 wheel drive through actuation.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1 is a schematic representation of a transmission and transfer case with propeller shafts, according to the prior art illustration.

Figure 2 is a schematic representation of a gear type transfer case, according to the prior art illustration.

Figure 3 is a schematic representation of a rear cover housing, according to the prior art illustration.

Figure 4a is a schematic representation of torque transfer parts in transmission assembly, according to an embodiment of the present invention.

Figure 4b is a schematic representation of a transmission gear train with shifter arrangement, according to an embodiment of the present invention.

Figure 5 is a schematic representation of an integrated transmission and transfer case system to visualize power transmission, according to an embodiment of the present invention.

Figure 6 is a schematic representation of a second high gear, according to an embodiment of the present invention.

Figure 7 is a schematic representation of a third low gear, according to an embodiment of the present invention.

Figure 8 is a schematic representation of a fourth high gear, according to an embodiment of the present invention.

Figure 9 is a schematic representation of a fourth low gear, according to an embodiment of the present invention.

Figure 10 is a schematic representation of torque transfer parts & electrical motor parts in transfer case, according to an embodiment of the present invention.

Figure 11 is a schematic representation of a cross sectional view of integrated transmission and transfer case for vehicle tunnel packaging, according to an embodiment of the present invention.

Figure 12 is a schematic representation of parts engaged in locking or unlocking to transmit unequal power at wheels, according to an embodiment of the present invention.

Figure 13 is a schematic representation of a rear cover housing to adopt integrated design, according to an embodiment of the present invention.

Figure 14 is a schematic representation of an air breather, according to an embodiment of the present invention.

Figure 15 is a schematic representation an aggregate cooling, according to an embodiment of the present invention.

Figure 16 is a schematic representation of a propeller shaft, according to an embodiment of the present invention.

Figure 17 is a schematic representation of a quadrant box modified for better shift feel & force, according to an embodiment of the present invention.

Figure 18 is a schematic representation of a sensor position for capturing noise and vibration, according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE INVENTION

The embodiments of the present invention will now be described in detail. However, the present invention is not limited to the embodiments. The present invention can be modified in various forms. Thus, the embodiments of the present invention are only provided to explain more clearly the present invention to the ordinarily skilled in the art of the present invention.

The specification may refer to “an”, “one” or “some” embodiment(s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations and arrangements of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Figure 4a is a schematic representation of torque transfer parts in transmission assembly, according to an embodiment of the present invention. According to Figure 4a, all gears of main shaft are on bearing i.e. they rotate at different speed with respect to main shaft. All synchropacks that is part no. 15, 16 and 17 as shown in Figure 4b are fixed to the main shaft. Here, the synchropack and the main shaft will rotate at the same speed. Further, all gears that are present on counter shaft are fixed and will be rotating at the same speed.

According to an embodiment of the present invention, the top gear shaft receives power from engine and the power gets transferred to the counter shaft via 4th gear pair. The counter shaft on receiving the power from top gear shaft, it starts rotating. The power from the counter shaft will be transferred to the main shaft but at different speeds based on 6 gears, which are provided on the counter shaft, i.e., 5 speeds and 1 reverse to transfer power at different speeds.

Every gear of main shaft rotates with the mating gear of counter shaft at a particular speed which is defined by gear ratio and number of teeth. Since the main shaft gear is on bearing, it does not rotate the main shaft. The part no. 15, 16 and 17 as shown in Figure 4b are synchropack assembly which move left and right for attaching itself to the gear. When it is attached with gear, the synchropack will rotate at the speed of gear selected. If the synchropack is at the centre then neutral gear is selected. For selecting any gear in particular, synchropack assembly should be moved to either left or right. The transmission case TM includes 3 synchropacks for selecting 6 gears. Suppose if any gear is selected through synchropack, the main shaft will be rotated at the same speed as the gear selected through synchropack and all other gears will be freely rotated.

Figure 5 is a schematic representation of an integrated transmission and transfer case system to visualize power transmission, according to an embodiment of the present invention.

The present invention describes a system with integrated 5 speed manual transmission and automatic transfer case. The system comprises a transmission case (TM), and a transfer case (TC). The transfer case (TC) comprises a lock and unlock mechanism formed by a bevel gear and an electric motor / actuator, to transmit either equal power or differential power to a front axle and a rear axle depends upon the requirement or load condition.

In one embodiment, the transmission case (TM) comprises a main shaft having at least six gear arrangements, at least three synchropacks mounted on the main shaft, and a counter shaft having at least six counter gear arrangements. The counter shaft is adapted to selectively engaged with the main shaft using at least one gear arrangement.

In one embodiment, the transfer case (TC) comprises a high-speed pair, a low-speed pair, a final drive pair and an electric motor. The high-speed pair includes a high gear which is mounted on a transfer case (TC) drive shaft and a transfer case (TC) driven shaft. The TC drive shaft is connected to the main shaft of the transmission case through a coupler.

The low speed pair includes a low gear which is mounted on the TC drive shaft and the TC driven shaft.

The final drive pair is connected to either the high-speed pair or the low speed pair using a ring gear. The electric motor is connected to the high gear and low gear using shifter sleeve, for switching between the high gear and the low gear.

In an embodiment, the high-speed pair includes the high gear mounted on the TC drive shaft through a bearing to get rotated freely at different speeds irrespective of the TC drive shaft. The high-speed pair also includes a first counter gear shaft (CGS1) mounted on the TC driven shaft, is selectively engaged with the high gear.

In an embodiment, the low speed pair includes the low gear mounted on the TC drive shaft through a bearing to get rotated freely at different speeds irrespective of the TC drive shaft. The low speed pair also includes a second counter gear shaft (CGS2) mounted on the TC driven shaft is selectively engaged with the low gear.

In an embodiment, the final drive pair comprises a bevel gear arranged in sun and planet manner, a front axle drive shaft selectively engaged with the bevel gear at one end, a rear axle drive shaft selectively engaged with the bevel gear at another end, a ring gear mounted on the front axle side differential housing being selectively engaged with at least one of the CGS1 and CGS2, and an electric motor engaged with the front axle drive shaft using a differential lock sleeve fork and a shifter sleeve fork.

According to Figure 5, if first gear is selected, the input power from an input shaft is transferred to the counter gear shaft (CGS) through CGS pair which in turn moves the first gear on the main gear (MG) shaft. The power is transferred from transmission (TM) to the transfer case (TC) through sleeve which connects TM and TC. In this embodiment, the power received through the sleeve is passed to output shaft connected to front & rear wheel axle through the high speed pair.

Figure 6 is a schematic representation of a second high gear, according to an embodiment of the present invention. According to Figure 6, if second gear is selected, the input power from an input shaft is transferred to the counter gear shaft (CGS) through CGS pair which in turn moves the second gear on the main gear (MG) shaft. The power is transferred from transmission (TM) to the transfer case (TC) through sleeve which connects TM and TC. In this embodiment, the power received through the sleeve is passed to output shaft connected to front & rear wheel axle through the high speed pair.

Figure 7 is a schematic representation of a third low gear, according to an embodiment of the present invention. According to Figure 7, if third gear is selected, the input power from an input shaft is transferred to the counter gear shaft (CGS) through CGS pair which in turn moves the third gear on the main gear (MG) shaft. The power is transferred from transmission (TM) to the transfer case (TC) through sleeve which connects TM and TC. In this embodiment, the power received through the sleeve is passed to output shaft connected to front & rear wheel axle through the low speed pair.

Figure 8 is a schematic representation of a fourth high gear, according to an embodiment of the present invention. According to Figure 8, if fourth gear is selected, the input power from an input shaft is transferred to the main gear (MG) shaft. The power is transferred from transmission (TM) to the transfer case (TC) through sleeve which connects TM and TC. In this embodiment, the power received through the sleeve is passed to output shaft connected to front & rear wheel axle through the high speed pair.

Figure 9 is a schematic representation of a fourth low gear, according to an embodiment of the present invention. According to Figure 9, if fourth gear is selected, the input power from an input shaft is transferred to the main gear (MG) shaft. The power is transferred from transmission (TM) to the transfer case (TC) through sleeve which connects TM and TC. In this embodiment, the power received through the sleeve is passed to output shaft connected to front & rear wheel axle through the low speed pair.

Figure 10 is a schematic representation of torque transfer parts & electrical motor parts in transfer case, according to an embodiment of the present invention. According to Figure 10, both the high gear and low gear are on bearings i.e. they rotate freely at different speeds irrespective of drive shaft. Once the gear is selected the power is transmitted to counter shaft. If high gear is selected then CGS1 receives power and if low gear is selected then CGS2 receives power. Rotation of counter shaft will be according to the high gear or low gear. After which the power is transmitted to the ring gear. The electric motors are used in locking and unlocking functionalities to provide differential power to front wheel and rear wheel.

Figure 11 is a schematic representation of a cross sectional view of integrated transmission and transfer case for vehicle tunnel packaging, according to an embodiment of the present invention.

Figure 12 is a schematic representation of parts engaged in locking or unlocking to transmit unequal power at wheels, according to an embodiment of the present invention. According to Figure 12, there are 3 shafts in transfer case, 1 for power input (drive shaft) & 2 for power output (Front axle drive shaft and rear axle drive shaft). The shifter sleeve mechanism is fixed to drive shaft i.e. it will rotate at same speed as that of drive shaft. Power will be transferred from transmission to drive shaft of transfer case. The shifter sleeve synchropack is used for selection of high gear or low gear.

According to an embodiment of the present invention, the ring gear is mounted on a coupling and it rotates the coupling. One end of coupling rotates the differential and the differential receives power. At the other end of coupling, the shifter sleeve fork is mounted on coupling i.e. it rotates with coupling. The front axle drive shaft has gear teeth besides the shifter sleeve fork. The state as shown in Figure 12 is unlocked state. When the motor is actuated the shifter sleeve is moved left hand side to slide upon the gear teeth of front axle drive shaft making the system in locked state. Thus, both front and rear drive shafts will be connected and same power will be transferred.

Further, the rear axle drive shaft is rotated from one of the gear of the differential. Differential has the property of transferring same and different power along its both ends. Front axle drive shaft transfers power to front wheels through front axle whereas rear axle drive shaft transfers power to rear wheels.

According to the present invention, a transmission is an aggregate with torque transfer parts such as gears, shafts, hubs, synchronizers, sleeves bearings & structural parts like machined housings as shown in Figure 1. The integrated transmission and transfer case is designed to capture voice of customer (VOC), compact fitment on vehicle, serviceability, cost and then matching the competitive vehicle performance expectation for transmission and transfer case. The transfer case is also an aggregate having similar parts as transmission and it has two gear speeds to transfer the power between high and low, which is actuated using an electric motor. The complete assembly aggregate that is integrated transmission and transfer case is tested as a single unit similar to vehicle usage condition.

Further, a differential mechanism inside the transfer case is used to generate locking and unlocking state by which differential torque is transferred to front and rear wheel axle. This whole design is implemented to transfer power for all-time 4 wheel drive application. Differential has straight bevel gears arranged in sun and planet manner. Both the transmission and transfer case are designed with 75W90 lubricating oil for external temperature conditions. Bearings such as ball bearings and taper roller bearings that are used in transmission and transfer case are designed as per application. There are 6 bearings in transmission and 8 bearings in transfer case.

According to the present invention, the designed torque capacity of this indigenous integrated transmission and transfer case is 185 Nm. The structure is well tested on a multipurpose rig for endurance and fatigue and no part failure was observed even in endurance testing of 752 hours decided on product life and duty cycle expected. The product parts are designed for environmental conditions of -40°C to 50°C.

According to the present invention, the value additive changes that are done are as follows.
Adaptability: Transmission housings such as rear cover and clutch housing were designed in modular concept to suit adaptability as per interface dimensions and vehicle floor plan. Mounting pads are designed and relocated in transfer case for three point mounting as shown in Figure 13.

Compactness & rigidity: For shifting modal frequencies beyond the scope of working range like resonance frequency, the structure is made more rigid than earlier. This in turn results in elimination of structure born noise. Modal frequencies are calculated using Computer-Aided Engineering (CAE) analysis. A stiffer structure is made by ribs modification and addition.

Cost reduction: Material cost reduction is emphasized by reduction in weight and ensuring cost competitiveness in mating part like propeller shaft with less that 2° inclination angle.

Air Breather: The design is very compact and thus air breather is added to the design for proper air release without oil leakage with fins from inside of rear cover as shown in Figure 14.

Aggregate Cooling: External rib structure is provided in new rear cover for cooling purpose as shown in Figure 15. Earlier the structure itself takes care of the cooling.

Oil Capacity: Although the product is re-conceptualized and designed according to the above stated points, adequate oil volume is ensured in new design so that lubrication requirements will be qualified according to lubricating and oil cooling conditions.

Overall length of Transmission: Due to modifications in design the overall length of the transmission reduces which is important design criterion for vehicle fitment and performance in terms of noise & vibration which is the unique selling point (USP) of the product.

Centre distance and output shaft axis are redesigned to improve propeller shaft inclination angle less than 2 degrees as shown in Figure 16, so that overall durability of mating parts of aggregates improves in addition to vibration optimization which increases passenger comfort & driving pleasure. At the same time by improving this, care is taken that transfer case should not be the limiting factor for adequate ground clearance.

Integrated Transmission and transfer case being a single unit is tested together for yielding better performance. Assembly of this integrated transmission and transfer case is modular in nature and is done with all standard tools. Thus this design perfectly fulfills Design for Assembly (DFA) in addition to design of performance and cost. This increases customer satisfaction by improving driving comfort as the vibration levels are reduced considerably.

Since two electric motors are used for actuation of gears of transfer case, it improves ergonomics. The electric motors have feedback and regulating mechanism which give step change improvement in safety and usage. For achieving maximum efficiency gear drive power transmission is developed instead of chain or belt drive. Shifting feel is optimized for better shift feel through quadrant box (Q box) lever angles and indicating the leverage requirement on cable change mechanism as shown in Figure 17.

Further, power transmitting efficiency of chain drive is less than gear drive. For the transmission and transfer case of the present invention, the gear power transmission efficiency is between 97%-99%. Electric shifting of transfer case gears with the help of electric motor with programmable logic eliminates manual effort and improves safety.

According to another embodiment of the present invention, a Continuous Variable transmission (CVT) is added in the transfer case. Design validation would be a critical stage for this solution and will not be a cost optimized solution for mid-size competitive car segments. Similar design could be Reversible Variable transmission/ Infinitely Variable Transmission (RVT/IVT) which also transfers variable power to the vehicle.

Electric shift mechanism for lock and unlock, and also for high and low with driving safety is the unique feature.

Single piece construction is manufactured and tested together with propeller shaft which gives significant performance competitive edge on Noise, Vibration and harshness (NVH). In order to capture NVH, multiple sensors are planted/fixed at predefined places on the integrated transmission and transfer case system as shown in Figure 18.

Gear No. Noise (dB) Conventional TM Noise (dB) Modified ITMTC
1 85.1 74
2 84.4 74
3 84.7 78
4 84 80
5 88.7 78

Reduction in noise level is due to composite result of following changes that are done:
Dynamic balancing of all rotating torque transfer (TT) parts, forging complete machining and gear cutting with controlled root run out is achieved with special design of gear cutting tool in manufacturing. The contact area on gear tooth is improved in addition to contact ratio. The distortion is predicted by control of heat treatment processes and forging heat treatment. Also, profile modification, lead crowning and tip relief are incorporated for smooth rolling of gears and also accounting for tooth bending in load condition.

Special processes have been developed for matching the parts on fix centre distance and further optimizing noise and performance of gears before assembly. Hence, class of gears like DIN 8 perform specified life and specified durability with DIN 6/7 gear at much competitive manufacturing cost.

The present designed is a twin gear in transfer case which offers vehicle equally effective for on road and off road / ice conditions. The Aggregate is designed to compliments other aggregates like engine, axles and fitment on vehicle body (Tunnel). Integrated transmission system utilizes building and developing new validation cycle for physical testing on rig. Part level design is done to optimize the cost through equalizing the durability of critical expensive parts.

The process of validation includes noise testing of integrated transmission and transfer case together which is not done in conventional methods. Sensors are used for capturing noise and vibration of transmission and transfer case which is generally not done for validation. Various plots for velocity and acceleration have been plotted for checking vibration and noise thus satisfying customer for NVH issues. And use of differential with bevel gear in transfer case reduces size as well as cost.

According to the present invention, the design is implemented with total improvement in performance, cost, safety and serviceability. The design is done to compliment the performance and fitment of other aggregates like engine, axles, propeller shafts and vehicle body. The integrated design and testing ensures that transmission and transfer case is fit for usage. The analysis procedure of integrated transmission and transfer case is innovative and this design facilitates power like torque regulation between front and rear axle depending on road / tier condition. Gear rattle noise, gear meshing noise, order analysis for gear mesh frequency has been completed so that shared customer expectations regarding noise levels are fulfilled. Gear drive used in transfer case for getting more speeds and torques is innovative and tunneling changes have been done to suit complimentary parts.

According to the present invention, the present design is going to serve the purpose of all time 4 wheel drive vehicle transmission and transfer case for transferring power from engine to wheels of the vehicle on road and off road. In addition to this the transmission performs smooth and much lower in dB value. Also, the life and durability of the product increases by 20-40%.

Further, a comprehensive test rig where input shaft loading or output shaft loading is designed developed and procured. The product developed is tested on test rig which is validated with durability and fatigue condition.

The present invention is applicable to all types of sport utility vehicle (SUV) and high ground clearance vehicles on road and off highway application. Invention could be extrapolated to small utility vehicle like 0.5 Ton to 2 Ton for load carrying in rough condition as well as highway conditions.

All equivalent relationships to those illustrated in the drawings and described in the application are intended to be encompassed by the present invention. The examples used to illustrate the embodiments of the present invention, in no way limit the applicability of the present invention to them. It is to be noted that those with ordinary skill in the art will appreciate that various modifications and alternatives to the details could be developed in the light of the overall teachings of the disclosure, without departing from the scope of the invention.
,CLAIMS:We claim:
1. A system having integrated transmission and transfer case, comprising:
a transmission case (TM); and
a transfer case (TC) connected to the transmission case (TM),
wherein the transfer case (TC) comprising a lock and unlock mechanism formed by a bevel gear and an electric motor / actuator, to transmit one of an equal power and differential power to a front axle and a rear axle.

2. The system as claimed in claim 1, wherein the transmission case (TM) comprises:
a main shaft having at least six gear arrangements;
at least three synchropacks mounted on the main shaft; and
a counter shaft having at least six counter gear arrangements, selectively engaged with the main shaft using at least one gear arrangement.

3. The system as claimed in claim 1, wherein the transfer case (TC) comprises:
a high-speed pair, having a high gear mounted on a transfer case (TC) drive shaft and a transfer case (TC) driven shaft, the TC drive shaft connected to a main shaft of the transmission case through a coupler;
a low speed pair, having a low gear mounted on the TC drive shaft and the TC driven shaft;
a final drive pair connected to one of the high-speed pair and the low speed pair using a ring gear; and
an electric motor connected to one of the high gear, low gear and neutral position using shifter sleeve, for switching between the high gear and the low gear.

4. The system as claimed in claim 3, wherein the electric motor is adapted to connect to one of 2 wheel drive and 4 wheel drive through actuation.

5. The system as claimed in claim 3, wherein the high-speed pair comprises:
the high gear mounted on the TC drive shaft through a bearing to get rotated freely at different speeds irrespective of the TC drive shaft; and
a first counter gear shaft (CGS1) mounted on the TC driven shaft being selectively engaged with the high gear.

6. The system as claimed in claim 3, wherein the low speed pair comprises:
the low gear mounted on the TC drive shaft through a bearing to get rotated freely at different speeds irrespective of the TC drive shaft; and
a second counter gear shaft (CGS2) mounted on the TC driven shaft being selectively engaged with the low gear.

7. The system as claimed in claim 3, wherein the final drive pair comprises:
a bevel gear arranged in sun and planet manner;
a front axle drive shaft selectively engaged with the bevel gear at one end;
a rear axle drive shaft selectively engaged with the bevel gear at another end;
a ring gear mounted on the front axle side differential housing being selectively engaged with at least one of the CGS1 and CGS2; and
an electric motor engaged with the front axle drive shaft using a differential lock sleeve fork and a shifter sleeve fork.