FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION INTEGRATED ENDURANCE TEST RIG FOR MASTER LIGHT SWITCH
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Mr. Uday Shankar Sambare & Mr. Rajendra Yadaorao Khode
Both are Indian nationals
of TATA MOTORS LIMITED,
An Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The invention generally relates to integrated test rig for Master Light Switch (MLS) controlling head lamp, parking, off, front and rear fog light functions. In particular the invention relates to automated endurance testing of such Master Light Switch by such integrated test rig.
BACKGROUND OF THE INVENTION
Conventionally, head lamps, parking, off, front and rear fog light functions are included in Master Light Switch (MLS). Head Lamp, parking and off functions can be performed by rotary / angular movement of a function selector knob. To operate, front and rear fog light, the function selector knob needs to be actuated linearly and at times with the "Cork Screw" motion.
In conventional scenarios endurance testing for each of the above functions is performed manually i.e. by rotating the function selector knob 30000 times by hand for each function. Front and rear fog function endurance used to be done on separate automated test rig for 20000 cycles.
One limitation observed in the above methods of testing is vehicle mounting condition of the Master Light Switch (MLS) is not taken into consideration while simulating the endurance test.
Further, as the function selector knob is manually operated, operating forces may vary from person to person and time to time. The Master Light Switch (MLS) may not be tested at maximum permissible forces to test the worst condition.
As the conventional method of testing is a manual process, there exists possibility of errors/mistakes in capturing the failures of the Master Light Switch (MLS). Further there is possibility of error in counting of number of endurance cycles. In

addition, skilled manpower is required to perform, monitor and record such test results.
Furthermore, testing time of Master Light Switch (MLS) is high as each function cannot be tested, simultaneously. Further compounding effect of multiple operations cannot be simulated to test complex operating conditions.
Based on the above discussion, there exists a need to provide an integrated test rig capable of simulating vehicle operating condition for testing the Master Light Switch (MLS), which obviates the above mentioned drawbacks.
SUMMARY OF THE INVENTION
The main object of the present invention is to provide an integrated test rig capable of simulating vehicle operating condition for conducting endurance test of a Master Light Switch (MLS) with a "Cork Screw" motion for rear, front fog and parking functions simultaneously.
Another object of the present invention is to provide procedure to validate components for targeted endurance cycles under criterion customer usage and provide the method of failure simulation which enhances the product life.
Another object of the present invention is to provide an integrated test rig capable of simulating vehicle operating condition for conducting endurance test of a Master Light Switch (MLS), which permits testing at maximum specified forces at worst condition.
Another object of the present invention is to provide an integrated test rig capable of simulating vehicle operating condition for conducting endurance test of a Master Light Switch (MLS), which results in simultaneous testing of multiple operations and reduction in testing time.

Another object of the present invention is to provide an integrated test rig capable of simulating vehicle operating condition for conducting endurance test of a Master Light Switch (MLS), which eliminates possibility of counting error.
In order to achieve the above mentioned objects the invention discloses an integrated endurance test rig configured for automated testing of Master Light Switch controlling head lamp, parking and off, front and rear fog functions. The integrated endurance test rig includes a rigid frame for mounting a test rig structure and fixing the test rig to the ground, a clamping fixture for holding the Master Light Switch fixed to it at an inclined angle equal to an actual angle of mounting of the Master Light Switch in a vehicle, at least one driving means for actuating angular and linear motion of a function selector knob of the Master Light Switch, wherein such linear and angular motion of the function selector knob correspond to head lamp, parking and off, and front and rear fog functions, and a control unit for controlling direction and angle of rotation of the at least one driving means for generating angular and linear motion of the function selector knob and synchronizing such angular and linear motion simultaneously to produce "Cork Screw" motion for testing the Master Light Switch.
In an embodiment, the integrated endurance test rig further includes forward and reverse limit switches for regulating the linear movement of the function selector knob. Further, it includes angular step limit switches for regulating the angular movement of the function selector knob.
In an embodiment, the control unit is further configured for counting the number of endurance cycles and the function failures during endurance test.
In an embodiment, the integrated endurance test rig further includes an electric bulb load to simulate a vehicle electrical load. Further it also includes a power supply unit for supplying power to the control unit and the electric bulb load.

In an embodiment, the control unit is a Programmable Logic Controller (PLC), the driving means are DC motors, and the power supply unit is a DC power supply.
It is to be understood that both the foregoing general description and the following detailed description of the present embodiments of the invention are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other features and other advantages of the invention will be better understood and will become more apparent by referring to the exemplary embodiments of the invention, as illustrated in the accompanying drawings, wherein
FIG. 1 schematically illustrates an integrated endurance test rig for testing Master Light Switch (MLS) in vehicle operating condition according to one embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Reference will now be made to the exemplary embodiments of the invention, as illustrated in the accompanying drawings. Where ever possible same numerals will be used to refer to the same or like parts.
The invention discloses an integrated endurance test rig for testing Master Light Switch (MLS) in vehicle operating condition. The Master Light Switch may have control on head lamp, parking and off, front and rear fog functions. FIG. 1

schematically illustrates such an integrated endurance test rig (100) for testing Master Light Switch (MLS) in vehicle operating condition according to one embodiment of the present invention.
According to the present invention, the integrated endurance test rig (100) for vehicle mounted MLS test includes a rigid frame (15) and support frame (3) to mount the structures and fix the same on to the ground. A MLS (2) fixed to a clamping fixture (1) for test purpose. The clamping fixture (1) is inclined at an angle equal to the angle of mounting of the MLS (2) as in the vehicle.
Further the integrated endurance test rig (100) includes driving means such as a DC motor (5) for rotational/ angular movement of the function selector knob of the MLS (2). The output shaft of the DC motor (5) is coupled to a gripper (4). The gripper (4) holds the function selector knob of the MLS (2). Further, 3 angular step limit switches (6a. 6b. and 6c) are employed to restrict the angular rotation of the DC motor (5). The position of the angular step limit switches (6a. 6b. and 6c) are such that they restrict the movement of the DC motor (5) exactly at each detent position of the MLS (2) i.e. off, headlamp and park. The number and displacement of the angular step limit switches (6a. 6b. and 6c) may be adjusted as per switch configuration. In one embodiment, the angular step limit switches (6a. 6b. and 6c) may be mounted on base plate of an angular drive assembly.
The integrated endurance test rig (100) includes another DC motor (7) for facilitating forward and reverse linear movement of the selector knob of the MLS (2). The output shaft of the DC motor (7) is coupled to a drum wheel on which a cable or rope (8) is wounded for linear drive. The cable (8) is fixed to a guide plate (14) on both the sides. Rotation of the DC motor (7) results in winding and unwinding of the cable (8) on the drum wheel and in turn the forward and reverse linear movement of the guide plate (14). Further, the DC motor (5) is also mounted on the guide plate (14). Therefore any forward and reverse linear movement of the guide plate (14) results in forward and reverse movement of the DC motor (5) as

well as in the gripper and finally in the selector knob function. The forward and reverse limits are restricted by two forward and reverse limit switches (10a) and (10b) mounted on a linear drive channel (9), which may be adjusted to get the desired stroke length.
The "Cork Screw" motion may be activated through synchronization of the angular and linear movement. Such synchronized function may be controlled by a control unit such as a PLC (11). The PLC (11) also may control the direction and angle of rotation of both the DC motors (5) and (7). Additionally, the counter feature in the PLC (11) is used for counting the number of function failures and number of endurance cycles for each function separately.
A power supply unit such as a DC power supply unit (16) may supply power to the PLC (11) and an electric bulb load (13) to simulate vehicle electric load. Wiring
(12) may be used for making necessary connections with the MLS (2) and the electric bulb load (13). The electrical load bank (13) is connected as per specification required at each position of the MLS (2). The same electric bulb load
(13) serves the purpose of visual indication of make and break of moving contacts at each position of the MLS (2).
When the power supply unit (16) is switched ON, the PLC (11) monitors the input signals it receives, reads the program in the CPU, processes the data and sends the output signal to both the DC motors (5 and 7). On receiving the power the motors (5 and 7) rotate in the required direction according to the logic programmed in the PLC (11). The angle of rotation of the motors (5 and 7) for each position is limited by angular step limit switches (6a, 6b, 6c, 10a and 10b). The force and torque is set as per the required specifications. Furthermore, the worst testing condition can also be simulated and applied by controlling the input voltage of the motors (5 and 7). The time delay at each detent position Is controlled through the timer in the PLC
(11).

The sequence of operations in one endurance cycle of MLS is explained with the following table. One endurance cycle of MLS comprises selector knob movement as follows:
MLS selector knob rotation and movement

Sr.
No. Selector Knob rotation Movement
1 OFF ► Headlamp Angular
2 In Headlamp position—► Pull Front fog and Rear fog Linear
3 In Headlamp position—► Press Front fog and Rear fog Linear
4 Headlamp ► Park Angular
5 In Park position ► Pull Front fog and Rear fog Linear
6 From Park and Rear fog move knob to Headlamp position Angular and
linear (Cork
Screw
movement)
7 Headlamp ► OFF Angular
Following table summarizes the condition of limit switches at each function of
MLS.
Step-1: Initial / Neutral Position

Limit
switches Name 6a 6b 6c 10a 10b

Status Closed Open Open Closed Open
Functions Name Off Parking Head lamp Front fog Rear fog

Status On Off Off Off Off

Step-2: Forward-Parking position
Limit switches Name 6a 6b 6c 10a 10b

Status Open Closed Open Closed Open
Functions Name Off Parking Head lamp Front fog Rear fog

Status Off On Off Off Off
Step-3: Forward- Fog lamps at Parking Position
Limit switches Name 6a 6b 6c 10a 10b

Status Open Closed Open Open Closed
Functions Name Off Parking Head lamp Front fog Rear fog

Status Off On Off On On
Step-4: Fog lamps at Head lamp Position
Limit switches Name 6a 6b 6c 10a 10b

Status Open Open Closed Open Closed
Functions Name Off Parking Head lamp Front fog Rear fog

Status Off On On On On
Step-5: Head lamp Position
Limit switches Name 6a 6b 6c 10a 10b

Status Open Open Closed Closed Open
Functions Name Off Parking Head lamp Front fog Rear fog

Status Off On On Off Off

Step-6: Reverse- Parking Position
Limit
switches Name 6a 6b 6c 10a 10b

Status Open Closed Open Closed Open
Functions Name Off Parking Head lamp Front fog Rear fog

Status Off On Off Off Off
Step-7: Reverse, Fog lamps at parking Position
Limit switches Name 6a 6b 6c 10a 10b

Status Open Closed Open Open Closed
Functions Name Off Parking Head lamp Front fog Rear fog

Status Off On Off On On
Step-8: Reverse- Neutral Position
Limit
switches Name 6a 6b 6c 10a 10b

Status Closed Open Open Closed Open
Functions Name Off Parking Head lamp Front fog Rear fog

Status On Off Off Off Off
Components Listing:
SR. NO. Description
1 Clamping Fixture
2 Master Light Switch (M LS)
3 Support/Safety Frame for MLS & mountings

4 Knob Gripper/Holder
5 DC Motor for angular operation (Angular Drive)
6a,6b,6c Angular step limit switches
7 DC Motor for linear operation (Linear Drive)
8 Rope of linear drive
9 Guide channel of linear drive
10a, 10b Linear step limit switches
11 Programmable Logic Controller (PLC)
12 MLS to Load Bank Circuitry/Wiring
13 Electrical load bank
14 Guide Plate of linear drive
15 Base Plate with rigid frame
16 DC Power supply unit
100 Integrated Test Rig
The main advantage of the integrated test rig is the endurance test of the Master Light Switch for head lamp, parking, off, rear and front fog function can be done simultaneously as in actual vehicle operating condition.
The automated test rig allows the user to test the Master Light switch at maximum specified forces which represents the worst condition.
Further optimization of skilled man power and reduction in man hours may be achieved. The testing time may come down by 20% as all functions can be tested simultaneously. It also results in reduction of development time of components.

Use of inbuilt counter feature of the PLC for counting the endurance cycle for each function separately may eliminate the possibility of counting errors. Further it may also result in saving of manpower.
The test may provide quick, fairly accurate results and require no special testing skill and high investments. This effectively may Iead to reduction of overhead cost of testing.
Further the test rig may be used for wide range of vehicles having different performance level with minor changes.
The use of the PLC enables to program the time within which the selector knob has to be moved from one position to the other and the time of which the knob is to be held in one position accurately.
Furthermore, the test rig may have safety feature such as on selection of "failure detect" mode the rig stops automatically when function failure occurs due to the interlock provided in rig.
It is to be understood by a person of ordinary skill in the art that various modifications and variations may be made without departing from the scope and spirit of the present invention. Therefore, it is intended that the present invention covers such modifications and variations provided they come within the ambit of the appended claims and their equivalents.

WE CLAIM
1. An integrated endurance test rig configured for automated testing of Master Light Switch controlling head lamp, parking and off, front and rear fog functions comprising:
a rigid frame for mounting a test rig structure and fixing the test rig to the ground;
a clamping fixture for holding the Master Light Switch fixed thereto at an inclined angle equal to an actual angle of mounting of the Master Light Switch in a vehicle;
at least one driving means for actuating angular and linear motion of a function selector knob of the Master Light Switch, wherein such linear and angular motion of the function selector knob correspond to head lamp, parking and off, and front and rear fog functions; and
a control unit for controlling direction and angle of rotation of the at least one driving means for generating angular and linear motion of the function selector knob and synchronizing such angular and linear motion simultaneously to produce "Cork Screw" motion for testing the Master Light Switch.
2. The integrated endurance test rig for Master Light Switch according to claim 1 further includes forward and reverse limit switches for regulating the linear movement of the function selector knob.
3. The integrated endurance test rig for Master Light Switch according to claim 1 further includes angular step limit switches for regulating the angular movement of the function selector knob.
4. The integrated endurance test rig for Master Light Switch according to claim 1, wherein the control unit is further configured for counting the number of endurance cycles and the function failures during endurance test.

5. The integrated endurance test rig for Master Light Switch according to claim 1 further comprising an electric bulb load to simulate a vehicle electrical load.
6. The integrated endurance test rig for Master Light Switch according to claim 5 further comprising a power supply unit for supplying power to the control unit and the electric bulb load.
7. The integrated endurance test rig for Master Light Switch according to claim 1, wherein the control unit comprises a Programmable Logic Controller (PLC).
8. The integrated endurance test rig for Master Light Switch according to claim 1, wherein the at least one driving means comprises at least one DC motors.
9. The integrated endurance test rig for Master Light Switch according to claim 6, wherein the power supply unit comprises a DC power supply.