FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
"Test Set Up And Methodology To Find The Efficiency Of Clutch Activation System"
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. Sujit S Mohire, Mr. Shahaji D Patil
and Vithal S Akhand
AH 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 INVENTION
This invention is related to the clutch actuation system of the vehicle. It is specifically focused on test bench setup to determine the behavior of different aggregates of the clutch actuation system of the vehicle and their effect on overall performance of the clutch actuation system.
BACKGROUND OF INVENTION
Generally the performance of the clutch actuation system of the vehicle is measured on the vehicle itself. But because of the limitation of access to the individual aggregate of the clutch system it becomes difficult to determine the behavior of each aggregate or sub system and its effect on the overall performance of the clutch actuation system. The absence of this information poses difficulty during optimization of behavior of clutch actuation system.
To collect this information of how each sub-system or aggregate behaves, a test bench set is prepared to simulate the clutch actuation system. With this test setup, each aggregate of the clutch system is accessible and now it is possible to measure the operational parameters of each aggregate as well as the overall performance clutch system. Even with the test setup it is possible to simulate different wear conditions of the clutch disc easily and predict the change in the behavior of the system. It is possible to alter a specific aggregate and see its effect on the performance quickly. As all the important operational parameters are maintained as in vehicle, the rig measurements show good co-relation with vehicle performance.
BRIEF DESCRIPTION OF INVENTION
In accordance with present invention, the test setup for efficiency mapping comprises of the mounting stand (1), flywheel adaptor(2), flywheel (3), clutch assembly(4), release yoke with metal strips(6), clutch housing(7), guide plate(8),

drive shaft(9), slave cylinder(10), bundy tube (11), pedal box mounting stand (12),clutch master cylinder (13-a), pedal box (14) , string potentiometer (15), pedal force meter(16) dial gauges(17,18), pressure transducers( 19,20). All the operational parameters are maintained to the drawing specifications to exactly simulate the behavior of clutch actuation system in the vehicle. The pressure transducers, pedal force meter, string potentiometer and dial gauges are used to measure system pressure, pedal force, pedal travel and release lever travel respectively during operation. With these parameters measured on the test setup it is possible to determine the effect of each sub assembly/aggregate on load efficiency and stroke efficiency of the actuation system. The test setup enables to simulate quickly the field failure condition by altering a performance an aggregate under consideration during investigation.
The test setup poses an advantage of quick changeover and measurement time for analysis.
In the test bench the flywheel adaptor (2) plays the role of crank shaft of the engine and maintains the distance between rear face of flywheel (3) and mounting stand (1) as that between flywheel rear face and clutch housing (7) mounting face of the engine block. This is the crucial dimension for clutch system. The tapped mounting holes (18) for the clutch housing (7) are provided along with the dowel pins (23) on the vertical plate of the mounting stand (1) as on the engine block. The position of dowel pins is maintained with respect to the centre of the flywheel adaptor to the drawing specifications of engine block. The guide plate (8) houses the bearing for drive shaft (9). The splines of the drive shaft (9) match to the splines of the clutch disc (4b). The pedal box (14) and clutch master cylinder is mounted on a stand (12). The operational parameter such as release bearing travel, clutch pedal travel, clutch master cylinder push rod stand off, fire wall thickness etc are maintained to the drawing specifications of the clutch system so as to simulate the vehicle condition. The string potentiometer (15), pedal force meter (16), dial gauges (17,18) and pressure transducers( 19,20) are mounted at respective locations as shown in Fig. 1.

Method of preparing the test setup for any clutch actuation system comprises
Preparing a mounting stand to house clutch housing of respective clutch
system
Preparing a flywheel adaptor (2) to maintain the dimension 'dl' in the Fig 3.
and to house the pilot bearing (26) for drive shaft (9).
Preparing a guide plate (8) to house the bearing (28) for drive shaft (9) and to
maintain the alignment of drive shaft with respect to the flywheel (3).
Preparing a drive shaft of correct length with splines (21) to suit the splines
of the clutch disc (4a).
Adaptation of pressure transducers(19,20) on bundy tube (11a) and flexible
hose (11b).
Preparing the mounting stand (12) for pedal box (14) to maintain the
mounting conditions for clutch master cylinder (13a) and pedal box (14).
Selecting the clutch housing, clutch assembly, clutch master and slave
cylinder and pedal box from the corresponding clutch system,
Modifying release yoke (6) of the corresponding clutch system to attach two
metal strips (22); one at slave cylinder push rod end and other at release
bearing end.
Modifying clutch housing to access the metal strips attached to the release
lever.
STATEMENT OF INVENTION
Accordingly, the present invention discloses an apparatus to determine the efficiency of a clutch actuation system of a vehicle comprising: a first mounting stand for mounting a clutch housing on which is mounted a clutch slave cylinder, said clutch housing provided to house at least a clutch assembly, a release yoke on which is attached metal strips, and a release bearing; a flywheel adaptor for spacingly connecting said first mounting stand and a flywheel, such that, the rear face of said

flywheel is maintained at a disstance from said mounting stand; a guide plate mounted on said clutch housing to house a drive shaft bearing and to maintain the alignment of drive shaft with respect to said flywheel; a second mounting stand for mounting clutch pedal box assembly and clutch master cylinder said clutch master cylinder and said clutch slave cylinder being connected to Bundy tube and flexible hose respectively; pressure measuring means mounted at connection between clutch slave cylinder-flexible hose and clutch master cylinder-Bundy tube respectively; a pedal effort measuring means mounted on foot rest of said clutch pedal; a pedal travel measuring means mounted on said second mounting stand and connected to centre of said foot rest of said clutch pedal; and release lever travel measuring means connected to said metal strips attached to said release yoke.
The invention also discloses a method of determining the efficiency of a clutch actuation system of a vehicle with an apparatus as claimed in the preceding claims comprising the steps of: operating and releasing said clutch pedal to simulate real time operation; acquiring clutch pedal effort, pedal travel and pressures through said pressure transducers on the same time domain with a data acquisition system; recording slave cylinder push rod travel and release bearing travel at dial gauges when clutch pedal is pressed completely against the stopper; and calculating and analyzing the efficiency of various aggregates of said clutch actuation system using the various data acquired and recorded.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 shows a block diagram of the test setup in accordance with this invention.
Figure 2 shows flywheel mounting stand.
Figure 3 shows orthographic view of flywheel adaptor.
Figure 4 shows mounting details for flywheel.
Figure 5 shows guide plate.
Figure 6 shows drive shaft.

DETAILED DESCRIPTION OF INVENTION I. Construction of the Test setup
Fig. 1 shows the test setup for the clutch system.
The vertical plate of the mounting stand (1) houses the mounting holes for clutch housing (7) as well as flywheel adaptor (2) as in Fig. 2. It also houses the dowel pins on which the clutch housing is located. The position of the dowel pins (23) for clutch housing are maintained within 0.05 mm with respect to the centre of flywheel adaptor to ensure the alignment of the clutch housing (7) and drive shaft (9) with respect to clutch assembly (4). The mounting holes (25) of flywheel adaptor (2) are positioned centrally on the vertical plate of mounting stand (1). The mounting holes of the clutch housing (24) are positioned with respect to dowel pins within 0.2 mm. The flywheel adaptor (2) has two flanges, one to mount the adaptor on mounting stand (1) and second to mount flywheel (3) onto it. The length of the flywheel adaptor plays a crucial role in the operation of the clutch system. The length of the flywheel adaptor is selected such that it maintains the dimension 'dl' , (distance between the rear face of flywheel and vertical plate of mounting stand) to the distance of flywheel rear face from mounting face for clutch housing on the engine assembly. The mounting flange for flywheel has tapped holes, spigot and dowel pin for flywheel. The flywheel adaptor also houses a pilot bearing (26) for the drive shaft as in Fig (3).
The guide plate (8) houses the bearing for drive shaft as in Fig. 5. The guide plate has through holes corresponding to mounting holes on gear box side of the clutch housing (7). It also houses the dowel pins for alignment of drive shaft with respect to clutch housing.
The drive shaft (9) has splines corresponding to the splines of the clutch disc as in Fig. 6. The length 'l' of the drive shaft is selected from the information fitment

drawing of the clutch assembly. Drive shaft has two bearing areas, one which fits in the pilot bearing in the flywheel adaptor and other for bearing in the guide plate.
The release yoke (6) is selected from the clutch system of the vehicle. It is modified by attaching two metal strips on it, one near release bearing area and second near groove for slave cylinder push rod.
A pressure transducer (19) and pressure transducer (20) is mounted at connection between slave cylinder (10) - flexible hose (1 lb) and master cylinder (13a) - bundy
tube (11a) respectively.
Pedal box mounting stand is used to mount the pedal box assembly onto it. It houses a piece of fire wall of vehicle under consideration. This is to ensure the mounting conditions of the clutch master cylinder (13-a).
II. Preparation test setup: (Fig. 1)
1. Mount the flywheel (3) on flywheel adaptor (2) which in turn shall be mounted on the vertical plate of the mounting stand (1). Mount the clutch assembly (4) on the flywheel(3) and clutch housing(7) along with release bearing(5) and release yoke(6) on the mounting plate.
2. Mount the clutch slave cylinder (10) on the clutch housing (7) with push rod of slave cylinder (10) located in the release yoke (6).
3. Mount the pedal box (14 ) on the pedal box stand (12).
4. Mount the clutch master cylinder (13-a) on the pedal box (14) and make the connection between push rod of master cylinder and clutch pedal.

5. Make the connections of the bundy tube (11-a ) and flexible hose ( 11-b) to Clutch master cylinder (13-a) and Clutch slave Cylinder (10) respectively.
6. Fill the reservoir (13-b) with recommended brake fluid and bleed the actuation system completely.
7. Adjust specified clutch pedal travel with stopper bolt.
8. Measure and ensure the clutch pedal height in released condition is as per drawing specification.
9. Ensure that the clutch is disengaged for the specified clutch pedal travel.
10. Fix the pedal effort meter (16) on the foot rest of the clutch pedal. Fix the free end of the string potentiometer (15) at the centre of the foot rest of the clutch pedal. Mount the string potentiometer on the mounting stand (12) as in Fig. 1. Adjust the floor height and the distance of the string potentiometer from the mounting of the pedal box corresponding to the vehicle reference point as specified in the drawing.
11. Mount one pressure transducer near the output of Clutch master cylinder (13-a) on bundy tube and one pressure transducer near the input of slave cylinder (10) in the hydraulic line.
12. Mount the dial gauges (17,18) on the stands with the probes touching to metal strips welded to release yoke to measure the respective travels.
Now the setup is ready for the measurements.

III. Measurements

1. Place a adjustable (height) chair near the test setup. Adjust the height according to height of the seat in the vehicle.
2. Sit onto the chair to operate the clutch pedal. Press the clutch pedal as in the vehicle with the usual speed. Complete the clutch pedal travel (press the clutch pedal against the stopper and then release the pedal).
3. Acquire the clutch pedal effort, pedal travel and pressures through both the pressure transducers on the same time domain with data acquisition system (Refer Fig. 1).
4. Record the slave cylinder push rod travel and release bearing travel at both the dial gauges, 17 and 18 respectively, when pedal is pressed completely against the clutch pedal stopper.
5. Apart from above measurements, measure the release of the clutch assembly (4) before its fitment in the test setup.
IV. Calculations and analysis
1. Clutch release yoke stroke efficiency:
Yoke Stroke Efficiency =
Actual Yoke Travel
Theoretical Yoke Travel
Theoretical Yoke Travel = Measured clutch release bearing travel × Release Yoke Ratio
2. Hydraulic Efficiency ( Stroke Efficiency):

3. Load Efficiency Pedal Box assembly ( Pedal box + CMC) :
(Force Available at the CMC piston based on the system pressure at CMC)
Pedal box Asse Effi. =
(Theoretical force available at CMC piston based the force applied at foot rest of clutch pedal)

(Note: Consider the pressure corresponding to peak load condition )
Force available at CMC piston = CMC piston area x System Pressure based on system pressure
Theoretical force available at CMC = Pedal effort x Pedal ratio piston based pedal effort
4. Load Efficiency of CSC and Release yoke - Release bearing Assembly:
Load Efficiency of CSC & R. yoke Assem. =
Force transferred to clutch release bearing
Force Availableat the CSC piston based on the system pressure

Force available at CSC piston = CSC piston area x System Pressure @ system pressure

5. System Efficiencies:

5.1 System Stroke Efficiency = Stroke eff of release yoke x Hydraulic Stroke eff.
5.2 System Load Efficiency = Load eff. of pedal box. x Load eff. of CSC and release yoke

WE CLAIM
An apparatus to determine the efficiency of a clutch actuation system of a vehicle comprising:
a first mounting stand for mounting a clutch housing on which is mounted a clutch slave cylinder, said clutch housing provided to house a clutch assembly, a release yoke on which is attached metal strips, and a release bearing;
a flywheel adaptor for spacingly connecting said first mounting stand and a flywheel, such that, the rear face of said flywheel is maintained at a distance from said mounting stand;
a guide plate mounted on said clutch housing to house a drive shaft bearing and to maintain the alignment of drive shaft with respect to said flywheel;
a second mounting stand for mounting clutch pedal box assembly and clutch master cylinder, said clutch master cylinder and said clutch slave cylinder being connected by Bundy tube and flexible hose respectively; pressure measuring means mounted at connection between clutch slave cylinder-flexible hose and clutch master cylinder-Bundy tube respectively; a pedal effort measuring means mounted on foot rest of said clutch pedal;
a pedal travel measuring means mounted on said second mounting stand and connected to centre of said foot rest of said clutch pedal; and release lever travel measuring means connected to said metal strips attached to said release yoke.
The apparatus as claimed in claim 1, wherein said flywheel adaptor comprises of two flanges, one of said flanges being mounted on said mounting plate and the other of said flanges provided for mounting said flywheel onto it.
The apparatus as claimed in claim 1, wherein tapped mounting holes for mounting said clutch housing are provided along with dowel pins on said first

mounting stand.
4. The apparatus as claimed in claim 1, wherein splines of said drive shaft is
provided to match the splines of clutch disc of said clutch assembly.
5. The apparatus as claimed in claim 3, wherein said dowel pins are maintained within 0.05 mm with respect to the centre of said flywheel adaptor.
6. The apparatus as claimed in claim 1, wherein said apparatus comprises a brake fluid reservoir located proximal to said clutch master cylinder.
7. The apparatus as claimed in claim 1, wherein the pressure, pedal effort, pedal travel and release lever travel are measured using pressure transducers, pedal effort meter, string potentiometer and dial gauges respectively.
8. A method of determining the efficiency of a clutch actuation system of a vehicle with an apparatus as claimed in the preceding claims comprising the steps of:
operating and releasing said clutch pedal to simulate real time operation; acquiring clutch pedal effort, pedal travel and pressures through said pressure transducers on the same time domain with a data acquisition system; recording slave cylinder push rod travel and release bearing travel at dial gauges when clutch pedal is pressed completely against the stopper; and calculating and analyzing the efficiency of various aggregates of said clutch actuation system using the various data acquired and recorded.
9. The method as claimed in claim 8, wherein the release load characteristics of
the clutch assembly is measured prior to its fitment in the apparatus.

10. An apparatus to determine the efficiency of a clutch actuation system of a vehicle as hereinabove described with reference to the accompanying drawings.
11. A method of determining the efficiency of a clutch actuation system of a vehicle as hereinabove described with reference to the accompanying drawings.
Dated this 17th day of March 2009
TATA Motors Limited By their Agent & Attorney

(Karuna Goleria) of De PENNING & De PENNING