TRANSIENT CLUTCH LUBRICATION CONTROL SYSTEM
FIELD OF INVENTION
The present invention relates to a lubrication system for clutch. More particularly, the present invention relates to a transient clutch override lubrication control system, which provides transient supply of additional cooling medium during such excess slip or clutch override. Further, the present invention relates to a transient clutch override lubrication control system, which provides variable rate of oil flow to a clutch friction discs based on the different energy demands.
BACKGROUND OF INVENTION
Generally, wet clutches for vehicles or power take-off shafts, such as are applied, for example, in agricultural and industrial vehicles, usually contain a hydraulically actuated piston which compresses a stack of clutch disks or plates. The clutch is engaged by friction locking, which generates heat. To avoid excessive wear, the clutch is cooled by a cooling fluid, for example, cooling oil, to transfer heat away from the clutch. Such cooling of the clutch is primarily required during the slippage phase, when the clutch linings are heated by the slip friction, that is, when the torque transmitted by the clutch is less than the torque delivered by the engine. For example, the maximum input torque may be 65% of the rated torque of the clutch, depending upon the design of the clutch. As a first approximation, the torque transmitted by the clutch is proportional to the hydraulic piston pressure, hence slippage of the clutch will occur when the piston pressure is lower than approximately 65% of the hydraulic system pressure.
In mechanically actuated wet clutch systems, cooled and filtered hydraulic oil is flowed through the clutch assembly. The cooling oil is flowed through these clutches continuously as long as they are engaged. However, energy is wasted when cooling oil flow is continued beyond the time when the excess heat has been removed from the clutch. Also, in conventional

mechanically actuated clutch systems, the driver controls the clutch slip, this leads to excessive heat generation, clutch wear and premature failures.
In conventional mechanically operated wet clutch systems, clutch engagement modulation and clutch slip are not controlled. This fully depends on operators driving skill. This may lead to excess clutch override and excess clutch slip. Wet clutch friction plates are highly sensitive with slip time, temperature and slip speed. One of the major challenge in the conventional mechanical actuated wet clutch design is to balance the cooling oil flow. This is vital and complicated to improve the energy capacity, heat dissipation and control friction surface temperature during clutch slip and engaging conditions.
US Patent document 2833385 discloses a hydraulically operated clutch system for coupling a driving shaft to the driven shaft, said hydraulically operated clutch system comprising means for supplying cooling fluid to the clutch including a second valve, a first hydraulic motor for operating the first valve to engage and disengage the clutch and for opening the second valve to supply cooling fluid to the clutch while it is being engaged, and means for momentarily reopening the second valve to supply cooling fluid to the clutch while it is being disengaged including a second hydraulic motor.
CA Patent document 1231310 relates to a hydraulic control circuit that controls flow of cooling oil to a wet clutch. The hydraulic control circuit normally maintains a reduced or zero flow, but temporarily increases flow of cooling oil when the clutch changes from a disengaged to an engaged state.
US Patent document 5224578 discusses about clutch coolant flow control in which a coolant control valve is controlled in such a way that it interrupts the coolant flow to the clutch during operation with clutch engaged or disengaged and opens the coolant flow to the clutch during the engagement process of the clutch and, if required, for a predetermined time interval following the engagement process.

All of the above cited prior-art deals with clutch lubrication control system. But none of the technology proposes a transient clutch override lubrication control system, which provides variable rate of fluid flow to a clutch friction discs based on the different energy demands. Accordingly, there exists a need for a transient clutch override lubrication control system, which provides transient cooling fluid flow to a clutch friction discs based on rate of engagement and slip speed difference. Further, there exist a need for a transient clutch override lubrication control system, which prevents premature clutch failure and increases clutch life to multiple folds.
OBJECTS OF INVENTION
One or more problems of the conventional prior art may be overcome by various embodiment of the present invention.
It is the primary object of the present invention to provide a transient clutch override lubrication control system, which provides increased clutch cooling capacity in severe load cycles and enhances clutch life.
Another objective of the present invention is to provide a transient clutch override lubrication control system, which provides transient supply of additional cooling medium during such excess slip or clutch override.
Yet another object of the present invention is to provide a transient clutch override lubrication control system, which prevents premature clutch failure and increases clutch life to multiple folds.
It is the another object of the present invention to provide a transient clutch override lubrication control system, which provides variable rate of fluid flow to a clutch friction discs based on the different energy demands.

It is the another object of the present invention to provide a transient clutch override lubrication control system, which provides transient cooling fluid flow to a clutch friction discs based on rate of engagement and slip speed difference.
Another objective of the present invention is to provide a single transient clutch override lubrication control system, which controls fluid flow for both main transmission clutch pack and Power Take Off (PTO) clutch pack.
Yet another object of the present invention is to provide a transient clutch override lubrication control system, which delivers increased fluid flow rate during high energy cycles, and reduces the fluid flow rate at clutch lockup cycle and even reduce up to zero fluid flow rate during clutch opened condition.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the invention there is provided a transient clutch override lubrication control system, comprising of:
a first sensor [2] positioned in a pedal cross shaft [1], which actuates a clutch assembly [10], wherein the first sensor [2] measures the linear movement of a clutch release bearing [1a] and pedal angle [A0, A1, A2];
at least two second sensors [3a, 3b] positioned in input shaft and output shaft of the clutch assembly [10] respectively for detecting speed;
at least two pumps [6a, 6b] driven by engine shaft for supplying fluid from a reservoir [12] to lubricate and cool the clutch assembly [10] through a clutch input manifold [9];
at least two control valves [5a, 5b] connected in between respective pumps [6a, 6b] and the clutch assembly [10], and

a controller [4] controls the control valves [5a, 5b] based on the output from the first sensor [2] and the second sensors [3a, 3b], thereby provides variable fluid flow rate to cool the clutch assembly [10] based on energy demand.
It is another aspect of the present invention, wherein the input shaft of the clutch assembly [10] is connected to engine side of vehicle and output shaft of the clutch assembly [10] is connected to transmission side of the vehicle.
It is another aspect of the present invention, wherein a primary pump [6a] and secondary pump [6b] are connected in tandem for supplying fluid from a reservoir [12] to lubricate and cool the clutch assembly [10].
It is another aspect of the present invention, wherein the clutch assembly [10] includes main transmission clutch assembly and Power Take Off (PTO) clutch assembly positioned inside a driveline system.
It is another aspect of the present invention, wherein a pressure switch [7] connected in between the pressure relief valve [8] and clutch input manifold [9] monitors definite fluid pressure controlled by said pressure relief valve [8] in hydraulic circuit at normal and transient condition.
It is another aspect of the present invention, wherein output from the pressure switch [7] is fed to a instrument panel [11] of vehicle to alert the driver through a warning lamp [11b] for fluid pressure.
It is another aspect of the present invention, wherein the first sensor [2] is a position sensor.
It is another aspect of the present invention, wherein the second sensor [3a, 3b] is a speed sensor.
It is another aspect of the present invention, wherein the pump [6a, 6b] is a gear pump.

It is another aspect of the present invention, wherein the control valve [5a, 5b] is a three way two position electro hydraulic solenoid valve.
It is another aspect of the present invention, wherein the fluid is a lubricant oil.
It is another aspect of the present invention, wherein the clutch assembly [10] is a multi-disk mechanically actuated wet type clutch assembly.
Another aspect of the invention there is provided a method for transient clutch override lubrication control, comprising steps of:
measuring the linear movement of a clutch release bearing [1a] and clutch pedal angle [A0, A1, A2] using a first sensor [2] when user actuates a pedal;
i estimating the speed difference between input shaft and output shaft of a clutch
assembly [10] based on output from second sensors [3a, 3b] by a controller [4]; and
controlling control valves [5a, 5b] based on measured linear movement of the clutch release bearing [1a] and clutch pedal angle [A0, A1, A2] and estimated speed difference using the controller [4], thereby provides variable fluid flow rate to cool the clutch assembly [10] based on energy demand.
It is another aspect of the present invention, wherein the controller [4] compares the output from the first sensor [2] and speed difference from the second sensors [3a, 3b] with pre-defined value and actuates the respective control valves [5a, 5b] accordingly.
It is another aspect of the present invention, wherein during continuous loading and high i energy dissipation from the clutch assembly [10], the controller [4] actuates the control valve [5b] along with the control valve [5a] to provide additional fluid flow to the clutch assembly [10] through a clutch input manifold [9] for cooling during transient engagement [E1] condition or excess slip or clutch override.

It is another aspect of the present invention, wherein the controller [4] based on the output from the first sensor [2] and second sensors [3a, 3b], provides output signal to a instrument panel [11] of vehicle to alert the driver through a warning lamp [11a] for clutch transient engagement [E1] condition or excess slip or clutch override.
It is another aspect of the present invention, wherein the transient engagement [E1] condition or excess slip or clutch override occurs during clutch is in fully engaged state.
It is another aspect of the present invention, wherein the controller [4] actuates the control valve [5a] alone to cool the clutch assembly [10] through a clutch input manifold [9] during clutch lockup or partially disengaged [E0] condition.
It is another aspect of the present invention, wherein the controller [4] deactivates fluid supply from a primary pump [6a] supplied to the clutch assembly [10] through the control valve [5a], when clutch is in fully disengaged or open [E2] condition.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 illustrates the transient clutch override lubrication control system according to the present invention.
Figure 2 illustrates the enlarged view of clutch assembly as shown in Figure 1 according to the present invention.
Figure 3 illustrates the oil flow path inside the driveline system according to the present invention.
Figure 4 illustrates the hydraulic circuit diagram of oil flow path in the transient clutch override lubrication control system according to the present invention.
Figure 5 illustrates the block diagram of the transient clutch override lubrication controller according to the present invention.

DETAILED DESCRIPTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
The present invention as embodied by an "Transient clutch override lubrication system" succinctly fulfils the above-mentioned need(s) in the art. The present invention has objective(s) arising as a result of the above-mentioned need(s), said objective(s) being enumerated below. In as much as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation(s)/modification(s) applied to the structural alternative(s)/functional alternative(s) within its scope and purview. The present invention may be embodied in other specific form(s) without departing from the spirit or essential attributes thereof.
Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.
The present invention is thus directed to a transient clutch override lubrication control system, which provides transient supply of additional cooling medium during such excess slip or clutch override. Further, the present invention relates to a transient clutch override lubrication control system, which provides variable rate of oil flow to a clutch friction discs based on the different energy demands.
Referring to Figures 1 to 4, in an embodiment of the present invention, the transient clutch override lubrication control system, comprising of: a first sensor [2] positioned in a pedal cross shaft [1], which actuates a clutch assembly [10], wherein the first sensor [2] measures the linear movement of a clutch release bearing [1a] and pedal angle [A0, A1, A2]; at least two

second sensors [3a, 3b] as shown in Figure 4 positioned in input shaft and output shaft of a clutch assembly [10] respectively for detecting speed; at least two pumps [6a, 6b], wherein a primary pump [6a] and secondary pump [6b] are connected in tandem driven by shaft of a engine [13] as shown in Figure 3 for supplying fluid from a reservoir [12] to lubricate and cool a clutch assembly [10]; at least two control valves [5a, 5b] connected in between respective pumps [6a, 6b] and the clutch assembly [10]; and a controller [4] controls the control valves [5a, 5b] based on the output from the first sensor [2] and the second sensors [3a, 3b], thereby provides variable fluid flow rate to cool the clutch assembly [10] based on energy demand. The input shaft of the clutch assembly [10] is connected to engine side of vehicle and output shaft of the clutch assembly [10] is connected to transmission side of the vehicle.The clutch assembly [10] includes main transmission clutch assembly and Power Take Off (PTO) clutch assembly positioned inside a driveline system.
In the preferred embodiment of the present invention, a pressure switch [7] connected in between the pressure relief valve [8] as shown in Figure 1 and clutch input manifold [9] monitors definite fluid pressure controlled by said pressure relief valve [8] in the hydraulic circuit at normal and transient conditions, output from said pressure switch [7] is fed to a instrument panel [11] of vehicle to alert the driver through a warning lamp [11b] for oil pressure.
In the preferred embodiment of the present invention, the first sensor [2] is a position sensor.
In the preferred embodiment of the present invention, the second sensor [3a, 3b] is a speed sensor.
In the preferred embodiment of the present invention, the pump [6a, 6b] is a gear pump.
In the preferred embodiment of the present invention, the control valve [5a, 5b] is a three way two position electro hydraulic solenoid valve.
In the preferred embodiment of the present invention, the fluid is a lubricant oil.

In the preferred embodiment of the present invention, the clutch assembly [10] is a multi-disk mechanically actuated wet type clutch assembly.
Referring to Figures 1 to 4, in another embodiment of the present invention, the method for transient clutch override lubrication control, comprising steps of:
measuring the linear movement of a clutch release bearing [1a] and clutch pedal angle [A0, A1, A2] using a first sensor [2] when user actuates clutch assembly [10];
estimating the speed difference between input shaft and output shaft of a clutch assembly [10] based on output from second sensors [3a, 3b] by a controller [4]; and
i controlling control valves [5a, 5b] based on measured linear movement of the
clutch release bearing [1a] and clutch pedal angle [A0, A1, A2] and estimated speed difference using the controller [4], thereby provides variable fluid flow rate to cool the clutch assembly [10] based on energy demand.
The controller [4] compares the output from the first sensor [2] and speed difference from the second sensors [3a, 3b] with pre-defined value and actuates the respective control valves [5a, 5b] accordingly. During continuous loading and high energy dissipation from the clutch assembly [10], the controller [4] actuates the control valve [5b] along with the control valve [5a] to provide additional fluid flow to the clutch assembly [10] through a clutch input manifold [9] for cooling during transient engagement [E1] condition or excess slip or clutch override as shown i in Figure 2. The transient engagement [E1] condition or excess slip or clutch override occurs during clutch is in fully engaged state. The controller [4] actuates the control valve [5a] alone to cool the clutch assembly [10] through a clutch input manifold [9] during clutch lockup [E0] condition as shown in Figure 2. The controller [4] deactivates fluid supply from a primary pump [6a] supplied to the clutch assembly [10] through the control valve [5a], when clutch is in fully disengaged or open [E2] condition.

In the preferred embodiment of the present invention, the controller [4] based on the output from the first sensor [2] and second sensors [3a, 3b] provides output signal to the instrument panel [11] as shown in Figure 1 of vehicle to alert the driver through a warning lamp [11a] for clutch transient engagement [EO] condition or excess slip or clutch override.
EXAMPLE
Referring to Figures 1 to 4, the transient clutch override lubrication control system according to the present invention, comprising of: a first sensor [2] positioned in the pedal cross shaft [1] for mapping the linear movement of a clutch release bearing [1a] and clutch pedal angle [AO, A1, A2]; at least two second sensors [3a, 3b] as shown in Figure 4 for estimating the speed difference between input shaft and output shaft of a clutch assembly [10] respectively; at least two pumps [6a, 6b], wherein a primary pump [6a] and secondary pump [6b] are connected in tandem with shaft of a engine [13] as shown in Figure 3 for supplying oil from the reservoir [12] to lubricate and cool the clutch assembly [10]; at least two control valves [5a, 5b] connected in between respective pumps [6a, 6b] and the clutch assembly [10]; and a controller [4] controls the control valves [5a, 5b] based on the output from the first sensor [2] and second sensors [3a, 3b].
The linear movement of the clutch release bearing [1a] and clutch pedal angle [AO, A1, A2] is mapped using the position sensor [2] when user actuates the clutch pedal. The speed difference between the input shaft and output shaft of the clutch assembly [10] is estimated based on output from the second sensors [3a, 3b] by the controller [4]. The controller [4] compares the output from the first sensor [2] and speed difference from the second sensors [3a, 3b] with pre-defined value and actuates the respective control valves [5a, 5b] accordingly, thereby cooling the clutch assembly [10] based on energy demand.
The controller [4] based on the output from the first sensor [2] and second sensors [3a, 3b] provides output signal to a instrument panel [11] as shown in Figure 1 of vehicle to alert the driver through a warning lamp [11a] for clutch transient engagement or fully engaged [E0]

condition or excess slip or clutch override as shown in Figure 2. A pressure switch [7] connected in between the pressure relief valve [8] as shown in Figure 1 and clutch input manifold [9] monitors definite oil pressure controlled by said pressure relief valve [8] in a hydraulic circuit at normal and transient conditions, output from said pressure switch [7] is fed to the instrument panel [11] of vehicle to alert the driver through a warning lamp [11b] for oil pressure.
High energy cycle
During continuous loading and high energy dissipation from the clutch assembly [10], the controller [4] actuates the control valve [5b] along with the control valve [5a] to provide additional fluid flow to the clutch assembly [10] through a clutch input manifold [9] for cooling during transient engagement [E1] condition or excess slip or clutch override as shown in Figure 2. The secondary pump [6b] compensates additional flow required during transient engagement or fully engaged [E1] condition as shown in Figure 2 in addition to the primary pump [6a]. Thus, the transient clutch override lubrication control system provides transient supply of additional cooling medium during such transient engagement [E1] condition or excess slip or clutch override and enhances clutch life.
Lockup cycle
When clutch is in lockup or partially disengaged [E0] condition as shown in Figure 2, the secondary pump [6b] stops supplying additional oil flow required in addition to supply of oil from the primary pump [6a]. The fluid flow from the primary pump [6a] is controlled by the controller [4] through the control valve [5a] and supplied to the clutch assembly [10] through the clutch input manifold [9]. The control valve [5a] alone provides fluid flow to the clutch assembly [10] for cooling during lockup or partially disengaged [E0] condition of the clutch.
Clutch opened condition

When clutch is in fully disengaged or open [E2] condition as shown in Figure 2, the controller [4] deactivates fluid supply from the primary pump [6a] supplied to the clutch assembly [10] through the control valve [5a].
Thus, the transient clutch override lubrication control system, delivers increased flow rate during high energy cycles or clutch transient engagement or fully engaged [E1] condition or excess slip or clutch override condition, reduces the flow rate at clutch lockup [E0] condition and even reduce up to zero oil flow rate during clutch fully disengaged or open [E2] condition. Thus, the transient clutch override lubrication control system, provides variable rate of oil flow to the clutch assembly [10] based on the different energy demands and prevents premature clutch failure and increases clutch life to multiple folds. The transient clutch override lubrication control system provides protracted clutch life, increases the clutch energy capacity and reduce the clutch drag loss.
It will be apparent to the person skilled in the art that the above description is for illustrative purposes only should not be considered as limiting. Various modifications, additions, alterations, and improvements without deviating from the scope of the invention may be made by a person skilled in the art.

WE CLAIM:
1. A transient clutch override lubrication control system, comprising of:
a first sensor [2] positioned in a pedal cross shaft [1], which actuates a clutch assembly [10], wherein the first sensor [2] measures the linear movement of a clutch release bearing [1a] and pedal angle [A0, A1, A2];
at least two second sensors [3a, 3b] positioned in input shaft and output shaft of the clutch assembly [10] respectively for detecting speed;
at least two pumps [6a, 6b] driven by shaft of a engine [13] for supplying fluid from a reservoir [12] to lubricate and cool the clutch assembly [10] through a clutch input manifold [9];
at least two control valves [5a, 5b] connected in between respective pumps [6a, 6b] and the clutch assembly [10], and
a controller [4] controls the control valves [5a, 5b] based on the output from the first sensor [2] and the second sensors [3a, 3b], thereby provides variable fluid flow rate to cool the clutch assembly [10] based on energy demand,
2. The system as claimed in claim 1, wherein the input shaft of the clutch assembly [10] is connected to engine side of vehicle and output shaft of the clutch assembly [10] is connected to transmission side of the vehicle.
3. The system as claimed in claim 1, wherein a primary pump [6a] and secondary pump [6b] are connected in tandem for supplying fluid from a reservoir [12] to lubricate and cool the clutch assembly [10].

4. The system as claimed in claim 1, wherein the clutch assembly [10] includes main transmission clutch assembly and Power Take Off (PTO) clutch assembly positioned inside a driveline system.
5. The system as claimed in claim 1, wherein a pressure switch [7] connected in between the pressure relief valve [8] and clutch input manifold [9] monitors definite fluid pressure controlled by said pressure relief valve [8] in hydraulic circuit at normal and transient condition.
6. The system as claimed in claim 5, wherein output from the pressure switch [7] is fed to a instrument panel [11] of vehicle to alert the driver through a warning lamp [11b] for fluid pressure.
7. The system as claimed in claim 1, wherein the first sensor [2] is a position sensor.
8. The system as claimed in claim 1, wherein the second sensor [3a, 3b] is a speed sensor.
9. The system as claimed in claim 1, wherein the pump [6a, 6b] is a gear pump.
10. The system as claimed in claim 1, wherein the control valve [5a, 5b] is a three way two position electro hydraulic solenoid valve.
11. The system as claimed in claim 1, wherein the fluid is a lubricant oil.
12. The system as claimed in claim 1, wherein the clutch assembly [10] is a multi-disk mechanically actuated wet type clutch assembly.
13. A method for transient clutch override lubrication control, comprising steps of:

measuring the linear movement of a clutch release bearing [1a] and clutch pedal angle [AO, A1, A2] using a first sensor [2] when user actuates clutch assembly [10];
estimating the speed difference between input shaft and output shaft of a clutch assembly [10] based on output from second sensors [3a, 3b] by a controller [4]; and
controlling control valves [5a, 5b] based on measured linear movement of the clutch release bearing [1a] and clutch pedal angle [AO, A1, A2] and estimated speed difference using the controller [4], thereby provides variable fluid flow rate to cool the clutch assembly [10] based on energy demand.
14. The method as claimed in claim 13, wherein the controller [4] compares the output from the first sensor [2] and speed difference from the second sensors [3a, 3b] with pre-defined value and actuates the respective control valves [5a, 5b] accordingly.
15. The method as claimed in claim 13, wherein during continuous loading and high energy dissipation from the clutch assembly [10], the controller [4] actuates the control valve [5b] along with the control valve [5a] to provide additional fluid flow to the clutch assembly [10] through the clutch input manifold [9] for cooling during transient engagement [E1] condition or excess slip or clutch override.
16. The method as claimed in claim 13, wherein the controller [4] based on the output from the first sensor [2] and second sensors [3a, 3b], provides output signal to a instrument panel [11] of vehicle to alert the driver through a warning lamp [11a] for clutch transient engagement [E1] condition or excess slip or clutch override.

17. The method as claimed in claim 15, wherein the transient engagement [E1] condition or excess slip or clutch override occurs during clutch is in fully engaged state.
18. The method as claimed in claim 12, wherein the controller [4] actuates the control valve [5a] alone to cool the clutch assembly [10] through a clutch input manifold [9] during clutch lockup [E0] condition.
19. The method as claimed in claim 12, wherein the controller [4] deactivates fluid supply from a primary pump [6a] supplied to the clutch assembly [10] through the control valve [5a], when clutch is in fully disengaged or open [E2] condition.