FORM 2
THE PATENT ACT 1970
[39 OF 1970]
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See Section 10 and Rule 13]
TITLE: “A VACUUM ASSISTED HYDRAULIC CLUTCH ACTUATION
SYSTEM”
Name and address of the Applicant:
TATA MOTORS LIMITED, an Indian company having its registered office at
Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra,
INDIA.
Nationality: INDIAN
The following specification particularly describes the invention and the manner in which it is to be performed.

TECHNICAL FIELD
The present disclosure relates to a clutch actuation system of a vehicle. More particularly, the present disclosure relates to a vacuum assisted hydraulic clutch actuation system of the vehicle.
BACKGROUND OF DISCLOSURE
In motor vehicle industry standard or manual and automatic shift transmissions are in use. The standard or manual transmissions are very common on light commercial truck and buses, light cars which incur low cost, low weight and low maintenance in comparison with automatic transmissions. A hand operated gear shift lever is provided in a typical standard or manual transmission to change the gear ratio as per requirement.
Presently, there are various types of devices and systems are available for actuating a clutch assembly of the manual transmission motor vehicle. A clutch is used to disengage the transmission from engine during gear selection. The disengagement of clutch is done by the driver by pressing a clutch pedal. The clutch pedal is linked to the clutch fork in the manual transmission by mechanical linkage which allows the driver to use his foot to engage and disengage the clutch assembly. But, the standard transmissions used on light trucks entail excessive clutch pedal effort which results in driver discomfort.
Conventionally, in a clutch actuation system, a pressurized air is used on heavy duty trucks to drive a piston/cylinder arrangement, at an engine side, which is connected to the clutch linkage to provide a boost to the driver's leg pressure to disengage the clutch reducing the clutch pedal effort. The cylinder at the engine side receives air from and discharges air through a control valve which is connected to the clutch linkage. The control valve operation is controlled by the clutch linkage. However, the control valve used conventionally is only for the clutch actuation system. The control valve through which air is drawn is not used for the brake actuation system at the same time. Thus, a separate valve is used to supply air to the brake actuation system.

Further, conventional system uses separate vacuum pumps for both clutch actuation system and brake actuation system which results in extra costs and, complexity and components in the vehicle.
Thus, there is a need for providing vacuum assisted hydraulic clutch actuation system with a vacuum pump for supplying vacuum to both clutch actuation system and brake actuation system for reducing the clutch pedal and brake pedal effort and which is economical.
SUMMARY OF THE DISCLOSURE
The shortcomings of the prior art are overcome and additional advantages are provided through the present disclosure.
Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
The present disclosure provides a vacuum assisted hydraulic clutch actuation system. The system comprises a clutch pedal, a servo booster, a vacuum assist port, a clutch vacuum tank, a vacuum pump, a master cylinder and a slave cylinder. The clutch pedal is mounted on a mounting bracket inside a vehicle cabin of a vehicle. The servo booster is mounted onto the mounting bracket between the clutch pedal and the master cylinder. The servo booster comprises an inlet vacuum channel through which vacuum is supplied to the servo booster. The vacuum in the servo booster is created by the vacuum assist port provided in the servo booster when the clutch pedal is actuated. The clutch vacuum tank is fluidically connected to the servo booster for supplying vacuum from the clutch vacuum tank to the servo booster through the inlet vacuum channel. The vacuum pump is electrically connected to the servo booster for pumping vacuum from the clutch vacuum tank to the servo booster when the clutch pedal is actuated. The vacuum pump is a common to the clutch actuation system and a brake actuation system of the vehicle, which is fluidically connected to the clutch vacuum tank through a first non-return valve and a brake vacuum tank of a brake actuation system through a second non-return valve.

The master cylinder further comprises an inlet hydraulic port through which hydraulic fluid is supplied from a hydraulic fluid tank to the master cylinder. When the clutch pedal is actuated, a hydraulic pressure is created in the master cylinder by means of vacuum pumped from the clutch vacuum tank by the vacuum pump which makes the master cylinder supplies hydraulic fluid to a slave cylinder provided at an engine side of the vehicle for assisting clutch actuation. The slave cylinder is attached to a clutch fork through a clutch linkage fixed on a transmission of the vehicle.
In an embodiment of the present disclosure, actuation of the clutch pedal opens the first non-return valve and actuation of the brake pedal opens the second non-return valve.
In an embodiment of the present disclosure, the servo booster of the system is fluidically connected to a brake pedal. Upon actuating the brake pedal, the second non-return valve gets opened through which the vacuum from the brake vacuum tank is pumped to the servo booster pumped by the vacuum pump. Then, the vacuum from the brake vacuum tank is in turn supplied to the brake actuation system through a flow line valve. The brake actuation system is fluidically connected to the master cylinder to get supply of hydraulic fluid.
The present disclosure provides a method of assisting a vacuum assisted hydraulic clutch actuation system. The method comprises steps of generating a hydraulic pressure in a master cylinder by means of vacuum pumped from a clutch vacuum tank to a servo booster through an inlet vacuum channel. The clutch vacuum tank is fluidically connected to the servo booster for supplying vacuum to the servo booster pumped by a vacuum pump. The vacuum pump is a common to the clutch actuation system and brake actuation system of a vehicle which is fluidically connected to the clutch vacuum tank through a first non-return valve and a brake vacuum tank through a second non-return valve. The vacuum in the servo booster is created by a vacuum assist port provided in the servo booster when a clutch pedal is actuated. Next, the hydraulic fluid from the master cylinder is supplied to a slave cylinder provided at an engine side of the vehicle for assisting clutch actuation.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects and features described above, further aspects, and features will become apparent by reference to the drawings and the following detailed description.
OBJECTIVES OF THE PRESENT DISCLOSURE
An object of the present disclosure is to provide a vacuum assisted hydraulic clutch actuation system for actuating the clutch actuation system with the help of vacuum.
One object of the present disclosure is to provide the vacuum assisted hydraulic clutch actuation system which has a common vacuum pump which supplies vacuum to the clutch actuation system and to a brake actuation system.
One object of the present disclosure is to provide a vacuum assisted hydraulic actuation system of the vehicle with servo booster and vacuum pump common to both clutch actuation system and the brake actuation system to reduce clutch pedal effort and brake pedal effort with fail safe.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The novel features and characteristic of the disclosure are set forth in the appended claims. The embodiments of the disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings.
Figure 1 illustrates an assembly view of a clutch pedal according to an embodiment of the present disclosure;
Figure 2 illustrates an assembly view of a mounting bracket according to an embodiment of the present disclosure;

Figure 3 illustrates a layout of a servo booster according to an embodiment of the present disclosure; and
Figure 4 illustrates an exemplary layout of a vacuum assisted hydraulic clutch actuation system according to an embodiment of the present disclosure.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific aspect disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
To overcome the drawbacks mentioned in the background, a vacuum assisted hydraulic clutch actuation system is provided with a servo booster and a vacuum pump for supplying vacuum to both a clutch actuation system and a brake actuation system to reduce a clutch pedal effort and a brake pedal effort.

Figure 1 is an exemplary embodiment of the present disclosure which illustrates an assembly view of a clutch pedal 102. The clutch pedal 102 comprises a pedal lever 104 mounted on a mounting bracket which is inside a vehicle cabin of a vehicle. The pedal lever 104 has a cutout into which a metal boss 110 is inserted, which facilitates movement of the clutch pedal 102. The metal boss 110 inserted into the cutout of the pedal lever 104 is fastened using fastening means 112 including, but are not limited to rivet bolts, bolts, screws or nuts. The pedal lever 104 comprises a pedal plate 106 mounted on its lower end. A pedal pad 108 is placed on the pedal plate for providing foot grip to a driver. A plate 114 is provided to fix up a return spring at the pedal lever 104 to retract the clutch pedal 102 back to rest after the clutch pedal 102 is released by the driver. A clutch switch bracket 116 of the clutch pedal 102 is used to mount the clutch pedal 102 on to a clutch switch mounting plate 204 (referring to figure 2) of the mounting bracket 202 (referring to figure 2) inside the vehicle cabin of the vehicle.
Figure 2 illustrates an assembly view of a mounting bracket 202 according to an embodiment of the present disclosure. The mounting bracket 202 comprises a clutch switching mounting plate 204, a left mounting bracket 206, a right mounting bracket 208, a top mounting bracket 210 and a servo booster mounting plate 212. The clutch switching mounting plate 204 is used to mount the clutch pedal 102. The left mounting bracket 206, the right mounting bracket 208, the top mounting bracket 210 together forms one rigid mounting bracket 202 for mounting the clutch pedal 102 and a servo booster using nuts 214 and tie rods 216. The servo booster mounting plate 212 has a cutout into which the servo booster is mounted using fastening means.
Figure 3 illustrates a layout of the servo booster 302 according to an embodiment of the present disclosure. The servo booster 302 is fluidically connected to the clutch pedal 102 and a brake pedal (not shown in figure 3) for assisting the clutch force and the brake force applied by the driver. The servo booster 302 is mounted onto the mounting bracket 202, between the clutch pedal 102 and a master cylinder 304. The servo booster 302 comprises an inlet vacuum channel 306 through which vacuum is supplied to the servo booster 302. The vacuum in the servo booster 302 is created by a vacuum assist port upon actuating the clutch pedal 102. The vacuum assist port is provided in the servo booster

302, which is not shown in the figure 3. The servo booster 102 consists of a hollow housing with a movable rubber diaphragm across the centre, creating two chambers. When the servo booster 102 is attached to the intake manifold of the vacuum pump, the pressure in both chambers of the servo booster is lowered. The equilibrium created by the low pressure in both chambers keeps the diaphragm from moving until the clutch pedal or the brake pedal is depressed. The return spring is fixed on the plate 114 keeps the diaphragm in the starting position until the clutch or brake pedal is applied. For example, when the clutch pedal is applied, the movement opens the inlet vacuum channel 306 through which atmospheric pressure air or vacuum is supplied to one chamber of the servo booster 302. Since the pressure becomes higher in one chamber, the diaphragm moves toward the lower pressure chamber with a force created by the area of the diaphragm and the differential pressure. This force, in addition to the driver's foot force, pushes on a master cylinder piston in the master cylinder 304. The master cylinder 304 comprises an inlet hydraulic port 308 through which hydraulic fluid are supplied from a hydraulic fluid tank (not shown) to the master cylinder 304. The master cylinder 304 further comprises an outlet hydraulic channel 310 through which the hydraulic fluid flows to a brake actuation system.
Figure 4 illustrates a layout of a vacuum assisted hydraulic clutch actuation system 402 according to an embodiment of the present disclosure. The servo booster 302 is fluidically connected to a clutch vacuum tank 404 of the clutch actuation system 402. The clutch vacuum tank 404 is used for supplying vacuum from it to the servo booster 302 through the inlet vacuum channel 306. The clutch vacuum tank 404 is electrically connected to a vacuum pump 406 for pumping vacuum from the clutch vacuum tank 404 to the servo booster 302 when the clutch pedal 102 is actuated. The vacuum pump 406 is a common to the clutch actuation system 402 and a brake actuation system 420 of the vehicle. The vacuum pump 406 is fluidically connected to the clutch vacuum tank 404 through a first non-return valve 408 and to a brake vacuum tank 422 of a brake actuation system 420 through a second non-return valve 424. The first non-return valve 408 opens up when the clutch pedal is actuated and the second non-return valve 424 upon actuating the brake pedal of the brake actuation system 420 which is fluidically connected to the

servo booster 302. The servo booster 302 is connected to the master cylinder 304 which comprises the inlet hydraulic port 308 through which it receives the hydraulic fluid from a hydraulic fluid tank (not shown). The master cylinder 304 includes a master cylinder piston (not shown) which moves to and fro with the force of the vacuum from the servo booster 302. The master cylinder 304 is hydraulically linked to a slave cylinder 412 through a hydraulic channel 410. The slave cylinder 412 is provided at the engine side of the vehicle and is attached to a clutch fork 416 through a clutch linkage 414 fixed on a transmission unit 418 of the vehicle. The slave cylinder 412 includes a slave cylinder piston (not shown) which moves to and fro with the force by the hydraulic fluid received through the hydraulic channel 410 from the master cylinder 304. The slave cylinder piston moves the clutch fork 416 which changes the gear ratio of the transmission unit 418 of the engine.
The brake actuation system 420 is fluidically connected to the master cylinder 304. Upon actuating the brake pedal, the vacuum pump 406 pumps the vacuum from the brake vacuum tank 422 to the servo booster 302. Then, the hydraulic fluid from the master cylinder 304 is supplied to the brake actuation system 420 through the outlet hydraulic channel 310. The brake vacuum tank 422 supplies vacuum to the brake actuation system through the flow line valve 426.
The working of the vacuum assisted hydraulic clutch actuation system 402 is explained herein. When the driver presses the clutch pedal 102, the first non-return valve 408 opens up and the vacuum pump 406 gets actuated which pumps the vacuum from the clutch vacuum tank 404 to the servo booster 302 through the inlet vacuum channel 304. Then, the vacuum from the servo booster 302 forces the master cylinder piston in the master cylinder 304 to move to and fro since a hydraulic pressure is created in the master cylinder 304. The master cylinder piston movement pushes the hydraulic fluid to the slave cylinder 412 where the slave cylinder is moved to and fro which in turn moves the clutch fork 416 through the clutch linkage 414. The clutch fork 416 thus changes the gear ratio of the transmission unit 418 at the engine side of the vehicle assisting clutch actuation system 402.

Similarly, when the brake pedal is applied, the second non-return valve 424 opens up. Then, the vacuum pump 406 gets actuated which pumps the vacuum from the brake vacuum tank 422 to the servo booster 302 through a channel (not shown in figure 4). The vacuum from the servo booster 302 forces the master cylinder piston in the master cylinder 304 to move to and fro since a hydraulic pressure is created in the master cylinder 304. The master cylinder piston movement pushes the hydraulic fluid to the brake actuation system 420 through the outlet hydraulic channel 310 for assisting brake actuation system 420. The brake vacuum tank 422 supplies vacuum to the brake actuation system through the flow line valve 426.
Additional features and advantages are realized through various techniques provided in the present disclosure.
Embodiment of the present disclosure provides a fail-safe system i.e. to operate the clutch actuation system 402 and the brake actuation system 420 independent of one another. More particularly, the brake actuation system 420 can be operated even if the clutch actuation system 402 fails. Similarly, the clutch actuation system 402 can be operated even if the brake actuation system 420 fails.
Equivalents
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the

absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
Referral Numerals:

Reference Number Description
102 Clutch pedal
104 Pedal lever
106 Pedal plate
108 Pedal pad
110 Metal boss
112 Fastening means
114 Plate
116 Clutch switch bracket
202 Mounting bracket
204 Clutch switching mounting plate
206 Left mounting bracket
208 Right mounting bracket
210 Top mounting bracket
212 Servo booster mounting plate
302 Servo booster
304 Master cylinder
306 Inlet vacuum tank
308 Inlet hydraulic port
310 Outlet vacuum channel
402 Clutch actuation system
404 Clutch vacuum tank
406 Vacuum pump
408 First non-return valve

410
Hydraulic channel
412 Slave cylinder
414 Clutch linkage
416 Clutch fork
418 Transmission unit
420 Brake actuation system
422 Brake vacuum tank
424 Second non-return valve
426 Flow line valve

We claim:
1. A vacuum assisted hydraulic clutch actuation system comprising:
a clutch pedal mounted on a mounting bracket inside a vehicle cabin;
a servo booster mounted onto the mounting bracket between the clutch pedal and a master cylinder, said servo booster comprises an inlet vacuum channel through which vacuum is supplied to the servo booster;
a vacuum assist port provided in the servo booster for creating vacuum in the servo booster when the clutch pedal is actuated;
a clutch vacuum tank fluidically connected to the servo booster to supply vacuum from the clutch vacuum tank to the servo booster through the inlet vacuum channel; and
a vacuum pump electrically connected to the servo booster for pumping vacuum from the clutch vacuum tank to the servo booster when the clutch pedal is actuated, wherein the vacuum pump is a common to the clutch actuation system and a brake actuation system of a vehicle which is fluidically connected to the clutch vacuum tank through a first non-return valve and a brake vacuum tank of a brake actuation system through a second non-return valve;
when the clutch pedal is actuated, a hydraulic pressure is created in the master cylinder by means of vacuum pumped from the clutch vacuum tank by the vacuum pump, said master cylinder supplies hydraulic fluid to a slave cylinder provided at an engine side of the vehicle for assisting clutch actuation.
2. The system as claimed in claim 1, wherein the master cylinder comprises an inlet hydraulic port through which hydraulic fluid is supplied from a hydraulic fluid tank to the master cylinder.
3. The system as claimed in claim 1, wherein the slave cylinder is attached to a clutch fork through a clutch linkage fixed on a transmission of the vehicle.
4. The system as claimed in claim 1, wherein the first non-return valve opens upon actuating the clutch pedal.

5. The system as claimed in claim 1, wherein the servo booster is fluidically connected to a brake pedal.
6. The system as claimed in claim 1, wherein the vacuum pump pumps the vacuum from the brake vacuum tank to the servo booster when the brake pedal is actuated.
7. The system as claimed in claim 1, wherein the brake vacuum tank supplies vacuum to the brake actuation system through a flow line valve.
8. The system as claimed in claim 1, wherein the brake actuation system is fluidically connected to the master cylinder.
9. The system as claimed in claim 1, wherein the second non-return valve opens upon actuating the brake pedal.
10. A method of assisting a vacuum assisted hydraulic clutch actuation system comprising:
generating a hydraulic pressure in a master cylinder by means of vacuum pumped from a clutch vacuum tank to a servo booster through an inlet vacuum channel, said clutch vacuum tank is fluidically connected to the servo booster for supplying vacuum to the servo booster pumped by a vacuum pump which is a common to the clutch actuation system and brake actuation system of a vehicle which is fluidically connected to the clutch vacuum tank through a first non-return valve and a brake vacuum tank through a second non-return valve, wherein vacuum in the servo booster is created by a vacuum assist port provided in the servo booster when a clutch pedal is actuated; and
supplying hydraulic fluid from the master cylinder to a slave cylinder provided at an engine side of the vehicle for assisting clutch actuation.