Claims:We claim:

1 A master cylinder assembly (1000B) for a motor vehicle comprising of:
- a brake lever (101),
- a brake fluid reservoir (102),
- a master piston (109) within a master cylinder bore (108),
- a non-return valve (105),
- a non-return valve spring (107), and
- a stopper bolt (104a),
wherein said stopper bolt (104a) has a hollow chamber (104ad) which provides an oil flow path (130) between fluid reservoir (102) and master cylinder bore (108) within its surface area.

2 The master cylinder assembly (1000B) for a motor vehicle as claimed in claim 1, wherein said stopper bolt (104a) has a stopper bolt head (104ab) and a stopper bolt thread (104ac) portion with a slit (140a) arrangement.

3 The master cylinder assembly (1000B) for a motor vehicle as claimed in claim 1, wherein said stopper bolt (104a) has a stopper bolt head (104ab) and a stopper bolt thread (104ac) portion with a hole (140b) arrangement.

4 The master cylinder assembly (1000B) for a motor vehicle as claimed in claim 2, wherein said slit (140a) is present in said stopper bolt head (104ab) portion.

5 The master cylinder assembly (1000B) for a motor vehicle as claimed in claim 3, wherein said hole (140b) is present in said stopper bolt head (104ab) portion.

6 The master cylinder assembly (1000B) for a motor vehicle as claimed in claim 1, wherein the master piston (109) has a non-return valve resting groove (150) for resting O ring (114) facilitating to improve the life of O ring (114).

7 The master cylinder assembly (1000B) for a motor vehicle as claimed in claim 4 or 5, wherein the profile of the bolt head (104ab) is selected from a group of various options viz. circular, square, pentagonal, hexagonal or any of polygonal profile fulfilling the functional requirement

Dated 31st day of July 2020

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

To,
The Controller General of Patents,
Intellectual Property Office, at Mumbai , Description:FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“MASTER CYLINDER ASSEMBLY FOR MOTOR VEHICLE”

Endurance Technologies Limited
E-92, M.I.D.C. Industrial Area, Waluj, Aurangabad – 431136
Maharashtra, India

The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of Invention

[001] The present invention is related to a master cylinder assembly of a hydraulic drum or disc brake in a motor vehicle. More particularly, the present invention is related to a unique oil flow path between fluid reservoir and master cylinder bore of master cylinder assembly of brake system of a motor vehicle.

Background of the Invention

[002] In a braking system of a vehicle, particularly two wheeled vehicles, the mechanical effort applied at brake lever by the user, is being converted by the master cylinder to hydraulic pressure by feeding brake fluid into the brake circuit and controlling this according to the mechanical force. It multiples the force applied by the vehicle rider on the brake lever and transmits the same to the piston inside the master cylinder bore. The complete arrangement of the brake master cylinder, along with its intricate components plays the vital role in transferring the brake pressure to the foundation brakes at the wheels. In this arrangement, there is generally a replenishing / feeding hole connecting the master cylinder bore with the fluid reservoir, which allows the hydraulic fluid flow from the hydraulic fluid reservoir to master cylinder bore and thereby ensures the smooth functioning of the brake.

[003] In the prior art document No. EP 0518 375 B1, the master cylinder arrangement comprises of a replenishing / feeding hole which acts as the fluid flow path between the fluid reservoir and the master cylinder bore. The construction of this replenishing / feeding hole results in loose burr formation, which eventually results in wear and tear of the seals inside the master cylinder.

[004] Also in case where the replenishing / feeding hole is present, there is a restriction on the piston stroke length such that the secondary seal should not be crossing the replenishing / feeding hole in the full stroke condition, else there are again chances of seal wear and tear.

[005] Hence, in light of the various limitations of the prior art solutions available in the public domain, there is long pending unmet need to provide a novel and technically superior master cylinder assembly of brake system of a motor vehicle with a unique oil flow path between fluid reservoir and master cylinder bore which can be manufactured with uncomplicated structures.

Objects of the Present Invention

[006] The main object of the present invention is to provide a novel master cylinder assembly of brake system of a motor vehicle with a unique oil flow path between fluid reservoir and master cylinder bore.

[007] Another object of the present invention is to provide a master cylinder assembly of brake system that eliminates the need of a separate replenishing / feeding hole.

[008] Still further object of the present invention to provide a master cylinder assembly of brake system wherein the said assembly has a stopper bolt encompassing oil flow passage.

[009] Yet, further object of the present invention is to provide a novel master cylinder assembly of brake system that facilitates the user/rider of vehicle to apply optimal braking force as there is no restriction of replenishing/feeding hole position on selecting the total piston strokes.

[0010] Yet, another object of the present invention is to provide a novel master cylinder assembly of brake system that effectively prevents wear and tear of piston seal; is easy to manufacture and economic in nature.

Summary of the Invention

[0011] In order to achieve the above objects, the present invention provides a master cylinder assembly which eliminates the need of a separate replenishing/feeding hole. The stopper bolt in the present invention is provided with a slit or a hole in the stopper bolt head portion. This slit or hole communicates with a hollow chamber which allowing the smooth oil flow between the fluid reservoir and master cylinder bore by providing an oil flow passage through the same. This in turn eliminates the requirement of a separate drilling operation requirement for making the replenishing / feeding hole and also eliminates the burr formation. Said arrangement in turn eliminates the chances of seal cuts due to the friction between seals and loose machining burrs. The slit or a hole so provided in the stopper bolt head portion also increases the use of dead oil volume from the fluid chamber.

[0012] Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.

Brief Description of the Drawings

[0013] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein and advantages thereof will be better understood from the following description when read with reference to the following drawings, wherein

[0014] Figure 1 discloses the brake master cylinder assembly for a motor vehicle as present in the prior art.

[0015] Figure 2a illustrates the master cylinder assembly of brake system for a motor vehicle in accordance with the present invention.

[0016] Figure 2b describes the master cylinder assembly of brake system for a motor vehicle depicting the oil flow path through the stopper bolt in accordance with the present invention.

[0017] Figure 3a and 3b illustrates the sectional view of the stopper bolt in accordance with the present invention with its two variants viz. with slit and hole, respectively.

[0018] Figure 4a and 4b shows the perspective view of the stopper bolt in accordance with the present invention with slit and hole, respectively.

[0019] Figure 5a and 5b illustrates the non-return valve section representing two operating conditions, brake OFF position and brake ON position, of operation of the non-return valve as per the present invention.

Detailed Description of the Present Invention

[0020] The invention will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.

[0021] The Figure 1 depicts the master cylinder assembly (1000A) in accordance with the prior art prevailing. The whole arrangement comprises of a brake lever (101) which works to activate the brake mechanism when force is applied on it by the rider of the vehicle. In the non-working state, the non-return valve (105) remains in contact with the stopper bolt (104). In this condition, oil from reservoir (102) is connected to master cylinder bore through replenishing/feeding hole (120) and through the space between valve and piston hole to pressure chamber. As the brake lever (101) is actuated, the force of actuation gets transferred to the piston actuator (103) which thereafter transfers the force to the master piston (109). The linear forward movement of the master piston (109) also moves the primary lip seal (112) and the secondary lip seal (116) along with it. This in turn displaces the O-ring (114) towards the non-return valve (105), moves the non-return valve (105) from the stopper bolt (104) and releases the compressed non-return valve spring (107). This movement thereby closes the oil flow path through the non-return valve (105) and isolates the replenishing/feeding chamber from pressure chamber. Due to this linear piston movement, oil in the pressurized fluid chamber (122) gets compressed thereby generates the pressure which thereby get transferred to the calliper via the outlet port (118) and thus the brakes get applied.

[0022] The Figures 2a and 2b describes the master cylinder assembly (1000B) in accordance with the present invention. Said master cylinder assembly (1000B) eliminates the requirement of the replenishing hole (120), and instead has a stopper bolt (104a) having a hollow chamber (104ad) (as given in figure 3a and 3b). Said hollow chamber (104ad) in said stopper bolt (104a) itself makes the oil flow path (130) from the fluid reservoir (102) to the master cylinder bore (108). This structure helps retain the same size of master cylinder assembly (1000B) for various stroke lengths which would otherwise have to be changed in presence of said (replenishing/feeding) hole (120) as that present in the prior art. The hollow chamber (104ad) in said stopper bolt (104a) lets optimum amount of oil flow, thereby keeps the braking performance intact.

[0023] In Figure 2b, a non-return valve section (200) is indicated with a dotted lines. The expanded view of the non-return valve section (200) is given in Figure 5a and Figure 5b. The Figure 5a and 5b clearly indicate a non-return valve resting groove (150) provided on the master piston (109) Figure 5b shows the non-return valve section (200) when the brake is in its ‘ON’ condition. This condition corresponds to the situation when the rider has operated the brake lever (101). When the brake is applied, the non-return valve (105) after compressing an O-ring (114) to a limited extent, comes to rest firmly on a non-return valve resting groove (150). This prevents any leakage of brake fluid pressure across the non-return valve (105) during application of the brake. Figure 5a shows the non-return valve section (200) when the brake is in its ‘OFF’ condition. This condition corresponds to the situation when the rider after operating the brake has withdrawn the force applied on the brake lever (101). As the piston (109) moves back under the restoring force provided by the piston return spring (106), a pressure difference is created which creates sufficient force to overcome the restoring force provided by the non – return valve spring (107) and lift the non-return valve (105) off from the non-return valve resting groove (150). This allows the brake fluid to flow past the non-return valve (105) thereby preventing a vacuum from being created in the braking system. The existence of the non-return valve resting groove (150) increases the life of the O-ring (114) by preventing it from getting damaged by the repeated excessive compressive impacts of the non- return valve (105) during operation of the braking system.

[0024] The Figure 3a and 4a depicts the cross sectional and isometric view respectively of the stopper bolt (104a) in accordance with the present invention. The stopper bolt (104a) has stopper bolt head (104ab) portion and stopper bolt thread (104ac) portion. The hollow chamber (104ad) is provided through the length of stopper bolt (104a) which makes the oil flow path (130a) from the fluid reservoir (102) to the master cylinder bore (108). A slit (140a) is provided at the stopper bolt head (104ab) portion particularly to reduce the dead oil volume.

[0025] Similarly the Figure 3b and 4b depicts the cross sectional and isometric view respectively of the stopper bolt (104a) in accordance with the present invention which has a hole (140b) at the stopper bolt head (104ab) portion making the oil flow path (130b). Said slit (140a) or the hole (140b) so provided increases the usable oil volume thereby reducing the dead volume facilitating to maintain the health of the brake. Referring to Figs. 4a and 4b, the profile of the bolt head (104ab) is selected from a group of various options viz. circular, square, pentagonal, hexagonal or any of polygonal profile fulfilling the functional requirement. However, the most preferred profile of bolt head (104ab) is hexagonal.

[0026] The technical advancements offered by the present disclosure include:
- The present invention results in elimination of drilling and machining operation which would otherwise be required in case of a separate replenishing/feeding hole.
- The present invention ensures smooth supply of brake oil during brake operation.
- It also strengthens the structure as there is no requirement of drilling the hole for oil passage.
- The space created by elimination of separate hole can be used for providing ribbing pattern to strengthening the structure and at the same time lowering the weight of the structure.
- Increased durability of seals by eliminating the chances of seal cut due to loose machining burr present with a drilled hole as the machining burr is very difficult to remove due to limited access for burr removal.

[0027] List of Reference Numerals
101- Brake Lever
102- Fluid Reservoir
103- Piston Actuator
104, 104a- Stopper Bolt
104ab- Stopper Bolt Head
104ac- Stopper Bolt Thread
104ad- Hollow Chamber
105- Non-Return Valve
106 - Piston Return Spring
107- Non-Return Valve Spring
108- Master Cylinder Bore
109- Master Piston
110- Cap
112- Primary Lip Seal
114- O-ring
116- Secondary Seal
118- Outlet Port
120- Replenishing/Feeding Hole
130a, 130b- Oil Flow Path
140a- Slit
140b- Hole
150- Non-Return Valve Resting Groove
200- Non-Return Valve Section
1000A- Master Cylinder Assembly as in Prior Art
1000B- Master Cylinder Assembly as in Present Invention

[0028] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.