Field of the invention
The present invention relates to "Master cylinder for rear disc brake" and more particularly to an integrated oil reservoir with master cylinder for disc brake for two and three wheelers.
Description of the prior art
Generally, a master cylinder-reservoir assembly 101 for rear brake (figure 1) in two and three wheelers comprises a housing 102 provided with bore with piston, primary lip seal, a secondary lip seal, a piston return spring, an internal cir-clip, a protection boot 103, filler union and grommet (not shown). A separate oil reservoir assembly comprises a reservoir body 104, a reservoir cap 105 and a diaphragm. The master cylinder assembly 101 and the oil reservoir assembly are connected through reservoir tube 106 with the help of hose clamp 107 at both ends. Piston connected with pushrod 108 connected by fork 109 can be operated by actuating the operating pedal. Pressing or actuating the brake pedal moves a push rod 108 in the master cylinder 110. A piston that is mounted on the push rod exerts force against the fluid in the master cylinder bore. The pressure created displaces fluid through the hose 111 connected to master cylinder and a calliper to each of the wheels and applies the brakes. The assembly 110 is secured through mounting holes 112 on the motorcycle at a suitable location such as swing arm, etc.
Currently available master cylinders possess shortcomings, having a separate oil reservoir 104 connected by reservoir tube 106 and hose clamps 107 at both ends mounting at two different places. Further assembly of components is also difficult and typically requires lot of time. Additionally, multiple parts such as O-rings, fasteners etc. are required to hold the assembly in position Packaging constraints

are also encountered in mounting. Additionally, in prior art the oil reservoir 104 and the master cylinder 110 are secured using a variety of means such as bolting, etc. But this further increases the number of parts, difficulty in assembling, leakage, etc. Further, once they are secured, chances are there that diaphragm and the reservoir cap 105 leaks due to uneven level of oil beneath them. Further, filling the reservoir becomes tough owing to an inclined nature of the reservoir 104.
Hence to obviate the lacunae prior art the first objective of the present invention is to provide an integrated reservoir-master cylinder assembly. Another objective of the present invention is also to provide an assembly that is easy to secure, consumes less number of parts and avoids leakage and address oil levelling issues.
Brief description of the invention
An integrated master cylinder further comprising a reservoir inclined at mounting having a piston assembly which can be actuated by a foot pedal. The integrated master cylinder is constructed such that the reservoir cap and the diaphragm separately are parallel to the horizontal axis of the vehicle. Another feature of the present invention is the integral nature of the master cylinder -reservoir assembly. The total assembly comes in one piece instead of separate components jointed together. In other words, the integrated reservoir is directly inbuilt on the master cylinder. An oil window is also arranged to mark the minimum oil level with a reflector.

Brief description of the drawings
Figure 1 illustrates a master cylinder assembly according to the prior art.
Figure 2 illustrates a disc brake assembly according to the present invention.
Figure 3 illustrates integrated master cylinder assembly according to the present invention.
Detailed description of the invention
The basic parts of a disc brake 201 are a rotor 202 and hub 203 and a calliper assembly (figure 2). The rotor 202 provides the friction surface for stopping the wheel. The rotor 202 has a machined braking surface on each side. The wheel is mounted to the rotor hub 203 by wheel lug nuts and studs 204. The hub houses wheel bearings (not shown) that allow the wheel to freely rotate while keeping it centred on its axle.
The disc brake caliper converts hydraulic pressure from the master cylinder 205 to mechanical force that pushes the brake pads against the rotor. The calliper is mounted over the rotor. Although there are many design differences among calipers, all calipers 204 have a calliper body, or housing 206, hydraulic lines and internal hydraulic passages, one or more pistons, piston seals, and dust boots. A brake line 207 from the master cylinder is attached to the caliper housing. When the brakes are applied, fluid under pressure from the master cylinder 205 enters the caliper housing 206. The caliper has at least one large hydraulic piston (not shown) located in a piston bore. During braking, fluid pressure behind the piston increases. Pressure is exerted equally against the botton of the piston and the bottom of the cylinder bore.

The pressure applied to the piston is transmitted to the inboard brake pad to force the lining against the inboard rotor surface. Depending on the caliper 204 design, fluid pressure can be routed to matching pistons on the outboard side of the caliper, or the pressure applied to the bottom of the cylinder 205 can force the caliper to move inboard on its mount. In either case, the caliper applies mechanical force equally to the pads on both sides of the rotor to stop the motorcycle.
The present invention relates to an integrated master cylinder assembly (figure 2 and figure 3) comprising a master cylinder body 205 that defines a reservoir 208 storing a working fluid and having housing provided with bore in which a piston assembly works. The piston assembly comprises a piston 209, a primary lip seal 210, a secondary lip seal 211, a piston return spring 212 such that the piston is returned elastically to its original position of rest, an internal circlip 213 that locks the piston
moment from master cylinder bore 224, and a protection boot 214 that protects the
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system from dust and foreign particles. A reservoir cap 215 is also provided along with a diaphragm 216 to protect the oil and to avoid leakage. Piston connected with a pushrod 217 that is further connected by fork 225 can be operated by actuating the operating pedal 222. A threaded outer cover 220 tightened to the master cylinder body 221 provides housing for pretension spring 218 and washer 219 and holds the pushrod 217 at pre installed load.
When the brake pedal 222 is actuated or depressed, the spring loaded piston assembly pushes the push rod 217 which further pushes the piston 209. The piston 209 forces the fluid into the brake hose 207 until all the brake hose clearance has been taken up. Additional thrust on the pedal 222 then pressurizes the hydraulic system and forces each of the brake to actuate the brake calipers 204. When the brake peclal 222 is released, the spring loaded piston assembly in the master

cylinder 221 returns to its rest position. The fluid that was displaced by the piston 209 is pushed back to the master cylinder 221 as the disc brake pads retract, and
the fluid returns to the fluid reservoir 208 through the compensating ports 223.
The integrated master cylinder further comprises a reservoir 208 inclined at
mounting 224 having a piston assembly which can be actuated by a foot pedal 222.
The integrated master cylinder 205 is constructed such that the reservoir cap 215
and the diaphragm 216 separately are parallel to the horizontal axis of the vehicle.
Another feature of the present invention is the integral nature of the master cylinder -
reservoir assembly. The total assembly comes in one piece instead of separate
components jointed together. In other words, the integrated reservoir is directly
inbuilt on the master cylinder. An oil window is also arranged to mark the minimum
oil level with a reflector.
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.

Claims
We claim:
1. An integrated master cylinder assembly for a disc brake comprising:
a master cylinder body defining a reservoir storing a working fluid and having a housing provided with a bore having a piston assembly; and a reservoir cap along with diaphragm mounted on said reservoir.
2. The integrated master cylinder assembly for a disc brake as claimed in claimed 1, wherein said reservoir cap and said diaphragm separately are parallel to the horizontal axis of the vehicle.
3. The integrated master cylinder assembly for a disc brake as claimed in claimed 1, wherein said piston assembly comprises a piston connected with a push road that is further connected by a fork operated by actuating a foot pedal, a primary lip seal, a secondary lip seal, a piston return spring, an internal circlip and a protection boot.
4. The integrated master cylinder assembly for a disc brake as claimed in claimed 1, wherein said master cylinder and said reservoir are integrated into a unitary piece.
5. A two wheeler or having the integrated master cylinder assembly for a disc brake as claimed in claim 1.
6. A three wheeler or having the integrated master cylinder assembly for a disc brake as claimed in claim 1.