Description:FIELD OF THE INVENTION
[001] The present invention generally relates to a master cylinder assembly. More particularly, the present invention relates to a hydraulic brake master cylinder assembly.

BACKGROUND OF THE INVENTION
[002] Conventionally, in a vehicle, existing hydraulic brake master cylinder assembly is normally fitted with a single open-coiled compression spring for providing return force for the movement of a brake lever. As a result of provision of the single open-coiled compression spring, the brake lever or brake pedal has a very small amount of movement to actuate in addition to having very small free play. More particularly, after a small free play region or region of ineffective stroke of the movement of the brake lever, wherein the movement of the brake lever is not causing any braking effect.
[003] Such conventional configurations lead to poor efficiency of transmission in hydraulic braking system, lower brake performance in terms of lever input and brake lever torque, sluggish or vague braking behaviour, delay and poor control in braking response, all of which leads to user safety and fatigue concerns. A poor brake response also makes it difficult for a user to recover from a skid like condition. The safety and fatigue concerns are especially prominent in high speed, high traffic and poor road conditions. Poor brake returnability, in which a brake does not easily return to its original position, can also cause issues such as excess drag on the vehicle which leads to lowered fuel economy and high temperatures of the brake disc.
[004] Thus, in master cylinder assemblies that use a single open-coiled compression spring, it becomes necessary to provide a spring which not only has the required stiffness in braking return, while having the required spring pre load. Even if the above two characteristics are achieved, the single open-coiled compression spring remains susceptible to buckling, which would severely affect the braking performance.
[005] Thus, there is a need in the art for a master cylinder assembly which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[006] In one aspect, the present invention relates to a master cylinder assembly. The master cylinder assembly has a housing. The housing is configured to receive a piston. The piston moves in a brake operating condition, wherein the piston is connected to an elastic member assembly. The elastic member assembly includes a plurality of elastic members.
[007] In an embodiment of the invention, the piston is connected to a brake lever and the piston is configured to move in response to the movement of the brake lever for displacing fluid.
[008] In an embodiment of the invention, the housing includes a compression chamber. The compression chamber is configured for receiving brake fluid from a reservoir chamber and transmitting brake fluid to an outlet port.
[009] In a further embodiment of the invention, the elastic member assembly is provided in the compression chamber and is operably connected to the piston. The return spring assembly has the plurality of elastic members being connected in series, and one or more connectors. Each connector is provided between adjacent elastic members thereby connecting the plurality of elastic members in a series, wherein each of the plurality of elastic members are disposed along a common axis.
[010] In a further embodiment of the invention, the plurality of elastic members include a first spring and a second spring connected in series, and the connector is provided between the first spring and the second spring.
[011] In a further embodiment of the invention, the first spring is connected to the housing and the connector, and the second spring is connected to the connector and the piston.
[012] In a further embodiment of the invention, the connector has a rim portion having a circular profile, and a hub portion provided radially inward and extending axially from the rim portion.
[013] In a further embodiment of the invention, the first spring is a telescopic spring having a base end and an apex end. A cross section area of the first spring at the base end is greater than a cross section area of the first spring at the apex end. In an embodiment, the base end of the first spring is connected to the housing and the apex end of the first spring is connected to the hub portion of the connector. The hub portion extends axially from the rim portion towards the piston.
[014] In a further embodiment of the invention, the second spring is a telescopic spring having a base end and an apex end. A cross section area of the second spring at the base end is greater than a cross section area of the second spring at the apex end. In an embodiment, the base end of the second spring is connected to the rim portion of the connector, and the apex end of the second spring being connected to the piston.
[015] In a further embodiment of the invention, the first spring is a barrel spring having a first end and a second end. The first end of the first spring is connected to the housing, and the second end of the first spring is connected to the rim portion of the connector.
[016] In a further embodiment of the invention, the second spring is a barrel spring having a first end and a second end, and the cross-section area of the second spring is smaller than the first spring. The first end of the second spring is connected to the hub portion of the connector and the hub portion extends axially from the rim portion away from the piston. The second end of the second spring is connected to the piston.

BRIEF DESCRIPTION OF THE DRAWINGS
[017] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 illustrates a sectional view of a master cylinder assembly, in accordance with an embodiment of the invention.
Figure 2A illustrates a sectional view of an elastic member assembly of the master cylinder assembly, in accordance with an embodiment of the invention.
Figure 2B illustrates an exploded view of an elastic member assembly of the master cylinder assembly, in accordance with an embodiment of the invention.
Figure 3 illustrates an exploded sectional view of the master cylinder assembly, in accordance with an alternative embodiment of the invention.
Figure 4A-4E illustrate graphical representation of lever load vs lever travel in the present invention in comparison to the conventional system, in accordance with an embodiment of the present invention.
Figure 5 illustrates another sectional view of the master cylinder assembly, in accordance with an embodiment of the invention.
Figure 6 illustrates another sectional view of the master cylinder assembly, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[018] The present invention relates to a master cylinder assembly. In particular, the present invention relates to a hydraulic brake master cylinder assembly. The master cylinder assembly of the present invention is typically used in a vehicle such as a two wheeled vehicle. However, it should be understood that the master cylinder assembly as illustrated may find its application in a three wheeled vehicle, or a four wheeled vehicle, or other multi-wheeled vehicles, or any non-automotive application using a hydraulic brake as required.
[019] Figure 1 illustrates a sectional view of a master cylinder assembly 100 in accordance with an embodiment of the present invention. As illustrated in Figure 1, the master cylinder assembly 100 comprises a housing 130. The housing 130 houses all the components of the master cylinder assembly 100 and is provided at a position which is close to a brake lever position. For example, in a two wheeled vehicle, the housing 130 is provided on a handlebar of the two wheeled vehicle.
[020] As illustrated, the housing 130 is configured to receive a piston 110, wherein the piston 110 moves in a brake operating condition. Thus, whenever the brake is to be operated, the piston 110 moves thereby allowing a brake fluid present inside the different parts of the housing to move, for application of the hydraulic brake (not shown). For facilitating the smooth movement and the return movement of the piston 110, the piston 110 is connected to an elastic member assembly 150. The elastic member assembly 150 includes a plurality of elastic members 160. Herein, when the piston 110 moves in a braking operation, the plurality of elastic members 160 get compressed and provide the required resistance and smoothness in the movement of the piston 110. When the piston 110 is to move to its original position, the compression force of the plurality of elastic members 160 provide expansion force to the piston 110, as the elastic members 160 return to their normal state. As a result of provision of a plurality of elastic members 160, a free play time and range in the movement of the piston 110 is increased and improved, thereby improving overall braking characteristics.
[021] In an embodiment of the invention, the piston 110 is connected to a brake lever (not shown), and the piston 110 is configured to move in response to the movement of the brake lever for displacing brake fluid. Thus, whenever the user desires to apply brakes, the user moves the brake lever, in response to which the piston 110 moves, thereby displacing brake fluid for a braking operation. As further illustrated in the embodiment depicted in Figure 1, the housing 130 includes a compression chamber 120. During a braking operation, the compression chamber 120 is configured for receiving brake fluid from a reservoir chamber 140 and transmitting brake fluid to an outlet port 132. The compressed or pressurised brake fluid is then transmitted to a brake calliper through the outlet port 132 to activate the brake calliper and perform the braking operation.
[022] As further illustrated in the embodiment depicted in Figure 1 and Figure 2A, the elastic member assembly 150 is provided in the compression chamber 120 and being operably connected to the piston 110. Thus, for the movement of the piston 110, the elastic member assembly 150 gets compressed and relaxed inside the compression chamber 120. As illustrated, the elastic member assembly 150 has the plurality of elastic members 160 being connected in series. The elastic member assembly 150 further comprises one or more connectors 170. In that, each connector 170 is provided between adjacent elastic members 160 thereby connecting the plurality of elastic members 160 in a series. By virtue of the plurality of elastic members 160 being connected in series, a higher overall length of elastic members 160 is achieved, which allows for a higher range of free play. As illustrated in Figure 2A, each of the plurality of elastic members 160 are disposed along a common axis X-X’.
[023] As further illustrated in Figure 1 and Figure 2A, in an embodiment, the plurality of elastic members 160 comprise a first spring 162 and a second spring 164 connected in series. Herein, the connector 170 is provided between the first spring 162 and the second spring 164. As illustrated, the first spring 162 is connected to the housing 130 and the connector 170, and the second spring 164 is connected to the connector 170 and the piston 110. Thus, the movement of the brake lever is transmitted to the piston 110, and the movement of the piston 110 causes compression in the second spring 164. The compression in the second spring 164 is transmitted to the first spring 162 through the connector 170. The spring connector 170 ensures that the first spring 162 and the second spring 164 to have deflection without buckling and thereby accommodates a longer overall free length of combined first spring 162 and the second spring 164. This allows for higher overall compression / deflection ratios.
[024] To further provide sufficient support to the first spring 162 and the second spring 164, as illustrated in Figure 2B, the connector 170 comprises a rim portion 172 having a circular profile, and a hub portion 174 provided radially inward and extending axially from the rim portion 172. One out of the first spring 162 or the second spring 164 is supported on the rim portion 172, and the other of the first spring 162 or the second spring 164 is supported on the radially inward hub portion 174. Such a configuration ensures that the compression from the second spring 164 is evenly distributed along the connector 170 and then transmitted to the first spring 162 or vice versa. This also ensures that neither of the first spring 162 or the second spring 164 remain susceptible to buckling.
[025] In an embodiment, as depicted in Figure 1 and Figure 2A, the first spring 162 is a telescopic spring having a base end 162A and an apex end 162A’, wherein a cross section area of the first spring 162 at the base end 162A is greater than a cross section area of the first spring 162 at the apex end 162A’. In this embodiment, the base end 162A of the first spring 162 being connected to the housing 130 and the apex end 162A’ of the first spring 162 is connected to the hub portion 174 of the connector 170. As illustrated, the hub portion 174 extends axially from the rim portion 172 towards the piston 110.
[026] Further, the second spring 164 is a telescopic spring having a base end 164A and an apex end 164A’, wherein a cross section area of the second spring 164 at the base end 164A is greater than a cross section area of the second spring 164 at the apex end 164A’. In this embodiment, the base end 164A of the second spring 164 is connected to the rim portion 172 of the connector 170 and the apex end 164A’ of the second spring 164 is connected to the piston 110. Thus, in this configuration, the connector 170 supports the apex end 162A’ of the first spring 162 at the axially extending hub portion 174, and the supports the base end 164A of the second spring at the rim portion 172.
[027] Such a configuration allows for some overlap between the first spring 162 and the second spring 164, while ensuring that both the hub portion 174 and the rim portion 172 of the connector 170 provide support, which further reduces the chances of buckling of the springs. For example, if the first spring 162 starts to buckle, the resultant twisting movement of the hub portion 174 would be resisted by the second spring 164 connected to the rim portion 172. Similarly, if the second spring 164 starts to buckle, the resultant twisting movement of the rim portion 172 would be resisted by the first spring 162 connected to the hub portion 172.
[028] In an embodiment as referenced in Figure 5, the connector 170 further comprises an anti friction or resilient guide member 180. The guide member 180 is configured to be in contact with the inner wall of the compression chamber 120 for resisting the movement of the connector 170 or any rotation of the connector 170, thereby preventing buckling of the first spring 162 and the second spring 164. In an alternate embodiment as referenced in Figure 6, the connector 170 comprises double anti friction or resilient guide members 180 for resisting the movement of the connector 170 or any rotation of the connector 170, thereby preventing buckling of the first spring 162 and the second spring 164.
[029] In an alternative embodiment of the invention, as illustrated in Figure 3, the first spring 162 is a barrel spring having a first end 162B and a second end 162B’. Herein the first end 162B of the first spring 162 is connected to the housing 130 and the second end 162B’ of the first spring 162 is connected to the rim portion 172 of the connector 170.
[030] Further, the second spring 164 is a barrel spring having a first end 164B and a second end 162B’. As illustrated, in this embodiment, the cross section area of the second spring 164 is smaller than the first spring 162. As illustrated in Figure 3, the first end 164B of the second spring 164 is connected to the hub portion 174 of the spring connector 170. Herein, the hub portion 174 extends axially from the rim portion 172 away from the piston 110. As illustrated in Figure 3, the connector 170 in this embodiment has a substantially U-shaped cross section. Further, the second end 164B’ of the second spring 164 being connected to the piston 110. Such a configuration allows for some overlap between the first spring 162 and the second spring 164, while ensuring that both the hub portion 174 and the rim portion 172 of the connector 170 provide support, which further reduces the chances of buckling of the springs, while ensuring uniform transfer of compression force between the first spring 162 and the second spring 164.
[031] As a result of the present invention, as can be seen in Figures 4A-4E, which illustrates a curve between the brake lever travel and brake lever load. Herein, curve L1 illustrates the curve for the prior art and the curve L2 represents the curve for the present invention. The free play of the brake lever, i.e. the range of motion of the brake lever for the braking operation to start, is higher in the present invention (illustrated as X2) as compared to the prior art (illustrated as X1), as a result of which the braking characteristics are improved. Specifically, as illustrated in Figure 4A, in the present invention, not only is the free play of the brake lever increased as compared to the prior art, but also the level of lever load (represented by A1 for prior art and A2 for the present invention) required for actuation of the brakes is minimised in the present invention as compared to the prior art thus reducing the effort required for braking and stress on the brake lever.
[032] Further, as specifically illustrated in Figure 4B, the brake is actuated or the braking operation is started at a higher level of lever travel in the present invention as compared to the prior art, thereby leading to lower loss (represented by B1 for prior art and B2 for the present invention) for braking operation in the present invention as compared to the conventional system. The higher level of lever travel minimises the risk of sudden braking or jerks, but also provides more predictable and consistent braking feel. Further, as specifically illustrated in Figure 4C, in case of a sudden or hard braking, the lever load in case of hard braking is lower in the present invention, thereby leading to lower lever load (represented by C1 for prior art and C2 for the present invention) and less stress on the braking system in braking operation for sudden or hard braking.
[033] As specifically illustrated in Figure 4D and 4E, in the present invention, to initiate the braking operation, a higher lever travel is required and a lower lever of lever load is sufficient, as compared to the prior art wherein only a lower lever travel is achieved, and the lever load is also higher. Thus, the loss of energy in actuation of the brakes (represented by D1 for prior art and D2 for the present invention in Figure 4D, and represented by E1 for prior art and E2 for the present invention in Figure 4E) in the present invention is also lower than loss of energy in actuation of brakes in the prior art.
[034] Advantageously, the present invention provides a master cylinder assembly in which a connector is provided to bridge a plurality of springs to compress. It allows an increase in overall number of coils, free spring length and pre-compression, and in increasing overall compression ratio. The present invention allows for very low overall spring stiffness, which results in enhancement or increasing of range of continuous movement of the brake lever and a higher range of free play.
[035] Further, the present invention also achieves elimination of any buckling effect by lateral guiding support provided by the connector. This ensures maintenance of higher transmission efficiency, positive brake returnability, and compact packaging in size.
[036] As a result, better efficiency in the transmission of the brake system is achieved, in addition to improved brake performance in terms of brake torque and braking force. This also leads to elimination of sluggish or vague braking feel, reduces delay in braking response and improves user control in braking. Thus, better user comfort and reduction in user fatigue is also achieved by the present invention. The consistent braking feel also improvise user confidence and allows the user to recover from a skid like situation with more ease, thus leading to improved user safety. Further, the adequate return of the brake lever also ensures that the brakes are fully disengaged, and there is no unnecessary drag on the vehicle, thus preventing overheating of brakes and improving fuel efficiency.
[037] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

List of Reference Numerals
100: Master Cylinder Assembly
110: Piston
120: Compression Chamber
130: Housing
132: Outlet Port
140: Reservoir Chamber
150: Elastic Member Assembly
160: Plurality of Elastic Members
162: First Spring
162A: Base End of First Spring
162A’: Apex End of First Spring
162B: First End of First Spring
162B’: Second End of First Spring
164: Second Spring
164A: Base End of Second Spring
164A’: Apex End of Second Spring
164B: First End of Second Spring
164B’: Second End of Second Spring
170: Connector
172: Rim Portion
174: Hub Portion
180: Guide Members
, Claims:WE CLAIM:
1. A master cylinder assembly (100), comprising:
a housing (130), said housing (130) being configured to receive a piston (110), said piston (110) moving in a brake operating condition,
wherein said piston (110) being connected to an elastic member assembly (150), said elastic member assembly (150) includes a plurality of elastic members (160).

2. The master cylinder assembly (100) as claimed in claim 1, wherein the piston (110) being connected to a brake lever, the piston (110) being configured to move in response to the movement of the brake lever for displacing fluid.

3. The master cylinder assembly (100) as claimed in claim 1, wherein said housing (130) includes a compression chamber (120), the compression chamber (120) configured for receiving brake fluid from a reservoir chamber (140) and transmitting brake fluid to an outlet port (132).

4. The master cylinder assembly (100) as claimed in claim 1, wherein the elastic member assembly (150) being provided in the compression chamber (120) and being operably connected to the piston (110), the elastic member assembly (150) comprising the plurality of elastic members (160) being connected in series; and one or more connectors (170), each connector (170) being provided between adjacent elastic members (160) thereby connecting the plurality of elastic members (160) in a series, wherein each of the plurality of elastic members (160) are disposed along a common axis (X-X’).

5. The master cylinder assembly (100) as claimed in claim 4, wherein the plurality of elastic members (160) comprise a first spring (162) and a second spring (164) connected in series, and the connector (170) being provided between the first spring (162) and the second spring (164).

6. The master cylinder assembly (100) as claimed in claim 5, wherein the first spring (162) is connected to the housing (130) and the connector (170), and the second spring (164) is connected to the connector (170) and the piston (110).

7. The master cylinder assembly (100) as claimed in claim 6, wherein the connector (170) comprises a rim portion (172) having a circular profile, and a hub portion (174) provided radially inward and extending axially from the rim portion (172).

8. The master cylinder assembly (100) as claimed in claim 7, wherein the first spring (162) is a telescopic spring having a base end (162A) and an apex end (162A’), wherein a cross section area of the first spring (162) at the base end (162A) is greater than a cross section area of the first spring (162) at the apex end (162A’).

9. The master cylinder assembly (100) as claimed in claim 8, wherein the base end (162A) of the first spring (162) being connected to the housing (130) and the apex end (162A’) of the first spring (162) being connected to the hub portion (174) of the connector (170), wherein the hub portion (174) extends axially from the rim portion (172) towards the piston (110).

10. The master cylinder assembly (100) as claimed in claim 7, wherein the second spring (164) is a telescopic spring having a base end (164A) and an apex end (164A’), wherein a cross section area of the second spring (164) at the base end (164A) is greater than a cross section area of the second spring (164) at the apex end (164A’).

11. The master cylinder assembly (100) as claimed in claim 10, wherein the base end (164A) of the second spring (164) being connected to the rim portion (172) of the connector (170), and the apex end (164A’) of the second spring (164) being connected to the piston (110).

12. The master cylinder assembly (100) as claimed in claim 7, wherein the first spring (162) is a barrel spring having a first end (162B) and a second end (162B’), wherein the first end (162B) of the first spring (162) being connected to the housing (130), and the second end (162B’) of the first spring (162) being connected to the rim portion (172) of the connector (170).

13. The master cylinder assembly (100) as claimed in claim 7, wherein the second spring (164) is a barrel spring having a first end (164B) and a second end (162B’), and the cross section area of the second spring (164) being smaller than the first spring (162), and wherein the first end (164B) of the second spring (164) being connected to the hub portion (174) of the connector (170), wherein the hub portion (174) extends axially from the rim portion (172) away from the piston (110), and the second end (164B’) of the second spring (164) being connected to the piston (110).