DESC:PRIORITY CLAIM:
[0001] This application claims priority from the provisional application numbered 202041009257 filed with Indian Patent Office, Chennai on 4th March 2020 entitled “An assembly for mechanical actuation of disk brakes of automotive vehicles”, the entirety of which is expressly incorporated herein by reference.
PREAMBLE TO THE DESCRIPTION:
[0002] The following specification describes the invention:
DESCRIPTION OF THE INVENTION:
Technical field of the invention
[0003] The present invention relates in general to an assembly that enables the mechanical actuation of disk brakes in automotive vehicles. The present invention in particular relates to an assembly for the actuation of the disk brakes in automotive vehicles by means of a mechanical mechanism to provide a reliable, robust and cheaper method of actuation of disk brakes.
Background of the invention
[0004] The present assemblies for actuation of disk brakes are largely hydraulic in nature. The assemblies require hydraulic fluid to operate, which is often expensive. In addition to cost of purchase, hydraulic fluid also requires to be routinely filtered such that impurities in the hydraulic fluid are removed to ensure the smooth working of the hydraulic fluid. Dust, grime and other impurities tend to get accumulated in the hydraulic fluid and thus the hydraulic fluid requires additional systems for maintenance of the hydraulic fluid, further increasing the complexity and cost of the assembly. Braking assemblies are disposed at close proximity to the rotating wheels of automotive vehicles, which in turn are at close proximity to the exterior of the automotive vehicle, thus exposed to conditions that allow easy susceptibility to dust and dirt. Hydraulic fluid is an active component in present disk brake assemblies and involves a significant of relative motion between the components of the disk brake assembly by virtue of engagement and disengagement of the disk brakes. This relative motion and dynamic nature of hydraulic disk brake assemblies may cause fractures or cracks in the disk brake assembly, which may circulate in the hydraulic systems of the disk brake assembly, leading to an increase in concentration of impurities in the hydraulic fluid and subsequently leading to a need for filters and cleaning systems.
[0005] The present assemblies for actuation of disk brakes utilize hydraulic fluid for actuation, wherein the hydraulic fluid may also undergo alteration to its physical parameters such as viscosity and homogeneity. This change in physical parameters occurs due to repeated use of the hydraulic fluid. The repeated loading and unloading of the disk brake system corresponds to cyclic loads on the hydraulic fluid, this altering its physical parameters. In such an event, it becomes a matter of urgency to change the hydraulic fluid entirely so as to not compromise the functioning of the disk brake assembly. Hydraulic fluid at sub-optimal viscosity could lead to not enough force being generated at the disk brake pads for braking effect, or it could result in the user applying sufficient braking force at the input side of the disk brake system but the force not being transmitted effectively to the disk brake pads due to high viscosity of the hydraulic fluid. Due to this, it is required that the hydraulic fluid be replaced, which further raises the cost of the disk brake assembly. Additionally, hydraulic fluid needs to be stored in a storage tank where the fluid is kept as a reserve when the disk brake assembly is not in operation. This results in a need to install bulky systems for braking needs in automotive systems.
[0006] The patent application number JP2004239331A titled “Disk brake device with parking brake mechanism” discloses an invention to make operation feeling and braking force of a parking brake mechanism compatible with each other, and to facilitate the routing of cable for operating the parking brake mechanism. In a disc brake device with a parking brake mechanism, a lever shaft is connected to an operation cable and is rotatably provided on a holding arm of a brake calliper, and rotation of the lever shaft is controlled by a cam mechanism. The force is converted into thrust of the piston through the relay piston and thrust of the piston presses the friction pads against the brake disk to generate braking force.
[0007] Hence, there is a need for as assembly for mechanical actuation of a disk brake for automotive vehicles.
Summary of the invention:
[0008] The present invention provides an assembly for mechanical actuation of disk brakes of automotive vehicles. The present invention comprises a housing unit fitted with an end cap to securely house the components of the assembly. The assembly further comprises a user-actuated cam lever which rotates through a pre-defined angle when actuated. The cam lever is connected to a cam, wherein rotary movement of the cam lever is converted to translatory movement of the cam by means of cam lever protrusions and cam grooves. The cam transmits translatory movement to a piston which applies force on brake pads such that the brake pads come into contact with a brake disk to produce a braking effect in the assembly.
[0009] The assembly comprises a return spring connected to the brake pads and piston to ensure that the force of the piston on the brake pads is uniform in nature. Additionally, the assembly comprises a guide shaft upon which the cam, piston and return spring are mounted to maintain concentricity of the components, thereby ensuring that the assembly operates as intended. The assembly further comprises a dust cover to prevent clogging agents from entering the assembly and an adjuster for altering the amount of braking force between the brake disk and brake pads. The adjuster is also used to adjust the amount of distance between the brake disk and brake pads to compensate for reduction of thickness of the brake pads during operation of the assembly.
[0010] The present invention overcomes the drawbacks encountered in prior arts by providing an assembly for mechanical actuation of disk brakes of automotive vehicles. The present invention provides an assembly that operates without hydraulics and pneumatics, thus eliminating the need for maintenance and filtration of hydraulic brake fluid used in conventional brake assemblies. Further, the absence of hydraulic fluid in the present invention also leads to a more reliable and robust brake assembly, which requires less maintenance, reducing operating costs of the present invention. The present invention is additionally relatively more robust and reliable due to a purely mechanical design, resulting in a brake assembly that is less prone to breaking down. Further, the dust cover housed in the assembly ensures that there is significantly less susceptibility of the assembly to external impurities.
Brief description of the drawings:
[0011] The foregoing and other features of embodiments will become more apparent from the following detailed description of embodiments when read in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like elements.
[0012] FIG 1 illustrates an assembly for mechanical actuation of disk brakes of automotive vehicles.
[0013] FIG 2 illustrates the cam lever of an assembly for mechanical actuation of disk brakes of automotive vehicles.
[0014] FIG 3 illustrates the cam of an assembly for mechanical actuation of disk brakes of automotive vehicles.
Detailed description of the invention:
[0015] Reference will now be made in detail to the description of the present subject matter, one or more examples of which are shown in figures. Each example is provided to explain the subject matter and not a limitation. Various changes and modifications obvious to one skilled in the art to which the invention pertains are deemed to be within the spirit, scope and contemplation of the invention.
[0016] The present invention relates to an assembly comprising a housing unit and end cap for housing the assembly. The assembly comprises a cam lever which actuates the cam lever when operated, which in turn actuates a cam housed within the assembly. The cam pushes a piston towards the brake pads of the assembly and thus engage the brake disk to provide a braking effect. A return spring ensures that identical braking forces are encountered in the assembly a guide shaft ensures that the cam and piston are held concentrically in the assembly. The assembly also comprises an adjuster which adjusts the amount of contact force in the assembly.
[0017] FIG 1 illustrates an assembly (100) for mechanical actuation of disk brakes in automotive vehicles. The assembly (100) comprises a housing unit (101) and end cap (102) within which the components of the assembly (100) are arranged to provide a protective cover for the components of the assembly (100). The housing unit (101) provides structural support for the assembly (100) and has provisions for easy fitment of the assembly (100) with the rest of the automotive vehicle. The end cap (102) fits into the housing unit (101) and together with the housing unit (101) forms the external cover of the assembly (100). In a preferred embodiment of the present invention, the housing unit (101) and end cap (102) are held in place by at least one fastening mechanism which may be a screw. The assembly (100) also comprises a cam lever (103) whose upper end is mechanically connected to the brake cable or lever of automotive vehicles. The cam lever (103) is actuated when the user of the automotive vehicle operates the brake cable or lever. The operation of the brake cable or lever causes the cam lever (103) to rotate about its lower end through a small angle. The lower end of the cam lever (103) has one or more cam lever protrusions (103a, FIG 2). The lower end of the cam lever (103) is connected to a cam (104) that has one or more cam grooves (104a, FIG 3) etched into it. The profile of the cam grooves (104a) facilitates the conversion of the rotatory motion of the cam lever protrusions (103a) at the lower end of the cam lever (103) into translatory motion of the cam (104). The cam (104) has a fixed degree of rotation which prevents it from rotating when the cam lever (103) rotates within the cam (104).
[0018] FIG 2 illustrates the cam lever (103) with one or more cam lever protrusions (103a). The cam lever protrusions (103a) are designed to take the shear stress that develop when the cam lever (103) interacts with the cam (104). The cam lever protrusions (103a) may also comprise protrusions, rollers, wedges and so on in other embodiments of the present invention. The cam lever protrusions (103a) are responsible for transferring the torque of the cam lever (103) to the cam (104) in order to operate the assembly (100).
[0019] FIG 3 illustrates the cam (104) with one or more cam grooves (104a), corresponding to the number of cam lever protrusions (103a) on the cam lever (103). The cam grooves (104a) have a sloping inner profile that meshes with the cam lever protrusions (103a). The sloping inner profile of the cam grooves (104a) is responsible for converting the rotary torque of the cam lever (103) to translatory motion of the cam (104). This translatory motion is transmitted to the piston (105) which engages the assembly (100) to cause a braking effect.
[0020] The lower end of the cam lever (103) has one or more cam lever protrusions (103a) that are inserted into one or more corresponding cam grooves (104a) of the cam (104). The cam grooves (104a) have a sloping inner profile wherein when the cam lever (103) is fully disengaged with respect to the cam (104), the cam groove (104a) is at maximum depth. At the fully engaged position, the cam grooves (104a) are at minimum depth. Between these two extremities of depth, the inner profile of the cam grooves (104a) slopes to provide a smooth elevation for the cam lever protrusions (103a). When the cam lever (103) is in the fully disengaged position, the lower end of the cam lever (103) and cam (104) are in their closest proximity. As the lower end of the cam lever (103) is rotated, the cam lever protrusions (103a) move within the cam grooves (104a). The cam grooves (104a) allow the cam lever protrusions (103a) to rotate within the cam grooves (104a), but the sloping profile gradually increases the distance between the cam lever (103) and cam (104). The cam lever (103) is rigidly held in the assembly (100) and is thus unable to move. The cam (104) however, is only rotationally constrained. The interaction between the cam lever protrusions (103a) and cam grooves (104a) causes the cam (104) to move away from the cam lever (103). This results in the cam (104) being displaced parallel to its central axis, thus facilitating the conversion of rotary motion of the lower end of the cam lever (103) into translatory motion of the cam (104).
[0021] The cam (104) is placed in contact with a piston (105) such that they have similar degrees of freedom. The cam (104) moves along its central axis due to the interaction between the cam lever protrusions (103a) and cam grooves (104a) and subsequently applies a force on the piston (105). This causes the piston (105) to move in the same direction as the cam (104) and come into contact with one of the two brake pads of the assembly (100). Due to the significantly large torque arm of the cam lever (103), the amount of force applied at the upper end of the cam lever (103) gets proportionally increased as it is transmitted to the brake pad, enabling the user of the automotive vehicle to apply a moderate amount of force on the brake cable or lever and consequently obtain a much higher amount of force at the brake pad, which applies a prohibitive force on the brake disk to produce the braking effect due to friction between the brake pads and brake disk.
[0022] The assembly (100) also comprises a return spring (106) that is arranged around the piston (105). The return spring (106) opposes the motion of the piston (105) and cam (104) and ensures that the cam (104) returns to the original disengaged position when the user of the automotive vehicle releases the brake cable or lever. When the force applied by the cam (104) on the piston (105) due to the interaction between the cam lever protrusions (103a) and cam grooves (104a) is more than the force applied by the return spring (106), the cam (104) pushes against the return spring (106) to push the piston (105) and engage the brake pad to cause braking effect. When the force exerted by the return spring (106) is greater than the force exerted by the cam (104) on the piston (105), the piston (105) pushes the cam (104) back. The cam (104) then pushes the cam lever (103) back into the disengaged position.
[0023] The brake pads positions are not fixed in the housing unit (101). Once the piston (105) has fully pushed one of the brake pads against the brake disk, the constant force of the cam (104) against the brake disk causes the housing unit (101) to retract slightly, enabling the second brake pad to come into contact with the brake disk. In this way, the flexibility of movement of the brake pads in the housing unit (101) ensures that both brake pads apply equal and simultaneous prohibitive force on the brake disk. The assembly (100) further comprises a guide shaft (107) attached to the end cap (102). The lower end of the cam lever (103), cam (104) and piston (105) are concentrically mounted on the guide shaft (107) to ensure that there is no undesirable relative motion and that concentricity is maintained between the moving components of the assembly (100). A dust cover (108) is disposed at the base of the cam lever (103) to prevent the entry of external corrosive and erosive agents during the operation of the assembly (100). The dust cover (108) ensures that the internal moving components of the assembly (100) continue to function as intended and do not get damaged prematurely.
[0024] The assembly (100) further comprises an adjuster (109) attached to the end cap (102). In one embodiment, the adjuster (109) is a bolt which ensures appropriate contact force between the brake pads and brake disk of the assembly (100). When tightened, the adjuster (109) reduces the distance between the brake pads and brake disk. This is useful when the brake pads of the assembly (100) get worn out due to frictional losses during brake action of the assembly (100) and reduce in thickness. To compensate for the loss in thickness of the brake pads, the adjuster (109) is tightened, thus ensuring that the distance between the brake pads and brake disk is optimal. The adjuster (109) comprises an indication on its surface which acts as a guidance point to display when the adjuster (109) needs to be tightened and to what degree. The tightening of the adjuster is done by using a mechanism connected to the adjuster (109). In a preferred embodiment of the present invention, the mechanism to tighten the adjuster (109) comprises a locknut mechanism mounted concentrically with respect to the adjuster (109). The locknut mechanism is disposed outside of the end cap (102) and may be tightened or loosened to compensate for loss of brake pad thickness. Additionally, the adjuster (109) may become loose with respect to the assembly (100) due to usage of the assembly (100). To maintain optimal contact force between the brake disk and brake pads, the locknut mechanism may be tightened. The components of the assembly (100) are constructed from mechanically rigid materials to enhance the robustness and reliability of the assembly (100).
[0025] The present invention provides an assembly (100) for the mechanical actuation of disk brakes of automotive vehicles, thereby eliminating many shortcomings associated with hydraulic disk braking systems. The usage of a purely mechanical assembly (100) eliminates extra overhead costs such as fluid filtration systems, fluid storage tanks and spare hydraulic fluid. Due to the assembly (100) comprising mechanical components, there is a high degree of reliability and robustness in the assembly (100) which is hard to achieve in hydraulic systems as usage of hydraulic fluid may result in leakages, leading to loss of fluid and thus unreliability. The mechanical components are also immune to deterioration over time if designed appropriately, as opposed to hydraulic systems in which the hydraulic fluid inevitably loses physical properties during the operation of the system. The dust cover (108) ensures that there are no corrosive or erosive agents present in the assembly (100), thus eliminating the possibility of deterioration in the assembly (100). All these features ensure that the present invention is robust, reliable and immune to deterioration from external forces.
[0026] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist.
Reference numbers:
Components Reference Numbers
Assembly 100
Housing unit 101
End cap 102
Cam lever 103
Cam lever protrusion 103a
Cam 104
Cam groove 104a
Piston 105
Return Spring 106
Guide shaft 107
Dust cover 108
Adjuster 109

,CLAIMS:We claim:
1. An assembly (100) for mechanically engaging the disk braking system of automotive vehicles, the assembly (100) comprising:
a. a housing unit (101) to provide structural rigidity and protection for the components of the assembly (100) and to protect the components of the assembly (100) from external agents of erosion and corrosion;
b. an end cap (102) assembled with the housing unit (101) to provide a protective cover for the components of the assembly (100) and to protect the components of the assembly (100) from external agents of erosion and corrosion;
c. a cam lever (103) housed within the housing unit (101) and end cap (102), wherein the cam lever (103) comprises cam lever protrusions (103a) and rotates about its lower end through a pre-defined angle when actuated;
d. a cam (104) mechanically connected to the cam lever (103), wherein the cam (104) comprises cam grooves (104a) and is laterally displaced when the cam lever (103) is actuated;
e. a piston (105) disposed at one end of the cam (104), wherein the piston (105) moves in a lateral direction when the cam (104) is laterally displaced;
f. a return spring (106) disposed between the cam (104) and piston (105), wherein the return spring (106) ensures that the assembly (100) applies identical amount of braking force on a brake disk of the assembly (100);
g. a guide shaft (107) upon which the cam (104), piston (105) and return spring (106) are concentrically mounted, thereby ensuring the proper functioning of the assembly (100);
h. a dust cover (108) disposed at the base of the cam lever (103) to prevent clogging agents from entering the assembly (100);
i. an adjuster (109) housed within the end cap (102) to adjust the amount of contact force between brake disk and brake pads of the assembly (100).

2. The assembly (100) as claimed in claim 1, wherein a brake cable is connected between the cam lever (103) and a user-operated brake lever for the purpose of braking.

3. The assembly (100) as claimed in claim 1, wherein the assembly (100) comprises brake pads which are mechanically connected to the piston (105) to create a braking effect on the brake disk of the assembly (100).

4. The assembly (100) as claimed in claim 1, wherein the assembly (100) comprises a fastening mechanism connected to the adjuster (109) to maintain the contact force between brake disk and brake pads of the assembly (100).