Patent Application
20230365112
This application claims priority of Indian patent application no. 202241027019, filed May 10, 2022, the entire content of which is incorporated herein by reference.
The disclosure relates to a brake actuator for a vehicle, the brake actuator including a cylinder housing having a surface and a wall opening provided in the surface, a brake chamber having a variable volume, a dust plug being releasably arranged in the wall opening, the dust plug including a flexible circumferential lip configured for abutting against the surface of the cylinder housing in a sealing state, and for being flexed away from the surface in a flexed state, wherein the lip is configured to assume the flexed state in response to a positive pressure inside the brake chamber, and to assume the sealing state in response to negative pressure inside the brake chamber, and a core section being arranged adjacent to the lip, wherein the core section is configured for extending through the wall opening of the cylinder housing, a pressure compensation flow path that is defined between the lip and the brake chamber.
Brake actuators, in particular parking or emergency brake actuators, of the aforementioned type are generally known in the art. As such, they may be configured as spring brake actuators including a parking brake portion and a spring brake portion, as well as an electro-mechanical actuator. Typically, the actuators include a cylinder housing including a wall opening for inserting a so-called release bolt. Such a release bolt is utilized to manually disengage the parking brake portion of the actuator. During normal vehicle operation, the release bolt is removed from the wall opening. To prevent dust or water from entering the actuator, the wall opening is closed with a dust plug.
When the parking brake is released, a pressure larger than the ambient pressure builds up in the spring chamber that needs to evade from the housing. In order to achieve this, known dust plugs include a slot arranged in the periphery of the dust plug through which the overpressure may evade from the brake chamber. The evading pressure flexes the lip from the cylinder housing. In other words, a gap is created between the lip and the cylinder housing, when pressure is evaded, which may allow dust or water enter the brake chamber. This is highly unwanted.
In view thereof, it is an object of the disclosure to improve the brake actuator of the initially mentioned type to overcome the deficiencies found in the prior art as much as possible. In particular, it was an object of the disclosure to provide an improved brake actuator which is less susceptible to dust and water entry into the brake chamber and which is easy to install and manufacture.
The disclosure attains the aforementioned objects by providing a brake actuator of the initially mentioned type, wherein the core section includes a circumferential baffle wall, the flow path includes a passage opening extending from the surface through the cylinder housing and the pressure compensation flow path has a first flow path section extending from the lip to the passage opening and a second flow path section extending from the passage opening along the baffle wall,
The disclosure is based upon the realization that instead of providing a flow path through the dust plug, by guiding the flow path through the cylinder housing and by deflecting the flow by means of the baffle wall, the probability is highly reduced that dust or water unwantedly enter the brake chamber. In particular when the actuator is mounted horizontally, water and dust may enter the passage opening but will be guided with the help of the flow path out of the brake actuator without entering the brake chamber.
The dust plug, the surface and the wall opening are preferably dimensioned such that matter entering the flow path from the outside of the cylinder housing is deflected by the baffle wall away from the brake chamber. Preferably, the lip is configured to sealingly close the pressure compensation flow path when in the sealing state, and to open the pressure compensation flow path when in the flexed state. In other words, the combination of cylinder and dust plug works as a check valve.
According to an embodiment, the passage opening is formed at an outside diameter of the wall opening. In this way, a well-defined flow path is defined directly adjacent to the dust plug.
According to yet another embodiment, the passage opening is a first passage opening and the spring brake actuator includes a second passage opening arranged at the outside diameter of the wall opening, wherein the second opening is arranged opposite from the first opening, such that the flow diverted by the baffle wall is guided towards a second passage opening.
Thereby, a flow of water or dust that enters the cylinder housing via, for example, the first passage opening, is deflected by the baffle wall and thereafter guided along the baffle wall towards the second passage opening, at which the dust or water may exit the cylinder housing again. In this way, the probability of water or dust entering the brake chamber is further minimized.
In another embodiment, the passage opening is arranged spaced apart from the wall opening. In other words, the passage opening forms a separate opening with respect to the wall opening. While providing the same benefits with regard to the entry of dust or water, such a configuration may be easier to assemble or to retrofit.
According to yet another embodiment, the passage opening is a first passage opening and the spring brake actuator includes a second passage opening arranged spaced apart from the outside diameter of the wall opening, wherein the first opening is arranged opposite from the second opening, such that the flow diverted by the baffle wall is guided towards the second passage opening.
With this configuration, again, entering dust or water is guided through the first opening via the baffle wall towards the second compensation opening and thereafter out of the housing.
According to yet another embodiment, the passage openings are arranged on a diameter coaxial to the longitudinal axis of the cylinder housing. In this way, the flow characteristics through and out of the compensation openings are unified.
According to yet another embodiment, the at least one passage opening includes, at least partially, a circular outer cross section. This cross section has been found to be beneficial to allow for a convenient pressure compensation, while at the same time, the probability of dust or water entering the cylinder housing is minimized. In case however dust or water enter the housing, the configuration facilitates the water or dust exiting the housing via the passage openings.
According to yet another embodiment, the core section includes at least one circumferential bead for providing an interference fit with the wall opening of the cylinder housing. The bead not only provides an interference fit with the wall opening but is also beneficial in guiding water or dust that have unwantedly entered the cylinder housing out of the housing again. Preferably, the bead is part of the baffle wall.
According to another embodiment, the core section includes a flexible flange section being arranged adjacent to the core section, the flange section including a diameter larger than a diameter of the core section for providing a snap fit connection with the cylinder housing. The flange allows for a convenient assembly and disassembly of the dust plug. Furthermore, the flange portion of the dust plug may also facilitate guiding dust or water through the housing and away from the brake chamber.
According to yet another embodiment, the dust plug includes a reinforcement structure for improving the structural rigidity of the dust plug. According to yet another embodiment, the reinforcement structure includes two stiffening elements, the two stiffening elements forming a cross-shaped structure. The reinforcement structure helps preventing the dust plug from being dislocated when air passes along the dust plug. Furthermore, the reinforcement structure allows for a more compact configuration of the dust plug.
In a further aspect, the disclosure relates to a dust plug for insertion into in a wall opening of a cylinder housing of a spring brake actuator, the dust plug including: a flexible circumferential lip covering a compensation flow path fluidly connecting a brake chamber with an outside of the actuator, the lip configured for abutting against a section of the cylinder housing, wherein the lip is deflected from the cylinder housing when pressure from the brake chamber exhausts through the pressure compensation flow path, and a core section being arranged adjacent to the lip, wherein the core section is configured for engaging with the wall opening of the cylinder housing, wherein the core section includes a baffle wall.
According to an embodiment, the core section includes at least one circumferential bead for providing an interference fit with the wall opening of the cylinder housing.
According to yet another embodiment, the core section includes a flexible flange section being arranged adjacent to the core section, the flange section including a diameter larger than a diameter of the core section for providing a snap fit connection with the cylinder housing. Preferably, the dust plug includes a reinforcement structure for improving the structural rigidity of the dust plug.
The dust plug takes advantage of the same benefits and embodiments as the spring brake actuator according to the disclosure and vice versa. In this regard and in order to avoid unnecessary repetitions, reference is made to the above explanations.
The invention will now be described with reference to the drawings wherein:
The spring brake 48 furthermore includes a spring brake piston 12 located in the cylinder housing 4 for applying a braking force and a compression spring 14 arranged between the spring seat 10 and the spring brake piston 12, the compression spring 14 being effective to push the spring brake piston 12 away from the cylinder housing base 8.
The cylinder housing 4 is divided into a brake chamber/spring chamber 16 and a pressure chamber 18. The compression spring 14 is arranged in the spring chamber 16. The pressure chamber 18 is supplied with pressurized fluid. The spring chamber 16 is separated from the pressure chamber 18 by a diaphragm 44. The cylinder housing 4 is attached to a housing section 46 which may have the form of a flange.
The brake actuator 2 furthermore includes a passage opening 40 which is arranged in the cylinder housing 4. The cylinder housing 4 moreover includes a wall opening 20. The wall opening 20 is configured for accommodating a release bolt (not shown). During normal operation, a dust plug 22 is releasably arranged in the wall opening 20. The dust plug 22 includes a flexible circumferential lip 28. The flexible circumferential lip 28 covers the passage opening 40. The lip 28 is configured for abutting against a section 30 of the cylinder housing 4 that includes the passage opening 40. The lip 28 gets deflected from the cylinder housing 4 when pressure evades from the spring chamber 16 through the passage opening 40. Moreover, a sealing element 42 is arranged between the spring seat 10 and the cylinder housing 4.
The service brake section 50 includes a service brake piston 52 which is moved against the force of a service brake compression spring 54 by pressure inside the service brake chamber 56. The spring brake actuator 2 may be attached to the vehicle by means of mounting bolts 58.
In other words, the flexible circumferential lip 28 is configured for abutting against the surface 9 of the cylinder housing 4 in a sealing state, and for being flexed away from the surface 9 in a flexed state. The lip 28 is configured to assume the flexed state in response to deflected from the cylinder housing 4 when a positive pressure from inside the brake chamber 16 exhausts through the pressure compensation flow path 40, and to assume the sealing state in response to negative pressure inside the brake chamber 16. A core section 32 is arranged adjacent to the lip 28. The core section 32 is configured for engaging extending through with the wall opening 20 of the cylinder housing 4. A pressure compensation flow path 35 is defined between the lip 28 and the brake chamber 16.
The core section 32 includes a circumferential baffle wall 33. The flow path 35 includes a passage opening 40 extending from the surface 9 through the cylinder housing 4 and the pressure compensation opening flow path 35 has a first flow path section 43 extending from the lip 28 to the passage opening 40 and the radial baffle wall 33 delimiting and a second flow path section 45 extending from the passage opening 40 along the baffle wall 33.
The second flow path 35 section is arranged at an angle 47 relative to the first flow path section 43, preferably orthogonally, such that matter entering the flow path 35 from the outside of the cylinder housing 4 is deflected by the baffle wall 33 away from the brake chamber 16.
It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202241027019 | May 2022 | IN | national |
