DESC:TECHNICAL FIELD
The present invention relates to a brake system with hydraulic circuit for actuating in-board parking brake circuit.
It provides parking brake system for motor vehicles and more particularly to complete hydraulic actuated parking brake system and method thereof.

BACKGROUND
It is known to equip motor vehicles such as automobiles, trucks and the like, with a park brake for static use, i.e. for use to hold the vehicle in a stationary position while parked. In certain circumstances a park brake can be applied dynamically, e.g., during vehicle travel, e.g., in an emergency situation where the primary brakes fail, as a hill-hold device to hold a vehicles position while shifting gears on a hill with a standard transmission, etc. Traditionally, a park brake actuator is mounted in the passenger compartment of the vehicle for manual operation, e.g., hand or foot operation by the vehicle's operator. The manual actuator is typically either a pull-on hand-operated lever-type handle or a push-on foot-operated lever-type pedal. In certain typical systems pulling upward on the park brake lever applies the park brake via a mechanical linkage to the brake mechanism. For example, certain known

mechanical park brakes utilize a cable or other mechanical linkage to operatively connect the manual actuator in the passenger compartment to the operating components of the park brake, e.g., brake calipers, drum brake shoes or the like at the wheels, external brake bands or internal brake shoes mounted elsewhere on the drive line. Alternatively, park brake systems can use, for example, air brakes, e.g., systems utilizing an air-controlled spring system that co-operates with brake shoes at a vehicle's wheels. In operating such park brakes greater pulling (or pushing) force on the lever or other actuator typically results in correspondingly greater park brake force being applied.
Earlier in the same equipment parking brake was disc and caliper type situated on the input flange of rear axle and the actuation circuit was pneumatic type. Existing system is with pneumatic type of actuation which involves air boosters, air cylinders and air valves applicable to rear axle with disc type external parking brake. Rear axle with in-board parking brake is installed into the same equipment which is having higher volume per actuation compared to previous external type for enhancing the braking effectiveness. The pneumatic system for higher volume axle presents design limitations in terms of sizing the components and engineering of pneumatic components on equipment due

to space constraints. The application volume and pressure is less in case of existing system.
Hence, in order to increase the effectiveness of the braking and to change the actuation circuit completely from air system to hydraulic system, the present invention provides the brake assembly in which brakes are made as a part of rear axle assembly and the actuation circuit is fully hydraulic type.
SUMMARY
According to an embodiment of the present invention, there is provided a complete hydraulic actuated parking brake system and method. The hydraulic braking power uses oil to transfer pressure from the controlling mechanism to the braking mechanism as it is an in-compressible fluid and delivers maximum force, controlled and smoother braking experience. The hydraulic actuated parking brake comprises of components such as pump, control valve for pump stroke and de-stroke, accumulator as potential for releasing the parking brake, solenoid actuated cartridge valve for actuating parking brake and throttle or dump valve to release the potential stored in accumulator during servicing the pressure lines.
The pump is loaded as and when potential is required in the accumulator for actuation and gets unloaded when the potential is achieved in accumulator

thereby saving the energy consumed by the pump and preventing the overheating of the hydraulic system due to continuous loading of pump.

BRIEF DESCRIPTION OF THE DRAWING
The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings.
Fig. 1 is the flow diagram depicting the working of the hydraulic circuit actuated parking brake system according to the present invention

DESCRIPTION BASED ON DRAWING
In the following detailed description, reference is made to the accompanying drawing which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural and logical changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by

the appended claims and their equivalents.
Various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Moreover, all statements herein reciting embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition and persons in the pertinent art have given that term as reflected in printed

publications and issued patents at the time of filing.
According to an embodiment of the present invention, system and method is provided for hydraulic power actuating of parking brake of motor vehicle.
The present invention utilizes fully hydraulic power to actuate parking brake in which oil is an in-compressible fluid and delivers maximum work as compared to pneumatic type actuators. The present invention converts the parking brake actuation circuit from air system to hydraulic system. As a result it ensures, effectiveness of parking brake system providing maximum force and pressure while applying brakes.
The hydraulic circuit comprises of components such as pump, control valve for pump stroke and de-stroke, accumulator as potential for releasing the parking brake, solenoid actuated cartridge valve for actuating parking brake and throttle or dump valve to release the potential stored in accumulator during servicing the pressure lines. It deploys accumulator assisted parking brake actuation circuit.
Fig. 1 is the hydraulic block diagram that depicts components involved in the circuit. There is a dedicated brake pump (1) in the circuit which draws oil from the hydraulic tank (2) and delivers it to brake valve (4) through filter (3) which charges the accumulator (5). Once the accumulator charges completely, the brake valve opens the relieving port (6) and diverts the pump delivered oil

back to tank with no-load condition on pump. It means that pump is loaded as and when potential is required in the accumulator (5) for actuation and gets unloaded when the potential is achieved in accumulator (5) thereby saving the energy consumed by the pump and preventing the overheating of hydraulic system due to continuous loading of pump.
After attaining accumulator potential, solenoid operated cartridge valve (7) is operated electrically to release or apply the parking brake (8,8’). External accumulator charging provision (9) is also provided in the system in the event of failure of brake pump (1) . Manual dump option (10) is available in the circuit during servicing/ maintenance time to remove the potential from Accumulator (5).
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 appended claims.
,CLAIMS:1. A brake system with hydraulic circuit for actuating in-board parking brake circuit to increase the effectiveness of the braking and to change the actuation circuit completely from air system to hydraulic system, wherein brakes are made as a part of rear axle assembly and the actuation circuit is fully hydraulic type said brake system comprises of a dedicated brake pump (1) in the circuit which draws oil from the hydraulic tank (2) and delivers it to brake valve (4) through filter (3) which charges the accumulator (5) once the accumulator charges completely, the brake valve opens the relieving port (6) and diverts the pump delivered oil back to tank with no-load condition on pump; pump is loaded as and when potential is required in the accumulator (5) for actuation and gets unloaded when the potential is achieved in accumulator (5) thereby saving the energy consumed by the pump and preventing the overheating of hydraulic system due to continuous loading of pump; after attaining accumulator potential, solenoid operated cartridge valve (7) is operated electrically to release or apply the parking brake (8, 8’).

2. A brake system as claimed in claim 1 wherein external accumulator charging provision (9) is also provided in the system in the event of failure of brake pump (1).

3. A brake system as claimed in claim 2 wherein manual dump option (10) is available in the circuit during maintenance time to remove the potential from Accumulator (5).