FIELD OF INVENTION
Brake chamber is an auto component used in the brake system of commercial vehicles. It is fitted on the front axle of buses & Trucks and axles of Trailer. Brake chamber is an assembly consisting of formed steel components, rubber diaphragm, spring, clamp, fasteners, etc., A typical brake chamber is illustrated in fig. 1. To produce the braking force at the foundation brakes using compressed air is the main function of the brake chamber.
When the driver applies brake by foot pedal, compressed air from the brake valve through rubber hose enters the brake chamber. Air pressure builds up inside the chamber and pushes the diaphragm and push rod out. The push rod in turn actuates the slack adjuster and brake cam shaft is rotated to expand the shoes to brake the drum or wheel. This is illustrated in fig. 2.
The present invention is for
a) Brake chambers
b) Service chamber of Spring Brake Actuators
and it relates to the prevention of dust, dirt, water entry through breather holes by using one-way vales (flap type).
PRIOR ART :
The brake chamber at each wheel converts a'tr pressure to mechanical motion. When air enters the air inlet, it moves the diaphragm which moves the push rod. The push rod of the brake chamber is connected to a slack adjuster. The slack adjuster serves two functions; firstly to change the back and forth motion of the push rod to rotary motion and further to make adjustments to compensate for lining wear. The slack adjuster is splined to one end of a shaft that goes through the backing plate of the wheel brake. The other end of the shaft contains a cam. When the brake chamber push rod moves the end of the slack adjuster, it causes the shaft to rotate.

As the cam on the brake end of the shaft rotates, it causes the brake shoes with the lining to move against the drum. Minor adjustment of the brake is made by rotating the worm shaft on the slack adjuster. All slack adjuster have a worm and a gear contained in a body having a lever arm. The gear is splined to fit the brake cam shaft. In normal braking, the entire slack adjuster moves as one solid unit. It acts as a simple lever to transmit brake chamber forces to the brake cam shaft as the brakes are applied. All adjustments are made by turning the worm shaft. This turn the worm gear and brake cam shaft and moves the brake shoes either closer to or farther from the brake drum.
Few of the prior art found in few patent application is discussed below with an intention to explain the manner of improvement carried out/attempted by others.
US PATENT NO. 4890540:
In the above patent discloses emergency brake actuator comprises a plurality of breather holes or openings are provided in the housing section of the of the emergency brake actuator chamber that emergency actuator spring to maintain the chamber at atmospheric pressure. One of those openings will be located in the upper hemisphere of the chamber housing and another opening will be located in the lower hemisphere of the chamber housing. A flow resistant plug member, adapted to fit into any of the openings, this arrangement minimizes the amount of dust and dirt particles that enter the chamber and, thus, keeps the chamber free of contamination that could hinder actuator performance.
US PATENT 6006651:
In the above patent discloses about spring brake actuator with filtered service vent openings comprises one or more vent openings. Each opening is covered by one or more filter assemblies. This structure effectively requires all of the air entering and exiting the chamber to go through a filter assembly, while simultaneously protecting the openings and second chamber from dirt, debhs, ice accumulation, paint, salt, and like. The filter assembly comprises a frame and a cover plate with a filter element retained there between. One of those filter assembly is mounted on the

vent opening in the housing section. Another one of those filter assembly is mounted adjacent the exterior side of the central opening to prevent air and contaminants from entering through the central opening.
US PATENT 4889037:
In this above patent discloses about the breather chamber comprises a breather opening to minimize an entrance of contaminated air into an ambient pressure chamber. Behind the entry area of the air entry breather opening chamber along the wall of a housing includes a bell shaped mouth. The unwanted solid type particle has deposited in the housing. Even with normal cleaning can remove the particles.
US PATENT 3800668:
In the above patent discloses about a breathing and failure detection system for spring brakes comprises a breather valve construction serves to connect the spring cavity with the control cavity to insure flow of clean air to the spring cavity as the spring is compressed to release a spring brake application. In the operation of such devices has been the accumulation of dirt and moisture within the spring cavity in order to allow flow of outside air to and from the cavity during spring brake application and release.
The typical working of the brake mechanism with the brake chamber is given below. During brake actuation, the compressed air enters the chamber and pressure builds up between pressure plate (1) and diaphragm (2). Due to air pressure, the diaphragm deflects and moves forward and pushes the push rod assembly (3) out. During the fonward movement of diaphragm, it displaces air through holes (4) in the non-pressure plate (5). This is called breathe-out. Refer Fig. 3 illustrating this action.
When the brake is released, the air pressure between diaphragm (2) and pressure plate (1) is released to atmosphere. Hence the diaphragm moves backward to its home position. This creates negative pressure between diaphragm(2) and non-

pressure plate (5) and atmospheric air enters through the holes (4). This is called breathe -in. Refer Fig.4 illustrating this action.
When there is no brake actuation, the holes are open to atmosphere ail the time thus allowing dust, dirt, water to enter inside the chamber and cause detenoration of components.
OBJECTS OF THE INVENTION
The first object is to have a normal breather mechanism which prevents the entry of contaminants into brake chamber. The second object is to have a breather mechanism which will prevent the entry of contaminants selectively which is an improvement over prior art. The third object is to structure the breather mechanism with additional components such that this simple additional component is easy to fit on the conventional brake chamber.
The other object of the invention is to structure the breather mechanism with a simple one way valve which normally remains closed in idle condition thereby preventing unnecessary contaminants entry into the brake chamber.
ILLUSTRATION OF THE INVENTION
Figure 1 illustrates a typical brake chamber.
Figure 2 illustrates a conventional brake chamber known in prior art.
Figure 3 illustrates the cross section drawing of the brake chamber.
Figure 4 illustrates the cross section drawing of the brake chamber.
Figure 5 illustrates the incorporation of the valve.
Figure 6 illustrates the positioning of the valve.
Figure 7 illustrates the working of the invention.
Figure 8 illustrates the working of the invention.
DESCRIPTION OF THE INVENTION

In many prior art brake chambers, the chamber is simply open to the outside environment and atmosphere through ports, vents or holes in the chamber housing. Hov^/ever such openings invariably allow dirt, moisture and other unw/anted materials and contaminants from the environments outside the brake chambers to enter into the chamber through the ports.
In the invention, a valve is placed over the vent holes and disposed on the outside of the housing to prevent the contaminants from the entering the brake chamber. This valve does not demand large additional space, components, machining and assembly effort.
A flap type one way valve as shown in Fig. 5 is designed and incorporated in the Non-pressure plate. This valve is made of Neoprene rubber.
One valve is installed at the bottom position with flap outside (atmosphere) and is called breathe-out valve.
Another valve is installed in horizontal position with flap inside (chamber inner side) and is called breathe-out valve. Refer Fig. 6 (rotated axially by 90 degree for better view). The valves however mounted with the different mounting positions on the housing.
(n the invention both the vent holes are not left completely open to the environment but are sealed controllably to prevent contaminants from entering the housing under idle condition.
When the brake is applied, the compressed air enters the chamber and pressure builds up between pressure plate (1) and diaphragm (2). Due to air pressure, the diaphragm deflects and moves forward and pushes the push rod assembly (3) out. Duhng the fonward movement of diaphragm (2), the trapped air is pushed out and it escapes by deflecting the flap (6) of the breathe-out valve outwardly. This is called breathe-out. Refer Fig. 7 illustrating this action.

When the brake is released, the air pressure between diaphragm (2) and pressure plate (1) is released to atmosphere. Due to return spring (7) force, the diaphragm moves backward to its home position. This creates negative pressure between diaphragm and non-pressure plate and atmospheric air enters by deflecting the flap of the breathe-in valve. This is called breathe -in. Refer Fig.8 illustrating this action.
When there is no brake actuation, both breathe-In and breathe-out valves are in closed condition (flaps seated). Due to this, free entry of dust, dirt and water in to the chamber is eliminated and hence better life of brake chamber inner components like spring (7), diaphragm (2), push rod (3) and push plate (8).
The invention discloses the breeding system comprising a hole with a control valve, so that the fluid communication is selectively made between the brake chamber and the exterior thereby preventing the entry of contaminants. The patent discloses a pair of breather holes provided on the housing of the chamber. One of the breather hole is located in the lower hemisphere of the housing and the second hole is approximately at 90° with respect to the location of the first hole. A valve is provided in each of the two holes to guide the flow of air Into and away from the brake chamber. Both valves close to seal the brake chamber in Idle condition. This valve is a simple additional part of the breathing system which is performing specifically to overcome a critical problem existing in the prior art. The valves being a one way valve does not allow reverse flow, which is not providing a reverse path.
In view of one or more of the foregoing problems in the current breather holes disposed on the brake chamber, the present invention provides a novel Improved actuator which is simple, reliable, cheap and easy to assemble and service.
Reasonable variations and modifications are possible within the scope of foregoing disclosure without departing from the spirit of the Invention which is described in the specification, illustrated in the drawings and defined In the claims.

WE CLAIM:
1. A diaphragm actuated brake chamber converting energy of air pressure into
mechanical force, with a diaphragm disposed and held between a pressure plate
and a non-pressure plate, a first side of a brake chamber diaphragm exposed to
an applying air pressure and a second side of a brake chamber diaphragm
exposed to atmospheric pressure thereby forming a pressure side and a non-
pressure side of the chamber, and the non-pressure plate vented to the
atmosphere with breathing holes comprising of:
a breath-in hole
a breath-out hole, and
one way valve which so cooperates with the said holes and disposed
on each of the breath-in hole and breath-out hole and positioned on
the housing of the brake chamber.
2. A diaphragm actuated brake chamber converting energy of air pressure into
mechanical force, with a diaphragm disposed and held between a pressure plate
and a non-pressure plate, a first side of a brake chamber diaphragm exposed to
an applying air pressure and a second side of a brake chamber diaphragm
exposed to atmospheric pressure thereby forming a pressure side and a non-
pressure side of the chamber, and the non-pressure plate vented to the
atmosphere with breathing holes comprising of;
a breath-in hole
a breath-out hole and characterized in each hole encompassed with a
pressure sensitive one way valve
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3. A diaphragm actuated brake chamber converting energy of air pressure into
mechanical force, with a diaphragm disposed and held between a pressure plate
and a non-pressure plate, a first side of a brake chamber diaphragm exposed to
an applying air pressure and a second side of a brake chamber diaphragm
exposed to atmospheric pressure thereby forming a pressure side and a non-
pressure side of the chamber, and the non-pressure plate vented to the
atmosphere with breathing holes comprising of:
a breath-in hole
a breath-out hole characterized in each hole encompassed with a one
way flap type valve
4. A diaphragm actuated brake chamber as claimed in claim 1, wherein the one way valve is made of neoprene rubber.
5. A diaphragm actuated brake chamber as claimed in claim 1, wherein the breath-out valve is generally mounted at the bottom position In the brake chamber.
6. A diaphragm actuated brake chamber as claimed in claim 1, wherein the breath-in valve is generally mounted at the horizontal position in the brake chamber.
7. A diaphragm actuated brake chamber as claimed in claim 1, wherein the breath-out valve has the flap disposed outwardly to atmosphere.
8. A diaphragm actuated brake chamber as claimed in claim 1, wherein the breath-in valve has the flap disposed inwardly within the chamber.
9. A diaphragm actuated brake chamber as claimed in claim 1, wherein the flap is substantially encompassed on and covering the vent hole.
10. A diaphragm actuated brake chamber as claimed in claim 1, wherein the flap is a flexible flap adapted to selectively open the vent hole under the action of pressurized air.

11. A diaphragm actuated brake chamber as claimed in claim 1, wherein the breath-in and breath-out holes are apart from one another.
12. A diaphragm actuated brake chamber as claimed in claim 1, wherein the breath-in and breath-out holes are disposed 90° apart from one another.
13. A diaphragm actuated brake chamber as claimed in claim 1, the one way valve comprises:

(a) a flat cylindrical valve body having a top surface and bottom surface and with a radial hole extending from a central axial hole.
(b) a flat cylindrical valve seat disposed at bottom surface of the valve body, said seat also having a central axial opening hole corresponding and matching the central axial hole of the valve body, the said central axial opening further extending on either side to form two radially extending paths each terminating on a hole at either side, and
(c) a flat flexible plate type pressure sensitive movable flap disposed on the top surface of the valve body.
14.A diaphragm actuated brake chamber as claimed in claim 1, wherein the diameter of valve body is less than the diameter of the valve seat.
15.A diaphragm actuated brake chamber as claimed in claim 1, wherein the valve is made of unitary component.
16. A method for bleeding air from a brake chamber comprising the steps of
(a) sealing the breath-in hole and the breath-out hole each with a valve in idle state when there is no brake actuation and
(b) opening the said two holes by actuating the said corresponding valves when there Is a brake actuation, to convey air through the said holes.
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17. A method for bleeding air from the brake chamber wherein the valves of claim 16
is a pressure sensitive one way valve.
18. A method for bleeding air from the brake chamber wherein the valves of claim 16
is a one way flap type valve.