Air Brake System with Anti-Compounding Hand Brake Valve
Field of the invention
The present invention pertains generally to an anti-compounding system for vehicles. and; more particularly, to an anti-compounding mechanism in a hand brake valve of the vehicle as a single unit.
Background of the invention
Compounding is the combination of two forces that is force applied by a spring brake also known as parking brake and the force applied by a service brake. The parking brake should be in the released position before making the service brake application. A full brake application is made when the parking brake is applied that can compound the force exerted on slack adjusters and linkage which in turn could result in damage or brake failure.
Conventionally, anti compounding valves are being used in an air brake system in large commercial vehicles. These anti compounding valves help to balance the pressure applied to the slack adjuster by simultaneously applying air to the spring brake relay when the service brake is pushed. The air is applied to the parking brake chamber as air pressure is applied to the service brake chamber thus releasing the parking brake by the same amount that the service brake is applied thus balancing the pressure in the brake chamber. This prevents excessive pressure from being applied to the service side and subsequently to the rod and slack adjuster.
Currently, addition of an anti-compounding feature in the air brake system is done by adding one more valve between a hand brake valve (HBV) and a spring brake actuator (SBA). The anti-compounding feature takes the signal from HBV and a Foot

Brake Valve (FBV) whichever is higher and delivers outlet pressure to the spring brake side in order to perform anti-compounding function. This increases the complexity as well as cost of the brake system.
Prior Art:
Anti-Compounding Relay Valve: This relay valve is used in the air brake system between HBV and SBA. This relay valve gets the signal from HBV and FBV simultaneously. The relay valve's supply side is connected to an auxiliary tank of the vehicle and delivery is connected to the spring brake side of the SBA. There is no direct connection between HBV or FBV signal to the spring brake side of the SBA but only signal is given to Anti-compounding Relay Valve (ACRV), through which delivery is made to the SBA depending on the amount of pressure signal received from the HBV or the FBV. When the vehicle is in parking mode, the HBV is applied i.e. all air from delivery side of HBV is exhausted which in turns exhaust all air from spring brake side through anti-compounding relay valve (ACRV) and the parking brake is applied due to release of spring brake. No service brake is applied.
Now the HBV is in applied condition and when the service brake is applied through the FBV, one signal goes to service side of the SBA applying service brake. At the same time another signal goes to the ACRV, which takes over the charge of the valve and delivers same amount of pressure as that of FBV to spring brake side of the SBA. This releases spring brake and prevents 'compounding' of the brake.
However, the above-mentioned anti-compounding feature requires an additional valve that is the relay valve which makes the braking system more complicated and expensive.
Anti-compounding using double check valve: Anti-compounding in the vehicle is also achieved through a double check valve. The placement of double check valve

(DCV) is same as of ACRV that is between the HBV and the SBA. However, the main difference between the DCV and the ACRV is that, the HBV and the FBV is directly connected to the spring brake side of the SBA through the DCV unlike the ACRV. However, addition of one more valve in a system to achieve anti-compounding, feature makes the system robust, more leakage prone and expensive.
Inversion Valve with Anti-compounding protection: This is the combination of inversion relay valve and anti-compounding valve. Functionality of anti-compounding protection with the inversion valve is same as that of anti-compounding relay valve described earlier. Accordingly, in order to use the anti-compounding valve, whole inversion unit needs to be included in the brake system. This makes the system costly as well as complicated.
Accordingly, there exist a need to provide an anti-compounding feature in a vehicle that overcomes drawbacks of the prior art.
Objects of the present invention
An object of the present invention is to provide an anti-compounding hand brake valve that reduces requirement of addition of an extra valve in a braking system.
Another object of the present invention is to provide an anti-compounding hand brake valve for vehicles that is capable of being fitted on any vehicle having fluid (gas or liquid) operated braking system.
Yet another object of the present invention is to provide an anti-compounding hand brake valve for vehicles that is capable of being retrofitted on existing vehicles with minor vehicle modifications.

Still another object of the present invention is to provide an anti-compounding hand brake valve for vehicles that is capable of preventing simultaneous application of a parking brake and a service brake in the event of application of the hand brake valve and a foot brake valve simultaneously.
Yet another object of the present invention is to provide an anti-compounding hand brake valve for vehicles that operates without affecting basic braking system performance and doesn't allow complete brake system failure in case if the anti-compounding hand brake valve itself fails.
Summary of the invention
Accordingly, the present invention provides an air brake system with an anti-compounding hand brake valve. The air brake system comprises a first reservoir of pressurized air, a foot brake valve, a front brake actuator, a second reservoir of pressurized air, a rear brake actuator having a spring brake compartment and a service brake compartment and a third reservoir of pressurized air. The second reservoir of pressurized air operates the front brake actuator. The third reservoir of pressurized air operates the rear brake actuator. The first reservoir of pressurized air operates the anti-compounding hand brake valve. The air brake system is characterized in that the anti-compounding hand brake valve is connected only to the spring brake compartment and comprises a handle/lever, an inlet, an exhaust valve, a signal port and an outlet.
The handle is operable to and from a first position and a second position. The handle is operated in the first position to bring a vehicle in a parking mode. The handle is operated in the second position to bring a vehicle in an operating mode. Typically, the handle is manually operated to and from the first position and the second position.

The inlet is capable of receiving pressurized air from the first reservoir and supplying the pressurized air therefrom in response to the position of the handle. The exhaust port is capable of draining out pressurized air from the spring brake compartment in response to the position of the handle. The signal port is capable of receiving pressurized air from the foot brake valve. The outlet is capable of connecting to any of the inlet and the exhaust port in response to fluid pressure in the signal port.
Brief description of the invention
Figures 1-5 show a schematic diagram of an air brake system with an anti-compounding hand brake valve (HBV) in accordance with the present invention.
Detail description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art. techniques and approaches are overcome by the present invention as described below in the preferred embodiment.
The present invention provides an anti-compounding hand brake valve that effectively and easily supports the functionality of an anti-compounding feature yet overcome limitations of prior art systems. The anti-compounding hand brake valve is capable of being fitted on any vehicle having fluid (gas or liquid) operated braking system. The anti-compounding hand brake valve is capable of being retrofitted on existing vehicles with minor vehicle modifications. The anti-compounding hand brake operates without affecting basic braking system performance and doesn't allow complete brake system failure in case if anti-compounding hand brake itself fails.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.
Referring now to figure 1, there is shown an air brake system (100) (herein after referred as "the system (100)" with an anti-compounding hand brake valve (101) (hereinafter the 'HBV (101):), in accordance with the present invention. The system (100) comprises a foot brake valve (102), a front brake actuator (109), a rear brake actuator (103), at least three reservoirs of pressurized air: a first reservoir (104), a second reservoir (105). and a third reservoir (106). The front brake actuator (109) and the rear brake actuator (103) are operated by pressurized air from the third reservoir (106) and the second reservoir (105) respectively. The rear brake actuator (103) includes a spring brake compartment (107) and a service brake compartment (108). The pressurized air from the first reservoir (104) operates the HBV (101) of the system (100).
The system (100) is characterized in that the HBV (101) is connected to only the spring brake compartment (107) of the rear brake actuator (103). Thus, failure of the HBV (101) does not affect working of front brakes thereby preventing complete failure of the system (100). The HBV (101) includes a handle (101a), an inlet (101b)3 an exhaust port (101c), a signal port (lOld) and an outlet (lOle). The handle (101a) is a manually operated lever used by a driver to park the vehicle. The handle (101a) is operable to and from a first position (1) (refer figures 2-5) and a second position (2) (refer figures 2-5). The handle (101a) in the first position (1) brings the vehicle in a parking mode. The handle (101a) in the second position (2) brings the vehicle in an operating mode. The inlet (101b) is capable of receiving pressurized air from the first reservoir (104) and supplying the pressurized air therefrom in response to the position of the handle (101a). The exhaust port (101c) is capable of draining out pressurized air from the spring brake compartment (107) in response to the position of the handle

(101a). The signal port (lOld) is capable of receiving pressurized air from the foot brake valve (102). The outlet (lOle) is capable of connecting to any of the inlet (101b) and the exhaust port (101c) in response to fluid pressure in the signal port (lOld).
The operation of the handle (10la) from the second position (2) to the first position (1) as shown in figure 2 activates the spring brake compartment (107) that in turn applies the parking brake. At this condition, the outlet (101 e) is connected to the exhaust port (101c) and there is no fluid pressure in the signal port (101 d). The driver shifts the vehicle from the parking mode to the operating mode by operating the handle (101a) from the first position (1) to the second position (2) as shown in figure 2 to disconnect the existing connection between the outlet (101 e) and the exhaust port (101c) and simultaneously connecting the inlet (101b) to the outlet (101e)) thereby connecting the first reservoir (104) fluid pressure to the spring brake compartment (107) of rear brake actuator (103) that in turn releases the parking brake. This is the normal operating behavior of the hand brake valve (101).
Referring again to figure 1, the signal port (lOld) is connected to outlet fluid pressure side of the foot brake valve (102). Now when the handle (101a) is in first position (1) and the foot brake valve (102) is not applied, the signal port (lOld) receives no fluid pressure. The outlet (lOle) gets connected to the exhaust port (101c) as shown in figure 2. The fluid pressure from the spring brake compartment (107) gets drained out through the exhaust port (101c) thereby applying the parking brake. Further, when the vehicle is in parking mode and driver applies the pedal of the foot brake valve (102), depending on the pedal application, certain amount of fluid pressure goes to the service brake compartment (108) of the rear brake actuator (103) that in turn applies the service brakes. Simultaneously, same amount of fluid pressure goes to the signal port (lOld) of the HBV (101). As a result, the outlet (lOle) is disconnected from the exhaust port (101c) and connected to the inlet (101b) to deliver proportionate amount

of fluid pressure in accordance with the signal port (lOld) fluid pressure as shown in figure 3. Concisely, when the parking brake is applied and if the driver applies service brake, the HBV (101) automatically disconnects the parking brake, fully or partially depending on the service brake application and avoids compound braking of the service brake compartment (108) and the spring brake compartment (107).
Further, when the vehicle is in the operating condition, the handle (101a) is at the second position (2) and the inlet (101b) is connected to the outlet (lOle). When the handle (101a) is at this position, the HBV (101) delivers 'X' amount of fluid pressure to the spring brake compartment (107) making the parking brakes inactive by releasing the parking brakes. Now, when driver applies the foot brake valve (102), certain amount of fluid pressure goes to the signal port (lOld). However, unless the signal fluid pressure is equal to or greater than 'X\ the HBV (101) does not sense the signal fluid pressure coming from the foot brake valve (102).
When the driver applies the hand brake partially that is the handle (101a) is at some point between the first position (1) and the second position (2) to deliver certain amount of the fluid pressure from the inlet (101b) to the outlet (lOle), pressure 'P' is obtained. At this condition, the fluid pressure caused by the handle (101a) at the outlet (lOle) is 'P'. Simultaneously, when the driver applies the foot brake valve (102) to deliver certain amount of pressure based on the pedal application to the signal port (lOld) side of the HBV (101), the signal port (lOld) generates proportionate amount of outlet pressure 'Q' in the HBV (101). If the pressure 'Q' generated by the signal pressure coming from the foot brake valve (102) is greater than the pressure 'P' generated by the handle (10la) position then the pressure at the outlet (101 e) changes from fluid pressure 'P' to fluid pressure 'Q'Concisely, the HBV (101) automatically switches over to the higher fluid pressure caused either by the fluid pressure at the signal port (lOld) or by the fluid pressure caused by the

handle (101a) position and delivers that higher fluid pressure to the spring brake compartment (107).
Specifically, following four events determine the functionality of the HBV (101) of the system (100).
1. When the handle (101a) is at the first position (1) and there is no signal fluid pressure at the signal port (lOld), then the outlet (lOle) is connected to the exhaust port (101c) and the inlet (101b) is blocked as shown in figure 2.
2. When the handle (101a) is at the first position (1) and there is certain amount of fluid pressure at the signal port (101d), then the outlet (lOle) is connected to the inlet (101b) and the exhaust port (101c) is blocked as shown in figure 3.
3. When the handle (101a) is at the second position (2) and there is no signal fluid pressure at the signal port (lOld), then the outlet (lOle) is connected to the inlet (101b) and the exhaust port (101c) is blocked as shown in figure 4.
4. When the handle (101a) is at the second position (2) and there is certain amount of fluid pressure at the signal port (101d) then the outlet (lOle) is connected to the inlet (101b) and the exhaust port (101c) is blocked as shown in figure 5.
Advantages of the present invention
1. The system (100) with the HBV (101) is capable of being installed on any basic vehicle without adding any valve or system to achieve anti-compounding feature.
2. The system (100) with the HBV (101) improves reliability due to use of less number of parts.
3. The system (100) with the HBV (101) becomes more cost effective with the use
of the HBV (101) as there is lesser number of parts and piping connections as
compared to the prior arts.

4. The system (100) with the HBV (101) is economical to manufacture.
5. The system (100) with the HBV (101) is capable of being retro fitted on existing field vehicles.
The foregoing object the invention is accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention.

We Claim:
1. An air brake system with an anti-compounding hand brake valve, the air brake system comprising a first reservoir of pressurized air to operate the anti-compounding hand brake valve, a foot brake valve, a front brake actuator, a second reservoir of pressurized air to operate the front brake actuator, a rear brake actuator having a spring brake compartment and a service brake compartment, and a third reservoir of pressurized air to operate the rear brake actuator, the air brake system characterized in that the anti-compounding hand brake valve being connected only to the spring brake compartment, the anti-compounding hand brake valve having:
• a handle/lever being operable to arid from a fist position and a second position;
• an inlet capable of receiving pressurized air from the first reservoir and supplying the pressurized air therefrom in response to the position of the handle;
• an exhaust port capable of draining out pressurized air from the spring brake compartment in response to the position of the handle;
• a signal port capable of receiving pressurized air from the foot brake valve; and
• an outlet capable of connecting to any of the inlet and the exhaust port in response to fluid pressure in the signal port.
2. An air brake system as claimed in claim 1, characterized in that the
handle is operated in the first position to bring a vehicle in a parking mode.
3. An air brake system as claimed in claim 1. characterized in that the handle is operated in the second position to bring a vehicle in an operating mode.
4. An air brake system as claimed in claim 1, characterized in that the handle is

manually operated to and from the first position and the second position.