Title of Invention

AN INVERSION VALVE FOR THE AIR BRAKE SYSTEM OF A MOTOR VEHICLE

Abstract An inversion valve for the air brake system of a motor vehicle comprising a valve body provided with a spring brake control port, a primary service port, a secondary service port, a reservoir port, a delivery port and an exhaust port; the valve body housing a spring-loaded primary piston and relay piston; a diaphragm valve for the spring brake control port and an air chamber provided above the primary piston; a spring-loaded inlet/exhaust valve, the arrangement being such that whenever (1) the inlet/exhaust valve is open, pressurised air enters the reservoir port and leaves a the delivery port until, at a predetermined pressure~ the inlet valve closes under such pressure preventing further passage of air to the delivery port, while maintaining the exhaust port closed (2). The air in the chamber is depleted, by operation of the park control valve of the vehicle, the primary piston, and along with it the relay piston, under the airhead load beneath the relay piston~ move upward~ thereby opening the exhaust port and allowing the air from the delivery port to pass out, through the inlet/exhaust valve and the exhaust port, thus applying the spring brakes (3). When the service brakes are applied, with the spring brakes also applied, the diaphragm valve is deflected by the pressurised air entering the primary service port to seal the spring brake control port and allow such air into the air chamber, causing the primary piston and the relay piston to move downward, to open the inlet/exhaust valve, allowing air to flow from the reservoir port to the delivef)' port, thus releasing the spring brakes (4). Whenever failure of the primary brake circuit occurs, air c ~, entering the secondary service port acts on the relay ,~ piston causing the relay piston to move upwards and thus allowing air from the delivery port to pass through the exhaust, applying the spring brakes (5). When the spring brakes are released and the service brakes are applied, air of substantially the same pressure enters through the primary and secondary service ports on either side of the " relay piston, thus leaving the relay piston unaffected.
Full Text This invention relates to an inversion valve for the air brake system of a motor vehicle.
The known inversion valve along with the double check valve and relay valve is primarily used in truck and tractors equipped with spring brakes.
The known inversion valve enables a predetermined value of hold-off pressure to be maintained, keeping the spring brakes released. The hold-off pressure is usually varied from 4 bar to 7 bar. The said valve enables exhaustion of air from the spring brakes, while parking the vehicle, thereby allowing application of the spring brakes. The said valve prevents compounding of the service brakes and the spring brakes and modulates application of the spring brakes in the event of a failure in the primary service brake circuit.
The inversion valve proposed herein dispenses with the need to utilize the known double check valve, the relay

valve and the known inversion valve as separate devices in the air brake system. On the other hand, the inversion valve proposed herein combines, in itself, the function of the known inversion valve, the double check valve and the relay valve as one integral unit. Thus the proposed inversion valve is compact and occupies less space. Servicing and maintenance is also rendered easier. The known three valves aforesaid of the existing system are also easily replaceable with the inversion valve proposed herein. The number of working parts of the known system, comprising the known inversion valve, the known double check valve and the known relay valve are more than those of the proposed inversion valve. This is because lesser number of components in the proposed inversion valve performs the functions of the known inversion valve, the double check valve and the relay valve put together. Further more in the proposed inversion valve, spring, loading the primary piston and the relay piston (also called the graduating spring), is "caged" that is to say that the entire spring assembly is in a caged condition and allowed to

move along with the relay piston and the primary piston, even as it provides the necessary load to achieve the pressure limiting function. This feature is unlike the known means of employing a graduating spring, wherein one end of the spring is made to rest on a stationary surface.
Various other features of the inversion valve proposed herein will be apparent from the following further description there of given hereunder:
The inversion valve for the air brake system of a motor vehicle comprises a valve body provided with a spring brake control a primary service port, a secondary service port, a reservoir port, a delivery port and an exhaust port; the valve body housing a spring-loaded primary piston and relay piston; a diaphragm valve for the spring brake control port and an air chamber provided above the primary" piston; a spring-loaded inlet/exhaust, valve the arrangement being such that whenever (I)the

Inlet exhaust valve is open, pressurised air enters the reservoir port and leaves at the delivery port until, at a predetermined pressure, the inlet valve closes under such pressure preventing further passage of air to the delivery port, while maintaining the exhaust port closed (2). The air in the chamber is depleted, by operation of the park control valve of the vehicle, the primary piston, and along with it the relay piston, under the airhead load beneath the relay piston, move upward, thereby opening the exhaust port and allowing the air from the delivery port to pass out, through the inlet exhaust valve and the exhaust port, thus applying the spring brakes (3). When the service brakes are applied, with the spring brakes also applied, the diaphragm valve is deflected by the pressurised air entering the primary service port to seal the spring brake control port and allow such air into the air chamber, causing the primary piston and the relay piston to move downward, to open the inlet/exhaust valve, allowing air to flow from the reservoir port to the delivery port, thus releasing the spring brakes (4). Whenever failure of the primary- brake circuit occurs, air

entering the secondary" service port acts on the relay piston causing the relay piston to move upwards and thus allowing air from the deliver," port to pass through the exhaust. applying the spring brakes (5). When the spring brakes are released and the service brakes are applied, air of substantially the same pressure enters through the primary and secondary- service ports on either side of the relay piston, thus leaving the relay piston unaffected.
This invention will now be described with reference to the accompanying drawings, which illustrate by way of example, and not by way of hmitation. one of several possible embodiments of the inversion valve proposed herein.
Figure 1- illustrating sectional view" of the said embodiment with the spring brakes releasing
Figure 2- illustrating sectional view of the said embodiment in spring brakes released-balanced condition.
Figure 3- illustrating sectional view of the said embodiment with the spring brakes applied

Figure 4- illustrating sectional view of the said embodiment with the service brakes applied with spring brakes applied.(Anti-compounding)
Figure 5- illustrating sectional view of the said embodiment when service brakes are applied with the primarv- brakes in failed condition.
Spring brakes released
When the system is being charged, air pressure enters the reservoir port (B) and is present in the cavity beneath the inlet exhaust valve (6). The inlet/exhaust is in contact with the inlet valve seat in the body (1) thus preventing passage of air to deliver as well as through the exhaust. When the full system pressure is reached, the "park control valve" can be operated to release the spring brakes. The park control valve is a manually operated on/off valve. Shifting the park control valve to the "on" condition ensures continuous supply of air pressure at the spring brake control port (A) of the inversion valve. Pressurised air at the spring brake control port (A), deflects the diaphragm (2), and flows

into the cavity on top of the primary " piston (3) through
the cross-hole (H) provided in the valve body (1). This
air pressure forces the primary piston (3). to move
downward and contact the relay
downward and contacts the inlet/exhaust valve (6).
Further movement of the relay piston (5) opens the inlet
passage thereby allowing air to flow from the reservoir
port (B) to the delivery ports (C).Consequently the spring
brakes are released. At the same time the exhaust valve
seat in the relay piston (5) prevents loss of air through
exhaust. The valve in this mode of operation is
illustrated in figure 1.
The limiting value of the hold-off pressure (or pressure at the delivery ports) to the spring brakes can be varied between 4 bar and 7 bar by changing the graduating spring (4) load on the relay piston (5) with the help of the adjustment screw (7). The air pressure that is communicated to the delivery ports (C) also acts on the underside of the relay piston (5). When the airhead load on the relay piston (5) equals the load exerted by the graduating spring (4), the valve is in the "balanced" condition. In this condition the inlet valve seat and the

exhaust valve seat are in the same plane thereby preventing further flow of air to delivery ports ( C) and at the same time preventing loss of air through exhaust. This condition is illustrated in figure 2.
Springs brakes applied
The park control valve is switched to the "off position to apply the parking brakes. Consequently, air pressure at the spring brake control part (A) and on top of the primary piston (3) is exhausted through the park control valve. The primary piston (3) then moves upward. Airhead load beneath the relay piston forces it to move upward thereby opening the exhaust passage and sealing the inlet. Air from the delivery ports (C) is then exhausted thereby applying the spring brakes. This condition is illustrated in figure.3.
Service brakes applied with parking brakes applied (Anti-compounding)
Application of service brakes provides air pressure at the primary service port (PI) and secondary service port

(P2). There is no air pressure in the spring brake control port (A) since the spring brakes are applied. Air entering the primary service port (PI) deflects the diaphragm (2) in the double check valve and seals the passage in the spring brake control port (A). Air then flows through the cross hole (H) provided in the body (1) to the top of the primary piston. This air pressure forces the primary piston (3) to move downward and contacts the relay piston (5). The relay piston (5) then moves downward and contacts the inlet/exhaust valve (6). Further movement of the relay piston (5) opens the inlet passage thereby allowing air to flow from the reservoir port to the delivery ports (C). Consequently the spring brakes are released thereby preventing the compounding of the service brake and the parking brake. This condition is illustrated in figure 4.Continuous application of the service brakes results in the "balanced" condition explained earlier.
Air that enters the valve body through the primary ser\"ice ports (PI) and secondary ser\"ice port (P2) gets

neutralised since the pressure and sealing areas on the top and bottom of the relay piston (5) are essentially equal.
Application of service brakes with primary in failed condition (Modulated application)
In the event of failure in the primary circuit, air pressure, upon application of service brakes will be available only in the secondary service port (P2). However, air pressure will be available at the spring brake control port (A) and consequently the delivery ports (C) thereby keeping the spring brakes released. Air that enters the valve through the secondary service port (P2) acts beneath the relay piston (5) and forces the relay piston to move upward thereby exhausting air from the deliver . ports (C) and applying the spring brakes. The air released from the spring brakes will be proportional to the pressure at secondary" .senice port (P2) thus providing the driver with a modulated application of the spring brakes. This condition is illustrated in figure 5.
Service brakes applied with spring brakes released
During normal running of the vehicle spring brakes are in

the released condition. Service brake application made will result in air pressure entering the valve through the primary service port (PI) and secondary service port (P2). However, this will not have any impact on the functioning of the valve since the pressure and sealing areas on the top and bottom of the relay piston (5) are essentially equal.
Pressure limiting is achieved by caging the spring
Limitation of hold- off pressure to the spring brakes is achieved by caging the graduating spring (4) in the relay piston (5) and primary piston (3). Normally in such applications one end of the graduating spring is always made to rest on a stationary surface In SCL"s valve the unique feature is that the entire spring assembly is in a caged condition and allowed to move along with the relay piston even as it provides the necessary load to achieve the pressure-limiting function.
The terms and expressions in this specification are of description and not of limitation, since they do not exclude any equivalents of the features illustrated and described, but it is understood that various other embodiments of the inversion valve proposed herein are possible without departing from the scope and ambit of the invention.





WEclaim:
1. An inversion valve for the air brake system of a motor vehicle comprising a valve body provided with a spring brake control/ a "primary service port, a secondary service port, a reservoir port, a delivery port and an exhaust port; the valve body housing a spring-loaded primary piston and relay piston; a diaphragm valve for the spring brake control port and an air chamber provided above the primary piston; a spring-loaded inlet’ exhaust valve, the arrangement being such that whenever (1) the inlet exhaust valve is open, pressurised air enters the reservoir port and leaves at the delivery port until, at a predetermined pressure, the inlet valve closes under such pressure preventing further passage of air to the delivery port while maintaining the exhaust port closed (2) The air in the chamber is depleted, by operation of the park control valve of the vehicle, the primary piston, and along with it the relay piston, under the airhead load beneath the relay piston, move upward, thereby opening the exhaust port and allowing the air from the delivery" port to pass out, through the inlet’ exhaust valve and the exhaust port, thus applying the spring

brakes (3) When the service brakes are applied, with the spring brakes also applied, the diaphragm valve is deflected by the pressurised air entering the primary service port to seal the spring brake control port and allow such air into the/ chamber, causing the primary" piston and the relay piston to move downward, to open the inlet’ exhaust valve, allowing air to tow from the reservoir port to the deliver*" port, thus releasing the spring brakes (4) Whenever failure of the primary" brake circuit occurs, air entering the secondary service port acts on the relay piston causing the relay piston to move upwards and thus allowing air from the delivery port to pass through the exhaust, applying the spring brakes (5) When the spring brakes are released and the service brakes are applied, air of substantially" the same pressure enters through the primary and secondary service ports on either side of the relay piston, thus leafing the relay piston unattached,
2. An inversion valve as claimed in Claim I where in the spring, loading the primary"" piston and the relay piston, is adjustable to vary the spring load.

3. An inversion valve as claimed in Claim 2 where in a
screw is provided to vary the spring load.
4. All inversion valve as claimed in any one of the
preceding Claims where in the diaphragm valve
comprises a duct opening out from the spring brake
control port into chamber.
5. An inversion valve as claimed in any one of the
preceding Claims where in the spring, loading the
primary" piston and the relay piston, is cased.
6. An inversion valve for the air brake system of a motor
vehicle substantially as herein described and illustrated
with reference to the accompanying drawings.

Documents:

0857-mas-2001 abstract-duplicate.pdf

0857-mas-2001 abstract.pdf

0857-mas-2001 claims-duplicate.pdf

0857-mas-2001 claims.pdf

0857-mas-2001 correspondence-others.pdf

0857-mas-2001 correspondence-po.pdf

0857-mas-2001 description (complete)-duplicate.pdf

0857-mas-2001 description (complete).pdf

0857-mas-2001 drawings-duplicate.pdf

0857-mas-2001 drawings.pdf

0857-mas-2001 form-1.pdf

0857-mas-2001 form-13.pdf

0857-mas-2001 form-19.pdf

0857-mas-2001 form-26.pdf

0857-mas-2001 form-6.pdf


Patent Number 208704
Indian Patent Application Number 857/MAS/2001
PG Journal Number 35/2007
Publication Date 31-Aug-2007
Grant Date 07-Aug-2007
Date of Filing 18-Oct-2001
Name of Patentee SUNDARAM CLAYTON LIMITED
Applicant Address PADI,CHENNAI 600 050.
Inventors:
# Inventor's Name Inventor's Address
1 SUNDARAMAHALINGAM SELVAMANI PADI,CHENNAI 600 050.
PCT International Classification Number B 60 T 1/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA