Title of Invention

AN AIR CYLINDER FOR THE EXHAUST BRAKE SYSTEM OF AN AUTOMOBILE

Abstract

An air cylinder for IIMJP the exhaust brake system of an automobile, having a compressed-air inlet end and a breathing-air outlet end, comprising a spring-loaded piston reciprocably disposed within the cylinder, the joint between the spring seat and cylinder wall at the said breathing-air outlet end being sealed; an air-inlet port at the compressed-air inlet end; at least one breather hole, at the said breathing-air outlet end, said breather hole being provided with a f^st valve member for allowing breathing-air outflow from the cylinder to atmosphere, during forward movement of the piston, said first valve member, preventing breathing-air inflow, from atmosphere, through the breather hole, into the cylinder; and a second valve member located at the compressed-air inlet port for allowing breathing-air inflow, from atmosphere through the compressed-air inlet port, into the spring side of the cylinder, during the return movement of the piston, said breathing-air inflow, to the spring side of the cylinder, taking place through a cross-hole provided in the piston-rod, said second valve member preventing air outflow from the cylinder to atmosphere.

Full Text

This invention relates to an air cylinder for the exhinst brake system of an automobile for actuation of the butterfly valve. Air pressure is supplied to the air cylinder durmg exhaust brake application. This pressure is converted into mechanical force and this force is used for closing the butterfly valve. The piston rod assembly, within the cylmder» after forward movement of the piston, is returned to its origmal position, with the help of the return spring provided in the air cylinder. The known air cylmder has breather holes Which enable air witbin the cylinder to escape to atmosphere during forward movement of the piston and which also enable air from atmosphere to enter the cylinder durmg the return movement of the piston. These breather holes thus help ffl neutralising the positive pressure build-up caused by the forward movement of the piston and the negative pressure (vacuum pressure) build-up durmg the return movement of the piston, by providmg a route for the egress and ingress of ahr in the cylmder. In the known air cylinder, while air outflow from cylinder to atmosphere takes place, through the breather holes, during forward movement of the piston, air mflow from atmosphere into the cylinder also takes place, through the breather holes, during return movement of the piston. Such air inflow, through the breather holes, is undesirable since it carries with it dust and slush from the road into the cylinder through the breather holes, especially since the air cylinder is installed very close to ground level. Dust and slush entering the cylinder lead to corrosion of the internal components of the ah* cylinder and reduces its efiiciency and operational life. This invention therefore proposes an air cylinder, which eliminates or at least greatly minimises the aforementioned drawbacks of the known air cylinder. Various features of ik'u mvention will be apparent from the following description thereof given hereunder. Accordmg to this invention, the air cylmder for use m the exhaust brake system of an automobile, having a compressed-air inlet end and a breathing-air outlet end, comprises a sprmg-loaded piston reciprocably disposed within the cylinder, the joint between the spring seat and cylinder wall at the said breathing-air outlet end being sealed; an air-inlet port at the compressed-air inlet end; at least one breather hole, at the said breathing-ak outlet end, said breather hole being provided with a first valve member for allowing breathing-air outflow from the cylinder to atmosphere, during forward movement of the piston, said first valve member, preventmg breathmg-air inflow, from atmosphere, through the breather hole, into the cylinder; and a second valve member located at the compressed-air inlet port for allowing breathing-air inflow, from atmosphere through the compressed-air mlet port, into the spring side of the cylinder, during the return movement of the piston, said breathing-air inflow, to the spring side of the cylinder, taking place through a cross-hole provided in the piston-fvd, said second valve member preventing air outflow from the cylinder to atmosphere. This invention will now be described with reference to the accompanying drawings which illustrate by way of example, and not by way of limitation, one of the various possible embodiments of this invention, wherein Fig.l ilhistrates the embodiment m sectional elevation Fig.2 illustrates the air-outlet side of the said embodhnent Fig.3 ilhistrates the air-inlet side of the said embodiment The air cylmder C has a compressed-air inlet end A and a breathing-air outlet end B, and comprises a spring- loaded piston P reciprocably digposed within the cylinder. The spring loading the piston is mdicated by SI. t The jomt between the spring seat G and cylinder wall H at the breathing-ab outlet end B is sealed by an 0-ring R. The air-inlet port at the compressed-air mlet end A is indicated by D. Breather holes E» are located at the breathing-air ontlet end B, said breather holes bemg provided with a first valve member for allowmg breathmg-air ootflow from the cylinder, through the breather holes, to atmosphere during forward movement of the piston, indicated by the arroiiybut preventing breathing-air inflow, from atmosphere, through the breather hole, into the cylinder durmg return movement of the piston mdicated by the arrow Z. In one of its forms, the said valve member comprises a flexible wiper seal F. The wiper seal covers the breather holes E. The wiper seal allows air from within the cylmder to flow out, indicated by the arrow W, of the cylmder to atmosphere, daring forward movement of the piston, but prevents air from atmosphere flowing into the cylmder, through the breather holes, during return movement of the piston. The breath mg-air flow direction > marked X. A second valve member is located at the compressed-air inlet port D for allowing breathing-air mflow, daring retnm movement of the piston, from atmosphere mto the spring side K of the cylinder. This air flow »me compressed-air inlet port to the spring side K of the cylinder takes place through a cross-hole L provided in the piston rod. The said second valve member, however, prevents air-outflow from the cylinder to atmosphere. One of the forms the second valve member mi^ take is a spring-loaded flexible seal M provided for the compressed-air inlet port The spring is indicated by S2. Daring return movement of the piston, it presses against * the seal M to flex it. causing the end portion of thef seal to open, thus allowing breathmg-air inflow from atmosphere to enter the cylinder. The seal M resumes its normal position under the influence of the spring S2. The air passes on to the spring side K of the cylinder through the cross-hole L provided in the piston rod. Thus, the positive pressure build-up on the sprmg aide K of the cylmder daring forward movement of the piston is relieved by air out-flow through the breather holes E. but air-inflow into the cylinder, through the breather holes, is prevented by the first valve member; and the negative pressure (vacuum pressure) build-up on the other side of the cy linden during return movement of the piston, is relieved by air in-flow through the compressed-air mlet port D, but air outflow through the air-inlet port D is prevented by the second valve member, to maintain pressure equilibrium within the cylinder. The terms and expressions in this specification are of description and not of limitation as these do not exchide any equivalent^f the features illustrated and described, but various other embodiments of the air cylinder proposed herein are possible without departing from the scope and ambit of this invention. We Claim: l.An air cylinder for use in the exhaust brake system of an automobile, having a compressed-air inlet end and a breathing-air outlet end, comprising a spring-loaded piston reciprooably disposed within the cylinder, the joint between the spring seat and cylinder wall at the said breathing-air outlet end being sealed; an air-inlet port at the compressed-air inlet end; at least one breather hole, at the said breathing-air outlet end, said breather hole being provided with a first valve member for allowing t uthing-air outflow from the cylinder to ilmosphdt, ing forward movement of the piston, said fn^ valve nber, preventing breathing-air inflow, from atmosphere, through the breather hole, into die cylmder; and a second valve member located at the compressed-air mlet port for allowing breathing-air inflow, from atmosphere through the compressed-an- mlet port, into the spring side of the cylmder, durmg. the return movement of tiie piston, said breathmg-air mflow, to the spring side of the cylinder, taking place through a cross-hole provided in the piston-rod, said second valve member preventing air outflow from the cylinder to atmosphere. 2. An air-cylinder as claimed in Claim 1 wherein an 0- ring is located in the joint between the spring seat and cylinder wall to seal Uie said joint. 3. An air-cylinder as claimed in Chiim 1 or Claim 2 wherein the first valve member comprises a flexile wiper seal of rubber for covering the breather hole or holes, said w^er seal allowing air-outflow from the cylinder to atmosphere, during forward movement of the piston, but preventing air-inflow, through the breather hole, from atmosphere mto the cylmdor, during return movement of the piston. 4. An air-cylinder as claimed in any one of the preceding Claims wherem the second valve member is a spring- loaded flexible seal provided for the compressed-air inlet port. 5. An air cylinder for use m the exhaust brake system of an automobile substantially as herem described and ilhistrated.

Documents:

860-che-2003-abstract.pdf

860-che-2003-claims duplicate.pdf

860-che-2003-claims original.pdf

860-che-2003-correspondence others.pdf

860-che-2003-correspondence po.pdf

860-che-2003-description complete duplicate.pdf

860-che-2003-description complete original.pdf

860-che-2003-drawings.pdf

860-che-2003-form 1.pdf