Flexible dust boot for automotive brake cylinder

A drum brake system comprising:

• a housing for the brake cylinder defining a cylinder bore and at least two first interface seats having at least two first grooves thereon;
• a first actuation member of a linear actuator disposed in the cylinder bore and moveable relative to the housing, wherein the linear actuator defines a second interface seat having a second groove thereon;
• a second actuation member disposed in the cylinder bore and moveable relative to the housing, wherein the linear actuator defines a third interface seat having a third groove thereon wherein the second actuation member acts in an opposing direction from the first actuation member;
• a compression spring member interposed axially between the first and second actuation members so that the first and second actuation members are flexibly spread apart from each other thus safeguarding the nominal hydraulic chamber volume when the brake system remains driveless under brake release condition, whereby the ends of the compression spring member are allocated in opposed blind bores of the first and second actuation members;
• a first flexible dust boot for the first actuation member;
• a second flexible dust boot for the second actuation member;
• a first interface on each of the first and the second boots having an annular shape and which is attachable to the housing at a respective one of the at least first interface seats, and wherein the first interface is located radially outward from the at least two first interface seats;
• a second interface on each of the first and second boots having an annular shape with a different diameter than the first interface, wherein the second interface is attachable to one of the first and the second actuation members at a respective one of the second and third interface seats, wherein the second interface is located radially outward from the second and the third interface seats respectively;
• and
• flexible bellows of the on each of the first and the second boots connecting the first interface and the second interface, such that an internal chamber is at least partially formed when the first interface is secured to the housing and the second interface is mounted to one the of the first and second linear actuators respectively such that the first and the second boots protect against ingress of foreign substance in to a first and a second interior chamber while allowing for relative movement between the housing and the first and second linear actuators;
• and
• at least one pressure relief valve on each of the first and second boots which is at least one flange proximate to at least one of the first interface and the second interface and facing one of the first interface seat and one of the second and third interface seats, wherein the at least one pressure relief valve is normally closed and automatically actuates to an open position when a pressure of the respective first and second interior chamber increases to a predetermined pressure differential than a pressure of an exterior pressure;
• wherein the at least one pressure relief valve integrates relief valve spring elasticity in the respective first and second flexible boot, and wherein the first interface or the second interface of the boot integrates a relief valve body, and a part of the radially grooved counterpart first, second or third seat integrates a relief valve seat of the at least one relief valve and wherein the relief valve seat is the same surface as the radially grooved counterpart first, second or third seat;
• wherein the pressure relief valve body integrates a separate recessed portion, and wherein the recessed portion is fluidly connected with the respective first and second interior chamber and separated from the exterior;
• wherein the recessed portion is a longitudinal slot which is arranged in one of parallel and antiparallel with respect of the linear displacement direction of the respective first and second actuation member;
• wherein the recessed portion is separated from the exterior via an end wall, and wherein the end wall is arranged orthogonally with respect to the linear displacement direction of the respective first and second actuation members.