Cap for a pressure tank, and pressure tank for a gas-powered vehicle
A boss for a pressure tank for storing gas in a gas-powered vehicle. The boss is configured for attachment to a wall of the pressure tank enclosing a cavity for storing the gas. The wall has a reinforcement layer made of fiber-reinforced plastic and an inner liner for sealing. The boss has an external thread, which can be connected to a mating internal thread of the liner. There is also described a pressure tank with two such bosses.
1 . A boss for a pressure tank for storing gas in a gas-operated vehicle, wherein the pressure tank has a wall that encloses a cavity for storing the gas, and the wall includes a reinforcement layer composed of fiber-reinforced plastic and an inner liner for sealing the pressure tank;
the boss comprising:
an external thread for attachment to the wall of the pressure tank, said external thread being configured for meshing with a matching internal thread of the liner and to be arranged concentrically in relation to a longitudinal axis of the pressure tank; and
an annular sealing surface situated on an end face of the boss, arranged perpendicularly to the longitudinal axis or enclosing an angle of between 70° and 110° with the longitudinal axis, said sealing surface configured for the liner to be pushed thereagainst by a spring element to form a throttle point and provide a sealing action; and
a screw thread being an internal thread for receiving a sleeve to be screwed in, the sleeve serving to allow the liner to be pushed against the sealing surface of the boss with the aid of the spring element.
2 . The boss according to claim 1 , wherein said external thread has at least 4 to at most 10 thread turns.
3 . The boss according to claim 1 , wherein said external thread has one end formed with at least one half thread turn with a thread elevation which is smaller than remaining thread elevations, and another end formed with at least one half thread turn with a thread depression which is smaller than remaining thread depressions.
4 . The boss according to claim 1 , wherein the boss is formed with a neck region to be received in a holder, said neck region having a length which is at least 50% of an outer diameter measured at a thinnest point of said neck region.
5 . The boss according to claim 4 , wherein said neck region length is between 40 mm and 80 mm, and said neck region includes a cylindrical outer contour within said neck region length.
6 . The boss according to claim 1 , wherein said external thread is a cylindrical thread, and a diameter of the external thread based on tips of the thread elevations is at least 60 mm and at most 180 mm.
7 . The boss according to claim 6 , wherein the diameter of the external thread is between 90 mm and 180 mm.
8 . The boss according to claim 1 , wherein the annular sealing surface encloses an angle of between 70° and 110° with the longitudinal axis.
9 . The boss according to claim 1 , wherein the external thread is radially further away from the longitudinal axis than the sealing surface to keep a torque load away from the sealing surface situated further inward.
10 . The boss according to claim 1 , wherein said sealing surface includes annular elevations configured to be pushed into the liner.
11 . The boss according to claim 10 , wherein each annular elevation is a few tenths of a millimeter in height.
12 . A pressure tank for storing gas in a gas-operated vehicle, the pressure tank comprising:
a wall defining a circularly symmetrical elongate form which is cylindrical in a central region and is terminated at both ends by domed end caps;
said wall enclosing a cavity for storing the gas, and said wall being formed of a reinforcement layer composed of fiber-reinforced plastic and an inner liner for sealing the cavity;
each of said domed end caps having a metallic connection piece, being a boss;
each boss including:
an external thread for attachment to the wall of the pressure tank, said external thread being configured for meshing with a matching internal thread of said liner and to be arranged concentrically in relation to a longitudinal axis of the pressure tank;
an annular sealing surface situated on an end face of the boss outside said liner and configured for said liner to be pushed thereagainst to form a throttle point and provide a sealing action; and
a spring element associated with each boss, said liner being pushed against said sealing surface of a respective boss by an associated spring element.
13 . The pressure tank according to claim 12 , wherein said external thread of said boss at one end being a right-hand thread and said external thread of said boss at an opposite end being a left-hand thread.
14 . The pressure tank according to claim 12 , wherein said internal threads are produced in said liner by cutting.
15 . The pressure tank according to claim 12 , further comprising, for each of said domed end caps, a sleeve connected to a respective boss and a pressure ring, wherein said spring element is supported against said sleeve to push said pressure ring against said liner, to press said liner against said sealing surface of said respective boss.
16 . The pressure tank according to claim 15 , wherein said pressure ring together with said sleeve fully enclose said spring element.
17 . The pressure tank according to claim 15 , wherein said pressure ring is displaceable relative to said sleeve in a direction of a longitudinal axis L of the pressure tank.