Vent assemblies

1 . A vent assembly comprising:

an aperture formed in a wall of a reservoir, the reservoir having an internal surface defining a volume of the reservoir and an external surface;

a closure member retained on the external surface of the reservoir, the closure member comprising a first component and a second component, the second component positioned between the first component and the wall of the reservoir, wherein the first component has a modulus of elasticity greater than the second component, wherein the first component and the second component are both part of the same closure member and are secured to each other;

a sealing surface on the first component or the second component, where the sealing surface closes the aperture when the closure member is in an unvented position and the sealing surface does not close the aperture when the closure member is in a vented position;

a closure member retainer configured to retain the closure member on the reservoir;

a cam surface between the closure member and the wall of the reservoir, the cam surface configured to generate a compressive force on the sealing surface when the closure member is moved into the unvented position;

wherein the cam surface is configured to convert rotational movement of the closure member into linear displacement, thereby generating the compressive force on the sealing surface to ensure a secure seal over the aperture when the closure member is in the unvented position, wherein the cam surface is a contoured surface on the closure member that interacts with a corresponding surface on the wall of the reservoir to achieve the linear displacement and sealing effect.

2 . A vent assembly comprising:

an aperture formed in a wall of a reservoir, the reservoir having an internal surface defining a volume of the reservoir and an external surface;

a closure member retained on the external surface of the reservoir, the closure member comprising a first component and a second component, the second component positioned between the first component and the wall of the reservoir, wherein the first component has a modulus of elasticity greater than the second component, wherein the first component and the second component are both part of the same closure member and are secured to each other;

a sealing surface on the first component or the second component, where the sealing surface closes the aperture when the closure member is in an unvented position and the sealing surface does not close the aperture when the closure member is in a vented position;

a closure member retainer configured to retain the closure member on the reservoir;

a cam surface between the closure member and the wall of the reservoir, the cam surface configured to generate a compressive force on the sealing surface when the closure member is moved into the unvented position;

wherein the closure member is configured for rotation about an axis extending through the wall of the reservoir when moving between the vented position and the unvented position;

wherein the vent assembly further comprises a post extending from the wall of the reservoir in a direction parallel to the axis, wherein the closure member is configured for rotation on the post, wherein the closure member retainer is located on the post and configured to retain the closure member on the post when the closure member is in the vented position, and wherein the compressive force is generated between the closure member retainer and the cam surface when the sealing surface is positioned over the aperture,

wherein the closure member retainer comprises a shoulder extending outwardly from the post relative to the axis

wherein the closure member comprises an inner surface facing the post and a top surface facing away from the wall of the reservoir, wherein the inner surface and top surface of the closure member form an edge, and wherein the edge mechanically engages with the shoulder of the closure member retainer when the closure member is in the unvented position,

wherein the vent assembly is configured so that:

0.9

D

⁢

1

≤

D

⁢

V

<

D

⁢

2

⁢

and

⁢

H

⁢

1

<

H

⁢

V

<

1.2

H

⁢

2

,

wherein:

D1 is the outer diameter of the post at its narrowest dimension;

DV is the diameter of the inner surface of the closure member;

D2 is the outer diameter of the closure member retainer as measured closest to the shoulder;

HV is the thickness of the closure member;

H1 is the height of the post, as measured from an aperture surface portion of the cam surface to the point at which the outer diameter of the post begins to increase;

H2 is the height of the post, as measured from the aperture surface portion to the shoulder.