| 摘要 |
A filter cartridge has an annular filter element retained within a housing by an end plate. The end plate has a central outlet and a plurality of inlet holes. Mounted on the end plate is an annular valve support which supports an annular valve member disposed between the valve support and the filter cartridge. A coil spring urges the annular filter member against the valve member which, in turn, engages the valve support and urges the valve support against the end plate. The valve support has an inner sleeve portion which seats against the end plate and an outer sleeve portion with holes therethrough. The valve member has an expandable collar portion which normally seals the bypass holes and a skirt portion which normally seals the inlet holes. When the filter is filtering lubricating oil for an internal combustion engine, the skirt is deflected by pressurized lubricating oil and flows around and through the filter element before passing out of the central outlet in the end plate. When the engine is not running, oil in the filter cartridge is blocked from flowing back out of the inlet holes in the mounting plate. If the media of the filter element becomes clogged, then pressure is exerted through the bypass holes in the valve support and applied to the expandable collar of the valve member. The pressure causes the expandable collar of the valve member to expand to uncover the bypass holes. The lubricating oil then flows through the bypass holes and out of the central outlet opening without having to pass through the filter. Preferably, the valve member is made of a low swell silicone material which requires greater pressure to expand at low cold start temperature than at operating temperatures.
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