| 摘要 |
The invention relates to a filter holder comprising a filter housing having a bottom and a dispensing duct or aperture through said bottom. A valve with a valve stopper is arranged for selectively opening and closing the dispensing duct or aperture, the valve stopper being supported by a pivoting arm and resiliently biased towards a closed position. The valve stopper is closed when the filter holder is attached to a hot-water dispensing unit of a beverage producing machine, so that hot pressurized water will soak a beverage ingredient, for instance coffee powder, loaded in the filter cup. The valve is calibrated so that it will open once a certain pressure in the filter cup has been achieved. Once opened, the valve stopper will remain open irrespective of the pressure inside the filter cup, by means of the arrangement described here below. The filter holder further comprises a cam located between the bottom of the filter housing and the pivoting arm which supports the valve stopper. The cam has a cam profile co-acting with the pivoting arm. The cam is movable, preferably around a pivoting or hinge axis to selectively take different positions. More particularly, the cam has at least a first position wherein the cam profile prevents closing movement of the valve stopper and a second position wherein the cam profile allows closing movement of the valve stopper. The cam is resiliently biased towards the first position by a suitable resilient member, for example a spring, such as a torsion spring. Furthermore, the filter holder comprises a slider which co-acts with the cam to move the cam from the first position towards the second position against the resilient action applied on the cam. The slider is advantageously resiliently biased in an inactive position and is forced to move towards an active position by direct or indirect co-action with an element of a water dispensing unit whereto the filter holder is attached. The slider is configured and arranged so that during said movement from the inactive position to the active position, the slide pushes the cam towards the second position, i.e. the cam position which allows closing of the valve stopper. The resilient force applied on the slider is overcome by the co-action of the slider with the above mentioned stationary element. Once the co-action with the stationary element ceases, the slider is resiliently returned to the inactive position. |
