1. Field of the Invention
The present invention refers to a device for a container which includes a casing defining an inner space and an outlet space, which extends from the inner space and is arranged to be connected to a vacuum source in such a manner that the pressure in the inner space and the outlet space in a state of use is less than the pressure of a surrounding space outside the casing, wherein the device includes a valve arrangement which includes
a first valve seat, which forms a first passage between the inner space and the outlet space,
a first valve element, which is abuttable against the first valve seat for closing the first passage in a first position of the valve arrangement and which is displaceable from the first valve seat to a second position of the valve arrangement for opening the first passage, and
a spindle portion which is connected to the first valve element and extends through the first valve seat, the outlet space and a second passage through the casing.
2. Description of the Prior Art
It is known to use such devices for claws, which includes an outlet pipe connected to a vacuum source and arranged to transport milk from the inner space of the claw to an collecting member of a milking machine. Furthermore, such claws include inlet members, which are arranged to permit the supply of milk from a respective teatcup via a short milk conduit or a teatcup liner. During milking there is a subpressure in the inner space and in the milk conduits. Certain milking machines offer the possibility to detach the teatcups from the teats automatically, wherein the subpressure in the inner space of the claws and the conduits is removed before the detachment takes place. Since the pressure then will be substantially equal in the inner space of the claw and in the surrounding space, the teatcups will fall off the teats. However, many milking machines do not have any such automatic detachment of the teatcups. The low pressure level in the interior of the claw is thus maintained after the milking is terminated. One such known claw, see for instance WO97/27738, includes a closing valve by which a passage between the inner space of the claw and an outlet space in the outlet pipe may be closed in such a way that no milk flow may flow from the inner space of the claw through the long milk conduit any longer. Furthermore, the low pressure level in the inner space of the claw will increase slowly thanks to an air inlet which permits a certain air inflow from the surrounding space to the inner space of the claw.
However, this air inlet has in the first place another purpose, namely to facilitate the removal of the milk from the inner space of the claw to said collecting member, and therefore has very small dimensions, which means that the pressure between the surrounding space and inner space will be equalised very slowly. Due to this slow pressure equalisation it will take a long time before the teatcups may be detached in an easy manner from the teats.
The object of the present invention is to remove the problems mentioned above and to provide a device by which the detachment of the teatcups from the teats may be facilitated. In particular, it is aimed at a device by which the pressure between the surrounding space and the inner space of a container, which in a state of use has a very low pressure, may be equalized when the inner space of the container is closed from the pressure reducing source.
This object is obtained by the device initially defined, which is characterized by means which are arranged to form a flow passage which, in the first position of the valve arrangement, permits a flow from the surrounding space to the inner space. By the provision of such a flow passage the pressure in the inner space of the container and the surrounding space will be equalized in a substantially more quick manner than by the technique known up to now. Advantageously, such means are arranged to prevent a flow through the flow passage in the second position of the valve arrangement. In such a way, the flow passage according to the invention will not give rise to any air inflow to the inner space of the container when the valve arrangement is in the open position. For instance, in the case of a claw it is obtained that no air is leaking into the claw during milking. Furthermore, the flow passage is advantageously formed by a channel, which is closed with regard to the outlet space.
According to an embodiment of the invention, the channel extends through the first valve element and the spindle portion. By positioning the channel in this way, the displacement of the valve arrangement between the first position and the second position may be utilized to open and close, respectively the flow passage. Furthermore, such a positioning of the channel requires a small space, which is advantageous with regard to claws.
According to a further embodiment of the invention, the valve arrangement includes a second valve seat, which surrounds the second passage, and a second valve element, which is arranged to abut the second valve seat in said first position for closing the second passage between the outlet space and the surrounding space and which is displaced from the second valve seat in said second position. By such a second valve element, air is prevented from leaking from the surrounding space into the outlet space when the first valve element is in the closed position. Advantageously, the channel has an orifice in the surrounding space at least when the valve arrangement is in the first position.
According to a further embodiment of the invention, the second valve element extends around the spindle portion. A body of a flexible material may be provided around the spindle portion and form the first valve element and the second valve element. Such a body, for instance of rubber, may in a relatively easy manner be brought to seal against both the first valve seat and the second valve seat. Furthermore, by such a common body for the valve elements the mounting of the valve arrangement is facilitated. Furthermore, the spindle portion may include a groove which extends along the spindle portion and which together with said body forms the channel. Such a groove may be manufactured in a relatively simple manner, wherein the channel is obtained in connection with the mounting of the valve arrangement.
According to a further embodiment of the invention, the spindle portion is connected to a manoeuvre member, which is located in the surrounding space and is arranged to permit manoeuvring of the valve arrangement at least from the first position to the second position. Thereby, the manoeuvring member may be arranged to form a third valve element, which is abuttable against a third valve seat which is located on the outer side of the casing and extends around the second passage, wherein the third valve element is arranged to close the second passage when the valve arrangement is in the second position in order to prevent a flow from the surrounding space to the outlet space. The orifice is preferably located on the spindle portion between the third valve element and the second valve element, i.e. a flow from the surrounding to the inner space is obtained first when the third valve element does not abut the third valve seat.
The invention is applicable to a container in the form of a claw, which is arranged to be connected to a milking machine via a milk conduit and an outlet space, and to a number of teatcups which are connected to the inner space via the inlet members extending through the casing.