A method and apparatus for dispensing a viscous liquid, using a valve

Abstract

 A method and apparatus for dispensing a viscous liquid using a valve comprising a body having an inlet (2) and an outlet (3) and a valve member (4) movable perpendicularly to the plane of said outlet. According to the invention, as soon as virtually the entire desired quantity of liquid has passed the outlet the valve member is moved to the outlet at a high velocity, so that the last quantity of liquid is pushed through the outlet, and the valve member is suddenly decelerated by a shoulder of the valve striking a valve seat.

Description

[0001] This invention relates to a method and an apparatus for dispensing a viscous liquid, using a valve comprising a body having an inlet and an outlet and a valve member movable perpendicularly to the plane of said outlet.

[0002] In the prior art methods and apparatuses, a desired quantity of liquid is dispensed through an outlet of the valve and, for example, passed into a container. When the desired quantity of liquid has been passed, the valve is closed, whereafter the container is carried off and a new container is supplied for receiving a metered quantity of liquid. As the valve is closed, in particular in the case of viscous liquids, residues will tend to cling to the valve member and to the wall of the outlet. In this way the valve becomes fouled and starts dripping, thereby causing fouling of the container and the base on which it rests. This requires thorough cleaning of the valve, the container and the base. This need is even greater in those cases in which perishable materials are handled. Consequently, in the methods and apparatuses of the prior art, a considerable amount of additional work and, hence, a considerable amount of additional cost are entailed in maintaining adequate standards of cleanliness and hygiene.

[0003] It is an object of the present invention to provide a method and an apparatus for dispensing a viscous liquid which obviate the disadvantages outlined above.

[0004] To this effect, according to the invention, as soon as virtually the entire desired quantity of liquid has passed the outlet the valve member is moved to the outlet at a high velocity, so that the last quantity of liquid is pushed through the outlet, and is suddenly decelerated upon closing the outlet. Accordingly, during this movement, the last quantity of liquid is pushed through the outlet as a compact whole. At the moment when the entire desired quantity has passed the outlet, the valve member is decelerated with a shock or optionally shockwise in a plurality of steps, whereas the liquid continues to advance under the influence of inertia. Indeed, the liquid will be fully released from the valve member. As the desired quantity of of liquid is forced through the outlet as one whole, no liquid will cling to the wall of the outlet.

[0005] Preferably, the liquid is pushed onward in the vertical, downward direction. As a consequence, the amount of liquid is released from the decelerated valve member not only on the basis of inertia, but in addition by gravity.

[0006] The invention further relates to an appwatus for carrying out the methods according to the invention, comprising a valve including a body having an inlet and an outlet and a valve member adapted to close said outlet and movable perpendicularly to the plane of the outlet, the apparatus being characterized in that the valve member includes a shoulder which in the closed condition of the valve is in contact with the valve seat of the outlet.

[0007] In one embodiment of the apparatus according to the invention; the bottom surface of the valve member is co-planar with the end of the outlet in the closed position of the valve. The consequence of this construction is that the valve member pushes the last quantity of liquid through the outlet, which means that when the last quantity of liquid has been pushed through the outlet the entire outlet is filled by the valve, so that no liquid can remain behind in the outlet. At the same moment, the shoulder of the valve member strikes the seat, so that the valve member is abruptly stopped. As a consequence, the contact between the valve member and the liquid is broken, so that the liquid is moved along into the container and does not cling to the valve, thus preventing the latter from starting to drip. Preferably, the transition between the shoulder and the valve member is rounded, and the associated part of the valve seat is similarly rounded. The result of this rounding is that the valve member is centred as it is pushed into the outlet. As it is further pushed through the outlet, the valve member will then come to lie in proper sealing relationship with the inner wall of the outlet. As the valve member moves into the outlet, liquid present between the valve member or the shoulder and the valve seat is pushed back into the valve along the rounded surfaces, so that, in the closed condition of the valve, no liquid can be present between the valve member and the valve seat.

[0008] In order to prevent, as much as possible, that any liquid clings to the valve member, the valve member may be made of polytetrafluoroethylene. Furthermore, the valve seat may be made of stainless steel, which can easily be cleaned. Such a combination of polytetrafluoroethylene and stainless steel additionally provides for proper guideance of the valve member in the outlet.

[0009] One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings. In said drawings:

Fig. 1 shows a valve with a drive and control unit fpr the valve member present in the valve; and

Fig. 2 shows a detail of the valve member according to the invention.

[0010] Referring to the drawings, there is shown a valve comprising a body 1 with an inlet 2 and an outlet 3. The outlet can be closed by a valve member 4 having a shoulder 5. Shoulder 5 rests upon a valve seat 6. The valve seat has a rounded edge and terminates in a portion defining the outlet 3. In the closed position of the valve, valve member 4 fills the entire outlet 3, while the rounding between shoulder 5 and valve member 4 is in contact with the rounded edge of the valve seat. Valve member 4 is coupled at the top to a driving rod 7. The valve member can be fixedly connected to the driving rod, for example, by means of bolt 8 via bores 9, 10 and 11 (see Fig. 2).

[0011] At the top of the body, rod 7 is mounted for axial movement by means of a bearing 12 provided with seals 16 and 17. The axial movement of the driving rod can be effected with a pneumatic driving system 13 arranged above the valve. For this purpose, driving rod 7 is connected to two cylinders 14 and 15, arranged in series, and together providing for a stepped length of stroke of driving rod 7. The driving system is shut off from its surroundings by a cover 18.

[0012] When liquid has to be dispensed, for example, a container should be filled, valve member 4 will be raised under the influence of cylinders 14 and 15 and driving rod 7. Liquid can then enter valve 1 through inlet 2 and leave it through outlet 3. When the desired quantity to be withdrawn has almost been reached, valve member 4 is moved downwards at a high velocity by means of cylinders 14 and 15 and driving rod 7. During this movement, the last amount of liquid will be pushed by the valve member through the outlet 3 as a lump. At the moment when all liquid has been pushed through the outlet, and the bottom surface of valve 4 is co-planar with the outlet end, shoulder 5 strikes seat 6 with some force.

[0013] As a consequence, the valve member is instantaneously stopped, while the contact between the liquid and the valve member is broken as a result of the inertia of the liquid.

[0014] As the valve member enters the outlet, it is centred to some extent by the rounded edges of valve seat 6. Subsequently, valve member 4 will come to lie in contact with the valve seat, and any liquid remaining between valve seat 6 and valve member 4 will be forced back into the valve until shoulder 5 is in contact with valve seat 6 and no liquid is left between valve member 4 and valve seat 6.

Claims

1. A method of dispensing a viscous liquid, using a valve comprising a body having an inlet and an outlet and a valve member movable perpendicularly to the plane of said outlet, characterized in that, as soon as virtually the entire desired quantity of liquid has passed the outlet the valve member is moved to the outlet at a high velocity, so that the last quantity of liquid is pushed through the outlet, and is suddenly decelerated upon closing the outlet.

2. A method as claimed in claim 1, characterizing in that the valve member is decelerated shockwise in a plurality of steps.

3. A method as claimed in claim 1 or 2, characterized in that the liquid is pushed onward in the vertical, downward direction.

4. Apparatus for carrying out any of the methods as claimed in the preceding claims, comprising a valve including a body having an inlet and an outlet and a valve member adapted to close said outlet and movable perpendicularly to the plane of the outlet, characterized in that the valve member includes a shoulder which in the closed condition of the valve is in contact with the valve seat of the outlet.

5. Apparatus as claimed in claim 4, characterized in that, in the closed position of the valve, the bottom surface of the valve member is co-planar with the end of the outlet.

6. Apparatus as claimed in claim 4 or 5, characterized in that the transition between shoulder and valve member is rounded and that the associated part of the valve seat is similarly rounded.

7. Apparatus as claimed in any of claims 4-6, characterized in that the valve member is made of polytetrafluoroethylene.

8. Apparatus as claimed in any of claims 4-7, characterized in that the valve seat is made of stainless steel.

Drawing