EP0226611B1

EP0226611B1 - A dosing device

Info

Publication number: EP0226611B1
Application number: EP19860903664
Authority: EP
Inventors: Hans Linner
Original assignee: Norden Pac Development AB
Current assignee: Norden Pac Development AB
Priority date: 1985-05-31
Filing date: 1986-05-27
Publication date: 1990-07-18
Also published as: SE8502681L; EP0226611A1; SE8502681D0; DE3672777D1; WO1986007117A1

Abstract

A dosing device comprising a dosing chamber having a plunge (19) arranged therein for reciprocating movement and an inlet (22) and an outlet (20) for the product to be volume dosed. The plunge is provided with an axial extension (21) which opens and closes, respectively, the inlet and the outlet dependent of the rotational position of the plunge relative the central axis thereof.

Description

The present invention relates to a device for the dosage of volume dosable products, for instance cream type products as tooth paste, construction paste, chewing gum, creams etc.
The problem behind the invention is to optimize the number of active elements and thereby reduce the number of sealings in volume dosing devices of the reciprocating plunger type.
Dosing devices of this general type have a plunger arranged for reciprocating movement in a dosage chamber and said plunger is provided with, in a conventional manner, for instance sealing rings and/or elastic sealing elements of the 0-ring type in order to provide a desired dosing pressure in a dosing chamber.
Prior art dosing devices have an additional movable element in excess to the plunger and said element is to be regarded as an active element for realizing the intended function. This further element (valve) normally is arranged as a ringshaped, cylindrical sleeve body having an opening in the sleeve. The sleeve is rotatable around the longitudinal axis of the dosing chamber, such that the opening in the sleeve may be brought in communication with either the inlet or the outlet.
This sleeve body (valve) requires sealing against the cylinder and, in practice, it means a need for at least one sealing location merely for this element, i.e. sealings around moving elements for rotating the valve.
In a low capacity pump for liquids, i.e. products of lower viscosity than cream type products, CH-A-128 278 discloses a plunger having a combined reciprocating and rotational movement. Additionally, US-A-1 001 872 discloses a similar movement pattern for an oil pump. Sealing problems make the two prior art low viscosity pumps difficult to use when high processing are required.
The device according to the present invention reduces the number of active elements and seals in a dosing device of the reciprocating plunger type and provides a pressure resistant, more reliable and cheaper structure than the known dosing devices.
The present invention provides a dosing device for volume dosable products, for instance paste type products, comprising a dosing chamber and an inlet and an outlet for the product connectable to the dosing chamber, and a plunger arranged for reciprocating movement in an extension of the dosing chamber. The dosing device is characterized in that the plunger comprises means forming an axial plunger extension, formed by a plate member having an axial length at least equal to the full plunger stroke length, that the plunger has members for rotation of the plunger around the longitudinal axis thereof to no more than two angular positions, that the outlet and the inlet are such that the inlet is fully open and the outlet closed by the plunger extension when the plunger, in one of said angular positions is drawn the whole plunger stroke length out from the dosing chamber, and that the outlet is fully open and the inlet fully covered by the plunger extension when the plunger, in the other one of said angular positions, is moved in a direction the whole plunger stroke length into the dosing chamber.
In one embodiment the plunger extension is arranged as a direct extension of the cylindrical envelope surface of the plunger around a portion of the circumference thereof.
In one embodiment the inlet and the outlet are arranged diametrically opposite each other at one end of the dosing chamber, and the plunger extension is arranged for being accommodated in a ringshaped extension chamber having a depth at least equal to the length of the plunger extension and arranged at said end of the dosing chamber.
In one embodiment the plunger is attached to a rod arranged for reciprocating movement and provided with manoeuvring members for placing the plunger in either of said two rotational positions.
One embodiment of the invention is illustrated on the accompanying drawing, where

Fig. 1 in a schematic, partly in section, longitudinal view shows a dosing device according to the invention, and
Fig. 2 is a section along line II-II in Fig. 1.

In a housing 10 supported in a stand (not shown) there is arranged a cylindric dosing chamber 11 and a ringshaped, cylindric extension chamber 12 arranged axially in register with the dosing chamber.
A plunger rod is journalled in the housing 10 for reciprocating movement in the direction of the double arrow 15. The plunger is also arranged for rotational movement around the common axial longitudinal axis 16 of the dosing chamber and the plunger rod. The axial movement as well as the rotational movement is accomplished by conventional means, as schematically shown at 18 in Fig. 1.
The plunger rod is attached to a plunger 19 acting as "pump plunger" in the device. In a conventional manner the plunger is sealed, at 20, against the chamber 11 such that it resists the over pressure, of several bars, obtained in this particular case.
A skirt or screen 21 forms an axial extension of the plunger and is arranged as a direct continuation of the envelope surface of the plunger. The skirt extends approximately 180° around the circumference of the plunger in the actual embodiment.
The ringshaped extension chamber is dimensioned such that it fully accommodates the skirt when the plunger is in the position according to Fig. 1. The width of the ringshaped gap of the chamber is such that the plunger 19 with the skirt integral therewith is allowed to reciprocate and rotate when members 18 for such operation are activated.
In the groove 12 there will be filling goods. This does not affect the function as the plunger 19 accomplishes the sealing against the critical side, i.e. to the right in Fig. 1. The dosing volume will neither be affected as it is possible to compensate for the volume of the fillings goods in the extension chamber by giving the dosing chamber 11 a nominal size taking in account the "rest volume" in the extension chamber 12.
An inlet 22 is arranged at one end of the dosing chamber 11. An outlet 23 is located diametrically opposite to the inlet.
In Fig. 1 the plunger 19 has just fulfilled the stroke thereof for discharging the product through the outlet 23.
The next step will be to activate the members 18 for rotation approximately 180° of the plunger rod 14, the plunger 19 and the skirt 21. Thereafter the members 18 are activated for an axial withdrawal of the plunger and the skirt member integral therewith. This skirt member will cover the outlet 23 progressively such that the outlet is fully covered when the inlet 22 is fully open.
The filling goods is brought to flow into the dosing chamber until the intended volume has been reached by placing the plunger in the right hand end position thereof.
Hereby the members 18 again are activated for withdrawing the plunger and the skirt integral therewith to a position where the skirt covers the inlet 22 and the outlet is open.
During the following forward movement of the plunger (to the left in Fig. 1) the product/filling goods is pumped out through the outlet 23 till the end position according to Fig. 1 is reached.

Claims

1. A dosing device for packaging machinery intended for volume dosable products, for instance paste type products, comprising a dosing chamber (12) and an inlet (22) and an outlet (23) for the product connectable to the dosing chamber, and a plunger (14) arranged for reciprocating movement in an extension (11) of the dosing chamber, characterized in that the plunger comprises means forming an axial plunger extension, formed by a plate member (21) having an axial length at least equal to the full plunger stroke length, that the plunger has members (18) for rotation of the plunger around the longitudinal axis thereof to no more than two angular positions, that the outlet (23) and the inlet (22) are such that the inlet is fully open and the outlet closed by the plunger extension (21) when the plunger, in one of said angular positions is drawn the whole plunger stroke length out from the dosing chamber, and that the outlet (23) is fully open and the inlet (22) fully covered by the plunger extension when the plunger, in the other one of said angular positions, is moved in a direction the whole plunger stroke length into the dosing chamber.

2. A device according to claim 1, characterized in that the plunger extension (21) is formed as an integral part of the cylindrical envelope surface of the plunger along a part of the circumference thereof.

3. A device according to claim 2, characterized in that the inlet (22) and the outlet (23) are arranged diametrically opposite each other at one end of the dosing chamber (11) and that the plunger extension (21) is arranged for being accommodated in a ringshaped extension chamber (12) having a depth at least equal to the length of the plunger extension arranged at said end of the dosing chamber.

4. A device according to anyone or any of the preceeding claims, characterized in that the plunger is attached to a rod (14) arranged for reciprocating movement and provided with manoeuvring members (18) for placing the plunger in either of said two rotational positions.