A PUMP DEVICE TRANSFERRING MASS
The invention relates to a pump apparatus conveying liquid or mass by means of a piston movable to and fro in a first and in a second direction in a cylinder, whereby the cylinder has an opening for suction of said material into the cylinder and an opening for removing said material from the cylinder and, further, the cylinder has an activator, such as a cylinder working with pressure medium, the piston rod motion of which is conducted as motion of the piston located in the pump cylinder.
Previously known are mass pumps, where a to and fro movable compression cylinder moves a piston furnished with valves in a separate cylinder tube sleeve, whereby, on the other hand, the mass is sucked into the cylinder sleeve by means of the piston and, on the other hand, pushed out of the cylinder sleeve by means of the piston.
The requirements of purity in the food industry have a significant position and in known solutions the piston rod of the compression cylinder is by means of a separate distance piece connected to the pump cylinder piston rod, whereby the cylinder space in the compression cylinder is completely separated from the pump cylinder space. As spindle of the pump cylinder constructions are known, where different kinds of valves, as clack valves, are built in connection with the piston, whereby said valves let material out through the piston in pumping direction through openings made through the piston. In these solutions the pump cylinder has to be made quite accurate as to its inner surface, among other things by machining, and where on the piston outer circle a ring sealing is fixed sliding on the said inner surface and tightening the sliding surface between piston and cylinder. In known clack valve constructions, as for instance according to publication EPO 0 499 596, the disadvantage is the inconvenient cleaning of the pump apparatus inner parts.
By means of the mass conveying pump apparatus as per the invention the above presented problems are solved and a significant improvement of the techniques prevailing in the branch is achieved. The invention is characterized in that there is in the piston one or more openings made in it for the material to be pumped to get through the piston, when the piston is moving in its first direction, and that there is in the piston a ring sealing arranged to move axially in the sealing housing formed in the piston so that the packing closes said openings, when the
piston is moving in its second direction.
The advantage of the invention is that no separate valve must be made in the piston, since the packing moving in its housing forms a flow hindrance for the material to be pumped so that the material does not pass the piston with the packing in closing position. The packing moving in its housing to the opposite position opens for the material a passage through the piston. The packing works reliably, while getting tightened by pressure both against its housing and the inner surface of the pump cylinder. The packing material can be a little softer than usual and more flexible, due to which an advantageous tube with not machined inner face and made of plate by bending and by longitudinal joint welding is well suited as pump cylinder. Only the inner face welded joint needs grinding. Due to the joints the pump cylinder can be opened and easily cleaned, likewise the piston can be easily dismantled and cleaned.
The piston rod of the actuating cylinder can enter uniform the pump cylinder, whereby in its end a pumping piston is fixed. The driving medium getting mixed in the material to be pumped is avoided by means of an open space with connection to open air and through which leaks of material escape.
In the following the invention is disclosed with reference to the enclosed drawing, where Fig. 1 is a side view of the pump apparatus partly cut. Fig. 2 is a cut side view of the piston.
Figure 1 shows a pump apparatus comprising a driving cylinder 3, which is for instance a compression cylinder furnished with a working piston or a cylinder working by water hydraulics. From cylinder 3 comes a piston rod transmitting to and fro motion through immobile packing pieces 13 and 14 into pump cylinder 1. Between packing pieces 13 and 14 An open space is formed, which has through nipple 17 free connection to open air. Possible material leaks pass out through the open space and do not continue from one cylinder space to another. Packing piece 13 has also a lip pressing rod 4, the purpose of which is to hinder the material to be pumped from entering open space 16.
The mass to be pumped is sucked from opening 7 by means of the rod 2 motion without hindrance from the counter valve, as ball 11, into cylinder 1. The mass leaves cylinder 1 from
opening 8. Piston 2 carries out the pumping motion, whereby it, as in the case in figure 1, conveys the mass on its upper side further from opening 8. Piston 2 the closes the cross- section of cylinder 1 near it. When piston 2 moves back its construction in the return state is presented by a piston 2' illustrated inside cylinder 1. Ring sealing 5 in piston 2' is in the return state in a position illustrated by reference number 5'. The enlarged figure 2 also illustrates the piston just in this state. In the returning state through piston 2 a material channel 10 is formed, when the lower portion 2a of piston 2 is loose with respect to cylinder 1 inner surface, whereby the flow of material circulates round the outer edge of portion 2a and continues further to the upper side of piston 2 through the openings of portion 2b.
According to figure 2 there is in piston rod 4 end 4a most suitably a threaded portion, on which both portions 2b and 2a of piston 2 can be screwed one after another. This piston is easily demounted off piston rod 4. For packing 5 housings 6 are formed in both portions 2a and 2b. The pressure difference acting over piston 2 moves packing 5 always automatically to proper housing position. The packing material is flexible plastic, such as heavy molecule polyethene UHMW-PE or PTFE. Then the packing adjusts itself both to its task to close the material flow through the piston and, on f e, pφer h n > P ig ten the piston against cylinder 1 inner face. Thus the cylinder inner face can be not-machined, that is made advantageously by bending and by welding of plate.
To make cleaning of cylinder 1 and parts included in it easier and to open its construction, the cylinder can be opened for instance in opening tightening band joints 18, some advantageous spots of which are illustrated in figure 1.