UNIT APT TO ACT UPON THE FLOW

Abstract: Means acting upon the flow, such as pumps or valves are used inter alia in the handling of liquid foodstuffs, e.g. milk, in packing machines. Since the demands on hygiene in this context are very high, especially if the packing machine operates with foodstuff sterilized beforehand, it is a disadvantage that manoeuvring devices for the means acting upon the flow have to pass from the outside into the sterile flow path where the means is located. This is avoided in accordance with the invention in that the means (3) acting upon the flow is combined with an actuator (8) which can be acted upon electromagnetically by a stator (7) isolated from the flow path.

Description: The present invention relates to a unit apt to act upon the flow comprising a driving means with a stator and an actuator connected to a device situated in the flow path which acts upon the flow. In the transport of fluids, especially liquids of different degrees of viscosity, devices acting upon the flow are used for the control of the flow rate. As examples of devices acting upon, or controlling, the flow may be mentioned various types of pumps, but also valves, throttles and similar devices, above all for the reduction of the flow rate. In the handling of certain types of fluids, e.g. liquid foodstuffs such as milk, sour milk, juice or the like very high demands are made on hygiene, so that the devices which are used e.g. for controlling the flow rate in these media must be designed so that they do not possess any complicatedly formed passages, pockets or other spaces which are difficult to clean. This is even more important in those cases where the fluid consists of a liquid sterilized beforehand, e.g. milk sterilized through heat treatment. This is often the case e.g. in packing machines where sterile milk is conducted continuously or in batches down into presterilized packing containers which are closed so as to be liquid-tight and microbiologically under sterile conditions. An uninterrupted sterility has to be ensured right from the sterilizer, where the fluid is sterilized, and up to the packing machine wherein the packing container filled with sterile contents is closed. The intermediate flow path thus not only has to be immaculate from a point of view of hygiene, that is to say it should be simple to wash and to sterilize, but it also has to be completely sealed off (also from a microbiological aspect) towards the non-sterile environment. It is an aim, therefore, that the flow path should not contain any manoevring devices such as movable axles or the like which extend into the flow path from the non-sterile outside. This is an aim, though, which until now has been difficult to achieve, since means acting upon the flow in the shape of pumps or valves necessary in the flow path had to be manoeuvred and controlled from the outside. Even though in practice it ought to be possible e.g. to build an enclosed, electric pump motor into a flow path, the movable part of the motor has to be sealed from the motor by means of a movable seal which, on the one hand, causes problems in connection with sterilization (thermal or chemical) of the device and, on the other hand, creates risks of a connection between the non-sterile interior of the motor and the flow path with non-sterility as a consequence. A unit as described in the preamble of claim 1 is known by DE-A 1 550 413. The valve of this unit is controlled by electromagnetic forces according to which a shaft on which the valve member is attached can be moved in a longitudinal direction with regard to the axis of the flow path. It is an object of the present invention to amend such unit in such way that further functions can be realized by simple means. The invention is claimed in claim 1: According to the invention the actuator and the shaft are rotatable around the axis extending in longitudinal direction of the flow path. That means that the shaft is movable not only in the axial direction but can also rotated which allows more options for controlling the flow. Further embodiments of the invention are claimed in subclaims. By designing the unit in accordance with the invention with the actuator situated in the flow path and mechanically separated from the stator ( "mechanically separated" here means that the actuator cannot be acted upon by mechanical means such as levers, shafts etc. from the stator, but is separated from the same by means of an uninterrupted, liquid and microbiologically tight barrier) it is made possible completely to avoid movable seals in contact with the contents. The unit, nevertheless will be drivable and controllable from the outside and will obtain a simple and purposeful design which, moreover, permits washing and sterilizing by known methods, e.g. hot steam, or chemicals. The arrangement will be simple and not highly cost-demanding at the same time as obtaining a sturdy construction which is suitable for handling of the most varied types of fluids. Finally the unit may be used optionally for different mechanical applications such as a pump or a valve arrangement. A preferred embodiment of the unit in accordance with the invention will now be described in greater detail with special reference to the attached schematic drawings which only show the details indispensable for an understanding of the invention. Fig. 1 shows partly in section a unit for flow control in accordance with the invention. Fig. 2 shows on a larger scale a part of the unit in accordance with Fig. 1 in cross-section. The unit in accordance with the invention is shown in its preferred embodiment as it can be designed for use in a packing machine of known type which portions out defined amounts of contents, e.g. milk, sour milk or juice, into preformed packing containers. The contents are passed to the packing container via a feed line 1, whose bottom end is designed as a filling pipe 2 with a device acting upon the flow in the form of a valve 3. The unit in accordance with the invention comprises a magnetically inductive flow meter 4, which is of a known type and generates a control signal which is passed to a control equipment 5. With the help of the control equipment, which compares the flow signal with a predetermined set-point curve, a control signal is generated to a driving means 6 for the valve 3 so that the flow through the filling pipe 2 is controlled to agreement with a predetermined value. When the flow meter 4 indicates that the desired quantity of contents has passed, the control equipment 5 gives a signal to the driving means 6 to urge the valve 3 towards the closed position which makes possible to fill with good accuracy each individual packing container with the desired amount of contents. The driving means 6 comprises a stator 7 firmly mounted around the upper end of the filling pipe and an actuator 8 placed inside the same in the flow path which is connected via a shaft 9 to the flow-controlling device or the valve 3 at the bottom end of the filling pipe 2. The shaft 9 is supported at its upper end in a bearing 10 which is held up by the bearing disc 11 firmly connected to the feed line 1. The bearing disc 11 is provided with flow passes 12 through which the pumped liquid fluid or the contents can pass. The shaft 9 is connected at its bottom end to a valve member 13 which comprises a number of flow passages 14. The valve member 13 rests with its bottom end against a valve seat 15 which has openings 16 corresponding to the openings 14. The valve member 13 is rotatable so as to bring the openings 14,16 straight before one another, or, in closed position of the valve 3, bring the openings 14 straight before a number of solid parts of the valve seat situated between the openings 16. The shaft 9 can perform a rotational movement as well as an axial movement. The latter means that the valve member 13 is lifted off the valve seat 15, which e.g. facilitates washing and cleaning of the valve, as will be explained in greater detail in the following. The driving means 6, as mentioned earlier, comprises the stationary stator 7 which is situated outside the flow path and is liquid-tight and microbiologically separated from the same with the help of the cylindrical wall of the feed line 1, and the actuator 8 which is situated in the flow path. The driving means, more particularly, is located in a widened part of the flow path which forms a chamber 17 whose inside diameter is only a few per cent greater than the outer diameter of the actuator 8. Beside the passage formed as a result between the outer surface of the cylindrical actuator 8 and the surrounding, cylindrical pipe wall, a passage 18 exists between the likewise cylindrical internal wall surface of the actuator 8 and the shaft 9. The flow area in this passage 18 corresponds substantially to the free flow area in the filling pipe 2. The actuator 8 is connected rigidly to the shaft 9 via a number of fixed arms 19 at the upper and lower end of the actuator. The stator 7 as well as the actuator 8, as mentioned earlier, are substantially cylindrical or annular and situated concentrically in relation to one another, and the actuator 8 is adapted to rotate the shaft 9 or be displaced in axial direction of the shaft 9 through action by means of the magnetic field of forces generated by the stator. To this end the stator 7 comprises an operating winding 20 around a stator core 21, this winding being adapted so as to be connected via the control equipment 5 and an electrical connecting line 22 to a source of current (no shown). Through this an electromagnetic field of forces is generated which influences an actuator magnet 23 so that the actuator 8 is rotated around the shaft 9. The actuator magnet 23 is displaced slightly in upwards direction in relation to the stator core of the operating winding 20 which means that the field of forces generated not only acts upon the actuator magnet 23 in rotational direction, but also seeks to urge the same to assume a position at a level with the stator core 21, which thus creates a downwards directed force which via the shaft 9 is transferred to the valve member 13 and causes thesame to rest against the valve seat 15. Beside the operating winding 20 the stator 7 comprises a solenoid winding 24 and a solenoid core 25 which are situated at some distance above the operating winding 20. The actuator 8 has corresponding secondary poles 26 which are slightly displaced downwards in relation to the solenoid core 25. When the solenoid winding 24 via a line 27 is fed with current from the control equipment 5 a magnetic field of force will act upon the secondary poles 26 so that these together with the actuator 8 and the shaft 9 are lifted slightly upwards in axial direction. This influences vis the bottom end of the shaft 9 the valve member 13 so that the same is lifted slightly from its contact against the valve seat 15. The driving means 6 comprises beside the two windings 20, 24 also a position indicator 28 which consists of two parts, namely a stator part 29 and an actuator part 30 surrounded by the same. The position indicator 28, which may be an angular position measuring system of conventional type, provides the control equipment 5 via the line 31 with a signal which gives information on the present rotational position of the actuator 8 in relation to the stator 7 thus providing a measure of the degree of opening of the valve 3 and being able to be used in combination with the signal from the flow meter 4 for controlling the current feed to the operating winding 20 so that the desired volume of flow per unit of time is obtained. When the unit in accordance with the invention is used in a packing machine of the conventional type for the proportioning out of liquid contents to packing containers placed at the bottom end of the filling pipe provided with a valve, first of all the set value which is to be applicable is transmitted to the control equipment 5, that is to say information regarding the quantity of contents which is to pass the flow meter 4 on filling of a packing container with the required quantity of contents, and possibly also a predetermined curve for the opening and closing of the valve 3. On starting of the packing machine contents are introduced in the first place so that the feed line as well as the filling pipe 2 will be wholly filled with contents. When production actually commences the valve 3 is opened in the first place owing to the control equipment 5 connecting the operating winding 20 to a source of current (not shown) so that a field of forces is created which acts upon the actuator magnet 23 so as to rotate via the fixed arms 19 the shaft 9, and with it the valve member 13, to the open position. In order to obtain a smooth opening process, the opening possibly may be done according to a predetermined opening curve which, as mentioned earlier, is programmed into the control equipment 5. The control equipment 5 is continuously informed regarding the present rotational position of the actuator 8 with the help of the position indicator 28, whose information concerning the angular position of the actuator 8 in relation to the stator 7 is fed continuously to the control equipment 5 via the line 31. As soon as the valve member 13 has been rotated to such a position that its flow passages 14 commence to overlap the flow passages 16 of the valve seat 15 the contents can flow out through the valve 3, and the flow of contents through the filling pipe 2, the feed line 1 and the flow meter is started. With the help of the flow meter 4 the control equipment 5 is informed continuously regarding the actual flow, and the opening area of the valve 3 is controlled by means of the control equipment 5 so that the required volume of contents is able to pass during the available time. When the correct quantity of contents for the filling of a packing container to the required level has passed the flow meter 4, the control equipment 5 acts upon the operating winding 20 via the line 22 so that the actuator magnet 23 rotates the actuator 8 to a position wherein the valve body 13 with the help of the shaft 9 is returned to its closed position. The closing of the valve 3 too may possibly be done according to a predetermined curve, the control equipment 5 being informed continuously of the angular position of the actuator 8 by means of the position indicator 28, as in the opening process. When filling contents of an uncomplicated behaviour a purely reciprocating control may be chosen, whereas contents which are difficult to handle, e.g. contents which tend to froth during the filling process, are handled better by setting the control equipment so that the opening as well as the closing process take place according to a predetermined curve appropriate for the particular contents. The filling process does not have to be controlled by a flow meter, but may also be coupled to some other measuring device, e.g. a level indicator or be time-controlled. The design of the unit in accordance with the invention with an actuator located in the flow path which is acted upon and is driven from the outside with the help of an electromagnetic field of forces makes it possible to maintain the flow path wholly separated from the environment, since any mechanical connection between the actuator part located in the flow path and means located outside the flow path is not necessary. As a result the wall of the chamber 17 can be made smooth and wholly without bushings for movable axles or other manoeuvring means, thus making it possible to meet the very high demands which are made on the handling of liquid foodstuffs and especially on the handling of such liquid foodstuffs which have been previously sterilized, e.g. through heat treatment. The design of the actuator with a large central flow passage 18 means that the contents can pass easily, and the absence of contact surfaces between movable and fixed parts (apart from the bearing 10) renders the arrangement very easy to clean and to sterilize. To this contributes, of course, also the simple design of the construction and the fact that the parts present in the flow path can be made of non-corroding material which, moreover, is resistant to normally used washing and cleaning agents such as steam and caustic soda. To facilitate the washing of the valve 3 as well as of the actuator 8 and the inner wall surface of the chamber 17, the actuator 8 together with the shaft 9 and the valve member 13 can be raised to an upper position or possibly oscillate between an upper and a lower position during the course of the washing. This can be achieved in that the solenoid winding 24 via the line 27 and the control equipment 5 is connected to an electric source of current (not shown) so that an electromagnetic field of force is generated which acts upon the secondary poles 26 displaced in a direction axially downwards towards the valve 3, so that they are lifted and centred in relation to the solenoid core 25. Through this the valve member 13 too is lifted off its contact with the valve seat 15 so that a passage is formed through which can pass the cleaning liquid or sterilizing medium. The movement of the actuator 8, on the one hand rotational and on the other hand upwards and downwards during the washing process facilitates the cleaning, not only in the space between the valve member 13 and the valve seat 15 but also in the space between the outer cylindrical surface of the actuator 8 and the interior wall of the chamber 17. The unit in accordance with the invention may be used also for the control of other types of devices acting upon the flow, e.g. other valve types, pumps or the like. The unit thus may be combined with valves of other types, e.g. axially movable valves, with the function of the windings 20, 24 being changed round so that the normal operating movement is axial whilst a rotary or twisting movement may be used in connection with the washing process. It is also possible to make the shaft 9 appreciably shorter or possibly eliminate it if the actuator 8 itself is designed as a valve body. The actuator 8 may also be designed as a pump rotor or a pump piston with rotary motion or axial motion respectively. Since the unit in accordance with the invention definitively solves previous problems and eliminates the need for a movable manoeuvring part which passes the delimiting wall of the flow path, a very great number of other types of pumps and valves too may be used of course within the scope of the concept of the invention.

Claims: Unit apt to act upon the flow comprising a driving means with a stator (7) and an actuator (8) connected to a device situated in the flow path which acts upon the flow, wherein the actuator (8) is connected to a shaft (9) and is situated in a chamber (17) which forms a part of the flow path and is surrounded by the stator (7) driving the actuator (8) by means of an electromagnetic field of forces wherein the actuator (8) is situated in the flow path and is mechanically separated from the stator (7) which is situated outside the flow path and is separated in an liquid-tight manner from the same, and wherein the actuator (8) is disposed around an axis extending in longitudinal direction of the flow path and is displaceable along said longitudinal direction, characterized in that the actuator (8) and the shaft (9) are rotatable around said axis extending in longitudinal direction of the flow path. Unit as claimed in claim 1, characterized in that the actuator (8) is connected to a valve member (13) rotatable between open and closed positions. Unit as claimed in claim 1 or 2 characterized in that the stator (7), beside windings (20) adapted to give the actuator (8) a rotary movement around its longitudinal axis, also comprises a winding (24) adapted to displace the actuator (8) axially so that the valve body (13) is liftet off the seat (15). Unit as claimed in one of the preceding claims characterized in that the actuator (8) is alternatively used as a pump body. Unit as claimed in one or more of the preceding claims, characterized in that driving means (6) comprises a position indicator (28) which is connected to a control equipment (5) for the control of the movement of the actuator (8). Unit as claimed in claim 5, characterized in that it comprises a flow meter (4) situated in the flow path whose output signal is conducted to the control equipment (5). Unit as claimed in claim 5 or 6, characterized in that the control equipment (5) comprises a programme for the manoeuvering of the actuator (8) in accordance with a predetermined curve. Unit as claimed in one or more of the preceding claims, characterized in that the flow path is microbiologically separated from the environment.

Inventors: ANDERSSON, SVEN-ARNE, SUNDBERG, ANDERS
Applicants: AB PROFOR
Application year: 1989
Main classification: F16K31
IPC codes: B67C3, A23C7, B65B1, F04D7, F16K31, F04B9, B08B9, G05D7, A23L2, F04B17