System for measuring and controlling the angular position of the vessel of membrane presses in general

Abstract

 A system for measuring and controlling the angular position of the vessel in horizontal membrane presses comprises a rotary coder device (2) associated with the longitudinal axis of the vessel and arranged to constantly measure the actual position of the vessel relative to a reference position, and an operating and control unit (3) operationally connected at its input (A, B) to said decoder and at its output (C) to the vessel drive unit (1), and comprising at least memory means arranged to memorize specific angular operating positions of the vessel, and at least means (30) for selecting said specific angular positions; said unit being arranged to compare the actual position of the vessel with said specific memorized positions, such that each time the former coincides with one of the latter the unit emits a signal to halt the drive unit or to restart it in one direction or the other.

Description

[0001] This invention relates in a totally general manner to horizontal membrane presses and more particularly to a system able to constantly measure and control the angular position of the vessel of such presses.

[0002] These latter are known to comprise a horizontal cylindrical vessel rotating about its longitudinal axis and divided into two diametrically opposing parts by a deformable membrane.

[0003] The product to be pressed is fed into one of these parts, and a pressurized fluid such as air is fed into the other part to press the membrane against the product, from which the juice emerges and is conveyed to the outside of the vessel.

[0004] One of the problems encountered in using such presses is that of controlling the various positions which the vessel is to occupy during a complete pressing cycle, which comprises loading the product to be pressed, pressing it and then discharging the dregs.

[0005] A widely known method is to provide on the vessel hub the required number of projecting elements angularly adjustable about said hub, and associate said elements with a corresponding number of feelers, for example in the form of microswitches or the like, these being connected to the vessel drive system.

[0006] Although this method has proved satisfactory for processing cycles comprising a relatively small number of possible angular positions for the vessel, it has proved unsuitable for modern processing cycles, typically for products of special quality. In this respect, a complete pressing stage for such products comprises various successive pressing periods in which the product is subjected to gradually increasing pressure, between one and the next of said periods there being created, at least once, a vacuum behind the membrane while the vessel continues to rotate.

[0007] This is to disintegrate the previously compacted mass of dregs and enable all the juice to be extracted from them.

[0008] In addition, during said disintegration periods the vessel is very often rotated alternately in one direction and the other through different angles, so as not to subject the product to too energetic movements which could negatively influence the organoleptic characteristics of the juice. Basically, in such processing cycles the number of possible angular vessel positions which have to be controlled is particularly high, and the same positions can at least partly vary as the product being processed varies, with the result that the aforesaid known method has proved inconvenient.

[0009] This is because as the number of positions to be controlled increases, the number of projecting elements to associate with the hub varies correspondingly, these latter having to be adjusted manually with the vessel at rest, such manual adjustments being of relatively poor precision.

[0010] The object of the present invention is to obviate the aforesaid problems within the context of a simple and reliable arrangement which is easy to adjust with the necessary precision even with the vessel in movement.

[0011] Said object is attained according to the invention by associating with the press vessel, for example at a hub, a rotary coding device, ie a device which is able, starting from a reference or initial position, to measure the total angular path undergone by the vessel.

[0012] Said reference or initial position can for example be the position in which the product to be pressed is loaded, said rotary coder being arranged to feed signals to an operating and control unit which is itself connected to the vessel drive unit.

[0013] By virtue of the combination of the aforesaid means, the effective or actual position of the vessel can be monitored, and said actual position can be constantly compared with the predetermined positions preset in the operating unit, so that each time there is coincidence between the actual position and a preset position, the drive unit is caused to stop, or to reverse its direction, or to restart after a predetermined halt period.

[0014] The operating unit, preferably of electronic type, comprises data memory means, data input means, data display means and self-­diagnosis means, and the coder can consist of a pair of coaxial discs fixed to a hub of the vessel, with which corresponding sensors are associated to determine the complete and partial revolutions respectively.

[0015] Finally, the precision of the vessel angular positions corresponding to partial revolutions thereof is ensured by one of the discs being in the form of a ring gear having a large number of teeth, each corresponding to a fraction of a revolution (360°/number of teeth).

[0016] For example the number of said teeth can be 240, with said ring gear preferably being that used for rotating the vessel.

[0017] All the objects of the invention are therefore attained in that only one coder is provided independently of the number of angular positions to be controlled. Said positions to be controlled can be adjusted, or positions added, or some suppressed, at any moment, even with the vessel moving. Said adjustments and variations can be effected with optimum precision.

[0018] The characteristics and merits of the invention will be apparent from the description given hereinafter with reference to the single accompanying figure, which represents a schematic illustration thereof.

[0019] Said figure shows a drive unit 1 for rotating the vessel (not shown) of a usual horizontal membrane press, a rotary coder 2 associated with the longitudinal axis of said vessel, and an electronic operating and control unit 3 the input of which is connected to said coder 2 whereas its output is connected to said drive unit 1.

[0020] Said coder comprises two discoidal members 20 and 21 coaxial with each other and with the vessel axis, and with which respective sensors 200 and 210 are associated.

[0021] According to the invention said discoidal members 20 and 21 consist advantageously of one of the vessel support hubs and the vessel driving ring gear respectively.

[0022] In addition, a drive chain 11 passes endlessly about said ring gear and a sprocket wheel 10 driven by the unit 1.

[0023] Said ring gear 21 comprises a large number of teeth, for example 120 or 240, and a radial peg 201 is associated with the hub 20.

[0024] This latter can have any radial position, which preferably corresponds to the position in which the vessel is ready for loading the product to be pressed.

[0025] The sensors 200 and 210, for example in the form of magnetic proximity switches, feed a signal -A- and -B- respectively, each time they sense the respective passage of the peg 201 and of a tooth.

[0026] In other words the peg 201 defines a reference position and enables the unit 3 to count the complete revolutions of the vessel, whereas the toothing of the ring gear 21 enables partial rotations thereof to be measured, the unit 3 constantly comparing the actual position of the vessel with the programmed vessel positions which are memorized in the unit 3.

[0027] Each time this latter, which is simple to implement by an expert of the art, notices coincidence between said actual position and a programmed position, it feeds a signal -C- for halting the motor or for reversing its direction of rotation, or for restarting it after a predetermined halt period.

[0028] Finally, the same unit comprises data memory means, data feed-in means such as a keyboard 30, data display means such as an LED display 31, and self-diagnosis means.

Claims

1. A system for measuring and controlling the angular position of the vessel in horizontal membrane presses, characterised by comprising:
- a rotary coder device (2) associated with the longitudinal axis of the vessel and arranged to constantly measure the actual position of the vessel relative to a reference position, and - an operating and control unit (3) operationally connected at its input (A, B) to said decoder and at its output (C) to the vessel drive unit (1), and comprising at least memory means arranged to memorize specific angular operating positions of the vessel, and at least means (30) for selecting said specific angular positions,
- said unit being arranged to compare the actual position of the vessel with said specific memorized positions, such that each time the former coincides with one of the latter the unit emits a signal to halt the drive unit or to restart it in one direction or the other.

2. A system as claimed in claim 1, characterised in that said coder comprises two discoidal members (20), (21) coaxial with each other and with the vessel axis, one of which (20) being provided with a radial peg (201) defining the reference or initial position for monitoring the actual position of the vessel, and the other being provided with toothing having a large number of teeth, respective sensors (200), (210) being associated with said discoidal members.

3. A system as claimed in the preceding claims, characterised in that said discoidal members consist respectively of a support hub for the vessel and a ring gear which drives the vessel under the control of said unit (1).

4. A system as claimed in the preceding claims, characterised in that said ring gear comprises at least 120 teeth.

5. A system as claimed in the preceding claims, characterised in that said sensors (200), (210) are magnetic proximity switches.

Drawing