FR2492347A1 - Automatic hopper feed system for granules - with valve system to obtain pressure swings from solo non:reversible compressor - Google Patents

Abstract

In a process where a hopper is vacuum filled from a bulk container of particulate material and then discharged into a processing vessel or machine with pressure assistance, the pipework circuits of the vacuum compressor include a bank of valves such that the pressure in the hopper can be switched from suction to pressure without changing the direction of operation of the compressor. Suitable for loading e.g. plastics granules into blending or processing equipment, opt. in a system where the level in the machine is detected to trigger the closing of the loading valves, and/or where the contents of the vessel are also pneumatically agitated or fluidised. Avoids need for two compressors or alternatively repetitive several of a solo compressor, saving cost and wear.

Description

Method and device for self-feeding a machine with material in a divided state.

 The invention relates to a method of self-feeding in material in the divided state of a machine intended for the treatment of said material by air, and connected to the discharge side of a blower whose suction side is connected by a pipe. has an air filter, the method being of the type according to which: the material of a reservoir is passed, during at least a first so-called suction phase1, to a feed hopper, the upper part of which is connected to an alternative source of suction and pressure, is provided with a separation filter which filters the air used to transport the material, the intermediate part being connected by a pipe to said tank, and the lower part opening out, by means of a valve. in the processing machine; air from the pressure source is sent, during at least a second so-called unclogging phase, distinct from the first phase, through the upper part of the hopper and its filter so as to unclog it ci and to promote the descent of the material contained in the hopper towards the treatment machine, permanently, air is blown into the treatment machine by means of the blower with which it is provided.

 I1 is commonly used in the Plastics industry, feeders of materials working by pneumatic suction, that is to say by vacuum. This apparatus then essentially comprises a so-called high pressure blower, of a generally annular type, which is in direct relation with a hopper intended to receive the materials in the divided state thus sucked in, the air having served for transport being filtered before being passage through the blower through an appropriate sieve.

 This device requires, to avoid rapid fouling of the filter in question, a cyclical reversal of the direction of rotation of the blower in order to send, at the end of each cycle, pressurized air against the current to unclog the filter.

 The supply method used in industry hitherto therefore requires that the blower run alternately in both directions, and therefore frequent start-ups, succeeding dead times allowing the blower to stop.

 It is this kind of feeder that is used in particular to charge the ovens intended for drying the plastic granules1 ovens which can be of the pressurized type such as those known under the name of etuses-transîert, or of the conventional type not pressurized.

 It has been sought, under these conditions, to improve the complex system comprising both an oven equipped with a blower, and a feeder also having its own blower.

 The present invention sets itself in particular as the removal of the blower from the feeder (while maintaining all of the drying and feeding functions) and the elimination of dead times and cyclic starts, causes of wear of the equipment. .

These goals are achieved by the fact that
- a first valve is interposed on the connection between the blower and its air filter;
- the upper part of the hopper is connected on the one hand to the suction of the fan via a pipe fitted with a second valve, and on the other hand to the discharge of the fan via '' a pipe fitted with a third valve
- the three valves are kept closed, open and closed respectively during each suction phase -
- Maintaining the three valves respectively open, closed and open during each unclogging phase;
- Maintaining the three valves respectively open, closed and closed outside the suction and clogging phases.

 The invention also relates to a device for self-supply of material in the divided state of a machine intended for the treatment of said material by air, and connected to the discharge side of a blower whose suction side is connected by a ducted to an air filter, the device being of the type comprising a feed hopper, the upper part of which, connected to an alternative source of suction and pressure, is provided with a separation filter, the lower part of which opens out via a valve in the processing machine, and the intermediate part of which is connected by a pipe & a material reservoir.

 To allow the implementation of the method of the invention, the device of the invention is characterized in that the pipe connecting the blower to its filter is provided with a first valve, in that the upper part of the hopper is connected on the one hand to the suction side of the blower via a pipe provided with a second valve, and on the other hand to the discharge side of the blower via a pipe provided with a third valve and in that the device comprises means for controlling the valves.

 Advantageously, the valves are butterfly valves whose rotation is controlled, by means of rods, by electric jacks, controlled by a cam programmer.

 Advantageously, the cam programmer is controlled by a level controller placed in the processing machine.

 The simplicity of the system of the invention and its compact appearance make it possible to make significant progress in terms of the reliability of the economy of motive force and reduction of the noise level, a blower being always quieter than two blowers operating in the same time.

 Another particularity of the system described, in the context of an oven-transfer, is to allow a single blower of the high pressure type all of the functions of feeding granules to be dried by steaming with hot air, and transfer of the oven granules to the user hopper.

The characteristics and advantages of the invention will be better understood on reading the description of a particular embodiment which will be made with reference to the accompanying drawings in which
- Figure 1 shows an overall diagram of the self-feeding device according to the invention;
- Figure 2 is an elevational view with partial sections of the housing containing the valves of the device of Figure 1
- Figure 3 is a top view with partial sections of the shoemaker of Figure 2
- Figure 4 is an electrical diagram of the cam programmer controlling the mechanism actuating the valves of Figures 2 and 3.

 FIG. 1 shows the treatment machine 1, for example a pellet oven, equipped with a blower 2 supplied with air via a first air filter 3. A pipe 4 connects the air filter 3 to the suction 5 of the blower 2, while the discharge 6 of the blower 2 is connected by a duct 7 inside the treatment machine 1. On the ducts 7, a resistor 8 can be interposed, in particular in the case an oven intended to heat the process air. A transfer duct 9 allows the evacuation of the materials treated in the machine 1.

 A more detailed description of the processing machine is not necessary since it is not part of the invention per se. We can find specific examples of implementation in French patent applications 75 21 584 and 75 21 585 on behalf of the applicants.

 The processing machine 1 is supplied with material in the divided state 10 by a closed feed hopper 11, the upper part 12 of which is connected by a line 13-14 to the suction 5 of the blower 2.

 The cylindrical intermediate part 15 of the hopper 1.1 is connected by a line 16 (for example a feed rod) to a reservoir 17 containing the material 10.

 The intermediate part 15 and the upper part 12 are separated by a separation filter 18 which filters the air sucked in by the blower 2 and which has been used to transport the material 10 from the tank 17 to the hopper 11.

 The frustoconical lower part 19 of the hopper 11 opens out via a valve 20 in the treatment machine 1.

 A line 13-21 connects the upper part 12 of the hopper 11 to the discharge side 6 of the fan 2.

 A first valve 22 is interposed on the link 4 between the air filter 3 of the fan 2 and the suction 5 of the latter.

 A second valve 23 is interposed on the pipe 14 connecting the upper part 12 of the hopper 11 to the suction 5 of the fan 2.

 A third valve 24 is interposed on the line 21 connecting the upper part 12 of the hopper 11 to the discharge 6 of the fan 2.

 These three valves 22, 23, 24, advantageously grouped in a housing 25, are actuated by a mechanism 26 controlled by a programmer 27, according to a process detailed below.

 Blower 2 runs continuously.

During a first so-called suction phase, the valves 22, 23, 24 are respectively closed, open, and closed: the blower then draws air through the line 13, 14 (in the direction of the arrows 28), which allows the material 10 of the reservoir 17 to be sucked into the hopper 11: the separation filter 18 retains the material 10 in the hopper 11. This suction phase lasts sufficient time to allow the filling of the hopper il; this time is calculated according to the dimensions of the hopper and the suction power of the blower 2, and makes it possible to program the mechanism 26 so as to maintain the valves in the desired position during this time. During this first phase,
because the valve 24 is closed, the fan 2
fully expels air into the milking machine
1.

During a second phase, called dice
clogging, distinct from the first phase,
keeps the valves 22,23, .24 respectively open
closed, and open: the blower has sucked
air through its air filter 3, and expels it through its
delivery side 6, the shared air being shared,
between line 7 connecting
the fan 2 to the machine 1, and the pipe 21, 13,
in which the air flows in the direction of the arrows
29: the air thus arriving & against the current in the
upper part 12 of the hopper 11 allows unclogging
of filter 18 which became dirty during the phase
In addition, this air creates in the hopper
feeder, above the material 10 which is there
finds, an overpressure which favors the opening of the
valve 20 and the descent of the material 10 into the
machine 1 by increasing the pressure on
the valve due to the weight of the material; this is gone
particularly advantageous if the machine 1
It is itself pressurized. We see that, even during this second phase, blower 2, taking into account
of its relatively large power vis-à-vis
blowers commonly used on appliances
feeders (in an approximate ratio of 1.5
at 3) can, at the same time, discharge air to the
feed hopper 11, while maintaining a flow
of air to the heating resistor 8 and therefore
towards the oven 1 (taking place in the case of this mode
), which allows to maintain
still the steaming function1 all the more since this
second phase for cleaning the filter is
very short: of the order of a few seconds. Although the air flow circulating in line 7 is reduced compared to its maximum value, the Applicants have been able to calculate that the reduction in performance does not exceed in a way general 2% of production capacity. It should not be forgotten, in fact, that the unclogging phase only intervenes for a fairly short time: for example in an embodiment tested by the Applicants, for a 6 liter hopper, the suction phase lasted 36 seconds, and the 10 second unclogging phase1 with intermediate transient phases of 7 seconds (corresponding to the opening and closing periods of the valves); the capacities of the installation tested required six unclogging phases per hour.

 In order to fill the machine 1 to a suitable level, several successive feeding cycles each comprising a suction phase and an unclogging phase, may be necessary depending on the respective capacities of the hopper 11 and the machine 1. A level controller 30, for example of the rotary vane type, controls the start and stop of all the feed cycles, according to a process explained later.

 Outside the feed cycles, the valves 22, 23 and 24 are respectively kept open, closed and closed. The air from the blower 2 is sucked in via its filter 3 and entirely used for the treatment of the material of the machine 1, no flow circulating in the pipes 13,14,21.

 Figures 2 and 3 show a particular embodiment of all of the valves 22, 23 and 24. The support box 25, intended to receive the air flow reversal system is executed in mechanically welded sheet of 3 mm , is rectangular, and includes two removable covers one side 30 and the other upper 31 allowing the establishment of the three valves 22,23,24, and the necessary control parts.

 This box has six circular section openings 32 connected so that there are a total of the four necessary outlets: two outlets 5 and 21 to the suction and discharge of the blower 2, and two outlets 4 and 13 to the air filter from blower 2 and to the feed hopper.

 These outlets are arranged so that the air flow through the housing is optimal.

 The set of motorized valves 22,23,24, is composed of three butterfly valves, which are the least expensive, but it goes without saying that all kinds of valves such as valves with deformable membrane, and with sleeves) can be used .

The valves 22 and 23 have the same section, but the valve 24, used for unclogging the filter of the hopper 11, has a diameter smaller than two others.

 These valves are arranged in parallel on cradles 33 constituted by U-shaped irons, the whole being assembled on the housing 25 by stirrups 34 bolted 2 in number per valve, allowing easy replacement of the element.

 The valves are sealed against the walls of the housing by using an extruded rubber seal 35 with a U-profile, around 60 shore hardness, around the periphery of the valve.

 The butterflies of the valves are rotated 11 by means of two rods pinned on the axes of the valves: a single rod 36 actuates the valve 24, and a double bieilette 37 actuates simultaneously the two valves 22 and 23 whose axes are face to face and which are always out of phase.

 The movement of the two links 36 and 37 is ensured by two small electric jacks 38a and 38b, for example of the type whose longitudinal displacement is achieved by the drive of an endless screw rotating inside the rod of the jack, the screw being driven by a small single-phase motor via an incorporated micro-reducer. This solution is advantageous because it avoids being dependent on the presence of compressed air.

 Each electric actuator also includes two limit switches, the function of which will be explained with reference to FIG. 4.

 The jacks 38 are arranged outside the housing on welded supports 39, perpendicular to the removable cover 31p which includes passage openings 40 provided for this purpose.

 The electric control of the two cylinders is ensured by a cam programmer whose function consists in alternating the suction and unclogging phases of the hopper 11, thus ensuring, in a discontinuous manner, the supply of the oven 1 in dryer products as needed.

 stinking in the position corresponding to the operation of the machine outside of the feed cycles, it is obtained when the level controller 30 is in the stop position, which corresponds to the high level of the material 1C in the divided state in the processing machine 1.

 This position can also be obtained by the operation of a rotary button, which has the effect of short-circuiting the level controller.

 Although FIG. 1, for greater clarity, represents the various elements of the self-feeding device which are fairly sparse, it is clear that they can be grouped together: the box 25 attached to the machine 1, and the whole of the electrical control in the machine's electrical cabinet 11.

 FIG. 4 represents the electrical diagram of the cam programmer 27 allowing the realization of the supply phases according to the invention.

 The assembly essentially shows the electric jacks 38a and 38b, 38a operating simultaneously the two valves 22 and 23 and 38b operating the valve 24, each provided with their two limit switches 50a, 51a and 50b, 51b.

 These jacks 38a and 38b are each controlled by a switch 52a, 52b, itself actuated by a single cam 53 (split in the figure for the purposes of the representation) whose rotational movement is ensured by a motor 54.

 The motor 54 is supplied as a function of the reversing relay 55 tilting from one position to the other direction under the effect of the braking force of the paddles 56 of the level controller 30, the paddles 56 being driven in rotation by a motor. 57 independently powered by a current source 58.

 An on-off button 59 enables the level controller to be switched off. The assembly is supplied by a voltage source 60 and operates as follows.

 During the suction phase, the button 59 is as shown, the reversing relay 55 also and the cam 53 is in a position such that the contacts 52a and 52b are on the right (unlike the figure). The current then flows in the branches 61-62-63-64-65-66-67, then causing the actuator 38a to close the passage 22 of the air coming from the filter of the oven and to open the valve 23 towards the hopper. The current also passes through the branches 61-62-63-68-69-70-66-67, causing the jack 38b to close the passage 24 of the pressurized air taken from the oven.

 The duration of the suction is regulated by the profile of the cam 53, calculated or determined by experience so that the suction lasts the time of filling the hopper. During the entire feeding cycle, the cam 53 is driven by the motor 54 supplied by the circuit 62-63-71-72-66-67.

 When the cam 53 reverses the position of the contacts 52a and 52b (which then become as shown) begins the unclogging phase. The cylinder 38a opens the valve 22 and closes the valve 23, the current passing through the branches 61-62-63-73-6566-67. In parallel, the jack 38b opens the valve 24, the current flows through the branches 61-62-63-68-7470-66-67.

 The two phases are repeated until the rotary level controller 30 (located on the cover of the oven) is braked by the material and causes the reversing relay 55 to flip, which can occur during a suction phase or unclogging.

 The actuator 38a remains in the previously acquired position.

 The current flows through the branches 61-62 73-69-70-6S-67 and feeds the actuator 38b so that the latter closes the valve 24 (if it is not already).

 If the change-over relay 55 has switched during an unclogging phase, the motor 54 ceases to be supplied and the contacts 52a and 52b remain in the state.

 If the change-over relay 55 has switched during a suction phase, the motor 5 continues to be supplied by the circuit 61-62-63-75-76-68-7172-66-67 and causes the switching of the contacts 52a and 52b. The reversal of the contact 52b causes the power supply to the motor 54 to be cut off.

 The situation remains as long as the level controller is braked by the material.

 When the level of the material decreases, the braking decreases and the reversing relay 55 returns to its initial position; the feeding cycle starts again with a cleaning.

 The level controller must be taken out of service during the deceleration phase (indicated by the indicator light 77).

 The stopped position is identical to that commanded by the level controller. In no case does the stop cause cut off the power supply to the programmer before the cylinders have completed their orderly stroke.

 Obviously, this embodiment has only been described by way of example and it can be modified without departing from the scope of the invention defined by the appended claims.

Claims (7)

 1. Self-feeding process for material  the divided state (10) of a machine (1) intended for  treatment of said material by air, and connected to the  discharge side (o) of a blower (2) whose  suction side (5) is connected by a pipe 14)  to an air filter (3), the method being of the type -on which: passing, for at least one  first so-called suction phase, the material (1G)  from a reservoir (17) to a feed hopper (11)  of which the upper part (12), connected to an alter source  native suction and pressure, is provided with a  separation filter S18) which filters the air having  used to transport the material (10), the inter  medial (15) being connected by a pipe 116)  to said tank (17), and the bottom part (19)  edge by means of a valve (20) in the treatment machine (13; during  minus a second phase called unclogging, separate  from the first phase, air from the source  pressure, through the upper part (12) of the  hopper (11) and its filter (18) so as to unclog  this one and to favor the descent of the tale material  naked in the hopper (to the processing machine  (i) permanently, air is blown into  the processing machine (1) by means of the souf  floating (2) with which it is provided, this process being  characterized in that  - a first valve (22) is interposed on  the connection (4) between the blower (2) and its filter  air (3)  - we connect the upper part (12) of the  hopper (11) on the one hand to the suction (5) of the  blower (2) via a pipe  (13,14) provided with a second valve (23), and on the other hand with the discharge (6) of the blower (2) via a pipe (13,21) provided with a third valve (24)  - the three valves are kept closed, open and closed respectively during each suction phase  - the three valves are kept open, closed and open respectively during each unclogging phase  - Maintaining the three valves respectively open, closed and closed outside the suction and clogging phases. 2. Method according to claim 1, characterized in that the machine is fed (1) by a succession of feeding cycles each composed of a suction phase and an unclogging phase. 3. Method according to claim 2, characterized in that one starts and stops the supply of the machine (1) according to its level of material (10). 4. Method according to one of claims 2 and 3, characterized in that the feeding cycles are regulated by means of a cam programmer. 5. Device for self-feeding of material in the divided state (10) of a machine (1) intended for the treatment of said material by air, and connected to the discharge side (6) of a blower (2) the suction side (5) of which is connected by a line (4) to an air filter (3), the device being of the type comprising a feed hopper (11), the upper part (12) of which is connected to a alternative source of suction and pressure, is provided with a separation filter (18), the lower part (19) of which opens out via a valve (20) in the treatment machine (1), and of which the intermediate part (15) is connected by a line (16) to a reservoir (17) of material (10), characterized in that the line (4) connecting the blower (2) to its filter (3) is provided with 'A first valve (22), in that the upper part (12) of the hopper (11) is connected on the one hand to the suction side (5) of the blower (2) via a pipe ( 13,14) provided with a second valve (23), and d on the other hand to the discharge side (6) of the blower (2) via a pipe (13r21) provided with a third valve (24), and in that the device comprises means for controlling the valves ( 26,27,30). 6. Device according to claim 5, characterized in that the valves (22,23,24) are butterfly valves whose rotation is controlled by means of rods (36,37), by electric jacks (38), controlled by a cam programmer (27). 7. Device according to claim 6, characterized in that the cam programmer (27) is controlled by a level controller (30) placed in the processing machine (1).