The present invention relates to a vacuum loader adapted for conveying granular material from a reservoir into a receptacle, the vacuum loader comprises a housing having an upper housing portion, a lower housing portion and a central housing portion between said upper housing portion and said lower housing portion, a granular material intake at the upper housing portion, a vacuum outlet at the upper housing portion, a granular material outlet at the lower housing portion, a closure member configured for opening and closing the granular material outlet, and operating means adapted for moving the closure member between an open position in which the granular material outlet is open, and a closed position in which the granular material outlet is closed.

US patent application no. 2014/205386 Al discloses a vacuum loader for downward discharge of granular resin material to resin material processing equipment, such as for supplying granular plastic resin pellets to gravimetric blenders and other devices, which operate in a vertical orientation.

This known vacuum loader has, as other conventional vacuum loaders, a housing with a diameter substantially larger than the diameter of the outlet for the granular resin material. Thus the housing tapers into the outlet for the granular resin material, basically in view of promoting downward gravity- induced flow of granular material to the material processing equipment. The outlet for the granular resin material does however constitute a constriction of the flow channel for the granular resin material, thereby increasing the risk of granules or particles building up in the outlet, and resulting in granular matter packing and obstructing said outlet. The consequence thereof is blocking of flow passage and a substantial and costly disturbance of the feeding process to the equipment .

Typically the granular resin material is a homogeneous composition comprised of small pellets of substantially same shape and size, such as of more or less spherical of tubular pellets. Such shapes rarely pack when transported by known vacuum loaders. However recycled plastic materials are often downsized into inhomogeneous compositions of flakes or chips of irregular outlines, shapes and sizes. Moreover they tend to stick together, thereby increasing particle sizes.

Prior art vacuum loaders have lower housing portions configured as hoppers with a main hopper body that receives the particles from the housing portions above. Said lower housing portion is defined by a circumferential hopper wall tapering towards a small granular material outlet. This known design is chosen to guide and concentrate the downward gravity flow of granular material towards the receptacle, which typically is the hopper of a conveyer for a molding machinery. For many kinds of granular material this known design is very efficient, however when transporting a flow of inhomogeneous granular material the narrow granular material outlet becomes a bottle neck that easily pack. If packing takes place the conveying process must be temporarily stopped to remove the obstruction thereby resulting in production stop. Frequent production stops take time and increase maintenance costs and operational costs, and should be avoided to the largest possible extent to maintain a continued production process. In respect of the known vacuum loaders the granular material outlet is a bottle neck irrespective of the kind of receptacle.

The granular material outlet of known vacuum loaders is made to open and close by means of a pivotally or radially displaceable flap closure. Residues of granular material may however remain on the flap closure after emptying the housing, so that once the flap closure is closed again for the next filling sequence, the flap closure cannot close the granular material outlet tightly .

It is a main aspect of the present invention to provide an improved vacuum loader of the kind mentioned in the opening paragraph .

In a further aspect of the present invention is provided a vacuum loader of the kind mentioned in the opening paragraph, which vacuum loader is particular efficient for conveying downsized, recycled, plastic material into receptacles.

In a further aspect of the present invention is provided a vacuum loader of the kind mentioned in the opening paragraph, which vacuum loader has a granular material outlet that is less susceptible of being obstructed in operation by packing of granular material compared to conventional vacuum loaders.

The novel and unique features whereby these and other aspects are achieved according to the present invention consist in that the closure member is a cone or frustum of a cone, which cone or frustum of a cone has a base part dimensioned to close the granular material outlet and an apex part facing towards the upper housing portion.

Actuated by the operating means the conical or f rusto-conical closure member moves along the axis of the housing in a linear motion to and from the upper housing portion, thereby making the base part to cover and close the granular material outlet to fill the housing with granular material, respectively to uncover and open the granular material outlet to discharge the granular material from the housing. The inclined circumferential wall of the cone or cone of a frustum directs granules or particles towards the granular material outlet and thus towards the base part, that during filling constitutes the floor of the housing. Within the scope of the present invention a receptacle can be any container for temporary storage of granular material or be part of a molding machinery.

The granular material is loaded into the housing of the vacuum loader by applying a vacuum to the granular material intake, e.g. using a vacuum pump coupled to the vacuum outlet as the suction point. Any means that is able to provide sufficient negative pressure to draw the granular material into the housing may serve as a "vacuum pump" and is within the scope of the present invention. When vacuum is applied a negative pressure is applied to the closure member as well. As a result the vacuum used to transport granular material inside the housing also initiates that the closure member moves upwards and inside the granular material outlet. In some embodiments the negative pressure may on its own suffice to make the closure member close the granular material outlet sufficiently during filling of the housing, whereby the granular material outlet inherently opens when suction is disrupted.

It is however preferred that the operating means comprises a means for actuating a reciprocating linear motion of the closure member at least partly in and out of the housing, thereby keeping the opening and closing of the granular material outlet under separate control. The means for actuating a reciprocating linear motion may be operatively connected to the apex part of the cone or frustum of a cone to reciprocate said cone or frustum of a cone between the open position and the closed position to ensure a tight closing of the granular material outlet. In this preferred embodiment a final tight closing of the granular material outlet is mainly achieved by the means for actuating a reciprocating linear motion of the closure member. Also the later opening of the granular material outlet may be achieved by the means for actuating a reciprocating linear motion of the closure member when vacuum application is stopped.

Both opening and closing may be due to a combined action of the suction associated with the intake of granular material into the housing and the reciprocation of the means for actuating a reciprocating linear motion of the closure member.

In order to ensure an airtight seal between the granular material outlet of the lower housing portion, said lower housing portion may be provided with a sealing gasket along a free rim of the lower housing portion, or the closure member may be provided with such a sealing gasket in the vicinity of the base part. The sealing gasket may be made of any appropriate resilient material, including but not limited to silicone or natural rubber.

Preferably the means for actuating a reciprocating linear motion is a pneumatic cylinder, such as a single action cylinder or a double acting cylinder that can produce a force in a reciprocating linear motion. As the piston of the pneumatic cylinder is secured to the apex part of the cone or cone of a frustum, said cone or cone of a frustum can easily be raised into the position in which the granular material outlet is closed, optionally plugged, by said cone or cone of a frustum as long as needed until the housing has been filled to a predetermined degree or level and must be emptied into the receptacle to be filled with the granular material. At that stage the piston moves in the opposite direction away from the upper housing portion thereby forcing the cone or cone of a frustum free of the granular material outlet whereby the granular material is set free to flow into the receptacle by gravity .

Although a pneumatic cylinder is described above as the preferred means for achieving the required reciprocating linear motion, other means that are suited to perform a reciprocating linear motion of the closure member are within the scope of the present invention.

The delay until the granular material reaches the housing from its reservoir may suffice for the pneumatic cylinder to efficiently close the granular matter outlet before the granular material reaches the lower housing portion.

Any means for actuating a reciprocating linear motion of the closure member is within the scope of the present invention, including means unrelated to the means for applying suction to the housing. The means for actuating a reciprocating linear motion of the closure member can be driven by an electric motor, e.g. in combination with an exterior pin and rack arrangement, be a hoisting arrangement, or be a hydraulic cylinder .

For very small batches, at inaccessible locations, and insufficient equipped sites of use the means for actuating a reciprocating linear motion of the closure member may simply be of the kind which can be operated manually, such as a simple reciprocating rod the vertical position of which can be secured, e.g. by locking means during conveying of the granular material into the housing.

In an advantageous embodiment the housing may be a cylinder, wherein the diameter of the upper housing portion, the lower housing portion and the central housing portion are substantially the same thereby advantageously ensuring a maximum diameter of the granular material outlet so that it does not becomes a bottle neck, and thereby facilitating very fast emptying of the housing.

Conveying of plastic granules or particles may often accumulate a very high static charge, in particular when conveying recycled plastic. This results in dust attraction on to the parts on the conveyor system, including hoses, vacuum loader and receptacle. The plastic granules or particles stick to surface of the conveyor system and to each other and may combine into larger combined particle structures, in the following called clumps. As a remedy to this problem the housing of the vacuum loader of the present invention may have a granular material bouncing member above the closure member to disintegrate the clumps of granular material. When the clumps hits on the granular material bouncing member the clumps disintegrate easily into the individual granules or particles.

In one embodiment the granular material bouncing element may comprise a ring element, a plurality of spaced apart rods may each have an upper end secured to the ring element and a lower end secured to the apex part of the cone or frustum of a cone to delimit openings between said rods, wherein each rod may have at least one lateral branch rod with a free end protruding in the direction towards the closure member.

Several lateral branch rods may be distributed along the length of one or more of the rods. This design of a granular material bouncing member allows granules or particles to pass through the openings and exposes plural opportunities, both vertically and radially, for clumps of granules or particles to hit on to disintegrate into its constituent of granules or particles. Optionally each rod may have at least two lateral branch rods having a common point of securing to the respective rod and having diverging free ends. Additional lateral branch rods may be provided in relation to the ring element or the rods, e.g. one or more lateral branch rods may protrude from the ring element, e.g. away from the central axis of the housing or parallel to said axis. Further lateral branch rods may be secured along the length of the rods, as expedient to disintegrate clumps. In a special construction of the granular material bouncing member one or more of the rods may have a first rod segment extending parallel to the central axis of the housing, which first rod segment may extend into an inclined second rod segment having the lower end, which lower end is secured to the apex part of the cone or frustum of a cone.

Preferably the first rod segment may extends into the second rod segment at the common point of securing of one or more lateral branch rods to said rod. Optionally the first rod segment is twisted at least 30° about its longitudinal axis, preferably at least 45°, more preferred at least 60°.

The granular material bouncing member may thus appear as a funnel-shaped lattice with large openings and a lot of protruding bouncing elements for clumps to hit on to achieve disintegration of the clumps.

The operating means may comprise a control system adapted for controlling the movement of the closure member and the filling of the housing with granular material in response to one or more operating signals, wherein an operating signal is selected from the group of signals comprising a signal from a level sensor, that is arranged in the receptacle, of the level of granular material in said receptacle, a signal of the position of the closure member, a start signal to start suction to fill the housing with granular material, a stop signal to stop suction of granular material into the housing, wherein any of said signals are send automatically by the control system to the operating means as continuous signals, or at selected intervals. Set points for the signals can be manually to software of the control system from one or more input devices associated with the control system and the operating means.

The control system and the operating means may provide an automatic filling process that can be conducted without substantial human interaction between the start and ending of a continuous sequence of repeated cycles, wherein each cycle comprise filling of the granular material into the housing from the reservoir, and discharging of the granular material into the receptacle, and wherein the sequence is automatically terminated when a predetermined level of filling of the receptacle is reached as signaled by the level sensor. At the end of the sequence of cycles the cone or frustum of cone is left displaced from the granular material outlet which is thus left open until the next operation.

The vacuum loader of the present invention is particularly advantageous for use with granular material that is recycled, downsized, plastic material, such as granules or particles in form of flakes or chips, due to a.o. the large granular material outlet and the vertical displaceable cone or frustum of a cone.

The present invention further relates to a method of filling a receptacle with granular material from a reservoir using the vacuum loader described above.

The method comprises the steps of a) arranging the vacuum loader in operative condition above the receptacle, b) arranging the level sensor in relation to the receptacle and in electronic communication with the control system to send a start level signal to said control system with information of the current level of granular material in the receptacle, c) the control system controls the operating means to

(i) close the granular material outlet by moving the closure member towards the upper housing portion,

(ii) start suction to transfer granular material from the reservoir into the housing in a transfer period, (iii) stop suction after end of the transfer period,

(iv) open the granular material outlet by moving the closure member away from the lower housing portion, and

(v) empty the housing of granular material, d) repeating steps (i) - (v) of step c) until the level sensor registers that a predetermined filling level of the receptacle has been reached and sends a stop level signal to the control system to stop the operating means .

The invention will now be described in further details with references to the drawing in which an exemplary embodiment of a vacuum loader is described.

Fig. 1 is a perspective view of a vacuum loader in closed position,

Fig. 2 is a perspective view of the vacuum loader of fig. 1 without the housing,

Fig. 3 is a perspective view of the vacuum loader of fig. 1 in open position,

Fig. 4 is a perspective view of the vacuum loader of fig. 1 without the housing and in the open position seen in fig. 3,

Fig. 5 shows the vacuum loader of figs. 1 - 4 during step (ii) of step c) ,

Fig. 6 shows the vacuum loader of figs. 1 - 4 during step (iv) of step c) , and

Fig. 7 shows the vacuum loader of figs. 1 - 4 during step (v) of step c) . In the below detailed description of an embodiment of a vacuum loader the term "cone" is used to cover a closure member in form of a cone or frustum of cone. Hoses and tubings for conveying granular material and vacuum are not discussed in the detailed description in that the skilled person is aware of such common structures. The vacuum pump and the reservoir of the granular material can be of any kind and is not discussed in further details.

As seen in figs. 1 - 4 a vertically arranged vacuum loader 1 of the present invention has a tubular housing 2. The tubular housing 2 has an upper housing portion 3, a lower housing portion 4, and a central housing portion 5. The tubular housing 2 is delimited by a circumferential housing wall 6, and at the upper housing portion 3 has a granular material intake 7 that can be placed under negative pressure through said circumferential housing wall 6 via an opposite vacuum outlet 8 at the upper housing portion 3 of the vacuum loader 1.

The lower housing portion 4 has a granular material outlet 9, through which a cone 10 can reciprocate, as seen best in e.g. figs . 5 - 7.

In figs. 1 and 2 the cone 10 is in a raised position actuated by the operating means 14 to cover the granular material outlet

9 to prevent granular material from escaping the housing 2 and to maintain the negative pressure needed to aspirate a batch of granular material from a reservoir (not shown) inside the housing 2.

In the closed position seen in fig. 1 the majority of the cone

10 is hidden inside the housing 2, and the base part 11 of the cone 10 tightly covers the granular material outlet 9.

The upper housing portion 3 comprises a detachable lid 12 held in place on top of the housing 2 by clamps 13. The vacuum outlet 8 is provided in the detachable lid 12, which detachable lid 12 facilitates quick access to the interior of housing 2, e.g. for maintenance purposes.

As shown in fig. 2 the operating means 14 of the vacuum loader 1 has a pneumatic cylinder 15 with a piston 16 having a piston end 17 secured to the apex part 18 of the cone 10. Once the pneumatic cylinder 15 of the operating means 14 is actuated by the control system (not shown) , compressed air enters the pneumatic cylinder at one of the sides of the piston 16 via a respective tube 19a, 19b and imparts a linear displacing force on the piston 16 in one of the directions up and down. In the alternative the piston 16 may drop due to gravity on relief of compressed air to thereby open the granular material outlet 9.

A sealing gasket 20 is provided around the base part 11 of the cone 10 to obtain an airtight coupling between lower housing portion 4 and cone 10.

The operating means 14 of the vacuum loader 1 further has a granular material bouncing element 21, which is secured to the apex part 18 of the cone 2 to come along with the cone 10 in the vertical linear motion when said cone 10 is moved in and out of the granular material outlet 9.

The granular material bouncing element 21 comprises a ring element 22, a plurality of spaced apart rods 23, in the present embodiment four rods 23, each having an upper end 24 secured to the ring element 22, and a lower end 25 secured to the apex part 18 of the cone 10 to delimit openings 26 between said rods 23 for easy passage of granules or particles of granular material, as shown in figs. 5 - 7. Each rod 23 has two lateral lower branch rods 27a having a common point 28 of securing to the respective rod 13 and diverging free ends 29a. Each rod 23 also has an upper lateral branch rod 27b secured at the vicinity of the end of the rod 23, which is secured to the ring element 22. A first rod segment 30 of the rod 23 extends parallel to the central axis X of the housing 2 and is twisted an angle of about 45° about its longitudinal axis. The first rod segment 30 extends into an inclined second rod segment 31 having the lower end 25.

In fig. 5 the vacuum loader is seen in step (ii) of step c) wherein granular material 32 is conveyed from a reservoir (not shown) , as indicated by arrow A, by application of suction to the granular material intake (7) . The granular material 32 is supplied into the housing 2 and delivered to the upper housing portion 3 of the housing 2 substantially at the longitudinal axis X to descend by gravity towards the cone 10. On its way downwards towards the cone 10 the granular material 32 passes by the granular material bouncing element 21 to disintegrate clumps of granules or particles, and step (ii) continues until a predetermined batch is inside the housing 2, such as when the housing 2 is between 50 - 80% filled. During filling the cone 10 tightly seals the granular material outlet 9.

Once the desired filling level of step (iii) has been reached suction is terminated, and the piston 10 moves the cone 10 away from the granular material opening 9 and away from housing 2, as indicated by arrow B, thereby allowing the granular material to get out of housing 2, as indicated by arrows C, to be collected inside the receptacle (not shown) .

As seen in fig. 7, in step (v) f step c) the granular material is almost out of the housing 2. If the level sensor (not shown) send a signal to the control system that the predetermined filling level of the receptacle has still not been reached step h) is automatically performed.

Once step h) is completed the vacuum loader may be left with the granular material outlet open until reuse. The vacuum loader of the present inventi on may comprise a single level sensor to be placed and recognized in a desired receptacle, or a plurality of receptacles may each have a level sensor that are recognized by the vacuum loader, so that once a receptacle of the plurality has been filled and moved to its next station a new receptacle can quickly be placed below the vacuum loader.

The plurality of receptacles may e.g. be places on a conveyor belt .