Method and device for checking and controlling the filling of containers by a given weight of a product

The object of the present invention is a method and a container filling installation.

In many industries, food processing, chemical, petroleum, pharmaceutical, etc., we need to condition more or less fluid products for their subsequent distribution. To be profitable packaging operation should be both fast and accurate. On modern systems the speed is acquired but it is still trying to gain precision, the ideal in this area is to fill each container with exactly the amount of desired product. However, satisfaction of this second requirement, - accuracy, - faces several difficulties, mainly related to the required rapid pace of filling and the physical properties of the products to be packaged. The rapid filling rate makes it difficult to check the amount of product introduced into each container on the products to be packaged, even if they are homogeneous, their specific gravity and viscosity can vary with temperature, which influences their assay. However, if one wants to proceed to the accurate filling of containers scrolling on a filling arrangement in the chain, must firstly perform a correct dosage of the product to be packaged and on the other hand ensure that the filled containers contain well, - individually or statistically - and contain only the desired amount of product to be able, if necessary, modify the dosage for vessels appearing on the upstream carousel weighed container.

To perform the assay it is known to use volumetric feeders of the type comprising a timer which controls the opening and closing of the orifice of a reservoir to be packaged or of the type comprising a piston-cylinder unit wherein the piston stroke defines the volume to be introduced into the container. These metering devices are adjusted to deliver a given volume of product at a given temperature. If the temperature of the product introduced therein varies during a day, a few days etc., the quantity of product introduced in the containers vary. To check the amount of product introduced in the containers and modify the setting of the dosing to correct a lack or excess of any product, it is known to use a balance, only the weight to define exactly what a quantity of product in the temperature.

U.S. Patent US-A-2,925,835 discloses a method and a control device and controlling the filling of containers successively engaged in the channel filling installation. In the embodiment given in this patent, the containers are transported on a conveyor belt to a single filling station where they are filled alternately with a quantity of product dosed by a volumetric feeder with a timer. The filled containers continue their journey on the treadmill to a point where they are mechanically removed from the conveyor belt one after the other, placed on a fixed scale next to the treadmill, weighed, and then placed back on mechanically the treadmill. The container weight is compared with a reference value and if necessary, the volumetric feeder of the setting is changed. If it enables theoretically solve the problem, this device has some disadvantages in practice. On the one hand the transfer of the container Rouland carpet balance and balance to the treadmill and the weighing of the container, to be precise, must last a minimum time, do not allow a rapid filling rate. Moreover, on this device, it is not expected to tare containers. Or depending on the material they are made, the weight of the containers, even mass-produced, can vary significantly. This is the case of glass containers. So it is not possible to determine the exact weight of the contents of containers weighed.

US-A-2961013 discloses a container filling installation by means of volumetric devices each having a piston moving in a cylinder, the piston movements being caused by a movable cam whose position determines the volume dispensed each piston stroke. The position of the cam is controlled in accordance with different parameters, but at any time it is considered to check the weight of product distributed so that the weight can vary depending on the density of the dispensed product.

EP-A-52 546 discloses a weight metering device wherein the product to be dispensed is disposed in a hopper and flows at the opening of a filling spout. Such a device is not suitable for filling containers at a high rate with a high viscosity product.

An object of the present invention is to provide a method and a container filling apparatus that achieve a high rate while maintaining a high accuracy regardless of product viscosity to be dispensed.

In view of achieving this purpose, the invention provides a container filling process in an installation comprising a rotary carousel element with several filling stations each comprising a volumetric dispenser of the type comprising a piston-cylinder assembly in wherein the piston defines the volume of material transferred, this method comprising the steps of successively and individually introducing receptacles on a filling station while simultaneously filling the volumetric dispenser, then filling each receptacle from the volumetric dispenser by means of a control member (such a process is known from US-a-2961013), characterized in that it further comprises the steps of:<ul><li>- Weigh at least one container with one of the filling stations while the receptacle is still empty,</li><li>- Weigh continuously weighed empty container during filling of the container and compare the net weight of product introduced to a set value,</li><li>- Act on the control member depending on the result of this comparison to modify the volume transferred by the volumetric dispenser at all filling stations.</li></ul>

According to the invention there is also provided a container filling apparatus comprising: a rotary carrousel, means to introduce receptacles one by one on a plurality of filling stations each comprising a volumetric dispenser of the type comprising a piston cylinder wherein the piston defines the volume of product transferred, means for filling the volumetric feeder with the product then empty it into a container, the transferred volume is determined by a controller (such an installation is known from US- a-2961013), wherein at least one filling station includes a balance associated with a computing unit and memory storage to store the weight of an empty container on the scale introduced, weight full container given by each scale to calculate the net weight of the product introduced into the container, and means to act on the controller to change the volume of product to be introduced in the containers with the upstream carousel weighed container.

Other features and advantages of the present invention appear better on reading the following description in conjunction with the accompanying drawings in which:<ul><li>- Figure 1 is a plan view dessusschémati- that a filling installation comprising a rotary carrousel type member, which have been shown the different stages of progression of a container on a filling station equipped with a balance,</li><li>- Figure 2 is a schematic sectional view of an embodiment of a filling station,</li><li>- Figure 3 is a schematic sectional view along line II-II of the embodiment of a filling station shown in Figure 2, the feed hopper and the volumetric metering device not being shown, and</li><li>- Figure 4 is a schematic developed view of a cam and two filling heads, one on the left being shown on the rising ramp of the cam, the right on the falling ramp of the cam.</li></ul>

In Figure 1 are shown the different stages of the path of a container placed on one of the filling stations equipped with a balance of a filling arrangement in the chain comprising a rotating carousel 3. The container is supplied by a 1 conveying means to a dispensing star 2 who introduced the item 6 on one of the filling stations of the carousel 3 equipped with a scale. The carousel 3 is driven with a rotational movement. Between the point 6 and point 7 empty container is weighed and its weight is stored while completes filling the volumetric dosing of the filling station, started at point 40. Between point 7 and point 8 and between item 8 and item 9, the volume of product contained in the volumetric feeder is transferred with a fast flow (7-8) and then with a slower (8-9) of the dispenser into the container. The container is weighed continuously between entering the carousel and its exit from the carousel. Between point 9 and point 10 the balance stabilizes and determines the weight of the full container. A member of calculation and control, a microprocessor for example, calculated from the weight of the full container and the weight of the empty container previously stored the exact weight of product introduced into the container, compares this weight to a desired value and optionally control the modification of the assay that will contribute containers occurring at a later stage. The advantage of mobility or balance (s) installed (s) of the carousel is to allow a sufficiently long load time to be precise, without slowing down the filling rate. Once filled the container leaves the carousel 3 or point 10, tangentially to the carousel 3, on a conveyor means 25 or in paragraph 40, according to a préférencielle direction parallel to the conveyor means 1 for example, by via a distribution star 4.

2 shows a schematic sectional view of an embodiment of a filling station equipped with a scale. Each filling station is located on the rotating carousel 3 and comprises: an electronic balance 36; 38 means pure center a container 39; a feed hopper of the product 22 to be packaged 12; a volumetric metering device 37 having a piston 28 provided with sealing means 29, a cylinder 13 in which slides the piston 28, a rod 33 pushing the piston 28; a distributor 14 comprising a body 19 and a cylindrical plug 18 pivotable in the body 19.

The body 19 has a horizontal axis of bore 27; a vertical duct 24 located in its upper part and opening out firstly into the hopper 12 and on the other hand in the pin bore 27; a vertical duct 26 located in its upper part and opening out firstly in the volumetric metering device 37 and on the other hand in the pin bore 27; a vertical bore coaxial with the duct 26, overcoming the latter and receiving the cylinder 13 of the volumetric metering device 37; a vertical duct 30 located in its bottom and opening out firstly into the bore axis 27 and the other above the container 39.

The cylindrical valve 18 occupies the vertical axis of bore 27 of the body 19 in which it can rotate. It has a recess 15 which, in a specific position of the plug 18 relative to body 19, communicates the conduits 24 and 26 of body 19; a cylindrical duct 17, without communicating with the recess 15, which, in another predetermined position of the plug 18 relative to the body 19, communicates the conduits 26 and 30 of the body 19; a control lever 20, to rotate the plug 18 within the body 19. Electrical, pneumatic or the like, not shown in the figure, acts on the control lever 20 of the instructions that notify them of the member of calculation and control.

When a filling station is located between the points 10 and 7 the path shown in Figure 1, the plug 18 is positioned so that the recess 15 is opposite the ducts 24 and 26 of the body 19 and the hopper of supply 12 and the volumetric feeder 37 are in communication (as in Figure 2). When a filling station is located between the point 7 and point 9 of the path shown in Figure 1, plug 18 is positioned so that the conduit 17 is opposite conduits 26 and 30 of the body 19 and the volumetric feeder 37 and the container 39 are in communication.

4 shows a schematic developed view of a cam controlling the operation of two filling stations. We must conceive that in reality such a cam is not in a plane but is wrapped on a cylinder of the same center as the carousel and it controls a number of filling stations, variable depending on the case, but much greater than 2.

The cam 34 shown in Figure 2 has a rising ramp to two successive inclinations: ramp 340 between points 40 and 6, adjustable ramp 341, between points 6 and 7; a ramp down to two inclinations: ramp 342 between points 7 and 8, ramp 343 between points 8 and 9; a horizontal portion 344 between the points 9 and 40. A against cam 35, parallel to the cam 34, is disposed above the descending ramp of the cam 34, between the points 7 and 9. (The numbering of these points corresponds to that of Figure 1). The rising ramp corresponds to the filling of the volumetric metering device 37, which in this embodiment is a metering roller. The ramp down to two inclinations is the transfer of the product to two flow speeds, the volumetric feeder 37 into the container 39.

The cam 34 and against the cam 35 are fixed with respect to the rotary carousel 3 on which are installed the filling stations. The cam 34 only the roller guide 32 secured to the rod 33 of the piston 28 between point 40 and point 7. Between point 7 and point 9, that is to say, the down ramp of the cam 34, the cam 34 engages the cam follower 35 against the roller 32 for guiding.

The cam 34 has a rising ramp portion 341 whose inclination is variable and is controlled by the stroke of a worm 16 driven by a gear motor 25. If the organ of calculation and control is a difference between the weight of product introduced into the container and the set value, it controls the change of the inclination of the ramp portion 341 upwardly or downwardly depending on the direction of drift. The volume change allowed in the volumetric metering device resulting naturally occurs for containers occurring at a later stage.

The advantage of such a device, with which the verification of the amount of product is introduced into the containers since a statistical fraction of the number of carousel filling stations is equipped with a scale, is the detection and correcting a possible drift of the assay, regardless of the cause.