EP1987283B1

EP1987283B1 - A filling system for filling substance into containers

Info

Publication number: EP1987283B1
Application number: EP07702475.0A
Authority: EP
Inventors: Erik Jensen
Original assignee: Kosan Crisplant AS
Current assignee: Kosan Crisplant AS
Priority date: 2006-02-10
Filing date: 2007-02-06
Publication date: 2019-04-10
Anticipated expiration: 2027-02-06
Also published as: CN101379340A; JP4886795B2; SA07280033B1; BRPI0707624A2; WO2007090398A1; PL1987283T3; TR201910234T4; CN101379340B; BRPI0707624B8; EP1987283A1; ES2733019T3; MY149213A; BRPI0707624B1; EA014677B1; EA200801803A1; JP2009525926A

Description

The present invention relates to a filling system for filling substance into containers. The invention further relates to a method of operating such filling system.
Filling of containers with one or more substances is a common task of packaging substance e.g. for transportation or storage purposes. Within the field of filling containers with gas, such as liquid petroleum gas - also known as LPG, filling turntables and carrousels are often used. Containers are conveyed and transferred to the turntable or carrousel, where they are received by filling units and each continuously weighed on an electronic scale. The scales are connected to a control system, which controls filling of the containers in response to signals from the scales, the signals being proportional to the amount of substance filled into the containers. This type of filling is used for filling several hundreds or even thousands of containers per hour with LPG. To obtain such high filling high capacity the turntables or carrousels are equipped with multiple, normally at least a dozen, filling units, each having a scale included, for filling many containers at a time and it is performed in a cycle where containers are received in a first position, filled during rotation of the turntables or carrousels to bring the filled containers to a second position where they are unloaded. Although this known method of filling containers functions very well, it does, however, require a large number of scales and corresponding control equipment. A system of this type is e.g. known from WO 9939130 A2 .
EP 0661493 discloses an LP gas charging equipment having an electro balance 3 disposed in a carrying-in line 1 to a turntable A to weigh containers, a control panel B to which the electro balance is connected and which has a central processing unit, gas charging valves adapted to open while the containers are moved by the turntable to supply gas from a gas distributor 5 to the containers, and flow meters 9 for measuring the flow rate of gas at the time of gas charging, the amount of gas to be charged being calculated by the central processing unit B on the basis of the measured value provided from the electro balance to control the gas charging work, an air distributor 6 and an electric distributor 7 are disposed centrally on the turntable, solenoid valves 15 and controllers 33 are arranged around those distributors.
EP 0534876 discloses a method and an installation for filling liquefied-gas bottles 3 and checking the weight of the said bottles after filling, comprising a weighing unit 13, bottles 3 located upstream of a carrousel 2 and a programmable automatic machine 15 connected to the said weighing unit 13 and to the said carrousel 2 and making it possible to determine the weight of gas in order to fill each weighed bottle 3 according to the reference values stored in the memory of the said programmable automatic machine 15 to control through the said automatic machine the valve for filling this bottle 3 which has reached one of the filling stations 2a of the carrousel 2; after filling, the filled bottle 31 is weighed and the weight of gas delivered during the filling of the bottle 3 is corrected through the said programmable automatic machine 15.
FR 2670864 discloses a plurality of supports 1 capable of receiving a cartridge C, said supports 1 being mounted on a transfer member 2 so as to be moved and positioned in succession facing the various stations, namely: - a station for weighing the empty cartridge 3, - a station for positioning the shutoff means 4, - at least one station T for filling the cartridge C with gas in the liquid state, - a station 17 for weighing and checking the full cartridge, the whole of the installation being slaved by a programmable automaton.
One object of the invention is to provide a filling system with a reduced number of scales included as well as a corresponding method of operating such system. Another object is to provide a filling system having at least a capacity which is equal to the known type of filling systems as well as a method of operating the system to obtain such capacity. Other objects appear from the description, the claims and the enclosed figures.
A first aspect of the invention involves a filling system as defined by claim 1.
The weighing information obtained while passing the weighing sections provides sufficient information in order to, within an acceptable tolerance, predict when a predetermined amount of substance has been filled into a container. Accordingly, the filling system, according to the invention, may include only two scales, i.e. one for each of the at least two weighing sections, although there may be any number of transport units. This is significantly less than the known systems, which include a scale for each transport unit and thereby normally at least twelve scales for a system having twelve transport units. The filling system, according to the invention, may include any number of transport units, such as from 6 to 36, such as 6, 12, 24, or 36, or any other number in between the mentioned numbers or a higher number, and be operated using two scales only. Additional scales may be used for increasing precision, performing further operations, checking weighing etc.
The scales are incorporated in separate weighing sections of the track, said sections being placed with a distance in the direction of the track. The weighing sections are arranged to weigh the transport units individually, including any present containers and substance, while the transport units are passing the weighing sections. Information, with regard to the amount of filled substance in at least two instances in the filling sequence, may hereby be obtained. This weighing information forms a basis for operating the filling system, such as enabling calculation of a total filling time, which is necessary for appropriately filling the containers, as well as operating the filling means accordingly. The features of the filling system, according to the invention, may be implemented in a carrousel or turntable system whereby the filling capacity, i.e. the number of containers which may be filled per time unit, may correspond to the capacities of the known systems.
The track may be circular and the filling system implemented as a carrousel, or it may be oval or having a polygon-like shape, where the transport units are transported in a loop, and where filling may take place during most of the loop. Or the part of the track where filling takes place may have any shape. This may include a linear part where the containers are transported in one linear direction only. The track may be elevated e.g. to an overhead position where the transport units are hanging downwards from the track. Also, the transport units and the filling means may be integrated. This may include an embodiment where the containers are engaged only at their filling opening, e.g. a bottleneck, by the transport units/fillings means and are transported also in that way at least during the filling operation.
A preferred embodiment of the filling system involves placing at least two weighing sections in positions downstream of a position of the track where filling is to be started and upstream of a position where filling is to be completed. The term "downstream" indicates a position positioned in the direction in which the transport units are moved and the term "upstream" indicates a position positioned in a direction which is opposite to the direction in which the transport units are moved. A first weighing section placed after a position of the track where filling is to be started may provide a first indication of an amount filled into the container, which amount may be used to calculate a filling rate, i.e. the amount of substance filled per time unit. The filling rate may then be used to calculate the filling time for reaching a first predetermined filling level. A second weighing section placed before a position where filling is to be completed may provide a second indication of an amount filled into the container, e.g. to check whether the first predetermined level has been obtained, and/or to calculate the filling rate again based on a longer time period than the first calculated filling rate. The second indication of filled amount may also be used to calculate a remaining amount still to be filled into the container as well as a remaining filling time for a top-up filling operation.
Another preferred embodiment of the system includes that at least one weighing section is placed in a position downstream of a position of the track where filled containers are unloaded from the transport units and a position upstream of a position where containers to be filled are received by the transport units. Such a weighing section may be used to obtain a tare weight of the transport unit. Any spilled substance or other generally undesired matter randomly present on the transport unit would otherwise compromise the precision of the filling operation, e.g. lead to filling less substance into the container than intended.
A further preferred embodiment of the system includes that at least one weighing section is placed in a position downstream of a position of the track where containers to be filled are received by the transport units and upstream of a position where filling is to be started. Such weighing section may be used to obtain a tare weight of the transport unit including a container.
A yet further preferred embodiment of the filling system includes that at least one weighing section is placed in a position downstream of a position of the track where filling is to be completed and upstream of a position where filled containers are unloaded from the transport units. Such weighing section may be used to check the weight of the transport unit, the container and the substance filled into the container. When the tare weight of the transport unit and the container is known, this may provide information regarding the amount of substance which has actually been filled into the container, such that e.g. the filled amount may be checked against a desired amount, an acceptance interval, a maximum amount, a minimum amount, etc.
Another preferred embodiment of the filling system includes that at least one wheel or roller is arranged between each transport unit and the track to provide movable support for the transport unit. Alternatively, at least one sliding shoe may be arranged in a similar manner. This provides a suitable direct contact between the transport unit via the wheel, roller or sliding shoe to the track, and hence also to the weighing sections incorporated in the track. One wheel is preferred, because it provides opportunity to weigh the transport unit etc. over the entire length of the weighing section and hence provide maximum time for performing the weighing operation. This is advantageous since the length of the weighing section must be less than the width of a transport unit, here the centre to centre distance between the wheels of two adjacent transport units, since only one transport unit may be present on the weighing section at a time to perform an individual weighing. This highly increases the capacity of the filling system, since the transport units may be moved fast and the weighing operations still be made with sufficient precision.
A further preferred embodiment of the filling system includes that the track is made in sections made from rails or rail-like metal profiles. Rails and metal profiles provide a solid, durable structure at a reasonable cost.
An additional preferred embodiment of the filling system includes each transport unit having at least two supporting arms, said supporting arms being hinged to the transport units in one end and hinged to a central section of the driving means in an opposite end, where each transport unit, a set of two arms and said central section are arranged to structurally form a parallelogram which supports said transport unit. The two supporting arms hinged to the transport unit and arranged to form a parallelogram in combination with the other components provide the function that when the container carrying part of the transport unit is horizontal when the transport unit is installed, then it is kept horizontal at all times despite any minor variations in the track, such as a small deviation from a common horizontal plane of the track. If the container carrying part of the transport unit is not horizontal, load from the container will be introduced in the supporting arms, whereby the full load is not transferred to the weighing sections. This is avoided by the parallelogram and the precision in the weighing is maintained.
The filling system according to the invention may be used for any substance, e.g. a powder, a gas, a fluid or a liquid, or a combination of such substances, or it could be granules, or a plurality of pieces of different size, even larger pieces e.g. vegetables such as carrots, potatoes, etc. A preferred use of the system is for filling containers with a liquefied gas, in particular a liquid petroleum gas (LPG).
Some or all of the aforementioned embodiments of the filling system according to the invention may be combined and included in one filling system.
Another aspect of the invention relates to a method of operating a filling system for filling substance into containers, where operation of the filling system for filling a container includes steps of: providing a filling system according to any of claims 1-9 and

a) having a transport unit receive a container,
b) starting filling of substance into the container and registering the start time of filling,
c) continuing filling for a predetermined time period t1,
d) while the transport unit is passing a first weighing section of the track, weighing a total mass of the transport unit, the container and the substance filled into the container,
e) calculating an amount of substance A1 filled during time period t1 by subtracting previously determined masses of the transport unit and the container from the total mass obtained in step d),
f) calculating a filling rate during time period t1,
g) calculating a remaining filling time t2 based on the calculated filling rate during time period t1 for reaching a first predetermined filled amount A2,
h) continuing filling in the calculated time period t2,
i) while the transport unit is passing a second weighing section of the track, weighing a total mass of the transport unit, the container and substance filled into the container,
j) calculating an amount of substance A2 filled during time period t2 by subtracting previously determined masses of the transport unit, the container and previously filled amount of substance A1 from the total mass obtained in step i),
k) calculating a filling rate during time period t2,
l)calculating a remaining filling time t3 based on the calculated filling rate during time period t2 for reaching a second predetermined filled amount A3,
m) continuing filling in the calculated time period t3.

By this method the filling system may be operated on the basis of input from only two scales. By operating the filling for reaching a first predetermined amount first and thereafter filling to reach the second predetermined amount, the risk that too much or too little substance is filled into the container is reduced, i.e. a high degree of precision is obtained in the filling although only two scales are used. Filling may be continued or discontinued while weighing is performed, i.e. there may be or may not be a delay between the time periods t2 and t1 as well as t3 and t2.
A further operation of the filling system includes that steps a) - m) are followed by steps of:

n) while the transport unit is passing a further weighing section N of the track, weighing a total mass of the transport unit, the container and the substance filled into the container,
o) calculating an amount of substance A(N-1) filled during a previous time period t(N-1) by subtracting previously determined masses of the transport unit, the container and a preceding amount of substance A(N-2), which was filled into the container in a time period t(N-2) prior to said previous time period t(N-1), from the total mass obtained in step n),
p) calculating a filling rate during said previous time period t(N-1),
q) calculating a remaining filling time period t(N) based on the calculated filling rate during said previous time period t(N-1) for reaching a further predetermined filled amount A(N),
r) continuing filling during the calculated remaining time period t(N), and
s) while the filled amount is less than a predetermined final amount, repeating steps n) - r) until said final amount is obtained.

By employing a further weighing section, which means that three or more scales are used, it is possible to obtain a higher degree of precision of the filling. By using more scales the filling process may be divided into multiple sequences, each used for successively reaching a higher and higher filled amount. In this way the filling may be performed gradually in order to reach the final amount with a very high degree of precision.
A preferred operation of the filling system includes that steps a) - k) or steps n) - s) are followed by steps of:

while the transport unit is passing a weighing section of the track, weighing a total mass of the transport unit, the container and the filled substance, and
calculating the total amount of substance present in the container by subtracting previously determined tare masses of the transport unit and the container from the total mass.

In this way the total amount filled is found and may then be compared with a predetermined minimum amount, maximum amount, etc.
Another preferred operation of the filling system includes that a ratio of the predetermined amounts A2 and A3 defined as (A3-A2)/A3 is less than 0.25, preferably less than 0.1 and more preferred between 0.001 and 0.1. In this way the first predetermined amount A2 is quite close to the second predetermined amount A3, whereby filling until the amount A2 is reached is a top-up filling. Reaching A2 may bring the filling close to a desired end amount, and a small top-up amount is calculated and filled which provides a precise method of reaching said desired end amount.
A further preferred operation of the filling system includes, while the transport unit is passing a weighing section of the track, a prior step of weighing the transport unit to obtain a tare mass of the transport unit. Any spilled substance or other generally undesired matter randomly present on the transport unit may hereby be compensated for in the filling operation.
A yet further preferred operation of the filling system includes, between steps a) and b), intermediate steps of:

while the transport unit is passing a weighing section of the track, weighing a total mass of the transport unit and a received container, and
calculating a potential amount of residual substance present in the container by subtracting previously determined tare masses of the transport unit and the container from the total mass.

The filling may hereby be compensated according to the calculated residual substance, which is often present when refilling containers for LPG and other gasses, wherein the residual substance may be of an acceptable quality.
The invention is described in further details below and with reference to the appended figures. The figures display examples of embodiments of the invention and are included for informative purposes only.

Figure 1 shows a layout of a filling system according the invention as seen from above, where means for loading and unloading of containers are included. The arrow R indicates the direction of movement.
Figure 2 shows a side view of a transport unit, a container and filling means.
Figure 3 shows a front view of a transport unit, a container and filling means.
Figure 4 shows a system according to the invention displayed without transport units and having a track including two weighing sections placed between a position where filling is to be started and a position where filling is to be completed.
Figure 5 shows a system as in Fig. 4 where the system is including five weighing sections.

Fig. 1 shows elements of a filling system for filling substance into containers 1. Containers 1 are forwarded by a conveyor 14 to a position 9, where containers 1 to be filled are received by a plurality of transport units 2, each being arranged to receive and transport at least one container. Filling of the substance is performed while the transport units 2 are moved in the direction R indicated by an arrow towards a position 8 where the filled containers 1 are unloaded to the conveyor 14. A substance distribution system comprising filling means 3 is arranged relative to the transport units 2 for filling substance into the containers 1, while being transported by the transport units 2, cf. Fig. 2 and 3. Referring again to Fig. 1, driving means 4 are arranged to provide movement, here rotation, of the transport units 2, here shown as a central section 12 arranged at the rotation centre. The driving means 4, 12 are connected to the transport units by supporting arms 11. As fig. 1 shows the system from above, a substantially horizontal and circular track 5 along which the transport units 2 are moved while being driven by the driving means 4 is only visible on fig. 1 between the transport units. The track 5 is provided to support said transport units. Further details of the track 5 are shown in the other figures. A control system for controlling operation of the filling system is not shown. Specific details regarding the substance distribution system, the filling means, the control system and the drive means for e.g. filling LPG gas are well known to the skilled person. The invention may, however, also be employed in other applications.
Figs. 2 and 3 display a container 1 supported by a container carrying part of a transport unit 1 and filling means 3 provided for filling a substance into the container 1. A wheel is arranged between the transport unit 2 and the track 5 to provide a movable support 10 for the transport unit such that the weight of the transport unit 2, the container 1, the filling means 3 and any present substance is supported largely by the support 10 and transmitted directly to the track 5 and from there to an electronic scale 6 (figs. 4 and 5) comprising a weighing cell 16. Two or more wheels or a sliding shoe or rollers or any other similar means may be used as movable support 10. Fig. 2 shows that two supporting arms 11 are hinged with hinges 15 to the transport unit 2 in one end and hinged to a central section 12 of the driving means in an opposite end, whereby the transport unit 2, a set of two arms 11 and the central section 12 structurally form a parallelogram which supports the transport unit 2.
Fig. 4 and 5 display the filling system without transport units 2 and filling means 3 for showing information regarding the electronic scales 6 and weighing sections 7 of the track 5. Containers 1 are transported to the filling site by a conveyor 14 and enter at a position 9 and exit at a position 8. The electronic scales 6 are in Fig. 4 incorporated in two separate sections of the track to provide individual weighing sections 7a and 7b, which are distributed along the track 5. Each electronic scale 6 preferably comprises one or more electronic weighing cells 16, depending on the size and dimensions of the weighing section. The weighing sections 7a and 7b are arranged to weigh the transport units 2 individually, including any present containers and substance, while the transport units 2 are passing the weighing sections 7a and 7b while being moved by the driving means 4, 12. The operation of the filling system includes operations in relation to weighing information obtained from the weighing sections 7a and 7b. A transport unit will first pass a first weighing section 7a where the weight of a transport unit is determined individually, including any present containers and substance, while the transport unit 2 is passing said first section 7a. A while later the transport unit will pass the second weighing section 7b, where another weight determination is performed. From the two individual weighings it may e.g. be calculated how much the total weight has increased between the two weighings, whereby an indication is obtained with respect to an amount of substance filled between the two weighings.
In Fig. 5 the system involves five scales 6 and five individual weighing sections 7a-7e, which are incorporated in separate sections of the track 5 to provide individual weighing sections distributed along the track 5. This displayed system in fig. 5 is preferably adapted for filling LPG gas in recycled gas bottles. Each electronic scale 6 preferably comprises one or more electronic weighing cells 16, depending on the size and dimensions of the weighing section. The weighing sections 7a - 7e are arranged to weigh the transport units 2 individually, including any present containers and substance, while the transport units 2 are passing the weighing sections, while being moved by the driving means 4, 12. The operation of the filling system includes operations in relation to weighing information obtained from the weighing sections 7a - 7e. A transport unit 2 at a position 9 receives a container 1 to be filled. Before the container 1 is received, the tare weight of the empty transport unit 2 is determined at a weighing section 7e. This is done after a filled container has been unloaded at an exit position 8. The transport unit 2 will then pass a weighing section 7a, where the weight of the transport unit 2 and the container 1 is determined, including any residual substance present in the container, while the transport unit 2 is passing said section 7a. At a previous occasion the individual tare weights of the containers have been determined and the information is stored in the control system controlling the filling operation. The weight obtained at section 7a is compared with the stored information regarding the tare weight of the container 1 and the tare weight of the transport unit 2 determined at section 7e in order to calculate the presence and amount of any residual substance in the container 1. This information is used to determine how much substance is needed to fill the container to a predetermined level. Filling is now started and the starting time is registered. A while later the transport unit 2 passes weighing section 7b, where a weight determination is performed and the time passed since filling began is registered. A flow rate of the filling is determined from the filling time and the amount filled. This is used to extrapolate necessary filling time to obtain a first filling level to be reached before a further weighing is performed at section 7c. Filling is started again and the starting time is noted. When the extrapolated filling time runs out, the filling is stopped. The total weight is determined at section 7c, where a flow rate is determined for the filling performed between section 7b and 7c. The amount of substance filled up to this point is compared to a predetermined second filling level and a second calculation in the form of an extrapolation is made to determine a necessary filling time for reaching the second filling level based on the flow rate. Filling is started again and the starting time is noted. When the second extrapolated filling time runs out, the filling is stopped. The total weight is checked at section 7d to verify that the amount of substance present in the container is within a predetermined tolerance interval. If not, a further preferably short filling may additionally be performed before unloading, or the container 1 may be given an extra filling cycle by passing sections 7e and 7a-7d again to obtain a correct amount of substance. In the latter event, no tare weight is obtained in section 7e, since this was already obtained previously. The filled container 1 is unloaded at position 9, and the transport unit 2 is ready to receive a new container after its tare weight has been obtained at section 7e.

Example 1:

In a filling system according to the invention including five weighing sections the following steps are performed to fill 8,000 g (8 kg) of LPG into a gas bottle:

a transport unit is weighed at a first weighing section and its tare mass of 40,000 g is obtained,
a container having a known tare mass of 560 g is received by the transport unit,
the transport unit and the container are weighed together on a second weighing section and have a total mass of 40,570 g,
10 g of residual LPG is calculated (residual amount = total mass minus tare mass of the transport unit minus tare mass of the container = 40,570 g - 40,000 g - 560 g = 10 g),
filling with LPG is started and continued for a first time period of 3 seconds,
the transport unit, the container and the LPG content are weighed together on a third weighing section and have a total mass of 42,050 g,
the amount of LPG is now 42,050 g - 40,000 g - 560 g = 1,490 g,
the filling rate in the first time period is calculated to be (1,490 g - 10 g) / 3 seconds = 493.3 g/second,
a second time period for reaching 7,300 g of LPG, thereby leaving 700 g for a top-up filling, is calculated to be (7,300 g - 1,490 g) / 493.3 g/second = 11.777 seconds,
filling is continued in the second time period for 11.777 seconds,
the transport unit, the container and the LPG content are weighed together on a fourth weighing section and have a total mass of 47,899 g,
the amount of LPG is now 47,899 g - 40,000 g - 560 g = 7,339 g,
the filling rate in the second time period is calculated to be (7,339 g - 1,490 g) / 11.777 seconds = 496.6 g/second,
a third time period for reaching 8,000 g of LPG is calculated to be (8,000 g - 7,339 g) / 496.6 g/second = 1.331 seconds,
filling is continued in the third time period for 1.331 seconds,
the transport unit, the container and the LPG content are weighed together on a fifth weighing section and have a total mass of 48,549 g,
the amount of LPG is now 48,549 g - 40,000 g - 560 g = 7,989 g, which is 11 g below the target net LPG weight of 8,000 g.

It is to be understood that the invention as disclosed in the description and in the figures may be modified and changed and still be within the scope of the invention as claimed hereinafter.

Claims

A filling system for filling substance into containers (1), said system comprising:
- a plurality of transport units (2), each being arranged to receive and transport at least one container (1),

- a substance distribution system comprising filling means (3) arranged relative to the transport units for filling substance into at least one container,

- driving means (4) arranged to move the transport units (2),

- a track (5) along which the transport units (2) are moved by the driving means (4), said track (5) being provided to support said transport units (2) while being moved,

- a control system for controlling operation of the filling system, and
at least one electronic scale (6) incorporated in each of at least two separate and substantially horizontal sections of the track (5), where said sections are adapted to provide individual weighing sections distributed in the track (7), characterized in that the filling means which are arranged for filling substance into at least one container are configured to do it while said at least one container is transported by a transport unit, at least one wheel or roller or at least one sliding shoe is arranged between each transport unit (2) and the track (5) to provide movable support for the transport unit (2), such that the weight of the transport unit (2), the container (1), the filling means (3) and any present substance is supported largely by the moveable support and transmitted directly to the track (5) and from there to the electronic scale (6) comprising a weighing cell (16), and
said weighing sections are arranged to weigh the transport units (2) individually, including any present containers and substance, while the transport units (2) are passing the weighing sections (7) when being moved by the driving means (4), and where operation of the filling system includes operations in relation to weighing information obtained from the weighing sections (7).
A filling system according to claim 1, where at least two weighing sections are placed in positions downstream of a position of the track (5) where filling is to be started and upstream of a position where filling is to be completed.
A filling system according to claim 1 or 2, where at least one weighing section is placed in a position downstream of a position of the track (5) where filled containers are unloaded from the transport units (2) and upstream of a position where containers to be filled are received by the transport units (2).
A filling system according to any of the preceding claims, where at least one weighing section (7) is placed in a position downstream of a position of the track (5) where containers to be filled are received by the transport units (2) and upstream of a position where filling is to be started.
A filling system according to any of the preceding claims, where at least one weighing section (7) is placed in a position downstream of a position of the track (5) where filling is to be completed and upstream of a position where filled containers are unloaded from the transport units (2).
A filling system according to any of the preceding claims, where the track (5) is made in sections made from rails or rail-like metal profiles.
A filling system according to any of the preceding claims, where each transport unit (2) includes at least two supporting arms (11), said supporting arms (11) being hinged to the transport units (2) in one end and hinged to a central section (12) of the driving means in an opposite end, where each transport unit (2), a set of two arms and said central section (12) are arranged to structurally form a parallelogram which supports said transport unit (2).
A filling system according to any of the preceding claims, where the substance is a powder, a gas, a fluid or a liquid, or a combination of such substances.
A filling system according to claim 8, where the substance is a liquefied gas, in particular a liquid petroleum gas (LPG).
A method of operating a filling system for filling substance into containers (1) according to any of claims 1-9, where operation of the filling system for filling a container includes characterizing steps of:
providing a filling system according to any of claims 1-9, and
a) having a transport unit (2) receive a container (1),

b) starting filling of substance into the container (1) and registering the start time of filling,

c) continuing filling for a predetermined time period t1,

d) while the transport unit (2) is passing a first weighing section (7) of the track (5), weighing a total mass of the transport unit (2), the container (1) and the substance filled into the container (1) via a moveable support (10),

e) calculating an amount of substance A1 filled during time period t1 by subtracting previously determined masses of the transport unit (2) and the container (1) from the total mass obtained in step d),

f) calculating a filling rate during time period t1,

g) calculating a remaining filling time t2 based on the calculated filling rate during time period t1 for reaching a first predetermined filled amount A2,

h) continuing filling in the calculated time period t2,

i) while the transport unit (2) is passing a second weighing section (7) of the track (5), weighing a total mass of the transport unit (2), the container (1) and the substance filled into the container (2) via the moveable support (10),

j) calculating an amount of substance A2 filled during time period t2 by subtracting previously determined masses of the transport unit (2), the container (1) and previously filled amount of substance A1 from the total mass obtained in step i),

k) calculating a filling rate during time period t2,

l) calculating a remaining filling time t3 based on the calculated filling rate during time period t2 for reaching a second predetermined filled amount A3,

m) continuing filling in the calculated time period t3.
A method according to claim 10, where steps a) - m) are followed by steps of:
n) while the transport unit (2) is passing a further weighing section N of the track (5), weighing a total mass of the transport unit (2), the container (1) and the substance filled into the container (1),

o) calculating an amount of substance A(N-1) filled during a previous time period t(N-1) by subtracting previously determined masses of the transport unit (2), the container (2) and a preceding amount of substance A(N-2), which was filled into the container (1) in a time period t(N-2) prior to said previous time period t(N-1), from the total mass obtained in step n),

p) calculating a filling rate during said previous time period t(N-1),

q) calculating a remaining filling time period t(N) based on the calculated filling rate during said previous time period t(N-1) for reaching a further predetermined filled amount A(N),

r) continuing filling during the calculated remaining time period t(N), and

s) while the filled amount is less than a predetermined final amount, repeating steps n) - r) until said final amount is obtained.
A method where operation of the filling system according to steps a) - k) of claim 10 or steps n) - s) of claim 11 are followed by steps of:
- while the transport unit (2) is passing a weighing section (7) of the track (5), weighing a total mass of the transport unit (2), the container (1) and the filled substance, and

- calculating the total amount of substance present in the container (1) by subtracting previously determined tare masses of the transport unit (2) and the container (1) from the total mass.
A method according to any of claims 10-12, where a ratio of the predetermined amounts A2 and A3 defined as (A3-A2)/A3 is less than 0.25, preferably less than 0.1 and more preferred between 0.001 and 0.1.
A method according to any of claims 10-13, where operation of the filling system includes, while the transport unit (2) is passing a weighing section (7) of the track (5), a prior step of weighing the transport unit (2) to obtain a tare mass of the transport unit (2).
A method according to any of claims 10-14, where operation of the filling system includes, between steps a) and b) of claim 10, intermediate steps of:
- while the transport unit (2) is passing a weighing section (7) of the track (5), weighing a total mass of the transport unit (2) and a received container (1), and

- calculating a potential amount of residual substance present in the container (1) by subtracting previously determined tare masses of the transport unit (2) and the container (1) from the total mass.