FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Capsule filling machine for dosing capsules with dry powder
APPLICANTS
Sci-tech Centre. 7 Prabhat Nagar, Jogeshwari West, Mumbai 400 102, Maharashtra, India, an Indian company
INVENTORS
Singh Jasjit, a British subject and Deshmukh Prakash and D'Silva James, both Indian nationals and all of Sci-tech Centre, 7 Prabhat Nagar, Jogeshwari West, Mumbai 400 102. Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed :

FIELD OF THE INVENTION
This invention relates to a capsule filling machine for dosing capsules with dry
powder.
Capsule filling machines are generally used to fill dry particulate pharmaceutical or neutraceutical material such as powders, pellets or microtablets in hard gelatin capsules and to make dosage forms of the pharmaceutical or neutraceutical material. Dosage forms of the particulate pharmaceutical or neutraceutical material encapsulated in capsules are easy and convenient to be taken orally. It is also easy and convenient to maintain accuracy and consistency of the dosages by volumetric filling of the pharmaceutical or neutraceutical material in capsules.
Highly active dry medicinal powder products such as those for inhalation are very expensive and are required in microdoses of the order of 2 - 30 milligrams. Microdoses of such products in capsules are formed by volumetric filling of the capsules with very small quantities of the products very precisely and accurately. Capsule filling machines used for microdosing are to be very precise and accurate in filling the capsules volumetrically. Furthermore, the powder should be well dispersed and loosely distributed without being agglomerated in order to ensure that the entire dosage is available to the user effectively and easily.
BACKGROUND OF THE INVENTION
Amongst the various designs of capsule filling machines that are known and available, one apparatus for metering and discharging measured quantity of dry particulate material comprises a container for feeding the material and an elongated

metering member slidably supported in the container on a supporting member and provided with one or more metering chambers transversely extending through the elongated metering member. The metering member with the metering chambers is movable to a filling position to receive the particulate material in the container and to an ejection position to discharge the particulate material. The apparatus also comprises an air driven vibrator for the container and means for delivering pulses of air at the upper ends of the metering chambers positioned at the ejection position to discharge the dosages in the metering chambers into capsules being formed underneath the supporting member (British Patent No 1089747).
In the above apparatus the metering member with the metering chambers filled with the particulate material are slid along the supporting member between the filling position and ejection position in order to discharge the dosages from the metering chambers. During the sliding movement of the metering chambers against the supporting member, there are chances for the particulate material in the metering chambers to get crushed and damaged between the bottom ends of the metering chambers and the supporting member. This will cause not only loss of valuable material and dust generation but will also reduce the dissolution properties of coated material. It may also cause weight variations and dosage variations of the filled capsules. The particulate material may also clog the clearance between the metering chambers and supporting member and obstruct the smooth sliding movement of the metering chambers against the supporting member.
In another design, an apparatus for volumetric metering of small quantities of a product such as medicinal powder or granules and dispensing them into hard gelatin

capsules, comprises a metering disc that revolves around a vertical axis intermittently and that has metering chambers as narrow and through bores provided in groups and distributed uniformly over a pitch circle. The metering chambers are open at the top and bottom thereof and are closable at the bottom by curved pushers provided with apertures coinciding with the metering chambers. The curved pushers are circumferentially displaceably supported to the underside of the metering disc coaxially with the metering disc between two bearing rings which are secured coaxially with the metering disc. The curved pushers are held spring tensioned to pull the pushers into closing position and close the metering chambers in the filling position of the metering disc and retain the product in the metering chambers upto the ejection position.
A stop pin protruding from the underside of each pusher strikes a locking bar provided in the path of revolution of each pusher to displace the pusher circumferentially at the ejection position in which the apertures in the pusher coincide with the respective metering chambers in the disc and allow the product in the metering chambers to be discharged. Shunts are fixedly disposed above the metering disc in order strip off the product at the upper ends of the metering chambers so that the product in the metering chambers is flush with the top of the metering disc before entrance into the ejection position. The product in the metering chambers at the ejection position is thrust downward into the bottom parts of hard gelatin capsules positioned below the metering disc by a group of tappets that can be moved up and down and can dip into the metering chambers (US 6286567B1).

In the above apparatus, the pushers are displaceable on the metering disc by sliding the pushers on the metering disc on a circular arc to close the metering chambers in the filling position and to open the metering chambers in the ejection position. In order to ensure smooth rotary motion of the pushers on the metering disc, it is necessary to maintain smooth surfaces between the pushers and the metering disc and also very high dimensional accuracies. As a result, the manufacturing cost and time for the pushers and metering disc are increased. The tension springs will start loosing the tension over a period of time and may even fail thereby requiring periodic replacement of the tension springs. With gradual loss of tension of the tension springs, the pushers may not close the metering chambers effectively causing leakage of the product from the metering chambers. As the pushers are displaceably secured to the metering disc, it becomes necessary to dismantle the metering disc and the pushers in order to clean or change the metering disc. This is cumbersome and inconvenient and time consuming to carry out and also requires labour.
In another design, a capsule filling machine for producing hard gelatin capsules containing pharmaceutical material particles, in particular microtablets or pellets, comprises a carousel that rotates about a vertical axis intermittently and that includes a plurality of slide units for holding and handling the capsules. The machine also comprises feed means having at least one hopper containing a mass of these particles and a roller rotatable about a horizontal axis partly immersed in the mass of particles in the hopper. The roller comprises a plurality of suction recesses for accommodating and retaining a predetermined number of the particles drawn from the hopper and then releasing the particles into a series of hollow open ended conduits mounted on the carousel and uniformly distributed on the carousel.

The conduits are provided with reciprocating plates for closing the bottom ends of the conduits in order to collect the particles falling out of the recesses of the roller and for opening the bottom ends of the conduits in order to discharge the particles into capsule bodies positioned below the conduits. The machine also comprises detection means for checking whether the recesses are properly filled with the predetermined number of particles and a rotary scraper coupled with the roller and designed to enable the hollow recesses to be correctly filled and to cause the excess particles to fall back into the mass in the hopper (WO 2007/012966 Al).
In the above machine, both the carousel and roller are rotating about a vertical axis and a horizontal axis intermittently, respectively. Therefore, synchronization of the intermittent rotations of the carousel and roller is difficult and complicated. Since the roller with the suction recesses holding the dosages of the product are rotating about a horizontal axis, dimensional accuracies and vacuum pressure are to be precisely controlled in order to maintain consistency and accuracy of the dosages. This makes manufacture and operation of the machine complex and complicated. The pharmaceutical particles first get transferred into the hollow conduits and from the conduits into the empty capsule bodies. As a result, the cycle time of the machine increases and its productivity reduces.
In another design, a device for filling capsules with pellets, comprises dosing members provided with dosing chambers disposed below a container containing pellets to be formed into dosages. The dosing members with dosing chambers are slidable back and forth against abutting surfaces horizontally. Vertically

reciprocating plungers with actuators are provided to produce a mechanical force acting upon the pellets in order to fill the dosing chambers with the pellets and/or eject the pellets from the dosing chambers. (WO 2007/062980 Al)
In the above device .there are chances for the pellets to get crushed and damaged between the dosing chambers and the abutting surfaces during the sliding movement of the dosing chambers containing dosages against the abutting surfaces. This will cause not only loss of valuable material and dust generation but will also reduce the dissolution properties of coated pellets. It may also cause weight variations and dosage variations of the filled capsules. The particulate material may also clog the clearance between the dosing chambers and abutting surfaces and obstruct the smooth sliding movement of the dosing members against the abutting surfaces. Synchronisation of the up and down movements of the plungers and horizontal sliding movement of the dosing members is also quite difficult and complicated.
In another design, a machine for metering microtablets, comprises a cylindrical base subjected to vibration and rotation about a vertical axis and a circular metering surface mounted at the top of the base. The metering surface comprises a number of sloping surfaces, along which the microtablets travel upwards and a respective number of open ended pockets, each for receiving the microtablets from a respective surface. Each of the pockets comprises a bottom wall movable between a fully closed position and a fully open position. Cam member cooperates with the bottom walls of the pockets to close and open the pockets and to retain the microtablets in the pockets and discharge them from the pockets respectively. Through holes are provided in the metering surface to prevent more than the predetermined number of

microtablets from being deposited in the pockets. A slanting supporting plate is provided below the cam member to slide the microtablets dropping out of the open pockets into capsule bodies positioned below the supporting plate. A catch bin is provided for the microtablets sliding off the supporting plate (US7857014B2).
In the above machine, effective functioning of the metering surface depends on the geometry and dimensional accuracy thereof. Therefore, the metering surface is quite complicated and complex in construction in terms of geometry and dimensional accuracy. Vibratory and rotary motions of the base and metering surface also render the construction of the machine quite complex and complicated. It is quite difficult to synchronise and control the vibratory and rotary movements of the base and metering surface. Because of the vibratory and rotary motions, there are also chances for the microtablets dropping down from the pockets and sliding off the supporting plate to miss the catch bin thereby leading to wastage of valuable of material and losses. The machine comprises a large number of moving components thereby increasing maintenance cost and reducing reliability.
In our Indian patent application No 971/MUM/2008 filed on 6 May 2008, we have described a capsule filling machine comprising a dosing chamber having a dosing disc rotatably held at the underside thereof. The dosing disc is mounted on a vertical shaft adapted to describe an intermittent rotary motion. A plurality of stations are provided angularly equidistantly around the periphery of the dosing disc. Each of the stations comprises a group of through vertical passages provided at the periphery of the dosing disc on a pitch circle to form metering chambers and a plurality of radial slide means each corresponding to each station and disposed underside the dosing disc in

abutment therewith and supported on a support disc mounted on the said vertical shaft.
The radial slide means comprises a radial slide member radially slidably located in a seat in the support disc and formed with a group of through vertical grooves corresponding to the group of metering chambers. The slide member is spring biased radially outwardly such that the groups of vertical grooves are offset with the groups of metering chambers. The radial slide means also comprises displacement means for displacing the slide member radially inwardly to coincide the corresponding vertical grooves with the corresponding group of metering chambers.
The slide member is T-shaped and the vertical grooves are formed in the cross-flange thereof. The displacement means comprises a vertically rotatably held swivel rod, the upper end of which is located in a cross channel formed underneath the perpendicular flange of the slide member and protruding down through a slot in the seat in the support disc. The swivel rod is formed with a lateral extension at the upper end thereof corresponding to the inward radial displacement of the radial slide member. The displacement means also comprises drive means for vertically angularly displacing the swivel rod, the crosschannel underneath the slide member restricting the radial movement of the slide member by abutting against the respective opposite side walls of the slot in the seat of the support disc.
The drive means comprises a pneumatic cylinder connected to the lower end of the swivel rod through a linkage comprising a U-shaped link fitted to the piston rod of the pneumatic cylinder and a tapered link the narrow end of which is disposed in the U-

shaped link and pivoted thereto, the lower end of the swivel rod being fitted to the wide end of the tapered link.
In the above machine, the metering chambers get filled up with material at the respective stations under gravity and tamping. Because of this, the metering chambers may not get filled with the material to the required doses. This may cause weight variations and dosage variations of the filled capsules. This is detrimental, especially in the case of machines used for microdosing. Besides, the radial slide means at all the stations of the machines increases the overall cost of the machine.
A capsule filling machine of our design for micro-dosing dry medicinal powder comprises a dosing chamber disposed for rotation about a vertical axis intermittently. The dosing chamber comprises a circular dosing disc at the bottom thereof and a circular sidewall projecting upwardly from the periphery of the dosing disc defining a space within the sidewall for the powder. Groups of metering chambers are provided in the dosing disc transversely through the periphery thereof in a radially and equidistantly distributed manner. A plurality of bottom plates corresponding to the number of groups of metering chambers are disposed underneath the dosing disc concentric with and radially slidably engaged to the dosing disc. Each of the bottom plates comprises a group of discharge openings transversely therethrough registering with a group of metering chambers in the dosing disc.
In a cycle of operation of the machine, the dosing chamber with the bottom plates describe intermittent rotary motion about a vertical axis around three filling stations, two filling and tamping stations and an ejection station. The discharge openings in

the bottom plates remain misaligned with the metering chambers in the dosing disc while the dosing chamber with the bottom plates describe intermittent rotary motion about the filling stations and filing and tamping stations upto the ejection station.
Dry powder gets filled in the metering chambers at the filling stations under gravity. Dry powder gets further filled in the metering chambers at the filing and tamping stations to the required volume and dosage under gravity and mild compaction with tamping pistons moving up and down at the filling and tamping stations. When the dosing chamber and a bottom plate with fully filled metering chambers reach the ejection station, the discharge openings in the respective bottom plate are radially aligned with the metering chambers in the dosing disc. Usually a pneumatic cylinder is used to displace the respective bottom plate radially and align with the metering chambers in the dosing disc. A group of pushers up and down movably disposed at the ejection station move down and enter the metering chambers and push the doses of powder out into bottom capsule bodies positioned below the metering chambers at the ejection station.
In such a machine there are chances for the powder particles to remain in the metering chambers proceeding to the first filling station from the ejection station in the next cycle of operation of the machine. There are also chances that the metering chambers may not get filled up to the required volume due to gravity filling and due to possibility of micro air pockets formation in the powder doses in the metering chambers during gravity filling. Because of these problems the filled capsules will not get accurately and correctly filled up with powder and weight variations and dosage variations of the filled capsules may occur. There are also chances for the

powder doses to get agglomerated under gravity filling. All of this can be very detrimental and critical, especially in the case of capsules filled with microdoses.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a capsule filling machine for dosing capsules with dry powder, comprising a dosing chamber having a circular dosing disc at the bottom thereof and a circular sidewall projecting upwardly from the periphery of the dosing disc defining a space within the sidewall for the powder, the dosing disc having groups of metering chambers extending transversely through the periphery thereof in a radially and equidistantly distributed manner and a plurality of bottom plates corresponding to the number of groups of metering chambers disposed underneath the dosing disc concentrically with and radially slidably engaged to the dosing disc, each of the bottom plates having a group of discharge openings transversely therethrough matching with a group of metering chambers, wherein the dosing chamber is disposed for rotation about a vertical axis intermittently around an air cleaning station, atleast one suction filling station, a suction filling cum tamping station, a levelling cum suction filling cum tamping station and an ejection station.
BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying schematic drawings:
Fig 1 is a plan view of the capsule filling machine according to an embodiment of the invention without the radial slide mechanism at the ejecfion station thereof;

Fig 2 is a sectional view of the machine of Fig 1 at the ejection station;
Fig 3 is a scrap sectional view of the dosing chamber, a bottom plate and support pad of the machine of Fig 1;
Fig 4 is a plan view of a bottom plate of the machine;
Fig 5 is a plan view of the support pad of the machine of Fig 1 supported on vertically equidistantly disposed pneumatic cylinders and guided on upright guides;
Fig 6 is a view of the air cleaning station of the machine of Fig 1 partly in section;
Fig 7 is a partial sectional view of a suction filling station of the machine of Fig I;
Fig 8 is a partial sectional view of a suction filling cum tamping station of the machine of Fig 1;
Fig 9 is a partial sectional view of a levelling cum suction filling cum tamping station of the machine of Fig 1;
Fig 10 is a partial sectional view of the ejection station of the machine of Fig 1 including the radial slide mechanism;
Fig 11 is a plan view of the machine of Fig 1 including the radial slide mechanism;
and

Fig 12 is a partial sectional view of the dosing chamber, bottom plate and support pad of the machine of Fig 1 guided on an upright guide.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION The capsule filling machine 1 for dosing capsules with dry powder as illustrated in Figs 1 to 12 of the accompanying drawings comprises a dosing chamber 2 having a circular dosing disc 3 at the bottom thereof and a circular sidewall 4 projecting upwardly from the periphery of the dosing disc defining a space 5 within the sidewall for the powder 6. The dosing disc comprises groups of metering chambers 7 extending transversely through the periphery thereof in a radially and equidistantly distributed manner. A plurality of bottom plates 8 corresponding to the number of groups of metering chambers are disposed underneath the dosing disc concentrically with and radially slidably engaged to the dosing disc. Each of the bottom plates comprises a group of discharge openings 9 extending transversely therethrough matching with a group of metering chambers 7.
The dosing chamber is disposed for rotation about a vertical axis comprising vertical shaft 10 intermittently around an air cleaning station A, two suction filling stations B and C, a suction filling cum tamping station D, a levelling cum suction filling cum tamping station E and an ejection station F. Each of the bottom plates 8 further comprises a group of air inlet cum suction holes 11 extending transversely therethrough radially spaced apart from the respective group of discharge openings 9 and matching with a group of metering chambers 7 in the dosing disc 3. Each of the air inlet cum suction holes in the bottom plate is provided with a mesh 12 at the top

thereof having interstices (open spaces in the mesh) slightly smaller than the sizes of the powder particles.
The bottom plates are associated with a support pad 13 disposed underneath the bottom plates 8 for guided up and down movement. The support pad is supported on vertically equidistantly disposed pneumatic cylinders 14 for up and down movement thereof. The support pad comprises a depression 15 at the bottom surface thereof and is guided on upright guides 16 during the up and down movement thereof by engaging the top ends of the upright guides in the depression (Fig 12). The support pad rests against rester nuts 17 on the upright guides and the rester nuts are locked in position on the upright guides with lock nuts 18. The height of the support pad and hence the travel of the support pad can be adjusted by adjusting the position of the rester nuts on the upright guides and locking the rester nuts in position on the upright guides with the lock nuts. The support pad is spring biased towards the upright guides with tension springs 19.
The support pad comprises a plurality of air cum suction effect distributors 20 at the bottom thereof corresponding to the number of stations. The support pad further comprises a group of air inlet holes 21 extending transversely therethrough matching with a group of air inlet cum suction holes 11 with meshes 12 in a bottom plate 8 and a group of metering chambers in the dosing disc at the cleaning station A and connected to an air source (not shown) at the air cleaning station A through the respective air cum suction effect distributor 20 at the station A and air inlet opening 22 in the distributor 20 (Fig 5). A group of metering chambers in the dosing disc corresponding to a group of air inlet cum suction holes 11 with meshes 12 in a bottom

plate at the air cleaning station A are also connected to a blower 23 via a powder isolator block 24 disposed above the group of metering chambers in the dosing disc 3 and a dust collector 25 and a filter cartridge 26 disposed in the dust collector (Fig 6).
The isolator block 24 describes a clearance (not shown) with the dosing disc. The clearance between the dosing disc and the isolator block is marginally smaller than the particle size of the powder. The support pad also comprises groups of air inlet cum suction ports 27 extending transversely therethrough matching with the groups of air inlet cum suction holes 11 with mesh 12 in the bottom plates 8 and corresponding groups of metering chambers in the dosing disc and connected to a vacuum source (not shown) via the respective air cum suction effect distributors 20 at the bottom of the support pad and a vacuum opening 28 in the distributors 20 at the suction filling stations B and C, suction filling cum tamping station D and levelling cum suction filling cum tamping station E, respectively (Fig 5). The support pad also comprises a relief 29 at the ejection station F (Fig 5).
The suction filling cum tamping station D comprises a group of tamping pistons 30 corresponding to a group of metering chambers 7 up and down movably disposed above a group of metering chambers at the respective station (Fig 7). The outer periphery of the tamping pistons 30 is slightly larger than the inner periphery of the metering chambers and the stroke of the pistons is limited up to the mouth of the metering chambers. The levelling cum suction filling cum tamping station E also comprises a group of tamping pistons 31 corresponding to a group of metering chambers up and down movably disposed above a group of metering chambers at the

respective station through a powder levelling block 32 located at the levelling cum suction filling cum tamping station E at a level above the dosing disc 3 (Fig 9). The outer periphery of the tamping pistons 31 is slightly larger than the inner periphery of the metering chambers and the stroke of the pistons is limited upto the mouth of the metering chambers.
The ejection station comprises a group of pushers 33 corresponding to a group of metering chambers up and down movably disposed above the metering chambers through the powder isolator block 24 (Fig 2). The outer periphery of the pushers is slightly smaller than the inner periphery of the metering chambers and the lower end of the pushers is tapered marked 33a.
The bottom plates each is mounted on a slider 34 slidabiy engaged over a guide rod 35 laterally extending from the vertical axis 10 radially with respect to the dosing disc 3 and having an arcuate channel 36 across the bottom surface thereof (Figs 10 and 11). 37 is a vertically disposed motor having a flange 38 mounted to the motor shaft 39. A cam follower 40 is disposed in a cam groove 41 formed in the flange and mounted to one end of a horizontally disposed driven arm 42. The other end of the driven arm is mounted to the lower end of a vertically rotatably disposed spindle 43. 43a is a sleeve in which the spindle is rotatably supported and sleeve 43a is mounted to the machine frame 43b (Fig 10). 44 is a horizontally disposed driver arm one end of which is fixed to the upper end of the spindle. 45 is a vertically disposed finger one end of which is fitted to the other end of the driver arm. The other end of the finger is aligned with the arcuate channel 36 across the bottom surface of the slider 34 and so positioned and dimensioned as to engage in and disengage from the channel.

At the beginning of a cycle of operation of the machine, the various groups of air inlet cum suction holes 11 with meshes 12 in the bottom plates 8 are aligned with the respective groups of metering chambers 7 in the dosing disc 3. A group of empty metering chambers 7 arrived from ejection station F in the previous cycle dowel 1 at the air cleaning station A, a group of air cleaned metering chambers arrived from air cleaning station A in the previous cycle dowell at the suction filling station B, a group of metering chambers filled with powder arrived from suction filling station B in the previous cycle dowell at the suction filling station C. a group of metering chambers filled with powder arrived from suction filling station C in the previous cycle dowell at suction filling cum tamping station D, a group of metering chambers filled with powder arrived from suction filling cum tamping station D in the previous cycle dowell at levelling cum suction filling cum tamping station E and a group of metering chambers filled with powder arrived from levelling cum suction filling cum tamping station E in the previous cycle dowell at ejection station F ready for ejection.
The pneumatic cylinders 14 are operated to move up the support pad 13 and abut against the bottom plates 8 with the group of air inlet holes 21 in the support pad aligned with the group of air inlet cum suction holes 11 with meshes 12 in the respective bottom plate 8 at the air cleaning station A and with the groups of air inlet cum suction ports 27 in the support pad aligned with the groups of air inlet cum suction holes 11 with meshes 12 in the respective bottom plates at stations B, C, D and E. Air is injected through the holes 11 and meshes 12 in the bottom plate and respective metering chambers at station A via respective air cum vacuum effect distributor 20 at the bottom of the support pad and air inlet opening 22 in the

distributor 20 and air inlet holes 21 in the support pad. The blower 23 sucks in the air from the metering chambers at station A via the powder isolator block 24 and dust collector 25 and filter cartridge 26 and throws out the air. While the air flows through the holes 11 and meshes 12 and metering chambers at station A, dust particles, if any, remaining in the holes 11 and meshes 12 and metering chambers at station A are carried by the air and are trapped by the filter cartridge. The dust particles get collected in the dust collector and are removed from the dust collector periodically. The holes 11 and meshes 12 and the metering chambers at station A are thus air cleaned free of dust particles.
Simultaneously, powder is sucked into the metering chambers at stations B, C, D and E by applying a vacuum in the metering chambers through the respective air cum vacuum effect distributors 20 at the bottom of the support pad and vacuum openings 28 in the distributors 20 and air inlet cum suction ports 27 in the support pad and air inlet cum suction holes 11 with meshes 12 in the bottom plates 8 (Figs 7. 8 and 9). The powder gets filled up incrementally at stations C, D and E and mild compaction of the powder also takes place at stations D and E with the respective pistons 30 and 31 moving up and down to ensure that the metering chambers are filled upto the required dosages.
The outer periphery of the pistons 30 and 31 being slightly larger than the inner periphery of the metering chambers and the travel of the pistons being limited upto the mouth of the metering chambers at stations D and E, the pistons do not enter the metering chambers. Instead the powder in the metering chambers at stations D and E is mildly compacted by the tamping pistons moving up and down at the respective

stations. The levelling block 32 at the station E ensures a constant depth and level of the powder at station E. Because of this, a uniform depth of the powder to be compacted in the metering chambers at station E and uniformity and consistency of the dosages in the metering chambers is ensured. As the interstices of the meshes 12 in the air inlet cum suction holes 11 in the bottom plates are marginally smaller than the powder particles, the powder particles do not leak out through the meshes while suction is applied through the metering chambers at stations B. C, D and E and at the same time the powder is retained in the metering chambers at stations B, C. D and E. Because of the air cleaning at station A, powder particles if any trapped in the interstices of the meshes are also effectively removed. As the clearance between the isolator block 24 and the dosing disc 3 is marginally smaller than the size of the powder particles, the powder particles in the dosing chamber outside the isolator block do not get into the isolator block at station E so as to maintain consistency of the dosages.
The dosages in the metering chambers at the ejection station F are retained in the metering chambers because of the meshes 12 in the holes 11 in the respective bottom plate 8. Simultaneously, the motor 37 rotates in the vertical plane and the cam follower 40 describes a rotary motion in the vertical plane in the cam groove 41 in the flange 38 on the motor shaft 39. The rotary motion of the cam follower is transmitted to the finger 45 via the driven arm 42, spindle 43 and driver arm 44. The finger engages in the arcuate channel 36 across the bottom surface of the slider 34 and slides the slider radially inwardly on the guide rod 35. As a result, the respective bottom plate slides radially inwardly with the slider and aligns the discharge openings 9 in the bottom plate with the metering chambers containing the dosages in the dosing disc.

The pushers 33 up and down movably positioned at the ejection station F move down and dip into the metering chambers at station F to push down the doses in the metering chambers into the capsule bodies 46 positioned below the bottom plate.
As the outer periphery of the pushers is slightly smaller than the inner periphery of the metering chambers and the lower ends of the pushers are tapered, the pushers enter the metering chambers and push out the doses from the metering chambers effectively. Because of the relief 29 in the support pad 13, the capsule bodies can be conveniently positioned below the bottom plate to receive the powder doses. On receiving the doses in the capsule bodies, the capsule bodies are moved away from the ejection station. Mechanisms for handling the capsule bodies are known and have not been illustrated and described as such is not necessary for understanding the invention.
During continued rotation of the motor, the cam follower describes a rotary motion in the cam groove in the vertical plane in the opposite direction and the finger describes a corresponding rotary motion in the opposite direction in the vertical plane and retracts the slider and the bottom plate to the original position. The air inlet cum suction holes 11 and meshes 12 in the bottom plate align with the empty metering chambers 7 in the dosing disc 3 at station F. The pneumatic cylinders 14 are operated to lower the support pad 13 and allow the dosing disc with bottom plates to index or rotate to the successive stations and start the next cycle of operation of the machine. The tension springs 19 help to move up and move down the support pad.

According to the invention the empty metering chambers returning to the air cleaning station A after each cycle of operation of the machine are air cleaned to free the empty metering chambers from dust particles. The cleaned metering chambers are filled up with the powder increment!}' at the following stations under suction and mild compaction to ensure that the metering chambers are positively filled upto the required doses. Because of the levelling block, a constant depth and level of the powder is available at the levelling cum suction filling cum tamping station to further ensure that the metering chambers are positively filled to the required doses. Because of the vacuum filling possibility of micro air pockets formation in the powder doses in the dosing chambers is eliminated. All this ensures that weight variations and dosage variations of the filled capsules are eliminated and that the capsules are correctly and accurately with the required dosages.
Furthermore, according to the invention the dosing chamber with the bottom plates rotates about a vertical axis. Only the rotary motion of the dosing chamber is required to be synchronised. The metering chambers filled with powder do not slide against the bottom plates or any other surface. Therefore, the powder does not get damaged and does not obstruct rotation of the dosing disc with metering chambers as in the conventional art. The machine comprises few moving parts and is simple in construction and cost effective and requires low maintenance. Cycle time of the machine is reduced thereby increasing productivity. As the filling is done under suction and mild compaction the powder is loosely held well dispersed without agglomeration and micro air pockets. Therefore, the capsule filling machine of the invention is suitable, especially for micro-dosing.

It is understood that several variations of the above embodiment of the invention are possible without deviating from the scope of the invention. The configurations of the air cleaning station, suction filling stations, suction filling cum tamping station, levelling cum suction filing cum tamping station and ejection station can be different. The number of suction filling stations, suction filling cum tamping station and levelling cum suction filling cum tamping station can be different. There can be also a single suction filling station. The number of metering chambers in each group of metering chambers in the dosing disc and corresponding number of air inlet cum suction holes in the bottom plates can vary.
The number of pneumatic cylinders for moving the support pad up and down can be different. The number of upright guides for the support pad can be different. The support pad can be height adjustably supported in a different manner. The radial slide mechanism for displacing the bottom plate at the ejection station can be different. Capsule filling machines are generally used for filling medicinal or neutraceutical powder. However, the powder used for filling can be any other powder also. Such variations of the invention are obvious to a person skilled in the art and are to be construed and understood to be within the scope of the invention.

We claim :
1. A capsule filling machine for dosing capsules with dry powder, comprising a dosing chamber having a circular dosing disc at the bottom thereof and a circular sidewall projecting upwardly from the periphery of the dosing disc defining a space within the sidewall for the powder, the dosing disc having groups of metering chambers extending transversely through the periphery thereof in a radially and equidistantly distributed manner and a plurality of bottom plates corresponding to the number of groups of metering chambers disposed underneath the dosing disc concentrically with and radially slidably engaged to the dosing disc, each of the bottom plates having a group of discharge openings transversely therethrough matching with a group of metering chambers, wherein the dosing chamber is disposed for rotation about a vertical axis intermittently around an air cleaning station, atleast one suction filling station, a suction filling cum tamping station, a levelling cum suction filling cum tamping station and an ejection station.
2. The capsule filling machine as claimed in claim 1, wherein each of the bottom plates further comprises a group of air inlet cum suction holes transversely therethrough radially spaced apart from the respective group of discharge openings and matching with a group of metering chambers in the dosing disc, each of the air inlet cum suction holes being provided with a mesh at the top thereof having interstices slightly smaller than the powder particles, and wherein the bottom plates are associated with a support pad disposed underneath the bottom plates for guided up and down movement, the support

pad having a group of air inlet holes transversely therethrough matching with a group of air inlet cum suction holes in a bottom plate and connected to an air source at the air cleaning station and farther having groups of air inlet cum suction ports transversely therethrough matching with a group of air inlet cum suction holes in a bottom plate and connected to a vacuum source at the suction filling station, suction filling cum tamping station and levelling cum suction filling cum tamping station and the support pad farther having a relief at the ejection station.
3. The capsule filling machine as claimed in claim 2, wherein the air cleaning station further comprises an filter unit communicating with a group of metering chambers at the air cleaning station.
4. The capsule filling machine as claimed in claim 3, wherein the air filter unit comprises dust collector communicating with the group of metering chambers at the air cleaning station and a filter cartridge disposed in the dust collector and connected to a blower.
5. The capsule filling machine as claimed in claim 1, wherein the suction filling cum tamping station comprises a group of tamping pistons corresponding to a group of metering chambers up and down movably disposed above the group of metering chambers at the respective station, the outer periphery of the tamping pistons being slightly larger than the inner periphery of the metering chambers and the stroke of the pistons being limited upto the mouth of the metering chambers.

6. The capsule filling machine as claimed in claim 1. wherein the levelling cum suction filling cum tamping station comprises a group of tamping pistons corresponding to a group of metering chambers up and down movably disposed above the group of metering chambers at the respective station through a powder levelling block located at the respective station at a level above the dosing disc, the outer periphery of the tamping pistons being slightly larger than the inner periphery of the metering chambers and the stroke of the pistons being limited upto the mouth of the metering chambers.
7. The capsule filling machine as claimed in claim 1, wherein the ejection station comprises a group of pushers corresponding to a group of metering chambers up and down movably disposed above the metering chambers in a powder isolator block located above the dosing disc describing a close clearance with the dosing disc at the respective station, the clearance between the dosing disc and the isolator block being slightly smaller than the size of the powder particles and the outer periphery of the pushers being slightly smaller than the inner periphery of the metering chambers and the lower end of the pushers being tapered.
8. The capsule filling machine as claimed in claim 1, wherein the ejection station comprises a radial slide mechanism for sliding a bottom plate radially at the ejection station.

9. The capsule filling machine as claimed in claim 8, wherein the bottom plates each is mounted on a slider radially slidably engaged over a guide rod extending radially with respect to the dosing disc and having an arcuate channel across the bottom surface thereof and wherein the radial slide mechanism comprises a vertically disposed motor having a flange mounted to the motor shaft, a cam follower disposed in a cam groove formed in the flange and mounted to one end of a horizontally disposed driven arm with the other end of the driven arm being mounted to the lower end of a vertically rotatably positioned spindle, a horizontally disposed driver arm one end of which is fixed to the upper end of the spindle and a vertically disposed finger one end of which is fitted to the other end of the driver arm and the other end of which is aligned with the arcuate channel across the bottom surface of the slider and is so positioned and dimensioned as to engage in and disengage from the arcuate channel.
10. The capsule filling machine as claimed in claim 2, wherein the support pad is supported on vertically equidistantly disposed pneumatic cylinders for up and down movement thereof and comprises a depression at the bottom surface thereof, whereby the support pad is engaged over the top ends of the upright guides for guided up and down movement thereof.
11. The capsule filling machine as claimed in claim 10, wherein the support pad is tension spring biased towards the upright guides.

12. The capsule filling machine as claimed in claim 11, wherein the support pad is height adjustably mounted on the upright guides.