The instant application should be granted the priority dates of Nov. 4, 2011, the filing date of the corresponding German patent application DE 10 2011 117 628.8 as well as Nov. 3, 2012, the filing date of the International patent application PCT/EP2012/004595.

BACKGROUND OF THE INVENTION

The invention relates to a freeze-drying apparatus.

In many cases, freeze-drying plants are designed for discontinuous operation, and consist primarily of a drying chamber and a condenser chamber that communicates with the drying chamber via a closable opening, wherein the product to be dried is contained in a wide range of drying receptacles, vials, ampoules or even dishes, which are placed on a support surface inside the drying chamber for the drying process to be carried out. Inside the drying chamber, a plurality of such support surfaces are arranged one above the other at a distance from each other in a rack arrangement so as to be vertically displaceable. Depending on the size of the freeze-drying apparatus, it is possible that a large number of drying receptacles—each containing a defined quantity of goods for drying—may have to be placed inside the drying chamber for a drying process and taken out again when the process is complete, so the use of automated apparatuses both for loading and unloading the drying receptacles is commonplace, although nowadays it must be specified when drying units are ordered whether loading and/or unloading is to be carried out by hand or with the aid of suitable, automated equipment. At the moment, converting a freeze drying unit that is loaded and/or unloaded manually to an integrated, automated process is not possible, or only possible at great expense.

In view of the sensitivity to temperature of the goods to be dried, and especially because of the need to ensure absolutely aseptic conditions for all components of the unit that come into contact with the goods to be dried, the initial design of a loading and unloading device must include extremely careful consideration of the way in which the construction and mode of operation of such a device respond to the imperatives of aseptic manufacturing.

SUMMARY OF THE INVENTION

A freeze-drying system is known from WO 2005/121671 A1, in which the receptacles are transported upright on a conveyor belt to a position in front of the input opening of the system housing, and are then moved into the housing one row at a time in a direction perpendicular to the direction of advance of the conveyor belt so that drying can take place. The drying receptacles are moved using a device consisting of two carriages supported on guides extending on either side of a product platform located in a loading position, which two carriages are connected to one another by a pusher bar, wherein the pusher bar serves both to push the drying receptacles in and to push the drying receptacles out after drying is complete. For this purpose, the pusher bar may be swiveled about an axis extending parallel to the product platform between a lowered, active position, that is to say in a position for resting flush against the drying receptacles, and a raised, inactive position, that is to say in a position for passing above the drying receptacles standing on the product platform. Accordingly, in order to eject the drying receptacles, the pusher bar is first swiveled into the inactive position, advanced into the housing above the drying receptacles, and finally swiveled back into the active position thereof when it has reached the rear of the group of drying receptacles on the far side with respect to the input opening, where it is ready to push the receptacles out. This process presents difficulties because it involves travelling over the drying receptacles, particularly in terms of preserving aseptic conditions because abrasion is unavoidable.

The freeze-drying system known from DE 103 07 571 A1 is characterized in that a pusher is provided in a direction perpendicular to the direction of advance of the conveyor belt in order to push the drying receptacles initially standing upright on a conveyor belt one row at a time into the housing thereof, and a pusher bar is also provided, and is aligned parallel to the pusher and can be advanced into the housing and withdrawn therefrom by means of two chain hoists running along the sides of the product platform in the loading and unloading position. In this case too, the ends of the pusher bar can be swiveled about a horizontal axis, between a lowered, active position, that is to say in which it is designed to lie flat against the group of upright drying receptacles and a raised, inactive position, in which it is designed to travel over the group. In the same way as in the system according to WO 2005/121671 A1, the process of travelling over the drying receptacles must be considered critical. Furthermore, two separate mechanical systems and associated drive systems are required to push the drying receptacles into and out of the drying unit. This represents a not inconsiderable design engineering challenge.

Finally, a further freeze-drying system is known from DE 60 2004 003 692 T2, in which a pusher is provided that can be advanced into the housing through the input opening therein in order to push drying receptacles into the unit one row at a time, wherein the group of drying receptacles that is pushed into the housing is positioned flat against a bar that can also be advanced into the housing during the pushing process, which bar serves to stabilize the drying receptacles in the upright position. Each end of the bar is supported by a carriage and can be swiveled thereon between a lower, active position flush with the drying receptacles and an upper, inactive position designed to enable it to travel over the group of drying receptacles.

The pusher and the bar can be withdrawn completely from the housing. When the drying receptacles are pushed out, the bar functions as an ejector, whereas the pusher performs a stabilizing function. Apart from the need to travel over the drying receptacles, a disadvantage of this embodiment is the fact that two pushing mechanisms that are independent of one another, and the associated drive systems are provided, one of which can be switched between two positions, that is to say an active and inactive position.

The drawback associated with the use of a pusher bar that can be swiveled between an active and an inactive position, and which is operatively connected for example to laterally attached chain hoists or other tractive and pressing means to enable it to travel over the drying receptacles, is that additional space is required to accommodate the necessary guides therefor, which inevitably increases the dimensions of the drying chamber.

In view of the situation described in the preceding, the object of the invention is to design a freeze-drying apparatus of the type described in the introduction to such effect that aseptic conditions may be assured with a simple construction and also in simple manner when the apparatus is in operation. This object is solved with such a freeze-drying system by the features listed in the characterizing part of claim1.

It is essential for the purposes of the invention that only one carriage is needed, the front and rear sides of which each form a movable leading edge for the drying receptacles, to assure the operation of pushing into the drying chamber and the operation of pushing out of the drying chamber. It is also essential for the purposes of the invention that the operation of advancing the carriage into the drying chamber for the purpose of bringing the front side thereof facing toward a door in the housing into the starting position for pushing the drying receptacles out, which corresponds to the extreme rear position, is always performed in conjunction with travelling below loaded product platforms. Since travelling above loaded product platforms is entirely avoided in this way, problems created by the abrasion that is inevitably associated with the movement of the carriage are prevented entirely, and aseptic conditions are thus preserved.

The advance of the carriage into the drying chamber at the start of and during the subsequent unloading of the product platforms takes place on a shift level that may be an empty product platform, the pressure plate for aligning product platforms or even the space below the pressure plate. The system movement always takes place below the product platform that is initially to be unloaded, the surface is only lowered afterwards, and this is followed by the unloading operation.

The guides designed to serve as bearings for the carriage are disposed at a fixed height and define the position of the shift level.

A conveyor belt with a direction of advance that is transverse to the input and ejection direction forms a part of the loading and unloading device.

A transport trolley, the size of which is determined by the product platform and which also has a parking position for the carriage as well as the guides described may also be used instead of a conveyor belt. Such a transport trolley does not comprise a conveyor belt.

The loading and unloading device comprises a loading stage, the guides of which cooperate with the guides inside the drying chamber to support the carriage.

With regard to the second extreme position of the carriage, located outside the drying chamber, this position may be used as a parking position during the drying operation. It is set up on the opposite side of the conveyor belt from the point of view of the drying chamber, if it is to be used at the same time for loading. In other cases it may also be set up on the loading stage.

Different variants of a drive unit for the carriage. In this context, an electric drive unit that may also be a linear drive is used. A preferably inductive charging point may be located at the second limit position for the case that the drive unit is battery-powered.

Further configurations of the drive unit, including the guides allocated thereto, are contemplated. Accordingly, a frictional connection with the guides is preferably imparted by means of a toothed belt, which passes round a number of running wheels and is thus suitable for bridging gaps in segments of the guides. It is essential for the purposes of the invention that the drive unit comprises a housing that accommodates all of the components, including a controller, yet has a slimline construction, with a height equal to that of the guides.

The carriage housing is preferably in the form of a hermetically sealed, particularly watertight unit that is accessible inside the drying chamber for a clean-in-place (CIP) process.

A second carriage is also provided, which performs a counterbalancing function and is otherwise constructed identically, and which is also accommodated in the guides. Both carriages may have a park position on the loading and unloading device, and in the shift level it is always possible for one of the two carriages to be brought into a pushing position and the other to be brought into a position suitable for providing the counterbalancing function. It may be advantageous to implement the counterbalancing function for drying receptacles that are rather unstable in the upright position.

The guides designed to support the carriage. They are constructed with lengthwise segmentation and are displaceable relative to one another. At the same time, they may also be designed as lateral leading edges for the drying receptacles, so that in conjunction with an additional, displaceable arrangement vertical to the longitudinal extension thereof they can easily be adapted to drying receptacles of different dimensions, thereby also providing such receptacles with secure upright support transversely to an insertion or ejection operation, and at the same time preventing jamming or wedging, and thus ensuring that less waste is created among the drying receptacles.

Depending on the shape of the drying receptacles, e.g., when drying dishes, a gap corresponding to the space requirement for suspending the product platforms may be left between the guides. Consequently, the guides do not necessarily have to be advanced until the frontal faces are flush with each other. As was indicated in the preceding, the carriage is also able to bridge gaps between segments in the guides to some degree.

Gear units enclosed in vacuum-tight capsules that are connected to drive units outside the drying chamber are provided for moving the guide segments. In general, the displacement movement of said segments may also be engineered differently, for example it may be connected to the drive unit of the carriage. A gap between two segments may also be bridged by moving telescopically extensible intermediate elements into these gaps.

As an alternative to enabling transverse displacement of the guides, special lateral guides may also be provided, which are arranged so as to be movable independently of the guides that are designed to accommodate the carriage.

A structural unit designed as a bearing for the loading and unloading device is provided and is arranged so as to be movable toward and away from the drying chamber, that is to say parallel to the direction of insertion and extraction. This variation may be used particularly advantageously for maintenance purposes. Said structural unit may for example be arranged displaceably on rails.

In the preceding, the freeze-drying system has been described in conjunction with a drying chamber that is loaded and unloaded through a single opening. The object of the invention is also usable in a unit that is designed for reach-through operation and is accordingly provided with two openings positioned opposite one another, with a loading and unloading device allocated to each.

The further refinement of the freeze-drying system applies to the version of a system of supports for the product platform located in the shift level that is known per se. This enables the height of the shift level in the drying chamber to be adjusted independently, and is embodied for example by an arrangement of bolts that are displaceable in the shift level relative to the product platform between an active position, in which a support function is fulfilled, and an inactive position, in which a support function is not fulfilled.

A further object of the invention is to design a method for operating a freeze-drying system according to the invention that enables operation under aseptic conditions by simple means.

