Adiabatic high pressure generation

Abstract

The invention relates to a system for transforming plastics material preforms into plastics material containers having a plurality of blow molding stations which are arranged on a carrier and in each case comprise a blow mold for expanding plastics material preforms into plastics material containers inside this blow mold by means of a pressurized pneumatic medium which is supplied to the respective blow molding station via a pressure supply device and which is at least partially extracted again from the respective blow molding station after the expansion operation via a pressure extraction device. According to the invention it has an energy conversion device, with the aid of which at least part of the potential energy stored in an energy store can be turned into an increase in the potential energy of a pneumatic medium associated with at least one blow mold, wherein the energy conversion device has an intermediate energy storage device, and at least part of the potential energy extracted from the energy store, and the energy transmitted by the energy conversion device, can be stored in the form of kinetic energy in the intermediate energy storage device.

Claims

1. A system for transforming plastics material preforms into plastics material containers, comprising: a plurality of blow moulding stations which are arranged on a carrier, wherein each of the blow moulding stations comprises a blow mould for expanding plastics material preforms into plastics material containers inside the blow mould by a pressurised pneumatic medium which is supplied to the respective blow moulding station via a pressure supply device and which is at least partially extracted again from the respective blow moulding station after the expansion operation via a pressure extraction device; wherein the system further has an energy conversion device; with the aid of which at least part of the potential energy stored in an energy store can be turned into an increase in the potential energy of a pneumatic medium associated with at least one blow mould, wherein the energy conversion device has an intermediate energy storage device, and at least part of the potential energy extracted from the energy store, and the energy transmitted by the energy conversion device; can be stored in the form of kinetic energy in the intermediate energy storage device; wherein the energy conversion device has at least one compression cylinder, wherein a piston of the at least one compression cylinder functions as an energy converter, wherein the at least part of the potential energy extracted from the energy store is used to drive the piston and further used to compress the pneumatic medium in a compression chamber of at least one compression cylinder; wherein the energy store for the potential energy includes at least one of a chamber on at least one of a rear side of the piston or the compression chamber of the at least one compression cylinder.

2. System according to claim 1, wherein the energy conversion device is suitable and intended to extract at least part of the potential energy stored in the energy store, and at least intermittently to store a proportion of this extracted energy in the intermediate energy storage device in the form of kinetic energy, and simultaneously therewith to turn a further proportion of the extracted energy into an increase in the potential energy of the pneumatic medium associated with the at least one blow mould.

3. System according to claim 1, wherein means for pretensioning a piston of a compression cylinder are provided as an energy store for potential energy in the energy conversion device.

4. System according to claim 1, wherein the pneumatic medium which is used in an expansion operation inside a blow moulding station and at least partially delivered to a pressure chamber of a compression cylinder can be used in the energy conversion device as an energy store for potential energy.

5. System according to claim 1, wherein the intermediate energy storage device can have a pivotable or a rotatable mass respectively as kinematic intermediate storage means.

6. System according to claim 5, wherein the kinematic intermediate storage means is an oscillating weight.

7. System according to claim 1, wherein at least an amount of energy of 1 kJ of the energy extracted from the energy store and transmitted by the energy conversion device can be stored intermediately in the intermediate energy storage device.

8. System according to claim 1, wherein a reduction of the pressure of the pneumatic medium within a first blow mould can be coupled to the increase in the pressure of the pneumatic medium in a further blow mould by the energy conversion device.

9. System according to claim 1, wherein the energy conversion device is arranged on the stationary part of the system.

10. System according to claim 1, wherein the system has a driving device for driving the energy conversion device.

11. System according to claim 1, wherein dead space volume of all blow moulding stations is the same.

12. System according to claim 1, wherein on at least one blow moulding station and preferably on all blow moulding stations additional dead space volume can be connected and/or a stroke of at least one compression cylinder can be changed and/or a preliminary blow moulding pressure in at least one blow moulding station can be set independently and/or a pretensioning force in at least one compression cylinder is variable.

13. System according to claim 1, wherein the energy conversion device has at least one compression cylinder and a compression piston surface of the at least one compression cylinder has on at least one side an active surface which is variable in its surface area, wherein preferably the compression piston surface of the compression piston of the at least one compression cylinder has at least one annular surface which can be acted upon and/or at least one circular surface which can be acted upon.

14. System according to claim 1, wherein the energy conversion device has two coupled compression cylinders and is capable of and suitable for supplying several blow moulding stations of the system with pressurised pneumatic medium, wherein the two coupled compression cylinders are preferably coupled without vibration to the system or to the carrier respectively.

15. System according to claim 1, wherein the system has a control device which is suitable for connecting a first blow mould, inside which the pressure of a pneumatic medium is to be reduced, fluidically to an energy conversion device, and wherein moreover the control device is preferably suitable for, simultaneously with or following a fluidic connection of the energy conversion device to the said first blow mould, connecting the energy conversion device fluidically to a further blow mould, inside which the pressure of a pneumatic medium is to be increased or should be increased respectively.

16. Method of expanding plastics material preforms to form plastics material containers inside a blow mould of a blow moulding station by means of a pressurised pneumatic medium; wherein a plastics material preform inside at least one first blow mould of a blow moulding station is acted upon with pressurised pneumatic medium which is provided by means of a pressure supply device and is expanded to form a plastics material container, and after the expansion operation the pneumatic medium is at least partially extracted from the blow mould by means of a pressure extraction device; wherein at least part of the potential energy stored in an energy store is extracted therefrom and converted by an energy conversion device into an increase in the potential energy of a pneumatic medium associated with at least one further blow moulding station; wherein at least a part of the energy transferred from the energy conversion device is stored intermediately in the form of kinetic energy in an intermediate energy storage device, and wherein with the resulting pneumatic medium with increased potential energy at least one plastics material preform is expanded in a blow mould of the at least one further blow moulding station in order to form a plastics material container, the method further comprising: constructing and arranging the energy conversion device to have at least one compression cylinder; wherein a piston of the at least one compression cylinder functions as an energy converter; wherein the at least part of the potential energy extracted from the energy store is used to drive the piston and further used to compress the pneumatic medium in a compression chamber of at least one compression cylinder; wherein the energy store for the potential energy includes at least one of a chamber on at least one of a rear side of the piston or the compression chamber of the at least one compression cylinder.

Description

(1) Further advantages and embodiments are disclosed by the appended drawings. In the drawings:

(2) FIG. 1 shows a schematically illustrated preferred embodiment of a system according to the invention for transforming plastics material preforms into plastic containers in plain view as well as two blow moulding stations in cross-section;

(3) FIG. 2 a force/piston position diagram for a compression and decompression taking place in a compression cylinder;

(4) FIGS. 3a-d four schematic cross-sectional representations of an energy conversion device of further preferred embodiments of a system according to the invention;

(5) FIG. 4 shows a schematic representation of a further preferred embodiment of a system according to the invention in a plan view and in a cross-sectional representation;

(6) FIG. 5 shows a comparison of the process angle of the processing operations of two bottles in the shaping process;

(7) FIG. 6 shows a schematic representation of the embodiment illustrated in FIG. 1 of a system according to the invention, identifying the individual phases in which the plastics material containers are undergoing their transforming operation;

(8) FIG. 7 shows a schematic cross-sectional representation of a compression cylinder of a further preferred embodiment of a system according to the invention;

(9) FIG. 8 shows a schematic cross-sectional representation of a compression cylinder coupled to a crank mechanism;

(10) FIG. 9 shows a qualitative diagram to illustrate the piston force depending from the piston positions in the event of a mechanically coupling of a compression cylinder with a crank mechanism;

(11) FIG. 10 shows a schematic cross-sectional representation of a compression cylinder of a further preferred embodiment of a system according to the invention;

(12) FIGS. 11-14 show illustrations of preferred embodiments of a method for recycling a pneumatic medium used for reshaping.

(13) FIG. 1 shows a schematic representation of a preferred embodiment of a system according to the invention for transforming plastics material preforms into plastics material containers in plain view as well as two blow moulding stations in cross-section. In this case a plurality of blow moulding stations 4 is arranged on a carrier 2. Each blow moulding station 4 has a blow mould 42, inside which a plastics material preform 10 can be expanded into a plastics material container 20 by acting upon a pneumatic medium under pressure. The carrier 2 may preferably be a carrier which is rotatable (preferably about a vertical axis). Furthermore the system has at least one pressure supply device 6 or at least one pressure extraction device 8 respectively, by means of which the pneumatic medium can be supplied to the individual blow moulding stations 4 or extracted from the individual blow moulding stations 4 respectively. In this case the pressure extraction device 8 and the pressure supply device 6 are preferably not in fluid communication with one another. The pressure supply device and the pressure extraction device are preferably conduits.

(14) Likewise two blow moulding stations 4 are illustrated schematically in cross-section In FIG. 1. This indicates the progress of a transforming operation. Thus a plastics material preform 10 is still located inside the blow mould 42 in the blow moulding station 4 illustrated on the right side if FIG. 1. By the introduction of pneumatic high-pressure medium this plastics material preform 10 is inflated to a finished moulded plastics material container 20. The pneumatic high-pressure medium which is necessary for this is supplied to the blow moulding station 4 by means of the pressure supply device 6. In the course of the expansion operation of the plastics material preform 10 to form a finished moulded plastics material container 20, in the illustrated embodiment the carrier turns further anticlockwise, so that after the end of the expansion operation the blow moulding station 4 can now be located at the point on the blow moulding station 4 adjacent to which the second cross-sectional representation of a blow moulding station 4 is shown (in the left side of the drawings). Then there is no longer any plastics material preform 10 in the associated blow mould 42, but instead the finished inflated plastics material container 20 is already located there.

(15) The pneumatic medium which is located in the finished inflated plastics material container 20, and which even after the expansion operation still has a high pressure, can now be at least partially extracted by means of the pressure extraction device and can be used as an energy store for potential energy. For this purpose the blow moulding station 4 can be connected by means of the pressure extraction device 8 to the energy conversion device 86. The energy conversion device 86 is provided and is suitable respectively for turning the energy extracted from the potential energy store into an increase in the pressure of a pneumatic medium, by which either simultaneously or subsequently thereto a plastics material preform 10 is expanded into a plastics material container 20 in a further blow moulding station 4. In this case a temporary excess of extracted energy can be stored intermediately in the form of kinetic energy in an intermediate energy storage device 66 and at a later time this energy can be likewise supplied to the compression operation.

(16) In FIG. 2, with reference to a qualitative diagram, the force F occurring on or to be applied respectively to a piston of a compression cylinder is shown depending from the piston position s in the event of an expansion, characterised by the reference G1, and in the event of a compression of a pneumatic medium, characterised by the reference G2. During an expansion operation the released force decreases as the volume increases. The behaviour is reversed in a compression operation, wherein the force to be applied increases with the compression path. Therefore in the event of a coupling of a pressurising operation and a compression operation initially an excess force is obtained from the force released in the compression. The system 1 according to the invention is suitable for intermediate storage of is the unused energy associated with this excess force and produced in the event of a simple coupling, which is marked in FIG. 2 as a cross-hatched area, in the intermediate energy storage device 66 and to reuse it at the end of the compression operation and to deliver it from the intermediate energy storage device 66 to the compression piston.

(17) FIGS. 3a-d show four schematic cross-sectional representations of an energy conversion device 86 of further preferred embodiments of a system 1 according to the invention. In the embodiment shown in FIG. 3a the energy conversion device 86 has two compression cylinders 7 which are each coupled mechanically by means of their cylinders to a crank mechanism. An oscillating weight 12, in which energy can be stored intermediately in the form of kinetic energy, is provided here as intermediate energy storage device 66. The oscillating weight 12 can be driven by means of a driving device 122. The reference S1 in each case indicates in the compression cylinders 7 the compression side, that is to say the chamber of the compression cylinder 7 in which in this embodiment of the present invention pneumatic medium is introduced and compressed. In this case compression does not take place simultaneously on both compression sides of the two compression cylinders, but pneumatic medium is introduced at high pressure into one compression cylinder, for example by producing a fluid communication with a blow moulding station, in which the transformation operation from a plastics material preform 10 to a plastics material container 20 has been ended. This compression chamber or this pneumatic medium respectively serves as an energy store of potential energy, from which energy can be extracted by the energy conversion device 86 by a reduction of the pressure. The chamber on the compression side S1 of the other compression cylinder is likewise filled with pneumatic medium which is, however, at a lower pressure. Part of the extracted energy is stored intermediately in kinetic energy of the oscillating weight 12 and the other part is converted directly into an increase in the pressure of the pneumatic medium in the other compression cylinder 7. In this case, already during the increase of the pressure or also immediately thereafter, the chamber in which the pressure of the pneumatic medium located therein is increased can be connected fluidically to a further blow moulding station or to the blow mould thereof respectively in which a plastics material preform 10 to be expanded is preferably located.

(18) FIG. 3b shows an energy conversion device 86 in which, by comparison with FIG. 3a, the coupling of the two compression cylinders 7 does not take place by means of an oscillating weight 12, but by means of a hydraulic cylinder 9. An intermediate energy storage of kinetic energy can likewise take place, as illustrated here, by means of the storage of kinetic energy in a hydraulic medium. At the same time a hydraulic drive 94 of the energy conversion device 86 can likewise be implemented by means of the hydraulic cylinder 9.

(19) In the embodiment of an energy conversion device 86 illustrated in FIG. 3c only one compression cylinder is provided. This has two compression sides S1, wherein these two chambers can be spaced apart from one another by an adjustable distance (indicated by arrow P2). More precisely, the compression cylinder 7 has two pistons which are connected to one another (by means of a piston rod). The piston surfaces of these two pistons can be spaced apart from one another, as illustrated by the arrow P2. A stroke adjustment can be implemented by this adjustable spacing. When the spacing between the two piston surfaces is increased, the total volume of the two chambers (the compression sides S1) becomes correspondingly smaller. The intermediate energy storage device 86 can be implemented here over both hydraulic cylinders 9.

(20) The compression cylinder illustrated in FIG. 3c can be driven in each case by the pistons of both compression sides by means of mechanical coupling to a respective hydraulic drive 9. However, it would also be conceivable for the compression cylinder to be driven by only one hydraulic drive 9.

(21) Also in the embodiment of an energy conversion device 86 illustrated in FIG. 3b a stroke adjustment can be implemented in a similar manner to that shown in FIG. 3c. For this purpose a fillable chamber 92 is provided in the hydraulic cylinder 9 for stroke adjustment. In this case the two compression cylinders are no longer connected mechanically by means of one single piston rod, but each compression cylinder 7 is connected by a separate piston rod to the hydraulic cylinder 9. In the hydraulic cylinder 9 the piston surfaces thereof form two walls of the fillable chamber 92 for stroke adjustment.

(22) FIG. 4 shows a schematic representation of a further preferred embodiment of a system 1 according to the invention in a plan view and in a cross-sectional representation; In this case in the right part of the drawing the mode of functioning of the system 1 according to the invention or an embodiment thereof respectively is illustrated using the example of four blow moulding stations 4. It is shown that, by means of the pressure supply device 6 via a distribution device 70, the two outer blow moulding stations 4 can be brought into fluid communication both with one another and also individually or with both blow moulding stations 4 together with the compression chamber of the left compression cylinder 7 of the energy conversion device 86. Analogously, by means of the pressure extraction device 8 via a further distribution device 70, the two inner blow moulding stations 4 can be brought into fluid communication both with one another and also individually or both together with the compression chamber of the right compression cylinder 7 of the energy conversion device 86.

(23) If now in one of the inner blow moulds 42 just one transformation process of a plastics material preform 10 into a plastics material container by means of a pressurised pneumatic medium is concluded, then the greatest possible part of the potential energy located in this pneumatic medium should be used. In this respect it is provided that this energy is used directly for production of a volume of pneumatic medium (from a suitable volume of pneumatic medium at a lower pressure such as for example the so-called preliminary blow moulding pressure) at such a pressure that it is suitable in turn for transforming a plastics material preform 10 into a plastics material container 20. This is carried out by the energy conversion device 86. For this purpose the blow mould 42 is for example brought into fluid communication with a compression chamber (compression side S1) of a compression cylinder. With the assistance of an initial tension or another driving device the pneumatic medium in this compression chamber relaxes as the pressure thereof is reduced. Simultaneously the pressure of the pneumatic medium in the compression chamber of the second compression cylinder 7 is increased. In this case an initial excess force is first of all stored intermediately in the form of kinetic energy and is then returned to the compression operation.

(24) FIG. 4 likewise shows that also in each case two blow moulding stations 4 or blow moulds 42 respectively can be fluidically coupled to one another. Thus in these two blow moulds 42 the pressure is simultaneously reduced and in two further blow moulds 42 the pressure of the pneumatic medium is simultaneously increased.

(25) FIG. 5 shows a comparison of the process angles of the processing operations of two bottles in the shaping process starting from a preform. In this case the circles each represent a cycle of the system 1 for transforming plastics material preforms 10 into plastics material containers 20 (cf. FIG. 1). A typical cycle begins in each case in the white circle segment for example with the introduction of a plastics material preform 10 into a blow mould 42 of a blow moulding station 4. The actual transformation operation of a plastics material preform 10 is preferably begun with a pre-blowing phase PH1 in which the plastics material preform 10 is acted upon with pneumatic medium at low pressure, the so-called preliminary blow moulding pressure. This is followed preferably by a high pressure phase PH2, in which the plastics material preforms 10 are inflated to form plastics material containers 20 by acting upon pneumatic medium under (high) pressure. This phase is preferably followed by a low pressure phase PH3, in which preferably at least a part of the pneumatic medium is extracted and is particularly preferably recycled. For example such a pressure reduction in a blow mould in such a phase can be converted into a pressure increase of the pneumatic medium of a further blow mould, as described above. A pressure relief phase PH4 then preferably follows, in which the rest of the pressure prevailing in the blow mould 4 or in the finished inflated plastics material container 20 respectively is relieved.

(26) The high pressure phase preferably always uses a fixed process angle, i.e. the same time period. This is illustrated in FIG. 5 by equal-sized segments of the high pressure phase of the bottle A and B. This may be necessary in order to be able to ensure the quality standards on the shape of the plastics material container 20. For this purpose it is preferably important to achieve the final blow moulding pressure as quickly as possible and to let it remain in the bottle for a long time.

(27) The process sequence illustrated in FIG. 5 for the bottle B shows a longer-lasting pre-blowing phase PH1 by comparison with the bottle A. Reasons for this may possibly be a different container to be expanded, for example a container having a smaller or larger volume. The white segment of the circle diagrams represents the so-called dead angle of the shaping process in the system 1. In this, no more transformations can be carried out on a plastics material preform 10 or on a plastics material container 20 respectively. As already mentioned, this time period represents for example the opening and/or closing of the blow mould 42 and/or the delivery of a plastics material preform 10 into the system 1 and/or the removal of the finished blown plastics material container 20 from the system. This time period is preferably substantially fixed with respect to its duration. It may now be preferable, in the case of a pre-blowing phase PH1 which starts early, to delay the pressure relief phase PH4 for as long as possible and thus, as illustrated in the case of the bottle A, to lengthen the low pressure phase PH3 by comparison with the bottle B.

(28) In a preferred embodiment the pressure reduction inside a first blow mould 42, which is particularly preferably in the low pressure phase, is coupled at the same time to the pressure reduction of a pneumatic medium inside a further blow mould 42 which is preferably in the pre-blowing phase. Since with such a design the final blow moulding time of the first blow mould 42 also determines the time of the pressure reduction and nevertheless as far as possible the entire process angle should be used for cooling the bottle, the bottle is still kept at a low pressure level until the final venting.

(29) FIG. 6 shows a schematic representation of the embodiment illustrated in FIG. 1 of a system according to the invention, identifying the individual phases in which the plastics material containers are undergoing their transforming operation. The blow moulding station designated by x is still in the pre-blowing phase PH1, i.e. the plastics material preform 10 has already been acted upon with pneumatic medium at low pressure, the so-called preliminary blow moulding pressure. By acting upon pneumatic high-pressure medium, the plastics material preform 10 is inflated in the high pressure phase PH2 to form a plastics material container 20. Finally the pressure of the pneumatic medium is reduced, so that the blow moulding station 4 is in the low pressure phase PH3 (blow moulding station 4, designated by x-n). To conclude, the remaining pressure is reduced, which corresponds to the pressure relief phase PH4.

(30) The energy conversion device 86 can now be coupled to the blow moulding station x by means of a distributor star as illustrated in FIG. 4 or by means of the pressure supply device 6 respectively, in order to act upon the container with pressure there and to decouple it again from the blow moulding station x and to associate the energy conversion device 86 with a blow moulding station x-n in order to reduce the pressure there again. In this case the number n is the number of blow moulding stations in the high pressure phase. Thus in the example illustrated in FIG. 6 n would be equal to 4. If m describes the number of energy conversion devices 86 of the system 1, then the above energy conversion device 86 is connected to the x+1*m-th blow moulding station 4 in which pressure is built up and finally the pressure is relieved in the xn+1*m-th blow moulding station.

(31) In an alternatively embodiment (for example use of a second compression cylinder 7) pressure can be simultaneously built up and relieved in the blow moulding stations x and x-n.

(32) FIG. 7 shows a schematic cross-sectional representation of a compression cylinder 7 of a further preferred embodiment of a system 1 according to the invention. In a compression cylinder 7 configured in this way the piston has a piston surface K0 for pretensioning. This is located on the pretensioning side S0. On the other side, the compression side S1, the piston surface is not in one piece but is subdivided into three piston part-surfaces K1-K3. This produces three separate part-chambers R1-R3, in which both individually and also in conjunction with one or both other part-chambers can be used for compression of a pneumatic medium. Moreover, the part-chambers R1-R3 can also be individually atmospherically ventilated.

(33) An axis A is also shown, which runs through the piston rod and parallel to the direction of movement of the piston rod. With respect to this axis there are two part-chambers R1, R2 and also the two associated piston part-surfaces K1, K2 spaced further therefrom than the third part-chamber R3 or the associated piston part-surface K3. K1 and K2 can be formed as annular surfaces and K3 can be formed as a circular surface.

(34) FIG. 8 shows a schematic cross-sectional representation of a further embodiment of an energy conversion device 86, which has a compression cylinder 7 coupled to a crank mechanism. The compression cylinder 7 has a chamber for compression of a pneumatic medium, the compression side S1, as well as a chamber for pretensioning, the pretensioning side S0. The pretensioning serves as an energy store for potential energy and can also serve as a drive, the pressure level being varied in the forward and return stroke. The energy released at the beginning in a compression operation as a result of the excess force of the pretension should be stored intermediately by conversion into kinematic energy. Since this amount of energy is enormous and at the same time the piston speed is limited, a coupling of the piston to an oscillating weight 12 is provided. Due to the continuing transmission in the dead centre the piston can be held in its end position with only a low force. A drive can be provided both by changing the preload pressure and also pneumatically or hydraulically. An additional electrical drive 122 on the oscillating weight 12 is initially provided for keeping the oscillating weight in the end positions of the piston, but can also be used as an auxiliary drive or as a main drive.

(35) FIG. 9 shows a qualitative diagram to illustrate the piston force depending from the piston positions in the event of a mechanically coupling of a compression cylinder with a crank mechanism. In this case L1 constitutes the opposing force for a forward stroke and L2 constitutes the opposing force for a return stroke. Finally, L3 shows the dependence of the piston force in the case of a forward stroke without pretension and L4 shows the piston force in the case of a return stroke without pretension.

(36) FIG. 10 shows a schematic cross-sectional representation of a compression cylinder 7. The illustrated compression cylinder 7 has four chambers Ra, Rb, Rc and Rd. In this case the respective piston surfaces A1, A2, A3 and A4 are all mechanically connected to the piston rod 72, which can be driven by means of a drive. Pneumatically medium can be delivered to the first chamber Ra for example by means of a pressure extraction device 8, which extracts the pneumatic medium used for expansion from a finally blow moulded plastics material container 20. Such a delivery preferably takes place during a piston return stroke. During a piston return stroke the piston moves towards the left in the drawing plane. Accordingly during a piston return stroke in each case the volume of the second chamber Rb and of the fourth chamber Rd is decreased. Simultaneously the volume of the first chamber Ra and of the third chamber Rc is increased. The drawing also shows a fluid communication between the first chamber Ra and the second chamber Rb, a fluid communication between the second chamber Rb and the third chamber Rc, which may be provided with a non-return valve 76, as well as a fluid communication between the third chamber Rc and the fourth chamber Rd. An outlet conduit 78, by means of which pneumatic medium located in the fourth chamber Rd can be extracted and which can likewise be provided with a non-return valve 76, can preferably be arranged at a removal point on the fourth chamber Rd.

(37) Moreover it is shown in FIG. 10 that the piston surfaces A1-A4 preferably have surfaces of different sizes. It is shown that the chamber Ra has the greatest piston surface A1, the chamber Rb has the second greatest piston surface A2, the chamber Rc has the third-largest piston surface A3 and the chamber Rd has the smallest piston surface A4.

(38) In a preferred method in the first compression stage of the compression cylinder 7 in a piston return stroke of the first chamber Ra pneumatic medium is delivered and then the delivery connection is disconnected. Then a fluid communication is preferably produced between the first chamber Ra and the second chamber Rb. Therefore in the event of a piston forward stroke (movement of the piston to the right in the drawing plane) the pneumatic medium located in the first chamber Ra is preferably pushed into the second chamber Rb and is thereby compressed to an intermediate pressure level. After the end of the piston forward stroke, the fluid communication between the first chamber Ra and the second chamber Rb is disconnected again.

(39) In the second compression stage of the compression cylinder 7, a piston return stroke and a subsequent piston forward stroke take place. In this case during the piston return stroke a fluid communication between the second chamber Rb and the third chamber Rc is produced, so that the pneumatic medium located in the second chamber Rb is pushed into the third chamber Rc. At the end of the piston return stroke, the fluid communication between the second chamber Rb and the third chamber Rc is interrupted again. In the subsequent piston forward stroke a fluid communication is produced between the third chamber Rc and the fourth chamber Rd, so that the piston surface A3 of the third chamber Rc allows the pneumatic medium located therein to flow through the produced fluid communication into the fourth chamber Rd. After termination of the piston forward stroke this fluid communication is also disconnected again. Then the pneumatic medium, which is now compressed for the second time and is located in the fourth chamber Rd, can be extracted for example by means of the outlet conduit 78.

(40) FIGS. 11-14 show illustrations of different preferred embodiments of a method for recycling a pneumatic medium used for reshaping. In the different embodiments of the method. Individual main steps are designated by numbers placed in boxes and method steps which proceed in an analogous or similar manner respectively are designated by the same numbers. It is pointed out that subsequent numerical examples are offered merely by way of example and in each case merely constitute a preferred application of the method.

(41) FIG. 11 shows a preferred embodiment of a first embodiment of the method for recycling a pneumatic medium used for reshaping without the participation of an intermediate pressure reservoir and with a high pressure compressor according to one example.

(42) In this case after the final blow moulding of a bottle 21 (for example a plastics material container 20) in a first step (decompression) a pressure of 30 bar from the bottle is decompressed to a first pressure level, in this case 5 bar. Such a decompression is achieved by the production of a fluid communication between the bottle 21 and a chamber R. In the illustration the chamber is the chamber of a compression cylinder 7. With a capacity of the bottle 21 of for example 1.6 liters, after the decompression this is a total of 5.75 liters at 5 bar. After the termination of the decompression the fluid communication is disconnected again. Then 4.15 liters of pneumatic medium are located in the chamber R under a pressure of 5 bar.

(43) In a second step (decompression) the pneumatic medium located in the chamber R is compressed until a second pressure level is reached, which in this case is 30 bar. Due to the compression to 30 bar the volume of the pneumatic medium is reduced to 1.13 liters.

(44) In a third step (diversion) the medium (which is located in the chamber R) compressed to the second pressure level (in this case 30 bar) is delivered to a further blow mould 42 and in this case is diverted into the next bottle 22. The next bottle 22 may also be a plastics material preform to be expanded. Thus the proportion of this pneumatic high-pressure medium of the next bottle 22, which is obtained from intrinsic compression, amounts to 1.13 liters. The so-called next bottle 22 has (in its expanded state) a capacity of 1.6 liters. Thus the 1.13 liters of pneumatic medium obtained from intrinsic compression are not sufficient at 30 bar. A further 0.47 liters of pneumatic high-pressure medium is still necessary in order to inflate the illustrated bottle 22, that is to say preferably a plastics material preform 10, to its final form (of a plastics material container 20).

(45) This additionally required, residual pneumatic medium below 30 bars is topped up in a fourth step by a high pressure compressor 170. Due to the proportion from the high pressure compressor 170, overall the volume (in this case 1.6 liters) of pneumatic high-pressure medium (at 30 bar) which is necessary for a processing operation (such as expanding a plastics material preform) is obtained.

(46) Preferably, through the delivery of the volume of pneumatic high-pressure medium, which is sufficient for an expansion of a plastics material preform 10 to form a plastics material container 20, into a further plastics material preform 10 this preform is transformed or expanded respectively into a plastics material container 20. After this final blow moulding this method can be applied again and thus can be started again with the first step.

(47) FIG. 12 shows an illustration of a preferred embodiment of a second preferred variant of the method for recycling a pneumatic medium used for reshaping without involving an intermediate pressure reservoir and with a low pressure compressor. Similarly to the first embodiment of a method just described, in a first step (decompression) 30 bar from a finally blow moulded bottle 21 (with a capacity of 1.6 liters) are decompressed to 5 bar by a fluidic connection to a chamber R. After interruption of this fluid communication, here too 4.15 liters of a pneumatic medium at 5 bar are obtained in the chamber R.

(48) In contrast to the previously described embodiment of a method, before the second step (compression) additional pneumatic medium is now delivered to the chamber R. This delivered pneumatic medium is provided by a low pressure compressor 172 and preferably constitutes the so-called residual volume. This residual volume is the pneumatic medium required in addition to the recovered volume, so that after suitable pressure transformation of the total volume (that is to say recovered and additionally delivered pneumatic medium) a plastics material preform 10 can be inflated to a plastics material container 20 by the resulting pneumatic high-pressure medium. In the example set out here, 1.7 liters of pneumatic medium at 5 bar are delivered to the chamber R, so that the chamber then contains 5.85 liters at 5 bar.

(49) Subsequently the second step proceeds as in the previously described embodiment of the method. The pneumatic medium located in the chamber R is compressed to 30 bar by a compression cylinder 7. The resulting volume then amounts to 1.6 liters and thus corresponds precisely to the volume which is required for expansion of a further plastics material preform 10.

(50) In the third step this pneumatic high-pressure medium generated by intrinsic compression from the chamber R is diverted into the next bottle 22 (or a further plastics material preform 10 or further blow mould 42 respectively).

(51) In the embodiment of the method described here the fourth step of the previously described variant of the method is omitted.

(52) After the final blow moulding, here too it is possible to start again with the first step.

(53) FIG. 13 shows an illustration of a preferred third variant of the method for recycling a pneumatic medium used for reshaping with the involvement of an intermediate pressure reservoir and with a high pressure compressor. The four steps of the first variant of the method described with regard to FIG. 11 proceed in principle.

(54) This variant of the method differs in that initially the finally blow moulded bottle 21 (again 1.6 liters capacity) is fluidically connected to an intermediate pressure reservoir in which 15 bar preferably prevail. As a result the pressure in the bottle 21 reduces from initial 30 bar likewise to 15 bar.

(55) Then, starting from a bottle 21 filled with pressure medium at 15 bar the first step (decompression) known from the first embodiment of the method is implemented. In this connection the bottle is fluidically connected to a chamber R and decompressed to 5 bar. As A result in the chamber R a volume of 1.9 liters of pneumatic medium at 5 bar is obtained.

(56) In the subsequent second step (compression) this pneumatic medium located in the chamber R is compressed to 30 bar by a compression cylinder 7. As a result the volume of the pneumatic high pressure medium (at 30 bar) recovered by means of intrinsic compression is reduced to 0.52 liters.

(57) In a third step this volume of pneumatic high-pressure medium recovered by means of intrinsic compression is now delivered to a further bottle 22. In contrast to the first variant of the method, however, this is not an empty container with an internal pressure of approximately 1 bar, but this bottle 22 has already been pre-filled with pneumatic medium, for example from the intermediate pressure reservoir. Thus the bottle 22 already has an internal pressure of 15 bar. This preliminary filling corresponds to a volume of 0.68 liters at a pressure of 30 bar.

(58) After delivery of the recovered pneumatic high-pressure medium from the chamber R, in the fourth step residual volume at 30 bars is now delivered by a high pressure compressor 170. In this case the high pressure compressor supplements the material amount of pneumatic medium delivered to the next bottle 22 by the volume which is required for example for inflating a plastics material preform 10 to a plastics material container 20.

(59) Thus overall the pneumatic medium delivered to the bottle 22 is made up of three proportions. A proportion of 0.68 liters at 30 bar results from the preliminary filling, a further proportion of 0.52 liters at 30 bar results from the pneumatic high-pressure medium recovered by intrinsic compression and a further proportion results from the delivery of the residual volume by the high pressure compressor 170, which as a whole produces a (necessary) volume of 1.6 liters at 30 bar.

(60) FIG. 14 shows an illustration of a preferred fourth embodiment of a method for recycling a pneumatic medium used for reshaping with the involvement of an intermediate pressure reservoir and with a low pressure compressor. Here, just as in the previously described third embodiment of the method the bottle 21 is initially connected to an intermediate pressure reservoir and as a result the internal pressure thereof is decompressed from initial 30 bar to 15 bar. Then the first step of pressure relief takes place in a chamber R to 5 bar. As already described in the embodiment of the method in FIG. 12, before the compression in a third step additional pneumatic medium is added to the chamber R.

(61) This pneumatic medium has a pressure of 5 bar and is provided by a low pressure compressor 172. As already mentioned, in this way a corresponding volume difference (adapted appropriately to the pressure) is provided, which would be absent after compression to 30 bar for the necessary or required volume respectively of pneumatic high-pressure medium at 30 bar. In this case a volume of 1.45 liters of pneumatic medium at 5 bar are provided by the low pressure compressor 172 and delivered to the chamber R. Then in the second step a compression of the pneumatic medium located in the chamber R to 30 bar takes place, so that the volume thereof is reduced to 0.92 liters. This is diverted into an already pre-filled next bottle 22, as in the previously described variant of the method (FIG. 13). Here too, such a preliminary filling can take place by feeding in pneumatic medium from an intermediate pressure reservoir. The internal pressure of the pre-filled bottle 22 illustrated in FIG. 14 amounts to 15 bar. The total volume of pneumatic medium delivered to the next bottle 22 (at 30 bar) is made up of a proportion from the intrinsic compression of 0.92 liters (compression of the pneumatic medium in the chamber R) and of the pneumatic medium from the preliminary filling of the bottle 22, which at a pressure of 30 bar corresponds to a volume of 0.68 liters.

(62) The applicant reserves the right to claim all the features disclosed in the application documents as essential to the invention in so far as they are individually or in combination novel over the prior art. Furthermore it is pointed out that in the individual drawings features were also described which may be advantageous per se. The person skilled in the art recognises immediately that a specific feature described in a drawing may also be advantageous without the incorporation of further features from this drawing. Furthermore the person skilled in the art recognises that advantages may also result from a combination of several features shown in individual drawings or in different drawings.

LIST OF REFERENCES

(63) 1 system

(64) 2 carrier

(65) 4 blow moulding station

(66) 6 pressure supply device

(67) 7 compression cylinder

(68) 8 pressure extraction device

(69) 9 hydraulic cylinder

(70) 10 plastics material preform

(71) 12 oscillating weight

(72) 20 plastics material container

(73) 21 bottle

(74) 22 next bottle

(75) 42 blow mould

(76) 66 intermediate energy storage device

(77) 70 distribution device

(78) 72 piston rod

(79) 74 compression piston

(80) 76 non-return valve

(81) 78 outlet conduit

(82) 86 energy conversion device

(83) 92 fillable chamber for stroke adjustment

(84) 94 hydraulic drive

(85) 122 driving device

(86) 170 high pressure compressor

(87) 172 low pressure compressor

(88) A axis

(89) A1-A4 piston surfaces

(90) F force

(91) G1 graph for expansion operation

(92) G2 graph for compression operation

(93) K0 piston surface for pretensioning

(94) K1 piston part-surface 1

(95) K2 piston part-surface 2

(96) K3 piston part-surface 3

(97) L1 opposing force forward

(98) L2 opposing force return

(99) L3 piston force forward without pretension

(100) L4 piston force return without pretension

(101) P1 arrow 1

(102) P2 arrow 2

(103) PH1 pre-blowing phase

(104) PH2 high pressure phase

(105) PH3 low pressure phase

(106) PH4 pressure relief phase

(107) R0 chamber (on the piston rod side)

(108) R chamber

(109) R1 part-chamber 1

(110) R2 part-chamber 2

(111) R3 part-chamber 3

(112) Ra-Rd chambers of a compression cylinder 7

(113) s piston position

(114) S0 pretensioning side (pretensioning chamber)

(115) S1 compression side (compression chamber)

Key to Drawings

(116) FIG. 11:

(117) Nach Fertigblasen=after final blow moulding

(118) Nach Entspannung: insgesamt 5.75 l bei 5 bar=after decompression: total 5.75 liters at 5 bar

(119) Entspannen=decompression

(120) Komprimieren=compression

(121) Umleiten der Luft in die nchste Flasche=diversion of the air into the next bottle

(122) Rest aufgefllt durch Hochdruckkompressor=remainder topped up by high pressure compressor

(123) Anteil Eigenkompressor=Proportion internal compressor

(124) Anteil Kompr.=Proportion comp.

(125) Hochdruckkompressor=high pressure compressor

(126) Befllen der nchsten 1.6 l Flasche=filling of next 1.6 liter bottle

(127) Komplett befllt=completely filled

(128) Ergebnis=result

(129) Wiederbeginn bei 1.)=tart again at 1.)

(130) FIG. 12:

(131) Nach Fertigblasen=after final blow moulding

(132) Nach Entspannen: insgesamt 5.75 l bei 5 bar=after decompression: total 5.75 liters at 5 bars

(133) Entspannen=decompression

(134) Niederdruck-Kompressor=low pressure compressor

(135) Restvolumen aus Niederdruckkompressor=residual volume from low pressure compressor

(136) Komprimieren=compression

(137) Umleiten der Luft in die nchste Flasche=diversion of the air into the next bottle

(138) Ergebnis=result

(139) Wiederbeginn bei 1.)=start again at 1.)

(140) FIG. 13:

(141) Nach Fertigblasen=after final blow moulding

(142) Nach Entspannen: insgesamt 3.5 l bei 5 bar=after decompression: total 3.5 liters at 5 bar

(143) Entspannen=decompression

(144) Komprimieren=compression

(145) Befllen der nchsten Flasche=filling the next bottle

(146) leer=empty

(147) entspricht=corresponds to

(148) Anteil aus Eigenkompressor hinzugefgt=proportion from internal compressor added

(149) Rest aus Hochdruckkompressor=residue from high pressure compressor

(150) Anteil Eigenkompressor=proportion internal compressor

(151) Anteil Kompr.=proportion comp.

(152) Ergebnis=result

(153) Hochdruckkompressor=high pressure compressor

(154) Wiederbeginn bei 1).=start again at 1).

(155) FIG. 14:

(156) Nach Fertigblasen=after final blow moulding

(157) Nach Entspannen: insgesamt 3.5 l bei 5 bar=after decompression: total 3.5 liters at 5 bar

(158) Entspannen=decompression

(159) Niederdruck-Kompressor=low pressure compressor

(160) Restvolumen aus Niederdruckkompressor=residual volume from low pressure compressor

(161) Komprimieren=compression

(162) Befllen der nchsten Flasche=filling the next bottle leer=empty

(163) entspricht=corresponds to

(164) Anteil aus Eigenkompressor hinzugefgt=proportion from internal compressor added

(165) Anteil Eigenkompressor=proportion internal compressor

(166) Ergebnis=result

(167) Wiederbeginn bei 1).=start again at 1).