WO2002067657A1

WO2002067657A1 - A bailing press

Info

Publication number: WO2002067657A1
Application number: PCT/DK2002/000104
Authority: WO
Inventors: Thomas Koch; Ulrik W. Knudsen
Original assignee: Tk Energi As
Priority date: 2001-02-14
Filing date: 2002-02-14
Publication date: 2002-09-06
Also published as: DK200100242A; DK174162B1

Abstract

A baling press serving for compressing a biomass, such as e.g. straw, into bales (17, 18). The baling press (1) comprises a pressing chamber (2) defined by a number of walls (5, 6) and having mainly flushing front and rear openings (9, 10), a press ram (13) located at the front opening (9) of the pressing chamber (2) for compressing biomass in the pressing chamber (2) into bales (17, 18) during repeating strokes in a direction from the front to the rear opening (9, 10) and pushing these bales out of the rear opening (10), mountings (7) for movable mounting of at least one of the walls of the pressing chamber (2), at least one pressure fluid cylinder (8) for moving the at least one chamber wall (6), and a driving arrangement (3) for displacing the press ram (13) in a reciprocating manner during operation. The driving arrangement (3) comprises at least one knee joint (11) operatively connected to the press ram (13) and a fixed part (12= on the baling press respectively, and at least one second pressure fluid cylinder (15) for actuating the knee joint. The baling press has a simple and inexpensive structure, a fast working operating cycle and is further more able to optimally compress biomasses of different structures to desired density.

Description

A baling press

The invention relates to a baling press for compressing a biomass, such as e.g. straw, into bales and comprising a pressing chamber defined by a number of walls and having mainly flushing front and rear openings, a press ram located at the front opening of the pressing chamber for compressing biomass in the pressing chamber into bales during repeating strokes in a direction from the front - to the rear opening and pushing these bales out of the rear opening, mountings for movable mounting of at least one of the walls of the pressing chamber, at least one pressure fluid cylinder for moving the at least one chamber wall, and a driving arrangement for reciprocating displacement of the press ram during operation.

During a stroke of the press ram, a portion of loose biomass is compressed to desired density with successively increasing force application.

In some known baling presses, the ram is driven by one or more hydraulic cylinders which for exactly this purpose however have the disadvantage of the ram during the entire ram stroke moving mainly at the same rate and being made to exert the same great force application during this as at the end of the stroke. The dimensions of the driving arrangement will therefore be relatively large and the known baling presses correspondingly expensive and slow working.

In other known baling presses, the ram is driven by a power takeoff from e.g. a tractor via a gearing, an axle, a crank, and a connecting rod. The arrangement is complicated and expensive and badly suited for optimally compressing biomasses of different structures.

The object of the invention is to provide a baling press of the kind mentioned in the opening paragraph, that has a simple and inexpensive structure, a fast working operating cycle, and furthermore is able to optimally compress biomasses of different structures to a desired density.

The novel and unique features according to the invention, whereby this is achieved, is the fact that the driving arrangement comprises at least one knee joint operatively connected to the press ram and a fixed part on the baling press respectively, and at least one second pressure fluid cylinder for actuating the knee joint.

Thereby, the advantage is obtained in that the ram during a ram stroke at first is displaced at a relatively great speed under the exertion of a relatively small force application on the biomass and at the end is displaced at a relatively low speed under the exertion of a relatively great force application on the biomass.

This work pattern suits the nature of the biomass well. In loose state, the biomass takes up much room, and only modest force is required to give the biomass a relatively great change in volume. At the beginning, the forces that the driving arrangement might exert thus only increase slowly with the travel of the ram. As the biomass is compressed, ever increasing forces are however required to give the biomass ever smaller changes in volume. In the terminal phase, the forces exerted by the driving arrangement thus increase intensely with the travel of the ram.

The above mentioned advantageous mode of working of the knee joint results in the fact that the driving arrangement according to the invention obtains a simple and inexpensive structure and can operate at high production rates during operation. In an advantageous embodiment, the baling press can comprise a first - and a second pump for putting the at least one first - and at least one second cylinder under a first and second fluid pressure respectively, and a fluid control circuit arranged to reduce the first fluid pressure sufficiently to make the ram displace the biomass and the bales in the pressing chamber when the second fluid pressure has reached a set value sufficient to make the ram compress the biomass into bales of desired density. This arrangement results in the fact that the driving arrangement is able to compress different biomasses optimally.

A regulating valve can furthermore be inserted in the control circuit for setting the set value such that it suits exactly the type of biomass to be compressed into bales at a given moment .

In practice, the driving arrangement can comprise four knee joints located in pairs mirror-inverted about a bisector and in straightened state extending mainly parallel to the direction of displacement of the ram whereby the knee joints outweigh each other and obtain an advantageous working position.

In an especially advantageous embodiment, the control circuit can furthermore comprise a flow divider for ensuring that the pressure fluid cylinders at a given moment are supplied with pressure fluid at the same volume and pressure. Thereby, it is obtained that the knee joints can operate without lateral guidance .

In an advantageous second embodiment, the baling press can comprise transverse guides designed in the walls of the pressing chamber, and teeth that in a displaceable manner are received in the guides, and means for displacing the teeth between a first position in which the teeth are extending into the pressing chamber and a second position in which they are free of this chamber.

When the biomass is compressed up against these teeth in their first position, the back pressure increases more steeply towards the end of a ram stroke than is the case when the back pressure is established by the friction between the walls and the biomass/bales, which is acting more evenly during the entire travel. As the work is the product of the ram force and the length of stroke, the effort used to produce the bales is therefore advantageously reduced where the second embodiment of the baling press is employed instead of the first one.

When the teeth are drawn free of the chamber, the bales can furthermore be displaced along the pressing chamber with a minimum of energy consumption.

The invention will be explained in greater detail below, describing only exemplary embodiments with reference to the drawing, in which

Fig. 1 is a diagrammatic longitudinal side cross section of a fragment of a baling press with a driving arrangement according to the invention in a first operation phase,

Fig. 2 is the view in fig. 1 in a terminal phase,

Fig. 3 is a diagram of a fluid control circuit for controlling the baling press,

Fig. 4 is a diagram of the ram force, hydraulic cylinder force and density of the biomass in dependence of the travel of the ram,

Fig. 5 shows a second embodiment of a baling press according to the invention during compressing of the biomass into bales, Fig. 6 is the view in fig. 5 but during displacement of the bales, and

Fig. 7 is a diagram of the work used for compressing a bale where the first and second embodiment of the baling press respectively are employed.

Conventionally, baling presses are provided with wheels and arranged to drive or be driven across a field and collect biomass which is compressed into bales. However, there are also stationary baling presses for compressing biomass transported in from afar into bales . The driving arrangement according to the invention can advantageously be employed for both these types of baling presses.

In the following description, it is assumed that the biomass is straw and that the driving arrangement is driven hydraulically .

The main components of the baling press shown diagrammatically in figs. 1-2 are a pressing chamber 2, a driving arrangement 3, and a hopper 4. In the case shown, the pressing chamber 2 is rectangular and defined by four walls, of which only the bottom one 5 and top one 6 are shown.

The bottom wall 5 is fixed whereas the top wall 6 can pivot about a hinge 7 under the influence of one or more hydraulic counter pressure cylinders 8. The two side walls (not shown) can also pivot about hinges (not shown) under the influence of one or more other hydraulic counter pressure cylinders (not shown) .

The pressing chamber 2 has a front opening 9 and a rear opening 10. The driving arrangement 3 is located at the front opening and consists of four knee joints 11 journaled on a fixed part 12 of the baling press 1 at one end and at the other end on a ram 13 located in a displaceable manner in the pressing chamber 2.

At their centre bearing 14, the four knee joints 11 are connected to each their hydraulic pressing cylinder 15 each pivotally connected to the baling press at the other end.

During operation, loose straw 16 is fed via the hopper 4 in batches down into the pressing chamber 2 in the area at the ram 15 which, by means of an adequate number of ram strokes, for example 20 - 25 of a duration of e.g. 5 - 15 sec, is compressing the straw into bales 17 and 18.

In the case shown, the pressing chamber is sufficiently long to completely or partly contain both a finished bale 17 and an unfinished bale 18. In other cases, the pressing chamber can be arranged to contain several bales .

During a ram stroke, the ram 15 is pressing the unfinished bale 18 up against the already finished bale 17 which thereby provides the back pressure required by the compressing process .

This back pressure determines the compactness of the straw and is regulated by the hydraulic counter pressure cylinders 8 which are keeping the pivotal chamber walls pressed in against the bales which thereby are influenced by the friction which is produced by the walls against the bales and depends on the pressure in the counter pressure cylinders .

However, it is not enough that the ram is able to thus compress the straw to the desired density. It must also be able to push the bales out through the rear opening 10 of the pressing chamber. When the straw has obtained the desired density during a ram stroke, the oil pressure in the hydraulic counter pressure cylinders is therefore reduced sufficiently to allow the ram to move the bales a distance in the pressing chamber.

To control this process, the baling press is provided with the control circuit in fig. 3 comprising a pressing pump 19 for supplying oil under pressure via a first set of oil pipes 20 to the hydraulic pressing cylinders 15 of the knee joints 11, and a back pressure pump 21 for supplying oil under pressure via a second set of oil pipes 22 to the hydraulic counter pressure cylinders of the pivotal chamber walls.

Further, the control circuit comprises a control valve 23 in the first set of oil pipes 20 and a regulating valve 24 in the second set of oil pipes 22. The two valves 23, 24 are interconnected with a control line 25 allowing the regulating valve 24 to register the oil pressure in the pressing cylinders 15.

The control circuit is functioning in the following way.

A detector (not shown) registers if there is sufficient loose straw in the pressing chamber to justify a ram stroke. If this turns out to be the case, the detector signals the control valve 23 which now turns on pressure oil from the pressing pump 19 to the hydraulic cylinders 15 which then begin to straighten the knee joints 3 out so that the ram 13 will begin travelling in the direction from the front opening 9 of the pressing chamber 2 to the rear opening 10.

The force which the knee joint is able to exert at first is relatively modest but on the other hand the resistance offered by the loose straw against being compressed into a smaller volume is correspondingly modest. The finished bale 17 is standing still in the pressing chamber and supplies the necessary back pressure to the unfinished bale 18 during this.

Fig. 4 is a diagram showing, in dependence of the travel of the ram 13, in full line the ram force in kN, in broken line the hydraulic cylinder force in kN and in dash-dot line the density kg/m³ of the straw.

As can be seen, the ram force is at first only increasing slightly with the travel of the ram. When the ram has reached a position of about 600 mm, the knee joints 11 have however been straightened more out and are therefore affecting the ram with greater force while the hydraulic pressing cylinders 13 have reached their maximum capacity of about 225 kN with a corresponding maximum oil pressure in the pressing cylinders of e.g. 250 bars. The process will therefore die unless the finished straw bale 17 is displaced in a direction away from the ram to thereby give the knee joint the chance of straightening further out so that the ram force can be increased even though the oil pressure in the pressing cylinders now has reached its maximum.

At this time, the ram force has only reached a value of about 300 kN, and the straw is only compressed to a density of about 190 kg/m³ while the desired density is about 425 kg/m³.

When the regulating valve 24 via the control line 25 registers the above maximum oil pressure of about 250 bars in the pressing cylinders 13, the regulating valve will reduce the pressure in the counter pressure cylinders 8 to a lower value, e.g. 240 bars.

The pivotal walls of the pressing chamber 24 thereby relieve the pressure on the finished straw bale 17 sufficiently to allow both this bale and the unfinished bale 18 to move a distance. The ram will automatically follow whereby the knee joints 13 will be straightened even more and therefore affect the ram 13 with an even greater force. At the same time, the pressure in the pressing cylinders 15 will drop.

When the regulating valve 24 via the control line 25 registers the reduced oil pressure, the regulating valve 24 will again put the pressure in the counter pressure cylinders 8 up to its former level, e.g. 250 bars. The counter pressure cylinders 8 will thereby press the pivotal walls of the pressing chamber so hard in against the finished straw bale 17 that this again will stand still in the pressing chamber and now is able to offer sufficient back pressure on the unfinished straw bale 18 to ensure that the straw in this bale is compressed at increasing rate of compaction.

The above cycle is now repeated automatically a number of e.g. 20 - 25 times during which the average ram force with increasing ram travel is increasing as shown with the fully drawn curve in fig. 4, and the density will increase as shown with the dotted curve, until the straw has obtained the desired density which in this case is about 425 kg/m³.

On the way the straw bale 17 is bound to finally be pushed out through the rear opening 10 of the pressing chamber 2 after which the now finished straw bale 18 assumes the role as back pressure bale.

The above cycle will proceed with a frequency that can vary in dependence of the structure of the biomass and the controlling of the baling press. Within the scope of the invention, the frequency can go towards zero so that the bales are produced in an approximately evenly sliding motion through the pressing chamber .

Figs. 5 and 6 show a second embodiment of a baling press according to the invention in which back pressure is established by teeth 28 that are received in a displaceable manner in transverse guides 29 designed at least in the walls 5 and 6. In the case shown, there are two guides respectively having two teeth for each of the walls 5 and 6, the number being able to be of any suitable size within the scope of the invention.

The teeth are mounted on bars 30 which, by means of hydraulic cylinders 31, can displace the teeth between a first position in which they are extending into the pressing chamber 2 and a second position in which they are free of this chamber.

In fig. 5, the teeth 28 are in their first position in which they are extending into the pressing chamber and locking the bales 17 and 18 which thereby are made able to provide the back pressure required to compress the biomass.

The biomass/bales are compressed up against the teeth whereby the back pressure will increase more steeply towards the end of the stroke than if the back pressure, as in the first embodiment, was provided by the frictional forces acting more evenly during the entire ram stroke.

The curves 32 and 33 shown in the diagram in fig. 7 illustrate the compression force as a function of the ram travel where the first and second embodiment respectively of the baling press are employed. The work used for compressing the straw is a product of the force and the travel and is the area shown under the curves 32 and 33 respectively. The work saved by employing the second embodiment instead of the first is the hatched area between the curves .

In fig. 6, the teeth 28 are drawn out of the walls 5 and 6.

The bales 17 and 18 will therefore meet practically no resistance when they are displaced along the pressing chamber at the end of a stroke to finally be pushed out through the rear opening 10 of the pressing chamber 2. During this part of the process, the energy consumption is therefore minimal.

As mentioned previously, the driving arrangement of the baling press comprises in the case shown four knee joints 11 actuated by each their hydraulic pressing 15 during operation. The four pressing cylinders 15 are supplied with oil of the same volume and pressure during operation by means of a flow divider 26 inserted in the control circuit in fig. 4 between the control valve 23 and the four pressing cylinders 15. The driving arrangement is therefore advantageously made able to function without lateral guidance so that the baling press will obtain a simple and reliable structure.

The flow divider 26 shown consists of four small oil pumps 27 located on a joint shaft and thereby ensuring a uniform flow in all oil pipings to the pressing cylinders.

Claims

Patent claims

1. A baling press for compressing a biomass, such as e.g. straw, into bales (17; 18) and comprising a pressing chamber (2) defined by a number of walls (5; 6) and having mainly flushing front and rear openings (9,-10), a press ram (13) located at the front opening (9) of the pressing chamber (2) for compressing biomass in the pressing chamber (2) into bales (17; 18) during repeating strokes in a direction from the front - to the rear opening (9,-10) and pushing these bales out of the rear opening (10) , mountings (7) for movable mounting of at least one of the walls of the pressing chamber (2) , at least one pressure fluid cylinder (8) for moving the at least one chamber wall (6) , and a driving arrangement (3) for reciprocating displacement of the press ram (13) during operation, characterised in that the driving arrangement (3) comprises at least one knee joint (11) operatively connected to the press ram (13) and a fixed part (12) on the baling press respectively, and at least one second pressure fluid cylinder (15) for actuating the knee joint.

2. A baling press according to claim 1, characterised in that the baling press (1) comprises a first - and second pump (21; 19) for putting the at least one first - and at least one second cylinder (8; 15) under a first and second fluid pressure respectively, and a fluid control circuit arranged to reduce the first fluid pressure sufficiently to make the ram (13) displace the biomass and the bales (17; 18) in the pressing chamber

(2) when the second fluid pressure has reached such a set value which is sufficient to make the ram (13) compress the biomass into bales (17; 18) of desired density.

3. A baling press according to claim 2, characterised in that the control circuit comprises a regulating valve (24) for setting the set value.

4. A baling press according to claim 1, 2 and 3, characterised in that the baling press comprises four knee joints (11) located in pairs mirror-inverted about a bisector and in straightened state extending mainly parallel to the direction of displacement of the ram (13) and one for each knee joint (11) associated second pressure fluid cylinder (15) .

5. A baling press according to claim 4, characterised in that the control circuit comprises a flow divider (26) for ensuring that the four other pressure fluid cylinders (15) at a given moment are provided with pressure fluid of the same volume and pressure.

6. A baling press according to any of the claims 1 - 5, characterised in that the baling press comprises at least one transverse guide (29) designed in at least one of the walls (5; 6) of the pressing chamber, a tooth (29) received in a displaceable manner in the at least one guide (29) , and means (30; 31) for displacing the tooth (28) between a first position in which it is extending a distance into the pressing chamber (2) and a second position in which it is free of this chamber .