DE102009026604A1 - Hydraulic cylinder assembly for a machine for producing a fibrous web, in particular a paper or board machine - Google Patents

Abstract

The invention relates to a hydraulic cylinder assembly for a machine for producing a fibrous web, in particular a paper or board machine. The assembly has a hydraulic cylinder including a cylinder housing and a piston movable in the cylinder housing dividing the cylinder housing into a cylinder head side chamber and a cylinder bottom chamber, and at least one digital hydraulic pressure regulator integrated into the assembly, the cylinder head side chamber and the cylinder head side chamber associated with the cylinder bottom side chamber, and which controls an inflow and outflow of working fluid to and from the chambers to adjust the pressure of the working fluid in at least one of the two chambers of the hydraulic cylinder.

Description

The The invention relates to a hydraulic cylinder assembly for a machine for producing a fibrous web, in particular a paper or board machine.

In Paper machines are widely used as actuating cylinders and control means used. These actuating cylinders are preferred hydraulically driven, allowing great forces adjusted and exercised with high accuracy.

In usually a working fluid, z. As hydraulic oil, air, Water, different gases or emulsions from the previous ones Fluids, etc., used, which is pressurized by a pump becomes. The introduction of the pressurized hydraulic oil in a hydraulic actuator, such. B. a hydraulic cylinder or a hydraulic motor is usually by a proportional control valve (proportional valve) controlled, the can be driven electrically, hydraulically or pneumatically.

One such control valve has a valve housing in a and movable spool or spool, which in response on its location in the valve housing a target pressure on Output can be adjusted by the pressure of the pump supplied by the pump Hydraulic oil is regulated. The mobility of the control piston in the valve housing necessarily requires a certain amount of play or gap between the control piston and valve housing, allowing a leakage of hydraulic oil inside the control valve is inevitable. The gap size must not be too narrow otherwise the valve is too susceptible to contamination in hydraulic oil.

Recently, alternative pressure regulators have been developed which are referred to throughout this application as digital hydraulic pressure regulators. The operation of digital hydraulic pressure regulators is summarized below:
In the simple case, a digital hydraulic pressure regulator consists of a series of valves connected in parallel, which only have an OPEN / CLOSE function; Thus, they are simple ON / OFF switching valves that allow or interrupt fluid flow and are referred to hereafter as valves or digital valves in this application. The valves are all connected to a common supply line on the one hand and to a common outlet line on the other. The valves themselves may be conventional solenoid valves, ie valves with electromagnetic drive. Such electromagnetically actuated valve is z. In EP 1 052 441 A2 described. Of course, other forms of drive can be chosen.

By Connection or installation of throttle elements to the valves or through the design of the valves themselves is ensured that the Valves have different flow rates when open. For example, if four valves are provided, so the flow rates Q in the individual, each of the associated Valve optionally releasable passages in proportion of 1: 2: 4: 8 to each other; at a larger one Number of valves will continue this series accordingly.

By opening and closing individual valves or valve combinations, which is determined and selected on the basis of models from a computer can now be a very fast and accurate pressure adjustment in the outlet line or in the actuator connected thereto be achieved by the analog control curve of the above Proportional valve through a digitally created (ie approximated) Rule curve is replaced. This curve may be due to the omission of Nonlinearities and / or hysteresis loops of the analog Proportional valve a stepped approximated Just be, which allows a control point fast and almost free of overshoot to approach.

One Another advantage of using digital hydraulic pressure regulators is that the valves are either open or closed, d. H. for holding a target pressure in a closed (and thus stationary) system, the valves of the pressure regulator are simple closed and there are no leakage currents inside the valves. This is a clear difference to the conventional one Proportional valve, always by a hydraulic oil flow is flowing through. This constantly costs energy for the hydraulic pumps, z. B. in the paper machine.

Consequently It can be seen that it is the use of digital hydraulic pressure regulators allows the hydraulic pumps less often and / or shorter which saves energy.

It But there is still a need, the energy consumption of a machine for producing a fibrous web, in particular a paper web or board machine, further reduce.

It Therefore, the object of the invention is a hydraulic cylinder assembly for a machine for producing a fibrous web, in particular a paper or board machine, with the energy consumption for hydraulic control of a hydraulic cylinder assembly further reduced for a paper or board machine becomes.

The object of the invention is with a hydraulic cylinder assembly for a machine for producing a fibrous web, in particular a Pa pier or board machine, solved with the features of claim 1.

advantageous Further developments of the assembly according to the invention are set forth in the subclaims.

According to one Aspect of the invention is a hydraulic cylinder assembly for a machine for producing a fibrous web, in particular a paper or board machine provided. The Assembly has a hydraulic cylinder, which is a cylinder housing and a piston movable in the cylinder housing, the cylinder housing in a cylinder head side chamber and a cylinder bottom chamber, and at least one digital hydraulic pressure regulator integrated into the assembly is that of the cylinder head side chamber and the cylinder bottom side Chamber is assigned, and the one inflow and outflow of working fluid to and from the chambers controls to the pressure of the working fluid in to adjust at least one of the two chambers of the hydraulic cylinder.

In the following explanation is always of a paper machine the speech; However, this term is expressly intended to cover all machine types for the production of fibrous webs, thus in particular also cardboard machines, Fiberboard machines and the like.

If a digital hydraulic pressure regulator instead of a conventional one Proportional valve is used, is unchanged Position of the hydraulic cylinder the hydraulic fluid consumption, d. H. the internal leakage current in the controller zero. In a paper machine many adjustable elements are required and available; the Adjustment is not often but only in relatively rare occurring processes, such as starting, web breaks and re-filing the web, reel change or maintenance. The adjusting movements, which are usually connected to the adjusting components in the paper machine attacking hydraulic cylinders be executed, thereby include a movement a hydraulic cylinder and / or possibly a pressure build-up to any mechanical pressure forces, z. B. a pressure in a gap between two rollers to produce.

The Inventors have now found that the cost of providing, Laying and maintenance of pipelines for supply a hydraulic cylinder with working fluid in a conventional Paper machine is considerable. The materials used must be be corrosion-resistant for the moist hot environment, There are enormous distances to tackle, because a usual Paper machine is simply big (several tens of meters long), so that here the material consumption of high quality pipe material is a real cost factor. In addition, there are flow losses in the management of the fluid flows in the lines, either by larger pipe cross-sections, d. H. more material consumption, or by higher pumping power, d. H. through a higher energy consumption, balanced Need to become.

By the assignment of at least one digital hydraulic pressure regulator to the cylinder head side chamber and the cylinder bottom side chamber of the cylinder housing and by the integration of the controller in the hydraulic cylinder assembly can long cable runs omitted and a compact design can be ensured.

Prefers the valves of the digital hydraulic pressure regulator are immediate attached to the hydraulic cylinder or in the piston of the hydraulic cylinder. In these advantageous embodiments of the invention, the valves the digital hydraulic pressure regulator directly to the hydraulic cylinder or mounted in the piston itself. These designs are not only compact, but there are also few hydraulic connection points available. This improves reliability because there are few places in the hydraulic circuit that can leak.

Prefers the piston is a reciprocating piston with piston rod. This piston can be a reciprocating hollow hollow piston Be piston rod, wherein in the piston optionally the valves of the digital hydraulic pressure regulator can be arranged and the hydraulic and electrical wiring of the digital hydraulic pressure regulator through the piston rod through the valves can be guided, reducing the construction the hydraulic cylinder housing can be simplified. Due to the hollow construction of the piston and the piston rod is a additional space for the previously mentioned wiring only then usable, in contrast to a massive piston, which in a solid construction was made. Thus, the available standing space inside the piston and piston rod material optimal for installation of the valves of the hydraulic pressure regulator and the corresponding lines are used. With this design of pistons also ensures that the valves of the hydraulic pressure regulator are installed in the piston such that their outlets directly to the cylinder head side chamber and the cylinder bottom side Chamber of the hydraulic cylinder are assigned, so that the piston rod ultimately occupies a position that is essentially determined by the the pressure regulator set difference of pressures in the cylinder head side chamber and the cylinder bottom chamber of the Hydraulic cylinder depends.

For the valves of the hydraulic pressure regulator can, for. B. 2/2 solenoid valves from Matrix Mechatronics, preferably the 750's Series, to be used.

If the valves of the digital hydraulic pressure regulator immediately attached to the hydraulic cylinder, it is particularly preferred in that the cylinder housing is one to the cylinder head side chamber corresponding prechamber and one to the cylinder bottom side Chamber corresponding prechamber, which are hydraulically separated from each other are and where the valves of the digital hydraulic pressure regulator are directly attached. Furthermore, the two antechambers by a cylindrical housing surrounding the cylinder housing in a fluid-tight manner be formed and corresponding to the cylinder head side chamber Annular space and a corresponding to the cylinder bottom chamber Define annular space, wherein the annular spaces by an intermediate the cylinder housing and the cylinder shell arranged Partition are hydraulically separated from each other and at their peripheral surfaces the valves of the digital hydraulic pressure regulator are attached. Optionally, the cylinder cover and the partition are in one piece formed on the cylinder housing. With this design of the hydraulic cylinder are the outlets of the immediate attached to the hydraulic cylinder (eg on the cylinder cover) Valves of the digital hydraulic pressure regulator to the respective Correspondingly associated with atria. The atria then point a common supply or outlet port on the cylinder housing yourself up. The positions of the common connections the cylinder housing are set such that a position adjustment of the piston within the cylinder by the differently adjustable Press in the atria independent of the respective Location of the piston can be guaranteed. The piston and Thus, the piston rod ultimately take a position in the Essentially of the difference set by the pressure regulators the pressures in the antechamber associated with the cylinder head side chamber and the prechamber associated with the cylinder bottom side chamber depends.

In the above or further embodiments, the digital hydraulic Pressure regulator include a differential pressure control valve, which is a direct hydraulic Connection between the cylinder head side chamber and the cylinder bottom side Chamber switches and a flow of working fluid between the cylinder head side chamber and the cylinder bottom chamber controls. Preferably, the volumes of the cylinder head side Chamber and the cylinder bottom chamber be equal.

According to the The above embodiments of the invention is the hydraulic cylinder a differential cylinder. In a differential cylinder are both on the piston side as well as on the piston rod side pressure-effective Surfaces are formed so that the piston rod of the cylinder ultimately occupies a position that of the on the piston rod acting load and the difference of the pressures on the piston side and the rod side depends. In operation, when the Position of the piston to be adjusted, working fluid under pressure fed into the cylinder chamber, whose volume is to increase, while a corresponding amount of working fluid from the Cylinder chamber is drained, the volume should decrease. In In this case, working fluid is discharged at a pressure level, well above that of a reservoir, hereinafter referred to as tank, lies. This means that the previously invested pumping energy in this part to be drained contained in the working fluid, discharged into the tank unused becomes. By the differential pressure control valve, which is the two chambers the cylinder hydraulically connects to each other, the working fluid flow at high pressure level from one pressure chamber to the other and it may be necessary to apply only the pump energy, which is used to increase the pressure in this volume is required. This saves energy. Furthermore, by using the differential pressure control valve also a simplified construction of the digital hydraulic pressure regulator can be achieved in conjunction with a differential cylinder.

at In the above embodiments, the assembly of the Further comprising an integrated pump to the working fluid with provide sufficient pressure for the digital hydraulic pressure regulator. The pump can be mounted directly on the hydraulic cylinder. Further, the pump can the working fluid at high pressure in a Hydraulically connectable with the digital hydraulic pressure regulator Feed pressure accumulator and apply pressure to it.

In the embodiments shown above, the inventors have found that, with the elimination of the permanent leakage current in proportional control valves, there is actually so little demand for working fluid that it is energetically unfavorable to repeatedly turn on and off a pump of sufficient size for the leakage flow. The inventors have now found that the consumption of working fluid can also be covered by a pressure accumulator, wherein the pressure accumulator is charged with a pump from time to time. For this purpose, it is possible to associate each individual module with its own pressure accumulator and / or its own integrated pump or multiple modules with a common pressure accumulator and / or pump. In the second case, a single pump may be provided to charge the plurality of accumulators. In the case of multiple accumulators can these are also charged one after the other individually, so that a small pump, which can be temporarily integrated into the respective module, which is dimensioned for the corresponding pressure accumulator of the module, is sufficient.

By the assignment of individual accumulators to the individual Assemblies can be a functional and spatial Breakdown of the pressure supply areas, d. H. single local in the assembly integrable pumps are provided, which are independent each other, so that long strands omitted can.

Of Further, with a quick set of digital valves one can digital hydraulic pressure regulator on a pressure accumulator the pressure z. B. can be precisely controlled in a nip or roll nip, although the level of supply pressure fluctuates slightly or decreases. The set of digital valves is in addition to the hydraulic cylinder Also assigned to the accumulator to the pressure and the of the Control accumulator output volume flow. When the accumulator is exhausted, d. H. the energy stored in it The set of digital valves can switch to pump operation. The pressure control is carried out directly with the pumped working fluid and at the same time the accumulator is recharged. Then the pump switches off again and it becomes working fluid again taken from the pressure accumulator, which energy costs significantly can be lowered.

The Invention can be found in numerous modifications and options in the Practice are implemented, some of which are described below become. These modifications contribute to a simplified structure the hydraulic cylinder assembly and / or to reduce energy consumption at.

A common one digital hydraulic pressure regulator usually has a number or Bank of valves connected in parallel for feeding of working fluid to a pressure chamber of a hydraulic cylinder (eg. a single-acting plunger cylinder, a double-acting differential cylinder, etc.) and a bank of parallel valves for draining working fluid from this pressure chamber. As a rule, a differential cylinder associated with two pressure chambers a total of four valve banks. With a diverter valve (eg 4/2-way valve) can be a simplification of the construction can be achieved by each having a valve bank with each a cylinder pressure chamber is connected, while the switching valve the two valve banks alternately with the tank or the Pump (or the pressure source) connects.

Become digital hydraulic pressure regulator together with hydraulic cylinders used, so there is a particular advantage in that these controls have no leakage current. Therefore, there are working fluid volumes and piston position very closely related, d. H. do you measure that? The cylinder supplied working fluid volume, you can on Close the actual piston position. at the operation of such a cylinder, the piston position can be an important Size, especially when setting exact distances at great forces or regarding a synchronization of movements.

The conventionally used sensors for this task is located on the outside of the cylinder and thus the adverse environmental conditions of, for example, paper machines exposed where it is often dusty and / or humid. Thereby this sensor is prone to failure.

By the close relationship between the volume of working fluid dispensed by the regulator and the piston position can according to a development of Invention from a volume flow measurement in the working fluid stream, for example with gear flow meters, are closed to the piston position. In this case, the flow meter can be mounted in one place, which is removed from the piston rod (whose position is to be detected) is. In addition, you can encapsulate such flow meters, as they only to grasp something that happens inside. On This way is a reliable piston position detection possible. Even if a measurement error in the detection of Flow occurs, this sensor assembly, especially if Reciprocating flow to and from the cylinder separately detected and evaluated accurately enough to detect malfunctions.

It is also possible, from the operation of the digital hydraulic Regulator to close the postponed working fluid volume, by taking the individual streams through the individual valves of a controller taking into account the opening times summed up. In this way, possibly even any flow meter be saved. You can use the knowledge that the opening times the individual valves for the regulation calculated anyway and from the calculation with the individual flow rates through the appropriate valves on the in the respective pressure chamber present volume and thus closed to the piston position can be.

For rapid control of streams of working fluids, the principle of digital hydraulics can also be used for flow regulators. As a rule, large valves with large cross-sections are used to control the considerable volume flows of the working fluid whose control accuracy is limited. For example, in the headbox of a paper machine, it is necessary to precisely control the composition of the pulp suspension to produce a paper of consistent quality. In this case dilution of the suspension (dilution) should be controlled by addition of water. This addition of water to set a desired dilution can be controlled very precisely and responsively by means of digital hydraulic valve arrangements by opening or closing the valves at the appropriate flow rates, as described above. By using several such digital hydraulic flow regulators with corresponding cross sections (the valves must still be able to be switched quickly enough), it is also possible to control large-volume material flows.

One important criterion for quality (accuracy, overshoot, etc.) of the control by means of digital hydraulic controllers is the Switching speed of the individual valves, d. H. how fast the Valves can be opened or closed. For rapid movement of the valve body in the valve But larger (acceleration) forces are required as for holding the valve in the driven state. For this Basically, so-called for the adjustment process Boosters or amplifiers are used, which is a coil of the solenoid-operated valve for a short time supply a surge, making a stronger Magnetic field arises and the valve body moves faster can be. An advantage of this technique is that this Coils only need to be sized so big that they survive this short-term overload and endure a lower voltage in continuous operation.

The previously described digital hydraulic controller arrangements usually operated with hydraulic oil as working fluid. The use of oil is for the usual Control valves for lubrication of the control piston basically required or at least beneficial. After the digital hydraulic Regulator use only simple shut-off valves, there are these Lubrication requirement is no longer or not so much. Therefore, the working fluid may also be an aqueous emulsion (eg an oil / water emulsion similar to the Bohrmilch) or even simple water.

Next a significant reduction in the effort that will be made must protect the environment from pollution by leaking oil there are also technical advantages. The viscosity of oil is temperature dependent. In digital hydraulic Controllers are usually fixed chokes for adjusting the flow rates provided by the individual valves whose throttling effect a distinct dependence on the viscosity of the Working fluids shows. For water or aqueous emulsions the temperature has only a slight influence on the viscosity, so that the temperature sensitivity of the hydraulic system low is. Thus, it is not necessary, the temperature of the working fluid to be considered at the place of use of the digital hydraulic controller.

The The invention will be described below with regard to various aspects by way of exemplary embodiments, by reference below to the figures explained in which the following shown is:

1 shows a schematic structure of a portion of a hydraulic cylinder assembly with digital hydraulic pressure regulators;

2 shows a schematic structure of a portion of a hydraulic cylinder assembly with digital hydraulic pressure regulators, which are hydraulically connected to each other by differential pressure control valves;

3 shows a portion of a hydraulic cylinder assembly with digital hydraulic pressure regulators, a differential pressure control valve, a hydraulic differential cylinder, an integrated pump and a tank, and a pressure accumulator in a schematic diagram;

4 shows a portion of a hydraulic cylinder assembly with digital hydraulic pressure regulators, a differential pressure control valve, a hydraulic differential cylinder, an integrated pump, a tank and a pressure accumulator in a schematic diagram;

5 shows a schematic structure of a hydraulic cylinder assembly with digital hydraulic pressure regulators, the valves are arranged in a piston of the hydraulic cylinder;

6 shows a portion of a hydraulic cylinder assembly with digital hydraulic pressure regulators, a differential pressure control valve and a hydraulic differential cylinder, and a pressure accumulator in a schematic diagram; and

7 shows a portion of a hydraulic cylinder assembly with a digital hydraulic pressure regulator, a differential pressure control valve, a hydraulic differential cylinder and a directional control valve, and a pressure accumulator in a schematic diagram.

In the following description of the figures, the same or functionally identical elements are denoted by the same reference numerals, so that the general functional description merely hand made a Fig. and then referenced. Furthermore, if the text below refers to pressure regulators or flow regulators, these are, unless otherwise stated, digital hydraulic pressure regulators or flow regulators which operate using the digital hydraulic principle explained in the description at the outset.

In the 1 is a construction of a portion of a hydraulic cylinder assembly 1 according to a first embodiment of the present invention shown schematically.

This hydraulic cylinder assembly 1 has a hydraulic cylinder 2 and four digital hydraulic pressure regulators 3 on. The hydraulic cylinder 2 is a hydraulic differential cylinder 2 and has a cylinder housing 21 and a piston movable in the cylinder housing 27 , The cylinder housing 21 is through a head of the piston 27 in a cylinder head chamber 22 and a cylinder bottom chamber 23 divided. Furthermore, the cylinder housing 21 one to the cylinder head side chamber 22 corresponding antechamber 24 and one to the cylinder bottom side chamber 23 corresponding antechamber 25 on. These two atria 24 . 25 are separated from each other by a partition 26 that differ from the scope of the cylinder housing 21 radially outward and annular around the housing 21 extends around, hydraulically isolated. The two atria 24 . 25 are through a the cylinder housing 21 formed fluid-tight surrounding cylinder shell, whereby a to the cylinder head side chamber 22 corresponding annulus (ie, the cylinder head side prechamber 24 ) and to the cylinder bottom side chamber 23 corresponding annulus (ie, the cylinder bottom side antechamber 25 ) between the cylinder housing 21 and the cylinder cover 29 are fixed. These two annular spaces are through the between the cylinder housing 21 and the cylinder cover 29 arranged partition 26 hydraulically separated from each other. The partition 26 is with the cylinder housing 21 and the cylinder cover 29 firmly connected (eg welded).

A piston rod 28 of the piston 27 is in the cylinder head chamber 22 arranged. The piston 27 is in the usual way in the cylinder housing 21 slidably received to be in this reciprocable. The piston rod 28 occurs on the cylinder head side through a hole in the cylinder head cover 29 through which the cylinder housing 21 and thus both the cylinder head side chamber 22 as well as the cylinder bottom chamber 23 encloses fluid-tight and seals.

Two digital hydraulic pressure regulators each 3 are on a common supply line 32 or a common outlet line 33 connected or arranged integrated in this. Every pressure regulator 3 points in the supply line 32 or outlet line 33 five digital hydraulic valves arranged in parallel 31 (ON / OFF valves) and throttle elements 34 on, directly on the cylinder cover 29 of the hydraulic cylinder 2 are attached.

For example, as the valve 31 a common control valve of the type GSR-RRV 95 which z. In EP 1 052 441 A2 is described. The operation and structure of such a digital valve are described in detail in this document.

The common supply line 32 as well as the common outlet line 33 is filled with a working fluid (for example, hydraulic oil, air, etc.). By installing the throttle elements 34 to the digital hydraulic valves 31 in appropriate line 32 . 33 is ensured that the valves 31 have different flow rates when opened. For example, by the upstream throttle elements 34 the flow rates Q of the working fluid in the individual, each of the corresponding associated valves 31 optionally available passages in the ratio of 1: 2: 4: 8: 16 to each other.

The common supply line 32 is thus on the parallel valves 31 and throttle elements 34 the two pressure regulators 3 which is on the left in 1 are shown schematically, with the cylinder head side chamber 22 as well as with the cylinder bottom side chamber 23 hydraulically connected. The common outlet pipe 33 is also about the parallel valves 31 and throttle elements 34 the two pressure regulators 3 which is on the right in 1 are shown schematically, with the cylinder head side chamber 22 as well as the cylinder bottom chamber 23 hydraulically connected.

Sensors (not shown) detect the pressure and temperature in the two pressure chambers 22 and 34 of the differential cylinder 2 , The pressure in the cylinder bottom side (piston rod side) pressure chamber 23 acts on a rod-side piston ring surface 281 while the pressure in the cylinder head side (piston side) pressure chamber 22 on the piston surface 271 suppressed. The piston surface 271 includes an annular surface of the piston 27 and a frusto-conical surface of a brake cone of the piston 27 on the cylinder head side. Other sensors (not shown) detect the pressure Pzu in the supply line 32 and the pressure Pab in the exhaust line 33 , With the four pressure regulators 3 can fill level and pressure in the two pressure chambers 22 and 23 be adjusted so that the piston rod 28 in the desired position and with the desired force with a machine connected to it ment (not shown).

The pressure Pzu in the supply line 32 , starting from the cylinder 2 is to be controlled, is measured by means of the pressure sensor and from this, the target pressure in the pressure chambers 22 and 23 by appropriate regulation of the flows in the valves 31 the pressure regulator 3 adjusted to the piston rod 28 inside the cylinder housing 21 slidable to move and bring in a desired target position. D. h., By appropriate switching on and off of the valves 31 attached to the cylinder cover 29 are attached, thus, an inflow and outflow of the working fluid to and from the respective chambers of the hydraulic cylinder 2 thereby controlling the pressure of the working fluid in at least one of the cylinder head side chamber 22 and the cylinder bottom chamber 23 adjust, reducing the position of the piston 27 inside the cylinder housing 21 is adjusted accordingly.

In the 2 is a schematic structure of a portion of a hydraulic cylinder assembly 1 according to a second embodiment of the present invention shown schematically.

The structure of this embodiment substantially corresponds to the structure of the hydraulic cylinder assembly 1 , like in the 1 is shown. However, this hydraulic cylinder assembly includes 1 additionally two differential pressure control valves 35 of which one each has a direct hydraulic connection between the cylinder head side prechamber 24 and the cylinder bottom-side antechamber 25 on the supply line side and the discharge line side, respectively.

Each differential pressure control valve 35 is on the cylinder cover 29 in the area of the partition 26 , so in the area between the cylinder head side pre-chamber 24 and the cylinder bottom-side antechamber 25 on the cylinder cover 29 arranged, and thus within the assembly 1 integrated.

Through the respective differential pressure control valve 35 that the two chambers 22 . 23 of the cylinder 2 hydraulically connected to each other, the working fluid can flow at high pressure level from one pressure chamber to the other and it is thus only necessary to provide such a pumping energy required for further pressure increase in the respective chamber to the position of the piston rod 27 to change. That is, the differential pressure control valve 35 regulates a flow of working fluid between the cylinder head side chamber 22 and the cylinder bottom chamber 23 ,

The differential pressure control valve is preferred 35 during a rapid positional adjustment of the piston 27 and the piston rod 28 controlled (ie open) to allow a flow from one pressure chamber to the other, without requiring additional flow control of the cylinder envelope 29 attached valves 31 must be used to an increased extent. The function of this differential pressure control valve 35 that has a hydraulic connection between the two chambers 22 and 23 optional, is below with reference to 3 explained again.

3 shows a portion of a hydraulic cylinder assembly 1 according to a third embodiment with digital hydraulic pressure regulators 3 , a differential pressure control valve 35 , a hydraulic differential cylinder 2 , an integrated hydraulic pump 4 and a tank 6 , and a pressure accumulator 5 in a schematic diagram.

A supply section with the accumulator 5 , the hydraulic pump 4 and the tank 6 supplies the four pressure regulators 3 for operation of the differential cylinder 2 , Sensors detect the pressure in the two pressure chambers 22 and 23 of the differential cylinder 2 passing through the piston 27 with the piston rod 28 are separated. With the pressure regulators 3 can fill level and pressure in the two pressure chambers 22 and 23 be adjusted so that the piston rod 28 in the desired position and with the desired force with a machine element connected thereto (not shown) cooperates.

The pressure in the pressure supply section, starting from the cylinder 2 is to be controlled by means of a pressure sensor 41 measured and based on this, the target pressure in the pressure chambers 22 and 23 set.

In the 3 has in contrast to the structure of the hydraulic brush group 1 from 1 each of the four digital hydraulic pressure regulators 3 six instead of five digital valves 31 on. The to the digital hydraulic valves 31 associated throttle elements 34 have different throttle openings, ie the throttle diameters are in the ratio 0.3: 0.4: 0.6: 0.8: 1.1: 1.5 mm to each other.

Furthermore, the hydraulic pump 4 , which is drivable by an electric motor, as one in the assembly 1 integrated pump and tank (oil tank or working fluid tank) 6 within the assembly 1 attached (integrated), which is indicated by the dotted line in 3 is shown. The pump 4 serves to supply the working fluid with enough high pressure for the digital hydraulic pressure regulator 3 to provide or the pressure in a pressure accumulator 5 that is not in the assembly 1 is integrated. Because the pump with the accumulator 5 hydraulically connected, is an operation of the pump 5 only necessary to the pressure in the accumulator 5 back to a certain level of pressure. Thus, most of the time can be a pressure for the digital hydraulic pressure regulator 3 from the accumulator 5 be provided without the pump 4 is operated by the electric motor.

Thus, the pressure regulators 3 , the pump 4 with her electric motor drive and the tank 6 as a separate block on the cylinder housing 21 arranged, and the pressure regulators are via hydraulic lines 34 directly with the cylinder head side chamber 22 or the cylinder bottom side chamber 23 hydraulic connected. Prechambers are not provided in this embodiment.

By a correspondingly close arrangement of the pressure regulator 3 , the pump 4 and the tank 6 on the cylinder 2 No long hydraulic lines are required.

Further, between the two chambers 22 . 23 in the hydraulic circuit of the hydraulic cylinder assembly 1 a connecting line with the differential pressure control valve 35 connected, the pressure chambers in the closed state 22 . 23 separates each other. When the differential pressure control valve 35 opens, the two pressure chambers are connected or shorted together. As a rule, is due to the piston rod 28 a load or force that endeavors to be the piston rod 28 in the cylinder 2 push in. Shall now the piston rod 28 following the load into the cylinder 2 be retracted, as occurs for example when opening a nip, so the differential pressure control valve 35 opened and the digital valves 31 to the cylinder bottom side chamber 23 corresponding pressure regulator 3 stay closed. The working fluid thus flows partly into the cylinder head side chamber 22 and partly in the tank 6 , The drain into the tank is from to the cylinder head side chamber 22 corresponding pressure regulators 3 controlled and thus the lowering speed of the piston rod 27 controlled.

Because the working fluid is short-circuited to the cylinder bottom pressure chamber 23 to fill, this amount of working fluid does not have to be taken from the pressure supply section. So the working fluid does not have to be from the pump first 4 be promoted and brought to high pressure, then with down regulated pressure in the pressure chamber 23 to be fed. Overall, that's from the pump 4 reduced to moving volumes, which saves energy.

Because further to the cylinder bottom side chamber 23 corresponding pressure regulator 3 stay off, eliminating the billing and control effort. This halves the computational effort and the computing power for the controller 3 and also saves the drive energy for the operation of their valves 31 one.

Usually, as shown in this embodiment, the pump 4 driven by an electric motor. As in this embodiment, the pump 4 Most of the time is not needed to put pressure in the digital hydraulic pressure regulator 3 This can often be left off, thereby reducing the energy consumption required to operate the pump 4 (an operation of the electric motor) can be lowered considerably. By this arrangement, an energy saving of more than 99% compared to control valves is possible, which adjust a hydraulic actuator with a sliding spool or spool analog hydraulically.

According to this example, therefore, the hydraulic cylinder assembly 1 to control a nip of a paper machine calender. The gap is closed when the piston 27 of the cylinder 2 in the direction of the cylinder head side chamber 22 is urged. When the piston 3 at its lowest position in the cylinder bottom chamber 23 is arranged, the nip is fully open and in the highest position in the cylinder head side chamber 22 the nip is completely closed. To open the nip no energization is required because by appropriate control of the digital and differential pressure control valves 35 a portion of the oil in the cylinder bottom chamber 23 to the cylinder head side chamber 22 of the hydraulic cylinder 2 via the differential pressure control valves 35 is guided or a part back to the tank 4 to be led.

At this pressure control in the chambers 22 . 23 the hydraulic cylinder assembly 1 a small amount of oil is required, whereby it is possible that an oil flow is required only during the closing movement of the nip, ie, it is necessary only during the closing of the nip that of the pressure accumulator 5 or by operation of the pump 4 Oil in the oil circuit of the hydraulic cylinder assembly 1 is fed.

4 shows substantially the same structure as the embodiment in 2 the hydraulic cylinder assembly 1 in which the digital hydraulic pressure regulator 3 and the differential pressure control valves 35 directly on the cylinder cover 29 are attached. Furthermore, in this embodiment, the hydraulic cylinder assembly includes 1 also the pump 4 , the tank 6 as well as the accumulator 5 , Ie. the pump 4 , The Tank 6 and the accumulator 5 are in the assembly 1 integrated, which by the outer dotted lines schematic Darge is is. Thus, in this embodiment, the hydraulic lines between the individual components of the assembly 1 be further shortened.

In 5 is another embodiment of the invention hydraulic cylinder assembly 1 with digital hydraulic pressure regulators 3 shown schematically, their valves 31 . 35 and throttle elements 34 in the piston 27 of the hydraulic cylinder 2 are arranged. The operation of this hydraulic cylinder assembly 1 is the same as those described above in the embodiments of 1 to 4 is described.

In contrast to the structural design of the hydraulic cylinder assembly 1 the above-described embodiments of 1 to 4 is the piston in this hydraulic cylinder assembly 27 a reciprocating double-acting, hollow piston provided with a hollow piston rod. In the head of this hollow piston 27 are the valves 31 and throttle elements 34 , which are described in detail above, arranged. The hydraulic and electrical wiring of the digital hydraulic pressure regulator 3 are through the hollow piston rod 28 through to the respective parallel valves 31 of the digital hydraulic pressure regulator 3 guided. In this embodiment, the volumes of the cylinder head side chamber 22 and the cylinder bottom chamber 23 essentially the same size.

In this design of the piston 27 It is also ensured that the valves 31 the hydraulic pressure regulator 3 are installed in the piston such that their outlets A, B directly to the cylinder head side chamber 22 and the cylinder bottom chamber 23 of the hydraulic cylinder 2 are assigned, so that the piston rod 28 ultimately occupying a position that is essentially offset by the pressure regulator 3 adjusted difference in the pressures in the cylinder head side chamber 22 and the cylinder bottom chamber 23 of the hydraulic cylinder 2 depends.

Furthermore, as already in the embodiment of 4 is shown, the accumulator 5 as well as the pump 4 , which is driven by an electric motor, and the oil tank 6 with the respective parallel valves 31 and throttle elements 34 hydraulically connected. For the valves 31 For example, a hydraulic digital valve may be provided here (eg, a 750 series matrix valve).

In this structure, the hydraulic cylinder assembly 1 can by the arrangement of the pressure regulator 3 in the piston 27 also on the cylinder shell and thus on the antechamber in the design of the cylinder housing 21 be waived.

This type of hydraulic cylinder assembly 1 according to the embodiment of 5 is used for example in adjusting cylinders in Mehrwalzenkalandern.

Further embodiments according to the present invention are in the 6 and 7 shown. 6 shows a portion of a hydraulic cylinder assembly with digital hydraulic pressure regulators, a differential pressure control valve and a hydraulic differential cylinder, and a pressure accumulator in a schematic diagram. 7 shows a portion of a hydraulic cylinder assembly with digital hydraulic pressure regulators, a differential pressure control valve, a hydraulic differential cylinder and a directional control valve, and a pressure accumulator in a schematic diagram.

In these two embodiments according to 6 and 7 is also the differential pressure control valve 35 between the cylinder head side chamber 22 and the cylinder bottom chamber 23 arranged to provide a hydraulic connection between these two chambers, in particular during the piston 27 to perform a quick movement.

As shown by 6 consists of the hydraulic cylinder assembly 1 (see dot-dash line) from two digital hydraulic pressure regulators 3 , the differential pressure control valve 35 , two to the digital hydraulic pressure regulators 3 associated digital valves 36 and the hydraulic differential cylinder 2 , The accumulator 5 is with the assembly 1 hydraulically connected.

With the two pressure regulators 3 in 6 become the pressures and filling volumes of the pressure chambers 22 . 23 of the differential cylinder 2 regulated; this was previously explained in detail with another controller design, so that a repetition is omitted here.

The two pressure regulators 3 each have five digital valves 31 which are connected in parallel within the respective regulator; the controllers 3 may have the same structure as in the previously explained in detail pressure regulators of the previous embodiments.

The pressure regulator 3 have a structure like that with reference to 2 . 3 and 4 described pressure regulator 3 , The in the figure above arranged pressure regulator 3 is connected to a tank (not shown) while the lower pressure regulator 3 with the accumulator 5 connected is. The thus pressurized lower regulator 3 can be working fluid in the connected pressure chamber 22 of the cylinder 3 deliver while working fluid from the other pressure chamber 21 over the upper regulator 3 can drain into the tank.

If z. B. the differential pressure control valve 35 is closed, the pressure of the cylinder bottom chamber 23 be adjusted to generate larger forces. Thus, then in the cylinder head side chamber 22 acting pressure to the tank via a dispensing valve delivered (not shown). By the hydraulic coupling of the two chambers by means of the differential pressure control valve 35 will if the piston 27 in the direction of the cylinder bottom side chamber 23 is forced, the working fluid through the differential pressure control valve 35 directly to the cylinder head side chamber 22 supplied, whereby a volume flow of the working fluid through the digital valves 31 and the throttle element 34 in the pressure regulators 3 to the tank (not shown) is extremely low.

As in 7 can be shown by the additional use of a directional control valve 37 (ie 4/2-way valve) upstream of the group of digital valves 31 the number of digital hydraulic pressure regulators 3 can be reduced to one, which also increases the total number of digital valves 31 . 35 . 36 reduced to nine. The directional control valve 37 can control the flow of oil such that the chambers alternately 22 . 23 can be pressurized.

In both embodiments of the hydraulic cylinder assembly in 6 and 7 takes during the movement of the piston 27 the volume of the one pressure chamber while the volume of the other pressure chamber increases; There are no operating conditions in which both pressure chambers are pressurized simultaneously or both are discharged simultaneously.

With this arrangement of pressure regulators, the required number of digital valves compared to the arrangement of pressure regulators in the embodiments of 1 to 5 halved ( 6 ) or even further reduced ( 7 ) become. Thus, the investment costs for the machine for producing a fibrous web, in particular a paper or board machine, can be further reduced.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - EP 1052441 A2 [0005, 0052]

Claims (14)

Hydraulic cylinder assembly ( 1 ) for a machine for producing a fibrous web, in particular a paper or board machine, with a hydraulic cylinder ( 2 ), which is a cylinder housing ( 21 ) and one in the cylinder housing ( 21 ) movable piston ( 27 ) comprising the cylinder housing ( 21 ) in a cylinder head side chamber ( 22 ) and a cylinder bottom side chamber ( 23 ) and at least one digital hydraulic pressure regulator ( 3 ), which is in the assembly ( 1 ), which is the cylinder head side chamber ( 22 ) and the cylinder bottom side chamber ( 23 ) and the inflow and outflow of working fluid to and from the chambers ( 22 . 23 ) to control the pressure of the working fluid in at least one of the two chambers ( 22 . 23 ) of the hydraulic cylinder ( 2 ). Hydraulic cylinder assembly ( 1 ) according to claim 1, characterized in that valves ( 31 ) of the digital hydraulic pressure regulator ( 3 ) directly on the hydraulic cylinder ( 2 ) are mounted. Hydraulic cylinder assembly ( 1 ) according to claim 1, characterized in that valves ( 31 ) of the digital hydraulic pressure regulator ( 3 ) in the piston ( 27 ) of the hydraulic cylinder ( 2 ) are mounted. Hydraulic cylinder assembly ( 1 ) according to one of claims 1 to 3, characterized in that the piston ( 27 ) a reciprocating piston ( 27 ) with piston rod ( 28 ). Hydraulic cylinder assembly ( 1 ) according to claim 2, characterized in that the cylinder housing ( 21 ) one to the cylinder head side chamber ( 22 ) corresponding antechamber ( 24 ) and to the cylinder bottom side chamber ( 23 ) corresponding antechamber ( 25 ) which are hydraulically separated from each other and to which the valves ( 31 ) of the digital hydraulic pressure regulator ( 3 ) are directly attached. Hydraulic cylinder assembly ( 1 ) according to claim 5, characterized in that the two antechambers ( 24 . 25 ) through a cylinder housing ( 21 ) fluid-tight surrounding cylindrical shell ( 29 ) and one to the cylinder head side chamber ( 22 ) corresponding annulus ( 24 ) and to the cylinder bottom side chamber ( 23 ) corresponding annulus ( 25 ), wherein the annular spaces ( 24 . 25 ) by a between the cylinder housing ( 21 ) and the cylinder envelope ( 29 ) arranged partition ( 26 ) are hydraulically separated from each other and at the peripheral surfaces of the valves ( 31 ) of the digital hydraulic pressure regulator ( 3 ) are mounted. Hydraulic cylinder assembly ( 1 ) according to claim 6, characterized in that the cylinder envelope ( 29 ) and the partition ( 26 ) in one piece on the cylinder housing ( 21 ) are formed. Hydraulic cylinder assembly ( 1 ) according to one of claims 1 to 7, characterized in that the digital hydraulic pressure regulator ( 3 ) a differential pressure control valve ( 35 ), which provides a direct hydraulic connection between the cylinder head chamber ( 22 ) and the cylinder bottom side chamber ( 23 ) and a flow of working fluid between the cylinder head side chamber ( 22 ) and the cylinder bottom side ( 23 ) Chamber controls. Hydraulic cylinder assembly ( 1 ) according to claim 3, characterized in that the piston ( 27 ) is a reciprocating hollow piston with a hollow piston rod. Hydraulic cylinder assembly ( 1 ) according to claim 9, characterized in that in the hollow piston the valves ( 31 ) of the digital hydraulic pressure regulator ( 3 ) are arranged and the hydraulic and electrical wiring of the digital hydraulic pressure regulator ( 3 ) through the piston rod to the valves ( 31 ) is guided. Hydraulic cylinder assembly ( 1 ) according to one of claims 1 to 10, characterized in that the volumes of the cylinder head side chamber ( 22 ) and the cylinder bottom side chamber ( 23 ) are the same size. Hydraulic cylinder assembly ( 1 ) according to one of claims 1 to 11, characterized in that the assembly ( 1 ), an integrated pump ( 4 ) to supply the working fluid at a sufficiently high pressure to the digital hydraulic pressure regulator ( 3 ). Hydraulic cylinder assembly ( 1 ) according to claim 12, characterized in that the pump ( 4 ) directly on the hydraulic cylinder ( 2 ) is attached. Hydraulic cylinder assembly ( 1 ) according to claim 12 or 13, characterized in that the pump ( 4 ), the working fluid at high pressure in one with the digital hydraulic pressure regulator ( 3 ) hydraulically connectable pressure accumulator ( 5 ) and pressurizes it.