WO2011009879A1 - Method for controlling delivery quantity, and reciprocating compressor having delivery quantity control - Google Patents

Abstract

The invention relates to a method for the delivery quantity control of a reciprocating compressor, wherein the motion of a closing organ (5b) of an automatic suction valve (5) is influenced during at least one part of a cycle of the crankshaft by means of a retraction gripper (6) driven by a control device (2), wherein the method comprises a continuously variable return flow control, wherein the retraction gripper (6) contacts the closing organ (5b) and prevents the same from closing during a first partial segment (K1) of the cycle of the crankshaft, and wherein the retraction gripper (6) is retracted during a second partial segment (K2) of the cycle of the crankshaft and the closing organ (5b) is closed, and wherein the method comprises an interruption control, wherein the retraction gripper (6) prevents the closing organ (5b) from closing during an entire cycle of the crankshaft, wherein the delivery quantity is controlled at least by a combination of continuously variable return flow control and interruption control, and wherein the closing organ (5b) is influenced by the control device (2) and the retraction gripper (6) such that a closing organ (8b) of a pressure valve (8) of the reciprocating compressor is opened at least during a prescribed total opening angle (Kv) of a crankshaft.

Description

 PROCEDURES ON THE SUPPLY VOLUME REGULATION AND

PISTON COMPRESSOR WITH

FLOW CONTROL

description

The invention relates to a method for flow control of a reciprocating compressor according to the preamble of claim 1. The invention further relates to a reciprocating compressor with

Flow control according to the preamble of claim 16.

State of the art

Documents EP 0801227 A2 and EP 1400692 A1 disclose

Method for influencing the pressure-dependent automatic, periodic opening movement of a closing member of a suction valve of a reciprocating compressor by means of a, if necessary, at least over a part of the crank circuit acting on the closing member control means. Since the life of mostly suction and pressure side used, automatic compressor valves is primarily influenced by the impact stress at the alternate impact of the actual closing organ on seat or catcher, said document discloses a method in which the

Suction valve by means of a so-called Abhebegreifers before reaching the Pressure equilibrium is forcibly opened, in order to avoid a strong instantaneous acceleration of the closing member towards the catcher, which would occur during automatic opening. This allows the impact load of the

Reduce compressor valve.

 This method has the disadvantage that the suction and

In particular, the compressor valves used on the pressure side still have a high load, especially when the compressor system according to the method of a continuously variable

Backflow control is operated. In the stepless

 Backflow control, the suction valve is kept open by means of Abhebegreifers during a partial angle range of the compression stroke and then closed, thereby affecting the flow rate.

A disadvantage of this known method is the fact that the closing member of the suction valve and the pressure valve is subject to a relatively large wear, which is a correspondingly high

Maintenance required. Presentation of the invention

The object of the invention is a more advantageous method for

To make flow control of a reciprocating compressor. This object is achieved by a method comprising the features of claim 1. The dependent claims 2 to 15 relate to further advantageous method steps. The object is further achieved with a reciprocating compressor having the features of claim 16. The dependent claims 17 to 23 relate to further advantageous embodiments. The object is achieved in particular with a method for

Flow control of a reciprocating compressor by the movement of a closing member of a self-acting suction valve is influenced by means of a driven by a control Abhebegreifers during at least part of a cycle of the crank circuit

wherein the method comprises a continuous backflow control, in which the lift-off gripper rests against the closing member during a first part of the cycle of the crank circuit and the latter

Closure prevents, and in which the lifting gripper is moved back during a second portion of the cycle of the crank circle and the closing member is closed,

and wherein the method comprises a skip control in which the skimmer prevents the closing of the closing member during a whole cycle of the crank circuit,

wherein the flow rate is controlled at least by a combination of continuous backflow control and Aussetzregelung, and wherein the closing member by the control device and the

Lifting gripper is influenced such that a closing member of a pressure valve of the reciprocating compressor is opened at least during a predetermined total opening angle of a crank circle.

In the inventive method, the flow rate is controlled by the forced keeping open the suction valve. In this case, two different methods are used for control, namely a suspension control and the continuous backflow control. Both

Methods use a so-called Abhebegreifer which the closing member of the valve, for example, a plate, ring or

Poppet valve, push in an open position, and preferably press on the valve seat. The reciprocating compressor has a compression chamber, which is supplied via a suction valve gas, and from which via an outlet valve, also referred to as a pressure valve, compressed gas is discharged. In the process of Aussetzregelung the closing member of the suction valve is kept open during an entire working cycle or a whole working cycle. This increases the pressure during the compression phase

Compression space not on the pressure which is required to open the pressure valve, so that the sucked gas is pressed back into the suction line during the compression phase, and thus the compression and further transport into the pressure line is not available. The pressure valve thus remains closed and thus this compression chamber does not convey gas over the

Pressure valve in the pressure line. If the intermittent control is deactivated, that is, a normal operation is driven, the compression chamber again promotes the entire gas flow via the pressure valve in the

Pressure line. If, for example, the reciprocating compressor has only one compression chamber, then the intermittent control can be operated in such a way that certain working cycles are run with normal operation, and during certain working cycles the intermittent control can be operated

Intermittent control is activated. A disadvantage of the Aussetzregelung is thus that the amount of gas pumped by the reciprocating compressor can be regulated only gradually. Another disadvantage of

Aussetzregelung is that the unloaded compression chamber, that is, when not opening pressure valve, is not flowed through and can accumulate dirt in the compression chamber, which increases the wear of the valves or the packing rings and piston rings. In the process of backflow control, the suction valve with the help of Abhebegreifers during a partial angle range of

full compression stroke or a complete crank circuit kept open and then closed, thereby affecting the flow rate. The suction valve is pressed only at the beginning of the compression phase by the Abhebegreifer. As a result, a part of the gas located in the compression chamber is pushed back into the suction line. As soon as the closing member of the suction valve closes completely, the remaining gas in the compression chamber is compressed and pressed via the pressure valve in the pressure line.

During the backflow control, only a portion of the maximum possible gas flow from the compression chamber is thus conveyed via the pressure valve in the pressure line. A disadvantage of the method of backflow control is the fact that the opening time of the automatic pressure valve at smaller

Flow rates is reduced accordingly, and that at

Flow rates less than 40% of the nominal flow rate

Opening time of the pressure valve is shortened so that the

Opening and closing speeds of the pressure valve

can multiply. This leads on the one hand to an increased

Wear of the automatic pressure valve, and on the other hand, this reduces the range within which partial flow rates can be reliably promoted. Another disadvantage of the backflow control is that the gas is heated more strongly before compression due to the longer residence time in the compression chamber and due to the heat transfer through the cylinder wall and due to a

Leakage current across the piston. This has the consequence that the gas has an elevated temperature on the pressure side. - -

The erfϊndungsgemässe method has the advantage that by the combined use of backflow control and intermittent control, the volume delivered by the reciprocating compressor can be varied within a wide range, in particular without additional

Wear of the closing organ of the suction valve and / or the

 Pressure valve. The reduction of the wear of the pressure valve is in particular the fact that the suction valve is kept open at low flow rates during certain cycles according to the Aussetzregelung and thus no gas is compressed, and that at

a sufficient amount of gas is compressed after the compression process, so that the closing member of the pressure valve remains open for a predetermined total opening angle,

or so that the closing member of the pressure valve does not fall below a minimum opening angle. For the control of the flow rate are essentially preferably three

different methods available, which can be applied. In addition to a method with maximum delivery, in which the suction valve closes automatically, nor the already described method of backflow control and the already described

Method of suspension control. Depending on the amount of fluid to be delivered in each case, the control can take place, for example, as follows:

 - To promote the maximum flow, the suction valve is not affected and thus opens and closes automatically.

- For large flow rates, ie flow rates in the range between about 100% and 80% of the maximum flow rate, a continuous backflow control is used. Whereby it is also possible that not every cycle of the crank circuit is regulated with the backflow control, but the suction valve is also operated, for example, one or two cycles automatically and thus without interference. This method has the advantage that the lift-off gripper is subjected to less stress, resulting in longer service lives, and that the volume control itself consumes less energy.

 - At medium flow rates, ie at flow rates in the

 Range between about 80% and 50% of the maximum

 Flow rate, is the stepless with each cycle

 Backflow control used.

 - For small flow rates, ie at flow rates in the

 Range between about 50% and 0% of the maximum flow, the closing of the suction valve means of

 Dropout control during a certain number of cycles, such as one or two cycles, kept open. In the other cycles, either the suction valve can be operated automatically, or in addition, if necessary, the

 Backflow control can be used.

 Particularly advantageously, the suction valve is influenced by the control device and the Abhebegreifer such that the closing member of the pressure valve of the reciprocating compressor at least during a predetermined opening angle range or a

predetermined total opening angle of a crank circle is opened. The opening angle range is at least 10 ° and

preferably at least 20 ° to 30 °.

In a particularly advantageous embodiment of the inventive method of Abhebegreifer via a drive device, preferably an electromagnet, can be controlled very precisely, such that the speed of the closing closing member can be reduced prior to placement on the suction valve, so that the closing member at low speed on the suction valve hits and comes to rest, so that the closing organ thus "gentle" on the - o -

Suction valve touches down. In a particularly preferred method, the speed of the closing member during placement on the suction valve is less than 0, 1 m / s. This advantageous method reduces the wear of the closing organ in addition.

In a further advantageous embodiment, the

Drive device a controllable damping device in order to influence the speed of the lift-off gripper and in particular also the location of the reduced speed such that the

Closing member when closing at low speed on

Suction valve impinges, so that the closing member thus "gently" touches down on the suction valve and closes the damping device is particularly advantageous electrically controlled, and particularly advantageously comprises an electrorheological or magnetorheological

Liquid whose viscosity is electrostatically or electromagnetically changeable, so that the damping via electrical signals can be changed very quickly. However, the damping device can also be based on another principle and, for example, as

Be configured electromagnet.

The invention will be described in detail below with the aid of exemplary embodiments.

Brief description of the drawings

The used to explain the embodiments

1 shows a longitudinal section through a controllable valve; 2 shows an example of the movement of the lift-off gripper, the closing member of the suction valve and the speed of the lift-off gripper as a function of the crank angle;

3 shows the course of the pressure in the compression space of

 Reciprocating compressor with different operating methods;

4 shows the course of the valve lift of the suction valve and of the pressure valve in the operating method shown in FIG. 3;

Fig. 5 shows a load curve in a PV diagram at different

 Operating procedures; Fig. 6 characteristic sizes of the valve in function of

 Crank angle;

Fig. 7 shows schematically a reciprocating compressor.

8 shows schematically a control device for actuating the gripper acting on the suction valve;

Basically, the same parts in the drawings with the same

 Provided with reference numerals.

Ways to carry out the invention

Fig. 1 shows a longitudinal section through a controllable valve 1 comprising a compressor housing 4 with a suction valve 5 disposed therein, the position of which is influenced by a Abhebegreifer 6, wherein the Abhebegreifer 6 configured as a connecting rod connection means 7 from outside the

Compressor housing 4 arranged control device 2 is actuated. The compressor housing 4 comprises a lantern 4a, a gas space 4b, a compression space 4c and a lid 4d, wherein the

Compressor housing 4 also includes a not shown or not visible pressure valve 8, via which the compressed fluid can escape from the compression chamber 4c. The automatic intake valve 5 comprises a valve seat 5a, a closing member 5b movably mounted in a stroke direction B, also referred to below as a valve plate 5b, a valve catcher 5c and a return spring 5d. The lift-off gripper 6 comprises a plurality of gripper extensions 6a or fingers 6a, a guide 6b and a compression spring 6c. Of the

Lifting gripper 6 is, driven by the electromagnet 2 a, in

Lifting direction B slidably mounted, the tip of the

Gripper extensions 6a depending on the stroke in the direction B can abut the valve plate 5b, and in particular the valve plate 5b can press against the valve catch 5c, so that the valve plate 5b is no longer movable, and the valve 5 thereby remains forcibly opened. The control device 2 comprises a drive device as a

Electromagnet 2a with a magnet armature 2b, a magnetic core 2c and a magnetic coil 2d. The control device 2 further comprises a housing 2m, which via the connecting part 2e with the

 Compressor housing 4 is connected. The control device 2 also comprises a drive device 2i or a control device 2i, electrical lines 2k, 21, wherein the electrical line 21 the

Drive device 2i connects to the solenoid 2a. The control device 2 comprises two guides 2f, 2g around the

Electromagnet 2a and the connecting rod 7 slidably store in the stroke direction B. In addition, a filter 3 may be provided. In an advantageous embodiment, the control device 2 also includes a sensor such as a displacement sensor 2h, which the hub or the position of the electromagnet 2a or the position of the lift-off gripper 6 in the stroke direction B detected.

The controllable valve 1 shown in Figure 1 can now be controlled in different ways over the cycles of the crank circuit. A cycle is understood to mean a rotation of the crankshaft of the reciprocating compressor through 360 °.

Figure 2 shows the method of a continuous backflow control, wherein in Figure 2, the lifting movement A of the Abhebegreifers 6, the stroke B of the valve plate 5b and the speed C of the Abhebegreifers 6 are shown in function of the crank angle, wherein a single

Rotation of the crankshaft is shown, that is, Figure 2 shows the course over an angle between 0 ° and 360 °. From the

Lifting movement B of the valve plate 5b can be seen that the

Valve plate 5b during suction, in the illustrated

Embodiment in the angular range between about 90 ° and 1 10 ° automatically opens, so that the valve plate 5b rests against the valve catch 5c. In the method of continuously variable backflow control, after opening the valve plate 5b, as shown by way of example by the curve A, the lifting gripper 6 is moved or moved until it bears against the valve plate 5b. In addition, in Figure 2 with the curve C nor the speed of the Abhebegreifers 6 is shown. During automatic operation of the suction valve 5, the suction valve 5 would automatically close when reversing the direction of movement of the piston, in the example shown at 225 °. The process of stepless

Backflow control now causes the lift-off gripper 6 during a first part Kl of the cycle of the crank circuit on

Closing member 5b is applied and prevents its closure, and that the lifting gripper 6 during a second portion K2 of the Cycle of the crank circuit is returned according to the course of the curve A2, wherein the closing member 5b, namely the

Valve plate 5b, due to the applied pressure conditions of the movement of the Abhebegreifers 6 follows or rests on the Abhebegreifer 6, so that the valve plate 5b at some point, in the illustrated

 Example, at about 290 °, rests on the valve seat 5a and the valve 5 closes. In the further section K3 the lift-off gripper 6 is moved even further, so that this e.g. is spaced from the valve plate 5b. The movement of the closing member 5b is influenced via the drive device, in the illustrated embodiment via the solenoid 2a and the connecting rod 7 in the section K2 such that the lift-off gripper 6 as a function of the crank circle the stroke course A shown in Figure 2 or the speed course C shown in Figure 2 , wherein the electromagnet 2a is advantageously controlled such that the speed of the moving closing organ 5a before placing on the

Suction valve 5 is reduced, as shown in Figure 2. In an advantageous embodiment of the Abhebegreifer 6 is then moved in a further section K3 still in an end position,

advantageously as shown in the curve C with the "second hump" by again accelerated and then again

is braked so that the lifting gripper 6, as shown in the stroke course A in the section K3, spaced, that is, without direct contact with the closing member 5a, comes to a standstill. Of the

Electromagnet 2a is controlled in an advantageous method step such that the closing member 5b has a speed of less than 0, 1 m / s during placement on the suction valve. ~. o ~

The valve 1 can also be operated with the method of Aussetzregelung. In the Aussetzregelung the lifting gripper 6 is moved such that this during a whole cycle of

Cranking prevents the closing of the closing member 5b, preferably in that the Abhebegreifer 6 rests during the entire cycle on the closing member 5b, so that it remains open throughout the cycle.

Figure 7 shows schematically a reciprocating compressor comprising a compressor housing 4 with a movably mounted, via a

Piston rod 4f driven piston 4e, the partial one

 Compaction space 4c limited. On the compressor housing 4, a suction valve 5 is also arranged, via which the fluid or gas to be conveyed is sucked. The reciprocating compressor also includes a gripper 6, the one of a control device 2 comprising a

Drive device is driven. The control device 2, the suction valve 5 and the gripper 6 form a controllable valve 1. On the compressor housing 4, a pressure valve 8 is also arranged, via which the compressed gas leaves the compression chamber 4c. Of course, the reciprocating compressor can also a plurality of

Compression chambers 4c include, wherein each compression chamber 4c comprises a separate piston 4e with piston rod 4f, and wherein each compression chamber 4c comprises a separate, controllable valve 1.

FIG. 3 now shows the course of the pressure in a compression chamber 4c of a reciprocating compressor as a function of the crank angle for different operating methods. In the illustrated

Embodiment is the bottom dead center UTP at 90 °, that is, in this position, the compression chamber 4c reaches the maximum Volume. The top dead center OTP in this example is 270 °, ie in this position, the compression chamber 4c reaches the minimum volume. In the first section D, the movement of the closing member 5b of the suction valve 5 is carried out automatically, so that over a crank angle of 360 ° the pressure curve shown results. The

Movement of the closing member of the pressure valve 8 always takes place automatically in FIG. In the illustrated embodiment, the pressure-side pressure, for example, about 3.1 bar, wherein the pressure valve 8 opens in the illustrated embodiment, including bias by the valve springs at a pressure of about 3.2 bar. The pressure valve 8 opens approximately at a crank angle of 190 °. The automatic pressure valve 8 is fully opened in the illustrated embodiment during an angular range Kw of about 50 °, because the pressure valve 8 in this Maximaloffenwinkelbereich Kw has the maximum valve lift before the pressure valve 8 closes again. The total opening angle Kv, during which the valve is open, that is, the closing member is lifted from the valve seat, or the entire opening time of the pressure valve 8 is about 80 °. In the second section E a skip control is shown, in which, as described above, the closing member 5b is kept open over the entire crank angle of 360 ° from Abhebegreifer 6, so that in the compression chamber 4c of the illustrated

Pressure curve results. The pressure in the compression chamber 4c is constantly below 3.2 bar, so that the pressure valve 8 does not open automatically. In the third section F, a continuous backflow control is shown, in which, as described in Figure 2, the closing member 5b is kept open during part of the crank angle of 360 ° from Abhebegreifer 6, so that the pressure build-up in the compression chamber 4c based on the crank angle later, and the pressure curve shown results. The pressure valve 8 opens approximately at a ~ - -

Crank angle of 210 °. The automatic pressure valve 8 remains in the illustrated embodiment during a

 Maximum open angle range Kw of about 30 ° fully open before the valve lift, as shown in Figure 4 is reduced, and the valve 8 closes completely again after the total opening angle Kv. The total opening angle Kv, during which the valve 8 is open, or the total opening time of the valve is about 60 °.

In the suspension control is thus during a whole

Working times the suction valve 5 is kept open. As a result, the sucked gas is pushed back into the suction line during the compression phase and thus is the compression and further transport into the pressure line is not available. The compression chamber does not deliver gas. If the skip control deactivates the

Compression space again the full fluid flow.

In contrast, in the continuously variable backflow control, the closing element 5b of the suction valve 5 is pressed on only at the beginning of the compression phase. As a result, a portion of the gas is forced back into the suction line. Closes the suction valve 5, the remaining gas can be compressed in the compression chamber and pressed by the pressure valve in the pressure line. The compression chamber promotes only part of the maximum possible gas flow.

Both methods use the lift-off gripper 6 to push the sealing element 5b of the valve 5, for example a plate, ring or poppet valve, against the valve catcher 5c and thus into the open position. Since in the continuous backflow control of the lift gripper 6 in a work cycle of the - -

closed in the open position and must be moved back again, and there in the suspension control for the same sequence of movements a longer time available

stands are the power consumption, the required forces, the

Traversing speeds and the stress of the components used in the stepless backflow control higher.

The flow rate of a reciprocating compressor can now, as indicated in Figure 3, by a combination of stepless

Backflow control F and Aussetzregelung E are regulated in a wide range, which also still the section D to

Flow control can be used, during which the closing member 5b moves automatically. These three types of operation D, E, F of operating the valve 5 can now be combined with each other, so that, for example, during successive cycles initially only the type of operation D, E or F takes place, and later, for example, a combination of at least two of the three types of operation D, E and F.

The valve could for example be controlled such that different flow rates are controlled so that the

 Suction valve 5 is operated automatically at high flow rates during certain cycles, and is operated during certain cycles according to the continuous backflow control,

that the suction valve 5 at medium flow rates during each

Cycle is operated according to the continuous backflow control, and that the suction valve 5 is kept open at low flow rates during certain cycles, and operated during certain cycles according to the continuous backflow control. FIG. 4 shows the lifting movement 8c of the pressure valve 8 as a function of the crankshaft angle. In addition, the lifting movement is 5e of

Closing member 5b of the suction valve 5 in function of

Crankshaft angle shown. The movement of the pressure valve 8 takes place automatically, whereas the movement of the closing member 5 b of the

Suction valve 5 as described above in the Aussetzregelung E and the backflow control F is determined by the gripper 6. Well

can be seen in Figure 4, the maximum open angle range Kw, within which the valve 8 has a maximum valve lift, that is, the maximum is open. In addition, the total opening angle Kv

seen during which the valve 8 is opened.

The opening duration of the automatic pressure valve 8 is determined by the angular range during which the pressure in

Compaction space 4c is above the opening pressure of the pressure valve 8, in the embodiment according to Figure 3 above a pressure of 3.2 bar. From the continuously variable in Fig. 3 and 4 shown with F.

Backflow control can be seen that the angular range of the open pressure valve 8 is reduced, the later the closing member 5b is closed. This has the consequence, in particular at low flow rates, that the pressure valve 8 only during a very short

Total opening angle Kv would be open if constantly the

Backflow control would be used. In order to increase the total opening angle Kv of the pressure valve 8 at low flow rates, the reciprocating compressor is operated such that the Aussetzregelung E is used during one or more Kurbeizyklen to promote in the subsequent backflow control F a large enough amount of gas, so that the pressure valve 8 over one

Total opening angle Kv of at least 10 ° and preferably over a total opening angle Kv of at least between 20 ° and 30 ° - o -

remains open. This has the consequence that the pressure valve 8 is opened long enough to excessive blows or excessive

To avoid opening or closing speeds. This considerably extends the life of the pressure valve 8. FIG. 5 shows a load curve in a PV diagram in the case of different operating methods, namely, as already shown in FIG. 3, at full load D with automatic intake valve 5, at intermittent control E and at stepless return flow control F.

A compressor may be configured such that, as shown in FIG. 7, it has only one compression space 4c per cylinder, such a compression space 4c also being referred to below as an upper compression space. The compressor may also be designed such that it has a second compression chamber in the same cylinder, which is separated from the first compression chamber by the piston 4e, so that during the movement of the

Piston 4e the fluid is compressed in a compression space and sucked in the other compression space. The second

Compaction space is below as lower

Referred to compaction space. In a particularly advantageous

Procedure, the flow rate control as indicated in Figure 3 such that the pressure valve 8 of the reciprocating compressor at least during a predetermined angular range Δ of 20 ° to 30 ° before reaching the top dead center OTP (upper compression space) respectively bottom dead center UTP (at the lower compression space if the cylinder includes two compression spaces) of the crank circuit opens. The advantage of this method is that only the

Opening time must be determined because the closing time is reasonably well known and an idealized valve in Dead center of upper or lower if available

Verdichtungsraumes lies.

The opening time of the pressure valve 8 can be determined for example via a measurement of the pressure in the compression chamber and comparison with the final pressure, or with knowledge of the operating cases of the compressor over a previous, respectively simultaneous

Calculation of the maximum opening time of the suction valve over the reversal point of the movement of the piston, so that the minimum

Opening time or the minimum opening angle of

Pressure valve is not undershot.

FIG. 6 shows characteristic magnitudes of the controllable valve 1 as a function of the crank angle or the angle of rotation in order to obtain the course of movement B of the valve plate 5b and the course of movement A of the lift-off gripper 6 shown in FIG. In addition, in the curve C, the speed profile of the lift-off gripper 6 is shown. In addition, in the curve G of the

Electromagnet 2a caused force G and to control the

Electromagnet 2a required current H shown. The courses shown in FIG. 6 are particularly important in order to bring about the "gentle landing" of the valve plate 5b on the valve catcher 5c shown in FIG.

FIG. 8 shows schematically another embodiment of a control device 2 for actuating and driving the on the

Suction valve 5 acting gripper 6. The control device 2 comprises a drive device 2n, which is connected via the linearly movably mounted connecting rod 7 with the gripper 6 shown schematically in Figure 7. The drive device 2n shown in this embodiment comprises a linear drive 2w and a electrically controllable damping device 2o, wherein the

Damping device 2o the function has to dampen electrically controlled the movement generated by the linear drive 2w so that the gripper 6 and the valve plate 5b of the suction valve 5 as shown for example in Figure 2 moves. The linear drive 2w has a linearly movable connecting rod 2t, which

is operatively connected to the connecting rod 7. In the illustrated embodiment, the damping device 2o is disposed between the linear drive 2w and the gripper 6. However, the damping device 2o could also be arranged at a different location, in the illustrated view of the control device 2, for example, above the linear drive 2w. The

Damping device 2o can be configured in a variety of ways to effect a damping of the movement of the linear drive 2w. To the inventive "soft landing" of

To effect valve plate 5b on the valve catch 5c, the damping device 2o shown schematically in Figure 8 is particularly

advantageous. The damping device 2o comprises a cylinder 2p and in its interior a linearly displaceable piston 2r which divides the interior of the cylinder 2p into a first inner space 2q and a second inner space 2s. The two inner spaces 2q, 2s are connected to each other via a fluid-conducting connection 2u, so that between the two inner spaces 2q, 2s a fluid

is interchangeable. In an advantageous embodiment, the two inner spaces 2q, 2s are conductively connected to each other via an electrically controllable damping or throttle 2v fluid. A drive and control device 2i is electrically connected via electrical lines 2k, 21 signal to the linear drive 2w and the controllable damping 2v, so that both the linear drive 2w and the damping properties of the damping device 2o are controllable in order to control the position or the speed of the valve plate 5b such that a "gentle landing" of the valve plate 5b is effected as shown by way of example in Figure 2. The control device 2 shown in Figure 8 also comprises a device for determining the stroke and / or the speed of the gripper or the valve plate 5b. This device is not shown in FIG.

The fluid-conducting connection 2u and the electrically controllable damping 2v could also be arranged on the damping device 2o or within the damping device 2o, in particular also on the piston 2r in that the piston 2r has, for example, a fluid-conducting connection between the first and second internal spaces 2q, 2s ,

In a particularly advantageous embodiment, the fluid of the damping device 2o at least partially consists of a

electrorheological or magnetorheological fluid. Such liquids have the property that their viscosity is electrically controllable, so that with such liquids, an electrically controllable throttle section can be configured. Such a throttle section has the advantage that the viscosity can be varied within a wide range, and that the viscosity can be changed very quickly with the aid of the electrical signal. The damping properties of such a damping device 2o are characterized very quickly changed, so that the movement of the piston 2r and thus the movement of the connecting rod 7, the gripper 6 and ultimately the valve plate 5b can be so damped

or can be controlled and regulated, the valve plate 5b with respect to the path traveled and speed a "gentle landing" is carried out.

Damping devices comprising an electrorheological or magnetorheological fluid are known for example from US Pat

Publication WO2008 / 141787A1 or from the publication EP 1034383 Bl known.

The linear drive 2w can, for example, as a hydraulic or pneumatic drive, as an electromagnetic drive, as

Linear motor or be designed as an electric motor with translation.

Claims

1. A method for flow control of a reciprocating compressor by the movement of a closing member (5 b) of an automatic suction valve (5) by means of one of a  Control device (2) driven Abhebegreifers (6) during at least part of a cycle of the crank circuit is affected, the method comprises a continuous backflow control, wherein the lift-off gripper (6) during a first portion (Kl) of the cycle of the crank circle on  Closing member (5b) is applied and prevents its closure, and in which the Abhebegreifer (6) during a second  Part section (K2) of the cycle of the crank circuit is moved back and the closing member (5b) is closed,  and wherein the method comprises a skip control in which the lift-off gripper (6) during a whole cycle of Cranking prevents the closing of the closing member (5b), wherein the flow rate is controlled at least by a combination of continuous backflow control and intermittent control, and wherein the closing member (5b) through the  Control device (2) and the Abhebegreifer (6) is influenced such that a closing member (8b) of a pressure valve (8) of the reciprocating compressor is opened at least during a predetermined total opening angle (Kv) of a crank circle. 2. The method according to claim 1, characterized in that the suction valve (5) is kept open at low flow rate during certain cycles according to the intermittent control, so that the Closing member (8b) of the pressure valve (8) a minimum  Opening angle not lower. 3. The method according to claim 2, characterized in that the predetermined total opening angle (Kv) is at least 10 °, and preferably at least in the range between 20 ° and 30 °. 4. The method according to claim 1, characterized in that the suction valve (5) by the control device (2) and the  Lifting gripper (6) is influenced such that a closing member (8b) of a pressure valve (8) of the reciprocating compressor  is opened at least during a predetermined angular range (.DELTA.) of a crank circle before the upper, respectively lower dead center (OTP, UTP). 5. The method according to claim 4, characterized in that the predetermined angular range (Δ) is at least 10 °, and preferably at least in the range between 20 ° and 30 °. 6. The method according to any one of the preceding claims, characterized in that the pressure profile (P) in the compression chamber of the reciprocating compressor is measured and / or calculated, and that the control device (2) the Abhebegreifer (6) depending on the pressure curve (P) during in each case at least one cycle of the crank circuit in such a way according to the stepless Controlled return flow control or the intermittent control that the pressure curve (P) at least during a predetermined total opening angle (Kv) of a crank circuit has a pressure (P) which is above the opening pressure of the pressure valve (8), so that the pressure valve (8) is automatically opened during the total opening angle (Kv). 7. The method according to any one of the preceding claims, characterized in that the flow rate during a plurality of cycles of the crank circuit only by the stepless  Backflow control or only by the Aussetzregelung is regulated. 8. The method according to any one of the preceding claims, characterized in that the suction valve (5) is operated automatically at a large flow rate during a plurality of successive cycles. 9. The method according to any one of the preceding claims, characterized in that different flow rates are controlled so that the suction valve (5) is operated automatically at high flow rate during certain cycles, and is operated during certain cycles according to the continuous backflow control that the suction valve ( 5) at medium flow rate during each cycle according to the stepless  Backflow control is operated, and that the suction valve (5) at low flow rate during certain cycles according to the Intermittent control is operated, and is operated during certain cycles according to the continuous backflow control. 10. The method according to any one of the preceding claims, characterized in that is regulated in each case after a predetermined number of cycles according to the Aussetzregelung. - - 1 1. A method according to any one of the preceding claims, characterized in that the backflow control is carried out such that the control device (2) comprises an electromagnet (2a) which drives the Abhebegreifer (6), and that the electromagnet (2a) is driven in such a way that the  Lifting gripper (6) during a first section (Kl) of the crank circuit on the closing member (5b) is applied and the  Closure prevents, and that the lift-off gripper (6) during a second portion (K2) of the crank circle the  Movement of the closing member (5b) during closing influenced so that the speed of the moving closing member (5b) is reduced before placing on the suction valve (5). 12. The method according to any one of claims 1 to 10, characterized in that the backflow control is performed such that the control device (2) comprises a drive device (2n), which drives the Abhebegreifer (6), and that the  Drive device (2n) a controllable  Damping device (2o) comprises, which dampens the movement of the Abhebegreifers (6), wherein the drive device (2n) is driven such that the Abhebegreifer (6) during a first portion (Kl) of the crank circuit on the closing member (5b) rests and its closure prevented, and that the lift-off gripper (6) during a second portion (K2) of the crank circuit, the movement of the closing member (5b) during the Closing so influenced that the speed of the moving closing member (5b) is reduced before placing on the suction valve (5). 13. The method of claim 1 1 or 12, characterized  characterized in that the speed of the closing member (5b) during fitting to the suction valve (5) is less than 0, 1 m / s. 14. The method according to any one of claims 1 1 to 13, characterized in that the control device (2) the Abhebegreifer (6) after placing the closing member (5b), during a third portion (K3) of the crank circle, again  accelerated and then brought to a standstill to the  Abhebegreifer (6) from the closing member (5b) to space and bring to an end position. 15. The method according to any one of claims 1 1 to 14, characterized in that the control device (2) comprises an adaptive pilot control, with which the hub (A) and the  Speed (C) of the lift-off gripper (6) is regulated. 16. Reciprocating compressor with flow control,  in particular with stepless flow control, with a at least one automatic suction valve (5) of the compressor arranged Abhebegreifer (6), with a control device (2) for driving the Abhebegreifers (6), as well as with a  Closing member (5b) of the suction valve (5), the Abhebegreifer (6) acts on the closing member (5b), that the suction valve (1) via a controllable part of the working stroke of the compressor is opened, characterized in that the control device (2 ) comprises a drive device (2n), which via a Connecting means (7) acts on the Abhebegreifer (6), wherein the control device (2) a continuous backflow control - zo - comprises, in which the Abhebegreifer (6) during a first portion (Kl) of the cycle of the crank circle on  Closing member (5b) is applied and prevents its closure, and wherein the lift-off gripper (6) during a second  Part (K2) of the cycle of the crank circuit moves back so that the closing member (5b) closes, and wherein the  Control device (2) comprises an intermittent control, wherein the Abhebegreifer (6) during a whole cycle of the  Crank circuit prevents the closing of the closing member (5b). 17. A compressor according to claim 16, characterized in that the drive device (2n) as an electromagnet (2a) is configured. 18. A compressor according to claim 16, characterized in that the drive device (2n) comprises a drive (2w) and a controllable damping device (2o), wherein the Damping device (2o) are designed and arranged such that this dampens the movement of the drive (2w) controllable. 19. A compressor according to any one of claims 16 to 18, characterized in that the control device (2) comprises a device to measure the pressure profile (P) in the compression chamber of the reciprocating compressor and / or to calculate, and that the control device (2 ) is configured such that it operates the closing member (5b) over the Abhebegreifer (6) freewheeling or with backflow control or intermittent control to automatically open the pressure valve (8) during a total opening angle (Kv). - 37 - 20. A compressor according to any one of claims 16 or 19,  characterized in that the control device (2) comprises a sensor (2h) which controls the displacement of the  Drive device (2n) detected, and that the control device (2) is designed such that the drive device (2n), in particular designed as an electromagnet (2a), and thus the Abhebegreifer (6) so controls that the  Delayed speed of the closing member (5b) before placing on the suction valve (5) to gently put the closing member (5b) on the suction valve (5). 21. A compressor according to any one of claims 16 to 20, characterized in that the control device (2i) comprises an adaptive feedforward control device to control signals for the electromagnet (6) from the controlled variables of the stroke (A) and the speed (C) of the Abhebegreifers (6). 2a). 22. A compressor according to any one of claims 16 to 21, characterized in that the electromagnet (2a) is designed as a lifting magnet, with a movable armature (2b), and a fixed magnetic core (2c) with a magnetic coil (2d), wherein the connecting means (7) is fixedly connected to the magnet armature (2b), and wherein the magnet armature (2b) is movably mounted in the running direction of the connecting rod (7). 23. A compressor according to any one of claims 18 to 22, characterized in that the damping device (2o) is configured electrically controllable, and that the damping device (2o) an electrorheological or magnetorheological  Liquid includes.