Method for Controlling Delivery Quantity, and Reciprocating Compressor Having Delivery Quantity Control

Abstract

The invention relates to a method for the delivery quantity control of a reciprocating compressor, wherein the motion of a closing organ ( 5 b ) 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 ( 5 b ) and prevents the same from closing during a first partial segment (K 1 ) of the cycle of the crankshaft, and wherein the retraction gripper ( 6 ) is retracted during a second partial segment (K 2 ) of the cycle of the crankshaft and the closing organ ( 5 b ) is closed, and wherein the method comprises an interruption control, wherein the retraction gripper ( 6 ) prevents the closing organ ( 5 b ) 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 ( 5 b ) is influenced by the control device ( 2 ) and the retraction gripper ( 6 ) such that a closing organ ( 8 b ) of a pressure valve ( 8 ) of the reciprocating compressor is opened at least during a prescribed total opening angle (Kv) of a crankshaft.

1 . Method for delivery quantity control of a reciprocating compressor, in which movement of a closing body ( 5   b )of a self-acting intake valve ( 5 ) is influenced during at least part of a cycle of crank rotation by an unloader ( 6 ) driven by a control device ( 2 ), wherein the method comprises using a continuously variable backflow regulation, in which the unloader ( 6 ) lies against the closing body ( 5   b )during a first section (K 1 ) of the cycle of crank rotation and prevents its closure, and in which the unloader ( 6 ) is driven back during a second section (K 2 ) of the cycle of crank rotation and the closing body ( 5   b )is closed, and wherein the method further comprises using a skip regulation, in which the unloader ( 6 ) prevents closure of the closing body ( 5   b ) during a whole cycle of crank rotation, wherein the delivery quantity is regulated by at least a combination of continuously variable backflow regulation and skip regulation, and that during use of the continuously variable backflow regulation wherein the closing body ( 5   b )is influenced by the control device ( 2 ) and the unloader ( 6 ) in such a way that a closing body ( 8   b ) of a pressure valve ( 8 ) of the reciprocating compressor is opened during at least a predetermined minimal total opening angle (Kv) of a crank rotation. 
     
     
         2 . Method according to  claim 1 , wherein for small delivery quantities, the intake valve ( 5 ) is held open under skip regulation during certain cycles, whereby the closing body ( 8   b ) of the pressure valve ( 8 ) does not fall below a minimal opening angle. 
     
     
         3 . Method according to  claim 2 , wherein the predetermined total opening angle (Kv) is at least 10°. 
     
     
         4 . Method according to  claim 3 , wherein the intake valve ( 5 ) is influenced by the control device ( 2 ) and the unloader ( 6 ) in such a way that a closing body ( 8   b ) of a pressure valve ( 8 ) of the reciprocating compressor is opened at least during a predetermined angular range (Δ) of a crank rotation before the upper, respectively lower dead centre (OTP, UTP). 
     
     
         5 . Method according to  claim 4 , wherein the predetermined angular range (Δ) is at least 10°. 
     
     
         6 . Method according to  claim 1  wherein the progression of pressure (P) in the compression space of the reciprocating compressor is measured and/or calculated, and that the control device ( 2 ) steers the unloader ( 6 ) in dependence on the progression of pressure (P), on each occasion during at least a cycle of crank rotation, under constantly variable backflow regulation or skip regulation in such a way that the progression of pressure (P) has a pressure (P) at least during a predetermined total opening angle (Kv) of a crank rotation which lies above the opening pressure of the pressure valve ( 8 ), such that the pressure valve ( 8 ) is automatically opened during the total opening angle (Kv). 
     
     
         7 . Method according to  claim 1  wherein during a plurality of cycles of crank rotation, the delivery quantity is regulated only by constantly variable backflow regulation or only by skip regulation. 
     
     
         8 . Method according to  claim 1  wherein for large delivery quantities, the intake valve ( 5 ) is driven automatically during a plurality of successive cycles. 
     
     
         9 . Method according to  claim 1  wherein various delivery quantities are regulated in such a way, that, for large delivery streams, the intake valve ( 5 ) is automatically driven during certain cycles and is driven with constantly variable backflow regulation during certain cycles;
 that, that, for middle-sized delivery quantities, the intake valve ( 5 ) is driven during every cycle with constantly variable backflow regulation; and that, for small delivery quantities, the intake valve ( 5 ) is constantly held open during certain cycles under skip regulation, and driven with constantly variable backflow regulation during certain cycles. 
 
     
     
         10 . Method according to  claim 1  wherein each time after a predetermined number of cycles regulation is carried out under skip regulation. 
     
     
         11 . Method according to  claim 1  wherein the backflow regulation occurs in such a way that the control device ( 2 ) comprises an electromagnet ( 2   a ) which drives the unloader ( 6 ), and that the electromagnet ( 2   a ) is steered in such a way that the unloader ( 6 ) lies against the closing body ( 5   b )during a first section (K 1 ) of the crank rotation and prevents its shutting, and that the unloader ( 6 ) influences the movement of the closing body ( 5   b ) during shutting during a second section (K 2 ) of the crank rotation in such a way that the speed of the moving closing body ( 5   b )is reduced prior to seating on the intake valve ( 5 ). 
     
     
         12 . Method according to  claim 1  wherein the backflow regulation occurs in such a way that the control device ( 2 ) comprises a drive mechanism ( 2   n ), which drives the unloader ( 6 ), and that the drive mechanism ( 2   n ) comprises a steerable damping mechanism ( 2   o ) which damps dampens the movement of the unloader ( 6 ), wherein the drive mechanism ( 2   n ) is steered in such a way that the unloader ( 6 ) lies against the closing body ( 5   b ) during a first section (K 1 ) for the crank rotation and prevents its shutting, and that the unloader ( 6 ) influences the movement of the closing body ( 5   b )during shutting during a second section (K 2 ) of the crank rotation in such a way that the speed of the moving closing body ( 5   b ) is reduced prior to seating on the intake valve ( 5 ). 
     
     
         13 . Method according to  claim 11  or  12 , wherein during seating on the intake valve ( 5 ), the speed of the closing body ( 5   b )is less than 0.1 m/s. 
     
     
         14 . Method according to  claim 11  or  12  wherein after the seating of the closing body ( 5   b ), during a third section (k 3 ) of the crank rotation, the control device ( 2 ) once again accelerates the unloader ( 6 ) and then brings it to rest, in order to distance the unloader ( 6 ) from the closing body ( 5   b ) and to bring the unloader ( 6 ) to an end position. 
     
     
         15 . Method according to  claim 11  or  12  wherein the control device ( 2 ) comprises an adaptive pre-control with which the stroke (A) and the speed (C) of the unloader ( 6 ) are regulated. 
     
     
         16 . Reciprocating compressor with delivery quantity regulation with constantly variable delivery quantity regulation, with an unloader ( 6 ) arranged on at least one self-acting intake valve ( 5 ) of the compressor, with a control device ( 2 ) for driving the unloader ( 6 ), and with a closing body ( 5   b ) of the intake valve ( 5 ), wherein the unloader ( 6 ) is configured to act on the closing body ( 5   b ) in such a way that the intake valve ( 5 ) is opened over a controllable part of the working stroke of the compressor, wherein the control device ( 2 ) comprises a drive mechanism ( 2   n ) which is configured to act via a connection element means ( 7 ) on the unloader ( 6 ), and wherein the control device ( 2 ) comprises a constantly variable backflow regulation, in which the unloader ( 6 ) is configured to lie against the closing body ( 5   b ) during a first section (K 1 ) of the cycle of crank rotation and prevents its shutting, and in which the unloader ( 6 ) is configured to return during a second section (K 2 ) of the cycle of crank rotation such that the closing body ( 5   b )shuts, and wherein the control device ( 2 ) is configured such that it also comprises a skip regulation, in which the unloader ( 6 ) prevents the shutting of the closing body ( 5   b )during a complete cycle of crank rotation, and that the control device ( 2 ) is configured such that the unloader ( 6 ) may be operated by two different methods, the continuously variable backflow regulation and the skip regulation. 
     
     
         17 . Compressor according to  claim 16 , wherein the drive mechanism ( 2   n ) is in the form of an electromagnet ( 2   a ). 
     
     
         18 . Compressor according to  claim 16 , wherein, the drive mechanism ( 2   n ) comprises a drive ( 2   w ) and a steerable damping mechanism ( 2   o ), wherein the damping mechanism ( 2   o ) is adapted and arranged such that it damps the movement of the drive ( 2   w ). 
     
     
         19 . Compressor according to  claim 16  wherein the control device ( 2 ) comprises a mechanism for measuring and/or calculating the pressure progression (P) in the compression space of the reciprocating compressor, and that the control device ( 2 ) is configured such that it drives the closing body ( 5   b ) via the unloader ( 6 ) in free-running mode or with backflow regulation or with skip regulation, in order to open the pressure valve ( 8 ) automatically during a total opening angle (Kv). 
     
     
         20 . Compressor according to  claim 16  wherein the control device ( 2 ) comprises a sensor ( 2   h ), which is configured to measure a displacement of the drive mechanism ( 2   n ), and that the control device ( 2 ) is further configured such that it steers the drive mechanism ( 2   n ), and thereby the unloader ( 6 ) in such a way that the speed of the closing body ( 5   b ) retards prior to seating on the intake valve ( 5 ), in order to seat the closing body ( 5   b ) with reduced velocity on the intake valve ( 5 ). 
     
     
         21 . Compressor according to  claim 17  wherein the regulation mechanism ( 2   i ) comprises an adaptive precontrol mechanism in order to generate control signals for the electromagnets ( 2   a ) from the control variables of the stroke (A) and the speed (C) of the unloader ( 6 ). 
     
     
         22 . Compressor according to  claim 17  wherein the electromagnet ( 2   a ) is a solenoid, with a movable magnet anchor ( 2   b ) and a fixedly arranged magnet core ( 2   c ) with magnet coil ( 2   d ), wherein a connection element ( 7 ) is fixedly connected with the magnet anchor ( 2   b ), and wherein the magnet anchor ( 2   b ) is mounted so as to be movable in the direction of extension of the connection means ( 7 ). 
     
     
         23 . Compressor according to  claim 18  wherein the damping mechanism ( 2   o ) is electrically steerable, and that the damping mechanism ( 2   o ) comprises an electrorheological or magnetorheological liquid.