Reciprocating compressor

Abstract

In a reciprocating compressor with delivery rate control the actuation device ( 3 ) for the valve unloader ( 2 ) of the suction valve ( 1 ) to be held open comprises as drive an electric motor ( 5 ), whose driven element ( 6 ) in conjunction with the non-rotating lifting element ( 10 ) of the valve unloader ( 2 ) and the rolling elements ( 8 ) arranged in between forma ball screw drive. This results in a small-dimensioned, precisely to be regulated actuation device ( 3 ) with high actuating forces and with high motion dynamic.

1 . A reciprocating compressor with capacity control comprising a valve unloader ( 2 ) arranged at at least one automatically acting suction valve ( 1 ) of the compressor, said valve unloader holding open at least the sealing element(s) ( 4 ) of one suction valve ( 1 ) over a portion of the compressor's cycle by means of an electrically operated actuation device ( 3 ), characterized in that wherein the actuation device ( 3 ) comprises as drive an electric motor ( 5 ), whose driven element ( 6 ) comprises a guide surface ( 7 )—extending in a sloped manner in rotational direction—for low-friction rolling elements ( 8 ), which on the other hand interact with a counter-guide ( 9 )—extending in a sloped manner—at a non-rotating lifting element ( 10 ), the latter being connected to the valve unloader ( 2 ). 
   
   
       2 . The compressor in accordance with  claim 1 , wherein the driven element ( 6 ) of the electric motor ( 5 ), in conjunction with the non-rotating lifting element ( 10 ) and the rolling elements ( 8 ) arranged in between, form a ball screw drive. 
   
   
       3 . The compressor in accordance with  claim 1 , wherein the driven element ( 6 ) of the electric motor ( 5 ), in conjunction with the non-rotating lifting element ( 10 ) and the rolling elements ( 8 ) arranged in between, form an inclined ramp drive permitting only limited angular rotation. 
   
   
       4 . The compressor in accordance with  claim 1 , wherein the electric motor ( 5 ) is developed as a brushless direct current motor comprising surface-mounted bandaged permanent magnets ( 12 ). 
   
   
       5 . The compressor in accordance with  claim 2 , wherein the electric motor ( 5 ) comprises a hollow-shaft rotor ( 13 ), in which the nut ( 14 ) of the ball screw drive is integrated. 
   
   
       6 . The compressor in accordance with  claim 5 , wherein the hollow-shaft rotor ( 13 ) comprises a diameter ranging between 30-50 mm, with the incline of the ball screw drive preferably ranging between 6 and 12 mm. 
   
   
       7 . The compressor in accordance with  claim 1 , wherein the elements ( 6 - 10 ) of the rolling element pairings consist at least in part of ceramics. 
   
   
       8 . The compressor in accordance with  claim 1 , wherein additional spring elements ( 18 ) are provided for accelerating and/or braking the movement of the actuation device ( 3 ). 
   
   
       9 . The compressor in accordance with  claim 1 , wherein switching elements ( 20 ) for dynamic braking and for temporary storage and reuse of the electric energy recovered therefrom may be provided in the electric control device ( 19 ) of the electric motor ( 5 ). 
   
   
       10 . The compressor in accordance with  claim 1 , wherein switching elements ( 21 ) for adapting the hold-open force of the actuation device to the respective acting reverse flow force are provided in the electric control device ( 19 ) of the electric motor ( 5 ) by controlling the supply of the electric motor ( 5 ) with current. 
   
   
       11 . A method for controlling the delivery rate of a reciprocating compressor in accordance with  claim 1 , wherein the braking energy to be applied for braking the drive of the actuation device ( 3 ) is generated by the dynamic braking of the electric motor ( 5 ) and the current generated in this process is temporarily stored and reused. 
   
   
       12 . The method in accordance with  claim 11 , wherein the hold-open force of the actuation device ( 3 ) is adjusted to the respective acting reverse flow force by controlling the supply of the electric motor ( 5 ) with current.