Method for controlling knocking in a piston compressor

Abstract

A method is disclosed for controlling knocking in a piston compressor and for a piston compressor ( 1 ) that is designed to carry out the method. The method is characterized in that, if a knocking noise made by a piston of the piston compressor hitting a cylinder head is detected by means of a structure-borne noise sensor provided on the piston compressor, the piston stroke of the piston compressor is decreased or, if no knocking noise is detected over a predefinable period of time, the piston stroke is increased.

What we claim is: 
     
         1 . A method for controlling knocking in a piston compressor, wherein a piston oscillates in a cylinder between a first reversal point and a second reversal point along the cylinder axis, wherein the distance between the first reversal point and the second reversal point defines the piston stroke, and wherein a cylinder head is arranged at one end of the cylinder, and wherein the first reversal point lies closer to the cylinder head than the second reversal point,
 characterized in that   the piston stroke is reduced when a knocking noise made by the piston hitting the cylinder head is detected by means of a structure-borne noise sensor arranged on the piston compressor, or that the piston stroke is enlarged when no knocking noise is detected over a predefinable period of time.   
     
     
         2 . The method according to  claim 1 , characterized in that the piston stroke is reduced at least once by a first length when the knocking noise is detected, wherein the piston stroke is reduced by the first length as many times as it takes until the knocking noise is no longer detected. 
     
     
         3 . The method according to  claim 2 , characterized in that the piston stroke is enlarged by a second length when the piston stroke was reduced at least once by the first length wherein the second length is smaller than the first length, and wherein the piston stroke is enlarged by aforesaid second length as many times as it takes until a knocking noise is again detected. 
     
     
         4 . The method according to  claim 1 , characterized in that the piston stroke is enlarged, by the second length, when the knocking noise is not detected over the predefinable period of time, wherein the second length is smaller than the first length, and wherein the piston stroke is enlarged as many times as it takes, by the aforesaid second length, until a knocking noise is detected. 
     
     
         5 . The method according to  claim 3 , characterized in that the piston stroke is further reduced at least once by a third length after the knocking noise is detected again, wherein the piston stroke is reduced by a third length as many times as it takes until the knocking noise is no longer detected. 
     
     
         6 . The method according to  claim 5 , characterized in that the piston stroke is enlarged by a fourth length if the piston stroke was reduced at least once by the third length, wherein the fourth length is smaller than the third length, and wherein the piston stroke is enlarged by the aforesaid fourth length as many times as it takes until a knocking noise is detected again. 
     
     
         7 . The method according to  claim 6 , characterized in that the piston stroke is reduced once by the fourth length after the aforesaid knocking noise was detected. 
     
     
         8 . The method according to  claim 1 , characterized in that the time it takes to reduce and/or enlarge the piston stroke is less than the period duration of the oscillating piston. 
     
     
         9 . A method for adjusting a dead space between a piston and a cylinder head in a piston compressor, characterized in that, in order to adjust a dead space between a piston and a cylinder head in a piston compressor the dead space between the piston and cylinder head is diminished by adding a suitable body as many times as it takes until a knocking noise is detected, wherein, when a knocking noise is detected, the distance between the piston and cylinder head is enlarged as many times as it takes until no more knocking noise is detected. 
     
     
         10 . A piston compressor designed to compress a fluid and dispense it in a compressed state, with
 a cylinder,   a piston arranged in the cylinder that is designed to oscillate in the cylinder between a first reversal point and a second reversal point along the cylinder axis, wherein the distance between the first reversal point and the second reversal point defines a piston stroke, and   a cylinder head arranged at the end of the cylinder, and wherein the first reversal point lies closer to the cylinder head than the second reversal point,   characterized in that   a structure-borne noise sensor arranged on the piston compressor is provided, and designed to detect knocking noises generated by the piston of the piston compressor hitting the cylinder head of the piston compressor, wherein the structure-borne noise sensor is designed to generate a first output signal upon detecting such a knocking noise, wherein a control unit designed to control the piston stroke as a function of the first output signal is provided.   
     
     
         11 . The piston compressor according to  claim 10 , characterized in that the structure-borne noise sensor is arranged on the cylinder head), and constitutes an integral constituent of the cylinder head. 
     
     
         12 . The method according to  claim 9 , characterized in that the suitable body is in the form of a thrust washer. 
     
     
         13 . The method according to  claim 9 , characterized in that the distance between the piston and cylinder head is enlarged by replacing an added thrust washer or an added body with a thinner thrust washer or a thinner body.