Capacity control of a compressor

Abstract

A linear compressor that is operated at a frequency greater than the natural frequency of the spring-mass system of the compressor. Operating the compressor at such a frequency can increase the output of the compressor. In one embodiment, the linear compressor includes a cylinder block having a cylinder bore, a piston positioned within the cylinder bore, first and second springs for positioning the piston where the piston and the first and second springs comprise the spring-mass system, and an armature operably engaged with the piston to drive the piston at a frequency greater than the natural frequency of the spring-mass system. The linear compressor can also include a controller which monitors the instantaneous natural frequency of the spring-mass system and modulates the frequency of the current passing through the armature such that it exceeds the natural frequency of the spring-mass system.

1 . A linear compressor, comprising: 
 a cylinder block having a cylinder bore;    a piston, wherein at least a portion of said piston is positioned within said cylinder bore;    a first spring for positioning said piston, said piston and said first spring comprising a spring-mass system having a natural frequency;    an armature operably engaged with said piston to drive said piston at a driving frequency; and    a controller for increasing said driving frequency above said natural frequency.    
   
   
       2 . The linear compressor of  claim 1 , further comprising a sensor for measuring the frequency of electrical current flowing through said armature, said sensor in communication with said controller.  
   
   
       3 . The linear compressor of  claim 1 , further comprising a sensor for measuring one of the temperature and the pressure of a refrigerant compressed by said compressor.  
   
   
       4 . A method for operating a linear compressor, comprising the steps of: 
 providing a cylinder block having a cylinder bore, a piston positioned within said cylinder bore, and at least one spring for positioning said piston, said piston and said at least one spring comprising a spring-mass system having a natural frequency;    applying a driving force to said piston to drive said piston within said cylinder bore at a driving frequency; and    increasing said driving frequency above said natural frequency, whereby said increasing step increases the capacity of said linear compressor.    
   
   
       5 . The method of  claim 2 , further comprising the step of monitoring said natural frequency.