Linear Compressor

Abstract

The present invention discloses a linear compressor in which a piston is driven by a linear motor and linearly reciprocated inside a cylinder to suck, compress and discharge refrigerants. The linear compressor synchronizes an operation frequency of the linear motor with a natural frequency of the piston, considering that an elastic force of a mechanical spring and a gas spring which elastically support the piston in the motion direction is varied by load. Even if the load is varied, the linear motor is operated in the resonance state, to maximize efficiency. The linear compressor varies a stroke of the piston according to the load, thereby actively handling and rapidly overcoming the load and reducing power consumption.

1 . A linear compressor, comprising: a fixed member having a compression space inside; a movable member linearly reciprocated in the fixed member in the axial direction, for sucking refrigerants into the compression space and compressing the refrigerants; one or more springs installed to elastically support the movable member in the motion direction of the movable member, spring constants of which being varied by load; and a linear motor installed to be connected to the movable member, for linearly reciprocating the movable member in the axial direction, and synchronizing its operation frequency with a natural frequency of the movable member dependent upon the spring constants. 
   
   
       2 . The linear compressor of  claim 1 , wherein the spring constants of the springs are varied in proportion to the load, and the operation frequency of the linear motor is varied in proportion to the load. 
   
   
       3 . The linear compressor of  claim 2 , which is installed in a refrigeration/air conditioning cycle, wherein the load is calculated in proportion to a difference between a pressure of condensing refrigerants (condensing pressure) and a pressure of evaporating refrigerants (evaporating pressure) in the refrigeration/air conditioning cycle. 
   
   
       4 . The linear compressor of  claim 3 , wherein the load is additionally calculated in proportion to a pressure that is an average of the condensing pressure and the evaporating pressure (average pressure). 
   
   
       5 . The linear compressor of any one of  claims 1  to  3 , wherein the springs comprise: a mechanical spring being installed to support the movable member at both sides of the motion direction of the movable member, and having a constant mechanical spring constant; and a gas spring having a gas spring constant varied by the load of the refrigerants sucked into the compression space. 
   
   
       6 . The linear compressor of  claim 5 , wherein the mechanical spring and the gas spring are formed so that the ratio of the mechanical spring constant to the total spring constant obtained by adding up the mechanical spring constant and the gas spring constant can be below 90%. 
   
   
       7 . The linear compressor of  claim 5 , wherein the mechanical spring constant and the gas spring constant of the mechanical spring and the gas spring are determined so that the natural frequency of the movable member can be set in a low frequency area between 30 and 55 Hz. 
   
   
       8 . The linear compressor of  claim 5 , wherein the linear motor varies a stroke that is a linear reciprocation distance of the movable member by the load. 
   
   
       9 . The linear compressor of  claim 8 , wherein the linear motor linearly reciprocates the movable member to reach a top dead center even if the stroke of the movable member is varied. 
   
   
       10 . The linear compressor of  claim 9 , wherein an initial position of the movable member is closer to the top dead center according to decrease of the mechanical spring constant. 
   
   
       11 . A linear compressor, comprising: a fixed member having a compression space inside; a movable member linearly reciprocated in the fixed member in the axial direction, for compressing refrigerants sucked into the compression space; a mechanical spring being installed to elastically support the movable member at both sides of the motion direction of the movable member, and having a constant mechanical spring constant; a gas spring having a gas spring constant varied by load of the refrigerants sucked into the compression space; and a linear motor installed to be connected to the movable member, for linearly reciprocating the movable member in the axial direction, wherein the mechanical spring constant and the gas spring constant of the mechanical spring and the gas spring are set so that a stroke that is a linear reciprocation distance of the movable member can be varied by the load. 
   
   
       12 . The linear compressor of  claim 11 , which is installed in a refrigeration/air conditioning cycle, wherein the load is calculated in proportion to a difference between a pressure of condensing refrigerants (condensing pressure) and a pressure of evaporating refrigerants (evaporating pressure) in the refrigeration/air conditioning cycle. 
   
   
       13 . The linear compressor of  claim 12 , wherein the load is additionally calculated in proportion to a pressure that is an average of the condensing pressure and the evaporating pressure (average pressure). 
   
   
       14 . The linear compressor of  claim 11 , wherein the mechanical spring constant and the gas spring constant of the mechanical spring and the gas spring are set so that the movable member can be linearly reciprocated to reach a top dead center even if the stroke of the movable member is varied. 
   
   
       15 . The linear compressor of  claim 14 , wherein an initial position of the movable member is closer to the top dead center according to decrease of the mechanical spring constant.