Power transmission device of a compressor

Abstract

A power transmission device of a compressor includes a rotary shaft, a pulley, a hub, a power shutoff member, a spacer and a cylinder. The power shutoff member shuts off excessive torque transmission between the pulley and the rotary shaft of the compressor. The spacer is disposed on the rotary shaft. The cylinder is disposed between the power shutoff member and the rotary shaft. The cylinder has an external thread portion formed at the outer periphery thereof for engagement with an internal thread portion of the power shutoff member and an internal thread portion formed at the inner periphery thereof for engagement with an external thread portion of the rotary shaft. The cylinder has a contacting surface for contact with a seating surface of the spacer and a seating surface for contact with a contacting surface of the hub at the axial end portion of the hub.

1 . A power transmission device of a compressor comprising:
 a rotary shaft rotatably supported by a casing of the compressor, the rotary shaft having an external thread portion;   a pulley rotatably mounted on the casing;   a hub connected to the pulley for rotation therewith;   a power shutoff member joined to the hub, the power shutoff member being interposed between the hub and the rotary shaft, the power shutoff member having an internal thread portion, the power shutoff member shutting off excessive torque transmission between the pulley and the rotary shaft;   a spacer disposed on the rotary shaft, the spacer having a seating surface; and   a cylinder disposed between the power shutoff member and the rotary shaft, the cylinder having an external thread portion formed at the outer periphery thereof for engagement with the internal thread portion of the power shutoff member and an internal thread portion formed at the inner periphery thereof for engagement with the external thread portion of the rotary shaft, the cylinder having a contacting surface for contact with the seating surface of the spacer and a seating surface for contact with a contacting surface of the hub at the axial end portion of the hub.   
   
   
       2 . The power transmission device of the compressor according to the  claim 1 , wherein the radial distances from the axis of the rotary shaft to the contacting surface of the cylinder for contact with the seating surface of the spacer and from the axis of the rotary shaft to the contacting surface of the hub for contact with the seating surface of the cylinder are different each other. 
   
   
       3 . The power transmission device of the compressor according to the  claim 2 , wherein the radial distance from the axis of the rotary shaft to the contacting surface of the hub is smaller than that from the axis of the rotary shaft to the contacting surface of the cylinder. 
   
   
       4 . The power transmission device of the compressor according to the  claim 1 , wherein at least either the coefficients of friction between the power shutoff member and the cylinder and between the cylinder and the rotary shaft are different or the coefficients of friction between the contacting surface of the hub and the seating surface of the cylinder and between the contacting surface of the cylinder and the seating surface of the spacer are different. 
   
   
       5 . The power transmission device of the compressor according to the  claim 4 , wherein the coefficient of friction between the power shutoff member and the cylinder is smaller than the coefficient of friction between the cylinder and the rotary shaft, and the coefficient of friction between the contacting surface of the hub and the seating surface of the cylinder is smaller than the coefficient of friction between the contacting surface of the cylinder and the seating surface of the spacer. 
   
   
       6 . The power transmission device of the compressor according to the  claim 5 , wherein lubricant is applied between the power shutoff member, and the cylinder and between the contacting surface of the hub and the seating surface of the cylinder. 
   
   
       7 . The power transmission device of the compressor according to the  claim 4 , wherein the coefficient of friction between the power shutoff member and the cylinder is larger than the coefficient of friction between the cylinder and the rotary shaft, and the coefficient of friction between the contacting surface of the hub and the seating surface of the cylinder is larger than the coefficient of friction between the contacting surface of the cylinder and the seating surface of the spacer. 
   
   
       8 . The power transmission device of the compressor according to the  claim 7 , wherein lubricant is applied between the cylinder and the rotary shaft and between the contacting surface of the cylinder and the seating surface of the spacer. 
   
   
       9 . The power transmission device of the compressor according to the  claim 4 , wherein the power shutoff member and the hub are made of a material which has a different coefficient of friction from the coefficient of friction of the rotary shaft and the cylinder. 
   
   
       10 . The power transmission device of the compressor according to the  claim 1 , wherein the carbon dioxide is used as a refrigerant gas in the compressor.