Centrifugal compressor and supercharger comprising same

Abstract

A housing is formed with an impeller side communicating passage extending from an impeller chamber in a direction including a component of an outer side in a radial direction, circulating channels extending from the impeller side communicating passage in a direction including a component of a front side in the axial direction, and a suction side communicating passage communicating with the circulating channel and a suction channel that guides a gas into the impeller chamber. A radial dimension from an axis to a communicating position at which each of the circulating channels communicates with the suction side communicating path is larger than a radial dimension from the axis to a communication position with the impeller side communicating path in the circulating channel. A channel area of the circulating passage at a communicating position for the suction side communicating passage is larger than a channel area of the circulating channel at a communicating position for the impeller side communicating passage.

1 . A centrifugal compressor comprising
 a rotary shaft configured to rotate about an axis;   an impeller mounted on an outer circumference of the rotary shaft; and   a housing configured to cover the impeller,   wherein the impeller has a hub mounted on the rotary shaft and a plurality of blades,   wherein the plurality of blades are provided on the hub at intervals in a circumferential direction centered on the axis,   and the plurality of blades are configured to be rotated integrally with the hub and guide a gas, which flows from a front side in an axial direction which is one side in an axial direction in which the axis extends, to an outer side in a radial direction relative to the axis,   wherein the housing is formed with a suction channel, an impeller chamber, a discharge channel, an impeller side communication passage, circulating channels, and a suction side communication passage,   wherein the suction channel is configured to guides the gas to the front side in the axial direction of the impeller,   wherein the impeller chamber communicates with the suction channel and houses the impeller,   wherein the discharge channel communicates with the impeller chamber and is configured to flow into the gas sent from the impeller to the outer side in the radial direction,   wherein the impeller side communication passage communicates with the impeller chamber and extends from the impeller chamber in a direction including a component of the outer side in the radial direction,   wherein the circulating channels communicate with the impeller side communication passage and extend from the impeller side communication passage in a direction including a component of the front side in the axial direction,   wherein the suction side communication passage communicates with the circulating channels and the suction channel, and   wherein a suction side diameter dimension, which is a radial dimension in the radial direction from the axis to a communicating position at which each of the circulating channels communicates with the suction side communication passage, is greater than an impeller side diameter dimension, which is a radial dimension in the radial direction from the axis to a communicating position at which each of the circulating channels communicates with the impeller side communication passage, and   a channel area of each of the circulating channels at the communicating position for the suction side communication passage is greater than that of each of the circulating channels at the communicating position for the impeller side communication passage.   
     
     
         2 . The centrifugal compressor according to  claim 1 , wherein the housing is formed with the plurality of circulating channels and partition parts,
 wherein the plurality of circulating channels are arranged in the circumferential direction centered on the axis,   wherein the partition parts divide circulating channels adjacent to each other in the circumferential direction.   
     
     
         3 . The centrifugal compressor according to  claim 1 , wherein:
 the suction channel is formed in a shape that is rotationally symmetric around the axis and has a diameter-reduced part in which a channel area thereof is gradually reduced toward a back side in the axial direction which is the other side in the axial direction; and   a communication port of the suction side communication passage for the suction channel is formed in a face defining a channel at the diameter-reduced part.   
     
     
         4 . The centrifugal compressor according to  claim 3 , wherein the face defining the channel at the diameter-reduced part forms a curved surface protruding to a side close to the axis. 
     
     
         5 . The centrifugal compressor according to  claim 3 , wherein a radial dimension in the radial direction from the axis to an edge of the communication port of the suction side communication passage at the front side in the axial direction is smaller than the suction side diameter dimension and is greater than the impeller side diameter dimension. 
     
     
         6 . The centrifugal compressor according to  claim 1 , wherein the suction side communication passage is folded back from a boundary between the circulating channel and the suction side communication passage and then extends toward a back side in the axial direction which is the other side in the axial direction, to communicate with the suction channel while being directed to an inner side in the radial direction relative to the axis. 
     
     
         7 . The centrifugal compressor according to  claim 1 , wherein, when
 L is defined as an axial dimension in the axial direction from the communicating position at which each of the circulating channels communicates with the suction side communication passage to the communicating position at which each of the circulating channels communicates with the impeller side communication passage,   do is defined as an equivalent diameter related to the channel area of each of the circulating channels at the communicating position for the suction side communication passage, and   di is defined as an equivalent diameter related to the channel area of each of the circulating channels at the communicating position for the impeller side communication passage,   a spread angle (2θ) defined by a formula below is less than 20°.
   2θ=2×tan(( do−di )/2 L )<20°.
 
   
     
     
         8 . The centrifugal compressor according to  claim 1 , wherein an axial dimension in the axial direction from the communicating position at which each of the circulating channels communicates with the suction side communication passage to the communicating position at which each of the circulating channels communicates with the impeller side communication passage is greater than or equal to 0.25 times an impeller outer diameter that is a maximum outer diameter of the impeller. 
     
     
         9 . A supercharger comprising:
 the centrifugal compressor according to  claim 1 ; and   a turbine,   the turbine has
 a turbine rotary shaft configured to rotate about the axis, 
 a turbine impeller mounted on an outer circumference of the turbine rotary shaft, and 
 a turbine housing configured to convert the turbine impeller, 
   the turbine rotary shaft and the rotary shaft of the centrifugal compressor are located on the same axis, are mutually coupled, are integrally rotated, and form a supercharger rotary shaft.