Fluid Machine, and Refrigerant Circuit and Waste Heat Utilization Device Using the Fluid Machine

Abstract

[Purpose] To provide a fluid machine, and a refrigerant circuit and a waste heat utilization device using the fluid machine, whereby the size and cost of a Rankine circuit and thus of the waste heat utilization device can be reduced while preventing an abnormally high pressure from being developed in the Rankine circuit and also improving starting performance of the Rankine circuit. [Means for Attaining the Purpose] A waste heat utilization device ( 1 ) is provided with a Rankine circuit ( 4 ) including a fluid machine ( 10 ). The fluid machine ( 10 ) includes, inside a housing thereof, a drive section ( 22 ) configured to be driven by a working fluid introduced from an inlet port ( 33 ) and to discharge the working fluid to an outlet port ( 45 ), a communication passage ( 102 ) allowing the working fluid to flow from the inlet port into the drive section, a bypass passage ( 104 ) allowing the working fluid to flow from the inlet port to the outlet port while bypassing the drive section, and a valve mechanism ( 106, 112, 124 ) configured to block inflow of the working fluid from the inlet port and to allow the inlet port to be connected selectively to the communication passage and the bypass passage.

1 . A fluid machine comprising, inside a housing thereof:
 a drive section configured to be driven by a working fluid introduced from an inlet port of the fluid machine, and to discharge the working fluid to an outlet port of the fluid machine;   a communication passage allowing the working fluid to flow from the inlet port into the drive section;   a bypass passage allowing the working fluid to flow from the inlet port to the outlet port while bypassing the drive section; and   a valve mechanism configured to block inflow of the working fluid from the inlet port and to allow the inlet port to be connected selectively to the communication passage and the bypass passage.   
     
     
         2 . A refrigerant circuit comprising the fluid machine of  claim 1  inserted in a circulation path for circulating the working fluid. 
     
     
         3 . A waste heat utilization device comprising, as the refrigerant circuit of  claim 2 , a Rankine circuit including an expansion unit inserted in the circulation path, the expansion unit being contained in the housing of the fluid machine and configured to produce drive force by causing the drive section to expand the working fluid whose pressure has been increased by waste heat of a heat source,
 wherein the Rankine circuit further includes a high-pressure path section which is connected to the inlet port and in which high pressure of the working fluid circulated through the circulation path prevails, a low-pressure path section which is connected to the outlet port and in which low pressure of the working fluid circulated through the circulation path prevails, and pressure holding means for holding the pressure in the high-pressure path section, and   wherein, when the pressure holding means is in operation, the valve mechanism blocks the inflow of the working fluid from the inlet port, and when the pressure in the high-pressure path section is higher than or equal to a first preset pressure, the valve mechanism allows the inflow of the working fluid from the inlet port and connects the inlet port to the bypass passage or the communication passage.   
     
     
         4 . The waste heat utilization device according to  claim 3 , wherein:
 when the Rankine circuit is in operation, the valve mechanism connects the inlet port to the communication passage,   when the Rankine circuit is stopped, the valve mechanism operates the pressure holding means to block the inflow of the working fluid from the inlet port,   when the pressure in the high-pressure path section is higher than or equal to the first preset pressure, the valve mechanism allows the inflow of the working fluid from the inlet port and connects the inlet port to the bypass passage or the communication passage, and   when the Rankine circuit is restarted after being stopped, the valve mechanism connects the inlet port to the communication passage.   
     
     
         5 . The waste heat utilization device according to  claim 3 , wherein:
 when the Rankine circuit is in operation, the valve mechanism connects the inlet port to the communication passage,   when the pressure in the high-pressure path section is lower than a second preset pressure during the operation of the Rankine circuit, the valve mechanism operates the pressure holding means to block the inflow of the working fluid from the inlet port, and   when the pressure in the high-pressure path section is higher than or equal to a third preset pressure, the valve mechanism allows the inflow of the working fluid from the inlet port and connects the inlet port to the communication passage.   
     
     
         6 . The waste heat utilization device according to  claim 3 , wherein, when the pressure in the high-pressure path section is higher than or equal to the first preset pressure, the valve mechanism allows the inflow of the working fluid from the inlet port and connects the inlet port only to the bypass passage. 
     
     
         7 . The waste heat utilization device according to  claim 3 , wherein the valve mechanism includes a valve element which allows the inlet port to selectively communicate with the communication passage and the bypass passage and on which the high pressure of the working fluid in the inlet port acts, and a spring mechanism supporting the valve element and pressing the valve element against the high pressure of the working fluid, to block and allow the inflow of the working fluid from the inlet port. 
     
     
         8 . The waste heat utilization device according to  claim 7 , wherein the spring mechanism includes a spring pushing the valve element, and an accommodation chamber accommodating the spring and sealed in a gastight fashion with respect to the inlet port. 
     
     
         9 . The waste heat utilization device according to  claim 8 , wherein:
 the accommodation chamber communicates with the outlet port, and   when a force exerted on the valve element by the high pressure of the working fluid in the inlet port is larger than a sum of a force exerted by the low pressure of the working fluid in the outlet port and a pushing force exerted by the spring, the spring mechanism allows the inflow of the working fluid from the inlet port and connects the inlet port to the bypass passage.   
     
     
         10 . The waste heat utilization device according to  claim 8 , wherein:
 the accommodation chamber is open to atmosphere, and   when a force exerted on the valve element by the high pressure of the working fluid in the inlet port is larger than a sum of a force exerted by an atmospheric pressure and a pushing force exerted by the spring, the spring mechanism allows the inflow of the working fluid from the inlet port and connects the inlet port to the bypass passage.   
     
     
         11 . The waste heat utilization device according to  claim 7 , wherein the valve element is a ball valve element or a rotary valve element and is rotated by a predetermined drive source. 
     
     
         12 . The waste heat utilization device according to  claim 4 , wherein
 when the Rankine circuit is in operation, the valve mechanism connects the inlet port to the communication passage,   when the pressure in the high-pressure path section is lower than a second preset pressure during the operation of the Rankine circuit, the valve mechanism operates the pressure holding means to block the inflow of the working fluid from the inlet port, and   when the pressure in the high-pressure path section is higher than or equal to a third preset pressure, the valve mechanism allows the inflow of the working fluid from the inlet port and connects the inlet port to the communication passage.