Rankine cycle system

Abstract

A Rankine cycle system mounted on a vehicle includes a Rankine cycle circuit, a pressure detector, a temperature detector and a controller. The Rankine cycle circuit includes a fluid expansion device, a fluid transferring device, first and second passages, a heater, a cooling device, a bypass passage and a flow regulating valve. The bypass passage connects the first passage and the second passage, and in which the flow regulating valve is provided for opening and closing the bypass passage. The controller is connected to the flow regulating valve for controlling an operation of the flow regulating valve and to the pressure and temperature detectors and for receiving signals of pressure and temperature from the pressure and temperature detectors, respectively. The controller controls the operation of the flow regulating valve based on a superheat degree of the working fluid calculated from the signals of the pressure and temperature.

1 . A Rankine cycle system mounted on a vehicle comprising:
 a Rankine cycle circuit through which working fluid circulates, the Rankine cycle circuit including:
 a fluid expansion device expanding the working fluid for generating work; 
 a fluid transferring device transferring the working fluid to the fluid expansion device; 
 a first passage connecting the fluid transferring device to the fluid expansion device; 
 a second passage connecting the fluid expansion device to the fluid transferring device; 
 a heater provided in the first passage for heating the working fluid; 
 a cooling device provided in the second passage for cooling the working fluid; 
 a bypass passage connecting the first passage to the second passage; and 
 a flow regulating valve provided in the bypass passage for opening and closing the bypass passage, 
   a pressure detector provided in the first passage for detecting a pressure of the working fluid;   a temperature detector provided in the first passage between the heater and the fluid expansion device for detecting the temperature of the working fluid; and   a controller connected to the flow regulating valve for controlling an operation of the flow regulating valve and to the pressure detector and the temperature detector for receiving signals of pressure and temperature from the pressure detector and the temperature detector, the controller controlling the operation of the flow regulating valve based on a superheat degree of the working fluid calculated from the signals of the pressure and the temperature.   
     
     
         2 . The Rankine cycle system according to  claim 1 , wherein the controller causes the flow regulating valve to be opened when the superheat degree of the working fluid is lower than a superheat degree reference value. 
     
     
         3 . The Rankine cycle system according to  claim 2 , wherein the controller controls in such a way that the opening of the flow regulating valve is increased with a decrease of the superheat degree of the working fluid when the superheat degree of the working fluid is smaller than the superheat degree reference value, thereby increasing a flow rate of the working fluid flowing through the bypass passage. 
     
     
         4 . The Rankine cycle system according to  claim 1 , wherein the pressure detector is a communication passage connecting the first passage to the flow regulating valve, the temperature detector is a temperature sensitive cylinder connected to the flow regulating valve and filled with temperature sensitive fluid of the same type of the working fluid circulating in the Rankine cycle circuit in an air-liquid mixture phase, and the flow regulating valve doubles as the controller operated based on a pressure differential between a pressure of the working fluid in the communication passage and a pressure of the temperature sensitive fluid in the temperature sensitive cylinder in accordance with the superheat degree of the working fluid. 
     
     
         5 . The Rankine cycle system according to  claim 4 , wherein the flow regulating valve is operated to be opened when the pressure differential is smaller than a pressure differential reference value. 
     
     
         6 . The Rankine cycle system according to  claim 5 , wherein the opening of the flow regulating valve is increased with a decrease of the superheat degree of the working fluid when the pressure differential is smaller than the second reference value, thereby increasing the flow rate of the working fluid flowing through the bypass passage. 
     
     
         7 . The Rankine cycle system according to  claim 4 , wherein the flow regulating valve includes:
 a valve chamber provided in the bypass passage, the valve chamber including:
 a valve seat; 
 a valve body configured such that the bypass passage is closed when the valve body is seated on the valve seat and the bypass passage is opened when the valve body is moved away from the valve seat; 
 a first spring urging the valve body toward the valve seat for seating the valve body on the valve seat; and 
 a second spring urging the valve body away from the valve seat, 
   a pressure chamber includes:
 a first pressure chamber; 
 a second pressure chamber; and 
 a diaphragm dividing the pressure chamber into the first pressure chamber and the second pressure chamber, 
   a connecting shaft extending through the valve chamber and the pressure chamber and connected to the valve body and the diaphragm, the connecting shaft urged by the second spring.   
     
     
         8 . The Rankine cycle system according to  claim 1 , wherein the bypass passage connects the first passage between the fluid transferring device and the heater to the second passage. 
     
     
         9 . The Rankine cycle system according to  claim 1 , wherein the bypass passage connects the first passage to the second passage between the fluid expansion device and the cooling device. 
     
     
         10 . The Rankine cycle system according to  claim 1 , wherein the bypass passage connects the first passage between the heater and the fluid expansion device to the second passage.