JP6394416B2 - Boiling cooler - Google Patents

Description

  The present invention relates to a boiling cooling device.

  Conventionally, for example, Japanese Patent Application Laid-Open No. 2008-248703 discloses a boiling cooling apparatus that cools an engine by using boiling evaporative heat of cooling water flowing in an engine water jacket and collects thermal energy received by the cooling water. Is disclosed. In this boiling cooling device, the water jacket constitutes a part of a closed circuit for circulating the cooling water, and in the middle of the closed circuit, in order to recover the thermal energy of the cooling water (that is, water vapor) vaporized by boiling. In addition to this turbine, a condenser for cooling water vapor and returning it to the cooling water, a catch tank for temporarily storing the cooling water, a pump for sending the cooling water from the catch tank to the water jacket, etc. are provided. .

  Further, a bypass passage is provided in the middle of the above-described closed circuit to connect the condenser to the outlet side of the water jacket by bypassing the turbine. A three-way valve for switching the distribution destination is provided. The distribution destinations of the cooling water and the steam are switched according to the load state of the engine, specifically, the turbine side during low to medium load operation and the bypass passage side during high load operation.

JP 2008-248703 A

  By the way, in the boiling cooling apparatus as described above, in order to maximize the fuel efficiency effect, the engine output shaft (hereinafter also referred to as “engine shaft”) and the turbine shaft may be connected via a reduction gear. desirable. In order to maximize the fuel efficiency in the engine practical range, it is desirable to make the reduction ratio as large as possible so that the turbine efficiency is the best. However, when the engine shaft and the turbine shaft are connected, the turbine rotates at an ultra-high speed in a high engine speed range that is beyond the practical range. Therefore, in such a high engine speed range, the engine shaft and the turbine shaft are connected. It is necessary to disconnect the electromagnetic clutch and the one-way clutch (OWC), to ensure the durability reliability of the turbine, and to suppress the noise vibration.

  Here, in order to continue the above-described engine cooling even after the turbine is disconnected, it is necessary to greatly reduce the wall temperature of the combustion chamber of the engine in contact with the water jacket. The reason for this is that in the high engine speed range, the amount of heat generated by the engine is large, and the volume ratio of water vapor in the water jacket relatively increases. However, in the configuration of the boiling cooling device described above, it is only possible to switch the flow destination of cooling water or water vapor by operating the three-way valve, and it is difficult to sufficiently reduce the wall surface temperature of the combustion chamber.

  In this regard, a gas-liquid separator that separates the water vapor discharged from the outlet side of the water jacket from the cooling water is provided at the above-described three-way valve installation location, and the above-described bypass passage is provided on the gas-phase side of the gas-liquid separator. In addition to providing a flow rate adjusting valve in the bypass passage and disconnecting the turbine to increase the amount of water vapor flowing through the bypass passage by operating the flow rate adjusting valve, the water vapor pressure in the water jacket is increased after the turbine is disconnected. Can be lowered. However, if the water vapor pressure in the water jacket is lowered, the volume ratio of the water vapor described above is further increased, so that it becomes even more difficult for the cooling water to reach the water jacket. Therefore, the inside of the water jacket may overheat and the wall surface temperature of the combustion chamber may increase excessively.

  The present invention has been made to solve the above-described problems. That is, in a boiling cooling device in which a turbine shaft for recovering thermal energy and an output shaft of an engine are connected, an increase in the wall temperature of the combustion chamber is suppressed in a high engine speed range where the connection between the two is released. With the goal.

In order to solve the above problems, the present invention is a boiling cooling apparatus,
A water jacket formed inside the engine and through which the coolant flows,
A gas-liquid separator connected to the outlet side of the water jacket and separating the refrigerant discharged from the water jacket into a gas phase refrigerant and a liquid phase refrigerant and sending the separated liquid phase refrigerant to the inlet side of the water jacket When,
Connected to the gas phase side of the gas-liquid separator and releasably connected to the output shaft of the engine, and rotated by the gas-phase refrigerant separated by the gas-liquid separator, and heat of the gas-phase refrigerant to the output shaft A turbine that transmits energy;
A condenser connected to the outlet side of the turbine for cooling the gas-phase refrigerant and the liquid-phase refrigerant;
A catch tank connected to the outlet side of the capacitor;
A liquid-feeding pump provided in a passage connecting the catch tank and the liquid-phase side of the gas-liquid separator, and sending the liquid-phase refrigerant in the catch tank to the gas-liquid separator;
A pump driving means for driving the liquid feeding pump when the gas-liquid interface of the gas-liquid separator is lower than a predetermined position;
A bypass valve that opens and closes a bypass passage that bypasses the turbine and connects the gas phase side of the gas-liquid separator and the inlet side of the condenser;
Bypass valve control means for operating the bypass valve to open the bypass passage when the rotational speed of the engine is in a predetermined high rotation range;
Release means for disconnecting the turbine from the output shaft while opening the bypass passage;
A liquid discharge valve for opening and closing a liquid discharge passage connecting the liquid phase side of the gas-liquid separator and the inlet side of the capacitor;
While the turbine is disconnected from the output shaft, and when the refrigerant temperature in the water jacket is equal to or higher than the target temperature specified by the rotational speed and load of the engine, the liquid discharge passage is opened. Liquid discharge valve control means for operating the liquid discharge valve;
It is characterized by providing.

  According to the present invention, when the rotational speed of the engine is within a predetermined high rotational speed range, the bypass valve is operated so as to open the bypass passage, and the turbine is separated from the engine shaft. Can be prevented from being supplied to the turbine, and at the same time, the turbine can be prevented from rotating at an extremely high speed by the engine shaft. Also, when the refrigerant temperature in the water jacket is equal to or higher than the target temperature while the turbine is disconnected, the liquid discharge valve is operated to open the liquid discharge passage. Can be discharged. Therefore, the liquid-phase refrigerant cooled by the condenser can be stored in the catch tank, and the gas-liquid interface of the gas-liquid separator can be lowered. Therefore, the liquid pump is driven when the gas-liquid interface becomes lower than the predetermined position, and the cooled liquid-phase refrigerant is sent from the catch tank to the gas-liquid separator, and further from the gas-liquid separator to the inlet side of the water jacket Can be sent to. Therefore, it is possible to suppress an excessive increase in the wall temperature of the combustion chamber when the rotational speed is equal to or higher than a predetermined rotational speed at which the connection between the turbine shaft and the engine shaft is released.

It is a figure for demonstrating the structure of the boiling cooling device of embodiment. It is a flowchart which shows the routine of replenishment control. It is a figure for demonstrating the problem at the time of the opening degree increase of the bypass valve 66. FIG. 4 is a flowchart showing a control routine executed by ECU 80 in the present embodiment.

[Description of device configuration]
Drawing 1 is a figure for explaining the composition of the boiling cooling device of an embodiment. The boiling cooling device 100 shown in FIG. 1 includes a water jacket (not shown) formed inside the engine 10, and the refrigerant circulating in the water jacket receives the heat of the engine 10 and boils. The engine 10 is cooled. In addition, the refrigerant | coolant distribute | circulated in a water jacket will not be specifically limited if it is a working medium which receives the heat of the engine 10 and boils.

  The water jacket is connected above the gas-liquid separator 14 via the refrigerant passage 12. The gas-liquid separator 14 is configured to separate the refrigerant discharged from the outlet side of the water jacket and flowing into the gas-liquid separator 14 into a liquid phase refrigerant and a gas phase refrigerant. One end of the refrigerant passage 16 is connected to the bottom surface of the gas-liquid separator 14. The other end of the refrigerant passage 16 is connected to the inlet side of the water jacket. A liquid feed pump 18 is provided in the refrigerant passage 16. The liquid feed pump 18 is a mechanical pump that uses the crankshaft of the engine 10 as a drive source, but an electric centrifugal pump can also be used. A part of the liquid phase refrigerant in the gas-liquid separator 14 flows into the liquid feed pump 18 via the refrigerant passage 16 and is sent to the inlet side of the water jacket by driving the liquid feed pump 18.

  In addition, the boiling cooling device 100 includes an exhaust heat steam generator 22 downstream of the exhaust catalyst 20 of the engine 10. The exhaust heat steam generator 22 is connected to the gas-liquid separator 14 via the refrigerant passages 24 and 26. When the liquid phase refrigerant in the gas-liquid separator 14 flows into the exhaust heat steam generator 22 via the refrigerant passage 24, a part thereof is vaporized by the exhaust heat. The partially vaporized liquid phase refrigerant flows into the gas-liquid separator 14 from the exhaust heat steam generator 22 via the refrigerant passage 26. The refrigerant flowing into the gas-liquid separator 14 from the refrigerant passage 26 is separated into a liquid-phase refrigerant and a gas-phase refrigerant in the gas-liquid separator 14.

  The boiling cooling apparatus 100 includes a superheater 28, a turbine nozzle 30, and a turbine 32. The superheater 28 is provided between the exhaust catalyst 20 and the exhaust heat steam generator 22. In addition, one end of a refrigerant passage 34 is connected to the superheater 28, and the other end of the refrigerant passage 34 is connected above the gas-liquid separator 14. When the gas-phase refrigerant in the gas-liquid separator 14 flows into the superheater 28 via the refrigerant passage 34, it becomes superheated steam due to the exhaust heat. The superheated steam flows into the turbine nozzle 30 via the refrigerant passage 36 and is sprayed onto the turbine 32. As the superheated steam is sprayed, the turbine 32 rotates. A rotor shaft (turbine shaft) 38 of the turbine 32 is connected to an output shaft (none of which is not shown) of the engine 10 via a speed reducer or a clutch (electromagnetic clutch or OWC), and the rotor shaft 38 is engaged by the engagement of the clutch. While the output shaft is connected, the power generated by the rotation of the turbine 32 is reduced by the speed reducer and transmitted to the output shaft.

  The boiling cooling device 100 includes a condenser 40, a catch tank 42, and a reserve tank 44. The inlet side of the condenser 40 is connected to the turbine 32 via a turbine outlet passage 46, and a turbine outlet valve 48 is provided in the turbine outlet passage 46. By operating the turbine outlet valve 48 to open the turbine outlet passage 46, the gas-phase refrigerant that has passed through the turbine 32 flows into the condenser 40, is cooled in the condenser 40, and returns to the liquid-phase refrigerant. The outlet side of the condenser 40 is connected to the catch tank 42 via the refrigerant passage 50, and the liquid phase refrigerant discharged from the outlet side of the condenser 40 is temporarily stored in the catch tank 42. The catch tank 42 is connected to the reserve tank 44 through a refrigerant passage 52, and an opening / closing valve 54 is provided in the refrigerant passage 52. When the amount of the liquid phase refrigerant in the catch tank 42 is insufficient, the open / close valve 54 is operated to open the refrigerant passage 52, whereby the liquid phase refrigerant in the reserve tank 44 is replenished to the catch tank 42.

  The catch tank 42 is connected to the lower side of the gas-liquid separator 14 via a refrigerant passage 56, and a liquid feed pump 58 and an opening / closing valve 60 are provided in the refrigerant passage 56. Although details will be described later, driving of the liquid feed pump 58 and operation of the on-off valve 60 are performed based on a signal from the liquid level sensor 62. The liquid level sensor 62 emits an ON signal when the liquid level of the gas-liquid separator 14 (that is, the gas-liquid interface) is lower than the position, and emits an OFF signal when the liquid level exceeds the position. It is configured. When the liquid feed pump 58 is driven while the on-off valve 60 is operated to open the refrigerant passage 56, the liquid-phase refrigerant in the catch tank 42 is replenished to the gas-liquid separator 14.

  As described above, the liquid phase refrigerant receives exhaust heat from the engine 10 in the engine 10, the exhaust heat steam generator 22 and the superheater 28, and becomes a high-temperature and high-pressure gas-phase refrigerant. Since the thermal energy of the gas-phase refrigerant is recovered as mechanical power by the rotation of the turbine 32, the fuel consumption of the engine 10 can be improved. The gas-phase refrigerant after passing through the turbine 32 is returned again to the liquid-phase refrigerant in the condenser 40, sent to the gas-liquid separator 14 by driving the liquid feed pump 58, and sent to the water jacket by driving the liquid feed pump 18. Thus, the boiling cooling device 100 also functions as a Rankine cycle system.

  The boiling cooling device 100 includes a bypass passage 64 that bypasses the superheater 28, the turbine nozzle 30, the turbine 32, and the turbine outlet valve 48 to connect the gas-liquid separator 14 and the turbine outlet passage 46. One end of the bypass passage 64 is connected above the gas-liquid separator 14, and the other end of the bypass passage 64 is connected to the turbine outlet passage 46 on the downstream side of the turbine outlet valve 48. A bypass valve 66 and a bypass nozzle 68 are provided in the bypass passage 64. The bypass valve 66 is a pressure relief valve composed of an electromagnetic valve or the like. The bypass valve 66 is operated to open the bypass passage 64 so that the gas-phase refrigerant in the high-pressure side gas-liquid separator 14 passes through the bypass passage 64. As a result, it flows into the condenser 40 on the low pressure side, and the vapor pressure in the gas-liquid separator 14 decreases. The gas-phase refrigerant that has flowed into the condenser 40 is cooled in the condenser 40 and returns to the liquid-phase refrigerant.

  In addition, the boiling cooling device 100 includes a liquid discharge passage 70 for discharging the liquid-phase refrigerant in the gas-liquid separator 14 to the capacitor 40. One end of the liquid discharge passage 70 is connected below the gas-liquid separator 14, and the other end of the liquid discharge passage 70 is connected to the turbine outlet passage 46 downstream of the turbine outlet valve 48. The liquid discharge passage 70 is provided with a liquid discharge valve 72 and a liquid discharge nozzle 74. However, the liquid discharge nozzle 74 can be omitted. The liquid discharge valve 72 is composed of an electromagnetic valve or the like. When the liquid discharge valve 72 is operated to open the liquid discharge passage 70, the liquid-phase refrigerant in the high-pressure side gas-liquid separator 14 passes through the liquid discharge passage 70 to the low pressure side. Flows into the capacitor 40 of FIG. The liquid phase refrigerant that has flowed into the condenser 40 is cooled in the condenser 40.

  Here, the position where the liquid discharge passage 70 is connected to the gas-liquid separator 14 is lower than the position where the liquid level sensor 62 is installed, and the gas-liquid separator 14 is present when the liquid level is present at this position. Even if a large amount of liquid-phase refrigerant is discharged from, the position where the amount of liquid-phase refrigerant that does not hinder the cooling of the engine 10 remains (for example, the bottom surface of the gas-liquid separator 14).

  Further, when the maximum opening degree of the liquid discharge valve 72 is set to the maximum opening degree, the liquid phase refrigerant amount discharged from the gas-liquid separator 14 to the capacitor 40 is less than the maximum discharge amount of the liquid feed pump 58. Set to degrees. The reason for this is that when the amount of the above-described liquid phase refrigerant is larger than the maximum discharge amount, the liquid phase refrigerant in the gas-liquid separator 14 suddenly decreases, and the vapor pressure in the gas-liquid separator 14 or the water jacket increases. This is because the temperature may be lower than the appropriate value and the water jacket may overheat. Instead of setting the maximum opening of the liquid discharge valve 72, the position at which the liquid discharge passage 70 is connected to the gas-liquid separator 14 may always be set below the liquid level by setting the cross-sectional area of the liquid discharge nozzle 74. it can.

  Moreover, the boiling cooling device 100 includes an ECU (Electronic Control Unit) 80. The ECU 80 includes at least an input / output interface, a memory, and a CPU. The input / output interface is provided to capture sensor signals from various sensors and to output operation signals to the actuator. Sensors that the ECU 80 takes in signals include, in addition to the liquid level sensor 62, a temperature sensor 76 that detects the temperature of the refrigerant flowing in the water jacket. Actuators from which the ECU 80 outputs operation signals include a turbine outlet valve 48, on-off valves 54 and 60, a liquid feed pump 58, a bypass valve 66, a liquid discharge valve 72, and the like. The memory stores various control programs, various maps, and the like. The CPU reads out and executes a control program or the like from the memory, and generates an operation signal based on the sensor signal captured by the ECU 80.

[Features of the embodiment]
The control by the ECU 80 includes replenishment control for replenishing the gas-liquid separator 14 with the liquid phase refrigerant in the catch tank 42. This replenishment control is performed based on a signal from the liquid level sensor 62, and is interrupted and executed with priority over other controls (for example, discharge control described later). FIG. 2 is a flowchart showing a replenishment control routine. This routine is repeatedly executed periodically while the engine 10 is in operation.

  In the routine shown in FIG. 2, first, the ECU 80 determines whether or not the liquid level sensor 62 has detected a decrease in the liquid level (step S10). As described above, since the liquid level sensor 62 issues an ON signal when the liquid level of the gas-liquid separator 14 is lower than the position, when the ECU 80 receives the ON signal from the liquid level sensor 62, the liquid level is It can be judged that it is decreasing. If it is determined that the liquid level has decreased, the ECU 80 operates the on-off valve 60 to open the refrigerant passage 56 and drive the liquid feed pump 58 (step S12). On the other hand, when the OFF signal is issued from the liquid level sensor 62, it can be determined that the liquid level is not lowered. Therefore, the ECU 80 operates the on-off valve 60 to close the refrigerant passage 56 and drive the liquid feed pump 58. Stop (step S14).

  By the way, as described above, the rotor shaft 38 is connected to the output shaft of the engine 10, and while the rotor shaft 38 and the output shaft are connected by engagement of the clutch, the power generated by the rotation of the turbine 32 is reduced. And is transmitted to the output shaft. Therefore, the driving of the engine 10 can be assisted to improve the fuel consumption. However, if the rotor shaft 38 and the output shaft are connected, the turbine 32 rotates at an extremely high speed in a high engine rotation range that is greater than the practical range. Therefore, in the present embodiment, in such a high engine speed range, the clutch is released and the turbine outlet valve 48 and the bypass valve 66 are operated to close the turbine outlet passage 46 and open the bypass passage 64. As a result, while the turbine 32 is not rotated, the gas-phase refrigerant in the gas-liquid separator 14 flows through the bypass passage 64 and is sent to the condenser 40 to keep the vapor pressure in the gas-liquid separator 14 at an appropriate value.

  However, in order to continue cooling the engine 10 even after the clutch is released, that is, after the turbine 32 is disconnected, it is necessary to greatly reduce the wall surface temperature of the combustion chamber of the engine 10 in contact with the water jacket. The reason is that the engine 10 generates a large amount of heat in the high engine speed range, and the volume ratio of the gas-phase refrigerant in the water jacket relatively increases. It is.

  Here, if the opening degree of the bypass valve 66 is increased, the vapor pressure in the gas-liquid separator 14 can be greatly reduced, so that the vapor pressure in the water jacket can also be greatly reduced. However, when the vapor pressure in the water jacket is lowered by the operation of the bypass valve 66, the following problem occurs. FIG. 3 is a diagram for explaining a problem when the opening degree of the bypass valve 66 is increased. As shown in FIG. 3, if the opening degree of the bypass valve 66 is increased, the vapor pressure in the water jacket is lowered and the volume ratio of the gas-phase refrigerant is further increased. As a result, the liquid phase refrigerant becomes more difficult to reach the water jacket, and in the part where the liquid phase refrigerant does not reach, cooling by evaporation cannot be performed, and the water jacket may overheat and the temperature of the combustion chamber wall surface may increase excessively. is there.

  Therefore, in the present embodiment, when the temperature of the liquid phase refrigerant in the water jacket after releasing the clutch is equal to or higher than the target temperature, the liquid discharge valve 72 is operated to open the liquid discharge passage 70 and the liquid in the gas-liquid separator 14 The discharge control for discharging the phase refrigerant to the capacitor 40 is executed. When the discharge control is executed, the liquid phase refrigerant of the gas-liquid separator 14 can be discharged to the capacitor 40. Therefore, the liquid phase refrigerant cooled by the condenser 40 can be stored in the catch tank 42, and the liquid level of the gas-liquid separator 14 can be lowered. Therefore, the replenishment control described above is executed when the liquid level becomes lower than the position of the liquid level sensor 62. Therefore, the cooled liquid phase refrigerant can be sent from the catch tank 42 to the gas-liquid separator 14 and further sent from the gas-liquid separator 14 to the inlet side of the water jacket by the liquid feed pump 18. Accordingly, it is possible to prevent the wall temperature of the combustion chamber from rising excessively.

[Specific processing]
Next, specific processing for realizing the above-described functions will be described with reference to FIG. FIG. 4 is a flowchart showing a control routine executed by ECU 80 in the present embodiment. It is assumed that the routine shown in FIG. 4 is executed from the start to the stop of engine 10.

  In the routine shown in FIG. 4, first, the ECU 80 releases the clutch and operates the turbine outlet valve 48, the on-off valves 54 and 60, the bypass valve 66 and the liquid discharge valve 72 to operate the turbine outlet passage 46, the refrigerant passage 52, 56, the bypass passage 64 and the liquid discharge passage 70 are closed (step S20), and it is determined whether or not the engine 10 has been warmed up (step S22). Whether or not the engine 10 has been warmed up is determined based on, for example, whether or not the refrigerant temperature detected by the temperature sensor 76 is equal to or higher than the warm-up temperature (set value). Steps S20 and S22 are repeated until the detected temperature is determined to be equal to or higher than the warm-up temperature.

  If it is determined in step S22 that the detected temperature is equal to or higher than the warm-up temperature, the ECU 80 determines whether the rotational speed of the engine 10 is less than the upper limit rotational speed (set value) in the practical range (step S24). When it is determined that this rotational speed is less than the upper limit rotational speed, the ECU 80 engages the clutch, further operates the turbine outlet valve 48 and the bypass valve 66 to open the turbine outlet passage 46, and the bypass passage 64. Is closed (step S26). Thereby, the Rankine cycle system mentioned above operates. On the other hand, when it is determined that the rotation speed is equal to or higher than the upper limit rotation speed, the ECU 80 proceeds to the processing after step S30.

  Subsequent to step S26, the ECU 80 determines whether or not the rotational speed of the engine 10 is equal to or higher than the upper limit rotational speed (step S28). The processing in this step is the opposite of the processing in step S24. When it is determined that the rotational speed is equal to or higher than the upper limit rotational speed, the ECU 80 operates the turbine outlet valve 48 to close the turbine outlet passage 46 and operates the bypass valve 66 to open the bypass passage 64 (step S30). ), The clutch is released (step S32). The process of step S28 is repeated until it is determined that the rotation speed is equal to or higher than the upper limit rotation speed.

  Subsequent to step S32, the ECU 80 determines whether or not the refrigerant temperature in the water jacket is equal to or higher than a target temperature determined by the rotational speed and load of the engine 10 (step S34). Whether or not the refrigerant temperature in the water jacket is equal to or higher than the target temperature is specifically determined by whether or not the refrigerant temperature detected by the temperature sensor 76 is equal to or higher than the target temperature. The target temperature used in this step is determined in advance based on the engine speed and the engine load, and is stored in the memory of the ECU 80 in a map format.

  If it is determined in step S34 that the refrigerant temperature is equal to or higher than the target temperature, the ECU 80 operates the liquid discharge valve 72 to open the liquid discharge passage 70 for a predetermined period (for example, 1 s) (step S36), and then the engine 10 rotates. It is determined whether or not the speed is equal to or higher than the upper limit rotation speed (step S38). Opening the liquid discharge passage 70 in step S36 is nothing other than executing the above-described drainage control. If the drainage control is executed, the liquid-phase refrigerant of the gas-liquid separator 14 is sent to the condenser 40 to be cooled, The liquid level of the gas-liquid separator 14 can be lowered. Note that the process of step S38 is the same as the process of step S28.

  If it is determined in step S34 that the refrigerant temperature is lower than the target temperature, the ECU 80 operates the liquid discharge valve 72 to close the liquid discharge passage 70 for a predetermined period (for example, 1 s) (step S40), and then in step S38. Execute the process. If it is determined in step S38 that the rotation speed of the engine 10 is equal to or higher than the upper limit rotation speed, the process returns to step S34 to determine whether or not the above-described drainage control can be continued. On the other hand, when it is determined that the rotation speed is less than the upper limit rotation speed, the liquid discharge valve 72 is operated to close the liquid discharge passage 70 (step S42), and the process returns to step S26.

  As described above, according to the routine shown in FIG. 4, after the engine 10 is warmed up, when the rotational speed of the engine 10 is less than the upper limit rotational speed, the output shaft of the engine 10 is connected to the rotor shaft 38 to operate the Rankine cycle system. it can. Further, when the rotation speed of the engine 10 is equal to or higher than the upper limit rotation speed and the refrigerant temperature in the water jacket is equal to or higher than the target temperature, the above-described connection is released and drainage control can be executed. Therefore, the vapor pressure of the gas-liquid separator 14 can be kept at an appropriate value even after the clutch is released. Further, the liquid phase refrigerant of the gas-liquid separator 14 is drained to the capacitor 40 and cooled by the capacitor 40, and the liquid level of the gas-liquid separator 14 can be lowered.

In the embodiment described above, the liquid feed pump 58 corresponds to the “liquid feed pump” of the present invention.
Further, when the ECU 80 executes the process of step S12 of FIG. 2, the “pump drive means” of the present invention executes the process of step S30 of FIG. The “release means” of the present invention is realized by executing the process of step S32 of 4, and the “liquid discharge valve control means” of the present invention is realized by executing the process of step S36 of FIG.

10 Engine 12, 16, 24, 26, 34, 36, 50, 52, 56 Refrigerant passage 14 Gas-liquid separator 32 Turbine 40 Condenser 42 Catch tank 54, 60 On-off valve 58 Liquid feed pump 62 Liquid level sensor 64 Bypass passage 66 Bypass valve 70 Liquid discharge passage 72 Liquid discharge valve 80 ECU
100 Boiling cooler

Claims (1)

A water jacket formed inside the engine and through which the coolant flows,
A gas-liquid separator connected to the outlet side of the water jacket and separating the refrigerant discharged from the water jacket into a gas phase refrigerant and a liquid phase refrigerant and sending the separated liquid phase refrigerant to the inlet side of the water jacket When,
Connected to the gas phase side of the gas-liquid separator and releasably connected to the output shaft of the engine, and rotated by the gas-phase refrigerant separated by the gas-liquid separator, and heat of the gas-phase refrigerant to the output shaft A turbine that transmits energy;
A condenser connected to the outlet side of the turbine for cooling the gas-phase refrigerant and the liquid-phase refrigerant;
A catch tank connected to the outlet side of the capacitor;
A liquid-feeding pump provided in a passage connecting the catch tank and the liquid-phase side of the gas-liquid separator, and sending the liquid-phase refrigerant in the catch tank to the gas-liquid separator;
A pump driving means for driving the liquid feeding pump when the gas-liquid interface of the gas-liquid separator is lower than a predetermined position;
A bypass valve that opens and closes a bypass passage that bypasses the turbine and connects the gas phase side of the gas-liquid separator and the inlet side of the condenser;
Bypass valve control means for operating the bypass valve to open the bypass passage when the rotational speed of the engine is in a predetermined high rotation range;
Release means for disconnecting the turbine from the output shaft while opening the bypass passage;
A liquid discharge valve for opening and closing a liquid discharge passage connecting the liquid phase side of the gas-liquid separator and the inlet side of the capacitor;
While the turbine is disconnected from the output shaft, and when the refrigerant temperature in the water jacket is equal to or higher than the target temperature specified by the rotational speed and load of the engine, the liquid discharge passage is opened. Liquid discharge valve control means for operating the liquid discharge valve;
It is characterized by providing.

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