JP6237486B2 - Boiling cooler - Google Patents

Description

  The present invention relates to a boiling cooling device.

  As a cooling device for an internal combustion engine, a boiling cooling device that performs cooling by using the boiling vaporization heat of a refrigerant flowing in a refrigerant passage (for example, a water jacket) formed inside the internal combustion engine is known. In the boiling cooling device, for example, a gas-liquid separator is connected to the refrigerant passage. The gas-liquid separator separates the refrigerant discharged from the refrigerant passage into a liquid phase refrigerant and a gas phase refrigerant. The liquid phase refrigerant separated by the gas-liquid separator is sent to the internal combustion engine to be cooled by the water pump. For example, Patent Document 1 is known as a proposal in which such a boiling cooling device is combined with a Rankine cycle.

JP 2010-285893 A

  By the way, when steam generated by the boiling cooling device incorporated in the internal combustion engine is used in the Rankine cycle, an expander such as a turbine is driven by the gas-phase refrigerant after passing through the gas-liquid separator. For this reason, if the liquid-phase refrigerant is contained in the gas-phase refrigerant after passing through the gas-liquid separator, the expander may be damaged. If the amount of the liquid-phase refrigerant in the gas-liquid separator is not properly managed, it is considered that the possibility that the liquid-phase refrigerant is mixed into the gas-phase refrigerant after passing through the gas-liquid separator is increased.

  Therefore, an object of the boiling cooling device disclosed in this specification is to appropriately control the amount of the liquid-phase refrigerant in the gas-liquid separator.

  In order to solve such a problem, a boiling cooling device disclosed in the present specification includes an internal combustion engine that is cooled by boiling a refrigerant flowing in a refrigerant passage formed therein, and the internal combustion engine and an expander. And a gas-liquid separator that separates the refrigerant discharged from the internal combustion engine into a liquid-phase refrigerant and a gas-phase refrigerant, and a liquid level that measures the liquid level in the gas-liquid separator A sensor, a condenser disposed downstream of the expander and cooling the gas-phase refrigerant that has passed through the expander to form a liquid-phase refrigerant; and a catch tank that stores the liquid-phase refrigerant cooled by the capacitor; , A refrigerant discharge passage for discharging the liquid phase refrigerant in the gas-liquid separator to the catch tank, a control valve provided in the refrigerant discharge passage, and opening / closing of the control valve based on a measured value of the liquid level sensor A control unit for performing control . Thereby, the quantity of the liquid phase refrigerant | coolant in a gas-liquid separator can be controlled, and it can suppress that a liquid phase refrigerant mixes with the vapor | steam supplied to an expander, ie, a gaseous-phase refrigerant | coolant.

  The boiling cooling device disclosed in the present specification is provided in a refrigerant supply passage for supplying the liquid-phase refrigerant in the catch tank to the gas-liquid separator, and in the refrigerant supply passage, and the measured value of the liquid level sensor. And a water pump that is driven and controlled by the control unit. The amount of liquid phase refrigerant in the gas-liquid separator can be controlled more appropriately.

  The catch tank may be connected to a negative pressure system. Thereby, the pressure in the catch tank can be quickly reduced, and the liquid-phase refrigerant in the gas-liquid separator can be discharged to the catch tank due to the pressure difference from the gas-liquid separator.

  According to the boiling cooling device disclosed in this specification, the amount of the liquid-phase refrigerant in the gas-liquid separator can be appropriately controlled.

Drawing 1 is an explanatory view showing a schematic structure of a boiling cooling device of an embodiment. FIG. 2 is a flowchart showing an example of the control of the boiling cooling device of the embodiment. FIG. 3 is an example of a map showing the load of the internal combustion engine.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the dimensions, ratios, and the like of each part may not be shown so as to completely match the actual ones. In some cases, details are omitted in some drawings.

(Embodiment)
First, an internal combustion engine control apparatus according to an embodiment will be described with reference to FIG. Drawing 1 is an explanatory view showing a schematic structure of boiling cooling device 100 of an embodiment. The boiling cooling device 100 includes a refrigerant passage 12 formed inside the internal combustion engine 10. The refrigerant passage 12 is, for example, a water jacket formed around the cylinder of the internal combustion engine 10, but may take other forms as long as the internal combustion engine 10 can be cooled by the refrigerant in the refrigerant passage 12. The refrigerant flowing through the refrigerant passage 12 absorbs the heat of the internal combustion engine 10 and boils, whereby the internal combustion engine 10 is cooled. The refrigerant flowing in the refrigerant passage 12 is not particularly limited as long as it is a liquid that absorbs the heat of the internal combustion engine 10 and boils. In the present embodiment, a refrigerant in which water and ethylene glycol are mixed is used.

  The refrigerant passage 12 is provided with an outlet 12a in a cylinder head provided in the internal combustion engine 10, and a first steam passage 13 is connected to the outlet 12a. A first temperature sensor 13 a is provided in the first steam passage 13. The first temperature sensor 13 a measures the temperature of the refrigerant flowing through the first vapor passage 13. The other end of the first steam passage 13 is connected to a gas-liquid separator 14. The refrigerant flowing through the first vapor passage 13 is mainly a gas phase refrigerant vaporized in the refrigerant passage 12, but a liquid phase refrigerant may be mixed. The gas-liquid separator 14 includes a steam outlet 14a. A second steam passage 15 is connected to the steam outlet 14a. A turbine 17 that is an example of an expander is disposed at the other end of the second steam passage 15. A superheater 16 is provided in the second steam passage 15 between the gas-liquid separator 14 and the turbine 17. The superheater 16 supplies heat to the steam after passing through the gas-liquid separator 14 by being supplied with exhaust gas after passing through the exhaust heat steam generator 20 described later. The turbine 17 is driven by superheated steam that flows from the superheater 16. For example, a generator that generates power using the driving force of the turbine 17 is connected to the turbine 17. Thereby, the waste heat of the internal combustion engine 10 can be recovered. The driving force of the turbine 17 may be used as an auxiliary to the driving force of the internal combustion engine 10. Thus, the boiling cooling device 100 of this embodiment also functions as a Rankine cycle.

  As described above, the gas-liquid separator 14 disposed between the internal combustion engine 10 and the turbine 17 separates the refrigerant discharged from the internal combustion engine 10 into a liquid phase refrigerant and a gas phase refrigerant. The gas-liquid separator 14 stores the liquid phase refrigerant separated on the lower side. A first on-off valve 15 a is provided between the vapor outlet 14 a of the gas-liquid separator 14 and the superheater 16. The first on-off valve 15a is an electromagnetic valve and is electrically connected to the ECU 28 corresponding to the control unit. When the first on-off valve 15a is closed, the discharge of steam from the gas-liquid separator 14 is stopped. At the lower end of the gas-liquid separator 14, a first liquid phase refrigerant outlet 14b and a second liquid phase refrigerant outlet 14c are provided. A first liquid phase refrigerant passage 19 is connected to the first liquid phase refrigerant outlet 14b. The first liquid phase refrigerant passage 19 is provided with a first water pump (WP) 19a. The first water pump 19 a supplies liquid phase refrigerant to the refrigerant passage 12 formed in the internal combustion engine 10. A second liquid phase refrigerant passage 21 is connected to the second liquid phase refrigerant outlet 14c. The other end of the second liquid phase refrigerant passage 21 is connected to the exhaust heat steam generator 20, and supplies the liquid phase refrigerant to the exhaust heat steam generator 20. The gas-liquid separator 14 includes a liquid level sensor 14d that measures the internal liquid level, that is, the height of the stored liquid-phase refrigerant. The liquid level sensor 14d is electrically connected to the ECU 28.

  The gas-liquid separator 14 is provided with a discharge port 14e for discharging a liquid phase refrigerant. As will be described later, a refrigerant discharge passage 26 is connected to the discharge port 14e. The diameter of the discharge port 14e and the installation location thereof are provided corresponding to the liquid level height controlled using the liquid level sensor 14d. That is, the terms of the discharge port 14e are set so as to realize the liquid level height controlled using the liquid level sensor 14d, in other words, the upper limit liquid level and the lower limit liquid level. The height of the discharge port 14e is set to a height above the liquid level sensor 14d so that the liquid phase refrigerant does not flow into the turbine 17 that is an expander even when the liquid level is the same as the height of the discharge port 14e. ing. However, if the discharge port 14e is set at a position extremely higher than the desired liquid level, the liquid-phase refrigerant in the gas-liquid separator 14 cannot be discharged properly, and as a result, the gas-liquid separator 14 It will be necessary to set a large volume. On the contrary, if the discharge port 14e is set at a position very lower than the desired liquid level, the liquid phase refrigerant will be discharged too much, and the liquid phase refrigerant supplied to the internal combustion engine 10 will be insufficient. Insufficient cooling of the internal combustion engine 10 may occur. The terms of the outlet 14e are determined in consideration of at least these conditions.

  As described above, the boiling cooling device 100 of the present embodiment includes the exhaust heat steam generator 20. The exhaust heat steam generator 20 is provided around an exhaust pipe 18 connected to an exhaust manifold 10 a included in the internal combustion engine 10. The exhaust heat steam generator 20 uses the waste heat of the internal combustion engine 10 through the exhaust gas discharged through the exhaust pipe 18 to generate steam. Thereby, the waste heat of the internal combustion engine 10 is effectively used. The exhaust heat steam generator 20 is not essential for cooling the internal combustion engine 10, but by providing this, the efficiency of waste heat recovery can be improved as a whole apparatus.

  The exhaust heat steam generator 20 includes an outlet 20a. A second steam passage 22 is connected to the outlet 20a. A second temperature sensor 22 a is provided in the second steam passage 22. The second temperature sensor 22 a measures the temperature of the refrigerant flowing through the second vapor passage 22. The other end of the second steam passage 22 is connected to the gas-liquid separator 14. The refrigerant flowing through the second vapor passage 22 is mainly a gas phase refrigerant vaporized by the exhaust heat steam generator 20, but a liquid phase refrigerant may be mixed. Thus, the gas-liquid separator 14 separates not only the refrigerant boiled in the internal combustion engine 10 but also the refrigerant discharged from the exhaust heat steam generator 20 into a liquid-phase refrigerant and a gas-phase refrigerant.

  The boiling cooling device 100 includes a condenser 24 on the downstream side of the turbine 17 that cools the gas-phase refrigerant that has passed through the turbine 17 to form a liquid-phase refrigerant. The other end of the third steam passage 23 provided on the downstream side of the turbine 17 is connected to the condenser 24. The condenser 24 is a heat exchanger, exchanges heat with the refrigerant, cools the refrigerant, and returns the gas-phase refrigerant to the liquid-phase refrigerant. The third steam passage 23 is provided with a one-way valve 23 a so that steam does not flow backward from the condenser 24 side to the turbine 17 side.

  The boiling cooling device 100 includes a catch tank 25 that stores the liquid-phase refrigerant cooled by the condenser 24, that is, the refrigerant returned from the gas-phase refrigerant to the liquid-phase refrigerant. The catch tank 25 includes a refrigerant inlet 25a on the upper side and a refrigerant outlet 25b on the lower side. A refrigerant discharge passage 26 that discharges the liquid-phase refrigerant in the gas-liquid separator 14 to the catch tank 25 is connected to the refrigerant inlet 25a. That is, the refrigerant discharge passage 26 is connected to the discharge port 14 e provided in the gas-liquid separator 14. The refrigerant discharge passage 26 is provided with a second on-off valve 26a corresponding to a control valve. The second on-off valve 26 a is an electromagnetic valve and is electrically connected to the ECU 28. A refrigerant supply passage 27 that supplies the liquid-phase refrigerant in the catch tank 25 to the gas-liquid separator 14 is connected to the refrigerant outlet 25b. The refrigerant supply passage 27 is provided with a second water pump (WP) 27a. The second water pump 27a is an electric type, is electrically connected to the ECU 28, and is driven and controlled by the ECU 28 based on the measured value of the liquid level sensor 14d. A positive displacement pump is adopted as the second water pump 27a.

  An upper end side of the capacitor 24 is connected to a reserve tank 29 via a first connection pipe 30. The reserve tank 29 stores a liquid phase refrigerant. The lower end of the reserve tank 29 is connected to the catch tank 25 by a second connection pipe 31. The second connection pipe 31 is provided with a third on-off valve 31a. The third on-off valve 31a is an electromagnetic valve and is electrically connected to the ECU 28. When the third on-off valve 31a is opened, the liquid phase refrigerant in the reserve tank 29 can be replenished into the catch tank 25. That is, the liquid-phase refrigerant in the reserve tank 29 is replenished when the amount of refrigerant in the catch tank 25 and other locations connected to the catch tank 25 is insufficient. In the boiling cooling device 100 in a state where the boiling cooling is not performed, the liquid phase refrigerant may be circulated. When the liquid-phase refrigerant is circulated in this way, the capacitor 24 can function as a radiator. When the condenser 24 functions as a radiator, liquid phase refrigerant can be supplied from the reserve tank 29 to the condenser 24.

  The reserve tank 29 is connected to the negative pressure part 33 via the third connection pipe 32. Here, the negative pressure portion 33 in the present embodiment is a portion where negative pressure is generated in the intake system of the internal combustion engine 10. It should be noted that a portion that uses negative pressure, such as an exhaust pump, may be selected as the negative pressure portion 33 and the reserve tank 29 may be connected thereto. The third connection pipe 32 is provided with a fourth on-off valve 32a. The fourth on-off valve 32a is an electromagnetic valve and is electrically connected to the ECU 28. When the fourth on-off valve 32a is opened, the pressure in the region from the capacitor 24 to the catch tank 25 decreases. When the second on-off valve 26a is opened in this state, the liquid-phase refrigerant in the gas-liquid separator 14 is discharged to the catch tank 25 due to the difference between the pressure in the gas-liquid separator 14 and the pressure in the catch tank 25. The In the boiling cooling device 100 forming the Rankine cycle, the condenser 24 and the catch tank 25 located on the downstream side of the turbine 17 are in a low pressure state as compared with the upstream side, but are connected to the negative pressure portion 33. Thus, the capacitor 24 and the catch tank 25 can be brought into a lower pressure state.

  The boiling cooling device 100 includes an ECU 28 as a control unit. As described above, the ECU 28 is connected to various sensors, various on-off valves, and the like, and controls the operation of each unit. The control of the ECU 28 is executed by cooperation of hardware such as a CPU (Central Processing Unit) and software stored in a ROM (Read Only Memory) or the like. The ECU 28 includes a timer unit 28a. The timer unit 28a measures time in an example of control described later.

  Next, an example of control performed in the boiling cooling device 100 will be described with reference to FIGS. 2 and 3. FIG. 2 is a flowchart showing an example of control of the boiling cooling device 100 of the embodiment. FIG. 3 is an example of a map showing the load of the internal combustion engine.

  Control in the boiling cooling device 100 is started when the internal combustion engine 10 is started. When the internal combustion engine 10 is started, first, the fourth on-off valve 32a is opened (step S0). As a result, the pressure in the reserve tank 29, the condenser 24, and the catch tank 25 communicated with the negative pressure portion 33 is lowered. The fourth on-off valve 32a may be opened after the ignition is turned on, for example, after the internal combustion engine 10 is not completely started. Further, the temperature of each part of the internal combustion engine 10 is measured at the same time as this timing or at a timing slightly before and after. Following step S0 and in step S1 performed simultaneously with this, it is determined whether or not the internal combustion engine 10 is in a cold start state. In this embodiment, although it determines based on the measured value of the temperature sensor installed in the refrigerant path 12, you may determine using the measured value by the 1st temperature sensor 13a or the 2nd temperature sensor 22a. In short, any means may be adopted as long as the warm-up state of the internal combustion engine 10 can be determined. Whether or not the warm-up is completed is determined based on whether or not the refrigerant exceeds a predetermined threshold. When YES is determined in step S1, that is, when the internal combustion engine 10 is cold-started, in step S2, it is determined whether or not the measured value of the second temperature sensor 22a is equal to or less than a threshold value T1. If YES is determined in the step S2, the process proceeds to a step S3. In step S3, it is determined whether or not the measured value of the first temperature sensor 13a is equal to or less than a threshold value T1. If YES is determined in the step S3, the process proceeds to a step S4. In step S4, both the first on-off valve 15a and the second on-off valve 26a are closed. After performing the measure of step S4, the measure from step S2 is repeated again. This is to wait until the internal combustion engine 10 is completely warmed up and the liquid-phase refrigerant can be changed to the gas-phase refrigerant.

  On the other hand, if NO is determined in step S2 and NO is determined in step S3, the process proceeds to step S5. In step S5, the second on-off valve 26a is opened while maintaining the closed state of the first on-off valve 15a. Thereby, the catch tank 25 and the gas-liquid separator 14 which are in a low pressure state are brought into communication. As a result, the boiling of the liquid phase refrigerant in the refrigerant passage 12 connected to the gas-liquid separator 14 by the first vapor passage 13 and the exhaust heat steam generator 20 connected to the gas-liquid separator 14 and the second vapor passage 22. Is started. This is because the liquid-phase refrigerant in the internal combustion engine 10 and the exhaust heat steam generator 20 is likely to boil if the pressure of the refrigerant passage 12 and the exhaust heat steam generator 20 is lowered while the temperature is rising. Because. When the internal combustion engine 10 and the exhaust heat steam generator 20 are compared, the temperature of the exhaust heat steam generator 20 that is in contact with the high-temperature exhaust gas and has a small heat capacity tends to increase rapidly. For this reason, in this embodiment, the warm-up determination (step S2) based on the measurement value of the first temperature sensor 13a (step S3) is determined based on the measurement value of the second temperature sensor 22a on the exhaust heat steam generator 20 side. ) Precedes.

  In step S5, when the second on-off valve 26a is opened and boiling is started in the refrigerant passage 12 and the exhaust heat steam generator 20, the liquid-phase refrigerant pushed by the boiling passes through the discharge port 14e and the refrigerant discharge passage 26. Pushed out. The pushed liquid phase refrigerant is sent to the catch tank 25.

  In step S6 performed subsequent to step S5, it is determined whether or not the liquid level sensor 14d detects that the lower limit liquid level has been reached. If NO is determined in step S6, the process is repeated until YES is determined in step S6. That is. Monitor whether the lower liquid level has been reached.

  If YES is determined in the step S6, the process proceeds to a step S7. In step S7, the first on-off valve 15a is opened, and the second on-off valve 26a is closed. When the first on-off valve 15a is opened, the gas-liquid separator 14, the superheater 16, and the turbine 17 are in communication with each other, and the turbine 17 is driven by the gas-phase refrigerant, that is, steam. . At this time, the liquid level in the gas-liquid separator 14 is controlled to the lower limit liquid level. For this reason, it is suppressed that a liquid phase refrigerant flows out into the superheater 16 or the turbine 17 side. If the exhaust gas is introduced and the liquid refrigerant flows into the superheater 16 that is at a high temperature, the superheater 16 is rapidly cooled by the latent heat of vaporization, and a large temperature distribution occurs in the members constituting the superheater 16. The superheater 16 may be damaged due to thermal strain. If the inflow of the liquid refrigerant to the superheater 16 is avoided, such a situation is suppressed. Moreover, if the liquid phase refrigerant flows into the turbine 17, the liquid phase refrigerant may collide with the turbine rotating at high speed, and the output of the turbine 17 may be reduced or the blades may be damaged. If the inflow of the liquid refrigerant to the turbine 17 is avoided, such a situation is suppressed.

  In order to suppress the inflow of the liquid phase refrigerant to the superheater 16 and the turbine 17, it is assumed that the amount of the liquid phase refrigerant in advance after the cold start and before boiling occurs in the refrigerant passage 12 and the exhaust heat steam generator 20. It is conceivable to reduce the amount. However, if the amount of the liquid phase refrigerant is reduced in advance as described above, a part of the constituent walls of the refrigerant passage 12 and the exhaust heat steam generator 20 are exposed from the liquid phase refrigerant. As a result, temperature distribution occurs, and there is a possibility that each part is damaged due to thermal strain or the like. For this reason, the measure which reduces the quantity of a liquid phase refrigerant beforehand cannot be adopted. Therefore, by discharging the liquid phase refrigerant from the outlet 14e provided in the gas-liquid separator 14 at the timing when the boiling starts, the inflow of the liquid phase refrigerant to the superheater 16 and the turbine 17 or the shortage of the liquid phase refrigerant. The refrigerant passage 12 and the exhaust heat steam generator 20 can be prevented from being exposed.

  In step S7, the second on-off valve 26a is closed to prevent the vapor, which is a gas-phase refrigerant, from flowing out to the catch tank 25 side.

  Subsequent to step S7, in step S8, counting by the time measuring unit 28a is started, and in step S9, driving of the second water pump 27a is started. The timer unit 28a measures the drive time of the second water pump 27a. In step S10, which is performed subsequent to step S9, it is determined whether or not the upper limit liquid level is detected by the liquid level sensor 14d. If NO is determined in step S10, the processing from step S9 is repeated. That is, the driving of the second water pump 27a is continued. If YES is determined in the step S10, the process proceeds to a step S11. In step S11, the second water pump 27a is stopped and the counting by the time measuring unit 28a is stopped. Thus, the 2nd water pump 27a is driven in order to supplement the liquid phase refrigerant | coolant reduced by boiling. That is, the gas-liquid separator 14 communicates with the refrigerant passage 12 via the first liquid phase refrigerant passage 19 and communicates with the exhaust heat steam generator 20 via the second liquid phase refrigerant passage 21. Then, the liquid phase refrigerant is supplied to the refrigerant passage 12 and the exhaust heat steam generator 20. For this reason, the liquid phase refrigerant in the gas-liquid separator 14 decreases. This decrease can be compensated by driving the second water pump 27a.

  In step S12, it is determined whether the arrival time from the lower limit liquid level to the upper limit liquid level is shorter than the reference water supply time t1. The reference water supply time t1 is stored in the ECU 28 in advance. Here, the reference water supply time t1 is a time required when the second water pump 27a is driven to supply an amount of liquid phase refrigerant that reaches the upper limit liquid level from the lower limit liquid level. Accordingly, assuming that the change in the liquid level occurs only by the supply of the liquid phase refrigerant by the second water pump 27a, the liquid level reaches the upper limit liquid level from the lower limit liquid level when the reference water supply time t1 elapses. . Therefore, when the arrival time from the lower limit liquid level to the upper limit liquid level is shorter than the reference water supply time t1, there may be other causes for increasing the liquid phase refrigerant. Here, a possible cause of increasing the liquid phase refrigerant is an inflow of the liquid phase refrigerant from the refrigerant passage 12 or the exhaust heat steam generator 20. For example, although the temperature of the liquid-phase refrigerant is low and actually does not boil in the refrigerant passage 12 or the exhaust heat steam generator 20, the first on-off valve 15a is opened in step S7, and the gas-liquid separator 14 is opened. It is assumed that boiling starts when the internal pressure further decreases. Therefore, in this embodiment, when YES is determined in step S12, the second on-off valve 26a is opened together with the first on-off valve 15a in step S13. Thereby, the liquid phase refrigerant in the gas-liquid separator 14 can be discharged to the catch tank 25 side. When the second water pump 27a is not driven and the liquid-phase refrigerant in the gas-liquid separator 14 increases, it is determined that the same phenomenon has occurred and the second on-off valve 26a is opened. Measures can be taken.

  On the other hand, if NO is determined in step S12, the process of step S13 is skipped and the process proceeds to step S14.

  In step S14 performed subsequent to step S12 or step S13, it is determined again whether or not the lower limit liquid level is detected by the liquid level sensor 14d. When it is determined NO in step S14, the processing from step S11 is repeated. On the other hand, when YES is determined in the step S14, it is determined whether or not the ignition is turned off in a step S15. This is a measure for determining whether or not to end the series of controls. When it is determined YES in step S15, the series of steps is ended (END). On the other hand, when NO is determined in step S15, the processing from step S8 is repeated.

  In this way, by controlling the liquid level height of the liquid-phase refrigerant in the gas-liquid separator 14, the liquid level height is set within an appropriate range between the upper limit liquid level and the lower limit liquid level. Can do.

  Next, the case where NO is determined in step S1, that is, the case where the warm-up of the internal combustion engine 10 is completed will be described. If NO is determined in step S1, the process proceeds to step S16. The measures in steps S16 to S24 are interrupt control that is preferentially performed so that the amount of the liquid-phase refrigerant in the gas-liquid separator 14 is appropriately controlled regardless of the state of the internal combustion engine 10. It prescribes. In step S16, the first on-off valve 15a is opened, and the second on-off valve 26a is closed. That is, the internal combustion engine 10 has already been warmed up and is in a state in which the gas-phase refrigerant can be supplied to the turbine 17. Therefore, the first on-off valve 15 a is opened to supply steam to the turbine 17. At this time, the second on-off valve 26a is closed so that steam does not flow out to the catch tank 25 side.

  In step S17, which is performed subsequent to step S16, a change in the operating state of the internal combustion engine 10 is determined. Specifically, it is determined whether or not there has been a sudden change to a high load. Referring to FIG. 3, for example, a low load region and a high load region including an idling state are defined. When there is a change from the low load region to the high load region, the ECU 28 determines whether or not the change is shorter than a predetermined threshold value t2. If the change time is shorter than the threshold value t2, it is determined YES in step S17 because there is a sudden change to a high load. If YES is determined in the step S17, the process proceeds to a step S18. If NO is determined in step S17, the process proceeds to steps after step S8.

  In step S18, counting by the time measuring unit 28a is started, and at the same time or subsequently, the second water pump 27a is stopped (step S19). In step S20, it is determined whether or not the upper limit liquid level is detected by the liquid level sensor 14d. If YES is determined in step S20, the count is stopped in step S21. After stopping the counting in step S21, it is determined in step S22 whether or not the upper limit liquid level has been reached within the threshold value t3. Here, the threshold value t3 is a value determined in advance as a standard time from the liquid level height to the upper limit liquid level when the internal combustion engine 10 is in the low load region shown in FIG. If YES is determined in the step S22, the process proceeds to the steps after the step S8.

  If YES is determined in the step S22, the process proceeds to a step S23. In step S23, the second on-off valve 26a is opened together with the first on-off valve 15a. As in step S13, the liquid-phase refrigerant in the gas-liquid separator 14 can be discharged to the catch tank 25 side. In step S24 performed subsequent to step S3, it is determined whether or not the liquid level sensor 14d has detected the lower limit liquid level. When it is determined NO in step S24, the measures from step S23 are repeated. When it is determined YES in step S24, it can be considered that the phenomenon caused by the sudden change of the internal combustion engine 10 to the high load region has ended, and thereafter, the process proceeds to steps after step S8.

  Here, the reason why the liquid level in the gas-liquid separator 14 rises although the second water pump 27a is stopped will be described. Even after the internal combustion engine 10 is warmed up, if the internal combustion engine 10 is in an extremely low load state such as an idle state, the amount of generated steam is extremely reduced. For this reason, the pressure of the refrigerant passage 12 and the exhaust heat steam generator 20 decreases. As a result, the liquid phase refrigerant flows from the gas-liquid separator 14 to the refrigerant passage 12 and the exhaust heat steam generator 20, and the refrigerant passage 12 and the exhaust heat steam generator 20 are filled with the liquid phase refrigerant. On the other hand, the liquid phase refrigerant in the gas-liquid separator 14 that has sent the liquid phase refrigerant to the refrigerant passage 12 and the exhaust heat steam generator 20 decreases. As a result, the second water pump 27a is driven based on the detection value of the liquid level sensor 14d, and the liquid phase refrigerant in the catch tank 25 is supplied into the gas-liquid separator 14, so that the refrigerant passage 12 and the exhaust heat steam The amount of liquid refrigerant in the system including the generator 20 increases. When the internal combustion engine 10 suddenly becomes a high load state from such a state, the liquid phase refrigerant is also pushed into the gas-liquid separator 14 together with the generated steam, and as a result, the liquid phase refrigerant flows into the superheater 16 and the turbine 17. Is more likely to do. The liquid phase refrigerant gradually decreases due to evaporation, but it is difficult to rapidly reduce the liquid phase refrigerant in the gas-liquid separator 14. Therefore, the liquid-phase refrigerant in the gas-liquid separator 14 is discharged to the catch tank 25 by opening the second on-off valve 26a in step S23.

  When the internal combustion engine 10 is mounted on a vehicle, sudden changes in the load can occur frequently, but by interrupting the control from step S16 to step S24, the amount of liquid-phase refrigerant in the gas-liquid separator 14 can be reduced. It can be controlled appropriately.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited to these. Various modifications of these embodiments are within the scope of the present invention, and It is apparent from the above description that various other embodiments are possible within the scope.

10 Internal combustion engine 12 Refrigerant passage (water jacket)
13 First steam passage 14 Gas-liquid separator 14a Steam outlet 14b First liquid phase refrigerant outlet 14c Second liquid phase refrigerant outlet 14d Level sensor 14e Discharge port 15 Second steam passage 15a First on-off valve 16 Superheater 17 Turbine ( Inflator)
20 Exhaust Heat Steam Generator 24 Condenser 25 Catch Tank 27a Second Water Pump 28 ECU
28a Timekeeping section

Claims (2)

An internal combustion engine that is cooled by boiling the refrigerant flowing in the refrigerant passage formed therein;
A gas-liquid separator that is disposed between the internal combustion engine and the expander and separates the refrigerant discharged from the internal combustion engine into a liquid-phase refrigerant and a gas-phase refrigerant;
A liquid level sensor for measuring the liquid level in the gas-liquid separator;
A condenser that is disposed downstream of the expander and cools the gas-phase refrigerant that has passed through the expander to form a liquid-phase refrigerant;
A catch tank for storing the liquid-phase refrigerant cooled by the condenser;
A refrigerant discharge passage for discharging the liquid-phase refrigerant in the gas-liquid separator to the catch tank;
A control valve provided in the refrigerant discharge passage;
A control unit that performs opening / closing control of the control valve based on the measurement value of the liquid level sensor;
A refrigerant supply passage for supplying the liquid-phase refrigerant in the catch tank to the gas-liquid separator;
A water pump provided in the refrigerant supply passage and driven and controlled by the control unit based on a measurement value of the liquid level sensor;
The control unit opens the control valve when it is determined that the warm-up of the internal combustion engine is completed, and then the liquid level height is a lower limit liquid level based on the measurement value of the liquid level sensor. When the water pump is driven while the control valve is closed, the liquid level height reaches the upper limit liquid level based on the measured value of the liquid level sensor. A boiling cooling device that performs control to stop driving of the water pump when it is determined . The boiling cooling apparatus according to claim 1, wherein the catch tank is connected to a negative pressure system.

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