JP2009097387A - Waste heat recovery apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste heat recovery apparatus enabling stable start of an apparatus having a pump, an expander, and a generator directly connected. <P>SOLUTION: The waste heat recovery apparatus including a Rankine cycle 20 having the pump 21, the expander 23 and a rotary electrical machine 25 coaxially connected, is provided with an open close means 27 opening and closing a bypass channel 26, a temperature detection means 206, and a pressure difference detection means 207, 208. When the control means 30 starts the Rankine cycle 20, the control means 30 opens the open close means 27, and operates the rotary electric machine 25 as a generator at predetermined rotation speed. When temperature of gaseous working fluid provided by the temperature detection means 206 gets to predetermined temperature or higher, the control means 30 closes the open close means 27, and increase operation rotation speed of the rotary electrical machine 25 from the predetermined rotation speed before pressure difference provided by the pressure difference detection means 207, 208 reaches predetermined pressure difference. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a waste heat utilization device that recovers power by utilizing waste heat of an internal combustion engine for a vehicle, for example.

  As a conventional waste heat utilization device, for example, as shown in Patent Document 1, a device provided with a generator in a Rankine cycle is known. The Rankine cycle consists of a pump that circulates the internal heat medium, a heat exchanger that heats the heat medium, an expander that rotates by the expansion of the heated heat medium (turbine), and heat dissipation that cools the expanded heat medium. The heat exchanger for use is connected in a ring shape. Here, a pump and a generator are connected to and integrated with the main shaft of the expander.

The heating heat exchanger is supplied with heating liquid or gas (gas turbine, engine exhaust, etc.). The heat medium sent from the pump becomes superheated steam in the heating heat exchanger, flows into the expander, and adiabatically expands in the expander to generate a driving force in the expander. Then, the pump and the generator connected by this driving force are operated, the operation of the Rankine cycle is continued, and the exhaust heat energy is stored as electric energy. The expanded heat medium is cooled and condensed by cooling air or the like in a heat radiating heat exchanger and sucked into a pump.
JP 2004-108220 A

  However, in the technique described in the above cited reference 1, when a heat medium is flowed from the heat exchanger for heating into the expander at the start of the Rankine cycle, a rapid pressure difference is applied between the inlet and outlet of the expander, As a result, a large force acts on the sliding portion of the expander, and is affected by a decrease in durability. Therefore, there is a problem that it is difficult to start a stable Rankine cycle.

  In view of the above problems, an object of the present invention is to provide a waste heat utilization device that enables a stable start-up when a pump, an expander, and a generator are directly connected.

  In order to achieve the above object, the present invention employs the following technical means.

In the first aspect of the invention, the pump (21) for pumping the liquid phase working fluid, the liquid phase working fluid pumped from the pump (21) is heated by the waste heat of the heat generating device (10), Heater (22), an expander (23) that converts expansion energy of the gas-phase working fluid that flows out of the heater (22) into mechanical energy, and a gas phase after expansion that flows out of the expander (23) A Rankine cycle (20) comprising a condenser (24) that condenses and liquefies the working fluid and flows to the pump (21);
A rotating electrical machine (25) having both functions of an electric motor and a generator;
Control means (30) for controlling the operation of the rotating electrical machine (25),
In the waste heat utilization apparatus in which the pump (21), the expander (23), and the rotating electrical machine (25) are connected coaxially,
A bypass flow path (26) for bypassing the expander (23);
Opening and closing means (27) controlled by the control means (30) and opening and closing the bypass flow path (26);
Temperature detection means (206) for detecting the temperature of the gas phase working fluid on the inlet side of the expander (23);
Pressure difference detection means (207, 208) for detecting the pressure difference between the inlet and outlet of the expander (23),
When the control means (30) starts the Rankine cycle (20),
Opening and closing means (27) is opened and the rotating electrical machine (25) is operated as a motor at a predetermined rotational speed,
When the temperature of the gas-phase working fluid obtained by the temperature detection means (206) exceeds a predetermined temperature, the opening / closing means (27) is closed, and the pressure difference obtained by the pressure difference detection means (207, 208) becomes the predetermined pressure difference. In the meantime, the operating rotational speed of the rotating electrical machine (25) is increased with respect to a predetermined rotational speed.

  Thereby, the pump (21) and the expander (23) are first operated by opening the opening / closing means (27) and operating the rotating electrical machine (25) at a predetermined rotational speed as an electric motor. The working fluid flows mainly through the bypass channel (26) while flowing toward the expander (23). Therefore, the working fluid circulates through the Rankine cycle (20) without causing a pressure difference between the inlet and outlet of the expander (23).

  When the temperature of the working fluid on the inlet side of the expander (23) becomes equal to or higher than a predetermined temperature, the working fluid is sufficiently overheated and the expander (23) can be driven by the expansion of the working fluid. Can be confirmed.

  By closing the opening / closing means (27) at this stage, the working fluid can be caused to flow from the bypass channel (26) side to the expander (23) side, and the expander (23) is operated by the expansion of the working fluid. be able to.

  At this time, a pressure difference is generated between the inlet and outlet of the expander (23). By increasing the operating rotational speed of the rotating electrical machine (25) with respect to the predetermined rotational speed according to the pressure difference, the expander ( Since the discharge speed of the expander (23) can be increased sequentially by increasing the operating rotational speed of 23), the rise characteristic of the pressure difference (increase rate of the pressure difference with respect to time) can be moderated.

  Therefore, generation | occurrence | production of the rapid pressure difference in an expander (23) is suppressed, and starting of a stable Rankine cycle (20) is attained.

  The invention according to claim 2 is characterized in that the control means (30) continuously and monotonously increases the operating rotational speed of the rotating electrical machine (25) with respect to a predetermined rotational speed.

  Thereby, generation | occurrence | production of the abrupt pressure difference in an expander (23) can be suppressed reliably.

  The invention according to claim 3 is characterized in that the control means (30) increases the operating rotational speed of the rotating electrical machine (25) stepwise with respect to a predetermined rotational speed.

  Thus, similar to the second aspect, it is possible to reliably suppress the generation of a sudden pressure difference in the expander (23).

In invention of Claim 4, it is provided with the supercooling degree detection means (205) which detects the supercooling degree of the working fluid in the inlet side of a pump (21),
When the control means (30) operates the rotating electric machine (25) as an electric motor,
As the predetermined rotational speed, first, it is operated at the first predetermined rotational speed,
When the supercooling degree obtained by the supercooling degree detection means (205) is equal to or higher than the predetermined supercooling degree, the supercooling degree detecting means (205) is operated at a second predetermined rotational speed lower than the first predetermined rotational speed.

  Thus, first, when the pump (21) and the expander (23) are operated by the rotating electrical machine (25), the first predetermined rotation speed on the high rotation side that can be set as the predetermined rotation speed is set to the pump ( 21), the working fluid can be circulated in the Rankine cycle (20) in a short time. Therefore, with respect to the invention described in claim 1, it is possible to shorten the time until the opening / closing means (27) is closed, and to start the Rankine cycle (20) stably.

  When the degree of supercooling of the working fluid on the inlet side of the pump (21) becomes equal to or higher than the predetermined degree of supercooling, the working fluid is in a sufficiently supercooled state, and the pump (21) is sufficient without involving the gas phase working fluid. Therefore, it is possible to determine the appropriate switching timing from the first predetermined rotational speed to the second predetermined rotational speed.

  In the invention according to claim 5, the control means (30) continuously monotonously decreases from the first predetermined rotational speed to the second predetermined rotational speed when the rotating electrical machine (25) is operated at the second predetermined rotational speed. It is characterized in that it is reduced or stepped.

  Accordingly, the operating rotational speed of the rotating electrical machine (25) can be smoothly reduced from the first predetermined rotational speed to the second predetermined rotational speed, and the operation of the Rankine cycle (20) can be performed without difficulty.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment description later mentioned.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic diagram showing the entire system of a waste heat utilization apparatus 1 having a Rankine cycle 20. As shown in FIG. 1, the waste heat utilization apparatus 1 of this embodiment is applied to a vehicle using an engine 10 as a drive source.

  The engine (heat generating device) 10 is a water-cooled internal combustion engine, a radiator circuit 11 that cools the engine 10 by circulation of engine cooling water, and a heater circuit 12 that heats conditioned air by circulation of cooling water (hot water). Is provided.

  The radiator circuit 11 is provided with a radiator 13. The radiator 13 cools the cooling water circulated by the hot water pump 14 by exchanging heat with the outside air. The hot water pump 14 may be either an electric pump or a mechanical pump. In the radiator circuit 11, there is provided a radiator bypass passage 15 through which the cooling water flows around the radiator 13, and the cooling water amount that flows through the radiator 13 by the thermostat 16 and the cooling water amount that flows through the radiator bypass passage 15. And are to be adjusted.

  The heater circuit 12 is provided with a heater core 17, and cooling water (hot water) is circulated by the hot water pump 14. The heater core 17 is disposed in an air conditioning case of the air conditioning unit, and heats conditioned air blown by a blower (all not shown) by heat exchange with hot water. The heater core 17 is provided with an air mix door (not shown), and the amount of conditioned air flowing through the heater core 17 is varied by opening and closing the air mix door.

  The heater circuit 12 is formed with a heater flow path 18 that bypasses the heater core 17. The heater flow path 18 is provided with a heater 22 of a Rankine cycle 20 to be described later, and cooling water flows through the heater 22. A shut valve 19 is provided on the upstream side of the heater 22, and by opening / closing control of the shut valve 19, it is possible to appropriately adjust whether or not the coolant flows to the heater 22 side.

  On the other hand, the Rankine cycle 20 collects waste heat energy (heat of cooling water) generated in the engine 10 and uses the waste heat energy as mechanical energy (driving force of an expander 23 described later), and further, electric energy. This is used after being converted into (a power generation amount of a motor generator 25 described later). Hereinafter, the Rankine cycle 20 will be described.

  The Rankine cycle 20 includes a pump 21, a heater 22, an expander 23, and a condenser 24, which are connected in a ring shape to form a closed circuit. Further, a bypass passage 26 that bypasses the expander 23 is provided between the heater 22 and the condenser 24, and a bypass valve (opening / closing means) 27 is provided in the bypass passage 26. The bypass valve 27 can be formed, for example, as an electromagnetic valve, and the opening / closing operation of the valve body is controlled by an energization control circuit 30 described later.

  The pump 21 is an electric pump that circulates a liquid phase refrigerant (liquid phase working fluid) in the Rankine cycle 20 using a motor generator 25 or an expander 23 operated by an energization control circuit 30 described later as a drive source. . The pump 21 is connected by the same drive shaft as the motor generator 25 and the expander 23.

  The heater 22 heats the refrigerant by exchanging heat between the refrigerant pumped from the pump 21 and the high-temperature cooling water flowing through the heater flow path 18 to obtain superheated vapor refrigerant (gas phase working fluid). It is a heat exchanger.

  The expander 23 is a fluid device that generates a rotational driving force by the expansion of the superheated steam refrigerant heated by the heater 22. A motor generator 25 and a pump 21 are connected to the drive shaft of the expander 23. Then, the motor generator 25 and the pump 21 are operated by the driving force of the expander 23, and the electric power generated by the motor generator 25 is charged to the battery 33 via an inverter 31 that constitutes an energization control circuit 30 described later. It has become. The superheated vapor refrigerant flowing out from the expander 23 reaches the condenser 24.

  The condenser 24 is connected to the discharge side of the expander 23 and condenses and liquefies the superheated steam refrigerant after expansion by heat exchange with cooling air blown by an axial flow type so-called suction type blower fan 28. It is a heat exchanger used as a refrigerant. The liquid-phase refrigerant that flows out of the condenser 24 reaches the pump 21.

  The motor generator 25 is a rotating electric machine having both functions of an electric motor and a generator, and is controlled by an energization control circuit 30. A pump 21 is connected to a shaft on one end side of the motor generator 25, and an expander 23 is connected to a shaft on the other end side.

  The energization control circuit 30 is a control means for controlling the operation of various devices in the waste heat utilization apparatus 1, and includes an inverter 31 and a control device 32 (ECU). The inverter 31 controls the operation of the motor generator 25 connected to the pump 21 and the expander 23. The inverter 31 operates the motor generator 25 as an electric motor by supplying electric power from the battery 33 to the motor generator 25 to drive the pump 21 and the expander 23. Further, the inverter 31 charges the battery 33 with electric power generated when the motor generator 25 is operated as a generator by the driving force of the expander 23.

  Furthermore, the Rankine cycle 20 includes an expander temperature sensor (temperature detection means) 206 for detecting the inlet side refrigerant temperature of the expander 23, and an inlet side pressure sensor (for detecting the inlet side refrigerant pressure of the expander 23). Various sensors such as a pressure difference detecting means) 207 and an outlet side pressure sensor (pressure difference detecting means) 208 for detecting the outlet side refrigerant pressure of the expander 23 are disposed.

  Based on the detection signals from these various sensors 206, 207, 208, etc., the control device 32 controls the operation of the inverter 31, and also the shut valve 19, the blower fan 28, the motor generator 25 (the pump 22 and the expansion). Machine 23), bypass valve 27 and the like are controlled together.

  Next, the operation based on the above configuration and the operation and effect thereof will be described. FIG. 2 is a flowchart showing the control at the start of the Rankine cycle 20 according to the present embodiment. FIG. 3 is a time chart showing the expander differential pressure and the pump expander rotation speed from the start of the Rankine cycle 20 to the normal control. 4 is a schematic diagram showing the refrigerant flow rate in each part when the Rankine cycle 20 is started.

(1) Rankine start-up control The energization control circuit 30 opens the shut valve 19 and operates the blower fan 28 when starting the Rankine cycle 20. Then, as shown in FIG. 2, the bypass valve 27 is opened in step S100, and in step S110, the motor generator 25 is operated as a motor at a predetermined rotational speed (expander rotational speed predetermined value 1 in FIG. 3). Here, the predetermined rotational speed is a rotational speed that is predetermined as a minimum rotational speed (for example, 1500 rpm) that can be controlled by the inverter 31.

  By operating the motor generator 25, the pump 21 and the expander 23 are operated, and the refrigerant in the Rankine cycle 20 is circulated. At this time, since the bypass valve 27 is opened, the refrigerant mainly flows through the bypass flow channel 26 of the expander 23 and the bypass flow channel 26 ((a) of FIG. 4), and also to the expander 23. Will flow. Since the refrigerant mainly flows through the bypass flow path 26, a pressure difference between the inlet and outlet of the expander 23 (hereinafter referred to as expander differential pressure) does not occur (between MG activation and bypass valve closing in FIG. 3).

  Then, the refrigerant circulates in the Rankine cycle 20, so that the lubricating oil contained in the refrigerant is evenly distributed to the sliding portions of the pump 21 and the expander 23, and the pump 21 and the expander 23 are in a lubrication state.

  Next, in step S120, it is determined whether or not the expander inlet refrigerant temperature obtained from the expander temperature sensor 206 is equal to or higher than a predetermined temperature. If it is equal to or higher than the predetermined temperature, the bypass valve 27 is closed in step S130. If it is determined NO in step S120, step S110 is continued.

  The predetermined temperature here is a temperature set in advance as a refrigerant temperature (refrigerant superheat degree) at which the expander 23 can be sufficiently driven by the expansion of the superheated steam refrigerant flowing into the expander 23. The predetermined temperature can be determined, for example, as a value (60 to 70 ° C.) that is about 20 ° C. lower than the engine coolant temperature (80 to 90 ° C.).

  By closing the bypass valve 27, the refrigerant flow on the bypass flow path 26 side is blocked, and all the refrigerant in the Rankine cycle 20 flows on the expander 23 side ((b) of FIG. 4). At this time, the expander 23 becomes a resistance and an expander differential pressure is generated (between the closing of the bypass valve and the completion of the cycle start in FIG. 3). The energization control circuit 30 calculates the expander differential pressure as a difference between the inlet side refrigerant pressure obtained by the inlet side pressure sensor 207 and the outlet side refrigerant pressure obtained by the outlet side pressure sensor 208.

  The energization control circuit 30 increases the rotation speed of the motor generator 25 until the expander differential pressure reaches a predetermined differential pressure (predetermined pressure difference) by repeating Step S140 and Step S150. Here, the predetermined differential pressure is a differential pressure that is determined in advance from the relationship between the volume and pressure in the expander 23 so that an appropriate expansion operation is performed (no overexpansion operation or underexpansion operation is performed). Further, the rotational speed of the motor generator 25 is controlled so as to continuously increase monotonously (linear increase) (between the closing of the bypass valve and the completion of the cycle start in FIG. 3).

  If it is determined in step S150 that the expander differential pressure has reached a predetermined differential pressure, the routine proceeds to normal control of the motor generator 25 in step S160, and Rankine activation control is terminated.

(2) Rankine normal control After the Rankine start-up control, the energization control circuit 30 controls the rotation speed of the motor generator 25 and further the rotation speed of the blower fan 28 so that the expander differential pressure becomes a predetermined differential pressure. Thus, the waste heat energy of the engine 10 is converted into mechanical energy by the expander 23 and electric energy by the motor generator 25.

  That is, in Rankine normal control, the expander 23 is driven by the expansion of the superheated steam refrigerant from the heater 22. Then, the pump 21 is driven by the driving force of the expander 23, and the circulation of the refrigerant in the Rankine cycle 20 is continued.

  When the driving force of the expander 23 exceeds the driving force for driving the pump 21, the motor generator 25 is operated as a generator, and the control device 32 converts the electric power generated by the motor generator 25 into the inverter The battery 33 is charged via 31. The electric power charged in the battery 33 is supplied to various auxiliary machines of the vehicle.

(3) Rankine stop control When the amount of charge in the battery 33 exceeds a predetermined value, or when the waste heat of the engine 10 (the degree of superheat of the expander inlet refrigerant) is not sufficiently obtained, the energization control circuit 30 The operation of the Rankine cycle 20 is stopped. When stopping the Rankine cycle 20, the rotational speed of the motor generator 25 is reduced to the minimum rotational speed, the bypass valve 27 is opened, and it is confirmed that the expander differential pressure is sufficiently small. The pump 21 and the expander 23 are stopped by stopping the operation of 25. At the same time, the blower fan 28 is stopped.

  When any abnormality or the like occurs during the operation of the Rankine cycle 20, the energization control circuit 30 closes the shut valve 19 to prevent the engine cooling water from flowing into the heater 22 and forcibly rankin. The operation of cycle 20 is stopped.

  As described above, in the present embodiment, when the Rankine cycle 20 is started, the Rankine start-up control described in the above section (1) is performed. Therefore, first, the bypass valve 27 is opened to connect the motor generator 25 to the electric motor. As a result, the pump 21 and the expander 23 can be operated. At this time, since the refrigerant flows mainly through the bypass flow path 26 while flowing toward the expander 23, the refrigerant circulates through the Rankine cycle 20 without causing an expander differential pressure, and the refrigerant in the pump 21 and the expander 23. Lubricating oil contained in the refrigerant is supplied to each sliding portion. That is, at the initial startup stage, the pump 21 and the expander 23 can be prepared in a lubricated state.

  When the expander inlet refrigerant temperature (superheat degree) becomes equal to or higher than a predetermined temperature, the refrigerant is sufficiently superheated, and the expander 23 may be driven by expansion of the refrigerant (superheated vapor refrigerant). I can confirm.

  By closing the bypass valve 27 at this stage, the refrigerant can be caused to flow from the bypass flow path 26 side to the expander 23 side, and the expander 23 can be operated by expansion of the refrigerant.

  At this time, an expander differential pressure is generated. By increasing the operating rotational speed of the motor generator 25 relative to a predetermined rotational speed in accordance with the expander differential pressure, the operating rotational speed of the expander 23 is increased. Since the discharge capacity of the expander 23 can be increased sequentially, the rising characteristic of the expander differential pressure (increase rate of the pressure difference with respect to time) can be moderated. That is, as shown in FIG. 4 (c), for example, if the pump 21 is discharging a refrigerant having a flow rate of 3 at a predetermined rotation speed (for example, 1500 rpm), the rotation speed of the motor generator 25 is increased (for example, 1500 rpm → 2000 rpm), when the refrigerant flows into the expander 23, the rotational speed of the expander 23 has already been increased (2000 rpm), and the expansion operation is performed so that the refrigerant with the flow rate 4 can be discharged with respect to the refrigerant with the flow rate 3; Since this relationship is repeated, the degree of increase in the expander differential pressure can be moderated.

  Therefore, generation | occurrence | production of rapid expander differential pressure | voltage is suppressed and starting of the stable Rankine cycle 20 is attained.

(Modification of the first embodiment)
In the first embodiment, the rotational speed of the motor generator 25 (the rotational speed of the pump 21 and the expander 23) is controlled so as to continuously increase monotonously (linear increase) as the expander differential pressure increases. However, as shown in FIG. 5A, the rate of increase may be controlled so as to decrease with time.

  Further, as shown in FIG. 5B, the rotation speed of the motor generator 25 (the rotation speed of the pump 21 and the expander 23) may be controlled to increase stepwise.

(Second Embodiment)
A second embodiment of the present invention is shown in FIGS. The waste heat utilization apparatus 1A of the second embodiment adds a pump temperature sensor 205 to the first embodiment, and performs two-stage rotation speed control when the motor generator 25 is first operated in Rankine start-up control. This is done separately.

  As shown in FIG. 6, the inlet side refrigerant for obtaining the inlet refrigerant subcooling degree (subcool) of the pump 21 is provided on the inlet side (between the condenser 24 and the pump 21) of the pump 21 of the waste heat utilization apparatus 1 </ b> A. A pump temperature sensor (supercooling degree detection means) 205 for detecting the temperature is provided. A detection signal from the pump temperature sensor 205 is output to the controller 32.

  As shown in FIG. 7, Rankine start-up control of the second embodiment is obtained by changing step S110 to steps S101, S102, and S111 with respect to the first embodiment.

  That is, in the Rankine start-up control, the energization control circuit 30 opens the bypass valve 27 in step S100, and then operates the motor generator 25 at the first predetermined rotation speed in step S101 as the predetermined rotation speed. The first predetermined rotational speed is a rotational speed set as a rotational speed on the relatively high rotational speed side that can be controlled by the inverter 31 (between MG activation and completion of securing the refrigerant circulation amount in FIG. 8).

  When the motor generator 25 is operated at the first predetermined rotation speed, the pump 21 is operated on the high rotation side, and the refrigerant in the Rankine cycle 20 is circulated at a higher flow rate than in the case of the first embodiment.

  Then, in step S102, it is determined whether or not the inlet side refrigerant temperature (inlet refrigerant subcooling degree) obtained from the pump temperature sensor 205 is equal to or higher than a predetermined supercooling degree. Thus, the motor generator 25 is operated by switching the rotational speed of the motor generator 25 to a second predetermined rotational speed lower than the first predetermined rotational speed. The predetermined degree of supercooling here is a degree of supercooling determined in advance as a refrigerant temperature at which the refrigerant flowing out of the condenser 24 can surely become a liquid phase refrigerant. Further, the second predetermined rotational speed is predetermined as the minimum rotational speed (between the refrigerant circulation amount securing completion and the bypass valve closing in FIG. 8) that can be controlled by the inverter 31 as in the first embodiment. The number of revolutions. If it is determined NO in step S102, step S101 is continued.

  Then, in step S120, it is determined whether or not the expander inlet refrigerant temperature obtained from the expander temperature sensor 206 is equal to or higher than a predetermined temperature. If it is equal to or higher than the predetermined temperature, steps S130 to step are performed as in the first embodiment. If S160 is executed and it is determined as NO, Step S110 is continued.

  In the second embodiment, since the predetermined rotation speed when the first motor generator 25 is operated is the first predetermined rotation speed on the high rotation side, the discharge amount of the pump 21 is increased, and the refrigerant can be Rankine in a short time. It can be circulated in the cycle 20. Therefore, the time until the bypass valve 27 is closed can be shortened with respect to the first embodiment, and the Rankine cycle 20 can be stably started.

  When the degree of supercooling of the refrigerant on the inlet side of the pump 21 is equal to or higher than the predetermined degree of supercooling, the refrigerant is in a sufficiently subcooled state, and the refrigerant can be sufficiently circulated by the pump 21 without involving the gas phase refrigerant. Since it can be confirmed that it is in the state, it is possible to determine an appropriate switching timing from the first predetermined rotation speed to the second predetermined rotation speed.

(Modification of the second embodiment)
In the second embodiment, in the first operation of the motor generator 25, the refrigerant supercooling degree is equal to or higher than the predetermined supercooling degree, and the rotational speed is simply switched from the first predetermined rotational speed to the second predetermined rotational speed. As shown in FIG. 9, it may be continuously monotonously decreased. Or you may make it reduce in steps (illustration omitted). Thereby, the operation | movement of the smooth Rankine cycle 20 without an unreasonableness is attained.

(Other embodiments)
In each of the above embodiments, the expander differential pressure in the expander 23 is obtained from the inlet side pressure sensor 207 and the outlet side pressure sensor 208. However, the present invention is not limited to this, and the expander differential pressure is determined from the refrigerant temperature correlated with the refrigerant pressure. May be calculated.

  Moreover, in the said embodiment, although it was set as the vehicle engine 10 (engine cooling water) as a heat_generation | fever apparatus with waste heat, it is not restricted to this, For example, an external combustion engine, the fuel cell stack of a fuel cell vehicle, various Any device that generates heat during operation and discards a part of the heat for temperature control (waste heat is generated) such as a motor or an inverter can be widely applied.

  Moreover, although this waste heat utilization apparatus 1 (1A) was demonstrated as what is applied for vehicles, it is good not only for this but for stationary.

It is a schematic diagram which shows the whole system of the waste-heat utilization apparatus which has a Rankine cycle of 1st Embodiment. It is a flowchart which shows the control at the time of starting of the Rankine cycle of 1st Embodiment. It is a time chart which shows the expander differential pressure and pump expander rotation speed which are reached from the starting time of Rankine cycle of 1st Embodiment to normal control. It is a schematic diagram which shows the refrigerant | coolant flow rate in each site | part at the time of starting of the Rankine cycle of 1st Embodiment. It is a time chart which shows the expander differential pressure and pump expansion machine rotation speed which are reached from the time of starting of a Rankine cycle in the modification of 1st Embodiment to normal control. It is a schematic diagram which shows the whole system of the waste-heat utilization apparatus which has a Rankine cycle of 2nd Embodiment. It is a flowchart which shows the control at the time of starting of the Rankine cycle of 2nd Embodiment. It is a time chart which shows the expander differential pressure and pump expander rotation speed which are reached from the starting time of Rankine cycle of 2nd Embodiment to normal control. It is a time chart which shows the expansion machine differential pressure and pump expansion machine rotation speed which are reached from the time of starting of a Rankine cycle in the modification of 2nd Embodiment to normal control.

Explanation of symbols

1, 1A Waste heat utilization device 10 Engine (heat generation equipment)
20 Rankine Cycle 21 Pump 22 Heater 23 Expander 24 Condenser 25 Motor Generator (Rotating Electric Machine)
26 Bypass flow path 27 Bypass valve (opening / closing means)
30 Energization control circuit (control means)
205 Pump temperature sensor (supercooling degree detection means)
206 Expander temperature sensor (temperature detection means)
207 Inlet side pressure sensor (pressure difference detection means)
208 Outlet side pressure sensor (pressure difference detection means)

Claims (5)

A pump (21) for pumping a liquid phase working fluid, a heater (22) for heating the liquid phase working fluid pumped from the pump (21) by waste heat of the heat generating device (10) to form a gas phase working fluid, An expander (23) that converts expansion energy of the gas-phase working fluid that flows out of the heater (22) into mechanical energy, and condenses the expanded gas-phase working fluid that flows out of the expander (23) A Rankine cycle (20) comprising a condenser (24) that liquefies and flows out to the pump (21);
A rotating electrical machine (25) having both functions of an electric motor and a generator;
Control means (30) for controlling the operation of the rotating electrical machine (25),
In the waste heat utilization apparatus in which the pump (21), the expander (23), and the rotating electrical machine (25) are connected coaxially,
A bypass flow path (26) for bypassing the expander (23);
Opening and closing means (27) controlled by the control means (30) to open and close the bypass flow path (26);
Temperature detecting means (206) for detecting the temperature of the gas-phase working fluid on the inlet side of the expander (23);
Pressure difference detecting means (207, 208) for detecting a pressure difference between the inlet and outlet of the expander (23);
When the control means (30) starts the Rankine cycle (20),
Opening the opening / closing means (27) and operating the rotating electrical machine (25) as a motor at a predetermined rotational speed,
When the temperature of the gas-phase working fluid obtained by the temperature detecting means (206) becomes equal to or higher than a predetermined temperature, the opening / closing means (27) is closed and the pressure difference obtained by the pressure difference detecting means (207, 208) is increased. A waste heat utilization apparatus, wherein the operating rotational speed of the rotating electrical machine (25) is increased with respect to the predetermined rotational speed before reaching a predetermined pressure difference.   The waste heat utilization apparatus according to claim 1, wherein the control means (30) continuously and monotonically increases the operating rotational speed of the rotating electrical machine (25) with respect to the predetermined rotational speed.   The waste heat utilization apparatus according to claim 1, wherein the control means (30) increases the operating rotational speed of the rotating electrical machine (25) stepwise with respect to the predetermined rotational speed. Supercooling degree detection means (205) for detecting the degree of supercooling of the working fluid on the inlet side of the pump (21),
The control means (30), when operating the rotating electrical machine (25) as an electric motor,
As the predetermined rotational speed, first, it is operated at a first predetermined rotational speed,
The operation is performed at a second predetermined rotational speed lower than the first predetermined rotational speed when the supercooling degree obtained by the supercooling degree detection means (205) is equal to or higher than a predetermined supercooling degree. The waste heat utilization apparatus according to any one of claims 3 to 4.   The control means (30) continuously monotonously decreases from the first predetermined rotation speed to the second predetermined rotation speed when the rotating electrical machine (25) is operated at the second predetermined rotation speed, or in steps. The waste heat utilization apparatus according to claim 4, wherein the waste heat utilization apparatus is reduced to a shape.

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