JP6860351B2 - Rankine cycle controller - Google Patents

Description

The present invention relates to a Rankine cycle controller.

Conventionally, the Rankine cycle that uses heat to generate mechanical energy is known. For example, the Rankine cycle applied to a vehicle uses the waste heat of the engine generated in the vehicle to generate mechanical energy. Specifically, the Rankine cycle includes a flow path in which a heated working medium circulates, a pump provided in the flow path for circulating the working medium, and a flow path provided in the flow path to expand the working medium to generate rotational energy. Including an inflator to produce. Further, by connecting a generator to the inflator, it is possible to generate electricity using the rotational energy generated by the inflator. As a result, thermoelectric power generation, which is power generation using heat, is realized. In such a field related to thermoelectric power generation, a technique for connecting a generator to both a pump and an expander has been proposed in order to reduce the size of the device.

For example, Patent Document 1 describes a heat exchanger that heats a working fluid by waste heat of a vehicle in order to provide a compact and cost-reduced vehicle waste heat recovery system without lowering the waste heat recovery efficiency. A Rankin cycle having an expander that expands the working fluid heated by the heat exchanger, a capacitor that cools the working fluid expanded by the expander, and a pump that circulates the working fluid cooled by the condenser, and the said. Disclosed in a vehicle waste heat recovery system including a pump and a load machine connected to the expander, a technique in which the load machine drives the pump as a motor and generates power by using the power of the expander as a generator. Has been done.

Japanese Unexamined Patent Publication No. 2006-242174

By connecting the generator to both the pump and the expander in this way, the device can be miniaturized as compared with the case where the pump is driven by a dedicated electric motor. However, in the field of thermoelectric generation, it is considered desirable to miniaturize the device more effectively.

Specifically, when the generator is connected to both the pump and the inflator, the rotating shafts of the pump and the inflator may be configured to rotate integrally. In such a case, since it is difficult to adjust the difference in the rotational speeds of the pump and the inflator, the flow rate of the working medium discharged from each of the pump and the inflator to the downstream side (hereinafter, also referred to as a discharge flow rate). The difference between the two can be difficult to adjust. As a result, the volume of the working medium of the gas phase supplied to the expander (hereinafter, also referred to as steam volume flow rate) is the temperature of the working medium of the gas phase supplied to the inflator (hereinafter, also referred to as steam temperature). It can be almost constant regardless. In other words, the steam volume flow rate corresponds to the volume of the working medium of the gas phase passing through the expander per unit time.

When the steam volume flow rate is substantially constant, according to the ideal gas law, the pressure of the working medium of the gas phase supplied to the expander (hereinafter, also referred to as vapor pressure) has a correlation with the vapor temperature. Therefore, as the steam temperature rises, the vapor pressure may become excessively high, which may damage the expander. On the other hand, as the steam temperature decreases, the vapor pressure can become excessively low, so that the amount of power generation can decrease as the rotational energy generated by the expander decreases. Therefore, it may be necessary to adjust the vapor pressure appropriately according to the steam temperature.

Here, when the generator is connected to both the pump and the inflator, the difference in the discharge flow rate between the pump and the inflator is set to the steam temperature by providing a mechanism for adjusting the discharge amount per rotation of the pump or the inflator. It is conceivable to make it adjustable according to. Thereby, it is expected that the vapor pressure can be appropriately adjusted according to the steam temperature. However, since such a mechanism has a relatively large number of parts, it may be difficult to miniaturize the device more effectively.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a new and improved Rankine cycle control device capable of more effectively miniaturizing the device. Is to provide.

In order to solve the above problems, according to a certain viewpoint of the present invention, in the working medium flow path, which is a flow path through which the heated working medium circulates, and in the working medium flow path provided in the working medium flow path. In a Rankine cycle control device comprising a pump that circulates the working medium and an inflator that is provided in the working medium flow path to expand the working medium to generate rotational energy, the pump and the inflator are Each of them is connected to a motor generator, and in the Rankine cycle, a bypass flow path that communicates with the downstream side and the upstream side of the pump in the working medium flow path and the inside of the bypass flow path from the pump in the working medium flow path. A flow rate adjusting mechanism capable of adjusting the recirculation amount, which is the flow rate of the working medium that recirculates from the downstream side to the upstream side, is provided, and the control device transfers the recirculation amount adjusted by the flow rate adjusting mechanism to the inflator. It is controlled according to the steam temperature which is the temperature of the working medium of the supplied gas phase, and when the steam temperature is higher than the boiling point of the working medium at a predetermined pressure, the recirculation amount is increased as the steam temperature becomes higher. A Rankine cycle controller is provided that increases the discharge rate of the inflator relative to the flow rate sent from the pump to the inflator.

The control device, when the steam temperature is below the boiling point of the working medium in the predetermined pressure, as the steam temperature is lowered, by Rukoto increase the recirculation amount, feed from the pump to the expander The discharge amount of the inflator may be relatively large with respect to the flow rate to be obtained.

The working medium flow path is provided with a condenser that condenses the working medium of the gas phase that has passed through the expander, and the bypass flow path operates on the upstream side of the pump in the working medium flow path. It may be connected to the downstream side of the condenser in the medium flow path.

The working medium flow path is provided with a tank in which the working medium sucked up by the pump is stored, and the bypass flow path is located upstream of the pump in the working medium flow path and in the working medium flow path. It may be connected to the downstream side of the tank.

The flow rate adjusting mechanism may include an orifice provided in the bypass flow path and capable of adjusting the flow rate amount by adjusting the flow path area of the bypass flow path.

As described above, according to the present invention, the device can be miniaturized more effectively.

It is a schematic diagram which shows an example of the schematic structure of the charging system of the vehicle which concerns on embodiment of this invention. It is explanatory drawing which shows an example of the vapor pressure curve of a working medium. It is explanatory drawing for demonstrating an example of the relationship between a steam temperature and a target vapor pressure. It is explanatory drawing which shows an example of the map which shows the relationship between the steam temperature and the flow path area of a bypass flow path. It is explanatory drawing for demonstrating an example of the relationship between the steam temperature and the recirculation amount of a working medium.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

<1. Charging system configuration>
First, with reference to FIG. 1, a schematic configuration of a vehicle charging system 10 according to an embodiment of the present invention will be described. FIG. 1 is a schematic view showing an example of a schematic configuration of the charging system 10 according to the present embodiment. The charging system 10, for example, includes an engine 11, a driving force transmission system 51, a driving wheel 21, a high-voltage battery 31, and a traveling motor generator (traveling M / G) 41, as shown in FIG. , A pump motor generator (pump M / G) 61, a Rankine cycle 70, and a control device 100.

The engine 11 starts or stops according to the running state of the vehicle. For example, the engine 11 starts or stops according to a required torque while the vehicle is running. The driving force generated by the operation of the engine 11 is transmitted to the driving wheels 21 via the driving force transmission system 51. The cylinder block and cylinder head of the engine 11 are provided with a cooling water flow path 13 for circulating cooling water to cool the engine 11. The waste heat of the engine 11 is recovered by the cooling water circulating in the cooling water flow path 13. The cooling water flow path 13 is connected to the heat exchanger 74 of the Rankine cycle 70 outside the engine 11, and exchanges heat with the operating medium of the Rankine cycle 70 in the heat exchanger 74.

The high voltage battery 31 is a high voltage (for example, 200V) power supply source. Specifically, the high-voltage battery 31 supplies electric power to the pump motor generator 61 and the traveling motor generator 41, respectively, and also supplies electric power to the low-voltage battery that supplies electric power to various devices in the vehicle. The high-voltage battery 31 stores the electric power generated by the pump motor generator 61 and the electric power generated by the traveling motor generator 41, respectively.

The traveling motor generator 41 has a function as a driving motor that generates a driving force for the vehicle. Further, the traveling motor generator 41 has a function as a braking power generation generator that generates electricity by using the kinetic energy of the vehicle when the vehicle is decelerated and stores the generated electric power in the high voltage battery 31. The traveling motor generator 41 includes, for example, a three-phase AC motor and an inverter device, and is electrically connected to the high-voltage battery 31 via the inverter device. The inverter device also has a function as a converter device.

When the traveling motor generator 41 functions as a driving motor, DC power is supplied from the high-voltage battery 31 to the traveling motor generator 41. In the traveling motor generator 41, the DC power is converted into AC power by the inverter device and supplied to the motor. As a result, the driving force is generated by the motor of the traveling motor generator 41. The driving force generated by the traveling motor generator 41 is transmitted to the driving wheels 21 via the driving force transmission system 51. The control device 100 controls the generation of the driving force by the traveling motor generator 41 by controlling the inverter device of the traveling motor generator 41.

When the traveling motor generator 41 functions as a braking power generator when the vehicle is decelerated, the control device 100 controls the inverter device of the traveling motor generator 41, so that the motor uses the rotational energy of the drive wheels 21. Power is generated. The generated AC power is converted into DC power by the inverter device and stored in the high-voltage battery 31. As a result, resistance is given to the rotation of the drive wheels 21, and braking force is generated. The control device 100 controls the power generation by the traveling motor generator 41 by controlling the inverter device of the traveling motor generator 41. Specifically, the control device 100 controls the output voltage of the traveling motor generator 41 via the inverter device.

The Rankine cycle 70 uses the waste heat of the vehicle engine 11 to generate mechanical energy. The Rankine cycle 70 includes, for example, as shown in FIG. 1, a working medium flow rate 71, a pump 73, a heat exchanger 74, an expander 75, a condenser 77, a tank 79, and a bypass flow rate 76. And the flow rate adjusting mechanism 72.

The working medium flow path 71 is a flow path through which the heated working medium circulates. As the working medium, for example, water, chlorofluorocarbons, or alcohol can be applied. A pump 73, a heat exchanger 74, an expander 75, a condenser 77, and a tank 79 are provided in this order in the working medium flow path 71.

The pump 73 circulates the working medium in the working medium flow path 71. Specifically, the working medium sucked up by the pump 73 is stored in the tank 79, and the pump 73 sucks up the working medium stored in the tank 79. As a result, the working medium circulates in the working medium flow path 71. The pump 73 is connected to the pump motor generator 61. For example, the pump motor generator 61 includes a three-phase AC motor and an inverter device, and the rotating shaft of the pump 73 is connected to the rotor of the motor. Further, the pump 73 is driven by a pump motor generator 61. Specifically, a driving force is generated by the pump motor generator 61 based on an operation instruction from the control device 100, and the driving force is output to the rotation shaft of the pump 73 to control the driving of the pump 73. Is configured to.

The working medium flow path 71 and the cooling water flow path 13 are connected to the heat exchanger 74. In the heat exchanger 74, heat exchange is performed between the working medium and the cooling water. As a result, the working medium is heated and vaporized by the cooling water having the waste heat of the engine 11. As described above, the operating medium of the Rankine cycle 70 may be heated by, for example, the waste heat of the engine 11 of the vehicle.

The inflator 75 expands the working medium to generate rotational energy. Specifically, the expander 75 expands the working medium vaporized by the heat exchanger 74 to generate rotational energy. For example, in the expander 75, the working medium is sucked into the expansion chamber, the working medium expands in the expansion chamber, and the impeller receives the flow of the working medium, so that the rotary motion of the rotating shaft connected to the impeller is moved. Energy is generated. The inflator 75 is connected to the pump motor generator 61. Specifically, the rotating shaft of the expander 75 is connected to the rotor of the motor of the pump motor generator 61. Therefore, the rotational energy generated by the inflator 75 is transmitted to the pump motor generator 61 via the rotation shaft of the inflator 75.

The condenser 77 condenses the working medium of the gas phase that has passed through the expander 75. Specifically, the condenser 77 cools the working medium by releasing the heat of the working medium to the outside of the working medium flow path 71. As a result, the working medium of the gas phase is condensed. The working medium condensed by the condenser 77 is stored in the tank 79. The working medium stored in the tank 79 is sucked up again by the pump 73. In this way, the working medium circulates in the Rankine cycle 70 by sequentially flowing through the pump 73, the heat exchanger 74, the expander 75, the condenser 77, and the tank 79.

The pump motor generator 61 corresponds to the motor generator according to the present invention, which is connected to the pump 73 and the inflator 75, respectively. The pump motor generator 61 can output a driving force for driving the pump 73. Further, the pump motor generator 61 can generate electricity by using the rotational energy generated by the inflator 75. As described above, the pump motor generator 61 includes, for example, a three-phase AC motor and an inverter device, and is electrically connected to the high-voltage battery 31 via the inverter device. The inverter device also has a function as a converter device.

When the pump motor generator 61 functions as a drive motor that outputs a driving force for driving the pump 73, DC power is supplied from the high voltage battery 31 to the pump motor generator 61. In the pump motor generator 61, the DC power is converted into AC power by the inverter device and supplied to the motor. As a result, the driving force is generated by the motor of the pump motor generator 61. The driving force generated by the pump motor generator 61 is output to the rotating shaft of the pump 73. Thereby, the pump 73 is driven. The driving force generated by the pump motor generator 61 can also be output to the rotating shaft of the inflator 75. The control device 100 controls the generation of the driving force by the pump motor generator 61 by controlling the inverter device of the pump motor generator 61.

When the pump motor generator 61 functions as a thermal power generator that generates electricity using the rotational energy generated by the expander 75, the control device 100 controls the inverter device of the pump motor generator 61 to generate electricity. Is done. The generated AC power is converted into DC power by the inverter device and stored in the high-voltage battery 31. The control device 100 controls the power generation by the pump motor generator 61 by controlling the inverter device of the pump motor generator 61. Specifically, the control device 100 controls the output voltage of the pump motor generator 61 via the inverter device.

The bypass flow path 76 communicates with the downstream side and the upstream side of the pump 73 in the working medium flow path 71. For example, as shown in FIG. 1, one end of the bypass flow path 76 is connected to a portion between the pump 73 and the heat exchanger 74 in the working medium flow path 71, and the other end is a tank in the working medium flow path 71. It is connected to the portion between 79 and the pump 73. The working medium discharged by the pump 73 has a higher pressure than the working medium sucked by the pump 73. Therefore, a part of the working medium discharged by the pump 73 can return in the bypass flow path 76 from one end side to the other end side. In other words, a part of the working medium discharged by the pump 73 may return in the bypass flow path 76 from the downstream side to the upstream side of the pump 73 in the working medium flow path 71.

As described above, the bypass flow path 76 may be connected to the upstream side of the pump 73 in the working medium flow path 71 and to the downstream side of the condenser 77 in the working medium flow path 71. In other words, the other end of the bypass flow path 76 may be connected to the portion between the condenser 77 and the pump 73. Thereby, it is possible to prevent an increase in pressure loss due to the working medium refluxed through the bypass flow path 76 passing through the condenser 77 again. Therefore, it is possible to suppress a decrease in fuel consumption.

Further, as described above, the bypass flow path 76 may be connected to the upstream side of the pump 73 in the working medium flow path 71 and to the downstream side of the tank 79 in the working medium flow path 71. In other words, the other end of the bypass flow path 76 may be connected to a portion between the tank 79 and the pump 73. Thereby, it is possible to prevent an increase in energy loss due to the working medium recirculated through the bypass flow path 76 being sucked up from the tank 79 by the pump 73 again. Therefore, the decrease in fuel consumption can be suppressed more effectively.

The flow rate adjusting mechanism 72 can adjust the flow rate of the working medium flowing in the bypass flow path 76. Specifically, the flow rate adjusting mechanism 72 can adjust the amount of recirculation, which is the flow rate of the working medium that recirculates in the bypass flow path 76 from the downstream side to the upstream side of the pump 73 in the working medium flow path 71. The operation of the flow rate adjusting mechanism 72 is controlled by the control device 100. As a result, the amount of recirculation of the working medium adjusted by the flow rate adjusting mechanism 72 is controlled. Therefore, the flow rate sent to the inflator 75 out of the discharge flow rate of the pump 73 is controlled.

Specifically, the flow rate adjusting mechanism 72 includes an orifice provided in the bypass flow path 76 and capable of adjusting the return amount of the working medium by adjusting the flow path area of the bypass flow path 76. The adjustment of the flow path area of the bypass flow path 76 by the orifice can be realized by, for example, an electromagnetic valve whose opening degree can be adjusted based on an operation instruction from the control device 100. As the flow path area of the bypass flow path 76 increases, the amount of return of the working medium that returns in the bypass flow path 76 increases. Therefore, as the flow path area of the bypass flow path 76 increases, the flow rate sent to the expander 75 out of the discharge flow rate of the pump 73 decreases. When the flow path area of the bypass flow path 76 is 0, the working medium discharged from the pump 73 is sent to the expander 75 without refluxing in the bypass flow path 76. As described above, specifically, the control device 100 can control the amount of recirculation of the working medium by controlling the flow path area of the bypass flow path 76 by outputting an operation instruction to the flow rate adjusting mechanism 72. .. The flow rate adjusting mechanism 72 is not limited to such an example as long as the amount of recirculation in the bypass flow path 76 can be adjusted.

Various sensors may be provided in the charging system 10. For example, as shown in FIG. 1, the charging system 10 may be provided with a pump rotation speed sensor 201, a steam temperature sensor 205, and a water temperature sensor 207.

The pump rotation speed sensor 201 detects the rotation speed of the pump 73 and outputs the detection result. The pump rotation speed sensor 201 is provided, for example, in the vicinity of the rotation axis of the pump 73.

The steam temperature sensor 205 detects the steam temperature, which is the temperature of the working medium supplied to the expander 75, and outputs the detection result. The steam temperature sensor 205 is provided, for example, on the upstream side of the expander 75 in the working medium flow path 71 of the Rankine cycle 70.

The water temperature sensor 207 detects the temperature of the cooling water of the engine 11 and outputs the detection result. The water temperature sensor 207 is provided, for example, in the vicinity of the engine 11.

The control device 100 corresponds to the Rankine cycle control device according to the present invention. The control device 100 stores a CPU (Central Processing Unit) which is an arithmetic processing unit, a ROM (Read Only Memory) which is a storage element for storing programs and arithmetic parameters used by the CPU, parameters which are appropriately changed in the execution of the CPU, and the like. It is composed of a RAM (Random Access Memory) or the like, which is a storage element for temporary storage.

The control device 100 controls the operation of each device constituting the charging system 10. For example, the control device 100 controls the operation of each device by outputting an operation instruction using an electric signal to each device to be controlled. Specifically, the control device 100 controls the drive and power generation of the traveling motor generator 41 by controlling the operation of the inverter device of the traveling motor generator 41. Further, the control device 100 controls the drive and power generation of the pump motor generator 61 by controlling the operation of the inverter device of the pump motor generator 61. Further, the control device 100 controls the amount of recirculation of the operating medium adjusted by the flow rate adjusting mechanism 72 by controlling the operation of the flow rate adjusting mechanism 72.

Further, the control device 100 receives the information output from each device. Communication between the control device 100 and each device is realized by using, for example, CAN (Control Area Network) communication. For example, the control device 100 receives various detection results output from the pump rotation speed sensor 201, the steam temperature sensor 205, and the water temperature sensor 207. The function of the control device 100 according to the present embodiment may be divided by a plurality of control devices, and in that case, the plurality of control devices may be connected to each other via a communication bus such as CAN. ..

The control device 100 according to the present embodiment controls the amount of recirculation of the working medium according to the steam temperature. As a result, the vapor pressure can be appropriately adjusted according to the steam temperature, so that the device can be miniaturized more effectively. The details of such a control device 100 will be described later.

<2. Control device>
Subsequently, the details of the control device 100 according to the present embodiment will be described with reference to FIGS. 2 to 5.

The control device 100 controls the amount of recirculation of the working medium adjusted by the flow rate adjusting mechanism 72 by controlling the operation of the flow rate adjusting mechanism 72. Specifically, the control device 100 can control the amount of recirculation of the working medium by controlling the flow path area of the bypass flow path 76 by outputting an operation instruction to the flow rate adjusting mechanism 72. Further, the control device 100 can control the flow rate sent to the inflator 75 out of the discharge flow rate of the pump 73 by controlling the recirculation amount of the working medium. As a result, it is possible to adjust the difference between the flow rate sent to the inflator 75 and the discharge amount of the inflator 75 in the discharge flow rate of the pump 73. Therefore, it is possible to adjust the steam volume flow rate corresponding to the volume of the working medium of the gas phase supplied to the expander 75. As described above, the steam volume flow rate corresponds to, in other words, the volume of the working medium of the gas phase passing through the expander 75 per unit time.

The control device 100 according to the present embodiment controls the amount of recirculation of the working medium adjusted by the flow rate adjusting mechanism 72 according to the steam temperature. Therefore, the flow rate sent to the inflator 75 out of the discharge flow rate of the pump 73 can be controlled according to the steam temperature. Therefore, the steam volume flow rate can be adjusted according to the steam temperature.

Specifically, in the control device 100, the vapor pressure, which is the pressure of the working medium of the gas phase supplied to the expander 75, approaches the target vapor pressure as the target value of the vapor pressure set according to the steam temperature. As described above, the amount of recirculation of the working medium is controlled. The target vapor pressure is preferentially set to the upper limit value P10 of the vapor pressure set in advance based on, for example, various design specifications of the vehicle. Specifically, the upper limit value P10 can be set from the viewpoint of ensuring a larger amount of power generation based on the mechanical strength of the members constituting the Rankine cycle 70 or the physical properties of the working medium. Hereinafter, the relationship between the steam temperature and the target vapor pressure will be described with reference to FIGS. 2 and 3.

FIG. 2 is an explanatory diagram showing an example of the vapor pressure curve C10 of the working medium. In FIG. 2, a vapor pressure curve C10 showing the boiling point for each pressure when the temperature of the working medium is taken on the horizontal axis and the pressure of the working medium is taken on the vertical axis is shown. The vapor pressure curve C10 shown in FIG. 2 corresponds to a part of the phase diagram of the working medium, and in FIG. 2, the melting curve showing the freezing point for each pressure and the sublimation curve showing the sublimation pressure for each temperature are shown. , Omitted.

As shown in FIG. 2, the boiling point corresponding to the upper limit value P10 of the vapor pressure is the temperature Tmb10 corresponding to the point D1 on the vapor pressure curve C10. In the region on the higher temperature side than the vapor pressure curve C10, the working medium becomes the gas phase, and in the region on the lower temperature side than the vapor pressure curve C10, the working medium becomes the liquid phase. Therefore, when the pressure of the working medium is the upper limit value P10 and the temperature of the working medium is higher than the temperature Tmb10, the working medium becomes a gas phase. Therefore, when the steam temperature is higher than the temperature Tmb10, the target vapor pressure is set to the upper limit value P10 as shown in FIG.

On the other hand, when the pressure of the working medium is the upper limit value P10 and the temperature of the working medium is lower than the temperature Tmb10, the working medium becomes a liquid phase. Here, the working medium becomes a gas phase at each temperature in a region below the saturated vapor pressure, which is the pressure corresponding to the point on the vapor pressure curve C10 shown in FIG. Therefore, when the steam temperature is the temperature Tmb10 or less, the target vapor pressure is set to, for example, the saturated vapor pressure for each vapor temperature. As shown in FIG. 2, the saturated vapor pressure decreases as the temperature of the working medium decreases. Therefore, when the steam temperature is the temperature Tmb10 or less, the target vapor pressure is specifically set to a smaller value as the steam temperature is lower, as shown in FIG.

Specifically, the control device 100 controls the amount of recirculation of the working medium according to the steam temperature so that the vapor pressure becomes the target vapor pressure shown in FIG. The control device 100 controls the amount of recirculation of the working medium by controlling the operation of the flow rate adjusting mechanism 72 using, for example, the map M10 shown in FIG. The map M10 is an example of a map showing the relationship between the steam temperature and the flow path area of the bypass flow path 76, and is stored in advance in the storage element of the control device 100. The control device 100 controls the operation of the flow rate adjusting mechanism 72 so that the flow path area of the bypass flow path 76 becomes a value corresponding to the current steam temperature in the map M10. Since the recirculation amount of the working medium has a correlation with the flow path area of the bypass flow path 76, the relationship between the steam temperature and the recirculation amount of the working medium is the steam temperature represented by the map M10 and the flow path of the bypass flow path 76. Corresponding to the relationship with the area, for example, the relationship shown in FIG.

The control device 100 can acquire the current steam temperature value based on the detection result output from the steam temperature sensor 205. Further, the control device 100 may estimate the current steam temperature based on the detection result output from the water temperature sensor 207 and the detection value of the rotation speed of the engine 11. In that case, the control device 100 is configured to be able to receive the detection result output from a sensor (not shown) capable of detecting the rotation speed of the engine 11. As a result, the control device 100 can acquire the detected value of the rotation speed of the engine 11.

Here, the discharge flow rates of the pump 73 and the expander 75 can change according to the rotation speed of the pump 73. Therefore, the relationship between the recirculation amount of the working medium and the steam volume flow rate may differ depending on the rotation speed of the pump 73. Therefore, specifically, the control device 100 may control the operation of the flow rate adjusting mechanism 72 by using maps different from each other according to the rotation speed of the pump 73. Each map shows the relationship between the steam temperature and the flow path area of the bypass flow path 76 with respect to the rotation speed of the corresponding pump 73. Each map is set so that the vapor pressure can be adjusted to the target vapor pressure shown in FIG. 3 for the rotation speed of the corresponding pump 73. Thereby, the control device 100 can control the recirculation amount of the working medium according to the steam temperature so that the vapor pressure becomes the target vapor pressure shown in FIG. 3 regardless of the rotation speed of the pump 73. .. Hereinafter, in order to facilitate understanding, the control of the recirculation amount of the working medium performed by the control device 100 will be described with reference to the map M10 as an example of each of such maps.

As shown in FIG. 3, when the steam temperature is higher than the temperature Tmb10, the target vapor pressure is the upper limit value P10 regardless of the steam temperature. According to the ideal gas law, the vapor pressure correlates with the value obtained by dividing the vapor temperature by the vapor volume flow rate. Therefore, when the steam temperature is higher than the temperature Tmb10, the vapor pressure is maintained at the upper limit value P10 regardless of the steam temperature by controlling the recirculation amount of the working medium so that the steam volume flow rate increases as the steam temperature rises. can do. Specifically, in the map M10, as shown in FIG. 4, when the steam temperature is higher than the temperature Tmb10, the flow path area of the bypass flow path 76 is set to a larger value as the steam temperature is higher. Thereby, as shown in FIG. 5, when the steam temperature is higher than the temperature Tmb10, the recirculation amount of the working medium can be increased as the steam temperature becomes higher. Therefore, when the steam temperature is higher than the temperature Tmb10, the steam volume flow rate can be increased as the steam temperature becomes higher.

As described above, when the steam temperature is higher than the boiling point Tmb10 of the working medium at the upper limit value P10 which is a predetermined pressure, the control device 100 may increase the recirculation amount of the working medium as the steam temperature becomes higher. Good. Thereby, when the steam temperature is higher than the temperature Tmb10, the steam volume flow rate can be increased as the steam temperature becomes higher. Therefore, when the steam temperature is higher than the temperature Tmb10, the vapor pressure can be maintained at the upper limit value P10 regardless of the steam temperature.

As described above, when the steam temperature is higher than the temperature Tmb10, by maintaining the vapor pressure at the upper limit value P10 regardless of the steam temperature, it is possible to prevent the vapor pressure from becoming excessively high as the steam temperature rises. can do. Thereby, it is possible to prevent the inflator 75 from being damaged. Further, when the steam temperature is higher than the temperature Tmb10, by maintaining the vapor pressure at the upper limit value P10 regardless of the steam temperature, it is possible to prevent the vapor pressure from becoming excessively low as the steam temperature decreases. it can. Thereby, it is possible to prevent the amount of power generation from decreasing due to the decrease in the rotational energy generated by the expander 75.

Further, as shown in FIG. 3, when the steam temperature is the temperature Tmb10 or less, the target vapor pressure is set to a smaller value as the steam temperature is lower. Specifically, when the steam temperature is the temperature Tmb10 or less, the target vapor pressure is set to the saturated vapor pressure for each vapor temperature. According to the ideal gas law, the vapor pressure decreases as the vapor volume flow rate increases. Therefore, when the steam temperature is Tmb10 or less, the vapor pressure is made smaller as the steam temperature is lower by controlling the recirculation amount of the working medium so that the steam volume flow rate increases as the steam temperature becomes lower. be able to. Thereby, when the steam temperature is the temperature Tmb10 or less, the vapor pressure can be matched with the saturated vapor pressure for each steam temperature. Specifically, in the map M10, as shown in FIG. 4, when the steam temperature is Tmb10 or less, the flow path area of the bypass flow path 76 is set to a larger value as the steam temperature is lower. As a result, as shown in FIG. 5, when the steam temperature is Tmb10 or less, the recirculation amount of the working medium can be increased as the steam temperature becomes lower. Therefore, when the steam temperature is Tmb10 or less, the steam volume flow rate can be increased as the steam temperature becomes lower.

As described above, when the steam temperature is equal to or lower than the boiling point temperature Tmb10 of the working medium at the upper limit value P10, the control device 100 may increase the recirculation amount of the working medium as the steam temperature becomes lower. Thereby, when the steam temperature is Tmb10 or less, the steam volume flow rate can be increased as the steam temperature becomes lower. Therefore, when the steam temperature is the temperature Tmb10 or less, the vapor pressure can be made smaller as the steam temperature is lower, so that the vapor pressure can be matched with the saturated vapor pressure for each steam temperature.

As described above, when the steam temperature is Tmb10 or less, it is possible to prevent the pressure of the working medium from exceeding the saturated vapor pressure by matching the vapor pressure with the saturated vapor pressure for each steam temperature. .. As a result, it is possible to prevent a part of the working medium from staying in the heat exchanger 74 without evaporating, so that it is possible to prevent the liquid level of the working medium stored in the tank 79 from dropping. Here, air may be sucked by the pump 73 due to the decrease in the liquid level of the working medium stored in the tank 79. In such a case, cavitation may occur in the pump 73, so that abnormal noise or erosion in the pump 73 may occur. Therefore, by preventing the pressure of the working medium from exceeding the saturated vapor pressure, it is possible to prevent such abnormal noise and erosion in the pump 73. Further, when the steam temperature is the temperature Tmb10 or less, the vapor pressure can be made a relatively high value for each steam temperature by matching the vapor pressure with the saturated vapor pressure for each steam temperature. As a result, a relatively high amount of power generation can be secured for each steam temperature.

As described above, the control device 100 according to the present embodiment controls the amount of recirculation of the working medium adjusted by the flow rate adjusting mechanism 72 according to the steam temperature. Therefore, the flow rate sent to the inflator 75 out of the discharge flow rate of the pump 73 can be controlled according to the steam temperature. Therefore, the steam volume flow rate can be adjusted according to the steam temperature. As a result, in the Rankine cycle 70 in which the pump 73 and the inflator 75 are respectively connected to the pump motor generator 61, the number of parts such as a mechanism for adjusting the discharge amount per rotation of the pump 73 or the inflator 75 is relatively large. The vapor pressure can be appropriately adjusted according to the steam temperature without providing a mechanism. Therefore, the device can be miniaturized more effectively.

<3. Conclusion>
As described above, according to the present embodiment, in the Rankine cycle 70, the pump 73 and the inflator 75 are respectively connected to the pump motor generator 61. Further, in the Rankine cycle 70, the bypass flow path 76 that communicates the downstream side and the upstream side with respect to the pump 73 in the working medium flow path 71 and the inside of the bypass flow path 76 are upstream from the downstream side of the pump 73 in the working medium flow path 71. A flow rate adjusting mechanism 72 that can adjust the amount of recirculation, which is the flow rate of the working medium that recirculates to the side, is provided. Further, the control device 100 controls the amount of recirculation of the working medium adjusted by the flow rate adjusting mechanism 72 according to the steam temperature. As a result, the vapor pressure can be appropriately adjusted according to the steam temperature without providing a mechanism having a relatively large number of parts such as a mechanism for adjusting the discharge amount per rotation of the pump 73 or the expander 75. Therefore, the device can be miniaturized more effectively.

In the above description, an example in which the control device 100 controls the operation of the flow rate adjusting mechanism 72 by using the map M10 has been described, but the control of the flow rate adjusting mechanism 72 by the control device 100 is not limited to such an example. For example, the control device 100 may control the operation of the flow rate adjusting mechanism 72 by using feedback control. Specifically, the control device 100 may control the operation of the flow rate adjusting mechanism 72 by outputting a control command according to the difference between the detected value of the vapor pressure and the target vapor pressure to the flow rate adjusting mechanism 72. .. In that case, the charging system 10 is provided with a sensor capable of detecting the vapor pressure, and the control device 100 can acquire the detected value of the vapor pressure by receiving the detection result output from the sensor. The sensor is provided, for example, on the upstream side of the expander 75 in the working medium flow path 71 of the Rankine cycle 70.

Further, in the above description, an example in which the Rankine cycle control device according to the present invention is applied to a hybrid vehicle has been described, but the technical scope of the present invention is not limited to such an example. For example, the Rankine cycle control device according to the present invention may be applied to a vehicle that travels by a driving force output from an engine 11 and does not have a traveling motor generator 41 and a high-voltage battery 31 as driving sources. In that case, the pump motor generator 61 may be electrically connected to a low voltage battery that supplies power to various devices in the vehicle. Even when the Rankine cycle control device according to the present invention is applied to a hybrid vehicle, the pump motor generator 61 may be electrically connected to a low-voltage battery that supplies electric power to various devices in the vehicle. ..

Further, in the above description, an example in which the driving force generated by the operation of the engine 11 is transmitted to the driving wheels 21 via the driving force transmission system 51 has been described. Not limited. For example, the driving force generated by the operation of the engine 11 may be transmitted to a generator (not shown) connected to the engine 11 and used for power generation by the generator. The electric power generated by the generator may be configured to be stored in the high voltage battery 31.

Further, in the above description, an example in which the Rankine cycle 70 generates mechanical energy by exchanging heat with the cooling water for recovering the waste heat of the engine 11 of the vehicle has been described. The scope is not limited to such examples. For example, the Rankine cycle 70 may generate mechanical energy by exchanging heat with the exhaust gas having waste heat of the engine 11 of the vehicle. In such a case, the working medium flow path 71 and the exhaust gas piping may be connected to the heat exchanger 74.

Further, in the above description, an example in which the Rankine cycle control device according to the present invention is applied to a vehicle has been described, but the technical scope of the present invention is not limited to such an example. For example, the Rankine cycle control device according to the present invention can be applied to other mobile objects such as ships and facilities such as factories.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or applications within the scope of the technical idea described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

10 Charging system 11 Engine 13 Cooling water flow path 21 Drive wheel 31 High voltage battery 41 Driving motor generator 51 Driving force transmission system 61 Pump motor generator 70 Rankine cycle 71 Operating medium flow path 72 Flow control mechanism 73 Pump 74 Heat exchanger 75 Inflator 76 Bypass flow path 77 Condenser 79 Tank 100 Control device 201 Pump rotation speed sensor 205 Steam temperature sensor 207 Water temperature sensor

Claims (5)

The working medium flow path, which is the flow path through which the heated working medium circulates,
A pump provided in the working medium flow path and circulating the working medium in the working medium flow path,
An expander provided in the working medium flow path to expand the working medium to generate rotational energy,
In the Rankine cycle controller, including
The pump and the inflator are respectively connected to a motor generator, and the pump and the inflator are connected to each other.
In the Rankine cycle, a bypass flow path communicating the downstream side and the upstream side of the pump in the working medium flow path and the inside of the bypass flow path are returned from the downstream side to the upstream side of the pump in the working medium flow path. A flow rate adjusting mechanism capable of adjusting the amount of recirculation, which is the flow rate of the working medium, is provided.
Wherein the control device, the recirculation amount to be adjusted by the flow rate adjusting mechanism, and controlled in accordance with the steam temperature is a temperature of the working medium of the gas phase supplied to the expander,
When the steam temperature is higher than the boiling point of the working medium at a predetermined pressure, the inflator is subjected to a flow rate sent from the pump to the inflator by increasing the amount of recirculation as the steam temperature becomes higher. Relatively increase the discharge rate of
Rankine cycle controller. When the steam temperature is equal to or lower than the boiling point of the working medium at the predetermined pressure, the control device is sent from the pump to the inflator by increasing the amount of recirculation as the steam temperature decreases. The Rankine cycle control device according to claim 1 , wherein the discharge amount of the expander is relatively large with respect to the flow rate. The working medium flow path is provided with a condenser that condenses the working medium of the gas phase that has passed through the expander.
The bypass flow path is connected to the upstream side of the pump in the working medium flow path and downstream of the condenser in the working medium flow path.
The Rankine cycle control device according to claim 1 or 2. The working medium flow path is provided with a tank in which the working medium sucked up by the pump is stored.
The bypass flow path is connected to the upstream side of the pump in the working medium flow path and downstream of the tank in the working medium flow path.
The Rankine cycle control device according to any one of claims 1 to 3. The flow rate adjusting mechanism according to any one of claims 1 to 4 , wherein the flow rate adjusting mechanism includes an orifice provided in the bypass flow path and capable of adjusting the flow rate amount by adjusting the flow path area of the bypass flow path. Rankine cycle controller.

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