JP2017066886A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle control device capable of preventing an abrupt increase in a rotation speed of an expander.SOLUTION: A vehicle control device comprises: a flow passage to circulate a working medium to be heated by waste heat of a vehicle engine; a Rankine cycle which is installed in the flow passage and includes an expander generating mechanical energy by expanding the working medium; a first generator which generates power using the mechanical energy generated by the expander and stores the generated power in a battery; a second generator which generates the power using kinetic energy of a vehicle when brakes are applied thereto and stores the generated power in the battery; a pump control section which controls drive of a Rankine cycle pump to circulate the working medium; and a prediction section which predicts whether or not braking operation of the vehicle is going to be started. When the prediction section predicts that the braking operation of the vehicle is going to be started, the pump control section reduces a rotation speed of the Rankine cycle pump in accordance with a prediction result of the prediction section.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle control device.

  Conventionally, a technique for regenerating energy that has been discarded in a vehicle and using it for power generation is known. For example, a technique related to power generation using waste heat generated in a vehicle (hereinafter also referred to as thermoelectric power generation) and a technique related to power generation using vehicle kinetic energy during vehicle braking (hereinafter also referred to as braking power generation) have been proposed. ing.

  For example, in Patent Document 1, in order to efficiently recover energy and improve the fuel efficiency of a vehicle, power generation is performed using the power of the moving body so that the voltage value of the power supply system of the moving body becomes a predetermined adjustment voltage value. The generated power generation power is supplied to the power supply system, and the thermoelectric power generated using the heat energy of the heat source in the moving body is supplied to the power supply system so that the voltage value of the power supply system does not exceed the preset upper limit value. A technique for controlling thermoelectric power is disclosed.

JP 2007-154800 A

  By the way, thermoelectric power generation is realized by, for example, a Rankine cycle that generates mechanical energy using a working medium heated by waste heat of an engine. Specifically, mechanical energy is generated by expanding the working medium with an expander provided in a flow path through which the working medium circulates. A thermoelectric generator connected to the expander generates electric power using the mechanical energy, and the generated electric power is stored in the battery. On the other hand, the braking power generation is realized by, for example, a motor / generator that generates a braking force at the time of braking the vehicle and generates power using the kinetic energy of the wheels. The electric power generated by the motor / generator is stored in the battery. The motor / generator corresponds to a generator for braking power generation.

  When both thermoelectric generation and braking power generation are performed, the battery voltage matches the value of the higher output voltage of the output voltage of the thermoelectric generator and the output voltage of the motor / generator. Therefore, power is not supplied from the generator with the lower output voltage to the battery. Here, from the viewpoint of improving energy efficiency, charging of the battery by braking power generation may be given priority over charging of the battery by thermoelectric power generation. In such a case, during braking of the vehicle, the output voltage of the thermoelectric generator is set to be lower than the output voltage of the motor / generator. Therefore, when the vehicle is braked, power is not supplied to the battery from the thermoelectric generator connected to the Rankine cycle expander. Therefore, when braking of the vehicle is started, the power generation by the thermoelectric generator is stopped, and the rotation load of the expander connected to the thermoelectric generator is lightened. May rise. Thereby, generation | occurrence | production of abnormal noise and the burning of parts may arise.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle control device capable of preventing a rapid increase in the rotational speed of an expander. It is in.

  In order to solve the above-described problem, according to an aspect of the present invention, a working medium heated by waste heat of a vehicle engine circulates, and a mechanical energy is provided by expanding the working medium provided in the passage. A Rankine cycle including an expander that generates a first generator, a first generator that generates electric power using the mechanical energy generated by the expander, and stores the generated electric power in a battery, and the vehicle during braking of the vehicle And a second generator for storing the generated electric power in the battery, wherein the pump controls the drive of the Rankine cycle pump for circulating the working medium. A control unit, and a prediction unit that predicts whether or not braking of the vehicle is started, and the pump control unit predicts that braking of the vehicle is started by the prediction unit When it is, according to the prediction result of the prediction unit, the decreasing the rotational speed of the Rankine cycle pump control apparatus for a vehicle is provided.

  The Rankine cycle includes a bypass channel that connects the upstream side and the downstream side of the expander of the channel and a bypass valve that can open and close the bypass channel, and is predicted to start braking of the vehicle. When the rotation speed of the expander is higher than a predetermined rotation speed or when the vapor pressure of the working medium supplied to the expander is higher than a predetermined pressure, the bypass valve is opened. A valve control unit may be provided.

  The bypass valve control unit opens the bypass valve so that the rotation speed of the expander approaches the target rotation speed after opening the bypass valve when the braking of the vehicle is predicted to start. May be controlled.

  When it is predicted that braking of the vehicle will start, the bypass valve control unit opens the bypass valve, and then causes the vapor pressure of the working medium supplied to the expander to approach a target pressure. The opening degree of the bypass valve may be controlled.

  The prediction unit predicts whether or not braking of the vehicle is to be terminated, and the pump control unit predicts by the prediction unit when the prediction unit predicts that braking of the vehicle is to be terminated. Depending on the result, the number of rotations of the Rankine cycle pump may be increased.

  The prediction unit predicts whether or not braking of the vehicle is to be ended, and the bypass valve control unit is configured to switch the bypass valve when the prediction unit predicts that braking of the vehicle is to be ended. It may be closed.

  The prediction unit may predict whether or not braking of the vehicle is started based on a situation in a traveling direction of the vehicle.

  The prediction unit may predict whether or not braking of the vehicle is started based on a shape of a traveling path ahead of the vehicle.

  The prediction unit may predict whether braking of the vehicle is started based on an inter-vehicle distance from a vehicle ahead of the vehicle.

  As described above, according to the present invention, it is possible to prevent a rapid increase in the rotational speed of the expander.

1 is a schematic diagram illustrating an example of a schematic configuration of a vehicle charging system according to an embodiment of the present invention. It is explanatory drawing which shows an example of a function structure of the control apparatus which concerns on the same embodiment. It is a flowchart which shows an example of the flow of the 1st process which the control apparatus which concerns on the same embodiment performs. It is explanatory drawing for demonstrating the fluctuation | variation of the rotation speed of the expander at the time of the braking of a vehicle when the 1st process which concerns on the embodiment is performed. It is explanatory drawing for demonstrating the fluctuation | variation of the rotation speed of the expander at the time of the braking of a vehicle when the process which concerns on a comparative example is performed. It is a flowchart which shows an example of the flow of the 2nd process which the control apparatus which concerns on the same embodiment performs. It is explanatory drawing for demonstrating the fluctuation | variation of the rotation speed of the expander at the time of the braking of a vehicle when the 2nd process which concerns on the embodiment is performed.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. Configuration of charging system>
First, a schematic configuration of a vehicle charging system 10 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram illustrating an example of a schematic configuration of a charging system 10 according to the present embodiment. As shown in FIG. 1, the charging system 10 includes an engine 14, a cooling water passage 16, a driving force transmission system 18, driving wheels 22, a high voltage battery 30, a motor / generator 40, and a thermoelectric generator. The generator 60, the Rankine cycle 70, the external recognition part 204, the rotation speed sensor 208, the vapor pressure sensor 212, and the control apparatus 100 are provided.

  The engine 14 is driven or stopped according to the traveling state of the vehicle. For example, the engine 14 is driven or stopped according to the required torque while the vehicle is running. The driving force generated by the operation of the engine 14 is transmitted to the driving wheels 22 via the driving force transmission system 18. A cooling water passage 16 through which cooling water circulates is provided in the cylinder block and cylinder head of the engine 14 in order to cool the engine 14. Waste heat of the engine 14 is recovered by cooling water circulating in the cooling water flow path 16. The cooling water passage 16 is connected to the heat exchanger 78 of the Rankine cycle 70 outside the engine 14, and performs heat exchange with the working medium of the Rankine cycle 70 in the heat exchanger 78.

  The high voltage battery 30 is an example of a battery according to the present invention. The high voltage battery 30 is a high voltage (for example, 200V) power supply source. Specifically, the high voltage battery 30 supplies power to a motor / generator 40 that outputs the driving force of the vehicle, and also supplies power to a low voltage battery that supplies power to various devices in the vehicle. The high voltage battery 30 stores the electric power generated by the thermoelectric generator 60 and the electric power generated by the motor / generator 40, respectively.

  The motor / generator 40 has a function as a driving motor that generates driving force of the vehicle. The motor / generator 40 is an example of a second generator according to the present invention. The motor / generator 40 generates electric power using the kinetic energy of the vehicle when the vehicle is braked, and stores the generated electric power in the high-voltage battery 30. It functions as a power generator. The motor / generator 40 includes, for example, a three-phase AC motor and an inverter device, and is electrically connected to the high voltage battery 30 via the inverter device. Note that the inverter device also has a function as a converter device.

  When the motor / generator 40 functions as a driving motor, the DC power supplied from the high voltage battery 30 is converted into AC power by the inverter device and supplied to the motor. Thereby, a driving force is generated by the motor. The driving force generated by the motor / generator 40 is transmitted to the driving wheels 22 via the driving force transmission system 18. The control device 100 controls generation of driving force by the motor / generator 40 by controlling the inverter device.

  When the motor / generator 40 functions as a generator for braking power generation when the vehicle is braked, the inverter is controlled by the control device 100, whereby the motor generates power using the rotational energy of the drive wheels 22 and generates power. The alternating current power is converted into direct current power by the inverter device and stored in the high voltage battery 30. Thereby, resistance is given to rotation of the driving wheel 22 and braking force is generated. The control device 100 controls the output voltage of the motor / generator 40 by controlling the inverter device.

  The Rankine cycle 70 generates mechanical energy using the waste heat of the engine 14 of the vehicle. As shown in FIG. 1, the Rankine cycle 70 includes a working medium flow path 72, a Rankine cycle pump 74, a heat exchanger 78, an expander 86, a condenser 90, a tank 98, and a bypass flow path 82. And a bypass valve 94.

  The working medium channel 72 is a channel through which the working medium of the Rankine cycle 70 circulates. As the working medium, for example, water, chlorofluorocarbon or alcohol can be applied.

  The Rankine cycle pump 74 is a pump that sucks up the working medium stored in the tank 98 and circulates the working medium in the working medium flow path 72. The drive of the Rankine cycle pump 74 is controlled by the control device 100. Specifically, the control device 100 controls the rotation speed of the Rankine cycle pump 74. The Rankine cycle pump 74 is configured to be driven by, for example, an electric motor, and the electric motor drives the Rankine cycle pump 74 based on an operation instruction from the control device 100.

  The working medium channel 72 and the cooling water channel 16 are connected to the heat exchanger 78. In the heat exchanger 78, heat exchange is performed between the working medium and the cooling water. Thereby, the working medium is heated and vaporized by the cooling water having the waste heat of the engine 14.

  The expander 86 expands the working medium vaporized by the heat exchanger 78 to generate mechanical energy. Specifically, in the expander 86, 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, whereby the rotating body connected to the impeller Energy of rotational motion is generated. The expander 86 is connected to the thermoelectric generator 60, and mechanical energy generated by the expander 86 is transmitted to the thermoelectric generator 60.

  The condenser 90 cools and condenses the vapor-phase working medium that has passed through the expander 86 by air blown by a fan or the like. The working medium condensed by the condenser 90 is stored in the tank 98.

  The bypass channel 82 is a channel that connects the upstream side and the downstream side of the expander 86 of the working medium channel 72. The bypass passage 82 is provided with a bypass valve 94 that can open and close the bypass passage 82. In a state where the bypass flow path 82 is closed by the bypass valve 94, the working medium flows through the Rankine cycle pump 74, the heat exchanger 78, the expander 86, the condenser 90, and the tank 98 in this order. The drive of the bypass valve 94 is controlled by the control device 100. For example, an electromagnetic valve is applied as the bypass valve 94. The bypass valve 94 may be a valve whose opening degree is continuously variable, or may be a valve capable of switching only two opening degrees of an open state and a closed state.

  The thermoelectric generator 60 is an example of a first generator according to the present invention. The thermoelectric generator 60 generates power using the mechanical energy generated by the expander 86 and stores the generated power in the high voltage battery 30. The thermoelectric generator 60 includes, for example, a three-phase AC motor and a converter device, and is electrically connected to the high voltage battery 30 via the converter device. The motor is connected to the rotating body of the expander 86, and energy of rotational motion of the rotating body is transmitted to the motor. When the converter device is controlled by the control device 100, power is generated by the motor using the energy of the rotational motion transmitted to the motor, and the generated AC power is converted into DC power by the converter device. 30 is stored. The control device 100 controls the output voltage of the thermoelectric generator 60 by controlling the converter device.

  The external recognition unit 204 includes a pair of left and right cameras having an image sensor such as a CCD sensor or a CMOS sensor, images external environment outside the vehicle, and displays information indicating the situation in the traveling direction of the vehicle as image information. Can be recognized as. The external recognition unit 204 outputs information indicating the acquired situation of the traveling direction of the vehicle to the control device 100. In addition, when using information indicating a situation in the traveling direction of the vehicle included in information acquired from the outside such as navigation information, the external recognition unit 204 may be omitted from the configuration of the charging system 10.

  The rotation speed sensor 208 is provided in the vicinity of the rotating body of the expander 86, the thermoelectric generator 60 or the connection portion between the rotating body and the thermoelectric generator 60, and detects the rotation speed of the expander 86. Output the detection result.

  The vapor pressure sensor 212 is provided upstream of the expander 86 in the working medium flow path 72 of the Rankine cycle 70, detects the vapor pressure of the working medium supplied to the expander 86, and outputs the detection result.

  The control device 100 includes a CPU (Central Processing Unit) that is an arithmetic processing device, a ROM (Read Only Memory) that stores programs used by the CPU, operation parameters, and the like, a program used in the execution of the CPU, and changes as appropriate in its execution. RAM (Random Access Memory) that temporarily stores parameters to be stored.

  The control device 100 controls the operation of each device constituting the charging system 10. Specifically, the control device 100 issues an operation instruction to each actuator to be controlled using an electrical signal. More specifically, the control device 100 drives the Rankine cycle pump 74, drives the bypass valve 94, the output voltage of the thermoelectric generator 60, the output voltage of the motor / generator 40, and the driving force of the motor / generator 40. Control generation. Moreover, the control apparatus 100 receives the information output from each sensor. The control apparatus 100 may communicate with each sensor using CAN (Controller Area Network) communication. Note that the functions of the control device 100 according to the present embodiment may be divided by a plurality of control devices. In that case, the plurality of control devices may be connected to each other via a communication bus such as CAN. . Details of the control device 100 will be described later.

<2. Configuration of control device>
Next, the functional configuration of the control device 100 according to the present embodiment will be described with reference to FIG. FIG. 2 is an explanatory diagram illustrating an example of a functional configuration of the control device 100 according to the present embodiment. As shown in FIG. 2, the control device 100 includes a prediction unit 102, a pump control unit 104, and a bypass valve control unit 106.

(Prediction unit)
The prediction unit 102 predicts whether or not braking of the vehicle is started, and outputs a prediction result to the pump control unit 104 and the bypass valve control unit 106. For example, the prediction unit 102 determines at each time whether or not the vehicle will be braked in the near future, and the vehicle is braked in the near future from the state where it is determined that the vehicle is not braked in the near future. It is predicted that braking of the vehicle will start when the vehicle is switched to a state where it is determined that the vehicle will be released. The determination result at each time as to whether or not the vehicle will be braked in the near future is stored in, for example, the RAM of the control device 100. Further, various setting values used for determining whether or not the vehicle is to be braked in the near future are stored in, for example, the RAM of the control device 100.

  Specifically, the prediction unit 102 predicts whether or not braking of the vehicle is started based on the situation in the traveling direction of the vehicle. Accordingly, it is possible to appropriately predict whether or not braking of the vehicle is started in consideration of the situation in the traveling direction of the vehicle. For example, the prediction unit 102 predicts whether or not braking of the vehicle is started based on information indicating the situation in the traveling direction of the vehicle output from the external recognition unit 204. Further, the prediction unit 102 may predict whether or not braking of the vehicle is started based on information indicating a situation in the traveling direction of the vehicle included in information acquired from the outside such as navigation information. In the prediction of whether or not braking of the vehicle is to be started by the prediction unit 102, information indicating the shape of the traveling path ahead of the vehicle or the distance between the vehicle ahead of the vehicle as information indicating the state of the vehicle traveling direction Information indicating that can be used.

  The prediction unit 102 may predict whether or not braking of the vehicle is started based on the shape of the traveling path ahead of the vehicle. Accordingly, it is possible to appropriately predict whether or not braking of the vehicle is started in consideration of the shape of the traveling path ahead of the vehicle. The prediction unit 102 predicts whether braking of the vehicle is started based on, for example, the gradient of the traveling path ahead of the vehicle. Specifically, the prediction unit 102 determines that the vehicle will be braked in the near future when the traveling path ahead of the vehicle is a downhill at a certain time and the gradient is greater than a predetermined gradient. . On the other hand, when the traveling path ahead of the vehicle is an uphill at a certain time, or when the traveling path ahead of the vehicle is a downhill and the gradient is smaller than a predetermined gradient, the prediction unit 102 It is determined that the vehicle will not be braked in the near future. Here, the predetermined gradient is a threshold for determining whether or not the vehicle will be braked in the near future, and may be set according to the vehicle speed. The prediction unit 102 can predict whether or not braking of the vehicle will be started based on the determination result.

  In addition, the prediction unit 102 predicts whether braking of the vehicle is started based on the distance between the start position of the forward curve and the host vehicle, for example. Specifically, the prediction unit 102 determines that the vehicle will be braked in the near future when the distance between the start position of the forward curve and the own vehicle is smaller than a predetermined distance at a certain time. On the other hand, the prediction unit 102 determines that the vehicle is not braked in the near future when the distance between the start position of the forward curve and the own vehicle is larger than a predetermined distance at a certain time. Here, the predetermined distance is a threshold value for determining whether or not the vehicle is to be braked in the near future, and may be set according to the vehicle speed. The prediction unit 102 can predict whether or not braking of the vehicle will be started based on the determination result.

  The prediction unit 102 may predict whether or not braking of the vehicle is started based on the inter-vehicle distance from the vehicle ahead of the vehicle. Accordingly, it is possible to appropriately predict whether or not braking of the vehicle is started in consideration of the inter-vehicle distance with the vehicle in front of the vehicle. Specifically, the prediction unit 102, when at a certain time, the inter-vehicle distance from the vehicle ahead of the vehicle is smaller than a predetermined distance, and the relative speed of the host vehicle with respect to the vehicle ahead is larger than the predetermined speed, It is determined that the vehicle will be braked in the near future. On the other hand, the prediction unit 102 is in the near future when the distance between the vehicle and the vehicle ahead of the vehicle is larger than a predetermined distance or when the relative speed of the vehicle relative to the vehicle ahead is smaller than the predetermined speed. It is determined that the vehicle is not braked. Here, the predetermined distance and the predetermined speed are threshold values for determining whether or not the vehicle is to be braked in the near future, and the predetermined distance may be set according to the maximum speed of the vehicle, The predetermined speed may be set according to the set predetermined distance. The prediction unit 102 can predict whether or not braking of the vehicle will be started based on the determination result.

  Here, in the lane tracking control, when the inter-vehicle distance with the vehicle ahead of the vehicle becomes smaller than the set reference distance, braking of the vehicle may be automatically started. When a value obtained by subtracting the reference distance in the lane tracking control is smaller than a predetermined value at a certain time from the inter-vehicle distance with the vehicle ahead of the vehicle, the prediction unit 102 performs braking of the vehicle in the near future. May be determined. On the other hand, when a value obtained by subtracting the reference distance in the lane tracking control from the inter-vehicle distance with the vehicle ahead of the vehicle at a certain time is larger than a predetermined value, the prediction unit 102 brakes the vehicle in the near future. It may be determined that is not performed. Here, the predetermined value is a threshold value for determining whether or not the vehicle will be braked in the near future, and may be set according to the vehicle speed. The prediction unit 102 can predict whether or not braking of the vehicle will be started based on the determination result.

  Further, the prediction unit 102 predicts whether or not braking of the vehicle will be terminated, and outputs the prediction result to the pump control unit 104 and the bypass valve control unit 106. For example, when the prediction unit 102 switches from a state in which it is determined that braking of the vehicle is performed in the near future to a state in which it is determined that braking of the vehicle is not performed in the near future, braking of the vehicle is terminated. Predict. The prediction unit 102 uses the determination result used in the prediction of whether or not to start braking the vehicle as the determination result at each time as to whether or not the vehicle will be braked in the near future. It can be predicted whether or not will be terminated.

(Pump control unit)
The pump control unit 104 controls driving of the Rankine cycle pump 74. Specifically, the pump control unit 104 controls the rotation speed of the Rankine cycle pump 74. More specifically, the pump control unit 104 controls the rotation speed of the Rankine cycle pump 74 according to the prediction result by the prediction unit 102.

  When it is predicted by the prediction unit 102 that braking of the vehicle will be started, the pump control unit 104 reduces the rotational speed of the Rankine cycle pump 74 according to the prediction result by the prediction unit 102. Moreover, the pump control part 104 may increase the rotation speed of the Rankine cycle pump 74 according to the prediction result by the prediction part 102, when it is estimated by the prediction part 102 that braking of a vehicle will be complete | finished.

  In the following description, the Rankine cycle pump 74 based on the prediction result that the braking of the vehicle is finished after the decrease in the rotational speed of the Rankine cycle pump 74 based on the prediction result that the braking of the vehicle is started is started. Control of the drive of the Rankine cycle pump 74 by the pump control unit 104 during a period other than until the increase in the number of rotations is completed is referred to as normal control. In the normal control of the Rankine cycle pump 74, the pump control unit 104 sets the rotational speed of the Rankine cycle pump 74 based on, for example, a vehicle state quantity such as a fuel injection amount and an engine rotational speed.

(Bypass valve control unit)
The bypass valve control unit 106 controls driving of the bypass valve 94. Specifically, the bypass valve control unit 106 controls the opening degree of the bypass valve 94. More specifically, the bypass valve control unit 106 controls the opening degree of the bypass valve 94 according to the prediction result by the prediction unit 102. Note that various set values used for controlling the drive of the bypass valve 94 by the bypass valve control unit 106 are stored in the RAM of the control device 100, for example.

  The bypass valve control unit 106 determines that the vapor pressure of the working medium supplied to the expander 86 is predetermined when the rotation speed of the expander 86 is higher than a predetermined rotation speed when it is predicted that braking of the vehicle is started. If the pressure is higher than this, the bypass valve 94 may be opened.

  When it is predicted that braking of the vehicle will start, the bypass valve control unit 106 opens the bypass valve 94 and then adjusts the opening degree of the bypass valve 94 so that the rotational speed of the expander 86 approaches the target rotational speed. You may control. Further, when it is predicted that braking of the vehicle will be started, the bypass valve control unit 106 opens the bypass valve 94 and then causes the vapor pressure of the working medium supplied to the expander 86 to approach the target pressure. The opening degree of the bypass valve 94 may be controlled.

  Further, the bypass valve control unit 106 may close the bypass valve 94 when the prediction unit 102 predicts that braking of the vehicle will be terminated.

<3. Operation>
Then, with reference to FIGS. 3-7, the flow of the process which the control apparatus 100 which concerns on this embodiment performs is demonstrated. The process shown in FIG. 3 can be performed constantly after the vehicle control system is activated. Below, the prediction part 102 which concerns on this embodiment demonstrates the example which outputs the determination flag according to the determination result about whether the vehicle is braked in the near future at each time. The prediction unit 102 outputs “1” as a braking prediction determination flag indicating that it is determined that braking of the vehicle will be performed in the near future, and indicates that it is determined that braking of the vehicle is not performed in the near future. “0” is output as the braking prediction determination flag. The prediction unit 102 predicts that braking of the vehicle is started when the braking prediction determination flag is switched from “0” to “1”, and the braking prediction determination flag is switched from “1” to “0”. In addition, it is predicted that braking of the vehicle will be terminated.

(First processing flow)
FIG. 3 is a flowchart illustrating an example of a flow of the first process performed by the control device 100 according to the present embodiment. FIG. 4 is an explanatory diagram for explaining fluctuations in the rotational speed of the expander 86 during braking of the vehicle when the first processing according to the present embodiment is performed.

  As shown in FIG. 3, in the first process according to the present embodiment, first, the prediction unit 102 predicts whether or not braking of the vehicle is started (step S502). When the prediction unit 102 does not predict that braking of the vehicle will start (step S502 / NO), the prediction process of step S502 is repeated. On the other hand, when it is predicted that the braking of the vehicle will be started by the prediction unit 102 (step S502 / YES), the pump control unit 104 decreases the rotational speed of the Rankine cycle pump 74 (step S504).

  As shown in FIG. 4, at time T11, when the braking prediction determination flag is switched from “0” to “1”, the prediction unit 102 predicts that braking of the vehicle is started (step S502 / YES). ). And after time T11, the pump control part 104 reduces the rotation speed of the Rankine cycle pump 74 (step S504).

  After the process of step S504, as shown in FIG. 3, the prediction unit 102 predicts whether or not braking of the vehicle is to be ended (step S506). If the prediction unit 102 does not predict that braking of the vehicle will be terminated (step S506 / NO), the prediction process of step S506 is repeated. On the other hand, when the prediction unit 102 predicts that braking of the vehicle will be terminated (step S506 / YES), the pump control unit 104 performs a return process to normal control of the Rankine cycle pump 74 (step S508). The process shown in FIG. 3 ends.

  As shown in FIG. 4, when the braking prediction determination flag is switched from “1” to “0” at time T <b> 13, the prediction unit 102 predicts that braking of the vehicle is finished (step S <b> 506 / YES). ). And after time T13, the pump control part 104 returns the normal control of the Rankine cycle pump 74 by increasing the rotation speed of the Rankine cycle pump 74 (step S508).

  FIG. 5 is an explanatory diagram for explaining fluctuations in the rotational speed of the expander during braking of the vehicle when the process according to the comparative example is performed. In the comparative example, as compared with the present embodiment, the prediction of whether or not the braking of the vehicle is started and the prediction of whether or not the braking of the vehicle is ended are not performed. Therefore, in the comparative example, as compared with the present embodiment, the rotation of the Rankine cycle pump based on the prediction result as to whether or not the braking of the vehicle is started or the prediction result as to whether or not the braking of the vehicle is ended. The number is not controlled. In the following description, a comparative example is described in which the rotational speed of the Rankine cycle pump is decreased when braking of the vehicle is actually started and the rotational speed of the Rankine cycle pump is increased when braking of the vehicle is actually ended. To do.

  In the comparative example, as shown in FIG. 5, the decrease in the number of rotations of the Rankine cycle pump is started at time T91 when the braking of the vehicle is actually started. In addition, after time T91, since braking power generation is performed, the rotation load of the expander connected to the thermoelectric generator is light. Here, the lower the number of rotations of the Rankine cycle pump, the lower the amount of vaporized working medium that flows into the expander, so the amount of rotational motion energy generated by the expander can be reduced. However, in the comparative example, the rotation speed of the Rankine cycle pump at time T91 when the load of rotation of the expander is light is the rotation speed during normal control of the Rankine cycle pump. Therefore, the rotation speed of the expander may increase rapidly in the period between time T91 and time T92, which is the period immediately after the decrease in the rotation speed of the Rankine cycle pump is started. Thereby, generation | occurrence | production of abnormal noise or the burning of components may arise. As shown in FIG. 5, during the period between time T91 and time T92, the vapor pressure of the working medium supplied to the expander decreases as the rotation speed of the expander rapidly increases.

  On the other hand, according to the first process according to the present embodiment, as shown in FIG. 4, the decrease in the rotational speed of the Rankine cycle pump 74 is started at the time T <b> 11 when the braking of the vehicle is predicted to start. The Therefore, after the time T11, braking of the vehicle is actually started, and the rotational speed of the Rankine cycle pump 74 at time T12 when the braking power generation is started is lower than the rotational speed at the time of normal control. . Therefore, the energy amount of the rotational motion generated by the expander 86 at time T12 when the rotation load of the expander 86 is light can be reduced. Accordingly, it is possible to prevent a rapid increase in the rotational speed of the expander 86. Thereby, generation | occurrence | production of abnormal noise and the burning of components can be prevented.

  In the comparative example, as shown in FIG. 5, the increase in the number of rotations of the Rankine cycle pump is started at time T93 when the braking of the vehicle is actually ended. Since braking power generation is not performed after time T93 when braking of the vehicle is actually ended, it is possible to supply power from the thermoelectric generator to the high voltage battery. Here, as the number of rotations of the Rankine cycle pump increases, the amount of vaporized working medium flowing into the expander increases, so that the amount of energy of rotational motion generated by the expander can be increased. Thereby, the electric power generation amount by the thermoelectric generator can be increased. However, in the comparative example, the rotation speed of the Rankine cycle pump is lower than the rotation speed at the time of normal control at time T93 at which power can be supplied from the thermoelectric generator to the high voltage battery. . Therefore, between time T93 and time T94 when the increase in the rotational speed of the Rankine cycle pump ends, the amount of power generated by the thermoelectric generator is lower than the amount of power generated during normal control.

  On the other hand, according to the first process according to the present embodiment, as shown in FIG. 4, the increase in the rotational speed of the Rankine cycle pump 74 is started at the time T13 when the braking of the vehicle is predicted to end. The Therefore, at the time T14 before the time T15 when the vehicle braking is actually ended, the rotational speed of the Rankine cycle pump 74 can be increased in advance to the rotational speed at the time of normal control. Therefore, power generation efficiency can be improved after time T15 when power can be supplied from the thermoelectric generator 60 to the high voltage battery 30.

  In addition, when it is predicted that braking of the vehicle will be started, the response of the Rankine cycle pump 74 to the normal control is improved by continuously driving the Rankine cycle pump 74 without stopping. be able to.

(Second processing flow)
FIG. 6 is a flowchart illustrating an example of the flow of the second process performed by the control device 100 according to the present embodiment. FIG. 7 is an explanatory diagram for explaining fluctuations in the rotational speed of the expander 86 during braking of the vehicle when the second process according to the present embodiment is performed. The second process is different from the first process in that the drive of the bypass valve 94 is controlled by the bypass valve control unit 106. Specifically, in the second process, the process after the process (step S504) for reducing the rotational speed of the Rankine cycle pump 74 is different from the first process. A description of the processing in step S504 is omitted.

  In the second process according to the present embodiment, as shown in FIG. 6, after the pump control unit 104 reduces the rotational speed of the Rankine cycle pump 74 (step S <b> 504), the bypass valve control unit 106 performs the expansion. It is determined whether or not the rotational speed of the device 86 is higher than a predetermined rotational speed N100 (step S702). When the bypass valve control unit 106 determines that the rotation speed of the expander 86 is higher than the predetermined rotation speed N100 (step S702 / YES), the bypass valve control unit 106 opens the valve to adjust the opening degree of the bypass valve 94. Degree adjustment control is started (step S704). Specifically, in the opening degree adjustment control of the bypass valve 94, the bypass valve control unit 106 opens the bypass valve 94 and increases the opening degree of the bypass valve 94 so that the rotation speed of the expander 86 approaches the target rotation speed. Control. On the other hand, when the bypass valve control unit 106 does not determine that the rotation speed of the expander 86 is higher than the predetermined rotation speed N100 (step S702 / NO), the process proceeds to the determination process of step S506.

  As shown in FIG. 7, at time T21, when the braking prediction determination flag is switched from “0” to “1”, the prediction unit 102 is predicted to start braking the vehicle (step S502 / YES). ). And after time T21, the pump control part 104 reduces the rotation speed of the Rankine cycle pump 74 (step S504). At time T21, the bypass valve control unit 106 determines that the rotation speed of the expander 86 is higher than the predetermined rotation speed N100 (step S702 / YES). And after time T21, the bypass valve control part 106 starts the opening degree adjustment control of the bypass valve 94 (step S704). Specifically, the bypass valve control unit 106 opens the bypass valve 94 at time T21, and controls the opening degree of the bypass valve 94 so that the rotation speed of the expander 86 approaches the target rotation speed after time T21. To do.

  Here, the predetermined number of revolutions N100 used in the determination process in step S702 is that the braking of the vehicle is actually performed if the opening adjustment control of the bypass valve 94 is not performed when the braking of the vehicle is predicted to start. It is set to the rotation speed of the expander 86 in a case where a rapid increase in the rotation speed of the expander 86 may occur when started.

  According to the second processing according to the present embodiment, the inflating device 86 is opened by opening the bypass valve 94 at time T21 before time T22 when braking of the vehicle is actually started and braking power generation is started. A part of the working medium supplied to is sent from the upstream side of the expander 86 to the downstream side via the bypass flow path 82. Therefore, the inflow amount of the vaporized working medium to the expander 86 can be reduced. Thereby, the energy amount of the rotational motion produced | generated by the expander 86 in the time T22 when the rotation load of the expander 86 becomes a light state can be reduced more. Therefore, a rapid increase in the rotational speed of the expander 86 can be more effectively prevented. Thereby, generation | occurrence | production of abnormal noise and the burning of components can be prevented more effectively.

  Further, according to the second process according to the present embodiment, the opening degree of the bypass valve 94 is controlled so that the rotation speed of the expander 86 approaches the target rotation speed after time T21 when the bypass valve 94 is opened. The Here, the target rotational speed is set to a value that allows the Rankine cycle pump 74 to be continuously driven without stopping when it is predicted that braking of the vehicle will be started. Thereby, when it is predicted that braking of the vehicle will be started, the response of the Rankine cycle pump 74 to the normal control can be improved by continuously driving the Rankine cycle pump 74.

  In the process of step S506, as shown in FIG. 6, the prediction unit 102 predicts whether or not the braking of the vehicle will be terminated (step S506). If the prediction unit 102 does not predict that braking of the vehicle will be terminated (step S506 / NO), the prediction process of step S506 is repeated. On the other hand, when the prediction unit 102 predicts that the braking of the vehicle is to be ended (step S506 / YES), in the second process according to the present embodiment, the pump control unit 104 switches to normal control of the Rankine cycle pump 74. The return processing and the closing processing of the bypass valve 94 by the bypass valve control unit 106 are performed (step S706), and the processing shown in FIG.

  As shown in FIG. 7, at time T23, when the braking prediction determination flag is switched from “1” to “0”, the prediction unit 102 predicts that the braking of the vehicle is finished (step S506 / YES). ). And after time T23, the pump control part 104 returns the normal control of the Rankine cycle pump 74 by increasing the rotation speed of the Rankine cycle pump 74. In the second process according to the present embodiment, at time T23, the bypass valve control unit 106 closes the bypass valve 94 (step S706).

  According to the second process according to the present embodiment, as shown in FIG. 7, the bypass valve 94 is closed at the time T23 when the braking of the vehicle is predicted to end. As a result, the working medium that has been supplied from the upstream side to the downstream side of the expander 86 via the bypass channel 82 is supplied to the expander 86. Therefore, the inflow amount of the vaporized working medium to the expander 86 can be increased. Therefore, the energy amount of the rotational motion generated by the expander 86 can be increased in advance at a time before time T24 when braking of the vehicle is actually ended. Accordingly, the power generation efficiency can be improved after time T24 when power can be supplied from the thermoelectric generator 60 to the high voltage battery 30.

  In the above, the example in which the bypass valve control unit 106 starts the opening degree adjustment control of the bypass valve 94 when it is determined that the rotation speed of the expander 86 is higher than the predetermined rotation speed N100 has been described. The technical scope is not limited to such examples. For example, the bypass valve control unit 106 determines whether the vapor pressure of the working medium supplied to the expander 86 is higher than a predetermined pressure, and the vapor pressure of the working medium supplied to the expander 86 is the predetermined pressure. When it is determined that the value is higher, the bypass valve control unit 106 may start opening degree adjustment control of the bypass valve 94. Note that the predetermined pressure used in the determination process for determining whether or not to start the opening adjustment control is performed when the opening adjustment control of the bypass valve 94 is not performed when it is predicted that braking of the vehicle will start. Is set to the vapor pressure of the working medium supplied to the expander 86 when a sudden increase in the rotational speed of the expander 86 may occur when the braking of the engine is actually started.

  In the above, in the opening degree adjustment control of the bypass valve 94, the bypass valve control unit 106 opens the bypass valve 94 so that the rotational speed of the expander 86 approaches the target rotational speed after opening the bypass valve 94. Although an example of controlling the above has been described, the technical scope of the present invention is not limited to such an example. For example, in the opening adjustment control of the bypass valve 94, the bypass valve control unit 106 opens the bypass valve 94 and then sets the bypass valve 94 so that the vapor pressure of the working medium supplied to the expander 86 approaches the target pressure. The opening degree may be controlled. Note that the target rotational speed can be set to a value that allows the Rankine cycle pump 74 to be continuously driven without stopping when the braking of the vehicle is predicted to start.

<4. Conclusion>
As described above, according to the present embodiment, when the prediction unit 102 predicts that braking of the vehicle is started, the pump control unit 104 determines the Rankine cycle pump according to the prediction result by the prediction unit 102. The rotational speed of 74 is reduced. Thereby, braking of the vehicle is actually started, and the energy amount of the rotational motion generated by the expander 86 at the time when the rotation load of the expander 86 becomes light can be reduced. Accordingly, it is possible to prevent a rapid increase in the rotational speed of the expander 86. Thereby, generation | occurrence | production of abnormal noise and the burning of components can be prevented.

  In the above, the example in which the driving force generated by the operation of the engine 14 is transmitted to the driving wheel 22 via the driving force transmission system 18 has been described, but the technical scope according to the present invention is not limited to such an example. . For example, the driving force generated by the operation of the engine 14 may be transmitted to a generator (not shown) connected to the engine 14 and used for power generation by the generator. The electric power generated by the generator can be configured to be stored in the high voltage battery 30.

  In the above description, the Rankine cycle 70 has been described with respect to an example in which mechanical energy is generated by exchanging heat with cooling water that recovers waste heat of the engine 14 of the vehicle. The range is not limited to such an example. For example, the Rankine cycle 70 may generate mechanical energy by exchanging heat with exhaust gas having waste heat from the engine 14 of the vehicle. In such a case, the working medium flow path 72 and the exhaust gas piping may be connected to the heat exchanger 78.

  In the above description, the example in which the battery is the high voltage battery 30 has been described. However, the technical scope according to the present invention is not limited to the example, and for example, the battery is a low voltage that supplies power to various devices in the vehicle. A battery may be used. In such a case, the thermoelectric generator 60 and the motor / generator 40 are each electrically connected to a low voltage battery, and the electric power generated by the thermoelectric generator 60 in the thermal power generation and the motor / generator 40 in the braking power generation. The electric power generated in can be configured to be stored in a low-voltage battery.

  Further, the processing described using the flowchart in the present specification may not necessarily be executed in the order shown in the flowchart. Some processing steps may be performed in parallel. Further, additional processing steps may be employed, and some processing steps may be omitted.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can make various modifications or application examples within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Charging system 14 Engine 16 Cooling water flow path 18 Driving force transmission system 22 Drive wheel 30 High voltage battery 40 Motor generator 60 Thermoelectric generator 70 Rankine cycle 72 Working medium flow path 74 Rankine cycle pump 78 Heat exchanger 82 Bypass flow Path 86 Expander 90 Condenser 94 Bypass valve 98 Tank 100 Control device 102 Prediction unit 104 Pump control unit 106 Bypass valve control unit 204 External recognition unit 208 Rotation speed sensor 212 Vapor pressure sensor

Claims (9)

A Rankine cycle including a flow path through which a working medium heated by waste heat of a vehicle engine circulates and an expander provided in the flow path to expand the working medium to generate mechanical energy;
A first generator that generates electric power using the mechanical energy generated by the expander and stores the generated electric power in a battery;
A second generator for generating electric power using the kinetic energy of the vehicle during braking of the vehicle and storing the generated electric power in the battery;
In a vehicle control device comprising:
A pump control unit that controls driving of a Rankine cycle pump that circulates the working medium;
A prediction unit for predicting whether braking of the vehicle is started;
With
The pump control unit reduces the rotation speed of the Rankine cycle pump according to a prediction result by the prediction unit when the prediction unit predicts that braking of the vehicle is started.
Vehicle control device. The Rankine cycle includes a bypass channel that connects the upstream side and the downstream side of the expander of the channel and a bypass valve that can open and close the bypass channel,
When it is predicted that braking of the vehicle will start, when the rotational speed of the expander is higher than a predetermined rotational speed, or when the vapor pressure of the working medium supplied to the expander is higher than a predetermined pressure Includes a bypass valve control unit that opens the bypass valve.
The vehicle control device according to claim 1.   The bypass valve control unit opens the bypass valve so that the rotation speed of the expander approaches the target rotation speed after opening the bypass valve when the braking of the vehicle is predicted to start. The vehicle control device according to claim 2, which controls the vehicle.   When it is predicted that braking of the vehicle will start, the bypass valve control unit opens the bypass valve, and then causes the vapor pressure of the working medium supplied to the expander to approach a target pressure. The vehicle control device according to claim 2, wherein the opening degree of the bypass valve is controlled. The predicting unit predicts whether or not braking of the vehicle is terminated;
The pump control unit increases the number of rotations of the Rankine cycle pump according to a prediction result by the prediction unit when the prediction unit predicts that braking of the vehicle is ended.
The vehicle control device according to any one of claims 1 to 4. The predicting unit predicts whether or not braking of the vehicle is terminated;
The bypass valve control unit closes the bypass valve when the prediction unit predicts that braking of the vehicle is to be terminated.
The vehicle control device according to any one of claims 2 to 4.   The vehicle control device according to any one of claims 1 to 6, wherein the prediction unit predicts whether or not braking of the vehicle is started based on a situation in a traveling direction of the vehicle.   The vehicle control device according to claim 7, wherein the prediction unit predicts whether or not braking of the vehicle is started based on a shape of a traveling path ahead of the vehicle.   The vehicle control device according to claim 7, wherein the prediction unit predicts whether braking of the vehicle is started based on an inter-vehicle distance from a vehicle ahead of the vehicle.

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