JP6535262B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a control device of a vehicle.

  Conventionally, a technology is known which is used to generate energy by regenerating energy that has been discarded in a vehicle. For example, a technology related to power generation using waste heat generated in a vehicle (hereinafter also referred to as thermal power generation) and a technology related to power generation using the kinetic energy of the vehicle at the time of vehicle braking (hereinafter 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 the vehicle, the power generation of the moving body is performed using the power of the moving body such that the voltage value of the power supply system of the moving body becomes a predetermined adjustment voltage value. Supply the power generation system to the power supply system, and supply the heat generation power generated using the heat energy of the heat source of the moving body to the power supply system so that the voltage value of the power supply system does not exceed the preset upper limit Techniques for controlling thermal power generation are disclosed.

JP 2007-154800 A

  By the way, thermal power generation is realized by, for example, a Rankine cycle which 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. Then, a generator for thermal power generation connected to the expander generates power using the mechanical energy, and the generated 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 and generates electric power using the kinetic energy of the wheels at the time of braking the vehicle. 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 thermal power generation and braking power generation are performed, the battery voltage matches the value of the higher one of the output voltage of the thermal power 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 improvement of energy efficiency, charging of the battery by braking power generation may be prioritized in comparison with charging of the battery by thermal power generation. In such a case, when the vehicle is braked, the output voltage of the thermal generator is set to be lower than the output voltage of the motor generator. Therefore, at the time of braking of the vehicle, power is not supplied from the thermoelectric generator connected to the Rankine cycle expander to the battery. Therefore, when braking of the vehicle is started, power generation by the thermal power generation generator is stopped, and the load of rotation of the expander connected to the thermal power generation generator is lightened, so the number of rotations of the expander is rapid. May rise to As a result, the generation of noise and the burn-in of parts may occur.

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

  In order to solve the above problems, according to one aspect of the present invention, a flow path through which a working medium to be heated by waste heat of a vehicle engine circulates and the flow path are provided to expand the working medium for mechanical energy A first generator which generates electricity using the mechanical energy generated by the expander and stores the generated electric power in a battery; and the vehicle when the vehicle is braked And a second generator that generates electric power using the kinetic energy of the second power source and stores the generated electric power in the battery; and a pump that controls driving of a Rankine cycle pump that circulates the working medium. The control unit and a prediction unit that predicts whether or not braking of the vehicle is started are provided, 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 flow passage communicating the upstream and downstream sides of the flow passage with the expander and a bypass valve capable of opening and closing the bypass flow passage, and it is predicted that braking of the vehicle is started And bypassing the bypass valve if the number of revolutions of the expander is higher than a predetermined number of revolutions or the vapor pressure of the working medium supplied to the expander is higher than a predetermined pressure. A valve control unit may be provided.

  When it is predicted that the braking of the vehicle is started, the bypass valve control unit opens the bypass valve and then the opening degree of the bypass valve so that the rotation speed of the expander approaches a target rotation speed. May be controlled.

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

  The prediction unit predicts whether or not the braking of the vehicle is ended, and the pump control unit is predicted by the prediction unit when it is predicted that the braking of the vehicle is ended by the prediction unit Depending on the result, the rotational speed of the Rankine cycle pump may be increased.

  The prediction unit predicts whether or not the braking of the vehicle is terminated, and the bypass valve control unit is configured to select the bypass valve when it is predicted that the braking of the vehicle is terminated by the prediction unit. It may be closed.

  The prediction unit may predict whether braking of the vehicle is started based on the situation of the traveling direction of the vehicle.

  The prediction unit may predict whether braking of the vehicle is started based on the 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 with a vehicle in front of the vehicle.

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

It is a schematic diagram which shows an example of schematic structure of the charge system of the vehicle which concerns on embodiment of this invention. It is an explanatory view showing an example of functional composition of a control device concerning the embodiment. It is a flowchart which shows an example of the flow of the 1st process which the control apparatus which concerns on the embodiment performs. It is an explanatory view for explaining change of number of rotations of an expansion machine at the time of braking of vehicles at the time of the 1st processing concerning the embodiment being performed. It is an explanatory view for explaining change of number of rotations of an expansion machine at the time of braking of vehicles at the time of processing concerning a comparative example being performed. It is a flow chart which shows an example of the flow of the 2nd processing which the control device concerning the embodiment performs. It is an explanatory view for explaining change of number of rotations of an expansion machine at the time of braking of vehicles at the time of the 2nd processing concerning the embodiment being performed.

  The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. In the present specification and the drawings, components having substantially the same functional configuration will be assigned the same reference numerals and redundant description will be omitted.

<1. Configuration of charging system>
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 diagram which shows an example of schematic structure of the charging system 10 which concerns on this embodiment. As shown in FIG. 1, the charging system 10 includes an engine 14, a coolant flow passage 16, a driving force transmission system 18, a driving wheel 22, a high voltage battery 30, a motor generator 40, and thermal power generation. The generator 60, the Rankine cycle 70, the external recognition unit 204, the rotation speed sensor 208, the steam pressure sensor 212, and the control device 100 are provided.

  The engine 14 operates or stops in accordance with the traveling state of the vehicle. For example, the engine 14 operates or stops in response to the required torque while the vehicle is traveling. 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. In the cylinder block or cylinder head of the engine 14, a cooling water flow passage 16 through which cooling water circulates is provided to cool the engine 14. The waste heat of the engine 14 is recovered by the cooling water circulating in the cooling water flow passage 16. The cooling water flow path 16 is connected to the heat exchanger 78 of the Rankine cycle 70 outside the engine 14 and exchanges heat 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, 200 V) power supply source. Specifically, the high voltage battery 30 supplies power to the motor generator 40 that outputs the driving force of the vehicle, and also supplies power to the low voltage battery that supplies power to various devices in the vehicle. The electric power generated by the thermal generator 60 and the electric power generated by the motor generator 40 are stored in the high voltage battery 30, respectively.

  The motor generator 40 has a function as a drive motor which generates a drive force of the vehicle. The motor generator 40 is an example of a second generator according to the present invention, and generates electric power using the kinetic energy of the vehicle at the time of braking the vehicle, and stores electric power generated in the high voltage battery 30. It has a function as a generator. The motor generator 40 includes, for example, a three-phase alternating current motor and an inverter device, and is electrically connected to the high voltage battery 30 via the inverter device. The inverter device also has a function as a converter device.

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

  When the motor generator 40 functions as a generator for braking power generation at the time of braking of a vehicle, the inverter device is controlled by the control device 100 so that electric power is generated by the motor using rotational energy of the driving wheel 22 and generated. The AC power is converted into DC power by the inverter device and stored in the high voltage battery 30. As a result, the rotation of the drive wheel 22 is resisted and a braking force is generated. Control device 100 controls the output voltage of motor generator 40 by controlling the inverter device.

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

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

  The Rankine cycle pump 74 is a pump that sucks up the working fluid stored in the tank 98 and circulates the working fluid in the working fluid passage 72. The driving of the Rankine cycle pump 74 is controlled by the controller 100. Specifically, the control device 100 controls the number of rotations of the Rankine cycle pump 74. The Rankine cycle pump 74 is 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 by the cooling water having waste heat of the engine 14 and vaporized.

  The expander 86 expands the working medium vaporized in 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 is expanded in the expansion chamber, and the impeller receives the flow of the working medium, whereby the rotating body connected to the impeller is The energy of the rotational movement is generated. The expander 86 is connected to the thermoelectric generator 60, and mechanical energy generated by the expander 86 is transferred to the thermoelectric generator 60.

  The condenser 90 cools and condenses the working medium in the gas phase that has passed through the expander 86, such as by blowing air from a fan. The working medium condensed by the condenser 90 is stored in the tank 98.

  The bypass flow passage 82 is a flow passage that communicates the upstream side and the downstream side of the working medium flow passage 72 with respect to the expander 86. The bypass flow passage 82 is provided with a bypass valve 94 capable of opening and closing the bypass flow passage 82. In a state where the bypass flow passage 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 order. The drive of the bypass valve 94 is controlled by the controller 100. As the bypass valve 94, for example, a solenoid valve is applied. Note that the bypass valve 94 may be a valve whose opening degree is continuously variable, or may be a valve that can switch only two opening degrees in the open state and the closed state.

  The thermoelectric generator 60 is an example of a first generator according to the present invention. The thermoelectric generator 60 generates electric power using the mechanical energy generated by the expander 86, and stores the generated electric 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. The control device 100 controls the converter device to cause the motor to generate power using the energy of the rotational motion transmitted to the motor, convert the generated AC power into DC power by the converter, and thus the high voltage battery It is stored in 30. 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 imaging elements such as a CCD sensor, a CMOS sensor, etc., captures an image of the external environment outside the vehicle, and displays information indicating the situation in the traveling direction of the vehicle It can be recognized as The external recognition unit 204 outputs, to the control device 100, information indicating the acquired situation of the traveling direction of the vehicle. In addition, when using the information which shows the condition of the advancing direction of the vehicle contained in the information acquired from the outside, such as navigation information, the external recognition part 204 may be abbreviate | omitted from the structure of the charging system 10. FIG.

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

  The vapor pressure sensor 212 is provided on the upstream side of the expander 86 of the working medium channel 72 of the Rankine cycle 70, detects the vapor pressure of the working medium supplied to the expander 86, and outputs a detection result.

  The control device 100 includes a central processing unit (CPU) that is an arithmetic processing unit, a read only memory (ROM) that stores programs used by the CPU, arithmetic parameters, and the like, programs used in the execution of the CPU, and changes appropriately in their execution. It is comprised with RAM (Random Access Memory) etc. which memorize | store temporarily the parameter etc.

  Control device 100 controls the operation of each device constituting charging system 10. Specifically, the control device 100 issues an operation instruction to each actuator to be controlled using an electrical signal. More specifically, control device 100 controls driving of Rankine cycle pump 74, driving of bypass valve 94, output voltage of thermoelectric generator 60, output voltage of motor generator 40, and driving power by motor generator 40. Control generation. Further, the control device 100 receives the information output from each sensor. Control device 100 may communicate with each sensor using CAN (Controller Area Network) communication. In addition, the function which the control apparatus 100 which concerns on this embodiment may be divided | segmented by several control apparatus, In that case, the said several control apparatus may mutually be connected via communication buses, such as CAN. . The details of the control device 100 will be described later.

<2. Controller configuration>
Subsequently, a functional configuration of the control device 100 according to the present embodiment will be described with reference to FIG. FIG. 2 is an explanatory view showing 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.

(Predictor)
The prediction unit 102 predicts whether or not braking of the vehicle is started, and outputs the 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 braking of the vehicle is performed in the near future, and braking of the vehicle is performed in the near future from a state where it is determined that braking of the vehicle is not performed in the near future. It is predicted that braking of the vehicle will be started when the vehicle is switched to the state determined to be turned on. In addition, the determination result in each time about whether braking of a vehicle will be performed by the near future will be memorize | stored in RAM of the control apparatus 100, for example. Further, various setting values used to determine whether or not braking of the vehicle is performed in the near future are stored, for example, in 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. Thereby, 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. The prediction unit 102 predicts whether or not braking of the vehicle is started based on the information indicating the situation of the traveling direction of the vehicle output from the external recognition unit 204, for example. In addition, the prediction unit 102 may predict whether or not braking of the vehicle is started based on the information indicating the situation of the traveling direction of the vehicle included in information acquired from the outside such as navigation information. In the prediction of whether or not the braking of the vehicle is started by the prediction unit 102, the information indicating the shape of the traveling path ahead of the vehicle or the inter-vehicle distance with the vehicle ahead of the vehicle as information indicating the situation in the traveling direction of the vehicle The information which shows can be used.

  The prediction unit 102 may predict whether braking of the vehicle is started based on the shape of the traveling path ahead of the vehicle. Thus, 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 or not braking of the vehicle is started based on, for example, the slope of the traveling path ahead of the vehicle. Specifically, the prediction unit 102 determines that braking of the vehicle will be performed in the near future when the traveling path ahead of the vehicle is a downhill and the gradient is larger than a predetermined gradient at a certain time. . 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 slope is smaller than a predetermined slope, the prediction unit 102 It determines that the vehicle will not be braked in the near future. Here, the predetermined gradient is a threshold value for determining whether or not braking of the vehicle is performed in the near future, and may be set according to the vehicle speed. The prediction unit 102 can predict whether braking of the vehicle is started based on the result determined in this manner.

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

  The prediction unit 102 may predict whether braking of the vehicle is started based on the inter-vehicle distance with the vehicle ahead of the vehicle. Thus, it is possible to appropriately predict whether or not braking of the vehicle is started, taking into consideration the distance between the vehicle and the vehicle ahead of the vehicle. More specifically, when a certain distance between the vehicle and the vehicle ahead of the vehicle is smaller than a predetermined distance and the relative velocity of the vehicle relative to the vehicle ahead is greater than the predetermined velocity, It is determined that the vehicle will be braked in the near future. On the other hand, when the inter-vehicle distance to the vehicle ahead of the vehicle is greater than a predetermined distance at a certain time, or 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 being braked. Here, the predetermined distance and the predetermined speed are thresholds 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 braking of the vehicle is started based on the result determined in this manner.

  Here, in the lane following control, when the inter-vehicle distance from the vehicle ahead of the vehicle becomes smaller than a set reference distance, braking of the vehicle may be automatically started. When a value obtained by subtracting the reference distance in the lane following control from an inter-vehicle distance with a vehicle ahead of the vehicle at a certain time is smaller than a predetermined value, the prediction unit 102 performs braking of the vehicle in the near future. It may be determined that the On the other hand, when a value obtained by subtracting the reference distance in the lane following control from the distance between the vehicle and the vehicle ahead of the vehicle at a certain time is greater 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 braking of the vehicle is performed in the near future, and may be set according to the vehicle speed. The prediction unit 102 can predict whether braking of the vehicle is started based on the result determined in this manner.

  Further, the prediction unit 102 predicts whether or not the braking of the vehicle is ended, 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 where it is determined that braking of the vehicle will be performed in the near future to a state where it is determined that braking of the vehicle is not performed in the near future, braking of the vehicle is ended. Predict. The prediction unit 102 uses the determination result used in the prediction of whether or not the vehicle braking is started as the determination result at each time about whether the vehicle braking is performed in the near future. It can be predicted whether or not

(Pump controller)
The pump control unit 104 controls the driving of the Rankine cycle pump 74. Specifically, the pump control unit 104 controls the number of rotations of the Rankine cycle pump 74. More specifically, the pump control unit 104 controls the number of rotations of the Rankine cycle pump 74 in accordance with the prediction result by the prediction unit 102.

  When the prediction unit 102 predicts that the vehicle is to be braked, the pump control unit 104 reduces the number of rotations of the Rankine cycle pump 74 in accordance with the prediction result of the prediction unit 102. Further, when the prediction unit 102 predicts that the vehicle is to be braked, the pump control unit 104 may increase the number of rotations of the Rankine cycle pump 74 according to the prediction result of the prediction unit 102.

  In the following description, the Rankine cycle pump 74 is based on the predicted result that the braking of the vehicle is ended after the reduction of the rotational speed of the Rankine cycle pump 74 is started based on the predicted result that the braking of the vehicle is started. The control of the driving of the Rankine cycle pump 74 by the pump control unit 104 in a period other than the time period until the increase in the rotational speed of the motor 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 number of revolutions of the Rankine cycle pump 74 based on, for example, the amount of state of the vehicle such as the amount of fuel injection and the number of engine revolutions.

(Bypass valve control unit)
The bypass valve control unit 106 controls the drive 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 setting values used for controlling the drive of the bypass valve 94 by the bypass valve control unit 106 are stored, for example, in the RAM of the control device 100.

  When it is predicted that braking of the vehicle is started, the bypass valve control unit 106 determines that the steam pressure of the working medium supplied to the expander 86 is predetermined if the number of rotations of the expander 86 is higher than a predetermined number of rotations. The bypass valve 94 may be opened if the pressure is higher than

  When it is predicted that braking of the vehicle is started, the bypass valve control unit 106 opens the bypass valve 94 and then opens the bypass valve 94 so that the number of rotations of the expander 86 approaches the target number of rotations. You may control. In addition, when it is predicted that braking of the vehicle is started, the bypass valve control unit 106 opens 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 of the bypass valve 94 may be controlled.

  Further, the bypass valve control unit 106 may close the bypass valve 94 when it is predicted by the prediction unit 102 that the braking of the vehicle is to be ended.

<3. Operation>
Subsequently, a flow of processing performed by the control device 100 according to the present embodiment will be described with reference to FIGS. The process shown in FIG. 3 may be performed constantly after the control system of the vehicle is activated. Hereinafter, an example will be described in which the prediction unit 102 according to the present embodiment outputs a determination flag at each time according to the determination result as to whether or not braking of the vehicle is performed in the near future. The prediction unit 102 outputs “1” as a braking prediction determination flag indicating that braking of the vehicle is determined to 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”. It is predicted that the braking of the vehicle will be terminated.

(Flow of the first process)
FIG. 3 is a flowchart illustrating an example of the flow of the first process performed by the control device 100 according to the present embodiment. FIG. 4 is an explanatory view for explaining the fluctuation of the rotational speed of the expander 86 at the time of braking of the vehicle when the first process 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). If it is not predicted that the braking of the vehicle is to be started by the prediction unit 102 (step S502 / NO), the prediction process of step S502 is repeated. On the other hand, when it is predicted by the prediction unit 102 that braking of the vehicle is started (step S502 / YES), the pump control unit 104 reduces the number of rotations of the Rankine cycle pump 74 (step S504).

  As shown in FIG. 4, when the braking prediction determination flag is switched from "0" to "1" at time T11, it is predicted that the braking of the vehicle is started by the prediction unit 102 (step S502 / YES ). Then, after time T11, the pump control unit 104 reduces the number of revolutions of the Rankine cycle pump 74 (step S504).

  After the process of step S504, as illustrated in FIG. 3, the prediction unit 102 predicts whether or not the braking of the vehicle is ended (step S506). If it is not predicted that the braking of the vehicle is ended by the prediction unit 102 (step S506 / NO), the prediction process of step S506 is repeated. On the other hand, when it is predicted by the prediction unit 102 that the braking of the vehicle is ended (step S506 / YES), the pump control unit 104 performs return processing to the 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 T13, it is predicted that the braking of the vehicle is ended by the prediction unit 102 (step S506 / YES ). Then, after time T13, the pump control unit 104 increases the rotational speed of the Rankine cycle pump 74 to return the Rankine cycle pump 74 to the normal control (Step S508).

  FIG. 5 is an explanatory view 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, in comparison with the present embodiment, prediction of whether or not braking of the vehicle is started and prediction of whether or not 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 vehicle braking is started or the prediction result as to whether or not the vehicle braking is ended. There is no control of the number. In the following description, a comparative example is described in which the rotation speed of the Rankine cycle pump is decreased when braking of the vehicle is actually started, and the rotation speed of the Rankine cycle pump is increased when braking of the vehicle is actually ended. Do.

  In the comparative example, as shown in FIG. 5, the decrease in the rotational speed of the Rankine cycle pump is started at time T91 when braking of the vehicle is actually started. In addition, since braking power generation is performed after time T91, the rotational load of the expander connected to the thermoelectric generator is light. Here, the lower the rotational speed of the Rankine cycle pump, the lower the inflow of the vaporized working medium to the expander, so the amount of energy of the rotational motion generated by the expander can be reduced. However, in the comparative example, the rotation speed of the Rankine cycle pump at time T91 at which the load of the rotation of the expander becomes light is the rotation speed during normal control of the Rankine cycle pump. Therefore, in the period between time T91 and time T92, which is a period immediately after the reduction of the rotation speed of the Rankine cycle pump is started, the rotation speed of the expander may rise sharply. As a result, generation of abnormal noise or seizing of parts may occur. As shown in FIG. 5, in the period from time T91 to time T92, the vapor pressure of the working medium supplied to the expander decreases with the rapid increase in the rotational speed of the expander.

  On the other hand, according to the first process according to the present embodiment, as shown in FIG. 4, at time T11 at which it is predicted that braking of the vehicle is started, reduction of the rotational speed of the Rankine cycle pump 74 is started. Ru. Therefore, the rotation speed of the Rankine cycle pump 74 at time T12 when braking of the vehicle is actually started and braking power generation is started after time T11 has a lower value than the rotation speed at the time of normal control. . Therefore, it is possible to reduce the amount of energy of the rotational motion generated by the expander 86 at time T12 when the load of the rotation of the expander 86 is light. Therefore, it is possible to prevent the rapid increase of the rotational speed of the expander 86. Thereby, generation of abnormal noise and seizing of parts can be prevented.

  Further, in the comparative example, as shown in FIG. 5, at time T93 when the braking of the vehicle is actually ended, the increase in the rotational speed of the Rankine cycle pump is started. After time T93 when braking of the vehicle is actually ended, no braking power generation is performed, so that power can be supplied from the thermoelectric generator to the high voltage battery. Here, as the rotational speed of the Rankine cycle pump is higher, the amount of inflow of the vaporized working medium into the expander is increased, so that the amount of energy of rotational motion generated by the expander can be increased. As a result, the amount of power generation by the thermal power generator can be increased. However, in the comparative example, at time T93 when it is possible to supply power from the generator for thermal power generation to the high voltage battery, the number of revolutions of the Rankine cycle pump is lower than the number of revolutions during normal control. . Therefore, from time T93 to time T94 when the increase in the rotational speed of the Rankine cycle pump ends, the amount of power generation by the thermal power generator is lower than the amount of power generation 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 number of rotations of the Rankine cycle pump 74 is started at time T13 when braking of the vehicle is predicted to end. Ru. Therefore, at time T14 prior to time T15 when braking of the vehicle is actually ended, the number of rotations of the Rankine cycle pump 74 can be increased to the number of rotations at the time of normal control. Therefore, power generation efficiency can be improved after time T15 in which power can be supplied from the thermoelectric generator 60 to the high voltage battery 30.

  When it is predicted that braking of the vehicle is started, the responsiveness of the return to the normal control of the Rankine cycle pump 74 is improved by continuously driving the Rankine cycle pump 74 without stopping it. be able to.

(2nd process 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 view for explaining the fluctuation of the rotational speed of the expander 86 at the time of 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 bypass valve control unit 106 controls the drive of the bypass valve 94. 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 that in the first process. The description of the process of 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 number of rotations of the Rankine cycle pump 74 (step S504), the bypass valve control unit 106 performs expansion. It is determined whether the number of revolutions of the unit 86 is higher than a predetermined number of revolutions N100 (step S702). If the bypass valve control unit 106 determines that the number of rotations of the expander 86 is higher than the predetermined number of rotations N 100 (step S 702 / YES), the bypass valve control unit 106 opens the bypass valve 94 to adjust the opening degree. Degree adjustment control is started (step S704). Specifically, in the opening adjustment control of the bypass valve 94, the bypass valve control unit 106 opens the bypass valve 94 and sets 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 number of rotations of the expander 86 is higher than the predetermined number of rotations N100 (step S702 / NO), the process proceeds to the determination processing of step S506.

  As shown in FIG. 7, the prediction unit 102 predicts that the vehicle is to be braked by switching the braking prediction determination flag from “0” to “1” at time T21 (step S 502 / YES ). Then, after time T21, the pump control unit 104 reduces the rotational speed of the Rankine cycle pump 74 (step S504). Further, at time T21, the bypass valve control unit 106 determines that the number of rotations of the expander 86 is higher than the predetermined number of rotations N100 (step S702 / YES). Then, after time T21, the bypass valve control unit 106 starts the opening 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 number of rotations of the expander 86 approaches the target number of rotations after time T21. Do.

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

  According to the second process related to the present embodiment, the expander 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 portion of the working medium that has been supplied thereto is sent from the upstream side to the downstream side of the expander 86 via the bypass flow passage 82. Therefore, the inflow to the expander 86 of the vaporized working medium can be reduced. As a result, the amount of energy of the rotational motion generated by the expander 86 at time T22 when the load on the rotation of the expander 86 is light can be further reduced. Therefore, the rapid increase of the rotational speed of the expander 86 can be prevented more effectively. As a result, the generation of abnormal noise and the burn-in of parts 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 number of rotations of the expander 86 approaches the target number of rotations after time T21 when the bypass valve 94 is opened. Ru. Here, the target rotational speed is set to a value that can be driven continuously without stopping the Rankine cycle pump 74 when it is predicted that braking of the vehicle is started. As a result, when it is predicted that braking of the vehicle is started, the responsiveness of the return to the normal control of the Rankine cycle pump 74 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 is ended (step S506). If it is not predicted that the braking of the vehicle is ended by the prediction unit 102 (step S506 / NO), the prediction process of step S506 is repeated. On the other hand, when it is predicted by the prediction unit 102 that the braking of the vehicle is ended (step S506 / YES), in the second process according to the present embodiment, the pump control unit 104 performs normal control on the Rankine cycle pump 74. The return process and the closing process of the bypass valve 94 by the bypass valve control unit 106 are performed (step S706), and the process shown in FIG. 6 ends.

  As shown in FIG. 7, the prediction unit 102 predicts that the vehicle braking will be ended by switching the braking prediction determination flag from “1” to “0” at time T23 (step S506 / YES ). Then, after time T23, the pump control unit 104 increases the rotational speed of the Rankine cycle pump 74 to return the Rankine cycle pump 74 to the normal control. Further, in the second process according to the present embodiment, the bypass valve control unit 106 closes the bypass valve 94 at time T23 (step S706).

  According to the second process according to the present embodiment, as shown in FIG. 7, the bypass valve 94 is closed at time T23 when it is predicted that the braking of the vehicle will be ended. 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 flow passage 82 is supplied to the expander 86. Therefore, the inflow to the expander 86 of the vaporized working medium can be increased. Therefore, at the time before time T24 when the braking of the vehicle is actually ended, the amount of energy of the rotational motion generated by the expander 86 can be increased in advance. Therefore, power generation efficiency can be improved after time T24 in which power can be supplied from the thermoelectric generator 60 to the high voltage battery 30.

  In the above, the bypass valve control unit 106 has described the example in which the opening adjustment control of the bypass valve 94 is started when it is determined that the rotation speed of the expander 86 is higher than the predetermined rotation speed N100. The technical scope is not limited to such an example. 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 a predetermined pressure The bypass valve control unit 106 may start the opening adjustment control of the bypass valve 94 when it is determined that the value is higher. It should be noted that the predetermined pressure used in the process of determining whether or not to start the opening adjustment control is the vehicle if the opening adjustment control of the bypass valve 94 is not performed when it is predicted that braking of the vehicle is started. Is set to the vapor pressure of the working medium supplied to the expander 86 in such a case that a sharp rise in the rotational speed of the expander 86 can occur when braking of the vehicle is actually started.

  Further, in the above, in the opening adjustment control of the bypass valve 94, the bypass valve control unit 106 opens the bypass valve 94, and then the opening degree of the bypass valve 94 so that the rotation speed of the expander 86 approaches the target rotation speed. However, 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 the vapor pressure of the working medium supplied to the expander 86 approaches the target pressure. The degree of opening may be controlled. The target rotational speed may be set to a value that can be continuously driven without stopping the Rankine cycle pump 74 when it is predicted that braking of the vehicle is started.

<4. End>
As described above, according to the present embodiment, when the prediction unit 102 predicts that the vehicle is to be braked, the pump control unit 104 performs the Rankine cycle pump according to the prediction result by the prediction unit 102. Reduce the number of revolutions of 74. Thereby, it is possible to reduce the amount of energy of rotational motion generated by the expander 86 at the time when braking of the vehicle is actually started and the rotational load of the expander 86 becomes light. Therefore, it is possible to prevent the rapid increase of the rotational speed of the expander 86. Thereby, generation of abnormal noise and seizing of parts can be prevented.

  Although the driving force generated by the operation of the engine 14 has been described above as being transmitted to the drive wheel 22 via the driving force transmission system 18, the technical scope of 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 may be stored in the high voltage battery 30.

  In the above description, the Rankine cycle 70 has been described as an example of generating mechanical energy by performing heat exchange with cooling water that recovers the waste heat of the engine 14 of the vehicle. The scope 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 of the engine 14 of the vehicle. In such a case, the working medium channel 72 and the exhaust gas pipe can be connected to the heat exchanger 78.

  Further, although the example in which the battery is the high voltage battery 30 has been described above, the technical scope according to the present invention is not limited to such an example. For example, the battery supplies low power to various devices in the vehicle It may be a battery. In such a case, the thermal power generation generator 60 and the motor generator 40 are each electrically connected to the low voltage battery, and the power generated by the thermal power generation generator 60 in thermal power generation and the motor generator 40 in braking power generation. The electric power generated by each may be configured to be stored in the low voltage battery, respectively.

  In addition, the processes described using the flowchart in the present specification may not necessarily be performed in the order shown in the flowchart. Several processing steps may be performed in parallel. Also, additional processing steps may be employed and some processing steps may be omitted.

  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 such examples. It is obvious that those skilled in the art to which the present invention belongs can conceive of various modifications or applications within the scope of the technical idea described in the claims. Of course, it is understood that these also fall within the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Charging system 14 Engine 16 Cooling water flow path 18 Drive power transmission system 22 Drive wheel 30 High voltage battery 40 Motor generator 60 Generator for thermal power generation 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 Controller 102 Predictor 104 Pump controller 106 Bypass valve controller 204 External recognition unit 208 Rotational speed sensor 212 Steam 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 and expanding the working medium to generate mechanical energy;
A first generator that generates power using the mechanical energy generated by the expander and stores the generated power in a battery;
A second generator that generates electric power using kinetic energy of the vehicle at the time of braking the vehicle and stores the generated electric power in the battery;
In a control device of a vehicle provided with
A pump control unit that controls driving of a Rankine cycle pump that circulates the working medium;
A prediction unit that predicts whether or not braking of the vehicle is started;
Equipped with
The pump control unit reduces the number of revolutions of the Rankine cycle pump according to the prediction result by the prediction unit when the prediction unit predicts that the vehicle is to be braked.
Vehicle control device. The Rankine cycle includes a bypass flow passage communicating the upstream side and the downstream side of the flow passage with respect to the expander, and a bypass valve capable of opening and closing the bypass flow passage,
When it is predicted that braking of the vehicle is started, the number of revolutions of the expander is higher than a predetermined number of revolutions, or the vapor pressure of the working medium supplied to the expander is higher than a predetermined pressure And a bypass valve control unit for opening the bypass valve,
The control device of the vehicle according to claim 1.   When it is predicted that the braking of the vehicle is started, the bypass valve control unit opens the bypass valve and then the opening degree of the bypass valve so that the rotation speed of the expander approaches a target rotation speed. The control apparatus of the vehicle of Claim 2 which controls.   When it is predicted that the braking of the vehicle is started, the bypass valve control unit opens the bypass valve, and then the vapor pressure of the working medium supplied to the expander approaches a target pressure. The control device of the vehicle according to claim 2 controlling an opening of said bypass valve. The prediction unit predicts whether or not the braking of the vehicle is ended;
The pump control unit increases the number of revolutions of the Rankine cycle pump according to the prediction result by the prediction unit when the prediction unit predicts that the vehicle is to be braked.
The control apparatus of the vehicle as described in any one of Claims 1-4. The prediction unit predicts whether or not the braking of the vehicle is ended;
The bypass valve control unit closes the bypass valve when it is predicted by the prediction unit that the braking of the vehicle is ended.
The control apparatus of the vehicle as described in any one of Claims 2-4.   The control device for a vehicle 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 control device of a vehicle 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 in front of the vehicle.   The control device for a vehicle according to claim 7, wherein the prediction unit predicts whether or not braking of the vehicle is started based on an inter-vehicle distance with a vehicle in front of the vehicle.

Images