JP2016193704A - Control device of hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately suppress an increase in temperature in an EV mode and increase frequency in which the EV mode can be set.SOLUTION: When a vehicle travels with a motor serving as a driving power source (step S1), a current value between the motor and a power storage device is integrated at each hour (step S2). An integrated value is changed so as to increase the integrated value of the current value as a vehicle speed is a higher vehicle speed (step S3), or an evaluation function for setting a determination threshold so as to decrease the determination threshold for the integrated value of the current value is evaluated (step S3). When the integrated value changed to a value corresponding to the vehicle speed by the evaluation function exceeds a predetermined threshold, or the integrated value of the current value exceeds the determination threshold set by the evaluation function (step S4), an engine is started up (step S5).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for a hybrid vehicle including an engine and a motor, and more particularly to a control device for a hybrid vehicle capable of traveling only by a motor.

  An example of a hybrid vehicle capable of traveling only by a motor (EV traveling) is described in Patent Document 1. In the vehicle described in Patent Document 1, when the EV travels and the temperature of the motor rises and the temperature exceeds the cooling start temperature, the water pump is activated, and in that state the motor temperature is above the reference temperature. If so, the engine is started and hybrid driving is performed.

JP 2009-40322 A

  Although the temperature of the motor rises by continuing the EV running, the rising tendency of the temperature varies depending on the running state and the like. However, conventionally, there is a possibility that the cooling cannot be performed accurately because the cooling control is not performed in consideration of the running state or the driving state of the motor. Moreover, in the apparatus described in Patent Document 1, since the water pump is activated to start cooling, the motor temperature is detected, and it is determined whether or not the detected temperature is lower than the reference temperature. In spite of the tendency to decrease, it may be determined that the temperature is higher than the reference temperature. For this reason, the frequency of hybrid traveling increases, and the period during which EV traveling can be performed may be shortened.

  The present invention has been made paying attention to the above technical problem, and suppresses the temperature rise of the motor and the equipment related to the motor, and enables EV traveling using only the motor as a driving force source as much as possible. An object of the present invention is to provide a control device for a hybrid vehicle.

  In order to achieve the above object, the present invention includes an engine, a motor, and a power storage device capable of charging the motor and generating electric power generated by the motor, as well as traveling by the driving force of the engine and the motor. In a control device for a hybrid vehicle capable of traveling with the driving force of the vehicle, the current value between the motor and the power storage device when traveling using the motor as a driving force source is integrated over time to increase the vehicle speed. Obtaining an evaluation function for changing the integrated value so as to increase the integrated value of the current value as the vehicle speed, or setting the determination threshold value so as to reduce the determination threshold value for the integrated value of the current value; When the integrated value changed to a value according to the vehicle speed exceeds a predetermined threshold, or the determination threshold set by the evaluation function is set to the current It is characterized in that the integrated value is configured to start the engine if it exceeds.

  According to this invention, when running with the motor as a driving force source, the current value supplied from the power storage device to the motor and the current value generated by the motor and charged into the power storage device are integrated for each time, The integrated value of the current value or a value obtained by changing the integrated value is compared with a predetermined threshold value. The integrated value is changed by the evaluation function, or the threshold value is set by the evaluation function. Specifically, as the vehicle speed increases, the integrated value is increased or the threshold value is set to a smaller value. When the integrated value changed by the evaluation function exceeds a predetermined threshold value, or when the integrated value of the current value exceeds the threshold value set by the evaluation function, the engine is started from a running state using the motor as a drive source. It is changed to the running state. Therefore, the higher the vehicle speed, the easier the engine is started. When the motor is driven at a high vehicle speed as a driving force source, the temperature of the motor and the electric equipment related to the motor is likely to rise, whereas the engine is easy to start. As a result, the restriction of using the motor as the driving force source is reduced, and the frequency of traveling using the motor as the driving force source can be increased.

It is a flowchart for demonstrating an example of the control performed in the Example of this invention. It is a diagram which shows an example of the evaluation function in the Example of this invention. It is a time chart which shows an example of the change of an evaluation function value at the time of performing control by the Example of this invention, and an engine starting request | requirement. It is a diagram which shows the other example of the evaluation function in the Example of this invention. It is a time chart which shows an example of the change of the driving mode at the time of performing control by the Example of this invention, and the output from an electrical storage apparatus. It is a skeleton figure which shows the power train in the hybrid vehicle which can be made into object by the Example of this invention.

  The hybrid vehicle targeted in the embodiment of the present invention is a hybrid vehicle that includes an engine and a motor as driving force sources and can also be driven by the driving force of only the motor. An example of the power train is shown in FIG. It is shown schematically. In FIG. 6, an engine (ENG) 1 and a first motor (MG1) 2 are connected to the power split mechanism 3. The power split mechanism 3 is a mechanism that performs a differential action by three rotating elements. In the example shown in FIG. 6, a planetary gear mechanism is employed. The engine 1 is connected to a first rotating element (for example, the carrier 4) via a spring damper mechanism 5 for reducing torsional vibration. A first motor (first motor / generator: MG1) 2 is connected to a second rotating element (for example, the sun gear 6). The third rotating element (for example, ring gear 7) is an output member, and the output gear 8 is integrated.

  The engine 1 is a multi-cylinder reciprocating engine and is provided with a one-way clutch 10 that prevents reverse rotation of an output shaft (crankshaft) 9 thereof. The one-way clutch 10 is for stopping the reverse rotation of the engine 1 and applying a reaction torque to the carrier 4 when the first motor / generator 2 outputs a torque for running (torque in the negative rotation direction). It is.

  The spring damper mechanism 5 is a damper mechanism having a well-known configuration in which a driving side member to which the torque of the engine 1 is transmitted and a driven side member connected to the carrier 4 are connected by a coil spring arranged in the rotational direction. It is. The first motor / generator 2 is a motor having a power generation function. A part of the power of the engine 1 is transmitted through the power split mechanism 3 and a negative torque accompanying the power generation (torque in a direction to stop rotation). Is transmitted to the sun gear 6 to appropriately control the engine speed.

  A counter driven gear 11 is connected to the output gear 8, and a counter drive gear 12 provided coaxially with the counter driven gear 11 is meshed with a ring gear 14 in the differential gear 13. The drive gear 16 attached to the rotor shaft of the second motor (second motor / generator: MG2) 15 meshes with the counter driven gear 11. That is, the torque of the second motor / generator 15 is configured to be increased or decreased to the torque transmitted from the output gear 8 to the drive wheels 17. The second motor / generator 15 is a motor having a power generation function in the same manner as the first motor / generator 2 described above, and can output either positive or negative torque. Each motor / generator 2, 15 is connected to a power supply unit 18 having an inverter and a power storage device. An electronic control unit (ECU) 19 for controlling the torque of the motor / generators 2 and 15 and the like is provided. The ECU 19 is configured mainly with a microcomputer, and is configured to perform calculations using input data or stored data and output the calculation results as control command signals.

  The hybrid vehicle described above is capable of a mode (HV mode) in which the vehicle travels using the power output from the engine 1 and a mode (EV mode) in which the motor is driven by the electric power of the power supply unit 18. Briefly describing each mode, in the HV mode, the power output from the engine 1 is divided into the first motor / generator 2 and the output gear 8 by the power split mechanism 3. The first motor / generator 2 is controlled so as to function as a generator and applies a reaction torque to the sun gear 6. As a result, the rotational speed of the engine 1 is controlled to a rotational speed with good fuel efficiency. The electric power generated by the first motor / generator 2 is supplied to the second motor / generator 15 so that the second motor / generator 15 functions as a motor, and the motive power converted into electric power by the first motor / generator 2 is Again, convert to mechanical power.

  The EV mode is a travel mode in which the first motor / generator 2 and the second motor / generator 15 are used as driving power sources, and each motor / generator 2, 15 is driven as a motor by the electric power output from the power storage device of the power supply unit 18. The vehicle travels with the output torque. In this case, the rotation of the engine 1 and the carrier 4 connected thereto in the negative rotation direction (the direction opposite to the direction in which the engine 1 rotates steadily) is blocked by the one-way clutch 10, and in this state, the first motor The generator 2 outputs torque in the negative rotation direction. As a result, the ring gear 7 and the output gear 8 integrated therewith rotate in the forward rotation direction. The torque of the first motor / generator 2 is thus output from the output gear 8 and the second motor / generator 15 outputs the torque in the forward rotation direction. The hybrid vehicle travels forward. During braking, the second motor / generator 15 generates power, and the negative torque (torque in a direction to stop rotation) at that time acts as braking torque, and the generated power is charged in the power storage device. In the EV mode, only the second motor / generator 15 may be used as the driving force source.

  In the EV mode, since a large amount of current flows between the motor / generator 15 (or 2) and the power storage device, the temperature of not only the motor / generators 15 and 2 but also electric devices such as the power supply unit 18 and cables tends to increase. . In the control device according to the embodiment of the present invention, in order to suppress damage to the motors 15 and 2 and electrical equipment due to excessively high temperature or a decrease in durability and to enable the EV mode as much as possible, It is comprised so that the control demonstrated below may be performed. FIG. 1 is a flowchart for explaining the control example. First, it is determined whether or not the EV mode is set (step S1). If a negative determination is made in step S1, the process returns without performing any particular control. If the determination is affirmative in step S1, current values for each time are integrated (step S2). In short, this current value is a detected value of the current flowing between the motor / generator 15 (or 2) used for traveling in the EV mode and the power storage device, and the current discharged from the power storage device and Both of the current charged in the power storage device. The integration may be performed for each motor / generator 15 or 2, or may be performed for each cable or electric device through which a current flows. Furthermore, integration for each time can be performed by sequentially adding the product of the current value and the duration of the current value.

  Next, the evaluation function F is set (step S3). The evaluation function F is a numerical process for evaluating or weighting the integrated value based on the traveling state of the hybrid vehicle. For example, the evaluation function F is a process for changing or correcting the integrated value according to the vehicle speed V. And is shown diagrammatically in FIG. In the example shown here, the integrated value is increased as the vehicle speed V is higher, and the resultant value is used as the integrated value (evaluation function value F) for control. The process of increasing the integrated value according to the vehicle speed V may be a process of correcting the integrated value itself, or a process of correcting the current value every moment according to the vehicle speed V.

  It is determined whether the integrated value (evaluation function value F) of the current value thus obtained is greater than a predetermined threshold value α (step S4). The threshold value α is a value determined by experiment or simulation so that the motor generator 15 or 2 is not restricted by the thermal factor (or temperature factor) of the motor / generator 15 or 2 or the electric device. is there. Therefore, for example, a value smaller than a value corresponding to the upper limit temperature determined so as not to cause melting damage or malfunction is adopted.

  If the determination in step S4 is affirmative, that is, if the integrated value (evaluation function value F) is greater than a predetermined threshold value α, control for starting the engine 1 is executed (step S5), and the process returns. When the engine 1 is started, the mode is switched to the HV mode described above, and a part of the torque output from the engine 1 is output from the output gear 8 via the power split mechanism 3, and the first motor / generator 2 is supplied with other torque. Is driven, the first motor / generator 2 generates electric power, and the second motor / generator 15 is driven by the electric power to output a driving torque. In this case, a part of the running torque is transmitted to the drive wheels 17 without being converted into electric power, so that the current flowing between the motor generators 15 and 2 and the power supply unit 18 is greater than that in the EV mode. As a result, the amount of heat generated by each motor / generator 15, 2 and electrical equipment is reduced. Since the motor / generators 15 and 2 and the electric devices are constantly radiating heat and being cooled by a predetermined cooling means (not shown), the temperature rise is reduced or the temperature is lowered by reducing the amount of heat generation. . Therefore, when the condition for setting the EV mode such as the remaining charge (SOC) of the power storage device is sufficiently high and the required drive amount is small, there is no restriction in terms of thermal or temperature. The mode can be set, and as a result, it is possible to increase the frequency of traveling by effectively using the power.

  On the other hand, if the integrated value (evaluation function value F) is determined to be negative in step S4 because it is equal to or less than a predetermined threshold value α, the EV mode is continued (step S6) and the process returns. This is because there is no possibility that the temperatures of the motor / generators 15 and 2 and the electric devices will rise excessively.

  FIG. 3 is an example of a time chart showing a change in the start request of the engine (ENG) 1 when the above control is performed. The vehicle travels in the EV mode, and when the vehicle speed increases, the heat generation amount increases and the vehicle speed increases. By increasing, the above-described evaluation function value F increases. When the evaluation function value F reaches the aforementioned threshold value α (at time t1), the engine start request is switched from OFF to ON, and the engine 1 is started. In the HV mode in which the engine 1 is driven to travel, the amount of current decreases, so the evaluation function value F decreases with time. When the evaluation function value F decreases to another threshold value β that is smaller than the aforementioned threshold value α (at time t2), the engine 1 start request is turned off and the engine 1 is stopped. The other threshold value β is set with a predetermined hysteresis with respect to the threshold value α in order to prevent the start request of the engine 1 from repeatedly changing between OFF and ON (chattering). This is a threshold value for determining stop. Thus, when the engine 1 is stopped, the EV mode is set if other predetermined conditions for the EV mode are satisfied.

  In the embodiment of the present invention, the evaluation function F may be a function that changes the threshold value α for determining the start of the engine 1 according to the vehicle speed when traveling in the EV mode. FIG. 4 shows an example. The threshold value α shown here is maintained at a predetermined value when the vehicle speed V is equal to or lower than a predetermined vehicle speed, and decreases as the vehicle speed increases until the vehicle speed further increases to another predetermined vehicle speed. The vehicle speed exceeding this value is maintained at a constant value smaller than the value at the low vehicle speed. With such an evaluation function, when the vehicle is traveling at a high vehicle speed in the EV mode, the current that flows through the motor / generators 15 and 2 increases, and the threshold value for determining the start of the engine 1 decreases. As a result, in a traveling state in which the temperature tends to rise, the engine 1 is started by determining the rise in temperature before the detected temperature value actually increases. Therefore, when the temperature of the motor / generators 15 and 2 and various electric devices becomes high, the engine 1 is started and the current value is lowered, so that the temperature is prevented from becoming excessively high. In addition, when a predetermined condition for setting the EV mode is satisfied, there is no thermal restriction or restriction in terms of temperature, so that it is possible to immediately switch to the EV mode, and the frequency of setting the EV mode is set. Can be high.

  FIG. 5 is a time chart for explaining the situation, and shows changes in the detected temperature value Ti, the operation mode (EV, HV), and the output Wout from the power storage device. First, a conventional example that does not use an evaluation function will be described. When the vehicle is traveling in the EV mode, the detected temperature value Ti gradually increases, and when the value reaches the upper limit A that is allowed in design (at time t11), the determination to start the engine 1 is established. Therefore, the output Wout from the power storage device is limited (time t12), and the engine 1 is started by outputting a start command signal for the engine 1 (time t13). On the other hand, in the control according to the embodiment of the present invention, the threshold value α corresponding to the vehicle speed V is set, and the value is a value smaller than the upper limit value A for the temperature when converted to temperature. . Accordingly, the determination to start the engine 1 is established at the time t10 when the detected temperature value reaches a temperature lower than the upper limit value A, and the engine 1 is started. This is shown in broken lines in FIG. As a result, an increase in the heat generation amount and temperature is suppressed, so that the output Wout from the power storage device is not particularly limited. That is, when a predetermined condition for setting the EV mode is satisfied, there is no thermal restriction or restriction in terms of temperature, so that it is possible to immediately switch to the EV mode, and the frequency at which the EV mode can be set is set. Can be high.

  In addition, this invention is not limited to the Example mentioned above, It can change suitably in the range of the structure described in the claim.

  DESCRIPTION OF SYMBOLS 1 ... Engine (ENG), 2 ... 1st motor (MG1), 3 ... Power split mechanism, 4 ... 1st rotation element (carrier), 5 ... Spring damper mechanism, 6 ... 2nd rotation element (sun gear), 7 ... 3rd rotation element (ring gear), 8 ... Output gear, 10 ... One-way clutch, 15 ... 2nd motor (2nd motor generator: MG2), 18 ... Power supply part, 19 ... Electronic control unit (ECU).

Claims (1)

Control of a hybrid vehicle comprising an engine, a motor, and a power storage device capable of charging the motor and supplying electric power generated by the motor, and capable of traveling by the driving force of the engine and traveling by the driving force of the motor In the device
The current value between the motor and the power storage device when running with the motor as a driving force source is integrated for each time,
Change the integrated value so as to increase the integrated value of the current value as the vehicle speed increases, or obtain an evaluation function that sets the determination threshold so as to reduce the determination threshold for the integrated value of the current value,
When the integrated value changed to a value according to the vehicle speed by the evaluation function exceeds a predetermined threshold, or when the integrated value of the current value exceeds the determination threshold set by the evaluation function A hybrid vehicle control apparatus configured to start the engine.

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