Start control apparatus

Abstract

A start control apparatus (7) according to the present disclosure, in a vehicle (10) including an engine (1), a starter motor (2), a travel motor (3), and a battery (4), causes the starter motor (2) to start the engine (1) with the power of the battery (4), and comprises: a calculation unit (8) that calculates the maximum output of the battery (4); and a control unit (9) that executes one of a plurality of start controls on the basis of the maximum output upon starting the engine (1). The start control includes normal control (S8), medium output control (S9), and low output control (S10). The execution conditions of the normal control (S8) include the condition that the maximum output exceeds a first threshold (S4). The execution conditions of the low output control (S10) include the condition that the maximum output is equal to or less than a second threshold value (S5) which is lower than the first threshold value. The execution conditions of the medium output control include the condition that the maximum output is equal to or less than the first threshold and exceeds the second threshold (S4, S5).

Description

Start control device

[0001] The present invention relates to a start control device for starting an engine of a hybrid vehicle.

[0002] Hybrid vehicles are known in which the engine is started by a starter motor while the vehicle is running on the driving force of a traction motor. The driving power for the traction motor and the starter motor is supplied from a battery. However, there is a limit to the amount of power that can be simultaneously drawn from the battery. Therefore, for example, the greater the driving power of the starter motor, the less driving power available for the traction motor, which can lead to concerns about a decline in driving performance. Therefore, it has been proposed to reduce the cranking speed of the starter motor to reduce the power consumed by starting the engine (see Patent Document 1).

[0003] Patent No. 7040669

[0004] However, reducing the cranking speed can cause abnormal noise and vibration generated by the engine to tend to remain in the resonant frequency band of the powertrain and vehicle body. This amplifies the abnormal noise and vibration, deteriorating the vehicle's noise and vibration characteristics. Furthermore, increasing the cranking speed to improve the vehicle's noise and vibration characteristics increases the power consumption required to start the engine.

[0005] One of the objects of the present invention, which has been devised in light of the above-mentioned problems, is to provide a starting control device that can improve the running performance and noise and vibration characteristics of a vehicle when starting the engine. However, in addition to this object, another object of the present invention is to achieve effects derived from the respective configurations shown in the "Description of Embodiments" below, which cannot be obtained with conventional techniques.

[0006] The disclosed starting control device can be realized as the following disclosed aspects (application examples) and solves at least part of the above-mentioned problems. Each of the aspects from aspect 2 onwards is an aspect that can be selected as an additional aspect, and each of the aspects from aspect 2 onwards is an aspect that can be omitted. None of the aspects from aspect 2 onwards discloses an aspect or configuration that is essential to the present invention.

[0007] Aspect 1. The disclosed starting control device is for a vehicle equipped with an engine, a starting motor, a traction motor, and a battery, and causes the starting motor to start the engine using power from the battery, and includes a calculation unit that calculates a maximum output of the battery, and a control unit that performs one of a plurality of starting control operations based on the maximum output when starting the engine.

[0008] The start-up control includes normal control in which the torque of the start-up motor is controlled by setting a target rotation speed of the engine to a first rotation speed, and the rate of change of torque from the start of operation of the start-up motor to the torque peak is a first rate of change; medium output control in which the target rotation speed is set to a second rotation speed which is equal to or lower than the first rotation speed, and the rate of change of torque is a second rate of change which is greater than the first rate of change; and low output control in which the torque of the start-up motor is controlled by setting the target rotation speed to a third rotation speed which is smaller than the second rotation speed, and no torque peak is generated.

[0009] Further, the conditions for implementing the normal control include the maximum output exceeding a first threshold, the conditions for implementing the low output control include the maximum output being equal to or less than a second threshold that is lower than the first threshold, and the conditions for implementing the medium output control include the maximum output being equal to or less than the first threshold and exceeding the second threshold.

[0010] Aspect 2. With regard to an aspect including the above aspect 1, it is preferable that the control unit controls the engine speed at the torque peak under the medium power control to be lower than the engine speed at the torque peak under the normal control. Aspect 3. With regard to an aspect including the above aspect 1, it is preferable that the implementation condition of the normal control includes, as an AND condition, that the vehicle speed of the vehicle is lower than a predetermined vehicle speed, and that the implementation condition of the medium power control includes, as an OR condition, that the vehicle speed is equal to or higher than the predetermined vehicle speed.

[0011] Aspect 4. With regard to an aspect including the above-mentioned Aspect 1, it is preferable that the condition for implementing the normal control includes, as an AND condition, that the acceleration of the vehicle is less than a predetermined acceleration, and that the condition for implementing the medium output control includes, as an OR condition, that the acceleration is equal to or greater than the predetermined acceleration. Aspect 5. With regard to an aspect including the above-mentioned Aspect 1, it is preferable that the condition for implementing the normal control includes, as an OR condition, that the deceleration of the vehicle is equal to or greater than a predetermined deceleration, and that the condition for implementing the medium output control includes, as an AND condition, that the deceleration is less than the predetermined deceleration.

[0012] Aspect 6. With regard to aspects including Aspect 1 above, it is preferable that the control unit sets the value of the second rate of change to a larger value as the maximum output during the medium output control decreases. Aspect 7. With regard to aspects including Aspect 1 above, it is preferable that the control unit sets the value of the second rotation speed to a smaller value as the maximum output during the medium output control decreases.

[0013] Aspect 8. In an aspect including Aspect 1 above (e.g., any one of Aspects 1 to 7), it is preferable that the calculation unit calculates an oil temperature of the engine, and the control unit changes the value of the first threshold or the second threshold in accordance with the oil temperature. For example, the higher the oil temperature, the larger the value of the first threshold or the second threshold may be set, and the lower the oil temperature, the smaller the value of the first threshold or the second threshold may be set. Alternatively, the higher the oil temperature, the smaller the value of the first threshold or the second threshold may be set, and the lower the oil temperature, the larger the value of the first threshold or the second threshold may be set.

[0014] The definitions of AND and OR conditions in this case are as follows: When there is one major condition defined as a combination of multiple minor conditions, and the condition for the major condition to be met is "all of the minor conditions must be met," the individual minor conditions are said to be AND conditions (logical product conditions) for the major condition to be met. Also, when there is one major condition defined as a combination of multiple minor conditions, and the condition for the major condition to be met is "any of the minor conditions must be met," the individual minor conditions are said to be OR conditions (logical sum conditions) for the major condition to be met. Note that the above minor conditions can be defined as a combination of multiple more detailed conditions. Therefore, AND and OR conditions can have a nested structure (for example, a structure in which one AND condition contains multiple OR conditions, or a structure in which one OR condition contains multiple AND conditions).

[0015] The disclosed starting control device can improve the vehicle's driving performance and noise and vibration characteristics when starting the engine. For example, when the maximum output is higher than a first threshold, normal control is performed to start the engine smoothly in a short time while maintaining good noise and vibration characteristics. On the other hand, when the maximum output is equal to or lower than a second threshold, low output control is performed to start the engine while sufficiently suppressing cranking power consumption. Furthermore, when the maximum output is equal to or lower than the first threshold but higher than the second threshold, medium output control is performed to start the engine with slightly reduced cranking power consumption and improved noise and vibration characteristics compared to low output control.

[0016] 1 is a block diagram of a vehicle to which a starting control device according to an embodiment is applied.

[0023] FIG. 1 is a diagram for explaining features of engine starting control. (A) to (C) are graphs relating to normal control, where (A) shows changes in generator torque, (B) shows changes in engine speed, and (C) shows changes in battery output. (A) to (C) are graphs relating to medium output control, where (A) shows changes in generator torque, (B) shows changes in engine speed, and (C) shows changes in battery output. (A) to (C) are graphs relating to low output control, where (A) shows changes in generator torque, (B) shows changes in engine speed, and (C) shows changes in battery output. (A) to (D) are graphs for explaining start conditions for starting control. (A) to (C) are graphs showing examples of setting a second rate of change, and (D) to (F) are graphs showing examples of setting a second speed.

[0024] FIG. 1 is a flowchart for explaining the procedure of starting control.

[0017] The disclosed starting control device is applicable to a vehicle equipped with an engine, a starting motor, and a battery, and functions to cause the starting motor to start the engine using power from the battery. The disclosed starting control device is also preferably applicable to a hybrid vehicle (HEV) or a plug-in hybrid vehicle (PHEV), which includes an engine, a starting motor, a traction motor, and a battery.

[0018] A plug-in hybrid vehicle is a hybrid vehicle that can externally charge the battery or externally receive power from the battery. A plug-in hybrid vehicle is provided with a charging port (inlet) for inserting a charging cable that supplies power from an external charging facility and an outlet for external power supply. In the following embodiment, a starting control device applied to a plug-in hybrid vehicle will be described.

[0019] 1 is a block diagram showing the configuration of a vehicle 10 (hybrid vehicle) to which a starting control device 7 according to an embodiment is applied. The vehicle 10 includes an engine 1 and a traction motor 3 as drive sources, a generator 2 as a starter motor for the engine 1 and a power generation device, and a battery 4 as an electricity storage device.

[0020] The engine 1 is an internal combustion engine such as a gasoline engine or a diesel engine. A generator 2 is connected to the drive shaft of the engine 1. The generator 2 is an electric motor / generator that has the functions of cranking and starting the engine 1 using power from a battery 4 and generating electricity using the driving force of the engine 1. The power generated by the generator 2 is used to drive the traction motor 3 and charge the battery 4. A speed change mechanism (not shown) may be installed on the power transmission path connecting the engine 1 and the generator 2.

[0021] The traction motor 3 is an electric motor / generator that has both the function of propelling the vehicle 10 using power from the battery 4 and power generated by the generator 2, and the function of charging the battery 4 with power generated by regeneration. The drive shaft of the traction motor 3 is connected to the drive wheels 6 of the vehicle 10. A speed change mechanism (not shown) may be installed on the power transmission path connecting the traction motor 3 and the drive wheels 6. The battery 4 is a secondary battery connected to the generator 2 and the traction motor 3. The type of battery 4 is not limited to a specific type and includes, for example, a lithium-ion secondary battery, a lead-acid battery, a nickel-metal hydride battery, a sodium-sulfur battery, etc.

[0022] A clutch 5 is interposed in the power transmission path connecting the engine 1 and the traction motor 3. The engine 1 is connected to drive wheels 6 via the clutch 5, and the traction motor 3 is disposed closer to the drive wheels 6 than the clutch 5. The generator 2 is connected closer to the engine 1 than the clutch 5. When the clutch 5 is disengaged (released), the engine 1 and the generator 2 are disconnected from the drive wheels 6, and the traction motor 3 is connected to the drive wheels 6. Therefore, for example, by operating only the traction motor 3 in this state, "EV driving (motor-only driving)" is achieved. In addition, by operating the engine 1 and causing the generator 2 to generate electricity, "series driving" is achieved. Series driving means driving using the driving force of the traction motor 3 while causing the generator 2 to generate electricity using the driving force of the engine 1.

[0023] On the other hand, when the clutch 5 is connected (engaged), the engine 1, the traction motor 3, and the generator 2 are all connected to the drive wheels 6. Therefore, for example, by operating only the engine 1 in this state, "engine running (engine-only running)" is achieved. In addition, by driving the traction motor 3 and the generator 2, "parallel running" is achieved. Both the series running and parallel running described above are also called "hybrid running."

[0024] The starting control device 7 is a computer (electronic control unit, ECU) that has at least the function of controlling the start of the engine 1. The starting control device 7 has a built-in processor (arithmetic processing unit) and memory (storage device). The contents of the control (control program) performed by the starting control device 7 are stored in the memory, and are executed by loading the contents into the processor as appropriate. Note that the vehicle 10 may be equipped with an engine ECU that controls the operating state of the engine 1 and an HEV-ECU that controls the operating state of the powertrain. In this case, the functions of the starting control device 7 may be implemented in the engine ECU or HEV-ECU.

[0025] Various sensors (not shown) are connected to the starting control device 7, and various information detected by the various sensors is input to the starting control device 7. Specific examples of the various sensors include a voltage sensor for the battery 4, a current sensor, a cell temperature sensor, an outside air temperature sensor, an engine rotation speed sensor, a generator rotation speed sensor, an engine torque sensor, a generator torque sensor, a vehicle speed sensor, an acceleration sensor, and a deceleration sensor. Specific examples of the various information include the charge / discharge current and voltage of the battery 4, the cell temperature, the outside air temperature, the engine rotation speed N, the generator rotation speed, the engine torque, the generator torque, the vehicle speed V (the traveling speed of the vehicle 10), the acceleration A (the rate of change of speed in the acceleration direction of the vehicle 10), and the deceleration D (the rate of change of speed in the deceleration direction of the vehicle 10). The acceleration A and the deceleration D may be obtained from the required driving torque and the required driving force calculated by the ECU without using the acceleration sensor and the deceleration sensor.

[0026] [2. Start Control Device] [A. Calculation Unit and Control Unit] The start control device 7 includes a calculation unit 8 and a control unit 9. These elements are shown by conveniently classifying the functions included in the start control device 7, and can be realized by software (programs) or hardware (electronic control circuits). These elements may be integrated into a single piece of software or hardware, or may be distributed across multiple pieces of software and hardware.

[0027] The calculation unit 8 has a function of calculating the maximum output SOP (State Of Power) of the battery 4. Generally, the maximum output SOP means the maximum value of power (chargeable power, dischargeable power) that can be input / output to / from the battery 4 at that time. In this embodiment, the maximum power SOP refers to the maximum power (dischargeable power [kW]) that can be drawn from the battery 4 at that time.

[0028] The maximum output SOP is calculated based on, for example, the operating state of the battery 4 (such as the state of charge SOC, state of health SOH, voltage, current, and battery temperature) and the driving state of the vehicle 10 (such as the driving mode, outside air temperature, vehicle speed V, acceleration A, and deceleration D). The calculation unit 8 also has a function of detecting or calculating the oil temperature of the engine 1. For example, a value detected by an oil temperature sensor may be used as is for the oil temperature of the engine 1, or a value corrected and calculated based on the driving state of the vehicle 10 (such as the driving mode, outside air temperature, vehicle speed V, acceleration A, and deceleration D) may be used.

[0029] FIG. 2 is a diagram illustrating the characteristics of the start control of the engine 1. The start control is a control for starting the engine 1 using the power of the battery 4 with the starter motor (here, the generator 2). When starting the engine 1, the control unit 9 performs one of a plurality of start control operations based on the maximum output SOP calculated by the calculation unit 8. As shown in FIG. 2, the start control in this embodiment includes normal control, medium output control, and low output control. If the maximum output SOP is relatively large, the control unit 9 determines that there is a margin for the maximum output SOP, and performs normal control. If the maximum output SOP is small, the control unit 9 performs medium output control. Furthermore, if the maximum output SOP is even smaller, the control unit 9 determines that there is no margin for the maximum output SOP, and performs low output control.

[0030] The conditions for starting the engine 1 (engine start conditions) are determined by the control unit 9. The control unit 9 determines whether the engine start conditions are met, and if the engine start conditions are met, performs one of a plurality of start controls based on the maximum output SOP. Specific examples of the engine start conditions include well-known conditions. Examples of well-known conditions are shown below. The control unit 9 can determine that the engine start conditions are met based on the following conditions, for example. Each of the following conditions may be an AND condition or an OR condition for meeting the engine start conditions.

[0031] - The maximum output SOP remains below a predetermined value for a predetermined period of time or more. - The driver's requested torque is equal to or greater than a first threshold. - The vehicle speed V is equal to or greater than a first speed. - The accelerator opening is equal to or greater than a first predetermined opening. - The charging rate SOC of the battery 4 is equal to or less than a predetermined charging rate.

[0032] [B. Normal Control] The normal control corresponds to a general control for starting the engine 1. In the normal control, the target rotation speed when cranking the engine 1 is set to the first rotation speed N １ The first rotation speed N １ is set to a value (for example, about 1000 [rpm]) that makes it easy to start the engine 1 in a short time. The generator torque may be controlled according to a preset variation pattern, or may be controlled based on various parameters corresponding to the running state of the vehicle 10. In addition, in normal control, the torque change rate R from the start of operation of the generator 2 to the torque peak is set to a relatively gentle first change rate R １ In this case, the generator torque is calculated using the torque map M １ The torque peak may be set by the maximum point of the generator torque, which is a predetermined reference torque T Ｓ This means that the maximum value exceeds 1 (relatively large maximum value).

[0033] 3A to 3C are graphs showing the changes in generator torque, engine speed N (the speed of the generator 2), and battery output (power consumption during cranking) during normal control. ０ When normal control is started, the torque change rate R becomes R １ The generator torque gradually increases (see FIG. 3A) so that the engine speed N (generator speed) also gradually increases. １ The generator torque reaches its peak.

[0034] Time t １ The engine speed N (generator speed) is the peak speed N Ｐ１ (See Figure 3(B)). The torque peak occurs at the first rotation speed N１ Since the generator 2 is in a high rotation speed range close to t , the power consumption of the generator 2 becomes relatively high, and the battery output increases significantly (see FIG. 3C). ２ When the engine 1 explodes completely at time t ３ The start of engine 1 is completed.

[0035] [C. Medium Output Control] As shown in Figure 2, the medium output control consumes slightly less cranking power than the normal control, but produces slightly worse noise and vibration (NV) at startup than the normal control. In the medium output control, the target rotation speed when cranking the engine 1 is set to the first rotation speed N １ The second rotation speed N ２ (for example, 501 to 1000 [rpm]). The generator torque may be controlled in accordance with a preset variation pattern, or may be controlled based on various parameters corresponding to the running state of the vehicle 10. In addition, in the medium output control, the torque change rate R from the start of operation of the generator 2 to the torque peak is set to a first change rate R １ a second rate of change R ２ At this time, the generator torque is calculated using the torque map M １ Torque map M, which has peak torque at a lower rotational speed than ２ It may be set by

[0036] That is, in the medium output control, the generator torque is controlled so that the generator 2 reaches the torque peak earlier than in the normal control. In other words, the engine speed N at the time of the torque peak in the medium output control (peak speed N Ｐ２ ) is the engine speed N at the peak torque under normal control (peak speed N Ｐ１ The operating state of the generator 2 is controlled so that the voltage Vcc is lower than the voltage Vcc.

[0037] 4A to 4C are graphs showing the changes in generator torque, engine speed N (generator speed), and battery output (cranking power consumption) during medium output control. ０When the medium output control is started, the torque change rate R becomes R ２ (>R １ ) the generator torque increases rapidly (see FIG. 4A), and the generator torque immediately reaches the reference torque T Ｓ At time t ４ The generator torque reaches its peak at time t ０ ~t ４ The time between is time t ０ ~t ２ shorter than the time between

[0038] Time t ４ The engine speed N (generator speed) is the second speed N ２ The peak rotation speed N is a slightly smaller value away from Ｐ２ (<N Ｐ１ ) (see FIG. 4(B)). Also, the second rotation speed N ２ is the first rotation speed N １ Since the torque peak is located in a lower rotational speed range than during normal control, the power consumption of the generator 2 becomes relatively small, and the battery output decreases (see FIG. 4(C)). ５ When the engine 1 explodes completely at time t ６ The start of engine 1 is completed.

[0039] [D. Low Power Control] As shown in Figure 2, the low power control is a control in which the cranking power consumption is less than that of the normal control and the medium power control, and the starting NV is worse than that of the normal control and the medium power control. In the low power control, the target rotation speed when cranking the engine 1 is set to the second rotation speed N ２ a third rotation speed N smaller than ３ (for example, 500 [rpm] or less). The generator torque may be controlled according to a preset variation pattern, or may be controlled based on various parameters corresponding to the running state of the vehicle 10. Furthermore, in the low output control, no torque peak occurs between the start of operation of the generator 2 and the start of the engine 1. In this case, the generator torque is calculated based on a torque map M where no torque peak occurs, for example, using the actual engine speed as an argument. ３It may be set by

[0040] 5A to 5C are graphs showing the changes in generator torque, engine speed N (generator speed), and battery output (cranking power consumption) during low output control. ０ When the low output control is started, the generator torque is reduced to the reference torque T Ｓ , and a low torque state without a torque peak is maintained (see FIG. 5A). ２ a third rotation speed N smaller than ３ As a result, the power consumption of the generator 2 is reduced, and the battery output is reduced more than during the medium output control (see FIG. 5C). ７ When the engine 1 explodes completely at time t ８ The start of engine 1 is completed.

[0041] [E. Implementation Conditions] The control unit 9 selects one of a plurality of starting control modes based on at least the maximum output SOP of the battery 4, and implements the selected starting control mode. When selecting and implementing the starting control mode, only the maximum output SOP may be referenced, or other parameters may also be referenced. For example, in addition to the maximum output SOP, vehicle speed V, acceleration A, deceleration D, etc. may also be referenced.

[0042] 6A is a graph illustrating the relationship between the type of start-up control and the execution conditions when the execution conditions for the start-up control include only the maximum output SOP. In this example, the maximum output SOP is relatively large, and the first threshold P １ If the maximum output SOP exceeds the first threshold P １ A second threshold P ２ If the maximum output SOP is equal to or less than the first threshold P １ The second threshold P ２ If the difference exceeds 0.05, it is determined that there is a slight margin for the maximum output SOP, and medium output control is performed.

[0043] 6B is a graph illustrating the relationship between the type of start-up control and the execution conditions when the execution conditions for the start-up control include a combination of the maximum output SOP and the vehicle speed V. In the normal control, the maximum output SOP is set to a value equal to or greater than the first threshold P １ When the vehicle speed V exceeds the predetermined vehicle speed V １ The medium output control is performed when the maximum output SOP is less than the second threshold P ２ exceeds the first threshold P １ If the maximum output SOP is equal to or less than the second threshold P ２ When the vehicle speed V exceeds the predetermined vehicle speed V １ The low output control is performed when the maximum output SOP is equal to or greater than the second threshold value P ２ This is implemented if:

[0044] 6C is a graph illustrating the relationship between the type of start-up control and the execution conditions when the execution conditions for the start-up control include a combination of the maximum output SOP and the acceleration A. In the normal control, the maximum output SOP is set to a value equal to or greater than the first threshold P １ and the acceleration A exceeds the predetermined acceleration A １ The medium output control is performed when the maximum output SOP is less than the second threshold P ２ exceeds the first threshold P １ If the maximum output SOP is equal to or less than the second threshold P ２ and the acceleration A exceeds the predetermined acceleration A １ The low output control is performed when the maximum output SOP is equal to or greater than the second threshold P ２ This is implemented if:

[0045] 6D is a graph illustrating the relationship between the type of startup control and the execution conditions when the execution conditions for the startup control include a combination of the maximum output SOP and the deceleration D. The deceleration D shown in FIG. 6D is expressed as a positive value (a value with an opposite sign to the acceleration A). In normal control, the maximum output SOP is set to a value equal to or greater than the first threshold P １ or when the deceleration D exceeds the predetermined deceleration D １ or more, and the maximum output SOP is equal to or greater than the second threshold value P ２ The medium output control is performed when the deceleration D exceeds the predetermined deceleration D １and the maximum output SOP is less than the second threshold P ２ and the maximum output SOP exceeds the first threshold P １ The low output control is performed when the maximum output SOP is equal to or less than the second threshold P ２ The low output control is performed when the maximum output SOP is equal to or less than the second threshold P ２ and the deceleration D is equal to or less than the predetermined deceleration D １ In the above cases, normal control may be performed instead of low output control.

[0046] [F. Details of Threshold] The first threshold P １ , second threshold P ２ may be a fixed value set in advance, or may be a variable value set depending on the operating state of the battery 4 and the running state of the vehicle 10. For example, the control unit 9 may set the first threshold value P １ or the second threshold P ２ The value of may be changed.

[0047] For example, the higher the oil temperature, the lower the first threshold value P １ , second threshold P ２ The lower the oil temperature, the higher the first threshold P １ , second threshold P ２ The value of may be set to a small value. This setting corresponds to expanding the implementation range of medium power control and low power control as the oil temperature increases in the graphs shown in Figures 6(A) to (D). When the oil temperature is high, the viscosity of the engine oil decreases, and the frictional resistance of the engine 1 decreases, making it difficult for the NV at startup to deteriorate, thereby reducing the disadvantages of medium power control and low power control. Therefore, with this setting, medium power control and low power control can be implemented without worrying about deterioration of the NV at startup, and cranking power consumption can be reduced.

[0048] In addition, the higher the oil temperature, the lower the first threshold value P １ , second threshold P ２ The lower the oil temperature, the lower the first threshold value P １ , second threshold P ２The value of may be set to a larger value. This setting corresponds to expanding the range in which normal control is performed as the oil temperature increases in the graphs shown in Figures 6(A) to 6(D). When the oil temperature is high, the viscosity of the engine oil decreases, which reduces the frictional resistance of the engine 1 and makes it easier to reduce the power consumption during cranking, thereby reducing the disadvantages of normal control. Therefore, with this setting, normal control can be performed without worrying about an increase in power consumption during cranking, and good NV at startup can be achieved.

[0049] [G. Details of Medium Output Control] The second change rate R, which is the torque change rate R during medium output control, ２ The method for setting the second rate of change R ２ As shown in FIG. 7A, the first rate of change R １ A predetermined value R Ｘ (a fixed value). １ may be a variable value set according to the maximum output SOP. For example, as shown in FIG. 7B, when the maximum output SOP is less than the first threshold P １ If it is less than or equal to the second rate of change R ２ is a predetermined value R Ｘ (>R １ ), and the maximum output SOP is set to the first threshold P １ If it exceeds the second rate of change R ２ The first rate of change R １ It may be set to the same value as

[0050] Second rate of change R ２ The value of P may be set to be smaller as the maximum output SOP is higher and to be larger as the maximum output SOP is lower. For example, as shown in FIG. 7C, １ The second rate of change R ２ The first rate of change R １ The maximum output SOP is set to the same value as the first threshold P １ The smaller the second rate of change R ２ The value of is gradually increased until the maximum output SOP reaches the second threshold P ２ The second rate of change R ２ is a predetermined value R Ｘ In other words, the maximum output SOP is set to the first threshold value P１ to the second threshold P ２ When the second rate of change R ２ The maximum output SOP and the second rate of change R ２ may be associated with each other.

[0051] The second rotation speed N is the target rotation speed during medium output control. ２ The method for setting the second rotation speed N ２ is the first rotation speed N １ A predetermined value N set in advance within the following range Ｘ (fixed value). ２ may be a variable value set according to the maximum output SOP. For example, as shown in FIG. 7E, when the maximum output SOP is less than the first threshold P １ If it is less than or equal to the second rotation speed N ２ to a predetermined value N Ｘ (<N １ ), and the maximum output SOP is set to the first threshold P １ If it exceeds the second rotation speed N ２ First rotation speed N １ It may be set to the same value as

[0052] Second rotation speed N ２ The value of may be set to be larger as the maximum output SOP is higher and smaller as the maximum output SOP is lower. For example, as shown in FIG. 7F, １ The second rotation speed N when ２ First rotation speed N １ The maximum output SOP is set to the same value as the first threshold P １ The smaller the second rotation speed N ２ The value of the maximum output SOP is gradually decreased until the second threshold P ２ The second rotation speed N ２ to a predetermined value N Ｘ In other words, the maximum output SOP is set to the first threshold value P １ to the second threshold P ２ When the rotation speed is reduced to ２ The maximum output SOP and the second rotation speed N ２may be associated with each other.

[0053] 8 is a flowchart illustrating the procedure for starting control of the engine 1. The control shown in this flowchart is repeatedly performed at a predetermined interval while the engine 1 is stopped. Steps S1 to S7 are steps related to selecting the starting control and determining the conditions for performing the starting control, and steps S8 to S10 are steps in which the starting control is performed. Note that this flowchart illustrates an example in which, when selecting and performing the starting control, three factors, namely, vehicle speed V, acceleration A, and deceleration D, in addition to maximum power output SOP, are referenced. However, one or two of vehicle speed V, acceleration A, and deceleration D may also be referenced in addition to maximum power output SOP.

[0054] Step S1 is a step in which the calculation unit 8 calculates the maximum output SOP of the battery 4. The maximum output SOP is calculated based on the operating state of the battery 4 and the running state of the vehicle 10. Step S2 is a step in which the control unit 9 determines whether the engine start condition is met. If the engine start condition is not met, the control for that cycle ends. If the engine start condition is met, the process proceeds to step S3.

[0055] In step S3, the deceleration D of the vehicle 10 is set to a predetermined deceleration D １ If this condition is met, the control unit 9 determines whether the deceleration D is equal to or greater than the predetermined deceleration D. If this condition is met, the process proceeds to step S8, and the engine 1 is started under normal control. １ In the above state, regenerative power due to deceleration is generated by the traction motor 3, and it becomes easier to secure the cranking power consumption required for starting the engine 1. As a result, it is determined that there is no need to perform medium power control or low power control, and normal control is selected and performed. On the other hand, if the condition of step S3 is not met, the process proceeds to step S4.

[0056] In step S4, the maximum output SOP is set to the first threshold value P １ If this condition is met, it is determined that there is a margin for the maximum output SOP, and the process proceeds to step S6. On the other hand, if this condition is not met, the process proceeds to step S5. In step S5, it is determined whether the maximum output SOP exceeds the second threshold value P２ If the condition of step S5 is met, it is determined that there is a slight margin for the maximum output SOP, and the process proceeds to step S9, where the engine 1 is started under medium output control. If the condition of step S5 is not met, it is determined that there is a slight margin for the maximum output SOP, and the process proceeds to step S10, where the engine 1 is started under low output control.

[0057] In step S6, the vehicle speed V of the vehicle 10 is set to a predetermined vehicle speed V １ If the condition of step S6 is met, the process proceeds to step S7. On the other hand, if the condition of step S6 is not met, it is determined that the driving condition is such that the NV at start-up is unlikely to be noticeable to the occupants (a condition in which the NV at start-up is drowned out by the driving noise), and the process proceeds to step S9, where the engine 1 is started under medium output control.

[0058] In step S7, the acceleration A of the vehicle 10 is equal to the predetermined acceleration A １ If the condition of step S7 is met, the process proceeds to step S8, where the engine 1 is started under normal control. On the other hand, if the condition of step S7 is not met, it is determined that the driving condition is such that the NV at start-up is unlikely to be noticeable to the occupants (a condition in which the NV at start-up is drowned out by the acceleration noise), and the process proceeds to step S9, where the engine 1 is started under medium output control.

[0059] [4. Effects] (1) The start control device 7 of this embodiment is for a vehicle 10 equipped with an engine 1, a generator 2 (starting motor), a traction motor 3, and a battery 4, and causes the generator 2 to start the engine 1 using power from the battery 4. This start control device 7 includes a calculation unit 8 that calculates the maximum output SOP of the battery 4, and a control unit 9 that, when starting the engine 1, performs one of a plurality of start control operations based on the maximum output SOP.

[0060] The start control includes a normal control, a medium power control, and a low power control. In the normal control, the target rotation speed of the engine 1 is set to a first rotation speed N １The torque of the generator 2 is controlled as follows: the torque change rate R from the start of operation of the generator 2 to the torque peak is the first change rate R １ The medium output control is a control in which the target rotation speed is set to the first rotation speed N １ The second rotation speed N ２ The torque of the generator 2 is controlled as follows: the torque change rate R is the first change rate R １ A second rate of change R ２ This is the control that results.

[0061] The low output control is performed by setting the target rotation speed to the second rotation speed N ２ a third rotation speed N smaller than ３ The normal control is performed when the maximum output SOP is equal to or greater than the first threshold P １ The condition for implementing the low output control includes when the maximum output SOP exceeds the first threshold P １ A second threshold P ２ The conditions for implementing the medium output control include the maximum output SOP being equal to or less than the first threshold P １ The second threshold P ２ This includes exceeding

[0062] With the above configuration, it is possible to selectively use three types of start control with gradually different cranking power consumption and start-up NV characteristics, thereby improving energy-saving performance related to the start of the engine 1. In addition, it is possible to improve both the running performance and noise and vibration characteristics of the vehicle 10 when starting the engine 1. For example, when the maximum output SOP is greater than the first threshold P １ If the value is higher than the reference value, normal control is performed, and the engine 1 can be started smoothly in a short time while maintaining good noise and vibration characteristics.

[0063] On the other hand, the maximum output SOP is the second threshold P ２ If the maximum output SOP is equal to or less than the first threshold P, low output control is performed, and the engine 1 can be started while sufficiently suppressing the cranking power consumption. Therefore, the engine 1 can be started while preventing a shortage of output from the travel motor 3 and slow acceleration. １ The second threshold P２ When the output power exceeds 100 W, the medium output control is performed, and the engine 1 can be started with improved noise and vibration characteristics compared to the low output control while appropriately suppressing the cranking power consumption.

[0064] (2) In the above-described start control device 7, the engine rotation speed N at the torque peak in the medium output control (peak rotation speed N Ｐ２ ) is the engine speed N at the peak torque under normal control (peak speed N Ｐ１ ) can be controlled to be lower than the normal power consumption. This makes it possible to more reliably reduce the cranking power consumption during medium power control compared to normal control. Therefore, the engine 1 can be started without impairing the driving performance of the vehicle 10.

[0065] (3) The condition for implementing the normal control is that the vehicle speed V is a predetermined vehicle speed V １ The AND condition can include that the vehicle speed V is less than a predetermined vehicle speed V １ The above conditions can be included as an OR condition. As a result, as shown in FIG. 6B , the operating range in which normal control is performed can be narrowed while the operating range in which medium output control is performed can be expanded, and cranking power consumption can be made more likely to be suppressed in the start control of the engine 1. Therefore, the running performance of the vehicle 10 when starting the engine 1 can be improved.

[0066] (4) The condition for carrying out the normal control is that the acceleration A of the vehicle 10 is equal to or exceeds a predetermined acceleration A １ The AND condition can include that the acceleration A is less than the predetermined acceleration A １ The above conditions can be included as an OR condition. As a result, as shown in FIG. 6C , the operating range in which normal control is performed can be narrowed while the operating range in which medium output control is performed can be expanded, and the cranking power consumption can be made to tend to be suppressed in the start control of the engine 1. Therefore, the running performance of the vehicle 10 when starting the engine 1 can be improved.

[0067] (5) The condition for implementing the normal control is that the deceleration D of the vehicle 10 is equal to or greater than the predetermined deceleration D １The OR condition can include that the deceleration D is equal to or greater than the predetermined deceleration D. １ 6D, the operating range in which normal control is performed when regenerative power is generated can be expanded while the operating range in which medium power control is performed can be narrowed, which tends to improve quietness when starting the engine 1. Therefore, the noise and vibration characteristics when starting the engine 1 can be improved.

[0068] (6) As shown in FIG. 7C, for example, the control unit 9 may adjust the second change rate R ２ In this way, by making the slope of the generator torque steeper as the maximum output SOP decreases, the timing of the torque peak can be made earlier, and the power consumed during cranking can be reduced to ensure the power supplied to the traction motor 3. Therefore, the driving performance of the vehicle 10 when the engine 1 is started can be improved.

[0069] (7) As shown in FIG. 7(F), the control unit 9 adjusts the second rotation speed N as the maximum output SOP decreases during the medium output control. ２ In this way, by reducing the engine speed N (generator speed) as the maximum output SOP decreases, it is possible to suppress the power consumed during cranking and ensure the power supplied to the traction motor 3. Therefore, it is possible to improve the driving performance of the vehicle 10 when the engine 1 is started.

[0070] (8) The calculation unit 8 can calculate the oil temperature of the engine 1. The control unit 9 can also calculate the first threshold value P １ or the second threshold P ２ For example, the higher the oil temperature, the higher the first threshold value P １ , second threshold P ２ When the value of the first threshold P is increased, the range of execution of the medium output control and the low output control can be expanded without worrying about the deterioration of the NV at the start, and the cranking power consumption can be reduced. １ , second threshold P ２If the value of is made small, the range in which normal control is performed can be expanded without worrying about an increase in cranking power consumption, and good NV at startup can be achieved.

[0071] [5. Other] The above-described embodiments are merely illustrative and are not intended to exclude various modifications or applications of techniques not explicitly described in the present embodiments. Each configuration of the present embodiments can be modified in various ways without departing from the spirit of the present embodiments. Furthermore, each configuration of the present embodiments can be selected as needed, or can be appropriately combined with various configurations included in known techniques.

[0072] In the above embodiment, the starting control device 7 is applied to a hybrid vehicle, but the application of the starting control device 7 is not limited to hybrid vehicles. The above starting control device 7 can be applied to vehicles equipped with at least an engine, a starting motor, and a battery. In such vehicles, the same effects as those of the above embodiment can be achieved, and the balance between cranking power consumption and startup NV at engine start can be optimized, thereby improving the vehicle's driving performance and noise and vibration characteristics.

[0073] The present invention is applicable to the manufacturing industry of starting control devices that start engines, the manufacturing industry of vehicles equipped with starting control devices, and the manufacturing industry of hybrid vehicles equipped with starting control devices.

[0074] REFERENCE SIGNS LIST 1 Engine 2 Generator (starting motor) 3 Travel motor 4 Battery 5 Clutch 6 Drive wheels 7 Start control device 8 Calculation unit 9 Control unit 10 Vehicle N Engine rotation speed N １ First rotation speed N ２ Second rotation speed N ３ Third rotation speed N Ｘ Predetermined value N Ｐ１ Peak rotation speed N Ｐ２ Peak rotation speed R Torque change rate R １ First rate of change R ２ Second rate of change R Ｘ Predetermined value T Ｓ Reference torque SOP Maximum output P １ First threshold P ２Second threshold V Vehicle speed V １ Predetermined vehicle speed A Acceleration A １ Predetermined acceleration D Deceleration D １ Predetermined deceleration

Claims

1. A start control device for a vehicle equipped with an engine, a starting motor, a traction motor, and a battery, which causes the starting motor to start the engine using power from the battery, comprising: a calculation unit that calculates the maximum output of the battery; and a control unit that performs one of a plurality of start control operations based on the maximum output when starting the engine, wherein the start control operations include: normal control, in which the target rotation speed of the engine is set to a first rotation speed and the torque of the starting motor is controlled so that the rate of change in torque from the start of operation of the starting motor to a torque peak is a first rate of change; medium output control, in which the target rotation speed is set to a second rotation speed that is equal to or lower than the first rotation speed and the torque change rate is a second rate of change that is higher than the first rate of change; and low output control, in which the target rotation speed is set to a third rotation speed that is lower than the second rotation speed and the torque of the starting motor is controlled so that no torque peak occurs; a condition for implementing the normal control includes the maximum output exceeding a first threshold value; and a condition for implementing the low output control includes the maximum output being equal to or lower than a second threshold value that is lower than the first threshold value. A starting control device, wherein the condition for implementing the medium output control includes the maximum output being equal to or less than the first threshold and exceeding the second threshold.

2. A start control device according to claim 1, characterized in that the control unit controls the engine speed at the torque peak during the medium output control to be lower than the engine speed at the torque peak during the normal control.

3. A starting control device as described in claim 1, characterized in that the conditions for implementing the normal control include, as an AND condition, that the vehicle speed of the vehicle is less than a predetermined vehicle speed, and the conditions for implementing the medium output control include, as an OR condition, that the vehicle speed is equal to or greater than the predetermined vehicle speed.

4. A starting control device according to claim 1, wherein the conditions for implementing the normal control include, as an AND condition, that the acceleration of the vehicle is less than a predetermined acceleration, and the conditions for implementing the medium output control include, as an OR condition, that the acceleration is equal to or greater than the predetermined acceleration.

5. A starting control device according to claim 1, wherein the conditions for implementing the normal control include, as an OR condition, that the deceleration of the vehicle is equal to or greater than a predetermined deceleration, and the conditions for implementing the medium output control include, as an AND condition, that the deceleration is less than the predetermined deceleration.

6. A starting control device according to claim 1, characterized in that the control unit sets the value of the second change rate to be larger the lower the maximum output during the medium output control.

7. A starting control device according to claim 1, characterized in that the control unit sets the value of the second rotation speed to a smaller value as the maximum output in the medium output control becomes lower.

8. A start control device as claimed in any one of claims 1 to 7, characterized in that the calculation unit calculates an oil temperature of the engine, and the control unit changes the value of the first threshold value or the second threshold value according to the oil temperature.

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