JP6192191B2 - Engine torque assist device and torque assist method using ISG - Google Patents

Description

  The present invention relates to an engine torque assisting device and a torque assisting method using an ISG (Integrated Starter Generator).

  A technique is known in which a motor generator (ISG) is mechanically coupled to an output shaft of a vehicle engine via a belt and the engine is started by the motor generator. In addition, a technique is known in which the range in which this ISG is used is used not only for starting an engine but also for assisting torque during vehicle travel (Patent Document 1).

JP 2013-241123 A

  One object of the present disclosure is to determine the engine torque using ISG so as to improve fuel consumption.

  One object of the present disclosure is to enable engine torque assistance by ISG effectively in accordance with the state of charge of a battery.

  According to an embodiment of the present disclosure, an engine torque assist device that assists engine torque by ISG is provided. An engine torque assisting device according to an embodiment includes an ISG control unit, a unit that calculates an accelerator opening change amount based on a signal indicating an accelerator opening from an accelerator opening sensor, and a driver from the engine control unit. Means for calculating a driver required torque change amount based on a signal indicating the required torque. The ISG control unit, when the condition of (i) threshold 1 <accelerator opening change amount, or (ii) threshold 2 <driver required torque change amount and threshold 3 <driver required torque is satisfied, The ISG auxiliary torque is generated using the ISG.

  According to an embodiment of the present disclosure, an engine torque assist device that assists engine torque by ISG is provided. An engine torque assist device according to an embodiment includes an ISG control unit. The ISG control unit receives the charge state of the battery that supplies power to the ISG motor, permits engine torque assistance using ISG when threshold 4 <charge state, and engine torque when predetermined value 1 <charge state The use of the battery for purposes other than assistance is permitted, and threshold value 4 <predetermined value 1 is satisfied.

  According to an embodiment of the present disclosure, an engine torque assist device that assists engine torque by ISG is provided. An engine torque assist device according to an embodiment includes an ISG control unit. The ISG control unit receives the charge state of the battery that supplies power to the motor of the ISG, permits engine torque assistance using ISG when the charge state <threshold value 5, and engine torque when the charge state <predetermined value 2 The use of the battery for purposes other than assistance is permitted, and the predetermined value 2 <threshold value 5.

  According to an embodiment of the present disclosure, an engine torque assist device that assists engine torque by ISG is provided. An engine torque assist device according to an embodiment includes an ISG control unit. The ISG control unit has means for determining the ISG auxiliary torque generated by the ISG so that the fuel efficiency is improved by using a fuel efficiency map on the engine speed-torque plane.

  According to an embodiment of the present disclosure, an engine torque assist device that assists engine torque by ISG is provided. An engine torque assist device according to an embodiment includes an ISG control unit. The ISG control unit realizes the driver required torque as the sum of the ISG auxiliary torque and the engine torque generated by using the ISG, and the engine torque is (driver required torque) and (driver required torque-ISG auxiliary torque). Means for determining with a function that adopts the smaller one of the values.

  According to an embodiment of the present disclosure, an engine torque assisting method using ISG is provided. Such a method is based on the step of calculating the accelerator opening change amount based on the signal indicating the accelerator opening from the accelerator opening sensor, and the driver required torque change based on the signal indicating the driver required torque from the engine control unit. Calculating a quantity. The method further includes (i) threshold 1 <accelerator opening change amount, or (ii) threshold 2 <driver required torque change amount and threshold 3 <driver required torque. Generating ISG auxiliary torque using ISG.

  According to an embodiment of the present disclosure, an engine torque assisting method using ISG is provided. This method uses a threshold value 4 and a predetermined value 1 relating to a charging state of a battery that supplies electric power to the motor of the ISG, and permits engine torque assistance using the ISG when the threshold value 4 <the charging state, and the predetermined value 1 < The battery is allowed to be used for purposes other than assisting engine torque in the charged state, and threshold value 4 <predetermined value 1.

  According to an embodiment of the present disclosure, an engine torque assisting method using ISG is provided. This method uses a threshold value 5 and a predetermined value 2 relating to a charging state of a battery that supplies electric power to an ISG motor, and permits engine torque assistance using ISG when the charging state <threshold value 5, and the charging state <predetermined value. In the case of 2, the use of the battery for purposes other than assisting the engine torque is permitted, and the predetermined value 2 <threshold 5

  According to an embodiment of the present disclosure, an engine torque assisting method using ISG is provided. In this method, the ISG auxiliary torque generated by the ISG is determined by using the fuel consumption map on the engine speed-torque plane so that the fuel consumption is improved.

  According to an embodiment of the present disclosure, an engine torque assisting method using ISG is provided. In this method, the driver request torque is realized as the sum of the ISG auxiliary torque and the engine torque generated using the ISG, and the engine torque is calculated by (driver request torque) and (driver request torque-ISG auxiliary torque). It is determined by the function that adopts the smaller one of the values.

It is a schematic diagram showing the basic composition of the engine torque auxiliary device by one embodiment of this indication. It is a schematic diagram showing the basic composition of the engine torque auxiliary device by one embodiment of this indication. 6 is a graph illustrating driver required torque, ISG auxiliary torque, and actual engine torque according to an embodiment of the present disclosure. FIG. 6 is a diagram illustrating a procedure for determining an ISG auxiliary torque according to an embodiment of the present disclosure; It is a figure which shows the fuel consumption map by engine torque-engine speed used when determining ISG auxiliary | assistant torque by one Embodiment of this indication.

  Hereinafter, an embodiment of an engine torque auxiliary device according to the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, the same or similar elements are denoted by the same or similar reference numerals, and redundant description of the same or similar elements may be omitted in the description of each embodiment. Further, the features shown in each embodiment can be applied to other embodiments as long as they do not contradict each other.

  As shown in FIG. 1, in one embodiment, an engine torque assist device mounted on a vehicle includes an engine 10, a starter 12 that starts the engine 10, an ISG (Integrated Starter Generator) 14 that includes a motor generator, and a motor of the ISG 14. The battery 16 (for example, 14V or 48V battery) which supplies electric power to the is included. The ISG 14 is configured to be able to supply ISG auxiliary torque to the output shaft of the engine 10 via the belt 18.

  The engine 10, the starter 12 for starting the engine 10, the mechanical configuration of the ISG 14, the battery 16, and the belt 18 can be used conventionally, and thus will not be described herein. For example, the configuration described in Patent Document 1 can be used.

  As shown in FIG. 2, in one embodiment of the present invention, the engine torque assisting device includes an ISG control unit 50 for controlling the ISG 14 and an engine control unit 52 for controlling the engine 10. The ISG control unit 50 is configured to receive information 54 such as a state of charge (SOC), voltage, battery current, battery temperature, and the like of the battery 16 and monitor the state of the battery 16.

  The engine control unit 52 is configured to electrically communicate with an accelerator pedal (not shown), the engine 10, and the like and receive various information 56 therefrom. The engine control unit 52 receives information 56 such as an accelerator opening degree and an engine speed, and gives information 58 such as a required ignition timing, a required fuel injection amount, a required air amount, etc. to each component of the engine 10 to operate the engine 10. Can be controlled.

  The ISG control unit 50 and the engine control unit 52 may be configured as independent hardware, or may be implemented as separate software on the same hardware.

  The ISG control unit 50 is configured to communicate with the engine control unit 52. The ISG control unit 50 can transmit the amount of ISG auxiliary torque generated by the ISG 14 to the engine control unit 52 (arrow 60). As will be described in detail below, the engine control unit realizes the driver request torque by generating an engine torque having a value obtained by subtracting the ISG auxiliary torque from the driver request torque. On the other hand, the engine control unit 52 can transmit the driver request torque, the accelerator opening, and the engine speed to the ISG control unit 50 (arrow 62). As described in detail below, the ISG control unit 50 can be configured to determine the ISG auxiliary torque using the driver required torque, the accelerator opening, and the engine speed.

  In one embodiment of the present invention, the ISG controller 50 assists engine torque by generating ISG assist torque when the vehicle is required to accelerate rapidly. In general, when the vehicle is accelerated rapidly, the fuel consumption of the engine decreases. In one embodiment of the present invention, in such a case, an auxiliary torque is generated using ISG to mitigate a reduction in fuel consumption. As shown in FIG. 3, when the driver required torque 72 (the outermost envelope of the graph) is given, the triangular portions of the ISG auxiliary torques 72 and 74 (shown by the broken line in FIG. 3), the actual The driver required torque 72 is realized by the sum of the engine torque 74 (shown by the solid line in FIG. 3). Therefore, even when the vehicle is accelerated rapidly, the engine operating point can be determined where fuel efficiency is good.

  The procedure for determining the ISG auxiliary torque in one embodiment of the present invention will be described with reference to the flowchart of FIG.

  In step S100, this flow is started. The illustrated procedure is repeatedly performed at regular time intervals, for example, every 10 ms.

  In step S102, the engine control unit 52 calculates the driver request torque from vehicle conditions such as the accelerator opening, the engine speed, and the vehicle speed. The calculation method of the driver request torque and the information used for the driver request torque are not the subject of the present invention and are not described in detail, but any method can be adopted. The driver required torque calculated by the engine control unit 52 is transmitted to the ISG control unit 50 by CAN communication (independent hardware) or signal transmission (separate software).

  In step S <b> 104, the ISG control unit 50 determines from the driver request torque received from the engine control unit 52 whether or not the vehicle is demanding rapid acceleration. In step S104, whether or not rapid acceleration is required for the vehicle is (i) threshold 1 <accelerator opening change amount, or (ii) threshold 2 <driver required torque change amount and threshold 3 <changer When either of the required torques is satisfied, it is determined that rapid acceleration is required. Condition (i) is determined to be rapid acceleration when the amount of change in the accelerator opening is large. The condition (ii) is determined to be rapid acceleration when the change amount of the driver request torque is large and the driver request torque is large. The threshold value 1 can be set to, for example, 2% / 0.01 s (including a dead band for preventing a fluctuation in determination). The threshold 2 can be set to, for example, 3 Nm / 0.01 s (including a dead band for preventing a fluctuation in determination). The threshold value 3 can be set to, for example, 30 Nm (including a dead zone for preventing a fluctuation in determination). Condition (ii) differs from condition (i) in that it is determined not from the amount of change in the accelerator opening but from the driver's requested torque and its amount of change, so even if there is no change in the accelerator pedal, torque assistance is provided by ISG14. It can be performed. For example, it corresponds to the case where Luke's control to drive the vehicle at a fixed speed set regardless of the driver's operation of the accelerator pedal, or the case where the electric load changes due to the use of an air conditioner, etc. be able to.

  Next, in step S106, it is determined from the state of the battery 16 whether an ISG operation is possible. In step S106, (1) threshold 4 <battery state of charge (SOC) <threshold 5; (2) battery current <threshold 6; and (3) threshold 7 <battery temperature <threshold 8 or any of these conditions. When at least one condition is satisfied, it can be determined that the ISG operation is possible. The threshold value 4 can be set to, for example, 20% (including a dead zone for preventing a fluctuation in determination). The threshold value 5 can be set to, for example, 80% (including a dead band for preventing a fluctuation in determination). The threshold value 6 can be set to, for example, 10A (including a dead zone for preventing a fluctuation in determination). The threshold value 7 can be set to 10 degrees, for example. The threshold value 8 can be set to 70 degrees, for example.

  These conditions (1) to (3) are conditions for protecting the battery 16. The threshold value 4 of the condition (1) is a condition for preventing the battery 16 from rising, and the threshold value 5 is for preventing the life of the battery 16 from being adversely affected by driving the ISG from the overcharged state. It is a condition. Condition (2) is a condition for avoiding using the battery 16 in an overdischarged state. Condition (3) is a condition for avoiding use when the temperature of the battery 16 is too cold or when it is overheated.

  In one embodiment of the present invention, the threshold values 4 and 7 of the above condition are smaller than a lower limit value (predetermined value 1) that gives permission to use the battery 16 for purposes other than assisting engine torque. Moreover, the threshold value 5, threshold value 6, and threshold value 8 of the above conditions are larger than the upper limit value (predetermined value 2) that gives permission to use the battery 16 for purposes other than assisting engine torque. That is, even under conditions that are not normally used for battery protection, the conditions for permitting use of the battery 14 are temporarily relaxed to assist engine torque. The battery 16 is used for purposes other than assisting the engine torque, for example, when the engine is stopped while the vehicle is running, and when restarting by the ISG. Moreover, the predetermined value 1 can be set to 25% (including a dead band for preventing a fluctuation in determination), for example. The predetermined value 2 can be set to, for example, 75% (including a dead zone for preventing a fluctuation in determination).

  In step S106, the condition for permitting use of the battery 16 is temporarily relaxed because the ISG torque assist does not always operate, and thus the adverse effect on the battery is small.

  If the ISG operable condition is not satisfied in step S106, this procedure is terminated.

  If the ISG operable condition is satisfied in step S106, the ISG control torque generated by the ISG 14 is calculated by the ISG control unit 50 in step S108. The ISG auxiliary torque is determined so that the fuel efficiency of the engine is improved when the driver required torque is realized by the sum of the engine and the ISG auxiliary torque, compared to when the driver required torque is realized only by the engine. To do. In one embodiment, a fuel efficiency map based on engine torque-engine speed can be used to determine fuel efficiency.

  FIG. 5 shows a fuel consumption map by engine torque-engine speed. The straight line going up to the right in the figure shows the torque increase at the time of sudden acceleration when the driver-requested torque is realized only by the engine. The broken line in the figure indicates the increase in engine torque when the driver required torque is realized by the sum of the ISG auxiliary torque and the engine torque. In one embodiment, the ISG auxiliary torque is determined so as to use a torque operation region in which fuel efficiency is improved as indicated by a broken line in the figure.

  If the ISG auxiliary torque is calculated in step S108, the ISG control unit 50 transmits the calculated ISG auxiliary torque to the engine control unit 52.

  In step S110, the engine control unit 52 calculates the torque required for the engine 10. In one embodiment, the torque required for the engine 10 is determined by a function (MIN function) that employs the smaller one of (driver required torque) and (driver required torque-ISG auxiliary torque). This is because the engine 10 realizes the required torque obtained by subtracting the ISG auxiliary torque without changing the value of the variable “driver required torque” itself in the engine control unit 52. In general, the variable “driver required torque” may be used for TM control, ESC control, ABS control, 4-wheel drive control, and the like in addition to ISG torque assistance. Changing the value of the variable “Driver Requested Torque” itself will affect these other controls, so use the above MIN function without changing the value of the variable “Driver Requested Torque”. Thus, even when the ISG torque assist is functioning, consistency with other controls can be maintained. Therefore, even when an improvement is made to realize the ISG torque assist function according to the present disclosure on the basis of a conventional engine control section that does not have an ISG torque assist function, the engine control section changes little and the control is changed. Can reduce the risk of errors.

  Next, in step S112, the required ignition timing, the required fuel injection amount, and the required air amount are calculated from the required torque calculated by the engine control unit 52, and the required torque for the engine 10 is realized. Realizing the required torque in the engine 10 is a conventional technique.

  In step S114, this flow ends.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. In addition, all the features in the above-described embodiments are not necessarily implemented. For example, some of the steps in the flowchart shown in FIG. 4 may be omitted, and some of the determination conditions may be omitted.

Claims (4)

An engine torque assist device for assisting engine torque by ISG,
Has an ISG controller,
The ISG control unit
Receives the state of charge of the battery that supplies power to the motor of the ISG, permits engine torque assistance using the ISG when the threshold value 4 <the charge state, and assists engine torque when the predetermined value 1 <the state of charge. An engine torque assisting device that permits the use of the battery for purposes other than the above, and the threshold value 4 <predetermined value 1.
An engine torque assist device for assisting engine torque by ISG,
Has an ISG controller,
The ISG control unit
Receives a charge state of a battery that supplies power to the motor of the ISG, permits engine torque assistance using the ISG when the charge state <threshold value 5, and assists engine torque when the charge state <predetermined value 2 An engine torque assisting device that permits use of the battery for purposes other than the above, and the predetermined value 2 <threshold value 5.
An engine torque assisting method using ISG,
The threshold 4 and the predetermined value 1 relating to the state of charge of the battery that supplies power to the motor of the ISG are used, and when the threshold 4 <the charging state, engine torque assistance using the ISG is permitted, and the predetermined value 1 <the charging Allowing the use of the battery for purposes other than assisting engine torque in the case of a condition, threshold 4 <predetermined value 1;
An engine torque assisting method using ISG,
The threshold value 5 and the predetermined value 2 relating to the charging state of the battery that supplies power to the motor of the ISG are used, and when the charging state <the threshold value 5, engine torque assistance using the ISG is permitted, and the charging state <predetermined value In the case of 2, the use of the battery for the purpose other than assisting the engine torque is permitted, and the predetermined value 2 <threshold value 5.

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