JP2008273289A - Control device of hybrid car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain travelling performance responding to a request of a driver while preventing disturbance in behavior of a vehicle caused by change of a driving system in a hybrid car whose driving system is changed between a two-wheel driving system for driving front wheels by an internal combustion engine and a four-wheel driving system for driving rear wheels by an electric motor while driving the front wheels by the internal combustion engine. <P>SOLUTION: When a request for changing the driving system occurs while the vehicle 11 is turning, whether the behavior of the vehicle 11 changes or not is estimated for the case that the driving system is changed in response to the request for changing the driving system. As a result, the disturbance of the behavior of the vehicle 11 caused by change of the driving system can be prevented by inhibiting the change of the driving system if the change of the behavior of the vehicle 11 is estimated to be present when the driving system is changed. Meanwhile, the change of the driving system is permitted if the disturbance of the behavior of the vehicle 11 is estimated not to occur when the driving system is changed. Thereby the travelling performance responding to the request of the driver can be obtained because torque limitation etc. for preventing the disturbance of the behavior of the vehicle 11 caused by the change of the driving system becomes needless. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hybrid vehicle control device including an internal combustion engine that drives one of a front wheel and a rear wheel of a vehicle and an electric motor that drives the other.

  In recent years, hybrid vehicles equipped with an internal combustion engine and an electric motor as power sources for vehicles have been increasing for the purpose of reducing vehicle fuel consumption and exhaust emissions. Such a hybrid vehicle includes an internal combustion engine that drives the front wheels of the vehicle and an electric motor that drives the rear wheels, as described in Japanese Patent Application Laid-Open No. 2001-180318. The two-wheel drive method for driving the vehicle by driving only the front wheels and the four-wheel drive method for driving the vehicle by driving the front wheels and the rear wheels by the internal combustion engine and the electric motor, respectively, are changed according to the drive method change request. There is something like that.

  However, if the driving method is changed while the vehicle is turning (especially turning on a road surface with a low friction coefficient), the lateral force acting on the wheel changes due to the change in the driving force acting on the wheel (tire). May be disturbed.

Therefore, as described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2006-223073), the target torque with respect to the accelerator opening is made smaller than that during normal traveling during turning while the steering angle of the steering is equal to or greater than a predetermined value. Thus, there is one that suppresses a change in driving force (driving torque) acting on the driving wheel to prevent a disturbance in the behavior of the vehicle.
JP 2001-180318 A Japanese Patent Laying-Open No. 2006-223073 (page 11, FIG. 4, etc.)

  However, in the technique of Patent Document 2 described above, the target torque for the accelerator opening is always made smaller than during normal traveling during a turn with a steering angle equal to or greater than a predetermined value, and therefore, according to the driver's request (accelerator opening). The driving torque cannot be generated, and the running performance (acceleration performance, etc.) according to the driver's request cannot be realized.

  The present invention has been made in consideration of such circumstances, and therefore the object of the present invention is to realize driving performance according to the driver's request while preventing disturbance of the behavior of the vehicle due to the change of the driving system. An object of the present invention is to provide a control device for a hybrid vehicle that can be used.

  In order to achieve the above object, an invention according to claim 1 is provided with an internal combustion engine that drives one of the front wheels and the rear wheels of a vehicle and an electric motor that drives the other, and responds to a drive system change request. In the hybrid vehicle control device that changes the drive method by selecting at least one of the motor and the motor as a power source for running the vehicle, the drive method is changed according to the drive method change request when the drive method change request is generated. The change in the behavior of the vehicle when the vehicle is changed is estimated by the vehicle behavior change estimation means, and whether or not the drive system can be changed is determined by the drive system change availability determination means based on the estimation result.

  In this configuration, when it is estimated that the behavior change of the vehicle is present (or large) when the drive method is changed in response to the drive method change request, the change of the drive method is prohibited and the vehicle is changed by the change of the drive method. Disturbance of the behavior can be prevented in advance. On the other hand, when it is estimated that there is no change (or small) in the behavior of the vehicle when the drive method is changed in response to the drive method change request, the change of the drive method is permitted to cause disturbance of the vehicle behavior. Without changing the driving method. As a result, it is not always necessary to limit the torque to prevent disturbance of the vehicle behavior due to the change of the driving method, and it becomes possible to generate the driving torque according to the driver's request (accelerator opening). The driving performance (acceleration performance, etc.) according to the driver's request can be realized.

  In this case, as in claim 2, the drive system is changed based on the acting force acting on at least one of the front wheels and the rear wheels and the required torque of at least one of the internal combustion engine and the electric motor. In this case, it is preferable to estimate the behavior change of the vehicle. In this way, for the wheels that are driven when the drive system is changed, the change in the lateral force acting on the wheels is estimated from the acting force (driving force, lateral force, friction force) acting on the wheels and the required torque. Thus, the behavior change of the vehicle can be estimated.

  Specifically, as in claim 3, the driving method is changed by comparing the limit driving force obtained from the lateral force and friction force acting on the wheel with the required driving force of the wheel obtained from the required torque. In this case, it is preferable to estimate the change in the behavior of the vehicle.

In general, the driving force Fx, the lateral force Fy, and the maximum frictional force Ff acting on the wheel (tire) satisfy the relationship of the following equation.
Fx 2 + Fy 2 ≦ Ff 2

Therefore, the limit driving force Fx (max), which is the upper limit value of the driving force Fx that does not decrease the lateral force Fy when the driving force Fx is changed in the wheel driven when the driving method is changed, is given by the following equation. Satisfy the relationship.
Fx (max) 2 + Fy2 = Ff2
Using this relationship, the limit driving force Fx (max) can be obtained from the lateral force Fy and the maximum friction force Ff.

  On the other hand, the required driving force TFx can be obtained from the required torque TT at the wheel driven when the driving method is changed. If this required driving force TFx exceeds the limit driving force Fx (max), the lateral force Fy is Therefore, the yaw rate of the vehicle (the rotational angular velocity around the vertical axis passing through the center of gravity) changes, and the behavior of the vehicle changes.

  Therefore, if the limit driving force Fx (max) obtained from the lateral force Fy and the maximum friction force Ff is compared with the required driving force TFx obtained from the required torque TT, the change in behavior of the vehicle when the driving method is changed is obtained. Can be estimated.

  In this case, the lateral force may be calculated based on the vehicle speed (vehicle speed) and the yaw rate, and the frictional force may be calculated based on the ground contact load of the wheel and the road surface friction coefficient.

The lateral force Fy used when determining the limit driving force Fx (max) can be determined by the following equation using the vehicle weight M, the vehicle speed V, and the yaw rate ω for the reason described later.
Fy = M × V × ω

On the other hand, the maximum frictional force Ff used when determining the limit driving force Fx (max) can be determined by the following equation using the wheel ground load W and the road surface friction coefficient μ.
Ff = μ × W

  When obtaining the road surface friction coefficient, the vehicle reference yaw rate is calculated using a predetermined normative model, and the road surface friction coefficient is estimated based on the reference yaw rate and the actual yaw rate. You may make it do. In this way, the road surface friction coefficient can be estimated based on the reference yaw rate and the actual yaw rate while the vehicle is traveling.

  In this case, as in claim 7, the reference model may be set so as to define the relationship between the running data of the vehicle and the yaw rate when the vehicle runs on a road surface having a predetermined reference road surface friction coefficient. In this way, it is possible to calculate the reference yaw rate when traveling on a road surface having a predetermined reference road surface friction coefficient using the reference model.

  Further, as described in claim 8, it is preferable that the travel data uses a vehicle speed (vehicle speed) and a steering angle. In this way, it is possible to calculate the reference yaw rate when the vehicle travels on the road surface having a predetermined reference road surface friction coefficient from the vehicle speed and the steering angle using the reference model.

  Further, as in claim 9, the road surface friction coefficient is calculated from the ratio between the actual yaw rate and the reference yaw rate by using a road surface friction coefficient estimation map that defines the relationship between the ratio between the actual yaw rate and the reference yaw rate and the road surface friction coefficient. It may be calculated. In this way, the road surface friction coefficient can be accurately calculated from the ratio between the actual yaw rate and the reference yaw rate using the road surface friction coefficient estimation map.

  In this case, as in claim 10, the road surface friction coefficient estimation map may be created based on data measured by actually running the vehicle. In this way, it is possible to create a road surface friction coefficient estimation map with high estimation accuracy.

  Alternatively, as described in claim 11, the road surface friction coefficient estimation map may be created based on data calculated using a simulation tool. In this way, a road surface friction coefficient estimation map can be easily created.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of a drive system for a hybrid vehicle that uses an internal combustion engine and an electric motor as drive sources will be described with reference to FIG.

  An engine 13, which is an internal combustion engine that drives the front wheels 12, is disposed on the front side of the vehicle 11, and the output of the engine 13 is transmitted to the axle 15 of the front wheels 12 via the transmission 14. It is designed to be rotated.

  On the other hand, on the rear side of the vehicle 11, an MG 17 (motor generator) that is an electric motor for driving the rear wheel 16 is arranged, and the output of the MG 17 is an axle 20 of the rear wheel 16 via a speed reducer 18, a differential gear 19, and the like. As a result, the rear wheel 16 is rotationally driven.

  The vehicle speed sensor 21 detects the vehicle speed (the speed of the vehicle 11), and the steering angle sensor 22 detects the steering angle of the steering (not shown). Further, the yaw rate sensor 23 detects the yaw rate of the vehicle 11 (rotational angular velocity about the vertical axis passing through the center of gravity). The yaw rate may be detected from the travel information of the navigation system.

  Outputs of these various sensors are input to an electronic control unit (hereinafter referred to as “ECU”) 24. The ECU 24 is mainly composed of a microcomputer, and controls the operation of the engine 13 and the MG 17 by executing various control programs stored in a built-in ROM (storage medium).

  At this time, the ECU 24 normally causes the vehicle 11 to travel by a two-wheel drive method (front wheel drive method) in which only the front wheels 12 are driven by the engine 13. Then, when a predetermined drive system change condition is established and a drive system change request is generated (for example, when acceleration is requested), the front wheel 12 is driven by the engine 13 and the rear wheel 16 is driven by the MG 17. The vehicle 11 is caused to travel by changing to

  As shown in FIG. 2, when the vehicle 11 is turning (particularly turning on a road surface with a low coefficient of friction), the drive method is changed from the two-wheel drive method to the four-wheel drive method in response to a drive method change request. The lateral force Fy acting on the front wheel 12 or the rear wheel 16 may change due to the change in the driving force Fx acting on the front wheel 12 or the rear wheel 16, and the yaw rate ω of the vehicle 11 changes due to the change in the lateral force Fy. Thus, the behavior of the vehicle 11 may be disturbed and the target traveling lane may not be traced.

  As a countermeasure against this, the ECU 24 executes a drive system change enable / disable determination routine in FIG. 4 to be described later, so that when a drive system change request is generated while the vehicle 11 is turning, the drive system is changed according to the drive system change request. Presence or absence of change in behavior of the vehicle 11 when the vehicle is changed from the two-wheel drive method to the four-wheel drive method is estimated. When it is estimated that there is a behavior change of the vehicle 11 when the drive method is changed in response to the drive method change request, the change of the drive method is prohibited and the behavior of the vehicle 11 is disturbed due to the change of the drive method. In advance. On the other hand, when it is estimated that there is no change in the behavior of the vehicle 11 when the drive system is changed according to the drive system change request, the change of the drive system is permitted and the drive system is changed from the two-wheel drive system to the four-wheel drive system. Change to

  Specifically, as shown in FIG. 3, first, the vehicle speed V detected by the vehicle speed sensor 21 and the steering angle θs detected by the steering angle sensor 22 are input to a reference yaw rate calculation unit 25 (reference yaw rate calculation means). Thus, the reference yaw rate calculation unit 25 calculates a reference yaw rate ωb when traveling on a road surface having a predetermined reference road surface friction coefficient from the vehicle speed V and the steering angle θs using a predetermined reference model. Here, the reference model represents the relationship between the running data (vehicle speed V and steering angle θs) of the vehicle 11 and the yaw rate when traveling on a road surface having a reference road surface friction coefficient (for example, a grip road surface having a relatively high road surface friction coefficient). It is a physical formula set as specified.

  Thereafter, the reference yaw rate ωb calculated by the reference yaw rate calculation unit 25 and the actual yaw rate ω detected by the yaw rate sensor 23 are input to the road surface friction coefficient estimation unit 26 (road surface friction coefficient estimation means), and this road surface friction coefficient estimation is performed. The unit 26 calculates the road surface friction coefficient μ corresponding to the ratio (ω / ωb) between the actual yaw rate ω and the reference yaw rate ωb using the road surface friction coefficient estimation map. Here, the road surface friction coefficient estimation map defines the relationship between the ratio (ω / ωb) of the actual yaw rate ω and the reference yaw rate ωb and the road surface friction coefficient μ based on data actually measured by running the vehicle 11. It was created to do. The road surface friction coefficient estimation map may be created based on data calculated using a simulation tool.

  Thereafter, a request MG set based on the road surface friction coefficient μ calculated by the road surface friction coefficient estimating unit 26, the actual yaw rate ω detected by the yaw rate sensor 23, the vehicle speed V detected by the vehicle speed sensor 21, the accelerator opening, and the like. Torque TTr (requested torque of MG 17) is input to the vehicle behavior change estimation unit 27 (vehicle behavior change estimation means), and the vehicle behavior change estimation unit 27 sets the drive method to the two-wheel drive method according to the drive method change request. The presence or absence of a change in behavior of the vehicle 11 when the vehicle is changed to the four-wheel drive method is estimated.

  Here, a method for estimating the presence or absence of a change in the behavior of the vehicle 11 when the drive method is changed from the two-wheel drive method to the four-wheel drive method will be described.

In general, the driving force Fx, the lateral force Fy, and the maximum frictional force Ff acting on the wheel (tire) satisfy the relationship of the following equation.
Fx 2 + Fy 2 ≦ Ff 2

Therefore, when the driving force Fxr is changed in the rear wheel 16 that is driven when the driving method is changed from the two-wheel driving method to the four-wheel driving method, the upper limit value of the driving force Fxr does not decrease the lateral force Fyr. The limit driving force Fxr (max) satisfies the relationship of the following equation.
Fxr (max) 2 + Fyr2 = Ffr2
When the above equation is solved for the limit driving force Fxr (max), the following equation (1) can be obtained.

Using the above equation (1), the limit driving force Fxr (max) of the rear wheel 16 can be obtained from the lateral force Fyr and the maximum friction force Ffr.
On the other hand, the required driving force TFxr of the rear wheel 16 can be obtained from the required MG torque TTr. When the required driving force TFxr exceeds the limit driving force Fxr (max), the lateral force Fyr decreases. ω changes and the behavior of the vehicle 11 changes.

  Therefore, if the limit drive force Fxr (max) obtained from the lateral force Fyr and the maximum friction force Ffr is compared with the required drive force TFxr obtained from the required MG torque TTr, the drive method is changed from the two-wheel drive method to the four-wheel drive method. It can be estimated whether or not the behavior of the vehicle 11 has changed when the vehicle is changed.

Here, the lateral force Fyr used when the limit driving force Fxr (max) is obtained can be obtained by the following equation (2) using the vehicle weight M, the vehicle speed V, and the yaw rate ω.
Fyr = M × V × ω (2)

The reason for this will be described below. The equation of motion in the rotational direction around the vertical axis passing through the center of gravity of the vehicle 11 and the balance of force in the lateral direction can be expressed as follows.
Lf * Fyf-Lr * Fyr = Iz * dω (a)
Fyf + Fyr = M × V2 / R (b)

  Here, Lf is the distance from the center of gravity of the vehicle 11 to the center of the front wheel 12, and Lr is the distance from the center of gravity of the vehicle 11 to the center of the rear wheel 16. Fyf is a lateral force acting on the front wheel 12, and Fyr is a lateral force acting on the rear wheel 16. Iz is the moment of inertia of the vehicle 11, dω is the yaw angular acceleration (change rate of the yaw rate ω), and R is the turning radius of the vehicle 11.

Since the yaw angular acceleration dω = 0 during steady turning of the vehicle 11, the lateral force Fyr acting on the rear wheel 16 with the above formula (a) and the above formula (b) being set as dω = 0 in the above formula (a). If we solve for, we can get
Fyr = M * V2 / R * Lf / (Lf + Lr) = M * V * ω
Thus, the lateral force Fyr can be obtained by the above equation (2) using the vehicle weight M, the vehicle speed V, and the yaw rate ω.

On the other hand, the maximum frictional force Ffr used when determining the limit driving force Fxr (max) can be determined by the following equation (3) using the ground load Wr of the rear wheel 16 and the road surface friction coefficient μ.
Ffr = μ × Wr (3)

  Accordingly, the vehicle behavior change estimation unit 27 first obtains the lateral force Fyr of the rear wheel 16 by the above equation (2) using the vehicle weight M, the vehicle speed V, and the actual yaw rate ω, and also contacts the ground load Wr of the rear wheel 16. And the road surface friction coefficient μ, the maximum frictional force Ffr of the rear wheel 16 is obtained by the above equation (3). Thereafter, the limit driving force Fxr (max) of the rear wheel 16 is obtained by the above equation (1) using the lateral force Fyr and the maximum frictional force Ffr of the rear wheel 16.

Further, the required driving force TFxr of the rear wheel 16 is obtained from the required MG torque TTr using the reduction ratio of the reduction gear 18, the reduction ratio of the differential gear 19, the radius of the rear wheel 16, and the like.
After that, the limit driving force Fxr (max) is compared with the required driving force TFxr, and when the required driving force TFxr exceeds the limiting driving force Fxr (max), the lateral force Fyr decreases. It is estimated that there is a change in the behavior of the vehicle 11 when the drive system is changed from the two-wheel drive system to the four-wheel drive system in response to the change request. On the other hand, when the required driving force TFxr is less than or equal to the limit driving force Fxr (max), the lateral force Fyr does not decrease. Therefore, when the driving method is changed from the two-wheel driving method to the four-wheel driving method according to the driving method change request. It is estimated that there is no change in the behavior of the vehicle 11.

  The estimation result of the behavior change of the vehicle 11 by the vehicle behavior change estimation unit 27 is input to a drive system change possibility determination unit 28 (drive method change possibility determination unit), and the drive method change possibility determination unit 28 estimates the vehicle behavior change. When it is estimated by the part 27 that the behavior of the vehicle 11 is changed, the change of the driving method is prohibited. Thereby, the disturbance of the behavior of the vehicle 11 due to the change of the driving method is prevented in advance. On the other hand, when it is estimated by the vehicle behavior change estimation unit 27 that there is no behavior change of the vehicle 11, the change of the driving method is permitted. As a result, the drive method is changed from the two-wheel drive method to the four-wheel drive method in response to the drive method change request.

  The drive method change permission determination described above is executed by the ECU 24 according to the drive method change permission determination routine of FIG. Hereinafter, the processing content of this drive system change possibility determination routine will be described.

  The drive system change possibility determination routine shown in FIG. 4 is executed at a predetermined cycle while the ECU 24 is powered on. When this routine is started, first, in step 101, it is determined whether or not a drive system change request is generated because a drive system change condition is satisfied. Here, the drive system change condition is satisfied, for example, when an acceleration request is generated in which the change amount (change speed) of the accelerator opening exceeds a predetermined value.

If it is determined in step 101 that a drive system change request has not occurred, this routine is terminated without performing the processing in step 102 and subsequent steps.
Thereafter, when it is determined in step 101 that a drive system change request has occurred, the process proceeds to step 102 where, for example, the steering angle detected by the steering angle sensor 22 determines whether or not the vehicle 11 is turning. Judgment is made based on θs and the like.

  If it is determined in step 102 that the vehicle 11 is not turning, the process proceeds to step 109, where the drive system is allowed to be changed, and the drive system is changed from the two-wheel drive system to the four-wheel drive system.

  On the other hand, when it is determined in step 102 that the vehicle 11 is turning, that is, when a drive method change request is generated during turning, the two-wheel drive is selected according to the drive method change request. The presence or absence of a behavior change of the vehicle 11 when the method is changed to the four-wheel drive method is estimated as follows.

  First, after calculating the reference yaw rate ωb in the case of traveling on the road surface of the reference road surface friction coefficient (for example, a grip road surface having a relatively high road surface friction coefficient) from the vehicle speed V and the steering angle θs using the reference model in step 103. Then, the process proceeds to step 104, where the road surface friction coefficient μ corresponding to the ratio (ω / ωb) between the actual yaw rate ω and the reference yaw rate ωb is calculated with reference to the road surface friction coefficient estimation map.

  Thereafter, the routine proceeds to step 105, where the lateral force Fyr of the rear wheel 16 is obtained by the above equation (2) using the vehicle weight M, the vehicle speed V, and the actual yaw rate ω, and the ground load Wr of the rear wheel 16 and the road surface friction coefficient are obtained. The maximum frictional force Ffr of the rear wheel 16 is obtained by the above equation (3) using μ, and then the lateral force Fyr and the maximum frictional force Ffr of the rear wheel 16 are used to calculate the rear wheel 16 by the above equation (1). Obtain the limit driving force Fxr (max).

  Thereafter, the routine proceeds to step 106, where the required driving force TFxr of the rear wheel 16 is obtained from the required MG torque TTr using the reduction ratio of the reduction gear 18, the reduction ratio of the differential gear 19, the radius of the rear wheel 16, and the like.

  Thereafter, the process proceeds to step 107, and the drive system is changed from the two-wheel drive system to the four-wheel drive system in response to the drive system change request depending on whether or not the required drive force TFxr exceeds the limit drive force Fxr (max). The presence or absence of the behavior change of the vehicle 11 is determined.

  If it is determined in step 107 that the required driving force TFxr exceeds the limit driving force Fxr (max), the lateral force Fyr decreases, so that the driving method is changed to the two-wheel driving method according to the driving method change request. It is estimated that there is a change in the behavior of the vehicle 11 when the vehicle is changed to the four-wheel drive method, and the process proceeds to step 108 to prohibit the change of the drive method. Thereby, the disturbance of the behavior of the vehicle 11 due to the change of the driving method is prevented in advance.

  On the other hand, if it is determined in step 107 that the required driving force TFxr is equal to or less than the limit driving force Fxr (max), the lateral force Fyr does not decrease. When the system is changed from the four-wheel drive system to the four-wheel drive system, it is estimated that the behavior of the vehicle 11 does not change, and the process proceeds to step 109 to allow the drive system to be changed. As a result, the drive method is changed from the two-wheel drive method to the four-wheel drive method in response to the drive method change request.

  In the present embodiment described above, when a drive system change request is generated while the vehicle 11 is turning, the vehicle when the drive system is changed from the two-wheel drive system to the four-wheel drive system according to the drive system change request. The presence or absence of 11 behavioral changes is estimated. As a result, when it is estimated that there is a change in the behavior of the vehicle 11 when the drive method is changed in response to the drive method change request, the change of the drive method is prohibited, so the vehicle 11 due to the change of the drive method. Disturbance of the behavior can be prevented in advance. On the other hand, when it is estimated that there is no change in the behavior of the vehicle 11 when the drive method is changed in response to the drive method change request, the change in the drive method is permitted, so that the behavior of the vehicle 11 is disturbed. Without changing the driving method, the two-wheel driving method can be changed to the four-wheel driving method.

  As a result, even when a drive system change request is generated while the vehicle 11 is turning, the disturbance of the behavior of the vehicle 11 due to the change of the drive system can be prevented, and the target travel path can be traced. Therefore, it is not always necessary to perform torque limitation or the like for preventing the disturbance of the behavior of the vehicle 11 due to the change of the vehicle, and it becomes possible to generate a driving torque according to the driver's request (accelerator opening). The driving performance (acceleration performance, etc.) according to can be realized.

  In the above embodiment, when the required driving force exceeds the limit driving force, it is estimated that there is a change in the behavior of the vehicle and the change of the driving method is prohibited, and when the required driving force is less than the limit driving force, the vehicle It is estimated that there is no change in the behavior, and the change of the drive method is permitted, but the determination method of whether or not the drive method can be changed may be changed as appropriate, for example, the difference between the required drive force and the limit drive force or When the ratio exceeds a predetermined value, it is estimated that the change in the vehicle behavior is large, and the change of the driving method is prohibited. When the difference or ratio between the required driving force and the limit driving force is less than the predetermined value, the vehicle behavior change It is also possible to allow the change of the driving method by estimating that the value is small.

  Further, in the above embodiment, the change in the behavior of the vehicle 11 is estimated by comparing the limit driving force and the required driving force for only the rear wheel 16, but the limit driving force for both the front wheel 12 and the rear wheel 16 respectively. And the required driving force are compared to estimate the behavior change of the vehicle 11, or the limit driving force and the required driving force for only the front wheels 12 are compared to estimate the behavior change of the vehicle 11. May be. At that time, the required driving force of the front wheels 12 can be obtained from the required torque of the engine 13.

  In the above embodiment, the present invention is applied to a system in which the driving method is changed between the two-wheel driving method (front wheel driving method) and the four-wheel driving method. However, the front wheel driving method, the four-wheel driving method, and the rear wheel driving method are applied. The present invention may be applied to a system that changes the driving method between the driving method and a system that changes the driving method between the front wheel driving method and the rear wheel driving method.

  In the above embodiment, the present invention is applied to a system in which the front wheels are driven by the engine and the rear wheels are driven by MG. However, the present invention is applied to a system in which the front wheels are driven by MG and the rear wheels are driven by the engine. You may do it.

1 is a schematic configuration diagram of a hybrid vehicle drive system according to an embodiment of the present invention. It is a figure for demonstrating the behavior change of a vehicle. It is a block diagram which shows roughly the drive system change possibility determination function of ECU. It is a flowchart explaining the flow of a process of a drive system change possibility determination routine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Vehicle, 12 ... Front wheel, 13 ... Engine (internal combustion engine), 16 ... Rear wheel, 17 ... MG (electric motor), 21 ... Vehicle speed sensor, 22 ... Steering angle sensor, 23 ... Yaw rate sensor, 24 ... ECU, 25 ... Reference yaw rate calculation unit (reference yaw rate calculation means), 26... Road surface friction coefficient estimation unit (road surface friction coefficient estimation means), 27... Vehicle behavior change estimation unit (vehicle behavior change estimation means), 28. (Driving method changeability judging means)

Claims (11)

Power that includes an internal combustion engine that drives one of a front wheel and a rear wheel of a vehicle and an electric motor that drives the other, and that causes the vehicle to travel at least one of the internal combustion engine and the electric motor in response to a drive system change request In a hybrid vehicle control device that selects a power source and changes the drive system,
Vehicle behavior change estimation means for estimating a behavior change of a vehicle when the drive method is changed in response to the drive method change request when the drive method change request is generated;
A hybrid vehicle control device comprising: a drive system change enable / disable determining unit that determines whether or not the drive system can be changed based on an estimation result of the vehicle behavior change estimating unit.   The vehicle behavior change estimating means is based on the acting force acting on at least one of the front wheels and the rear wheels and the required torque of at least one of the internal combustion engine and the electric motor. The hybrid vehicle control device according to claim 1, wherein a change in behavior of the vehicle when the vehicle is changed is estimated.   The vehicle behavior change estimating means changes the driving method by comparing a limit driving force obtained from a lateral force and a friction force acting on the wheel and a required driving force of the wheel obtained from the required torque. The hybrid vehicle control device according to claim 2, wherein the behavior change of the vehicle is estimated.   The vehicle behavior change estimating means calculates the lateral force based on a speed and a yaw rate of the vehicle, and calculates the friction force based on a ground contact load and a road surface friction coefficient. Item 4. The hybrid vehicle control device according to Item 3. A reference yaw rate calculating means for calculating a reference yaw rate of the vehicle using a predetermined reference model;
5. The hybrid vehicle control device according to claim 4, further comprising: a road surface friction coefficient estimating unit that estimates the road surface friction coefficient based on a reference yaw rate calculated by the reference yaw rate calculating unit and an actual yaw rate. . Power that includes an internal combustion engine that drives one of a front wheel and a rear wheel of a vehicle and an electric motor that drives the other, and that causes the vehicle to travel at least one of the internal combustion engine and the electric motor in response to a drive system change request In a hybrid vehicle control device that selects a power source and changes the drive system,
A reference yaw rate calculating means for calculating a reference yaw rate of the vehicle using a predetermined reference model;
A hybrid vehicle control device comprising: a road surface friction coefficient estimating unit that estimates a road surface friction coefficient based on the reference yaw rate calculated by the reference yaw rate calculating unit and the actual yaw rate.   7. The hybrid according to claim 5, wherein the reference model is set so as to define a relationship between vehicle travel data and yaw rate when traveling on a road surface having a predetermined reference road surface friction coefficient. 8. Car control device.   The hybrid vehicle control device according to claim 7, wherein the travel data includes a speed and a steering angle of the vehicle.   The road surface friction coefficient estimating means uses a road surface friction coefficient estimation map that defines the relationship between the ratio between the actual yaw rate and the reference yaw rate and the road surface friction coefficient, and calculates the ratio between the actual yaw rate and the reference yaw rate. 9. The hybrid vehicle control device according to claim 5, wherein the road surface friction coefficient is calculated.   The hybrid vehicle control device according to claim 9, wherein the road surface friction coefficient estimation map is created based on data actually measured by running the vehicle.   The hybrid vehicle control device according to claim 9, wherein the road surface friction coefficient estimation map is created based on data calculated using a simulation tool.

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