Patent Description:
<CIT> discloses a road surface condition estimating method that estimates a road surface condition from a time-series waveform of tire vibration during traveling.

<CIT> and <CIT> disclose methods for controlling an engine start threshold for a hybrid vehicle based on estimated road noise level. <CIT> discloses a road surface condition estimating method using noise analysis.

The time-series waveform of tire vibration used to estimate an existing road surface condition described in the aforementioned <CIT> includes micro-vibrations due to a disturbance element acting on a wheel (such as mechanical brake operation or wheel slip). This disturbance element makes it difficult to extract a waveform component that truly represents the road surface condition from the time-series waveform, and thus, the estimation accuracy of the road surface condition is lowered.

On the other hand, the present inventors, as a result of diligent study, have led to the development of a control method that estimates a magnitude of a so-called road noise (noise caused by collision or friction between road surface and tires) from the road surface condition, increases an output of an in-vehicle actuator (compressor, fan, engine, etc.) which is the source of noise when the road noise increases, and reduces the discomfort caused by noise to an occupant.

However, as described above, in the existing method of estimating the road surface condition, an error may occur due to the disturbance element acting on the wheel, and an error may also occur in the estimated value of the magnitude of the road noise. If an estimated value with such an error is used, the output of the in-vehicle actuator may be increased even though the magnitude of the road noise is actually small, and thus may cause discomfort due to noise to the occupant.

Therefore, the object of the present invention is to more reliably prevent giving an uncomfortable feeling to the occupant due to a noise accompanying an operation of an in-vehicle actuator.

The above object is achieved by a control method according to claim <NUM> and a control apparatus according to claim <NUM>.

<FIG> is a block diagram explaining a configuration common to series hybrid vehicles (hereinafter, also simply referred to as "vehicle <NUM>") to which the in-vehicle actuator control method (particularly, the engine start/stop permission control method) according to this embodiment is applied.

As shown in <FIG>, the vehicle <NUM> is configured as a so-called series hybrid vehicle including an engine (internal combustion engine) <NUM>, a power generator <NUM>, a battery <NUM>, an electric drive motor <NUM>, a gear <NUM>, a shaft <NUM>, wheels <NUM>, and a controller <NUM>. That is, in the vehicle <NUM>, the power generator <NUM> is driven by the engine <NUM> to charge the battery <NUM> and the battery <NUM> supplies electric power to the drive motor <NUM> for traveling according to a required output Pr. Further, in this embodiment, the in-vehicle actuator to be controlled includes the engine <NUM>, power generator <NUM>, and drive motor <NUM>.

The engine <NUM> is mechanically connected to the power generator <NUM> via a speed increaser (not illustrated), and the power generator <NUM> is connected to the battery <NUM> so that power can be transmitted or received therebetween.

The drive motor <NUM> is mechanically connected to the shaft <NUM> via the gear <NUM>, and the shaft <NUM> is mechanically connected to the wheels <NUM>. The driving force (or regenerative force) of the drive motor <NUM> is transmitted to the wheels <NUM> via the gear <NUM> and shaft <NUM>. Thus, the rotation speed of the wheels <NUM> (that is, the acceleration or deceleration of the vehicle <NUM>) is regulated by the driving force (or regenerative force) of the drive motor <NUM>.

Particularly, in the vehicle <NUM> of this embodiment, in addition to a mechanical brake that brakes the vehicle <NUM> in response to an operation on a brake pedal mounted on the vehicle <NUM>, there is mounted a regenerative brake that obtains braking force by regenerating the drive motor <NUM> according to a decrease amount when a depression amount for an accelerator pedal mounted on the vehicle <NUM> decreases by the mount.

The controller <NUM> is a computer programmed to manage the overall control of the vehicle <NUM> including the processes related to the engine control method as the in-vehicle actuator control method according to this embodiment. More specifically, the controller <NUM> is configured by providing a program, which is for executing the processes constituting the in-vehicle actuator control method, in a hardware configuration consisting of a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input/output interface (I/O interface). Further, the controller <NUM> may be realized by implementing the above program on one piece of computer hardware, or may be realized by distributing and implementing the above program on a plurality of pieces of computer hardware. As a specific example, the function of the controller <NUM> can be realized by various computers such as a battery controller, a vehicle controller, and a motor controller mounted on the vehicle <NUM>.

The controller <NUM> executes the above engine control method using inputs of various parameters received from various unillustrated sensors or other unillustrated controllers. Specifically, as inputs, the controller <NUM> acquires a detected value of the state of charge of the battery <NUM> (SOC: State Of Charge) (hereinafter also referred to as "battery SOC"), a detected value of the rotation speed of the wheels <NUM> (hereinafter also referred to as "wheel speed w"), a detected value of a steering angle with respect to a steering mounted on the vehicle <NUM> (hereinafter also referred to as "steering angle θ"), a detected value of forward/backward G (ratio of the acceleration of the vehicle <NUM> in forward or backward direction to the gravitational acceleration) (hereinafter also referred to as "detected value of forward/backward G"), a flag indicating an operation of a sideslip prevention system (VDC: Vehicle Dynamics Control) (hereinafter also referred to as "VDC start flag fvdc"), a flag indicating an operation of TCS (Traction Control System) (hereinafter also referred to as "TCS operation flag ftcs"), a flag indicating whether ABS (Antilock Brake System) is operating (hereinafter also referred to as "ABS operation flag fabs"), a flag indicating the validity of CAN (Controller Area Network) communication (hereinafter also referred to as "CAN validity flag fcan"), a flag indicating that the mechanical brake mounted on the vehicle <NUM> is being operated (operation on the brake pedal) (hereinafter also referred to as "brake pedal operation flag fb"), an estimated value of the rotation speed of the drive motor <NUM> (hereinafter also referred to as "motor rotation speed Nm"), and an amount of operation on the accelerator pedal mounted on the vehicle <NUM> (hereinafter also referred to as "accelerator opening APO").

Further, in this embodiment, the accelerator opening APO defines the magnitude of the output (mainly the electric power consumed by the traveling of the vehicle <NUM>) required for the vehicle <NUM> (particularly, the drive motor <NUM>). Particularly, in this embodiment, the controller <NUM> executes power running control that requires the drive motor <NUM> to provide a positive driving force when the accelerator opening APO is equal to or greater than a predetermined value, and executes regenerative control that requires the drive motor <NUM> to provide a negative driving force (that is, regenerative braking force) when the accelerator opening APO is less than the predetermined value. That is, if the accelerator opening APO is equal to or greater than the predetermined value, the output required for the vehicle <NUM> is a positive value, and if the accelerator opening APO is less than the predetermined value, the output required for the vehicle <NUM> is a negative value. In the following description, from the viewpoint of simplification of description, the output (positive value or negative value) required for this vehicle <NUM> is referred to as "required output Pr".

<FIG> is a block diagram illustrating the function of the controller <NUM>. As illustrated, the controller <NUM> includes a vehicle speed calculating unit <NUM>, a target driving force calculating unit <NUM>, a road surface determining unit <NUM>, a sound vibration start determining unit <NUM>, a start/stop flag setting unit <NUM>, and a target power generation operating point setting unit <NUM>.

The vehicle speed calculating unit <NUM> calculates the vehicle speed v of the vehicle <NUM> based on the motor rotation speed Nm. The vehicle speed calculating unit <NUM> outputs the calculated vehicle speed v to the target driving force calculating unit <NUM> and the road surface determining unit <NUM>.

The target driving force calculating unit <NUM> calculates the target value of the driving force set in the drive motor <NUM> (hereinafter also referred to as "target motor torque Tmi") based on the vehicle speed v and accelerator opening APO (required output Pr) from the vehicle speed calculating unit <NUM>. The target driving force calculating unit <NUM> outputs the calculated target motor torque Tm to the road surface determining unit <NUM> and the drive motor <NUM> (a motor inverter which is not illustrated in more detail).

The road surface determining unit <NUM> sets the road surface level Le based on the wheel speed w, steering angle θ, detected value of forward/backward G, VDC start flag fvdc, TCS operation flag ftcs, ABS operation flag fabs, CAN validity flag fcan, brake pedal operation flag fb, and accelerator opening APO.

Here, the road surface level Le is a parameter that indexes the state of the background noise of the vehicle <NUM> when the vehicle <NUM> is traveling. Particularly, the road surface level Le is set as a parameter that indexes an estimated value (hereinafter also referred to as "road noise value") that quantifies the degree of road surface roughness calculated based on the wheel speed w (more specifically, an angular acceleration A to be described later) and whether or not the estimation state of the road noise value is the proper estimation state. More specifically, the road surface level Le of this embodiment includes "<NUM>" corresponding to the case where the estimation state of the road noise value is not the proper estimation state and "<NUM>"-"<NUM>" which level the magnitude of the road noise value at each predetermined stage. Particularly, in this embodiment, the magnitude of the road surface level Le is used as an index for estimating whether the background noise of the vehicle <NUM> is relatively large or small. More specifically, when the road surface level Le is "<NUM>"-"<NUM>", the background noise state is estimated to be the low background noise state, and when the road surface level Le is "<NUM>"-"<NUM>", the background noise state is estimated to be the high background noise state.

Hereinafter, the details of the process related to the setting of the road surface level Le by the road surface determining unit <NUM> will be described.

<FIG> is a block diagram illustrating the function of the road surface determining unit <NUM>. As illustrated, the road surface determining unit <NUM> includes an angular acceleration variance value calculating unit <NUM>, a slip determining unit <NUM>, an estimation state determining unit <NUM>, a variance value correcting unit <NUM>, and a road surface level setting unit <NUM>.

The angular acceleration variance value calculating unit <NUM> calculates the variance value of the angular acceleration A of wheels <NUM> (hereinafter also referred to as "angular acceleration variance value var_A") based on the wheel speed w. Specifically, the angular acceleration variance value calculating unit <NUM> obtains the angular acceleration A by calculating a first derivative of the wheel speed w with respect to time. Then, the angular acceleration variance value calculating unit <NUM> samples the angular acceleration A and sets the variance thereof as the angular acceleration variance value var_A. Hereinafter, this variance value is also referred to as "angular acceleration variance value var_A".

Here, the angular acceleration variance value var_A represents the variation of the angular acceleration A, and is a parameter that correlates to the roughness of the traveling road surface of the vehicle <NUM> (road noise value). Therefore, the angular acceleration variance value var_A can be used as an index for estimating the magnitude of the road noise value that determines the road surface level Le. Further, instead of the angular acceleration variance value var_A, an arbitrary statistic that correlates to the variation of the angular acceleration A such as standard deviation and root mean square may be calculated as an estimation index of the road noise value. Then, the angular acceleration variance value calculating unit <NUM> outputs the calculated angular acceleration variance value var_A to the variance value correcting unit <NUM>.

The slip determining unit <NUM> executes the slip determining process using inputs of the vehicle speed v and the detected value of forward/backward G from the vehicle speed calculating unit <NUM>. The slip determining process is a process of setting the slip flag fsl, which indicates that the vehicle <NUM> has slipped (or the slip is predicted), in a specific traveling scene of the vehicle <NUM> (low-speed traveling state immediately after starting from the stopped state of the vehicle). According to the invention, the slip determining process is executed as one of the elements for determining whether or not the estimation state of the road noise value is the proper estimation state. Particularly, the slip determining process is executed from the viewpoint of detecting the occurrence of slip, with respect to which the estimation accuracy of the road noise value based on the angular acceleration variance value var_A decreases, although the vehicle <NUM> has not reached the extent of slipping due to an operation of the above-mentioned TCS or VDC.

<FIG> and <FIG> are flowcharts for explaining the slip determining process. Particularly, <FIG> shows the processing flow related to the input adjustment of forward/backward G, and <FIG> shows the processing flow related to the setting of the slip flag fsl. Further, the processes related to <FIG> and <FIG> can be executed in parallel with each other.

First, in Step S110 as shown in <FIG>, the slip determining unit <NUM> determines whether or not the vehicle <NUM> has stopped. Specifically, the slip determining unit <NUM> counts the time during which the vehicle speed v is <NUM> or substantially <NUM>, and determines that the vehicle <NUM> has stopped when the time reaches a predetermined vehicle stop determining reference time. The slip determining unit <NUM> terminates this routine when the slip determining unit <NUM> determines that the vehicle <NUM> has not stopped. On the other hand, the slip determining unit <NUM> executes the processes from Step S120 when the slip determining unit <NUM> determines that the vehicle <NUM> has stopped.

In Step S120, the slip determining unit <NUM> executes a zero-point adjustment on the detected value of forward/backward G. That is, the slip determining unit <NUM> calculates the difference obtained by subtracting <NUM> from the detected value of forward/backward G which has been acquired during the stop of the vehicle <NUM>, and stores the difference in a storage region. Then, the slip determining unit <NUM> acquires the value obtained by subtracting the above difference from the detected value input from the G sensor (for example, strain gauge type or capacitance type), which is not illustrated at the subsequent control timing, as the detected value of forward/backward G.

In Step S130 as shown in <FIG>, the slip determining unit <NUM> determines whether or not the vehicle <NUM> is in the low-speed traveling state. Specifically, the slip determining unit <NUM> determines whether or not the vehicle speed v is equal to or less than a predetermined low speed determining threshold value.

Then, when the slip determining unit <NUM> determines that the vehicle <NUM> is not in the low-speed traveling state, the slip determining unit <NUM> sets the slip flag fsl to "<NUM>" and terminates this routine. On the other hand, when the slip determining unit <NUM> determines that the vehicle <NUM> is in the low-speed traveling state, it executes the processes from Step S140.

In Step S140, the slip determining unit <NUM> calculates the estimated value of forward/backward G based on the vehicle speed v. Specifically, the slip determining unit <NUM> calculates the acceleration a by time-differentiating the vehicle speed v, and calculates the estimated value of forward/backward G based on the acceleration a.

Then, in Step S150, the slip determining unit <NUM> determines whether or not the difference between the detected value of forward/backward G calibrated by the value of the stopped state of the vehicle and the estimated value of forward/backward G calculated based on the vehicle speed v is larger than a predetermined reference value. Here, the predetermined reference value is set to a suitable value from the viewpoint of whether the estimated value of forward/backward G estimated from the vehicle speed v (corresponding to the actual rotation speed of the wheels <NUM>) deviates from the detected value of forward/backward G, which is based on the inertial force actually acting on the vehicle <NUM>, to the extent that an occurrence of a slip of the vehicle <NUM> can be determined.

<FIG> is a diagram explaining the interrelation among the detected value of forward/backward G, the estimated value of forward/backward G, and the slip of the vehicle <NUM>. Further, in the graph of <FIG>, the horizontal axis indicates the estimated value of forward/backward G (corresponding to the time derivative value of the motor rotation speed Nm), and the vertical axis indicates the detected value of forward/backward G. In addition, the broken line L1 and the solid line L2 represent the relation between the estimated value of forward/backward G and the detected value of forward/backward G when no slip occurs and when a slip occurs, respectively. Further, the dotted line L3 represents a straight line in which the estimated value of forward/backward G and the detected value of forward/backward G are mutually the same.

As can be seen from <FIG>, the estimated value of forward/backward G and the detected value of forward/backward G are equal to each other when no slip occurs (broken line L1). On the other hand, when a slip occurs, the rate of change in the rotation speed of the wheels <NUM> (the rate of change in the motor rotation speed Nm) deviates from the value assuming that the grip state of the tire and the road surface is maintained. Therefore, when a slip occurs, the estimated value of forward/backward G (solid line L2) determined based on the vehicle speed v calculated from the motor rotation speed Nm deviates from the detected value of forward/backward G detected by a G sensor (a value detected regardless of the motor rotation speed Nm). Therefore, a slip of the vehicle <NUM> can be suitably detected by referring to the mutual deviation between the estimated value of forward/backward G and the detected value of forward/backward G as described in <FIG>.

Then, the slip determining unit <NUM> sets the slip flag fsl of the vehicle <NUM> to "<NUM>" when the determination result of Step S150 is positive. On the other hand, the slip determining unit <NUM> sets the slip flag fsl of the vehicle <NUM> to "<NUM>" when the determination result of Step S150 is negative.

Returning to <FIG>, the slip determining unit <NUM> outputs the set slip flag fsl to the estimation state determining unit <NUM>.

The estimation state determining unit <NUM> executes the estimation state determining process to determine whether or not the estimation state of the road noise value is the proper estimation state using the inputs of the wheel speed w, vehicle speed v, target motor torque Tm, brake pedal operation flag fb, accelerator opening APO, VDC start flag fvdc, TCS operation flag ftcs, ABS operation flag fabs, CAN validity flag fcan, and slip flag fsl. Particularly, in the estimation state determining process of this embodiment, the proper estimation flag fop is set to "<NUM>" when the estimation state of the road noise value is the proper estimation state, and the proper estimation flag fop is set to "<NUM>" when the estimation state of the road noise value is not the proper estimation state. The details of the estimation state determining process will be described below.

<FIG> is a flowchart explaining the estimation state determining process.

As illustrated, first, in Step S200, the estimation state determining unit <NUM> determines whether all of the brake pedal operation flag fb, accelerator off flag fac, VDC start flag fvdc, TCS operation flag ftcs, and ABS operation flag fabs are set to "<NUM>". Further, the accelerator off flag fac is a flag set to "<NUM>" when it is determined that no operation on the accelerator pedal (driving force request for the vehicle <NUM>) has been performed. Specifically, the estimation state determining unit <NUM> sets the accelerator off flag fac to "<NUM>" when the accelerator opening APO is equal to or less than a predetermined value, and "<NUM>" when the accelerator opening APO exceeds the predetermined value.

Then, when the estimation state determining unit <NUM> determines that at least one of these flag values is "<NUM>", it proceeds to Step S270, sets the proper estimation flag fop to "<NUM>", and terminates this routine. That is, when it falls under any of the case where an operation on the brake pedal is detected, the case where no operation on the accelerator pedal is detected, the case where VDC is operating, the case where TCS is operating, and the case where ABS is operating, since it is assumed that the calculated value of the angular acceleration A includes an error, it is determined that the estimation state of the road noise value is not proper.

On the other hand, when the estimation state determining unit <NUM> determines that all the flag values are "<NUM>" in the determination of Step S200, the process of Step S210 is executed.

In Step S210, the estimation state determining unit <NUM> determines whether or not the target motor torque Tm is equal to or greater than the first torque threshold value Tm_th1 and equal to or less than the second torque threshold value Tm_th2. Then, if the result of the determination is negative, the estimation state determining unit <NUM> proceeds to Step S270, sets the proper estimation flag fop to "<NUM>", and terminates this routine. On the other hand, the estimation state determining unit <NUM> executes the process of Step S220 if the result of the determination is positive.

Here, the first torque threshold value Tm_th1 and the second torque threshold value Tm_th2 are the lower limit value and the upper limit value of the target motor torque Tm determined from the viewpoint of ensuring the estimation accuracy of the road noise value, respectively. Further, the first torque threshold value Tm_th1 and the second torque threshold value Tm_th2 may be set to fixed values that are experimentally determined in advance, or may be set to variable values that change according to the traveling state, etc. of the vehicle <NUM>.

Particularly, the first torque threshold value Tm_th1 and the second torque threshold value Tm_th2 may be set to variable values according to the vehicle speed v. Further, for example, when the determination result of Step S210 is negative at a certain control timing, a different first torque threshold value Tm_th1 or second torque threshold value Tm_th2 may be used in such a determination at a later control timing. That is, a predetermined hysteresis may be set for the first torque threshold value Tm_th1 and the second torque threshold value Tm_th2.

Next, in Step S220, the estimation state determining unit <NUM> determines whether or not the vehicle speed v is equal to or greater than the first vehicle speed threshold value v_th1 and equal to or less than the second vehicle speed threshold value v_th2. Then, if the result of the determination is negative, the estimation state determining unit <NUM> proceeds to Step S270, sets the proper estimation flag fop to "<NUM>", and terminates this routine. On the other hand, the estimation state determining unit <NUM> executes the process of Step S230 if the result of the determination is positive.

Here, the first vehicle speed threshold value v_th1 and the second vehicle speed threshold value v_th2 are the lower limit value and the upper limit value of the vehicle speed v determined from the viewpoint of ensuring the estimation accuracy of the road noise value, respectively. Further, the first vehicle speed threshold value v_th1 and the second vehicle speed threshold value v_th2 may be set to fixed values that are experimentally determined in advance, or may be set to variable values that change according to the traveling state, etc. of the vehicle <NUM>. Particularly, for the first vehicle speed threshold value v_th1 and the second vehicle speed threshold value v_th2, a predetermined hysteresis may be set in the same manner as the aforementioned first torque threshold value Tm_th1 and second torque threshold value Tm_th2.

Next, in Step S230, the estimation state determining unit <NUM> determines whether or not the slip flag fsl set in the aforementioned slip determining process is "<NUM>". When the determination result is negative, the estimation state determining unit <NUM> proceeds to Step S270, sets the proper estimation flag fop to "<NUM>", and terminates this routine. That is, in this case, it is determined that an error may be included in the calculated value of the angular acceleration A for estimating the road noise value due to the slip of the vehicle <NUM>. On the other hand, when the estimation state determining unit <NUM> determines that the slip flag fsl is "<NUM>", the process of Step S240 is executed.

In Step S240, the estimation state determining unit <NUM> determines whether or not the CAN validity flag fcan is "<NUM>". When the estimation state determining unit <NUM> determines that the CAN validity flag fcan is not "<NUM>", it proceeds to Step S270, sets the proper estimation flag fop to "<NUM>", and terminates this routine. That is, in this case, it is assumed that the input parameters such as the wheel speed W for calculating the angular acceleration A cannot be acquired normally, and it is determined that the estimation accuracy of the road noise value may decrease. On the other hand, when the estimation state determining unit <NUM> determines that the CAN validity flag fcan is "<NUM>", the process of Step S250 is executed.

In Step S250, the estimation state determining unit <NUM> determines whether or not the number of variance samples is equal to or greater than a certain value. Specifically, the estimation state determining unit <NUM> determines whether or not a sufficient number of calculated values of the angular acceleration A are obtained from the viewpoint of suitably calculating the aforementioned angular acceleration variance value var_A based on the timing when it is detected that all the determination results of the aforementioned Step S200-Step S250 are positive.

Then, when the estimation state determining unit <NUM> determines that the number of variance samples is not equal to or higher than a certain value, it proceeds to Step S270, sets the proper estimation flag fop to "<NUM>", and terminates this routine. That is, in this case, it is determined that the number of input data (more specifically, the number of wheel speeds w detected) for determining the appropriate angular acceleration variance value var_A is insufficient from the viewpoint of ensuring the estimation accuracy of the road noise value, and the proper estimation flag fop is set to "<NUM>". On the other hand, when the estimation state determining unit <NUM> determines that the number of variance samples is equal to or higher than a certain value, the process of Step S260 is executed. Further, in the determination of Step S250, when the determination result is negative at a certain control timing, a delay process that stands by until the number of variance samples is ensured (that is, until the determination result becomes positive) may be adopted.

Then, when all the determination results of the aforementioned Step S200-Step S250 are positive, in Step S260, the estimation state determining unit <NUM> sets the proper estimation flag fop to "<NUM>" and terminates this routine. That is, in this embodiment, when all the determination results of the aforementioned Step S200-Step S250 are positive, it is determined that the estimation accuracy of the road noise value is ensured at or above a certain level, and the proper estimation flag fop is set to "<NUM>".

Returning to <FIG>, the estimation state determining unit <NUM> outputs the set proper estimation flag fop to the road surface level setting unit <NUM>.

On the other hand, the variance value correcting unit <NUM> corrects the angular acceleration variance value var_A using inputs of the vehicle speed v, the steering angle θ, and the angular acceleration variance value var_A. Specifically, the variance value correcting unit <NUM> corrects the angular acceleration variance value var_A using a table in which the correction coefficients corresponding to the vehicle speed v and the steering angle θ are determined. Particularly, in this embodiment, correction is performed in a manner that the angular acceleration variance value var_A decreases as the vehicle speed v or the steering angle θ increases. In addition, instead of or in addition to the correction of the angular acceleration variance value var_A based on this vehicle speed v and steering angle θ, a configuration, in which the threshold value to be compared with the angular acceleration variance value var_A is corrected according to the vehicle speed v and the steering angle θ, may be adopted in the process of setting the road surface level Le in the road surface level setting unit <NUM> to be described later.

The significance of this correction will be explained. When a steering operation is performed, the wheels <NUM> slip slightly as compared to when no steering operation is performed, and therefore, when the wheels <NUM> get over a convex part on an uneven road surface, the dispersion of the angular acceleration A of the wheels <NUM> tends to be larger than expected. Therefore, when a steering operation is performed, correction is performed to reduce the angular acceleration variance value var_A according to the magnitude of the vehicle speed v from the viewpoint of maintaining the estimation accuracy of the road noise value. Then, the variance value correcting unit <NUM> outputs the corrected angular acceleration variance value var_A_c to the road surface level setting unit <NUM>.

The road surface level setting unit <NUM> sets the above-mentioned road surface level Le using inputs of the angular acceleration variance value var_A_c and the proper estimation flag fop. Particularly, the road surface level setting unit <NUM> sets the road surface level Le to "<NUM>" regardless of the angular acceleration variance value var_A_c when the proper estimation flag fop is set to "<NUM>" (that is, when the estimation state of the road noise value is not the proper estimation state).

On the other hand, the road surface level setting unit <NUM> sets the road surface level Le to "<NUM>"-"<NUM>" according to the magnitude of the road noise value (that is, the angular acceleration variance value var_A_c) when the proper estimation flag fop is set to "<NUM>" (when the estimation state of the road noise value is the proper estimation state). More specifically, the road surface level setting unit <NUM> sets three threshold values for the angular acceleration variance value var_A_c, and allocates "<NUM>", "<NUM>", "<NUM>", and "<NUM>" as the road surface level Le to each range of the four angular acceleration variance values var_A_c defined by the <NUM> threshold values, respectively. Then, the road surface level setting unit <NUM> outputs the set road surface level Le to the sound vibration start determining unit <NUM>.

Further, in this embodiment, the case where the road surface level Le is set to "<NUM>", "<NUM>", or "<NUM>" corresponds to the low background noise state, and the case where the road surface level Le is set to "<NUM>" or "<NUM>" corresponds to the high background noise state.

Returning to <FIG>, the sound vibration start determining unit <NUM> executes the sound vibration start determining process for determining whether or not to enable the control (hereinafter also referred to as "sound vibration start control") for adjusting the value of the required output Pr at which the engine <NUM> should be started (hereinafter also referred to as "start threshold value Pr_sth") or the value of the required output Pr at which the engine <NUM> should be stopped (hereinafter also referred to as "stop threshold value Pr_eth") according to the magnitude of the road surface level Le using inputs of the road surface level Le, the proper estimation flag fop, and the vehicle speed v. Particularly, in the estimation state determining process of this embodiment, the deactivation flag fno is set to "<NUM>" when the sound vibration start determining process should be executed, and is set to "<NUM>" when the sound vibration start determining process should not be executed. The details of the sound vibration start determining process will be described below. Further, in this embodiment, it is assumed that the initial value of the deactivation flag fno is set to either "<NUM>" or "<NUM>" when the vehicle <NUM> is started (when the ignition switch is turned on).

<FIG> and <FIG> are flowcharts explaining the sound vibration start determining process. Particularly, <FIG> is a flowchart explaining the determination of setting the deactivation flag fno to "<NUM>" to deactivate the sound vibration start control (deactivation flag setting determination). Further, <FIG> is a flowchart explaining the determination of clearing the deactivation flag fno set based on the process of <FIG> (deactivation flag clear determination).

First, in the deactivation flag setting determination shown in <FIG>, in Step S300, the sound vibration start determining unit <NUM> determines whether or not the proper estimation flag fop is set to "<NUM>". Then, when the sound vibration start determining unit <NUM> determines that the proper estimation flag fop is "<NUM>", the processes from Step S310 are executed.

In Step S310, the sound vibration start determining unit <NUM> sets the control unit distance du. Here, the control unit distance du is the distance traveled by the vehicle <NUM> during a preset calculation period Δt (for example, <NUM>). That is, the control unit distance du is defined as a value obtained by multiplying the vehicle speed v by the calculation period Δt, and is a variable amount according to the magnitude of the vehicle speed v.

In Step S320, the sound vibration start determining unit <NUM> calculates the road surface determination accumulated travel distance D. Specifically, first, the sound vibration start determining unit <NUM> acquires the total travel distance of the vehicle <NUM> from the start of the vehicle <NUM> (for example, the timing when the ignition switch is turned on) to the current control period. Then, the sound vibration start determining unit <NUM> calculates the travel distance at the time of proper estimation, that is, the distance traveled by the vehicle <NUM> with the proper estimation flag fop set to "<NUM>" from the start of the vehicle <NUM> to the current control period. More specifically, the sound vibration start determining unit <NUM> obtains the road surface determination accumulated travel distance D by multiplying the number of controls whose proper estimation flag fop is set to "<NUM>" by the above control unit distance du.

In Step S330, the sound vibration start determining unit <NUM> calculates the accumulated rough road travel distance Dba. Specifically, the sound vibration start determining unit <NUM> obtains the accumulated rough road travel distance Dba by multiplying the number of controls whose proper estimation flag fop is set to "<NUM>" and road surface level Le set to "<NUM>" or "<NUM>" by the above control unit distance du from the start of the vehicle <NUM> to the current control period.

Then, in Step S340, the sound vibration start determining unit <NUM> calculates the rough road continuation rate Rbc. Specifically, the sound vibration start determining unit <NUM> divides the accumulated rough road travel distance Dba by the road surface determination accumulated travel distance D to obtain the rough road continuation rate Rbc.

Next, in Step S350, the sound vibration start determining unit <NUM> determines whether or not the rough road continuation rate Rbc is equal to or greater than a predetermined rough road continuation rate threshold value Rbc_th in the state that the vehicle <NUM> has traveled over a predetermined travel distance D_th. Specifically, the sound vibration start determining unit <NUM> calculates the predetermined travel distance D_th by multiplying the predetermined number of controls by the above control unit distance du. Then, the sound vibration start determining unit <NUM> determines whether or not the rough road continuation rate Rbc is equal to or greater than the rough road continuation rate threshold value Rbc_th in the control period during the traveling over the predetermined travel distance D_th. In addition, the rough road continuation rate threshold value Rbc_th is set to a suitable value from the viewpoint of determining whether or not an erroneous determination continues in the determination on whether the traveling road of the vehicle <NUM> is "rough road" or "smooth road" (determination based on the road surface level Le).

Particularly, the rough road continuation rate threshold value Rbc_th is set from the viewpoint of determining whether or not the operating time of the engine <NUM> becomes longer and the fuel consumption is reduced when the operation of the sound vibration start control is enabled. More specifically, it is assumed that by continuing a state in which the erroneous determination that the vehicle <NUM> is traveling on a "rough road" is maintained for a certain period of time or more to enable the operation of the sound vibration start control (a state where the engine <NUM> is easy to start or difficult to stop), the battery SOC will rise and the engine <NUM> will start and stop frequently. Therefore, the rough road continuation rate threshold value Rbc_th is set to a suitable value from the viewpoint of suppressing such a situation.

Then, when the sound vibration start determining unit <NUM> determines that the rough road continuation rate Rbc is equal to or greater than the rough road continuation rate threshold value Rbc_th over the predetermined travel distance D_th, it proceeds to Step S360, sets the deactivation flag fno to "<NUM>", and terminates this routine. That is, in this case, the sound vibration start control is invalidated. On the other hand, when the above determination result is negative, the sound vibration start determining unit <NUM> proceeds to Step S370 and terminates this routine while maintaining the deactivation flag fno.

On the other hand, in Step S300, when the sound vibration start determining unit <NUM> determines that the proper estimation flag fop is not "<NUM>" (determines that it is "<NUM>"), it shifts to the process of Step S340. That is, when it is determined that the estimation state of the road noise value is not proper in this control period, the sound vibration start determining unit <NUM> calculates the rough road continuation rate Rbc without executing the calculation of the road surface determination accumulated travel distance D in Step S320 and the calculation of the accumulated rough road travel distance Dba in Step S330.

Thereby, if the vehicle <NUM> continues to travel in a state where the estimation state of the road noise value is not proper, the distance related to the traveling can be excluded from the calculation target of the road surface determination accumulated travel distance D, and it is possible to suppress a decrease in the accuracy of the calculated rough road continuation rate Rbc. More specifically, by adding the distance in the state where the estimation state of the road noise value is not proper to the road surface determination accumulated travel distance D so that the rough road continuation rate Rbc is calculated to be lower than the assumed value, the phenomenon of switching between the operation and non-operation of the sound vibration start control based on an erroneous determination is suppressed.

In addition, it is preferable that the sound vibration start determining unit <NUM> is configured to reset the road surface determination accumulated travel distance D calculated in Step S320 above to <NUM> in the control period from switching the deactivation flag fno from "<NUM>" to "<NUM>". Thereby, in the scene where the vehicle <NUM> travels a relatively long distance from the start, it is suppressed that the road surface determination accumulated travel distance D becomes a large value and the rate of change of the rough road continuation rate Rbc obtained by dividing the accumulated rough road travel distance Dba by the road surface determination accumulated travel distance D becomes small. As a result, the accuracy of erroneous determination based on the rough road continuation rate Rbc can be further improved.

Next, the deactivation flag clear determination shown in <FIG> will be described.

First, in Step S380, the sound vibration start determining unit <NUM> determines whether or not the deactivation flag fno is set to "<NUM>". Then, when the sound vibration start determining unit <NUM> determines that the deactivation flag fno is not "<NUM>" (determines that it is "<NUM>"), the sound vibration start determining unit <NUM> terminates this routine. On the other hand, when the sound vibration start determining unit <NUM> determines that the deactivation flag fno is "<NUM>", the processes from Step S381 are executed.

In Step S381, the sound vibration start determining unit <NUM> determines whether or not a smooth road continuation rate Rgc is equal to or greater than a predetermined smooth road continuation rate threshold value Rgc_th in a state of having traveled over the predetermined travel distance D_th. Specifically, the sound vibration start determining unit <NUM> calculates the predetermined travel distance D_th by the same method as the process in Step S350 described above. Then, the sound vibration start determining unit <NUM> determines whether or not the smooth road continuation rate Rgc is equal to or greater than the smooth road continuation rate threshold value Rgc_th in the control period during the traveling over the predetermined travel distance D_th.

Here, the smooth road continuation rate Rgc is a value obtained by dividing the accumulated smooth road travel distance Dgc by the aforementioned road surface determination accumulated travel distance D. Further, the accumulated smooth road travel distance Dgc can be calculated by multiplying the number of controls in which the road surface level Le is set to any of "<NUM>"-"<NUM>" by the above control unit distance du. Further, the smooth road continuation rate Rgc may be obtained by subtracting the rough road continuation rate Rbc obtained in Step S340 from <NUM> (corresponding to the total road surface determination accumulated travel distance D). Further, the smooth road continuation rate threshold value Rgc_th is set to a suitable value from the viewpoint of determining that the smooth road determination based on the road surface level Le continues to the extent that the deactivation flag fno can be cleared (that is, determining that a rough road traveling determination based on an erroneous determination has not occurred).

Particularly, the smooth road continuation rate threshold value Rgc_th is set to a suitable value from the viewpoint of suppressing the situation where the engine <NUM> does not operate even in a required scene due to the fact that the deactivation flag fno, which is set from the viewpoint of suppressing the execution of the sound vibration start control on the basis of the rough road determination based on the above-mentioned erroneous determination, is always set to "<NUM>".

Then, when the sound vibration start determining unit <NUM> determines that the smooth road continuation rate Rgc is equal to or greater than the smooth road continuation rate threshold value Rgc_th over the predetermined travel distance D_th, the sound vibration start determining unit <NUM> proceeds to Step S382, sets the deactivation flag fno to "<NUM>", and terminates this routine. That is, in this case, the sound vibration start control switches from the invalid state to the valid state. On the other hand, when the above determination result is negative, the sound vibration start determining unit <NUM> proceeds to Step S383 and terminates this routine while maintaining the deactivation flag fno.

Returning to <FIG>, the sound vibration start determining unit <NUM> outputs the set deactivation flag fno to the start/stop flag setting unit <NUM>.

The start/stop flag setting unit <NUM> executes the start/stop flag setting processes (start flag setting process and stop flag setting process) which set the start flags fst (normal start flag fust and rough road start flag fbst) for starting the engine <NUM> and the stop flags fen (normal stop flag fuen and rough road stop flag fben) for stopping the engine <NUM> using inputs of the battery SOC, deactivation flag fno, and target motor torque Tm.

<FIG> is a flowchart explaining the start flag setting process.

First, in Step S410 and Step S420, the start/stop flag setting unit <NUM> sets the normal start threshold value Pr_suth and the rough road start threshold value Pr_sbth.

Here, the normal start threshold value Pr_suth is set as the value of the required output Pr that defines the start timing, which is defined from the viewpoint of operating the engine <NUM> at the operating point with as good driving efficiency as possible (the operating point close to the optimum fuel consumption point) while keeping the battery SOC in an appropriate range. Therefore, the normal start threshold value Pr_suth of this embodiment is prepared in advance in the form of a map using variables of the required output Pr, vehicle speed v, and battery SOC.

On the other hand, the rough road start threshold value Pr_sbth is set as the value of the required output Pr that defines the start timing, which is defined from the viewpoint of making the engine <NUM> easier to start than when the normal start threshold value Pr_suth is set, as long as the battery SOC does not exceed an appropriate range. That is, the rough road start threshold value Pr_sbth is set to a value equal to or less than the normal start threshold value Pr_suth, and is prepared in advance in the form of a map using variables of the required output Pr, vehicle speed v, and battery SOC.

Next, in Step S430, the start/stop flag setting unit <NUM> determines whether or not the deactivation flag fno is "<NUM>". Then, when the start/stop flag setting unit <NUM> determines that the deactivation flag fno is "<NUM>" (when the sound vibration start control is invalid), the start/stop flag setting unit <NUM> shifts to the process of Step S440.

In Step S440, the start/stop flag setting unit <NUM> determines whether or not the required output Pr is equal to or greater than the normal start threshold value Pr_suth. Then, when the start/stop flag setting unit <NUM> determines that the required output Pr is equal to or greater than the normal start threshold value Pr_suth, the start/stop flag setting unit <NUM> sets the normal start flag fust as the start flag fst in Step S460 and terminates this process.

On the other hand, when the start/stop flag setting unit <NUM> determines that the deactivation flag fno is "<NUM>" in Step S430 (when the sound vibration start control is valid), the start/stop flag setting unit <NUM> shifts to the process of Step S450.

In Step S450, the start/stop flag setting unit <NUM> determines whether or not the required output Pr is equal to or greater than the rough road start threshold value Pr_sbth. Then, when the start/stop flag setting unit <NUM> determines that the required output Pr is equal to or greater than the rough road start threshold value Pr_sbth, it sets the rough road start flag fbst as the start flag fst in Step S470 and terminates this process.

According to the start flag setting process described above, when the sound vibration start control is valid, a start flag fst (rough road start flag fbst) will be set when the required output Pr is equal to or greater than the rough road start threshold value Pr_sbth which is less than the normal start threshold value Pr_suth.

<FIG> is a flowchart explaining the stop flag setting process.

First, in Step S510 and Step S520, the start/stop flag setting unit <NUM> sets the normal stop threshold value Pr_euth and the rough road stop threshold value Pr_ebth.

Here, the normal stop threshold value Pr_euth is set as the value of the required output Pr that defines the stop timing which can sufficiently ensure the battery SOC even if the engine <NUM> is stopped (power generation is stopped). The normal stop threshold value Pr_euth is prepared in advance in the form of a map using variables of the required output Pr, vehicle speed v, and battery SOC.

On the other hand, the rough road stop threshold value Pr_ebth is set as the value of the required output Pr that defines the stop timing which makes it more difficult to stop the engine <NUM> as long as the battery SOC can be kept within an appropriate range. That is, the rough road stop threshold value Pr_ebth is set to a value equal to or less than the normal stop threshold value Pr_euth, and is prepared in advance in the form of a map using variables of the required output Pr, vehicle speed v, and battery SOC.

In Step S530, the start/stop flag setting unit <NUM> determines whether or not the rough road start flag fbst is set as the start flag fst. Then, when the start/stop flag setting unit <NUM> determines that the rough road start flag fbst is set, the start/stop flag setting unit <NUM> shifts to the process of Step S550, and when the start/stop flag setting unit <NUM> determines that the rough road start flag fbst is not set, the start/stop flag setting unit <NUM> shifts to the process of Step S540.

In Step S540, the start/stop flag setting unit <NUM> determines whether or not the vehicle <NUM> is currently traveling on a rough road. Specifically, the start/stop flag setting unit <NUM> determines that the vehicle <NUM> is traveling on a rough road if the road surface level Le set at the current control timing is "<NUM>" or higher, and otherwise determines that the vehicle <NUM> is traveling on a smooth road.

Then, the start/stop flag setting unit <NUM> shifts to the process of Step S550 when the start/stop flag setting unit <NUM> determines that the vehicle <NUM> is currently traveling on a rough road, and shifts to the process of Step S560 when the start/stop flag setting unit <NUM> determines that the vehicle <NUM> is traveling on a smooth road.

In Step S550, the start/stop flag setting unit <NUM> determines whether or not the required output Pr is equal to or less than the rough road stop threshold value Pr_ebth. Then, when the start/stop flag setting unit <NUM> determines that the required output Pr is equal to or less than the rough road stop threshold value Pr_ebth, the start/stop flag setting unit <NUM> sets the rough road stop flag fben as the stop flag fen (Step S570) and terminates this process. On the other hand, when the start/stop flag setting unit <NUM> determines that the required output Pr is not equal to or less than the rough road stop threshold value Pr_ebth, it terminates this process without setting a stop flag fen.

In Step S560, the start/stop flag setting unit <NUM> determines whether or not the required output Pr is equal to or less than the normal stop threshold value Pr_euth. Then, when the start/stop flag setting unit <NUM> determines that the required output Pr is equal to or less than the normal stop threshold value Pr_euth, it sets the normal stop flag fuen as the stop flag fen (Step S580) and terminates this process. On the other hand, when the start/stop flag setting unit <NUM> determines that the required output Pr is not equal to or less than the normal stop threshold value Pr_euth, it terminates this process without setting a stop flag fen.

According to the stop flag setting process described above, when the rough road start flag fbst is set as the start flag fst (when the engine <NUM> starts at the rough road start threshold value Pr_sbth), the rough road stop flag fben is set as the stop flag fen (the engine <NUM> will stop at the rough road stop threshold value Pr_ebth). On the other hand, when the normal start flag fust is set as the start flag fst (when the engine <NUM> starts at the normal start threshold value Pr_suth), the rough road stop flag fben or normal stop flag fuen is set depending on whether the traveling road surface at the time of stop is "rough road" or "smooth road".

<FIG> shows an example of a map that defines the normal start threshold value Pr_suth. rough road start threshold value Pr_sbth, normal stop threshold value Pr_euth, and rough road stop threshold value Pr_ebth. According to the map shown in <FIG>, regarding the rough road start threshold value Pr_sbth, the rough road start threshold value Pr_sbth and rough road stop threshold value Pr_ebth are set to values lower than the normal start threshold value Pr_suth and normal stop threshold value Pr_euth in the low/medium vehicle speed region (the region where the vehicle speed v is equal to or less than the second vehicle speed threshold value v_th2). Particularly, the rough road start threshold value Pr_sbth and rough road stop threshold value Pr_ebth are set to values lower than the normal start threshold value Pr_suth and normal stop threshold value Pr_euth only in the SOC intermediate region where it is easy to tolerate changes in the battery SOC (the region where the battery SOC is difficult to deviate from the appropriate range even if the battery SOC changes), and in other SOC regions, it is preferable to set the rough road start threshold value Pr_sbth (rough road stop threshold value Pr_ebth) and normal start threshold value Pr_suth (normal stop threshold value Pr_euth) to substantially the same value. Thereby, it is possible to suppress overcharge or overdischarge of the battery <NUM> due to the execution of the sound vibration start control, or frequent start and stop of the engine <NUM> due to the battery SOC moving in and out of the appropriate range.

Further, the rough road start threshold value Pr_sbth and the normal start threshold value Pr_suth are set so that they become smaller values as the battery SOC becomes lower. Further, the rough road stop threshold value Pr_ebth and the normal stop threshold value Pr_euth are set so that they become larger values as the battery SOC becomes larger.

Returning to <FIG>, the start/stop flag setting unit <NUM> outputs the set start flag fst and stop flag fen to the target power generation operating point setting unit <NUM>.

The target power generation operating point setting unit <NUM> sets the operating point of the engine <NUM> using inputs of the start flag fst and stop flag fen. Specifically, the target power generation operating point setting unit <NUM> sets the target rotation speed Ne and target torque Te of the engine <NUM> in a manner that the fuel economy can be improved as much as possible within the range where the battery SOC can be maintained in the appropriate range (close to the optimum fuel economy point) according to the start timing and stop timing of the engine <NUM> defined by the start flag fst and stop flag fen. Then, the target power generation operating point setting unit <NUM> outputs the set target rotation speed Ne and target torque Te of the engine <NUM> to the power generator <NUM> (particularly, the unillustrated inverter of the power generator <NUM>) and the engine <NUM> (particularly, the unillustrated engine controller), respectively.

<FIG> is a diagram illustrating a control result in which the control method according to this embodiment is applied to a specific traveling scene of the vehicle <NUM>. <FIG> shows the section where the sound vibration start control is enabled. Further, <FIG> shows the change over time in the battery SOC. Further, <FIG> shows the change over time in the required output Pr, start threshold value Pr_sth, and stop threshold value Pr_eth. Particularly, the rough road start threshold value Pr_sbth and normal start threshold value Pr_suth are indicated by bold solid lines and bold dashed lines, respectively, and the rough road stop threshold value Pr_ebth and normal stop threshold value Pr_euth are indicated by thin solid lines and thin dashed lines, respectively.

As illustrated, the sound vibration start control is enabled by continuing the state of traveling on a "smooth road" until time t1 (Yes in Step S381 and Step S382 of <FIG>). Then, at time t1, the vehicle <NUM> starts traveling on a "rough road" and the sound vibration start control is started.

Then, at time t2, when the required output Pr becomes equal to or greater than the rough road start threshold value Pr_sbth, the rough road start flag fbst is set and the engine <NUM> starts (Yes in Step S450, and Step S470). Along with this, power generation is started and the battery SOC starts to increase.

Next, at time t3, the rough road continuation rate Rbc exceeds the rough road continuation rate threshold value Rbc_th, and the sound vibration start control becomes invalid (Yes in Step S350 and Step S360 in <FIG>). Then, the required output Pr becomes equal to or less than the rough road stop threshold value Pr_ebth during the travel on a rough road, the rough road stop flag fben is set, and the engine <NUM> stops (Yes in Step S540, Yes in Step S550, and Step S570). Along with this, power generation stops and the battery SOC starts to decrease.

According to the control method of this embodiment described above, there is realized a control, which makes it easier to start the engine <NUM> but makes it harder to stop the engine <NUM> than when the background noise of the vehicle <NUM> is in the low background noise state (when the road surface level Le is "<NUM>"-"<NUM>") if the background noise of the vehicle <NUM> is in the high background noise state (when the road surface level Le is "<NUM>" or "<NUM>"). Therefore, when the vehicle <NUM> is traveling, the generated power amount required according to the required output Pr and the battery SOC can be satisfied while reducing the discomfort given to the occupant by the noise of the engine <NUM>.

Next, modifications to the control method described in the above embodiment will be described.

A configuration, in which the execution and non-execution of the slip determining process, the estimation state determining process, or the sound vibration start determining process are switched by a predetermined switch (ignition switch, etc.) operated by the occupant, etc. of the vehicle <NUM>, may be adopted. For example, a configuration in which the proper estimation flag fop is set to "<NUM>" in preference to the estimation state determining process, or a configuration in which the deactivation flag fno is set to "<NUM>" in preference to the sound vibration start determining process, may be adopted. Thereby, it is possible to select a mode in which the occupant, etc. of the vehicle <NUM> start the engine <NUM> if desired or a mode in which the engine <NUM> is not started.

The in-vehicle actuator to which the control method of this embodiment is applied is not limited to the engine <NUM>. That is, if a device emits a certain operating sound (noise) to the extent that the occupant of the vehicle <NUM> may feel uncomfortable when the road noise value is small, the control described in the above embodiment can be applied with several modifications. Examples of such an in-vehicle actuator include air conditioner, fan, navigation system, and audio. Further, as another in-vehicle actuator, for a traveling sound generator that generates a sound that imitates the driving sound of the engine <NUM> in order to make people around the traveling vehicle <NUM> recognize the existence of the vehicle <NUM>, the control method of this embodiment may be applied.

In this embodiment, the road surface level Le, which is an index of the magnitude of the background noise of the vehicle <NUM>, is not limited to the <NUM> stages of "<NUM>"-"<NUM>". That is, the road surface level Le is an index of the magnitude of background noise of the vehicle <NUM> based on the road noise value itself and the estimation state for the road noise value, and if it is possible to separate the high background noise state from the low background noise state, it is possible to set the index to any number of stages. Further, the index of the magnitude of background noise of the vehicle <NUM> may be expressed by a parameter of continuous quantity.

Instead of or together with the angular acceleration A of the wheels <NUM> as the detection parameter for calculating the road noise value, any other detection parameters that correlate to the magnitude of road noise may be adopted. Such detection parameters include, for example, an angular acceleration of tire, a traveling sound directly detected using a microphone, etc., a G sensor detected value (correlated to changes in acceleration due to road surface conditions), and a suspension change amount (a change due to road surface conditions), etc..

A configuration, in which the execution and non-execution of the slip determining process, the estimation state determining process, the sound vibration start determining process, or the engine start itself are switched according to a predetermined operation mode set in the vehicle <NUM>, may be adopted. For example, when the operation of the engine <NUM> is limited by the operation on a predetermined switch (when a manner mode is set), or in the state before the first start of the engine <NUM> when the vehicle <NUM> is started (when the power is turned on), the deactivation flag fno may be set to "<NUM>" in preference to the sound vibration start determining process, or the operation of the engine <NUM> itself may be prohibited.

According to this embodiment, an in-vehicle actuator control method for controlling the operation of an in-vehicle actuator which is a noise source is provided. This in-vehicle actuator control method includes: a road noise value estimating step that estimates a road noise value which quantifies a magnitude of a road noise from the angular acceleration A of the wheels <NUM> of the vehicle <NUM> (angular acceleration variance value calculating unit <NUM>, variance value correcting unit <NUM>); an estimation state determining step that determines whether or not the estimation state of the road noise value is the proper estimation state (<FIG>); a background noise state determining step that determines whether the background noise of the vehicle <NUM> is in the high background noise state (road surface level Le="<NUM>"-"<NUM>") in which the background noise of the vehicle <NUM> is relatively large or the low background noise state (road surface level Le="<NUM>"-"<NUM>") in which the background noise of the vehicle <NUM> is relatively small based on the road noise value and the estimation state (road surface level setting unit <NUM>); and an output adjusting step that adjusts the output of the in-vehicle actuator (engine <NUM>) according to the determined background noise state of the vehicle <NUM> (<FIG> and <FIG>).

Then, in the background noise state determining step (sound vibration start determining process), when it is determined that the estimation state is the proper estimation state (when all the determination results of Step S200 to Step S240 in <FIG> are positive), it is determined whether the background noise of the vehicle <NUM> is in the high background noise state or the low background noise state according to magnitudes of the road noise value and a predetermined threshold value (road surface level Le="<NUM>" and "<NUM>") (Step S300 is Yes, and Step S310 to Step S350). Further, in the background noise state determining step, when it is determined that the estimation state is not the proper estimation state (Step S300 is No), it is determined that the background noise of the vehicle <NUM> is in the low background noise state regardless of the road noise value (Step S360).

Further, in the output adjusting step, when it is determined that the background noise of the vehicle <NUM> is in the high background noise state, the output of the in-vehicle actuator is set so that the noise accompanying the operation of the in-vehicle actuator (the noise accompanying the operation of the engine <NUM>) becomes relatively large. On the other hand, when it is determined that the background noise of the vehicle <NUM> is in the low background noise state, the output of the in-vehicle actuator is set so that the noise accompanying the operation of the in-vehicle actuator becomes relatively small.

This increases the output of the in-vehicle actuator in the high background noise state where it is difficult for the occupant of the vehicle <NUM> to recognize the noise accompanying the operation of the in-vehicle actuator, while the control of decreasing the output of the in-vehicle actuator is realized in the low background noise state where it is easily to recognize the noise. Particularly, when the estimation accuracy of the road noise value (detection accuracy of the angular acceleration A) is low, by determining that the background noise of the vehicle <NUM> is in the low background noise state regardless of the road noise value, it is possible to prevent the situation where the output of the in-vehicle actuator is set high in the low background noise state based on an erroneous determination. As a result, it is possible to more reliably prevent giving an uncomfortable feeling to the occupant due to a noise accompanying an operation of an in-vehicle actuator.

Further, in this embodiment, an in-vehicle actuator control apparatus (controller <NUM>) that executes the above-mentioned in-vehicle actuator control method is provided. Particularly, the controller <NUM> functions as the road noise value estimating units (the angular acceleration variance value calculating unit, and the variance value correcting unit <NUM>, and the road surface level setting unit <NUM>) that execute the road noise value estimating step, the estimation state determining unit <NUM> that executes the aforementioned estimation state determining step, the background noise state determining unit (the road surface level setting unit <NUM>) that executes the background noise state determining step, and the output adjusting unit (the start/stop flag setting unit <NUM> or the target power generation operating point setting unit <NUM>) that executes the output adjusting step.

Further, in the estimation state determining step of this embodiment, when the mechanical brake of the vehicle <NUM> is operating, it is determined that the estimation state of the road noise value is not the proper estimation state (No in Step S200, and Step S270).

That is, it is possible to set the mechanical brake operation time when the friction force acting on the wheels <NUM> is a disturbance element against the angular acceleration A for estimating the road noise value as a specific scene for determining that the estimation state of the road noise value is not the proper estimation state. Further, in the vehicle <NUM> of this embodiment, a regenerative brake, which adjusts the regenerative force of the drive motor <NUM> according to the decrease amount in the accelerator opening APO to perform braking, is mounted as a braking function in addition to the mechanical brake. Therefore, depending on the braking scene, it is assumed that regenerative braking is executed more frequently than mechanical braking. Thus, even if a control logic, which determines that the vehicle is not in the proper estimation state when the mechanical brake operates, is adopted, the situation where it is always determined that the vehicle is not in the proper estimation state in the braking scene of the vehicle <NUM> (the situation where the output of the in-vehicle actuator is always set low during braking) is suppressed.

Further, in the estimation state determining step according to the invention, when the wheels <NUM> slip, it is determined that the estimation state of the road noise value is not the proper estimation state (the slip determining process in <FIG> and <FIG>). That is, it is possible to set the slip time when the vibration of the angular acceleration A due to the idling of the wheels <NUM> becomes a disturbance element as a specific scene for determining that the estimation state is not the proper estimation state.

Further, in the estimation state determining step of this embodiment, when the acceleration (estimated value of forward/backward G) of the vehicle <NUM> is greater than a predetermined acceleration (detected value of forward/backward G) defined from the viewpoint of determining a rapid deceleration or rapid acceleration of the vehicle <NUM>, it is determined that the wheels <NUM> are slipping (Yes in Step S150). That is, there is realized a logic that the scene of rapid deceleration or rapid acceleration, in which a stronger braking force or driving force is a disturbance element as compared with the scene of normal deceleration or acceleration, is determined as a scene where there is a risk of slipping.

Further, there may adopt a configuration in which it is determined that the wheels <NUM> are slipping when the target motor torque Tm of the drive motor <NUM>, which is the travel drive source mounted on the vehicle <NUM> instead of or together with the acceleration of the vehicle <NUM>, is larger than the predetermined driving force defined from the viewpoint of determining the rapid deceleration or rapid acceleration of the vehicle <NUM>. Particularly, in a scene where the vehicle <NUM> starts or stops on a slope road, it is assumed that the deceleration or acceleration is relatively small even during a rapid deceleration or rapid acceleration. That is, depending on the traveling scene, it is assumed that the time of rapid deceleration or the time of rapid acceleration cannot be specified with high accuracy only in view of the deceleration or acceleration. On the other hand, since the target motor torque Tm is set to include a slope of a traveling path, the increase or decrease due to rapid deceleration or rapid acceleration is preferably reflected even on a slope road. Therefore, it is possible to more suitably identify the case where the vehicle <NUM> is slipping in a specific traveling scene such as when traveling on a slope road.

Further, in this embodiment, the vehicle <NUM> is configured as a series hybrid vehicle in which the power generator <NUM> is driven to charge the battery <NUM> and the battery <NUM> supplies electric power to the drive motor <NUM> for traveling according to the required output Pr, and the in-vehicle actuator is configured as the engine <NUM> for driving the power generator <NUM>.

Then, in the output adjusting step, the start threshold value Pr_sth, which is the threshold value of the required output Pr for permitting the start of the engine <NUM>, is set according to the determined background noise state of the vehicle <NUM> (road surface level Le is any of "<NUM>" to "<NUM>") (<FIG>, <FIG>). Further, the stop threshold value Pr_eth, which is the threshold value of the required output Pr for permitting the stop of the engine <NUM>, is set (<FIG>, <FIG>).

Particularly, when the required output Pr is equal to or greater than the start threshold value Pr_sth, the start of the engine <NUM> is determined, and when the required output Pr is equal to or less than the stop threshold value Pr_eth, the stop of the engine <NUM> is determined.

Then, if it is determined that the background noise of the vehicle <NUM> is in the high background noise state (road surface level Le = "<NUM>" to "<NUM>"), the start threshold value Pr_sth is set to the relatively smaller first start threshold value (rough road start threshold value Pr_sbth) (Yes in Step S430, and Step S440). Further, the stop threshold value Pr_eth is set to the relatively smaller first stop threshold value (rough road stop threshold value Pr_ebth).

(Yes in Step S540, and Step S550). On the other hand, if it is determined that the background noise of the vehicle <NUM> is in the low background noise state (road surface level Le = "<NUM>" to "<NUM>"), the start threshold value Pr_sth is set to the relatively larger second start threshold value (normal start threshold value Pr_suth) (No in Step S430, and Step S450). Further, the stop threshold value Pr_eth is set to the relatively larger second stop threshold value (normal stop threshold value Pr_euth) (No in Step S540, and Step S560).

As described above, the engine <NUM> in the series hybrid type vehicle <NUM> is assumed as the in-vehicle actuator by the control method described in the above embodiment, and by changing the required output Pr that starts or stops the engine <NUM> as the output adjustment thereof, the start timing and stop timing of the engine <NUM> can be adjusted so as not to cause noise-induced discomfort to the occupant when the vehicle <NUM> is traveling.

According to this embodiment, the engine control method and the engine control apparatus, which are one aspect of the above-mentioned in-vehicle actuator control method and in-vehicle actuator control apparatus, are provided.

In the engine control method of this embodiment, the start threshold value Pr_sth, which is the threshold value of the required output Pr for starting the engine <NUM>, is set in the series hybrid type vehicle <NUM> in which the power generator <NUM> is driven by the engine <NUM> to charge the battery <NUM> and the battery <NUM> supplies electric power to the drive motor <NUM> for traveling according to the required output Pr. Thus, this engine control method includes: a background noise state determining step that determines whether the background noise of the vehicle <NUM> is in the high background noise state (road surface level Le="<NUM>"-"<NUM>") in which the background noise of the vehicle <NUM> is relatively large or the low background noise state (road surface level Le="<NUM>"-"<NUM>") in which the background noise of the vehicle <NUM> is relatively small (road surface level setting unit <NUM>); and a start/stop threshold value setting step that sets the start threshold value Pr_sth according to the background noise state of the vehicle <NUM> (start flag setting process).

Then, in the start/stop threshold value setting step, if it is determined that the background noise of the vehicle <NUM> is in the high background noise state, the start threshold value Pr_sth is set to the relatively smaller first start threshold value (rough road start threshold value Pr_sbth) (No in Step S430, and Step S450), and if it is determined that the background noise of the vehicle <NUM> is in the low background noise state, the start threshold value Pr_sth is set to the relatively larger second start threshold value (normal start threshold value Pr_suth) (Yes in Step S430, and Step S460).

Further, in the engine control method of this embodiment, the stop threshold value Pr_eth, which is the threshold value of the required output Pr for stopping the engine <NUM>, is set according to the background noise state of the vehicle <NUM> in the start/stop threshold value setting step (stop flag setting process). Then, if it is determined that the background noise of the vehicle <NUM> is in the high background noise state (road surface level Le = "<NUM>" to "<NUM>"), the stop threshold value Pr_eth is set to the relatively smaller first stop threshold value (rough road stop threshold value Pr_ebth) (Yes in Step S540, and Step S550). Further, if it is determined that the background noise of the vehicle <NUM> is in the low background noise state (road surface level Le = "<NUM>" to "<NUM>"), the stop threshold value Pr_eth is set to the relatively larger second stop threshold value (normal stop threshold value Pr_euth) (No in Step S540, and Step S560).

Thereby, it is possible to make it harder to stop the engine <NUM> in the high background noise state than in the low background noise state. As a result, since it is easy to start the engine <NUM> while difficult to stop the engine <NUM> in the high background noise state in the configuration as described above, the amount of power generation (the amount of charge to the battery <NUM>) can be ensured more suitably by increasing the operation time of the engine <NUM> in the high background noise state where the occupant of the vehicle <NUM> is hard to recognize noise. Further, in a situation that the high background noise state continues for a certain period of time, frequent repetition of the start and stop of the engine <NUM> due to the rough road start threshold value Pr_sbth and the rough road stop threshold value Pr_ebth being values close to each other is also suppressed.

Further, in this embodiment, an engine control method (controller <NUM>) that executes the above engine control method is provided. That is, the controller <NUM> functions as the background noise state determining unit (road surface level setting unit <NUM>) that executes the background noise state determining step, and the start/stop threshold value setting unit (start/stop flag setting unit <NUM>) that executes the start/stop threshold value setting step.

Particularly, in the estimation state determining step of this embodiment, the rough road start threshold value Pr_sbth and the normal start threshold value Pr_suth are set to smaller values as the state of charge (battery SOC) of the battery <NUM> is lower. Thereby, it is possible to start the engine <NUM> in a manner that the battery SOC does not fall below the appropriate range in both the high background noise state and the low background noise state.

In addition, the engine control method of this embodiment further includes a road noise value estimating step (the angular acceleration variance value calculating unit <NUM> and variance value correcting unit <NUM>) for estimating a road noise value that quantifies the magnitude of road noise from the angular acceleration A of the wheels <NUM> of the vehicle <NUM> (road surface level Le in the range of "<NUM>" to "<NUM>"). Then, in the road surface level setting unit <NUM>, when the road noise value is equal to or greater than a predetermined threshold value (road surface level Le = "<NUM>" and "<NUM>"), it is determined that the background noise of the vehicle <NUM> is in the high background noise state (Step S300 is Yes). Then, when the determination of the high background noise state based on the road noise value continues (when the rough road continuation rate Rbc is equal to or greater than the rough road continuation rate threshold value Rbc_th over the predetermined travel distance D_th), it is determined in a later control that the background noise state of the vehicle <NUM> is the low background noise state regardless of the magnitude relation between the road noise value and the aforementioned threshold value (Yes in Step S350, and Step S360).

Thereby, it is possible to determine whether the background noise state of the vehicle <NUM> is the high background noise state or the low background noise state according to the magnitude relation between the road noise value calculated from the angular acceleration A and the predetermined threshold value. That is, a specific control logic for determining the background noise state of the vehicle <NUM> is realized. Then, if the state in which the road noise value is determined to be equal to or greater than the threshold value continues, the background noise state of the vehicle <NUM> will be determined to be the low background noise state in the subsequent control. Thus, it is possible to more reliably prevent overcharge of the battery <NUM> or deterioration of fuel consumption due to the fact that engine <NUM> keeps being started based on the rough road start threshold value Pr_sbth, which is a value lower than the normal start threshold value Pr_suth.

Particularly, the determination of the continuation of the high background noise state based on the road noise value is made based on whether or not the ratio of the distance traveled by the vehicle <NUM> on a rough road (rough road continuation rate Rbc) is equal to or greater than a reference value (rough road continuation rate threshold value Rbc_th) in a predetermined control period (predetermined travel distance D_th). Thereby, it is possible to define a suitable control period for determining the low background noise state regardless of the road noise value by assuming the actual traveling scene of the vehicle <NUM>. In addition, there may be adopted a configuration in which the continuation of the state that the road noise value is determined to be equal to or greater than the above threshold value is determined based on whether or not the ratio of rough road traveling time in a predetermined control period, instead of the rough road continuation rate Rbc, is equal to or greater than a reference value.

In addition, the engine control method of this embodiment further includes an estimation state determining step (<FIG>) for determining whether or not the estimation state of the road noise value is the proper estimation state. Then, in the background noise state determining step, the control timing when it is determined that the estimation state is not the proper estimation state is excluded from the above control period (No in Step S300).

Thereby, when the estimation accuracy of the road noise value is not properly maintained according to the traveling scene of the vehicle <NUM>, etc., the situation where it is determined that the above-mentioned high background noise state does not continue based on an erroneous determination (the situation where the background noise state is determined to be the low background noise state as a result) is suppressed. Thereby, it is possible to more reliably prevent giving an uncomfortable feeling to the occupant of the vehicle <NUM> due to operating the engine <NUM> in the low background noise state.

Further, in the engine control method of this embodiment, basically, the start threshold value Pr_sth and the stop threshold value Pr_eth are set so that the amount of power generation that maintains the battery SOC within the appropriate range is realized. That is, since the required amount of power generation is determined with respect to the amount of energy consumed when the vehicle <NUM> travels a certain travel distance (integral value of the required output Pr), the operation time of the engine <NUM> needs to be ensured according to the amount of power generation. On the other hand, by configuring to make both the start threshold value Pr_sth and stop threshold value Pr_eth in the high background noise state to be smaller than those in the low background noise state as mentioned above, the operation time of the engine <NUM> for securing the required amount of power generation can be suitably maintained. In other words, the frequency of the state in which the vehicle <NUM> is traveling without operating the engine <NUM> (EV traveling) can be maintained.

Particularly, in this embodiment, the rough road stop threshold value Pr_ebth and the normal stop threshold value Pr_euth are set to larger values as the battery SOC is higher. Thereby, it is possible to stop the engine <NUM> so that the battery SOC does not exceed the appropriate range in both the high background noise state and the low background noise state.

Further, the engine control method of this embodiment includes: the engine start determining step (<FIG>) that generates the start command (start flag fst) of the engine <NUM> when the required output Pr is equal to or greater than the start threshold value Pr_sth, and the engine stop determining step (<FIG>) that generates the stop command (stop flag fen) of the engine <NUM> when the required output Pr is equal to or less than the stop threshold value Pr_eth.

In the engine start determining step, when the background noise of the vehicle <NUM> is in the high background noise state (No in Step S430), a rough road start flag fbst is generated once the required output Pr becomes equal to or greater than the rough road start threshold value Pr_sbth (Yes in Step S450, and Step S470), and when the background noise of the vehicle <NUM> is in the low background noise state (Yes in Step S430), a normal start flag fust is generated once the required output Pr becomes equal to or greater than the normal start threshold value Pr_suth (Yes in Step S440, and Step S460).

On the other hand, in the engine stop determining step (start/stop flag setting unit <NUM>), when the background noise of the vehicle <NUM> is in the high background noise state (Yes in Step S530), a rough road stop flag fben is generated once the required output Pr becomes equal to or less than the rough road stop threshold value Pr_ebth (Yes in Step S550, and Step S570), and when the background noise of the vehicle <NUM> is in the low background noise state (No in Step S530), a normal stop flag fuen is generated once the required output Pr becomes equal to or less than the normal stop threshold value Pr_euth (Yes in Step S460, and Step S580).

Thus, there is realized a specific control logic for making it easier to start the engine <NUM> but more difficult to stop the engine <NUM> in the high background noise state than in the low background noise state.

Further, in the engine start command step, when the background noise of the vehicle <NUM> continues to be determined to be in the high background noise state (Yes in Step S350, and Step S360), a normal start flag fust is generated once the required output Pr becomes equal to or greater than the normal start threshold value Pr_suth regardless of the determination result of the background noise state of the vehicle <NUM> in a later control (Yes in Step S430, Yes in Step S440, and Step S460).

Thus, there is realized a control logic that even if the determination of being in the high background noise state continues for a certain period of time or longer, the engine <NUM> can be started based on the normal start threshold value Pr_suth without restraining the actual start of the engine <NUM> to the determination. Therefore, it is possible to avoid the above-mentioned overcharge of the battery <NUM> and deterioration of fuel efficiency.

Further, there may be adopted a configuration in the engine stop command step, wherein when the background noise of the vehicle <NUM> continues to be determined to be in the high background noise state, a normal stop flag fuen is generated once the required output Pr becomes equal to or less than the normal stop threshold value Pr_euth regardless of the determination result of the background noise state of the vehicle <NUM> in a later control. With this configuration, it is possible to avoid the overcharge of the battery <NUM> and deterioration of fuel efficiency.

Further, in the engine stop command step in the engine control method of this embodiment, if the engine <NUM> is started when the required output Pr becomes equal to or greater than the rough road start threshold value Pr_sbth (Yes in Step S530), a stop command (rough road stop flag fben) is generated once the required output Pr becomes equal to or less than the rough road stop threshold value Pr_ebth regardless of the background noise state of the vehicle <NUM> (Yes in Step S550, and Step S570). On the other hand, if the engine <NUM> is started when the required output Pr becomes equal to or greater than the normal start threshold value Pr_suth (No in Step S530), a stop flag fen is generated once the required output Pr becomes equal to or less than the rough road stop threshold value Pr_ebth or equal to or less than the normal stop threshold value Pr_euth according to the background noise state of the vehicle <NUM> (Step S540 to Step S580).

Thus, if the engine <NUM> is started based on the rough road start threshold value Pr_sbth which is set in the high background noise state (especially when traveling on a rough road), the engine <NUM> will be stopped based on the rough road stop threshold value Pr_euth for the high background noise state regardless of the background noise state at the time of stop. Therefore, although the relatively small rough road start threshold value Pr_sbth (for rough roads) is applied when the engine <NUM> is started, by applying the relatively large normal stop threshold value Pr_euth (for smooth roads) when stopping the engine <NUM>, the situation in which the engine <NUM> is frequently started and stopped due to the start threshold value Pr_sth and the stop threshold value Pr_eth being close to each other is suppressed.

On the other hand, if the engine <NUM> is started based on the normal start threshold value Pr_suth which is set in the low background noise state (especially when traveling on a smooth road), the start threshold value Pr_sth and stop threshold value Pr_eth are separated from each other to some extent even when the rough road start threshold value Pr_sbth, which is smaller than the originally assumed normal stop threshold value Pr_euth, is applied when stopping the engine <NUM>. Thus, the engine <NUM> can be stopped by applying the normal stop threshold value Pr_euth or a value equal to or less than the rough road stop threshold value Pr_ebth according to the background noise state of the vehicle <NUM> at the time of stopping the engine <NUM>.

Claim 1:
An in-vehicle actuator control method for controlling an operation of an in-vehicle actuator (<NUM>) which is a noise source,
comprising:
- a road noise value estimating step (<NUM>, <NUM>) of estimating a road noise value that quantifies a magnitude of a road noise from an angular acceleration (A) of a wheel (<NUM>) of a vehicle (<NUM>);
- an estimation state determining step (<NUM>) of determining whether or not an estimation state of the road noise value is a proper estimation state;
- a background noise state determining step (<NUM>) of determining whether a background noise of the vehicle (<NUM>) is in a high background noise state in which the background noise of the vehicle (<NUM>) is relatively large or a low background noise state in which the background noise of the vehicle (<NUM>) is relatively small based on the road noise value and the estimation state; and
- an output adjusting step (<NUM>, <NUM>) of adjusting an output of the in-vehicle actuator (<NUM>) according to a determined background noise state of the vehicle (<NUM>),
wherein:
- in the background noise state determining step (<NUM>):
- it is determined whether a background noise of the vehicle (<NUM>) is in the high background noise state or the low background noise state according to magnitudes of the road noise value and a predetermined threshold value when it is determined that the estimation state is the proper estimation state, and
- it is determined that a background noise of the vehicle (<NUM>) is in the low background noise state regardless of the road noise value when it is determined that the estimation state is not the proper estimation state; and
- in the output adjusting step (<NUM>, <NUM>):
- an output of the in-vehicle actuator (<NUM>) is set so that a noise accompanying an operation of the in-vehicle actuator (<NUM>) becomes relatively large when it is determined that the background noise of the vehicle (<NUM>) is in the high background noise state, and
- an output of the in-vehicle actuator (<NUM>) is set so that a noise accompanying an operation of the in-vehicle actuator (<NUM>) becomes relatively small when it is determined that the background noise of the vehicle (<NUM>) is in the low background noise state, and
- in the estimation state determining step (<NUM>), it is determined that an estimation state of the road noise value is not the proper estimation state when the wheel (<NUM>) is slipping.