JP2006204072A - Regenerative braking controller for vechicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a regenerative braking controller for vechicle, capable of easily avoiding an obstacle by turning property causing no incompatibility, when turning operation for avoiding the obstacle is made, while applying regenerative braking to either of the front or the rear wheels, in a situation where there is an obstacle in the running direction of a vehicle. <P>SOLUTION: In the vehicle provided with a regenerative braking control means that performs regenerative braking with the right and the left wheels of either side of the front and rear wheels, based on speed-reduction demand operation, the regenerative braking control means is set to be the means that limits regenerative braking amount to either of the front or the rear wheels, when the vehicle detects the situation where there is an obstacle in its running direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a regenerative braking control device for a vehicle (hybrid vehicle, electric vehicle, etc.) that performs regenerative braking only on one of the front and rear wheels based on a deceleration request operation.

Conventionally, in a vehicle including a driving wheel that can be braked by hydraulic pressure and regeneration and a driven wheel that can be braked by hydraulic pressure, the braking force setting mode has three stages (regeneration priority mode, normal mode, emergency mode), A technique for preventing a sudden change in braking force by smoothly switching between the regeneration priority mode and the normal mode is known. Note that the mode switching control is performed based on the estimated road surface μ (see, for example, Patent Document 1).
JP-A-5-161209

  However, since the conventional regenerative braking control device does not take into account obstacles existing in the traveling direction of the own vehicle, the stop vehicle, the preceding vehicle, and the structure along the road existing in the traveling direction of the own vehicle. In the situation where obstacles that hinder the progress of the vehicle, such as merging vehicles on highways, will be grasped in advance and the obstacle will be avoided by turning operation, regenerative braking force will be applied only to one of the front and rear wheels In this case, the steering characteristic becomes understeer or oversteer, and there is a problem that obstacles cannot be easily avoided.

  For example, when regenerative braking is applied only to the left and right front wheels, the vehicle tends to understeer, so turning necessary to avoid obstacles even if the turning operation is performed with a normal familiar feeling due to the neutral steering state. The actual turning amount is insufficient against the amount, and if regenerative braking is applied only to the left and right rear wheels, the vehicle tends to oversteer, so that the normal steering feel due to the neutral steering state Even if the turning operation is performed, the actual turning amount becomes excessive with respect to the turning amount necessary for avoiding the obstacle, unexpectedly.

  The present invention has been made paying attention to the above problem, and in a situation where there is an obstacle in the traveling direction of the host vehicle, a turning operation for avoiding the obstacle while regeneratively braking only one of the front and rear wheels is performed. An object of the present invention is to provide a regenerative braking control device for a vehicle that can easily avoid an obstacle with a turning characteristic that does not give a sense of incongruity.

In order to achieve the above object, in the vehicle regenerative braking control device according to the present invention, in a vehicle provided with regenerative braking control means for performing regenerative braking only on one of the front and rear wheels based on a deceleration request operation,
The regenerative braking control means limits the regenerative braking amount for only one of the front and rear wheels when detecting a situation where an obstacle is present in the traveling direction of the host vehicle.

  Therefore, in the regenerative braking control device for a vehicle according to the present invention, when the regenerative braking control means detects a situation where an obstacle exists in the traveling direction of the host vehicle, the regenerative braking amount for only one of the front and rear wheels is limited. Is done. That is, by limiting the amount of regenerative braking based on detection of a situation where an obstacle exists, understeer is suppressed in the case of a front-wheel drive vehicle, and oversteer characteristics are suppressed in the case of a rear-wheel drive vehicle. In addition, the steer characteristic can be brought in the neutral steer direction. That is, even if the turning operation is performed with a normal familiar feeling due to the neutral steer state, the excess or deficiency of the actual turning amount with respect to the predicted turning amount can be reduced. As a result, when there is an obstacle in the traveling direction of the host vehicle, when performing a turning operation that avoids the obstacle while regeneratively braking only one of the front and rear wheels, the obstacle is displayed with a turning characteristic without a sense of incongruity. It can be easily avoided.

  Hereinafter, the best mode for realizing a regenerative braking control device for a vehicle according to the present invention will be described based on a first embodiment shown in the drawings.

First, the drive system configuration of the hybrid vehicle will be described.
FIG. 1 is an overall system diagram showing a drive system of a hybrid vehicle to which the regenerative braking control device of Embodiment 1 is applied. As shown in FIG. 1, the drive system of the hybrid vehicle in the first embodiment includes an engine E, a first motor generator MG1, a second motor generator MG2, an output sprocket OS, and a power split mechanism TM.

  The engine E is a gasoline engine or a diesel engine, and the opening degree of a throttle valve and the like are controlled based on a control command from an engine controller 1 described later.

The first motor generator MG1 and the second motor generator MG2 are synchronous motor generators in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator. Based on a control command from the motor controller 2 described later, Each is controlled independently by applying a three-phase alternating current generated by the control unit 3.
Both of the motor generators MG1 and MG2 can operate as electric motors that are rotated by receiving power supplied from the battery 4 (hereinafter, this state is referred to as “powering”), and the rotor is rotated by an external force. If it is, the battery 4 can be charged by functioning as a generator that generates electromotive force at both ends of the stator coil (hereinafter, this operation state is referred to as “regeneration”).

  The power split mechanism TM is configured by a simple planetary gear having a sun gear S, a pinion P, a ring gear R, and a pinion carrier PC. And the connection relationship of the input / output member with respect to the three rotating elements (sun gear S, ring gear R, and pinion carrier PC) of the simple planetary gear will be described. A first motor generator MG1 is connected to the sun gear S. A second motor generator MG2 and an output sprocket OS are connected to the ring gear R. An engine E is connected to the pinion carrier PC via an engine damper ED. The output sprocket OS is connected to the left and right front wheels via a chain belt CB, a differential and a drive shaft (not shown).

Due to the above connection relationship, the first motor generator MG1 (sun gear S), the engine E (planet carrier PC), the second motor generator MG2 and the output sprocket OS (ring gear R) are arranged in this order on the alignment chart shown in FIG. It is possible to introduce a rigid lever model (a relationship in which three rotational speeds are always connected by a straight line) that can simply express the dynamic operation of a simple planetary gear.
Here, the “collinear diagram” is a velocity diagram used in a simple and easy-to-understand method of drawing instead of the method of obtaining by equation when considering the gear ratio of the differential gear, Take the number of rotations (rotation speed) of the rotating elements, take each rotating element on the horizontal axis, and set the interval between each rotating element to the collinear lever ratio (1: λ) based on the gear ratio λ of the sun gear S and ring gear R It arrange | positions so that it may become.

Next, the control system of the hybrid vehicle will be described.
As shown in FIG. 1, the hybrid vehicle control system in the first embodiment includes an engine controller 1, a motor controller 2, a power control unit 3, a battery 4, and a brake controller 5 (mechanical braking force control means). And an integrated controller 6. Note that an auxiliary battery is connected to the battery 4 (high power battery) via a DC / DC converter (not shown) that uses the battery 4 as a power source, and this auxiliary battery is used as an operating power source for each of the controllers 1, 2, 5, and 6. And

The integrated controller 6 includes an accelerator opening sensor 7, a vehicle speed sensor 8, an engine speed sensor 9, a first motor generator speed sensor 10, a second motor generator speed sensor 11, and a communication receiver 27. Input information is provided from the (receiving means) and the inter-vehicle sensor 28.
The communication receiver 27 receives vehicle speed information and acceleration information of a merging vehicle (another vehicle approaching the merging point) transmitted from a vehicle information collecting sensor 29 (vehicle information collecting means) installed at a merging point such as an expressway. (See FIG. 16).
The inter-vehicle sensor 28 is a distance to an obstacle such as a vehicle ahead of the own vehicle (preceding vehicle) or a structure existing in the traveling direction of the own vehicle and the size of the obstacle (basically, the own vehicle avoids it). It is sufficient if the width can be detected in order to determine the required turning amount.) The vehicle speed of the host vehicle is basically determined based on the rotation speed detected by the second motor generator rotation speed sensor 11.

  The brake controller 5 includes a front left wheel speed sensor 12, a front right wheel speed sensor 13, a rear left wheel speed sensor 14, a rear right wheel speed sensor 15, a steering angle sensor 16, and a master cylinder pressure sensor 17. The brake stroke sensor 18 provides input information.

  The engine controller 1 responds to an engine operating point (Ne) according to a target engine torque command or the like from an integrated controller 6 that inputs an accelerator opening AP from an accelerator opening sensor 7 and an engine speed Ne from an engine speed sensor 9. , Te), for example, is output to a throttle valve actuator (not shown).

  The motor controller 2 receives the motor of the first motor generator MG1 in response to a target motor generator torque command or the like from the integrated controller 6 that inputs the motor generator rotational speeds N1 and N2 from the motor generator rotational speed sensors 10 and 11 by the resolver. A command for independently controlling the operating point (N1, T1) and the motor operating point (N2, T2) of the second motor generator MG2 is output to the power control unit 3. The motor controller 2 uses information on the battery S.O.C that indicates the state of charge of the battery 4.

  The power control unit 3 has a joint box, a step-up converter, a drive motor inverter, and a generator generator inverter, not shown, and can supply power to both motor generators MG1 and MG2 with less current with reduced loss. Configure the power supply system high voltage system. A drive motor inverter is connected to the stator coil of the second motor generator MG2, and a generator generator inverter is connected to the stator coil of the first motor generator MG1. The joint box is connected to a battery 4 that is discharged during power running and charged during regeneration.

  The brake controller 5 performs ABS control by a control command to the brake hydraulic pressure unit 19 that independently controls the brake hydraulic pressure of the four wheels during low-μ road braking, sudden braking, etc. At the time of a deceleration request operation by an accelerator release operation or the like, regenerative cooperative brake control is performed by issuing a control command to the integrated controller 6 and a control command to the brake hydraulic pressure unit 19. The brake controller 5 includes wheel speed information from the wheel speed sensors 12, 13, 14, 15, steering angle information from the steering angle sensor 16, braking operation from the master cylinder pressure sensor 17 and the brake stroke sensor 18. Quantity information is entered. And based on these input information, a predetermined calculation process is performed and the control command by the process result is output to the integrated controller 6 and the brake hydraulic pressure unit 19. A front left wheel wheel cylinder 20, a front right wheel wheel cylinder 21, a rear left wheel wheel cylinder 22, and a rear right wheel wheel cylinder 23 are connected to the brake fluid pressure unit 19. The brake fluid pressure unit 19 and the wheel cylinders 20, 21, 22, and 23 correspond to mechanical braking means.

  The integrated controller 6 manages the energy consumption of the entire vehicle and has a function for running the vehicle with the highest efficiency. The integrated controller 6 performs engine operating point control by a control command to the engine controller 1 during acceleration running or the like. In addition, the motor generator operating point control is performed by a control command to the motor controller 2 at the time of stopping, running, braking, or the like. The integrated controller 6 includes the accelerator opening AP, the vehicle speed VSP, the engine speed Ne, the first motor generator speed N1, and the second motor generator speed N2 from the sensors 7, 8, 9, 10, and 11. Entered. And based on these input information, a predetermined calculation process is performed and the control command by the process result is output to the engine controller 1 and the motor controller 2. FIG. The integrated controller 6 and the engine controller 1, the integrated controller 6 and the motor controller 2, and the integrated controller 6 and the brake controller 5 are connected by bidirectional communication lines 24, 25, and 26, respectively, for information exchange.

Next, driving force performance will be described.
As shown in FIG. 2 (b), the driving force of the hybrid vehicle of the first embodiment includes the engine direct driving force (the driving force obtained by subtracting the generator driving amount from the total engine driving force) and the motor driving force (both motor generators MG1). , Driving force by the sum of MG2). As shown in FIG. 2A, the maximum driving force is configured such that the lower the vehicle speed, the greater the motor driving force. In this way, since the vehicle does not have a transmission and travels by adding the direct driving force of the engine E and the motor driving force that is electrically converted, the full power of the accelerator pedal is fully opened from low speed to high speed from the state of low steady driving power. Until now, it is possible to control the driving force seamlessly in response to the driver's request (torque on demand).
In the hybrid vehicle of the first embodiment, the engine E, the motor generators MG1, MG2, and the left and right front tires are connected without a clutch through the power split mechanism TM. Further, as described above, most of the engine power is converted into electric energy by a generator, and the vehicle is driven by a motor with high output and high response. For this reason, for example, when driving on a slippery road such as an ice burn, when the driving force of the vehicle changes suddenly due to tire slip or tire locking during braking, the power control unit 3 is protected from excessive current. Alternatively, it is necessary to protect parts from the pinion over-rotation of the power split mechanism TM. On the other hand, motor traction control that utilizes the high-output and high-response motor characteristics, developed from the component protection function, detects tire slip instantly, recovers its grip, and runs the vehicle safely. Is adopted.

Next, the braking force performance will be described.
In the hybrid vehicle of the first embodiment, the second motor generator MG2 that is operating as a motor is operated as a generator during the deceleration request operation such as a brake depression operation or an accelerator release operation, whereby the kinetic energy of the vehicle is converted into electric energy. A regenerative braking system is adopted in which the battery 4 is recovered and recovered in the battery 4 and reused.
As shown in Fig. 3 (a), the general regenerative brake cooperative control in this regenerative brake system calculates the required braking force with respect to the brake pedal depression amount, regardless of the magnitude of the required braking force. The required braking force is shared by the regenerative component and the hydraulic component.
In contrast, the regenerative brake cooperative control employed in the hybrid vehicle of the first embodiment calculates the required braking force with respect to the brake pedal depression amount as shown in FIG. 3 (b), and calculates the calculated required braking force. On the other hand, the regenerative brake is given priority, and as long as the regenerative portion can cover it, the regenerative portion is expanded to the maximum without using the hydraulic component. Thereby, especially in a traveling pattern in which acceleration / deceleration is repeated, energy recovery efficiency is high, and energy recovery by regenerative braking is realized up to a lower vehicle speed.

Next, the vehicle mode will be described.
As the vehicle mode in the hybrid vehicle of the first embodiment, as shown in the collinear diagram of FIG. 4, “stop mode”, “start mode”, “engine start mode”, “steady travel mode”, “acceleration mode” Have
In the “stop mode”, as shown in FIG. 4A, the engine E, the generator MG1, and the motor MG2 are stopped. In the “start mode”, as shown in FIG. 4B, the motor MG2 is driven to start. In the “engine start mode”, as shown in FIG. 4 (c), the sun gear S rotates to start the engine E by the generator MG 1 having a function as an engine starter. In the “steady running mode”, as shown in FIG. 4 (d), the vehicle runs mainly with the engine E, and power generation is minimized in order to increase efficiency. In the “acceleration mode”, as shown in FIG. 4 (e), the rotational speed of the engine E is increased and power generation by the generator MG1 is started, and the driving power of the motor MG2 is increased using the electric power and the electric power of the battery 4. In addition, it accelerates.
In reverse running, in the “steady running mode” shown in FIG. 4 (d), if the rotation speed of the generator MG1 is increased while the increase in the rotation speed of the engine E is suppressed, the rotation speed of the motor MG2 becomes negative. Transition and reverse travel can be achieved.

  At the start, the engine E is started by turning the ignition key. When the engine E warms up, the engine E is stopped immediately. At the time of start-up or when the vehicle is lightly loaded down a gentle hill running at a very low speed, the fuel is cut in the region where the engine efficiency is low, and the engine E is stopped and the vehicle is driven by the motor MG2. During normal travel, the driving force of the engine E is driven directly by the power split mechanism TM to the left and right front wheels, while the other drives the generator MG1 and assists the motor MG2. At the time of full open acceleration, power is supplied from the battery 4 and further driving force is added. During the deceleration request operation, the left and right front wheels drive the motor MG2 and act as a generator to perform regenerative power generation. The collected electrical energy is stored in the battery 4. When the charge amount of the battery 4 decreases, the generator MG1 is driven by the engine E and charging is started. When the vehicle is stopped, the engine E is automatically stopped except when the air conditioner is used or when the battery is charged.

Next, the operation will be described.
[Regenerative braking force control processing]
FIG. 5 is a flowchart showing the flow of the regenerative braking force control process executed by the integrated controller 6 according to the first embodiment. Each step will be described below (regenerative braking control means).

In step S1, it is determined whether or not the vehicle is traveling near the junction point. If Yes, the process proceeds to step S5. If No, the process proceeds to step S2.
Here, whether or not the vehicle is traveling in the vicinity of the junction point is determined by whether or not the merged vehicle information is input from the vehicle information collection sensor 29 installed at the junction point such as an expressway in the communication receiver 27 of the own vehicle. If there is no input, it is determined that it is not near the joining point.

  In step S2, following the determination in step S1 that the vehicle is not traveling near the junction point, based on the sensor signal from the inter-vehicle sensor 28, is there an obstacle such as a preceding vehicle or structure in front of the host vehicle? If the answer is Yes, the process proceeds to step S3. If the answer is No, the process proceeds to step S4.

  In step S3, following the determination in step S2 that there is an obstacle ahead of the host vehicle, the vehicle speed of the host vehicle is calculated from the rotation speed information from the second motor generator rotation speed sensor 11, and the inter-vehicle sensor 28 Ascertain the relative vehicle speed of the obstacle ahead of the vehicle detected by, calculate the estimated time to reach the obstacle based on the distance between the vehicle and the obstacle and the relative vehicle speed, and the size of the obstacle ( (Horizontal width) is confirmed, and the process proceeds to step S4 (necessary turning amount estimation means: obstacle arrival time prediction means, obstacle size prediction means).

In step S4, following the calculation of the “estimated arrival time to the obstacle” and the confirmation of “the size of the obstacle” in step S3, “estimated arrival time to the obstacle” and “the size of the obstacle” are set. FIG. 14 compares the “regeneration amount setting map with respect to the predicted time to reach the front obstacle and the size of the obstacle” shown in FIG. 14, and sets the regenerative amount (a value that limits the regenerative amount for obtaining the required braking force), The process proceeds to S8.
In step S4, when the regenerative braking amount is limited in consideration of an obstacle, regenerative cooperative control is performed to increase the hydraulic braking force according to the limiting amount (reduction amount of the regenerative braking amount). Further, in this regenerative cooperative control, when the regenerative braking amount is limited to zero (= regenerative braking is prohibited), the total braking force of the front and rear wheels coincides with the required braking force obtained by the driver's braking operation, and the front and rear The hydraulic braking force of the front and rear wheels is controlled so that the hydraulic braking force distribution ratio of the wheels becomes the ideal distribution ratio (mechanical braking force control means).
In step S4, following the determination in step S2 that there is no obstacle ahead of the host vehicle, the normal braking regeneration amount (regenerative amount for obtaining the required braking force) without restriction is set, and the flow advances to step S8. Transition. In addition, when an obstacle exists in front of the host vehicle and the braking regeneration amount is limited, the normal braking regeneration amount is returned at a determination timing that there is no obstacle in front of the host vehicle.

  In step S5, following the determination that the vehicle is traveling in the vicinity of the merge point in step S1, merge vehicle information (from vehicle information collection sensor 29 installed at a merge point such as a highway in the vehicle's communication receiver 27 ( The vehicle speed and acceleration of the other vehicle that is closest to the vehicle is collected, and the process proceeds to step S6.

In step S6, following the collection of the merged vehicle information in step S5, the merged vehicle information and the vehicle information are collated, and the process proceeds to step S7.
Here, “verification of merged vehicle information and own vehicle information” calculates the time required for the vehicle to reach the position of the vehicle information collection sensor 29 based on the vehicle speed of the vehicle (the vehicle arrival required Time calculation means), based on the vehicle speed and acceleration of the other vehicle, the time required for the other vehicle to reach the position of the vehicle information collection sensor 29 is calculated (time required for other vehicle arrival time calculation means), and the time required for own vehicle arrival This is done by comparing the time required to reach the other vehicle.

In step S7, following the collation of the merged vehicle information and the own vehicle information in step S6, if the time difference between the own vehicle arrival required time and the other vehicle arrival required time is equal to or less than the set value, before reaching the avoidance start point A regeneration amount (a value that limits the regeneration amount for obtaining the required braking force) is set, and the process proceeds to step S8.
Here, the braking regeneration amount at the junction point is set with reference to the braking regeneration amount setting map shown in FIG. The braking regeneration amount setting map shown in FIG. 17 is shorter than the first time difference setting values Δt1, Δt1 ′ when the other vehicle arrives first and the first time difference setting values Δt1, Δt1 ′, and the host vehicle reaches first. The second time difference set value Δt2, Δt2 ′ is determined in advance, and the time difference Δt between the time required to reach the vehicle and the time required to reach the other vehicle is calculated from the first time difference set value Δt1 while traveling near the junction point. In the range up to the 2-hour difference set value Δt2, between the first time-difference set value Δt1 and Δt1 ′, the braking regeneration amount is greatly limited as the time difference approaches zero (Δt = 0), and the second time-difference set value Between Δt2 and Δt2 ′, the regeneration set amount characteristic is such that the braking regeneration amount is largely limited as the time difference approaches zero (Δt = 0). In this braking regenerative amount setting map, the maximum regenerative braking amount limit is set within the range between the first time difference set value Δt1 ′ and the second time difference set value Δt2 ′ including zero time difference, and the regenerative braking force of the front wheels and the rear wheels. The braking force distribution ratio of the front and rear wheels by the hydraulic braking force is defined to be an ideal distribution ratio. It should be noted that the braking regeneration amount set here is canceled when the specified distance β after passing through the merging point is passed (see FIG. 16).

In step S8, following the regeneration amount setting in step S4 or step S7, it is determined whether or not to proceed to the vehicle system end flow. If yes, the process proceeds to the end, and if no, the process returns to step S1. .
That is, when the driver shuts down the vehicle system (for example, detects an ignition OFF signal), this control is terminated, and if the system activation is continued, the process is fed back to step S1.

[Understeering tendency during braking turning]
For example, in a front-wheel drive vehicle such as that of the first embodiment, when regenerative braking is executed only on the front wheels without any restriction during braking turning (particularly on a low μ road), the normal vehicle behavior shown by the solid line in FIG. On the other hand, as shown by the dotted line in FIG. 6, the vehicle behavior deviates from the turning line intended by the driver in the understeer direction. This is due to the following reason.

  First, the front / rear braking force distribution between the front wheel braking force and the rear wheel braking force at the time of braking is the distribution of the front / rear braking force of a general vehicle (a vehicle that does not have a proportioning valve or an electronically controlled braking force distribution system EBD). As shown in FIG. 7, the braking force is distributed back and forth along a linear characteristic that approximates an ideal distribution line for maximizing the braking force, and the braking force is applied to the front and rear wheels as shown in FIG. However, in a hybrid vehicle, if the distribution of braking force front / rear is the ideal braking force distribution, it is necessary to operate the hydraulic brake on the left and right rear wheels that are not connected to the generator, and the regenerative component is deducted from the hydraulic component. Since the remaining amount is obtained, the energy recovery amount is reduced, which is disadvantageous for improving fuel consumption.

  Therefore, in the hybrid vehicle of the first embodiment, as shown in FIG. 9, all the required braking force that can be covered by regeneration is obtained by regeneration, that is, by applying regenerative braking force only to the front wheels, We try to improve fuel efficiency as much as possible. In this case, according to the braking force front / rear distribution characteristics shown in FIG. 7, the braking force distribution of the left and right rear wheels becomes zero, and as shown by the arrows, the rear wheel braking force of a general vehicle is added to the front wheel braking force. The front wheel braking force ratio becomes excessive. Thus, when the front wheel braking force ratio is excessive, the front wheel lock boundary line is approached, and the braking force margin to the front wheel lock boundary line is reduced.

  On the other hand, as shown in FIG. 10, the force that the tire can transmit to the road surface is within a friction circle in which the vector sum of the longitudinal force (braking force) and the lateral force is determined by the road surface μ when braking. It is prescribed. The friction circle draws a large circle when it is a high μ road so that μ = 0.1 and μ = 0.3 are different. However, the friction circle draws a smaller circle as it is a low μ road. In addition, as shown in FIG. 11, the cornering force of the left and right front wheels is lower when the road is low μ than when the road is high μ. That is, in the case of a low μ road, the allowable limit of braking force and lateral force is small, and the cornering force is also low.

  Accordingly, when looking at the vehicle behavior during low μ road braking turning, in the case of turning with a braking force applied along the ideal front-rear distribution, as shown in FIG. 12, the braking force margin during straight braking before entering the turning is shown. Since this margin vector (braking force) can be used for the lateral force, it is possible to turn along the curve curve of the road.

  On the other hand, looking at the vehicle behavior at the time of low μ road braking turning in a hybrid vehicle, the braking force corresponding to the front / rear braking force is covered only by the front wheels, so as shown in FIG. Already there is no braking force margin, even if the rudder is turned, it is difficult to generate lateral force, and the generation of lateral force is small, so the cornering force that defines turning performance during turning decreases, and the vehicle behavior tends to be understeer The turning trajectory of the vehicle deviates from the curve curve intended by the driver.

  Therefore, in a front-wheel drive vehicle, when regenerative braking is performed only on the front wheels without any restriction during braking turning (particularly on a low μ road), the vehicle behavior shows an understeer tendency.

[Regenerative braking amount restriction when avoiding obstacles]
On the other hand, in the regenerative braking control device for a hybrid vehicle according to the first embodiment, when a situation where an obstacle is present in the traveling direction of the host vehicle is detected, the regenerative braking amount for only the front wheels is limited, thereby making the turning characteristic without any sense of incongruity. To avoid obstacles easily.

  First, when the vehicle is not traveling near the merge point and there is no obstacle such as a preceding vehicle or a structure in front of the host vehicle, the flow proceeds from step S1 to step S2 to step S4 in the flowchart of FIG. Thus, in step S4, the normal braking regeneration amount without limitation (regenerative amount for obtaining the required braking force) is set. In the previous control cycle, if the braking regeneration amount is limited based on the determination that there is an obstacle in front of the vehicle, the determination timing that there is no obstacle in front of the vehicle The normal braking regeneration amount is restored.

  Next, when the vehicle is not traveling near the junction point and there is an obstacle such as a preceding vehicle or a structure in front of the host vehicle, step S1 → step S2 → step S3 → step S4 in the flowchart of FIG. It becomes the flow to go to. In this step S3, the predicted arrival time to the obstacle is calculated based on the inter-vehicle distance between the own vehicle and the obstacle and the relative vehicle speed between the own vehicle and the obstacle, and the size (width) of the obstacle is determined. It is confirmed. Then, in step S4, the “estimated arrival time to the obstacle” and “the size of the obstacle” are set as the “estimated arrival time to the front obstacle and the regeneration amount setting map for the size of the obstacle” shown in FIG. And set the regenerative amount (value that limits the regenerative amount to obtain the required braking force), and increase the hydraulic braking force on the rear wheel side according to the limit amount on the front wheel side (reduction amount of regenerative braking amount) Regenerative cooperative control is performed.

Here, in the regeneration amount setting map for the predicted arrival time to the front obstacle and the size of the obstacle shown in FIG. 14, the regeneration amount is smaller (larger limit) as the predicted arrival time to the front obstacle is shorter. In addition, the larger the obstacle, the smaller the regeneration amount (large limit).
That is, it is necessary to avoid the obstacle with a larger turning amount as the predicted time to reach the front obstacle is shorter, and it is necessary to avoid the obstacle with a larger turning amount as the obstacle is larger. From this, it can be said that the “estimated arrival time to the obstacle” and “the size of the obstacle” are information for grasping the turning amount necessary for avoiding the obstacle ahead of the host vehicle. In the first embodiment, based on two pieces of information “estimated arrival time to obstacle” and “size of obstacle”, there is a restriction that increases the amount of decrease in the regenerative braking amount as the required turning amount is estimated to be large. Is going.

  Therefore, for example, when the stopped vehicle existing in the traveling direction of the host vehicle is an obstacle, the regeneration amount of the front wheels is limited from the obstacle recognition point (= avoidance start point) as shown in FIG. Therefore, since the steer characteristic can be shifted to the neutral steer direction from the characteristic of the understeer tendency, even if the turning operation is performed with a normal familiar feeling due to the neutral steer state, the shortage of the actual turning amount with respect to the predicted turning amount can be suppressed to a small amount. The stop vehicle can be easily avoided by the turning operation of the own vehicle.

  Furthermore, when the regenerative amount on the front wheel side is limited in order to avoid obstacles, the hydraulic braking force is increased on the rear wheel side according to the amount of decrease in the regenerative braking force on the front wheel side (= reduced regenerative braking force) Since the regenerative cooperative control is performed, it is possible to prevent a decrease in the total braking force of the entire vehicle while suppressing an understeer tendency and to secure a desired vehicle deceleration.

  In addition, when the regenerative braking amount on the front wheel side is limited to zero (= regenerative braking is prohibited) in order to avoid obstacles, the total braking force of the front and rear wheels becomes the required braking force obtained by the driver's braking operation. Since the hydraulic braking force of the front and rear wheels is controlled so that the hydraulic braking force distribution ratio of the front and rear wheels is equal to the ideal distribution ratio, the total braking force of the entire vehicle is reduced while suppressing the understeer tendency. Compensate and ensure the desired vehicle deceleration.

  Next, when the vehicle is traveling in the vicinity of the junction point, the flow proceeds from step S1 to step S5 to step S6 to step S7 in the flowchart of FIG. In this step S5, in the communication receiver 27 of the own vehicle, the merging vehicle information from the vehicle information collecting sensor 29 installed at the merging point such as an expressway (vehicle speed and acceleration of the other vehicle closest to the own vehicle). In step S6, the combined vehicle information and the own vehicle information are collated by comparing the own vehicle arrival required time and the other vehicle arrival required time. In step S7, the braking regeneration amount setting map at the junction point shown in FIG. 17 is referred to. When the time difference between the own vehicle arrival required time and the other vehicle arrival required time is equal to or less than the set value, before reaching the avoidance start point. Is set to the regenerative amount (a value that limits the regenerative amount for obtaining the required braking force).

Here, the braking regeneration amount setting map at the junction point shown in FIG. 17 is shorter than the first time difference setting values Δt1, Δt1 ′ and the first time difference setting values Δt1, Δt1 ′ when the other vehicle arrives first. The second time difference set value Δt2, Δt2 ′ when the host vehicle arrives first is determined in advance, and the time difference Δt between the host vehicle required travel time and the other vehicle required travel time is the first time while traveling near the junction point. When the time difference setting value Δt1 is within the range from the second time difference setting value Δt2, the braking regeneration amount is greatly limited as the time difference approaches zero (Δt = 0) between the first time difference setting value Δt1 and Δt1 ′. The regenerative set amount characteristic in which the brake regenerative amount is largely limited as the time difference approaches zero (Δt = 0) between the second time difference set values Δt2 and Δt2 ′.
In other words, if another vehicle reaches the merge point first, that is, if there is another vehicle that reaches the merge point earlier than the own vehicle, the other vehicle will be On the other hand, in order to avoid the preceding vehicle, it is not possible to change the course of the preceding vehicle, and it is necessary to make a significant course change by turning in the own vehicle that can monitor the behavior of the preceding vehicle. On the other hand, if the vehicle reaches the merge point first, that is, if there is another vehicle that arrives at the merge point later than the own vehicle, the other vehicle will be In order to avoid the following vehicle as a succeeding vehicle with respect to the own vehicle, the course change by turning in the own vehicle may be small by allowing a course change of the following vehicle having the own vehicle as a preceding vehicle. For this reason, the second time difference setting values Δt2, Δt2 ′ when the host vehicle arrives first are set to a shorter time than the first time difference setting values Δt1, Δt1 ′ when the other vehicle arrives first. .

  Therefore, when there is a possibility of course change (turning) to avoid obstacles at the junction, as a logic to limit the regenerative braking amount of the left and right front wheels based on the deceleration operation before starting obstacle avoidance When the predicted advance control is performed and the turning operation is performed to avoid the obstacle, the understeer tendency of the vehicle is surely suppressed from the start of the turning operation. For this reason, when obstacles are avoided at the merge point, even if the turning operation is performed with a normal familiar feeling due to the neutral steering state, the shortage of the actual turning amount with respect to the predicted turning amount is suppressed, and the turning operation of the own vehicle Obstacles such as a preceding vehicle and a succeeding vehicle can be easily avoided.

  Further, in the regenerative amount setting map at the junction point shown in FIG. 17, the maximum limit amount of the regenerative braking amount is set to the front wheel within the range of the first time difference set value Δt1 ′ and the second time difference set value Δt2 ′ including zero time difference. The braking force distribution ratio of the front and rear wheels by the regenerative braking force and the rear wheel hydraulic braking force is defined to be an ideal distribution ratio. For this reason, when the braking turning operation is performed to avoid the approach to the obstacle at the junction point, the total braking force of the entire vehicle is compensated while reliably suppressing the understeer tendency of the vehicle, and there is no front wheel tip lock. Desired vehicle deceleration can be ensured by the maximum braking force.

  Further, as shown in FIG. 16, the regenerative braking amount limiting control at the merging point is such that the side where the other vehicle enters the merging point where the vehicle information collecting sensor 29 is installed is within the specified distance α. The side where the vehicle and other vehicles join after the merge point where the vehicle information collection sensor 29 is installed is the target of information collection, and information on other vehicles existing within the specified distance β (<specified distance α). It is the target of collection. Therefore, while driving near the merge point, the braking regeneration amount is set at the predicted timing when another vehicle is present within the long specified distance α, whereas the set braking regeneration amount is after passing through the merge point. Will be canceled at an early timing of passing a short prescribed distance β.

Next, the effect will be described.
In the regenerative braking control device for a vehicle according to the first embodiment, the following effects can be obtained.

  (1) In a vehicle provided with regenerative braking control means that performs regenerative braking only on one of the front and rear wheels based on a deceleration request operation, the regenerative braking control means includes an obstacle in the traveling direction of the host vehicle. When the situation is detected, in order to limit the regenerative braking amount for only one of the front and rear wheels, in the situation where there is an obstacle in the traveling direction of the host vehicle, When performing a turning operation to avoid, an obstacle can be easily avoided by a turning characteristic without a sense of incongruity.

  (2) A necessary turning amount estimating means (step S3) for estimating a turning amount necessary for the own vehicle to avoid the obstacle is provided, and the regenerative braking control means (step S4) is the own vehicle for avoiding the obstacle. As the required turning amount is estimated to be large, the amount of decrease in the regenerative braking amount for the front wheels only is limited. Therefore, the larger the required turning amount, the greater the suppression margin for the understeer tendency, and the larger the required turning amount. Regardless, obstacles can be easily avoided.

  (3) The required turning amount estimating means is an obstacle arrival time predicting means (step S3) for predicting an arrival time to an obstacle existing in the traveling direction of the host vehicle, and the regenerative braking control means (step S4). Limits the amount of decrease in the regenerative braking amount as the predicted time to reach an obstacle existing in the direction of travel of the vehicle is shorter, so the shorter the estimated time to reach the obstacle The suppression cost of the understeer tendency increases, and obstacles can be easily avoided regardless of the degree of approach between the vehicle and the obstacle.

  (4) The required turning amount estimating means is an obstacle size predicting means (step S3) for predicting the size of an obstacle existing in the traveling direction of the host vehicle, and the regenerative braking control means (step S4) , In order to limit the amount of decrease in the regenerative braking amount as the obstacle present in the traveling direction of the vehicle is larger, the understeer tendency is reduced as the obstacle (width) becomes larger. Obstacles can be easily avoided regardless of the size.

  (5) A communication receiver 27 is provided for receiving the merged vehicle information emitted from the vehicle information collecting sensor 29 installed at the merge point of the travel path, and the regenerative braking control means is configured to receive the merged vehicle while traveling near the merge point. If the vehicle information is checked against the vehicle information and it is determined in the vehicle that obstacle avoidance is necessary before joining, the obstacle will be blocked at the joining point in order to limit the braking regeneration amount before reaching the avoidance start point. If there is a possibility of avoiding this, an understeer tendency can be reliably suppressed by predictive advance control that limits the braking regeneration amount in advance.

  (6) The communication receiver 27 receives the vehicle speed and acceleration of the other vehicle that is closest to the host vehicle from the vehicle information collecting sensor 29 installed at the junction point as merged vehicle information (step S5). The vehicle arrival time calculation means (step S6) for calculating the vehicle arrival time required for the vehicle to reach the position of the vehicle information collection sensor 29, and the other vehicle arrival time required for the other vehicle to reach the position of the vehicle information collection sensor 29. The other vehicle arrival required time calculating means (step S6) is provided, and the regenerative braking control means (step S7) calculates the difference between the own vehicle arrival required time and the other vehicle arrival required time while traveling in the vicinity of the junction point. If the time difference is less than or equal to the set value, the braking regeneration amount is limited before reaching the avoidance start point, so the possibility of avoiding other vehicles at the merge point is determined by the degree of proximity between the host vehicle and the other vehicle at the merge point. The braking regeneration amount can be appropriately limited according to the possibility of avoidance at the junction point.

  (7) The regenerative braking control means sets the first time difference setting value Δt1 when the other vehicle arrives first and the second time difference setting when the host vehicle arrives earlier than the first time difference setting value Δt1. The value Δt2 is determined in advance, and while traveling near the junction point, the time difference between the time required for arrival at the own vehicle and the time required for arrival at the other vehicle is within the range from the first time difference set value Δt1 to the second time difference set value Δt2. In this case, as the time difference approaches zero, the braking regeneration amount is greatly limited.Therefore, the higher the degree of proximity between the host vehicle and the other vehicle at the merge point, the greater the suppression cost of the understeer tendency. Obstacles can be easily avoided regardless of the level of approach.

  (8) The brake hydraulic unit 19 and the rear wheel cylinders 22 and 23 for generating the hydraulic braking force in the left and right rear wheels that do not perform regenerative braking among the front and rear wheels are provided, and the regenerative braking control means ( Steps S4 and S7) perform regenerative cooperative control to increase the hydraulic braking force according to the limit amount when limiting the regenerative braking amount. Therefore, when limiting the regenerative braking amount, the vehicle suppresses the understeer tendency. It is possible to prevent a decrease in the total braking force.

  (9) The regenerative braking control means (step S7) regulates the maximum amount of regenerative braking so that the braking force distribution ratio of the front and rear wheels by the regenerative braking force and the hydraulic braking force becomes an ideal distribution ratio. While suppressing the understeer tendency, the total braking force of the entire vehicle can be compensated and a desired vehicle deceleration can be ensured.

  (10) When the regenerative braking amount is limited to zero by the brake hydraulic unit 19 and the wheel cylinders 20, 21, 22, 23 that generate the hydraulic braking force on each wheel and the regenerative braking control means, Hydraulic braking force control means (brake controller 5) by regenerative coordination that controls the hydraulic braking force of the front and rear wheels so that the braking force matches the required braking force and the hydraulic braking force distribution ratio of the front and rear wheels becomes the ideal distribution ratio. Thus, it is possible to compensate for the total braking force of the entire vehicle while reliably suppressing the understeer tendency of the vehicle, and to secure a desired vehicle deceleration by the maximum braking force without the front wheel tip lock.

  As described above, the regenerative braking control device for a vehicle according to the present invention has been described based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and the claims relate to each claim. Design changes and additions are allowed without departing from the scope of the invention.

  In the first embodiment, an example of application to a front wheel drive-based vehicle (FF vehicle) is shown. However, the regenerative braking control device of the present invention can also be applied to a rear wheel drive-based vehicle (for example, an FR vehicle). . When applied to a rear-wheel drive based vehicle, steering operation during regenerative braking will tend to oversteer, but limit the amount of regenerative braking and allocate that limit to the hydraulic brakes on the front wheels. Thus, the braking force distribution of the front and rear wheels can be brought close to the ideal distribution, and the oversteer tendency can be suppressed.

  In the first embodiment, as a regenerative braking control means, when a situation where an obstacle exists in the traveling direction of the host vehicle is detected during regenerative braking for only the front wheels, the regenerative braking amount is continuously limited according to the estimation of the required turning amount. An example of setting the regenerative braking amount was shown, but limiting the regenerative braking amount, such as obtaining a correction amount to be reduced and corrected from the required braking force according to the estimation of the required turning amount (regenerative braking with zero regenerative braking amount is prohibited) And the like, and other means may be included as well.

  In the first embodiment, examples of necessary turning amount estimating means include a means for estimating by an estimated arrival time to an obstacle, a means for estimating by the size of the obstacle, and a means for estimating by a difference in arrival time to the junction point. However, in addition to these, for example, estimation of the required turning amount based on the vehicle grade of the preceding vehicle (2WD / 4WD discrimination), estimation of the required turning amount based on the road surface μ, estimation of the required turning amount based on the vehicle behavior of the preceding vehicle, etc. May be performed.

  In the first embodiment, an example of means for obtaining hydraulic braking force by brake hydraulic pressure is shown as mechanical braking means. However, mechanical braking force is obtained by something other than regenerative braking force such as an electric motor brake (EMB). Is also included.

  In the first embodiment, an example of application to a front-wheel drive hybrid vehicle including one engine, two motor generators, and a power split mechanism has been shown. However, the regenerative braking control device of the present invention includes another power unit structure. A vehicle equipped with regenerative braking control means for performing regenerative braking with only one of the front and rear wheels based on a deceleration request operation, such as a hybrid vehicle, electric vehicle, fuel cell vehicle, etc. driven by front wheels or rear wheels Can be applied.

1 is an overall system diagram illustrating a hybrid vehicle to which a regenerative braking control device according to a first embodiment is applied. FIG. 2 is a driving force performance characteristic diagram and a driving force conceptual diagram in a hybrid vehicle to which the regenerative braking control device of the first embodiment is applied. It is a contrast characteristic figure showing the braking force performance by regenerative cooperation in the hybrid car to which the regenerative braking control device of Example 1 was applied. It is an alignment chart which shows each vehicle mode in the hybrid vehicle to which the regenerative braking control apparatus of Example 1 was applied. It is a flowchart which shows the flow of the regenerative braking force control process performed with the integrated controller of Example 1. FIG. It is an image figure showing the understeer phenomenon at the time of braking turning. It is a braking force distribution characteristic diagram showing the distribution before and after the braking force during regenerative cooperation. It is a figure which shows the normal brake state by the ideal front-back distribution of braking force. It is a figure which shows the brake state equivalent to regenerative cooperation (0.2G) in FF vehicle. It is a figure which shows the friction circle showing the force which a tire can take out on the road surface (micro | micron | mu). FIG. 6 is a cornering force characteristic diagram with respect to slip ratios at different road surfaces μ. It is explanatory drawing which shows the turning condition in the normal brake state by the ideal front-back distribution of braking force. It is explanatory drawing which shows the turning condition in the case of showing the understeer tendency at the time of turning in the front-wheel regenerative braking state in FF vehicle. It is a regeneration amount setting map with respect to the estimated time to reach the front obstacle and the size of the obstacle in the first embodiment. It is a figure which shows the condition which avoids the obstruction (stop vehicle) in Example 1 by turning by restrict | limiting the regeneration amount of the own vehicle. It is a merging point schematic plan view which shows an example of the merging point where the vehicle information collection sensor was installed. 3 is a regeneration amount setting map at a merging point in the first embodiment.

Explanation of symbols

E engine
MG1 1st motor generator
MG2 Second motor generator
OS output sprocket
TM power split mechanism 1 engine controller 2 motor controller 3 power control unit 4 battery 5 brake controller 6 integrated controller 7 accelerator opening sensor 8 vehicle speed sensor 9 engine speed sensor 10 first motor generator speed sensor 11 second motor generator speed Sensor 12 Front left wheel speed sensor 13 Front right wheel speed sensor 14 Rear left wheel speed sensor 15 Rear right wheel speed sensor 16 Steering angle sensor 17 Master cylinder pressure sensor 18 Brake stroke sensor 19 Brake fluid pressure unit 20 Front left wheel wheel cylinder 21 Front right wheel wheel cylinder 22 Rear left wheel wheel cylinder 23 Rear right wheel wheel cylinder 24, 25, 26 Two-way communication line 27 Communication receiver (receiving means)
28 Vehicle-to-vehicle sensor 29 Vehicle information collection sensor (vehicle information collection means)

Claims (10)

In a vehicle provided with regenerative braking control means for performing regenerative braking only on one of the front and rear wheels based on a deceleration request operation,
A regenerative braking control device for a vehicle, wherein the regenerative braking control means limits a regenerative braking amount for only one of the front and rear wheels when detecting a situation where an obstacle exists in the traveling direction of the host vehicle. In the regenerative braking control device for a vehicle according to claim 1,
Provide necessary turning amount estimation means to estimate the turning amount necessary for the own vehicle to avoid obstacles,
The regenerative braking control means limits the increase in the amount of decrease in the regenerative braking amount for only one of the front and rear wheels as the necessary turning amount of the vehicle avoiding the obstacle is estimated to be large. Vehicle regenerative braking control device. In the regenerative braking control device for a vehicle according to claim 2,
The required turning amount estimating means is an obstacle arrival time predicting means for predicting an arrival time to an obstacle existing in the traveling direction of the own vehicle,
The regenerative braking control means restricts the reduction amount of the regenerative braking amount to be larger as the predicted time to reach an obstacle existing in the traveling direction of the host vehicle is shorter. apparatus. In the regenerative braking control device for a vehicle according to claim 2,
The required turning amount estimation means is an obstacle size prediction means for predicting the size of an obstacle present in the traveling direction of the host vehicle,
The regenerative braking control device according to claim 1, wherein the regenerative braking control means performs a restriction to increase a reduction amount of the regenerative braking amount as an obstacle present in the traveling direction of the host vehicle increases. In the regenerative braking control device for a vehicle according to any one of claims 1 to 4,
A receiving means for receiving the merged vehicle information emitted from the vehicle information collecting means installed at the merge point of the travel path;
The regenerative braking control means collates the merged vehicle information with the vehicle information while traveling near the merge point, and reaches the avoidance start point when it is determined in the own vehicle that obstacle avoidance is necessary before the merge. A regenerative braking control device for a vehicle, wherein the braking regeneration amount is limited before starting. In the regenerative braking control device for a vehicle according to claim 5,
The receiving means receives the vehicle speed and acceleration of the other vehicle that comes closest to the host vehicle from the vehicle information collecting means installed at the meeting point as merged vehicle information,
The own vehicle arrival time calculation means for calculating the own vehicle arrival time required for the host vehicle to reach the position of the vehicle information collection means, and the other vehicle arrival time required for the other vehicle to reach the position of the vehicle information collection means Vehicle arrival time calculation means,
The regenerative braking control means limits the braking regeneration amount before reaching the avoidance start point when the time difference between the time required for arrival at the own vehicle and the time required for arrival at the other vehicle is equal to or less than a set value while traveling near the junction point. A regenerative braking control device for a vehicle. In the regenerative braking control device for a vehicle according to claim 6,
The regenerative braking control means predetermines a first time difference set value when the other vehicle arrives first and a second time difference set value when the host vehicle arrives earlier than the first time difference set value. If the time difference between the time required to reach the vehicle and the time required to reach the other vehicle is within the range from the first time difference set value to the second time difference set value while driving near the junction, braking is performed as the time difference approaches zero. A regenerative braking control device for a vehicle, wherein the regenerative amount is largely limited. In the regenerative braking control device for a vehicle according to any one of claims 1 to 7,
Mechanical braking means for generating mechanical braking force on the other left and right wheels that do not perform regenerative braking among the front and rear wheels;
When the regenerative braking control means limits the regenerative braking amount, the regenerative braking control device performs regenerative cooperative control that increases the mechanical braking force according to the restriction amount. In the regenerative braking control device for a vehicle according to claim 8,
The regenerative braking control means regulates the maximum amount of regenerative braking so that the front-rear wheel braking force distribution ratio by the regenerative braking force and the mechanical braking force is an ideal distribution ratio. Control device. In the regenerative braking control device for a vehicle according to any one of claims 1 to 7,
Mechanical braking means for generating mechanical braking force on each wheel;
When the regenerative braking control means limits the regenerative braking amount to zero, the front and rear wheels are set so that the total braking force of the front and rear wheels matches the required braking force and the mechanical braking force distribution ratio of the front and rear wheels becomes an ideal distribution ratio. Mechanical braking force control means by regenerative cooperation for controlling the mechanical braking force of
A regenerative braking control device for a vehicle, comprising:

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