JP2006217677A - Regenerative brake controller of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a regenerative brake controller of vehicle in which regenerative brake control for sustaining stability in behavior of a vehicle can be achieved while suppressing the amount of regenerative braking exceeding a required level under such conditions as nose dive occurs due to regenerative braking. <P>SOLUTION: A vehicle having a means for performing regenerative braking with the right and left wheels in only one of front and rear wheels based on deceleration request operation is provided with a means for estimating the amount of nose dive due to regenerative braking (step S2-step S8). Upon detecting such conditions as nose dive occurs, the regenerative brake control means limits the amount of regenerative braking for suppressing variation in behavior characteristics of the vehicle due to the amount of nose dive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a regenerative braking control device for a vehicle (such as a hybrid vehicle or an electric vehicle) provided with regenerative braking control means for performing regenerative braking with only one of the front and rear wheels based on a deceleration request operation.

Conventionally, in a system including a drive wheel capable of hydraulic braking and regenerative braking and a driven wheel capable of hydraulic braking, by smoothly switching from the regeneration priority mode to the normal mode (ideal braking force distribution: regenerative cut mode) Therefore, sudden changes in braking force are prevented (see, for example, Patent Document 1).
JP-A-5-161209

  However, in the above-described conventional regenerative braking control device, although regenerative braking is restricted during turning or on a low μ road surface, it is not a technique that takes into account the amount of nose dive due to the road surface gradient, so there is a road surface gradient. Carrying out regenerative braking in some situations could worsen vehicle behavior in some cases. Specifically, with a front-wheel drive vehicle that uses the front wheels as regenerative braking wheels, if regenerative braking of the front wheels is performed 100% while turning downhill, the vehicle's center of gravity moves to the front wheels, resulting in a large nose dive amount. When nose dive is added to the side of the braking force, the cornering power is reduced, and the steering characteristic tends to be understeered.

  The present invention has been made paying attention to the above problem, and achieves regenerative braking control that maintains vehicle behavior stability while suppressing the limit of the amount of regenerative braking more than necessary in a situation where nose diving occurs due to regenerative braking. An object of the present invention is to provide a regenerative braking control device for a vehicle.

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,
Nose dive amount estimating means for estimating the nose dive amount due to regenerative braking is provided,
The regenerative braking control means limits the regenerative braking amount that suppresses a change in vehicle behavior characteristics due to the amount of the nose dive amount when detecting a situation where nose dive occurs.

  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 nose dive occurs, the regenerative braking amount for suppressing the vehicle behavior characteristic change due to the magnitude of the nose dive amount is reduced. Restrictions are made. For example, when turning downhill on a front-wheel drive vehicle having a front wheel as a regenerative braking wheel, the vehicle tends to be understeered due to excessive wheel load on the front wheel due to road gradient. In this case, when a situation in which nose diving occurs is detected, the regenerative braking amount of the front wheels is limited, so that the deviation of the braking force distribution is reduced and the understeer tendency is suppressed. On the other hand, in a situation where nose dives rarely occur when traveling on an uphill road, the vehicle does not tend to be understeered, thereby reducing the need to limit the amount of regenerative braking of the front wheels and increasing the amount of energy recovered. . As a result, in a situation where nose diving occurs due to regenerative braking, it is possible to achieve regenerative braking control that maintains vehicle behavior stability while suppressing the restriction of the regenerative braking amount more than necessary.

  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 receives input information from an accelerator opening sensor 7, a vehicle speed sensor 8, an engine speed sensor 9, a first motor generator speed sensor 10, and a second motor generator speed sensor 11. Brought about.

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

  In step S1, the “nose dive estimation amount (= gradient determination amount)” stored in the integrated controller 6 itself at the time of system startup is reset, and the process proceeds to step S2.

In step S2, following reset of the nose dive estimation amount in step S1, it is determined whether or not power running is in progress. If Yes (power running), the process proceeds to step S3. If No (regeneration), step S3 is performed. The process proceeds to S6.
When the process proceeds to step S2 for the first time after resetting the nose dive estimated amount, whether or not the sensor command values of the accelerator opening sensor 7 and the brake stroke sensor 18 are zero, and the battery 4 is charged (regeneration). Check for current.

  In step S3, following the determination that power running is being performed in step S2, the sensor command value from the accelerator opening sensor 7 is confirmed, and the process proceeds to step S4.

  In step S4, following the accelerator opening confirmation in step S3, the acceleration is confirmed by the change in the rotational speed of the second motor generator MG2, and the process proceeds to step S5. This acceleration confirmation may be confirmed by a change in vehicle speed from the vehicle speed sensor 8.

In step S5, following the acceleration confirmation in step S4, the "accelerator sensor command value" collected in step S3 and the "acceleration" collected in step S4 are substituted into the "acceleration nose dive amount estimation map" shown in FIG. Then, the nose dive amount due to regenerative braking is estimated, stored as “current nose dive estimated amount”, and the process proceeds to step S9.
Here, as shown in FIG. 6, the “acceleration nose dive amount estimation map” has an accelerator sensor command value on the horizontal axis, a nose dive amount on the vertical axis, and a right-proportional characteristic that rises to the right depending on the magnitude of acceleration. A plurality of lines are drawn, the characteristic line is specified by the “acceleration” collected in step S4, and the nose dive amount at the point where the characteristic line specified by the “accelerator sensor command value” collected in step S3 intersects is read and regenerated. Estimate the amount of nose dive during braking.
That is, the nose dive amount at the time of regenerative braking has a relationship of descending slope nose dive amount> flat road nose dive amount> uphill nose dive amount, and the nose dive amount can be estimated from the road surface gradient. On the other hand, even if the road surface gradient during power running is the same accelerator opening, the acceleration is greater when the road gradient is a downhill road than the acceleration on a flat road, and conversely, the road gradient is flatter when the road gradient is an uphill road. It can be estimated by the fact that the acceleration is smaller than the road.
Therefore, in the first embodiment, during power running, the road surface gradient amount is detected based on the difference between the acceleration estimated value corresponding to the accelerator operation amount and the actual acceleration, and the nose dive amount during regenerative braking as the road surface gradient amount indicates a downhill gradient. Is estimated to be large.

  In step S6, following the determination in step S2 that regeneration is in progress, the sensor command value from the brake stroke sensor 18 is confirmed, and the process proceeds to step S7.

  In step S7, following the brake operation amount confirmation in step S6, the deceleration is confirmed by the change in the rotation speed of the second motor generator MG2, and the process proceeds to step S8. This deceleration confirmation may be confirmed by a change in vehicle speed from the vehicle speed sensor 8.

In step S8, following the deceleration check in step S7, the "brake sensor command value" collected in step S6 and the "deceleration" collected in step S7 are shown in the "deceleration nose dive amount estimation map" shown in FIG. Substituting and collating, the nose dive amount due to regenerative braking is estimated, stored as “current nose dive estimated amount”, and the process proceeds to step S9.
Here, the “deceleration nose dive amount estimation map”, as shown in FIG. 7, takes the brake sensor command value on the horizontal axis, the nose dive amount on the vertical axis, and is inversely proportional to the right depending on the magnitude of deceleration. A plurality of characteristic lines are drawn. The characteristic line is specified by the "deceleration" collected in step S7, and the nose dive amount at the point where the characteristic line specified by the "brake sensor command value" collected in step S6 intersects is read. Estimate the nose dive amount during regenerative braking.
That is, the nose dive amount at the time of regenerative braking has a relationship of descending slope nose dive amount> flat road nose dive amount> uphill nose dive amount, and the nose dive amount can be estimated from the road surface gradient. On the other hand, even if the road surface gradient during regeneration is the same brake operation amount, the lower the road gradient, the lower the deceleration compared to the deceleration on a flat road, and conversely, the road gradient is an uphill road. It can be estimated that the deceleration increases as compared with the flat road.
Therefore, in the first embodiment, during regeneration, the road surface gradient amount is detected based on the difference between the estimated deceleration value corresponding to the brake operation amount and the actual deceleration, and the nose during regenerative braking increases as the road surface gradient amount shows a downhill gradient. It is estimated that the amount of dive is large.

  In step S9, following the estimation of the nose dive amount in step S5 or step S8, the stored “previous nose dive estimated amount” is checked in order to apply the control based on the increase / decrease change in the nose dive estimation amount, and in step S10 Migrate to

In step S10, following the previous nose dive estimated amount confirmation in step S9, a nose dive change amount obtained by subtracting the “previous nose dive estimated amount” from the “current nose dive estimated amount” collected in step S5 or step S8 is calculated. Then, this nose dive change amount is substituted and collated with the “first gain setting map according to the nose dive change amount” shown in FIG. 8, the first gain is determined, and the process proceeds to step S11.
Here, as shown in FIG. 8, the “first gain setting map according to the nose dive change amount” has the first gain = 1 when the nose dive change amount is zero, and increases on the increasing side of the nose dive change amount. The first gain is given as a larger value (> 1) as the amount is larger, and the first gain is given as a smaller value (<1) as the amount of decrease is larger on the decrease side of the nose dive change amount.

In step S11, following the setting of the first gain based on the nose dive change amount in step S10, the “current nose dive estimation amount” collected in step S5 or step S8 is shown in FIG. 9 according to the “nose dive estimation amount”. Substitution checking is performed on the “second gain setting map” to determine the second gain, and the process proceeds to step S12.
Here, as shown in FIG. 9, the “second gain setting map according to the nose dive estimation amount” has a second gain = 1 when the nose dive estimation amount is equivalent to a flat road, and the nose dive estimation amount is a flat road. The larger the nose dive estimation amount on the larger downhill side, the larger the second gain is given (> 1), and the smaller the nose dive estimation amount on the uphill side where the nose dive estimation amount is smaller than the flat road, the smaller the second gain. It is given as a small value (<1).

In step S12, following the setting of the second gain by the nose dive estimation amount in step S11, the first gain by the nose dive change amount in step S10, and the second gain by the nose dive estimation amount in step S11, The set gain for correcting the regeneration amount is multiplied to determine the regeneration amount distribution ratio at least one of the turning amount and the estimated road surface μ by the “regeneration-hydraulic braking amount distribution map” shown in FIG. The regeneration amount distribution ratio is set by multiplying the regeneration amount distribution ratio by the setting gain for correcting the regeneration amount, and considering the nose dive, and the process proceeds to step S13.
Here, the “regeneration-hydraulic braking amount distribution map” shown in FIG. 10 is a regenerative braking amount restriction map based on a flat road, and the front wheel regeneration 100 is performed in a region where the turning amount or 1 / road surface μ is equal to or less than the first set value a1. In the region where the turning amount or 1 / road surface μ is between the first setting value a1 and the second setting value a2, the turning amount or 1 / In a region where the road surface μ is equal to or larger than the second set value a2, the ratio is fixed at a ratio at which an ideal braking force distribution is obtained.
That is, when limiting the regenerative braking amount of the front wheel, the hydraulic braking force of the rear wheel is increased according to this limit amount (the increase / decrease amount of the regeneration amount is distributed to the hydraulic brake), and the maximum limit amount of the regenerative braking amount is set. The regenerative cooperative control is performed so that the braking force distribution ratio between the front and rear wheels by the regenerative braking force and the hydraulic braking force is an ideal distribution ratio.
For example, as shown in the dotted line characteristic of FIG. 10, in the region where the turning amount or 1 / road surface μ is equal to or larger than the second set value a2, when limiting the regenerative braking amount of the front wheels to zero (regenerative braking prohibited) The required braking force may be obtained only by the hydraulic braking force, and the brake fluid pressure may be controlled so that the braking force distribution ratio between the front wheel hydraulic braking force and the rear wheel hydraulic braking force becomes an ideal distribution ratio.

  In step S13, following the setting of the regeneration amount by gain application in step S12, it is determined whether or not to move to the system end sequence. If Yes, the process ends. If No, the process returns to step S2. . That is, when the driver shuts down the vehicle system (for example, when an ignition OFF signal is detected), this control is terminated. If the system activation is continued, the process is fed back to step S2.

[Regenerative limiting action when traveling on a slope]
Limits on regenerative braking during cornering and low μ road travel were controlled based on flat roads, regardless of road slope, but regenerative braking depends on whether the road slope is downhill, flat, or uphill. The vehicle behavior is different when the amount is limited.

  For example, in a front-wheel drive vehicle with front wheels as regenerative braking wheels, if regenerative braking of 100% front wheels is performed while turning downhill, the center of gravity of the vehicle moves to the front wheels, resulting in a large nose dive amount. . In addition, a nose dive is added to the side of the braking force to increase the braking force transmitted from the tire to the road surface, and the lateral force is allowed to be applied to the friction circle by the tire by increasing the braking force (specified by the size of the road surface μ). If it protrudes from the above, the cornering power decreases, and the steering characteristic tends to be understeered.

  On the other hand, if 100% front wheel regenerative braking is performed while turning on an uphill road with a front-wheel drive vehicle, both the rear wheel side movement of the vehicle center of gravity position on the uphill road and the front wheel side movement of the vehicle center of gravity position on regenerative braking are both As a result, the position of the center of gravity of the vehicle is less displaced from the reference position, and the amount of nose dive generation is small. As long as the front wheel braking force and the front wheel lateral force are within the friction circle allowed by the tire, the cornering power will not decrease and the neutral steering characteristic will be maintained. be able to.

  In other words, when turning downhill where a large amount of nose dive occurs, limiting the regenerative braking amount is effective from the standpoint of stabilizing the vehicle behavior, but when turning uphill where the amount of nose dive generation is small, It can be said that the necessity of limiting the regenerative braking amount is small.

  On the other hand, in the first embodiment, by taking into account the magnitude of the nose dive amount that is generated or will be generated by regenerative braking, an appropriate amount of energy recovery and stable vehicle behavior can be achieved. Limiting control of the regenerative braking amount is possible. That is, during power running, in the flowchart of FIG. 5, the flow proceeds from step S1, step S2, step S3, step S4, and step S5. In step S5, the “accelerator sensor command value” collected in step S3 and step The “acceleration” collected in S4 is substituted into the “acceleration nose dive amount estimation map” shown in FIG. 6 and collated to estimate the nose dive amount due to regenerative braking, and stored as “current nose dive estimated amount”.

  During regeneration, the flow proceeds from step S1 to step S2 to step S6 to step S7 to step S8 in the flowchart of FIG. 5. In step S8, “brake sensor command value” collected in step S6 and step S7. The collected “deceleration” is substituted into the “deceleration nose dive amount estimation map” shown in FIG. 7 and collated, the nose dive amount due to regenerative braking is estimated, and stored as “current nose dive estimated amount”.

  From step S5 or step S8, the process proceeds from step S9 to step S10 to step S11 to step S12. In step S9, the stored “previous nose dive estimation amount” is checked. The nose dive change amount obtained by subtracting the “previous nose dive estimate amount” from the “nose dive estimate amount” is calculated, and this nose dive change amount is converted into the “first gain setting map according to the nose dive change amount” shown in FIG. Substitution verification is performed to determine the first gain. In step S11, the “current nose dive estimation amount” is substituted and collated with the “second gain setting map according to the nose dive estimation amount” shown in FIG. 9 to determine the second gain. In step S12, the first gain and the second gain are multiplied to calculate a set gain for regenerative amount correction, and the turning amount and the estimated road surface μ are calculated based on the “regeneration-hydraulic braking amount distribution map” shown in FIG. At least one of them determines a regeneration amount distribution ratio, and multiplies the determined regeneration amount distribution ratio by a setting gain for regeneration amount correction to set a regeneration amount distribution ratio in consideration of nose dives.

  For example, when the regeneration amount distribution ratio determined only by the “regeneration-hydraulic braking amount distribution map” shown in FIG. 10 is 70% for the left and right front wheels and 30% for the left and right rear wheels (FIG. 10). A) will be described as an example. If the nose dive amount is large and the second gain is greater than 1 as a result of downhill determination, as shown in FIG. 10A ′, the regenerative amount distribution ratio shifts to the side that restricts the regenerative amount, and the left and right front wheels The regenerative braking force is 50% and the braking force distribution is 50% for the left and right rear wheels. Therefore, when the nose dive amount is large, the steer characteristic shows an understeer tendency as the nose dive amount is increased. Therefore, by restricting the regenerative amount, the understeer tendency due to the deviation of the regenerative braking force from the front wheels is alleviated. On the other hand, when the nose dive amount is small and the second gain is a value smaller than 1 due to the uphill determination, as shown in FIG. 10A ", the regenerative amount distribution ratio shifts to a side that relaxes the regenerative amount limit, The left and right front wheels have a regenerative braking force of 100%, and the left and right rear wheels have a hydraulic braking force of 0% .Therefore, when the nose dive amount is small and the vehicle behavior is not deteriorated, the regenerative amount is not limited. “No more regenerative amount restriction than necessary” → “Energy recovery efficiency improvement” → “Fuel efficiency improvement” is realized.

  Further, a case where the traveling path repeats uphill and downhill will be described. At the time of transition from uphill to downhill, the nose dive estimated amount changes in the direction of increasing, so the first gain becomes a value greater than 1, and the regenerative amount is temporarily limited during the transitional transition from uphill to downhill To be strengthened. On the other hand, at the time of transition from downhill to uphill, the nose dive estimated amount changes in a decreasing direction, so that the first gain becomes a value smaller than 1, and the amount of regeneration is limited during the transitional transition from downhill to uphill. Temporarily relaxed. Furthermore, when the road slope changes in the direction of increasing or decreasing the nose dive estimation amount on an uphill or downhill slope, the regeneration limit is temporarily strengthened or relaxed during the transitional period of the road slope. The

  Further, in the first embodiment, the nose dive amount is estimated not only during regenerative braking but also during power running, so that the first control cycle that has entered regeneration when switching from power running to regenerative braking by braking operation is performed. The regenerative braking amount can be limited using the nose dive estimated amount at the time of powering immediately before regeneration. That is, when switching from power running to regeneration, an appropriate braking force distribution can be set immediately.

  Next, the regenerative braking amount limiting control action on the traveling road that repeats uphill and downhill will be described with reference to the time chart shown in FIG. The road changes as follows: climbing road from time t1 → gentle downhill road from time t1 to t2 → sudden downhill road from time t2 to t3 → climbing road after time t3, regenerating from time t1 to time t4 A zone.

  The uphill road up to time t1 is an uphill road with a constant slope, and since the nose dive estimation amount is smaller than the nose dive amount equivalent to a flat road, the first gain is 1 and the second gain is less than 1. The set gain for this is a constant value less than 1, and the regeneration-hydraulic braking force distribution is set to 100% regeneration.

  On the gentle downhill from time t1 to t2, the nose dive change amount increases during the transitional transition from the uphill road, and the nose dive estimate is equivalent to a flat road due to the gentle downhill road. When the value is larger, the first gain> 1 and the second gain> 1, and the set gain for correcting the regeneration amount temporarily becomes a large value of 1 or more. And if it enters into a gentle downhill road, it becomes a gentle downhill road with a constant gradient, so that the first gain = 1 and the second gain> 1, and the set gain for correcting the regeneration amount is a constant value of 1 or more. Is done. Therefore, the regeneration-hydraulic braking force distribution is set to about 60% regeneration with good response immediately upon entering the regeneration.

  On the steeply descending slope from time t2 to t3, the nose dive change amount increases during the transitional transition from the gentle descending slope, and the nose dive estimated amount is equivalent to a flat road due to the steeply descending slope. When the amount is larger than the amount, the first gain> 1 and the second gain> 1, and the set gain for the regeneration amount correction temporarily becomes a large value of 1 or more. When entering a steeply descending slope, the slope becomes a steeply descending slope, the first gain = 1 and the second gain> 1, and the set gain for correcting the regeneration amount is a constant value of 1 or more. Is done. Therefore, the regenerative-hydraulic braking force distribution is set to about 80% regenerative regeneration (ideal distribution of front and rear wheels) immediately with good response when entering a steep downhill road from a gentle downhill road.

  On the uphill road from time t3 to time t4, the nose dive change amount decreases on the transition transition period from the steeply descending slope road, and the nose dive estimated amount is equivalent to a flat road due to the uphill road. By being smaller, the first gain <1 and the second gain <1, and the set gain for correcting the regeneration amount temporarily becomes a small value less than 1. And if it goes into an uphill road, it will become an uphill road of a fixed gradient, so that the first gain = 1 and the second gain <1, and the set gain for correcting the regeneration amount is a constant value less than 1. . Therefore, the regenerative-hydraulic braking force distribution is set to about 80% regenerative regeneration (ideal distribution of front and rear wheels) immediately with good response when entering the uphill road from the steeply descending slope.

  On the uphill road after time t4, the uphill road has a constant slope, and since the nose dive estimation amount is smaller than the nose dive amount equivalent to a flat road, the first gain is 1 and the second gain is less than 1. The set gain for this is a constant value less than 1, and the regeneration-hydraulic braking force distribution is set to 100% regeneration.

  Therefore, among the regenerative-hydraulic braking force distribution characteristic lines in FIG. 11, the thin line characteristic is a characteristic when correction is not performed based on the nose dive amount, and the thick line characteristic is a characteristic when correction is performed based on the nose dive amount. . When both characteristics are compared, hatched portion B from time t1 to time t3 is a portion where the limit of the regenerative braking amount is increased in order to stabilize the vehicle behavior characteristic of the understeer tendency, and the hatched portion from time t3 to time t4 C is a portion in which the restriction on the regenerative braking amount is relaxed in order to improve energy recovery efficiency, that is, to improve fuel efficiency.

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) Nose dive amount estimating means for estimating a nose dive amount due to regenerative braking in a vehicle having regenerative braking control means for performing regenerative braking only on one of the front and rear wheels based on a deceleration request operation (steps S2 to S2) Step S8) is provided, and when the regenerative braking control means detects the occurrence of nose dive, the nose due to regenerative braking is performed to limit the regenerative braking amount that suppresses the change in vehicle behavior characteristics due to the magnitude of the nose dive amount. In a situation where a dive occurs, it is possible to achieve regenerative braking control that maintains vehicle behavior stability while suppressing the regenerative braking amount limit more than necessary.

  (2) Since the nose dive amount estimating means estimates the nose dive amount due to regenerative braking based on the detected value of the road surface gradient amount, the road surface gradient corresponding to the nose dive amount during regenerative braking is used to accurately perform regenerative braking. The amount of nose dive can be estimated.

  (3) The nose dive amount estimating means detects a road surface gradient amount based on a difference between an acceleration estimated value according to an accelerator operation amount and an actual acceleration during power running, and a deceleration estimated value according to a brake operation amount during regeneration. In order to estimate the amount of nose dive during regenerative braking as the road surface gradient amount indicates a downhill gradient, a new sensor for detecting the road surface gradient is added. In addition, the road surface gradient amount can be detected in both the power running / regeneration mode, and an appropriate regenerative braking amount can be immediately set from the control cycle at the start of regenerative braking when shifting from power running to regeneration.

  (4) The regenerative braking control means limits the regenerative braking amount to be smaller as the nose dive amount is estimated to be larger. It is possible to suppress the tendency and improve the running / steering stability, and to increase the energy recovery amount by continuing the regenerative braking at the time of climbing where the figure dive amount is small.

  (5) The brake hydraulic unit 19 and the wheel cylinders 22 and 23 that generate hydraulic braking force on the left and right rear wheels that do not perform regenerative braking are provided, and the regenerative braking control means restricts the regenerative braking amount of the front wheels. The hydraulic braking force of the rear wheels is increased according to this limit amount, and the maximum limit amount of the regenerative braking amount is set so that the braking force distribution ratio of the front and rear wheels by the regenerative braking force and the hydraulic braking force becomes the ideal distribution ratio. Regenerative cooperative control as defined in the above is performed, so that it is possible to obtain a total braking force that satisfies the required braking force when the regenerative braking amount is limited, and to brake with stable vehicle behavior due to high braking performance when the maximum regenerative braking amount is limited. be able to.

  (6) The regenerative braking control means increases the regenerative braking amount as the nose dive estimation amount is on the uphill road side with respect to the reference regenerative braking amount determined by the “regenerative-hydraulic braking amount distribution map” based on the flat road. In order to perform correction to reduce the regenerative braking amount as it is closer to the downhill road (steps S11 and S12), simple correction processing without preparing a plurality of maps by using correction based on a flat road Thus, the regenerative braking amount limiting control according to the nose dive estimation amount can be achieved.

  (7) When the nose dive estimated amount changes, the regenerative braking control means corrects the regenerative braking amount more restrictively for the increase side change in the nose dive estimated amount, and reduces the nose dive estimated amount. In order to perform a correction that further relaxes the restriction on the regenerative braking amount with respect to the side change (step S10), the vehicle behavior is stable and the energy recovery amount is improved with good response even on a road where the road surface gradient changes, such as a course with severe undulations. Coexistence with increase can be achieved.

  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 application example to a front wheel drive base vehicle (FF vehicle) is shown, but the regenerative braking control device of the present invention can also be applied to a rear wheel drive base vehicle (for example, an FR vehicle). In the case of this FR vehicle, the oversteer tendency can be suppressed by limiting the regeneration amount of the rear wheel when the nose dive amount is large.

  In the first embodiment, as a regenerative braking control means, when detecting a situation where nose dive occurs, regenerative braking is performed by correction by gain setting in consideration of a nose dive amount {≈gradient (uphill / downhill)} on the basis of a flat road. Although the example of determining the braking amount is shown, for example, the regenerative braking amount is adjusted by moving the “regenerative-hydraulic braking amount distribution map” based on the flat road in the horizontal axis (turning amount, 1 / road surface μ) direction based on the nose dive amount. It may be decided. In addition, when the vehicle behavior characteristic changes depending on the nose dive amount, the regenerative braking amount that suppresses the vehicle behavior characteristic change is limited, and the yaw moment control (VDC control) by the braking force difference that actively avoids the vehicle behavior characteristic change is performed. May be adopted. In short, the regenerative braking control means is included in the present invention as long as the regenerative braking control means limits the regenerative braking amount that suppresses the change in the vehicle behavior characteristic due to the size of the nose dive amount when detecting the occurrence of the nose dive.

  In the first embodiment, the road surface gradient amount is detected based on the difference between the acceleration estimated value corresponding to the accelerator operation amount and the actual acceleration during power running, and the deceleration estimated value and the actual deceleration depending on the brake operation amount during regeneration. Although an example of detection based on the difference is shown, a road surface inclination sensor or the like may be installed, a road surface gradient amount may be determined based on sensor information, or road surface gradient information may be obtained from a navigation system or infrastructure.

  In the first embodiment, as a “regenerative-hydraulic braking amount distribution map” for determining the reference regenerative braking force, as shown in FIG. 10, at least one of the turning amount and 1 / road surface μ is set from the 100% regeneration mode to the ideal distribution mode. The example in which the step is changed steplessly according to the above is shown. For example, the regeneration 100% mode and the ideal distribution mode are switched in two steps with at least one set value of the turning amount and 1 / road surface μ as a boundary. Furthermore, the regenerative 100% mode to the ideal distribution mode may be switched in a plurality of stages according to at least one of the turning amount and 1 / road surface μ.

  In the first and second embodiments, as the mechanical braking means, an example of means for obtaining the hydraulic braking force by the brake hydraulic pressure is shown. However, the mechanical braking force is obtained by other than the regenerative braking force such as an electric motor brake (EMB). Even 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 control process performed with the integrated controller of Example 1. FIG. It is a figure which shows the nose dive amount estimation map at the time of acceleration used in the regenerative braking control process of Example 1. It is a figure which shows the nose dive amount estimation map at the time of deceleration used in the regenerative braking control process of Example 1. It is a figure which shows the 1st gain setting map with respect to the nose dive variation | change_quantity which is the difference of this time and the previous nose dive estimated amount used in the regenerative braking control process of Example 1. FIG. It is a figure which shows the 2nd gain setting map with respect to this nose dive estimated amount used in the regenerative braking control process of Example 1. FIG. It is a figure which shows the "regenerative-hydraulic braking amount distribution map" on the basis of the flat road used in regenerative braking control processing. 6 is a time chart showing characteristics of a nose dive amount (≈gradient amount), a set gain, and regenerative-hydraulic braking force distribution for explaining a regenerative braking control action in a course with severe undulations in Example 1;

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

Claims (7)

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,
Nose dive amount estimating means for estimating the nose dive amount due to regenerative braking is provided,
A regenerative braking control device for a vehicle according to claim 1, wherein the regenerative braking control means limits a regenerative braking amount that suppresses a change in vehicle behavior characteristic due to a nose dive amount when detecting a situation in which a nose dive occurs. In the regenerative braking control device for a vehicle according to claim 1,
The regenerative braking control device for a vehicle, wherein the nose dive amount estimating means estimates a nose dive amount due to regenerative braking based on a detected value of a road surface gradient amount. In the regenerative braking control device for a vehicle according to claim 2,
The nose dive amount estimating means detects a road surface gradient amount based on a difference between an acceleration estimated value corresponding to an accelerator operation amount and an actual acceleration during power running, and a deceleration estimated value and an actual decrease corresponding to a brake operation amount during regeneration. A regenerative braking control device for a vehicle, wherein a road surface gradient amount is detected based on a difference from speed, and a nose dive amount during regenerative braking is estimated to be larger as the road surface gradient amount indicates a downhill gradient. In the regenerative braking control device for a vehicle according to any one of claims 1 to 3,
The regenerative braking control device for a vehicle is characterized in that the regenerative braking control means performs a restriction to reduce the regenerative braking amount as the nose dive amount is estimated to be large. In the regenerative braking control device for a vehicle according to any one of claims 1 to 4,
Mechanical braking means for generating mechanical braking force on the other left and right wheels that do not perform regenerative braking at least among the front and rear wheels;
When the regenerative braking control means limits the regenerative braking amount of one of the front and rear wheels, the regenerative braking control means increases the mechanical braking force of the other of the front and rear wheels according to the limiting amount, and sets the maximum regenerative braking amount limit. A regenerative braking control device for a vehicle, which performs regenerative cooperative control that regulates the braking force distribution ratio of the front and rear wheels by the regenerative braking force and the mechanical braking force to be an ideal distribution ratio. In the regenerative braking control device for a vehicle according to claim 5,
The regenerative braking control means performs correction to increase the regenerative braking amount as the nose dive estimation amount is on the uphill side with respect to the reference regenerative braking amount determined by the regenerative braking amount restriction map based on the flat road, and the downhill side The regenerative braking control device for a vehicle is characterized in that the regenerative braking amount is corrected so as to be smaller. In the regenerative braking control device for a vehicle according to claim 6,
When the nose dive estimated amount changes, the regenerative braking control means performs a correction for further strengthening the restriction of the regenerative braking amount for the increase side change of the nose dive estimated amount, and reduces the nose dive estimated amount to the decreasing side change. On the other hand, a regenerative braking control device for a vehicle, wherein correction for further relaxing the restriction on the amount of regenerative braking is performed.

Images