JP7666563B2 - Braking control device and braking control method - Google Patents

Description

Applicable to Article 30, Paragraph 2 of the Patent Act. Nationwide sales have begun. (Sales date: September 18, 2023)

The present invention relates to a braking control device and a braking control method for controlling regenerative braking.

In vehicles equipped with regenerative brakes, when the battery is fully charged, the vehicle may not be able to be sufficiently decelerated by the regenerative brakes. Patent Document 1 proposes controlling the brake modulator so that a frictional braking force equivalent to engine braking is applied to each wheel when the driver releases the accelerator pedal when the battery is fully charged.

JP 2019-137312 A

When the vehicle is automatically traveling so as to maintain a constant distance from the vehicle ahead, the driver may not release the accelerator. In the invention described in Patent Document 1, if the battery becomes fully charged during such automatic traveling, the vehicle cannot be sufficiently decelerated by regenerative braking, and the vehicle may approach the vehicle ahead and suddenly brake. This may cause the driver to feel fear.

The present invention has been made in consideration of these points, and aims to provide a braking control device or a braking control method that can prevent a vehicle from approaching too closely to a vehicle ahead while the vehicle is autonomously traveling.

The brake control device of the first aspect of the present invention is a brake control device that controls regenerative braking based on the distance between the vehicle and a vehicle ahead, and includes a memory unit that stores multiple identification information corresponding to the magnitude of the regenerative braking force generated, an acquisition unit that acquires the remaining battery charge of a battery mounted on the vehicle, an identification unit that identifies the necessary braking force required to decelerate the vehicle based on the distance, a selection unit that selects one of the identification information from one or more identification information corresponding to the regenerative braking force that can be output by the regenerative brake in the state of the remaining battery charge, which is identified from the multiple identification information stored in the memory unit based on the acquired remaining battery charge, and a brake control unit that compensates for the insufficiency of the regenerative braking force corresponding to the identification information selected by the selection unit relative to the necessary braking force with a brake other than the regenerative brake.

The selection unit may identify a possible regenerative force for identifying the regenerative braking force that can be output based on the remaining battery charge, identify the one or more identification information such that the regenerative braking force corresponding to the identified identification information is smaller than a maximum value of the regenerative braking force corresponding to the identified possible regenerative force, and select one of the identification information from the one or more identified identification information.

The selection unit may identify a possible regenerative force for identifying the regenerative braking force that can be output based on the remaining battery charge, identify a first identification information on the condition that the identified possible regenerative force is less than a first threshold value, and identify a second identification information corresponding to the regenerative braking force that is greater than the regenerative braking force corresponding to the first identification information on the condition that the possible regenerative force is equal to or greater than the first threshold value.

The braking control device may further include a regenerative control unit that generates the regenerative braking force corresponding to the identification information selected by the selection unit, and when the maximum value of the regenerative braking force corresponding to the possible regenerative force is less than the smallest regenerative braking force among the regenerative braking forces corresponding to the multiple identification information stored in the memory unit, generates the maximum regenerative braking force that can be generated at the time when the maximum value of the regenerative braking force corresponding to the possible regenerative force is less than the smallest regenerative braking force among the regenerative braking forces corresponding to the multiple identification information stored in the memory unit.

The selection unit may select one of the one or more pieces of identification information based on the required braking force. The selection unit may select, from among the one or more pieces of identification information, the identification information corresponding to the smallest regenerative braking force such that the regenerative braking force corresponding to the selected identification information is equal to or greater than the required braking force.

The selection unit may select the identification information corresponding to the maximum regenerative braking force when the regenerative braking force corresponding to all of the identified identification information is less than the required braking force. The selection unit may select a first identification information from the one or more identification information when the required braking force becomes equal to or greater than the first reference value from a value less than a first reference value, and may not select the first identification information from the one or more identification information when the required braking force becomes less than a second reference value that is smaller than the first reference value after selecting the first identification information.

The braking control device may further include a regenerative control unit that, when the selection unit selects first identification information, regeneratively charges the battery so that the charging current for charging the battery has a first current value, and, when the selection unit selects second identification information corresponding to the regenerative braking force that is greater than the regenerative braking force corresponding to the first identification information, regeneratively charges the battery so that the charging current has a second current value that is greater than the first current value. The selection unit may select one of the one or more identification information corresponding to the regenerative braking force that changes depending on the rotation speed of a motor mounted on the vehicle.

The braking control method of the second aspect of the present invention is a braking control method executed by a computer that controls regenerative braking based on the distance between the vehicle and a vehicle ahead, and includes the steps of: acquiring the remaining battery charge of a battery mounted on the vehicle; determining the necessary braking force required to decelerate the vehicle based on the distance; referring to a storage unit that stores a plurality of pieces of identification information corresponding to the magnitude of the regenerative braking force to be generated, selecting one of the pieces of identification information corresponding to the regenerative braking force that can be output by the regenerative brake in the state of the remaining battery charge, which is identified from the plurality of pieces of identification information stored in the storage unit based on the acquired remaining battery charge; and compensating for the insufficiency of the regenerative braking force corresponding to the selected identification information relative to the necessary braking force with a brake other than the regenerative brake.

The braking control device of the third aspect of the present invention includes a determination unit that determines the necessary braking force required to decelerate the vehicle based on the distance between the vehicle and a vehicle ahead, a regenerative control unit that controls the regenerative brake with a regenerative braking force selected based on the remaining battery charge of the vehicle from among a plurality of stepped regenerative braking forces that the regenerative brake can output, and a braking control unit that controls the friction brake so that the friction brake outputs a braking force that is insufficient for the required braking force when the selected regenerative braking force is insufficient for the required braking force.

The braking control method of the fourth aspect of the present invention includes the steps of: determining the braking force required to decelerate the vehicle based on the distance between the vehicle and a vehicle ahead, which are executed by a computer; controlling the regenerative brake with a regenerative braking force selected based on the remaining battery charge of the vehicle from among a plurality of stepped regenerative braking forces that the regenerative brake can output; and controlling the friction brake so that the friction brake outputs a braking force that is insufficient for the required braking force when the selected regenerative braking force is insufficient for the required braking force.

The present invention has the effect of preventing a vehicle from approaching too closely to a vehicle ahead while the vehicle is autonomously traveling.

1 shows an overview of a host vehicle equipped with a brake control device according to an embodiment. The configuration of the host vehicle is shown. 4 is a schematic diagram showing the relationship between the remaining battery charge and the available regenerative power when the motor is operating at a certain rotation speed. FIG. 13 shows an example of a time change in the required braking force determined by the determination unit and a gradual on/off change in the regenerative brake. 13 shows an example of a time change in the required braking force determined by the determination unit and a gradual on/off change in the regenerative brake. 13 shows an example of a time change in the required braking force determined by the determination unit and a gradual on/off change in the regenerative brake. 4 is a flowchart showing a processing procedure for regenerative braking operation by a braking control device. 8 is a flowchart showing details of the braking process in FIG. 7 .

[Vehicle Overview]
1 shows an overview of a host vehicle 100 equipped with a brake control device 1 according to the present embodiment. The host vehicle 100 is, for example, a commercial vehicle such as a truck. The host vehicle 100 travels so as to maintain a constant distance from a vehicle 200 ahead by using an adaptive cruise control (ACC).

The braking control device 1 is, for example, an ECU (Electronic Control Unit). The braking control device 1 controls regenerative braking based on the distance between the host vehicle 100 and the vehicle ahead 200. First, the braking control device 1 determines the braking force required to decelerate the host vehicle based on the distance to the vehicle ahead 200. The braking control device 1 determines information indicating the remaining battery charge of the battery mounted on the host vehicle 100. The information indicating the remaining battery charge is, for example, SOC (State Of Charge, charging rate).

The memory unit of the brake control device 1 stores multiple pieces of identification information each corresponding to a different magnitude of regenerative braking force. The identification information is assumed to be information including a numerical value corresponding to the magnitude of the regenerative braking force, such as "first regenerative stage," "second regenerative stage," and "third regenerative stage." Each piece of identification information is assumed to be information indicating one of multiple regenerative braking forces that generate different regenerative braking forces in stages. Note that the identification information may be information in other formats.

The brake control device 1 identifies one or more pieces of identification information that correspond to the regenerative braking force that can be output by the regenerative brake with the current remaining battery charge, from among the multiple pieces of identification information stored in the memory unit. The brake control device 1 selects one of the one or more pieces of identification information based on the identified required braking force.

The brake control device 1 generates regenerative braking force by notifying the regenerative control unit that generates the regenerative braking force of the selected identification information. If the generated regenerative braking force is insufficient for the required braking force, the brake control device 1 compensates for the insufficient braking force by using brakes other than the regenerative brakes.

In this way, when the regenerative braking does not work sufficiently due to insufficient electrical capacity that can be charged to the battery, the brake control device 1 can compensate for the insufficient regenerative braking force due to the regenerative braking force compared to the required braking force by using brakes other than the regenerative braking force. Therefore, the brake control device 1 can prevent the host vehicle 100 from getting too close to the vehicle 200 in front, thereby preventing the driver from feeling fear. In addition, the brake control device 1 can generate multiple regenerative braking forces corresponding to multiple pieces of identification information, making it easy to generate regenerative braking forces of a magnitude appropriate to the situation of the host vehicle 100.

[Configuration of Vehicle 100]
2 shows the configuration of the host vehicle 100. The host vehicle 100 includes a braking control device 1, a vehicle speed sensor 2, a distance sensor 3, a voltage sensor 4, a battery 5, a motor 6, and a friction brake 7. The braking control device 1 includes a storage unit 11 and a control unit 12. The control unit 12 includes an acquisition unit 121, an identification unit 122, a selection unit 123, a regeneration control unit 124, and a braking control unit 125.

The vehicle speed sensor 2 detects the relative vehicle speed Vm of the host vehicle 100 with respect to the vehicle ahead 200. The relative vehicle speed Vm can be detected by various known methods. The vehicle speed sensor 2 inputs the measured relative vehicle speed Vm to the acquisition unit 121. The distance sensor 3 is, for example, a millimeter wave radar. The distance sensor 3 measures the distance L between the host vehicle 100 and the vehicle ahead 200. The distance sensor 3 inputs the measured distance L to the acquisition unit 121.

The voltage sensor 4 measures the output voltage of the battery 5 mounted on the vehicle 100. The voltage sensor 4 inputs information indicating the output voltage to the acquisition unit 121.

The battery 5 is a power storage device that supplies the motor 6 with driving power for driving the motor 6. The battery 5 can also be charged with regenerative power generated by the motor 6 when the motor 6 performs a regenerative operation. The battery 5 may be fixed to the vehicle 100, or may be mounted so as to be detachable from the vehicle 100.

The motor 6 is mounted on the host vehicle 100. The motor 6 generates a propulsive force for propelling the host vehicle 100. The motor 6 also operates as a regenerative brake, generating electricity to generate a regenerative braking force. The friction brake 7 generates a braking force that decelerates the host vehicle 100 by frictional force.

The storage unit 11 is composed of, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory). The storage unit 11 stores a program to be executed by the control unit 12. The storage unit 11 stores a plurality of pieces of identification information corresponding to the magnitude of the regenerative braking force to be generated. For example, the plurality of pieces of identification information are stored in the storage unit 11 in association with any value of the regenerative braking force. This identification information is referenced by the selection unit 123 for the purpose of controlling the braking force by the regenerative brake in stages. The storage unit 11 stores a table that associates a possible regenerative force P for specifying the regenerative braking force with a maximum value MAX of the regenerative braking force. This table is referenced when the selection unit 123 specifies the maximum value MAX that can be output as the regenerative braking force at the battery remaining capacity V and motor rotation speed M at that time.

The memory unit 11 stores braking force data that associates the distance L from the vehicle 100 to the vehicle ahead 200, the relative vehicle speed Vm, and the required braking force Pw. The braking force data is referenced when the identification unit 122 identifies the required braking force Pw. With this braking force data, if the distance L is the same, the greater the relative vehicle speed Vm, the greater the required braking force Pw. Also, if the relative vehicle speed Vm is the same, the shorter the distance L, the greater the required braking force.

The control unit 12 is, for example, a processor mounted on the ECU. The control unit 12 executes the programs stored in the memory unit 11 to function as an acquisition unit 121, an identification unit 122, a selection unit 123, a regeneration control unit 124, and a braking control unit 125.

The acquisition unit 121 acquires various types of information. The acquisition unit 121 acquires information indicating the distance L between the host vehicle 100 and the vehicle ahead 200 from the distance sensor 3. The acquisition unit 121 acquires the relative vehicle speed Vm of the host vehicle 100 with respect to the vehicle ahead 200 from the vehicle speed sensor 2.

The acquisition unit 121 acquires the remaining battery charge V of the battery 5 mounted on the vehicle 100. In the example of FIG. 2, the acquisition unit 121 acquires the output voltage of the battery 5 measured by the voltage sensor 4. The acquisition unit 121 determines the remaining battery charge V of the battery 5 based on the acquired output voltage. The acquisition unit 121 acquires the motor rotation speed M from the motor 6. The acquisition unit 121 outputs the acquired rotation speed M to the selection unit 123.

Furthermore, the acquisition unit 121 outputs information indicating the distance L between the host vehicle 100 and the forward vehicle 200 to the identification unit 122 and the selection unit 123. The acquisition unit 121 outputs information indicating the remaining battery charge V of the battery 5 mounted on the host vehicle 100 and information indicating the acquired relative vehicle speed Vm to the selection unit 123.

The determination unit 122 determines the braking force required to decelerate the vehicle 100 based on the distance L between the vehicle 100 and the vehicle ahead 200. For example, the determination unit 122 determines the braking force Pw required to maintain the distance between the vehicle 100 and the vehicle ahead 200 at or above a predetermined distance based on the distance L and the relative vehicle speed Vm. The predetermined distance is, for example, a distance specified in advance by the driver.

First, the identification unit 122 reads out braking force data that associates the distance L, the relative vehicle speed Vm, and the required braking force Pw from the memory unit 11. The identification unit 122 refers to the read braking force data and identifies the required braking force Pw that is associated in the braking force data with the distance L and the relative vehicle speed Vm acquired by the acquisition unit 121. The identification unit 122 outputs the identified required braking force Pw to the selection unit 123.

[Select Identification Information]
In order to control the regenerative brake in a stepwise manner, the selection unit 123 identifies one or more pieces of identification information corresponding to one or more selectable regenerative braking forces from among the multiple pieces of identification information stored in the storage unit 11. The regenerative braking forces corresponding to the one or more pieces of identification information vary, for example, according to the motor rotation speed M. Before identifying the identification information, the selection unit 123 calculates in advance a value of the regenerative braking force corresponding to each piece of identification information based on the motor rotation speed M acquired by the acquisition unit 121, and identifies one or more pieces of identification information after the calculation. Based on the battery remaining capacity V, the selection unit 123 identifies one or more pieces of identification information selectable as the regenerative braking force that can be output by the regenerative brake in this state of the battery remaining capacity.

The selection unit 123 identifies a possible regenerative force P for identifying the regenerative braking force that can be output by the regenerative brake based on the remaining battery charge so that the selection unit 123 can select identification information corresponding to the regenerative braking force that can be output. For example, the possible regenerative force P is the ratio of the current braking force that can be generated by the regenerative brake to the maximum braking force generated by the regenerative brake. When the remaining battery charge V is relatively large, there is not enough free capacity for further charging the battery, so the possible regenerative force P becomes relatively small. Since the identification information corresponds to the regenerative braking force output by the regenerative brake, the selection unit 123 can be said to select a specific regenerative braking force based on the remaining battery charge V from one or more stepped regenerative braking forces that can be output by the regenerative brake.

Figure 3 is a schematic diagram showing the relationship between the remaining battery charge V and the possible regenerative power P when the motor 6 is operating at a certain rotation speed. The horizontal axis shows the remaining battery charge V. The vertical axis shows the possible regenerative power P. When the remaining battery charge V is equal to or less than a predetermined value (Vth0), the generated power can be charged to the battery 5 even when the regenerative brake is operating at the maximum regenerative braking force. Therefore, since the regenerative brake can be operated at the maximum regenerative braking force, the possible regenerative power P is the maximum value Pmax (e.g., 100%).

In addition, if the remaining battery charge V is greater than a predetermined value Vth0, the power generated when the regenerative brake operates at the maximum regenerative braking force cannot be charged to the battery 5. Therefore, the regenerative braking force that the regenerative brake can generate is smaller than the maximum regenerative braking force. At this time, the possible regenerative force is smaller than the maximum value Pmax.

Note that in FIG. 3, for the sake of simplicity, the relationship between the remaining battery charge V and the possible regenerative power P is shown linearly, but this is not limiting.

In addition, as described below, the higher the motor rotation speed M, the greater the potential regenerative power P generated by regenerative braking, so the relationship between the remaining battery power V and the potential regenerative power P shown in FIG. 3 changes depending on the motor rotation speed M. For this reason, the selection unit 123 may determine the potential regenerative power P based on the motor rotation speed M in addition to the remaining battery power V.

The selection unit 123 identifies the maximum value MAX of the regenerative braking force corresponding to the identified possible regenerative force P. The maximum value MAX of the regenerative braking force is the regenerative braking force generated when the regenerative brake is operated to the maximum extent under the conditions of the battery remaining capacity V and the motor rotation speed M at that time. For example, the selection unit 123 reads out from the storage unit 11 a table that associates the possible regenerative force P with the maximum value MAX of the regenerative braking force. The selection unit 123 refers to the read out table and identifies the maximum value MAX of the regenerative braking force associated with the identified possible regenerative force P. The selection unit 123 identifies one or more pieces of identification information such that the regenerative braking force corresponding to the identified identification information is smaller than the maximum value MAX of the identified regenerative braking force.

The selection unit 123 selects one piece of identification information from the one or more pieces of identification information identified. At this time, the selection unit 123 selects one piece of identification information based on the required braking force Pw identified by the identification unit 122.

For example, the selection unit 123 selects, from among the one or more pieces of identified identification information, the identification information corresponding to the minimum regenerative braking force at which the regenerative braking force corresponding to the selected identification information is equal to or greater than the required braking force Pw. For example, when the required braking force Pw changes from less than a first reference value to equal to or greater than the first reference value, the selection unit 123 selects the identification information "first stage of regeneration" (corresponding to the first identification information). At this time, the first stage of regeneration by the regenerative brake is switched from off to on. In this way, the selection unit 123 can select the identification information so as to generate the minimum necessary regenerative braking force. On the other hand, when the regenerative braking forces corresponding to all of the identified identification information are less than the required braking force Pw, the selection unit 123 selects the identification information corresponding to the identified maximum regenerative braking force.

The regenerative control unit 124 causes the motor 6 to generate a regenerative braking force corresponding to the identification information selected by the selection unit 123. For example, when the selection unit 123 selects the first identification information, the regenerative control unit 124 performs regenerative charging so that the charging current for charging the battery 5 becomes a first current value. When the selection unit 123 selects the second identification information corresponding to a regenerative braking force greater than the regenerative braking force corresponding to the first identification information, the regenerative control unit 124 performs regenerative charging so that the charging current for charging the battery 5 becomes a second current value. The second current value is greater than the first current value. In this way, the regenerative control unit 124 changes the regenerative power generated by the motor 6 by increasing or decreasing the charging current for charging the battery 5. Therefore, the regenerative control unit 124 can adjust the regenerative braking force when the motor 6 operates as a regenerative brake.

When the maximum value MAX of the regenerative braking force corresponding to the possible regenerative power P is less than the smallest regenerative braking force among the regenerative braking forces corresponding to the multiple identification information stored in the memory unit 11, the regenerative control unit 124 generates the maximum regenerative braking force that can be generated at that time. In this way, the regenerative control unit 124 can suppress an increase in fuel efficiency by generating an appropriate regenerative braking force. Also, when the maximum value MAX of the regenerative braking force corresponding to the possible regenerative power P is less than the smallest regenerative braking force among the regenerative braking forces corresponding to the multiple identification information stored in the memory unit 11, the regenerative control unit 124 does not need to operate the regenerative brake. In this way, the regenerative control unit 124 can suppress overcharging of the battery 5.

The braking control unit 125 decelerates the host vehicle 100 by using brakes other than the regenerative brakes. In the example of FIG. 2, the brakes other than the regenerative brakes are friction brakes 7. The brakes other than the regenerative brakes may be retard brakes, or the friction brakes 7 and retard brakes may be used in combination. The braking control unit 125 identifies an insufficient braking force where the regenerative braking force corresponding to the identification information selected by the selection unit 123 is insufficient for the required braking force Pw. The braking control unit 125 compensates for the insufficient braking force by brakes other than the regenerative brakes. The braking control unit 125 may generate a braking force equal to or greater than the insufficient braking force by brakes other than the regenerative brakes, or may generate a braking force smaller than the insufficient braking force.

[Example of control of regenerative brake and friction brake 7]
4 to 6 show examples of the time change of the necessary braking force Pw determined by the determination unit 122 and the stepwise on/off change of the regenerative brake. The horizontal axis of FIG. 4 indicates time. The first graph from the top of FIG. 4 shows the time change of the necessary braking force Pw determined by the determination unit 122. The vertical axis of this graph shows the necessary braking force Pw. Since the braking force acts in the direction opposite to the traveling direction of the host vehicle 100, the necessary braking force Pw shows a value lower than 0 in the first graph from the top of FIG. 4, and the larger the absolute value of the necessary braking force Pw, the lower the necessary braking force Pw shows. The second to fourth graphs from the top of FIG. 4 show the output state of the regenerative braking force by the regenerative brake in three stages corresponding to the three identification information "first regeneration stage", "second regeneration stage" and "third regeneration stage". The fifth graph from the top of FIG. 4 shows the output state of the braking force by the friction brake 7.

In the first graph from the top of Figure 4, the required braking force Pw increases and then decreases. The maximum value MAX of the regenerative braking force corresponding to the possible regenerative force P identified by the selection unit 123 is shown by a horizontal solid line in Figure 4. In the example of Figure 4, the maximum value MAX of the regenerative braking force corresponding to the possible regenerative force P is greater than any of the regenerative braking forces corresponding to the three identification information "1st regeneration stage," "2nd regeneration stage," and "3rd regeneration stage," and the selection unit 123 identifies these three identification information as selectable identification information.

The selection unit 123 selects the identification information by comparing the required braking force Pw with thresholds corresponding to the three pieces of identification information identified. As shown on the left side of FIG. 4, when the required braking force Pw is smaller than any of the thresholds corresponding to the first to third stages of regeneration, the selection unit 123 does not select any of the identification information. At this time, the first to third stages of regeneration are all in an off state.

The selection unit 123 selects the identification information "first regeneration stage" when the required braking force Pw becomes greater than the threshold value corresponding to the second regeneration stage (the first reference value in FIG. 4). At this time, as shown in the second graph from the top of FIG. 4 for the first regeneration stage, the first regeneration stage of the regenerative brake is switched from off to on, and the regenerative braking force T1 corresponding to the identification information "first regeneration stage" is output by the regenerative control unit 124.

The selection unit 123 selects the identification information "second stage of regeneration" when the required braking force Pw becomes greater than the threshold value corresponding to the second stage of regeneration. At this time, as shown in the graph of the second stage of regeneration, the third from the top in Figure 4, the second stage of regeneration of the regenerative brake is switched from off to on, and the regenerative braking force T2 corresponding to the second stage of regeneration is output by the regenerative control unit 124. Similarly, the selection unit 123 selects the identification information "third stage of regeneration" when the required braking force Pw becomes greater than the threshold value corresponding to the third stage of regeneration.

In the fifth graph from the top of FIG. 4, the selection unit 123 instructs the braking control unit 125 to switch the friction brake 7 from off to on at the timing when the required braking force becomes greater than the regenerative braking force corresponding to the identification information "third stage regeneration" selected by the selection unit 123. At this time, the braking control unit 125 uses the friction brake 7 to compensate for the insufficient braking force, which is the insufficiency of the regenerative braking force corresponding to the identification information "third stage regeneration" relative to the required braking force Pw.

Next, the operation when the regenerative brake is turned off will be described. The selection unit 123 instructs the braking control unit 125 to switch the friction brake 7 from on to off at the timing when the required braking force becomes smaller than the regenerative braking force corresponding to the selection identification information "third stage regeneration" by a predetermined value or more. The predetermined value is set to prevent the friction brake 7 from being frequently and repeatedly switched on and off.

The selection unit 123 deselects the selected identification information and stops the generation of regenerative braking force after the required braking force becomes smaller than the required braking force Pw at the time when each identification information was selected. As an example, when the required braking force Pw becomes less than a second reference value after selecting the identification information "first stage of regeneration", the selection unit 123 changes the identification information "first stage of regeneration" from a selected state to a deselected state. The second reference value is smaller than the first reference value. At this time, the first stage of regeneration by regenerative braking is switched from on to off.

In this way, the first reference value at which the first stage of regeneration of the regenerative brake switches from off to on and the second reference value at which the first stage of regeneration of the regenerative brake switches from on to off are different, so that when the required braking force fluctuates, it is possible to prevent the identification information from switching frequently and the regenerative braking force from increasing or decreasing frequently. Therefore, the selection unit 123 can prevent the ride comfort of the host vehicle 100 from being impaired.

As shown by the solid horizontal line in FIG. 5, the maximum value MAX of the regenerative braking force corresponding to the possible regenerative force P identified by the selection unit 123 is equal to or greater than the regenerative braking force T2 corresponding to the identification information "second stage of regeneration," but is less than the regenerative braking force T3 corresponding to the identification information "third stage of regeneration."

In the example of FIG. 5, the selection unit 123 identifies two identification information items, "regeneration stage 1" and "regeneration stage 2", as selectable identification information, and does not identify the identification information "regeneration stage 3" as selectable identification information. As in FIG. 4, the selection unit 123 selects the identification information "regeneration stage 1" at the timing when the required braking force Pw becomes greater than the first reference value corresponding to the regeneration stage 2. At this time, the regeneration stage 1 of the regenerative brake is switched from off to on.

The selection unit 123 selects the identification information "second stage of regeneration" at the same timing as in FIG. 4, but does not select the identification information "third stage of regeneration." Therefore, as shown in the fourth graph from the top of FIG. 5 for the third stage of regeneration, the third stage of regeneration of the regenerative brake is maintained off, and the regenerative braking force T3 corresponding to the identification information "third stage of regeneration" is not output by the regenerative control unit 124.

In the fifth graph from the top of FIG. 5, the selection unit 123 instructs the braking control unit 125 to switch the friction brake 7 from off to on at the timing when the required braking force becomes greater than the regenerative braking force T2 corresponding to the identification information "second stage of regeneration" selected by the selection unit 123. Since the regenerative braking force T2 corresponding to the identification information "second stage of regeneration" is smaller than the regenerative braking force T3 corresponding to the identification information "third stage of regeneration", the braking control unit 125 activates the friction brake 7 at an earlier timing than in FIG. 4.

As shown by the horizontal solid line in FIG. 6, the maximum value MAX of the regenerative braking force corresponding to the possible regenerative force P identified by the selection unit 123 is equal to or greater than the regenerative braking force T1 corresponding to the identification information "first regeneration stage", but is less than the regenerative braking force T2 corresponding to the identification information "second regeneration stage". In the example of FIG. 6, the selection unit 123 identifies the identification information "first regeneration stage" as selectable identification information, and does not identify the identification information "second regeneration stage" and "third regeneration stage" as selectable identification information. The selection unit 123 selects the identification information "first regeneration stage" at the same timing as in FIG. 4, but does not select the identification information "second regeneration stage" and "third regeneration stage".

For this reason, as shown in the graph for the second regeneration stage, which is the third from the top in FIG. 6, the second regeneration stage of the regenerative brake is maintained off, and the regenerative braking force T2 corresponding to the second regeneration stage is not output by the regenerative control unit 124. Similarly, as shown in the graph for the third regeneration stage, which is the fourth from the top in FIG. 6, the third regeneration stage of the regenerative brake is maintained off, and the regenerative braking force corresponding to the third regeneration stage is not output by the regenerative control unit 124.

As described above, an example has been described in which the selection unit 123 identifies the maximum value MAX of the regenerative braking force corresponding to the possible regenerative force P, and identifies one or more pieces of identification information such that the regenerative braking force corresponding to the identification information is smaller than the identified maximum value MAX of the regenerative braking force. However, the present invention is not limited to the example in which the selection unit 123 identifies the maximum value MAX of the regenerative braking force corresponding to the possible regenerative force P. The selection unit 123 may identify selectable identification information by comparing the possible regenerative force P with a threshold value corresponding to the identification information.

For example, the selection unit 123 identifies the identification information "first regeneration stage" (corresponding to the first identification information) on the condition that the identified possible regenerative force P is less than a first threshold value. The first threshold value changes, for example, according to the motor rotation speed M. The selection unit 123 identifies the identification information "second regeneration stage" (corresponding to the second identification information) on the condition that the identified possible regenerative force P is equal to or greater than the first threshold value. The identification information "second regeneration stage" is identification information corresponding to a regenerative braking force T2 that is greater than the regenerative braking force T1 corresponding to the identification information "first regeneration stage".

[Regenerative braking operation procedure]
7 is a flowchart showing a processing procedure for regenerative braking operation by the brake control device 1. This processing procedure is started, for example, during automatic driving by ACC of the host vehicle 100. First, the acquisition unit 121 acquires information indicating the distance L between the host vehicle 100 and the preceding vehicle 200 from the distance sensor 3, and acquires information indicating the relative vehicle speed Vm of the host vehicle 100 with respect to the preceding vehicle 200 from the vehicle speed sensor 2 (S101).

The determination unit 122 determines the necessary braking force Pw for maintaining the distance between the vehicle 100 and the vehicle ahead 200 at a predetermined distance or more based on the distance L between the vehicle 100 and the vehicle ahead 200 and the relative vehicle speed Vm (S102). The acquisition unit 121 determines whether the necessary braking force Pw determined by the determination unit 122 is greater than 0 (S103). When the acquisition unit 121 determines that the determined necessary braking force Pw is greater than 0 (YES in S103), it acquires the remaining battery charge V (S104). The acquisition unit 121 acquires the motor rotation speed M (S105).

The selection unit 123 determines the possible regenerative power P based on the determined remaining battery charge V and motor rotation speed M (S106). The regenerative control unit 124 and the braking control unit 125 execute the braking process (S107).

The braking control unit 125 determines whether the vehicle 100 has ended the automatic driving (S108). If the braking control unit 125 determines that the vehicle 100 has ended the automatic driving (Yes in S108), the processing ends.

When the acquisition unit 121 determines in the determination of S103 that the required braking force Pw identified is 0 (No in S103), the process proceeds to the determination of S108. When the braking control unit 125 determines in the determination of S108 that the vehicle 100 has not ended the automatic driving (No in S108), the process returns to S101.

Figure 8 is a flowchart showing details of the braking process (S107) in Figure 7. First, the selection unit 123 identifies the maximum value MAX of the regenerative braking force corresponding to the identified possible regenerative force P. The selection unit 123 determines whether the identified maximum value MAX of the regenerative braking force is equal to or greater than the regenerative braking force T2 corresponding to the regenerative brake identification information "second stage of regeneration" (S201). When the selection unit 123 determines that the maximum value MAX of the regenerative braking force corresponding to the identified possible regenerative force P is equal to or greater than the regenerative braking force T2 (Yes in S201), it determines whether the maximum value MAX of the regenerative braking force corresponding to the identified possible regenerative force P is less than the regenerative braking force T3 corresponding to the identification information "third stage of regeneration" (S202).

When the selection unit 123 determines that the maximum value MAX of the regenerative braking force corresponding to the identified possible regenerative force P is less than the regenerative braking force T3 corresponding to the identification information "third regenerative stage" (Yes in S202), it identifies the identification information "first regenerative stage" and "second regenerative stage" (S203). From among the identified identification information, the selection unit 123 selects the identification information corresponding to the smallest regenerative braking force whose corresponding regenerative braking force is equal to or greater than the required braking force Pw identified by the identification unit 122 (S204). The regenerative control unit 124 outputs the regenerative braking force corresponding to the selected identification information by the regenerative brake (S205).

The braking control unit 125 determines whether the regenerative braking force corresponding to the selected identification information is less than the required braking force Pw (S206). If the regenerative braking force corresponding to the selected identification information is less than the required braking force Pw (Yes in S206), the braking control unit 125 causes the friction brake 7 to generate a braking force obtained by subtracting the regenerative braking force corresponding to the selected identification information from the required braking force Pw (S207), and ends the process.

When the selection unit 123 determines that the maximum value MAX of the regenerative braking force corresponding to the possible regenerative force P identified in the determination of S201 is less than the regenerative braking force T2 corresponding to the identification information "second regeneration stage" (No in S201), it determines whether the maximum value MAX of the regenerative braking force corresponding to the identified possible regenerative force P is equal to or greater than the regenerative braking force T1 corresponding to the identification information "first regeneration stage" (S208). When the maximum value MAX of the regenerative braking force corresponding to the possible regenerative force is equal to or greater than the regenerative braking force T1 corresponding to the identification information "first regeneration stage" (Yes in S208), the selection unit 123 identifies the identification information "first regeneration stage" (S209) and proceeds to the processing of S204.

If the maximum value MAX of the regenerative braking force corresponding to the possible regenerative force P identified in the judgment of S208 is less than the regenerative braking force T1 corresponding to the identification information "first regenerative stage" (No in S208), the selection unit 123 outputs the maximum regenerative braking force that can be output to the motor 6 (S210) and proceeds to the judgment of S206. If the selection unit 123 determines that the maximum value MAX of the regenerative braking force corresponding to the possible regenerative force P identified in the judgment of S202 is equal to or greater than the regenerative braking force T3 corresponding to the identification information "third regenerative stage" (No in S202), it identifies the identification information "first regenerative stage", "second regenerative stage", and "third regenerative stage" (S211) and proceeds to the processing of S204.

[Effects of the brake control device 1 of the present disclosure]
According to the brake control device 1 of the present disclosure, when the regenerative brake does not work sufficiently due to a small electric capacity that can be charged to the battery 5, the brake control unit 125 compensates for the insufficient regenerative braking force of the regenerative brake with respect to the required braking force Pw by using brakes other than the regenerative brake. Therefore, the brake control unit 125 can prevent the host vehicle 100 from getting too close to the vehicle ahead, thereby preventing the driver from feeling fear.

Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination also has the effect of the original embodiment.

REFERENCE SIGNS LIST 1 Brake control device 2 Vehicle speed sensor 3 Distance sensor 4 Voltage sensor 5 Battery 6 Motor 7 Friction brake 11 Memory unit 12 Control unit 100 Vehicle 121 Acquisition unit 122 Identification unit 123 Selection unit 124 Regeneration control unit 125 Brake control unit 200 Front vehicle

Claims (13)

A braking control device that controls regenerative braking based on a distance between a vehicle and a preceding vehicle,
A storage unit that stores a plurality of pieces of identification information corresponding to the magnitude of a generated regenerative braking force;
an acquisition unit that acquires a remaining battery charge of a battery mounted on the host vehicle , the battery being capable of being charged with electric power generated by the regenerative brake when the regenerative brake performs a regenerative operation;
a determination unit that determines a necessary braking force required for decelerating the host vehicle based on the distance;
a selection unit that specifies a possible regenerative force for specifying the regenerative braking force that can be output based on the acquired battery remaining amount, and selects one of the one or more pieces of identification information that correspond to the regenerative braking force that can be output by the regenerative brake in the state of the battery remaining amount, the one or more pieces of identification information being specified from the plurality of pieces of identification information stored in the storage unit, the one or more pieces of identification information being smaller than a maximum value of the regenerative braking force corresponding to the specified possible regenerative force ;
a braking control unit that compensates for a braking force that is insufficient for the required braking force, when the regenerative braking force corresponding to the identification information selected by the selection unit is insufficient for the required braking force, by a brake other than the regenerative brake;
A braking control device comprising: A braking control device that controls regenerative braking based on a distance between a vehicle and a preceding vehicle,
A storage unit that stores a plurality of pieces of identification information corresponding to the magnitude of a generated regenerative braking force;
an acquisition unit that acquires a remaining battery charge of a battery mounted on the vehicle , the battery being capable of being charged with electric power generated by the regenerative brake when the regenerative brake performs a regenerative operation;
a determination unit that determines a necessary braking force required for decelerating the host vehicle based on the distance;
a selection unit that selects one of the identification information items from one or more identification information items corresponding to a regenerative braking force that can be output by the regenerative brake in a state of the battery remaining amount, the identification information items being identified from the plurality of identification information items stored in the storage unit based on the acquired battery remaining amount;
a braking control unit that compensates for a braking force that is insufficient for the required braking force, when the regenerative braking force corresponding to the identification information selected by the selection unit is insufficient for the required braking force, by a brake other than the regenerative brake;
Equipped with
the selection unit identifies a possible regenerative force for identifying the regenerative braking force that can be output based on the remaining battery charge, identifies first identification information on condition that the identified possible regenerative force is less than a first threshold value, and identifies second identification information corresponding to the regenerative braking force that is greater than the regenerative braking force corresponding to the first identification information on condition that the possible regenerative force is equal to or greater than the first threshold value.
Brake control device. A braking control device that controls regenerative braking based on a distance between a vehicle and a preceding vehicle,
A storage unit that stores a plurality of pieces of identification information corresponding to the magnitude of a generated regenerative braking force;
an acquisition unit that acquires a remaining battery charge of a battery mounted on the vehicle , the battery being capable of being charged with electric power generated by the regenerative brake when the regenerative brake performs a regenerative operation;
a determination unit that determines a necessary braking force required for decelerating the host vehicle based on the distance;
a selection unit that selects, based on the required braking force, from one or more pieces of identification information corresponding to regenerative braking forces that can be output by the regenerative brake in a state of the battery remaining amount, the identification information corresponding to a minimum regenerative braking force that makes the regenerative braking force corresponding to the selected identification information equal to or greater than the required braking force, the identification information being specified from the plurality of pieces of identification information stored in the storage unit based on the acquired battery remaining amount ;
a braking control unit that compensates for a braking force that is insufficient for the required braking force, when the regenerative braking force corresponding to the identification information selected by the selection unit is insufficient for the required braking force, by a brake other than the regenerative brake;
A braking control device comprising: A braking control device that controls regenerative braking based on a distance between a vehicle and a preceding vehicle,
A storage unit that stores a plurality of pieces of identification information corresponding to the magnitude of a generated regenerative braking force;
an acquisition unit that acquires a remaining battery charge of a battery mounted on the vehicle , the battery being capable of being charged with electric power generated by the regenerative brake when the regenerative brake performs a regenerative operation;
a determination unit that determines a necessary braking force required for decelerating the host vehicle based on the distance;
a selection unit that selects, based on the required braking force, one of the identification information from one or more identification information corresponding to regenerative braking forces that can be output by the regenerative brake in a state of the battery remaining amount, which are identified from the plurality of identification information stored in the storage unit based on the acquired battery remaining amount , and selects the identification information corresponding to a maximum regenerative braking force when the regenerative braking forces corresponding to all of the identified identification information are less than the required braking force;
a braking control unit that compensates for a braking force that is insufficient for the required braking force, when the regenerative braking force corresponding to the identification information selected by the selection unit is insufficient for the required braking force, by a brake other than the regenerative brake;
A braking control device comprising: A braking control device that controls regenerative braking based on a distance between a vehicle and a preceding vehicle,
A storage unit that stores a plurality of pieces of identification information corresponding to the magnitude of a generated regenerative braking force;
an acquisition unit that acquires a remaining battery charge of a battery mounted on the host vehicle , the battery being capable of being charged with electric power generated by the regenerative brake when the regenerative brake performs a regenerative operation;
a determination unit that determines a necessary braking force required for decelerating the host vehicle based on the distance;
a selection unit that selects, based on the required braking force, one of the identification information items that corresponds to a regenerative braking force that can be output by the regenerative brake in a state of the battery remaining amount, the identification information item being identified from the plurality of identification information items stored in the storage unit based on the acquired battery remaining amount ;
a braking control unit that compensates for a braking force that is insufficient for the required braking force, when the regenerative braking force corresponding to the identification information selected by the selection unit is insufficient for the required braking force, by a brake other than the regenerative brake;
Equipped with
the selection unit selects first identification information from the one or more identification information when the required braking force changes from less than a first reference value to equal to or greater than the first reference value, and does not select the first identification information from the one or more identification information when the required braking force becomes less than a second reference value that is smaller than the first reference value after selecting the first identification information.
Brake control device. a regenerative control unit that generates the regenerative braking force corresponding to the identification information selected by the selection unit, and when a maximum value of the regenerative braking force corresponding to the possible regenerative force is less than a minimum regenerative braking force among the regenerative braking forces corresponding to the multiple identification information stored in the memory unit, generates a maximum regenerative braking force that can be generated at a time point when the maximum value of the regenerative braking force corresponding to the possible regenerative force is less than a minimum regenerative braking force among the regenerative braking forces corresponding to the multiple identification information stored in the memory unit.
3. The braking control device according to claim 2 . a regenerative control unit that, when the selection unit selects first identification information, regeneratively charges the battery so that a charging current for charging the battery has a first current value, and, when the selection unit selects second identification information corresponding to the regenerative braking force that is larger than the regenerative braking force corresponding to the first identification information, regeneratively charges the battery so that the charging current has a second current value that is larger than the first current value.
A braking control device according to any one of claims 1 to 5 . the selection unit selects one of the one or more pieces of identification information corresponding to the regenerative braking force that changes depending on a rotation speed of a motor mounted on the vehicle.
A braking control device according to any one of claims 1 to 5 . A braking control method for controlling regenerative braking based on a distance between a host vehicle and a preceding vehicle, comprising:
acquiring a remaining battery charge of a battery mounted on the host vehicle , the battery being capable of being charged with electric power generated by the regenerative brake when the regenerative brake performs a regenerative operation ;
determining a necessary braking force required to decelerate the host vehicle based on the distance;
A step of referring to a memory unit that stores multiple pieces of identification information corresponding to the magnitude of the regenerative braking force to be generated, identifying a possible regenerative force for identifying the regenerative braking force that can be output based on the acquired remaining battery charge, and selecting one of the one or more pieces of identification information corresponding to the regenerative braking force that can be output by the regenerative brake in the state of the remaining battery charge identified from the multiple pieces of identification information stored in the memory unit, the one or more pieces of identification information being smaller than a maximum value of the regenerative braking force corresponding to the identified possible regenerative force;
a step of compensating for a braking force that is insufficient for the required braking force, the regenerative braking force corresponding to the selected identification information, by a brake other than the regenerative brake;
The braking control method comprises: A braking control method for controlling regenerative braking based on a distance between a host vehicle and a preceding vehicle, comprising:
acquiring a remaining battery charge of a battery mounted on the host vehicle , the battery being capable of being charged with electric power generated from the regenerative brake when the regenerative brake performs a regenerative operation ;
determining a necessary braking force required to decelerate the host vehicle based on the distance;
A step of referring to a storage unit storing a plurality of pieces of identification information corresponding to the magnitude of a regenerative braking force to be generated, and selecting one of the pieces of identification information corresponding to a regenerative braking force that can be output by the regenerative brake in a state of the battery remaining amount, the identification information being specified from the plurality of pieces of identification information stored in the storage unit based on the acquired battery remaining amount;
a step of compensating for a braking force that is insufficient for the required braking force, the regenerative braking force corresponding to the selected identification information, by a brake other than the regenerative brake;
having
In the step of selecting one of the identification information, a possible regenerative force for identifying the regenerative braking force that can be output based on the remaining battery charge is identified, and a first identification information is identified on the condition that the identified possible regenerative force is less than a first threshold value, and a second identification information corresponding to the regenerative braking force that is greater than the regenerative braking force corresponding to the first identification information is identified on the condition that the possible regenerative force is equal to or greater than the first threshold value.
Braking control method. The computer executes
A braking control method for controlling regenerative braking based on a distance between a host vehicle and a preceding vehicle, comprising:
acquiring a remaining battery charge of a battery mounted on the host vehicle , the battery being capable of being charged with electric power generated from the regenerative brake when the regenerative brake performs a regenerative operation ;
determining a necessary braking force required to decelerate the host vehicle based on the distance;
A step of referring to a storage unit that stores a plurality of pieces of identification information corresponding to the magnitude of the regenerative braking force to be generated, and selecting, based on the required braking force, from a plurality of pieces of identification information corresponding to the regenerative braking forces that can be output by the regenerative brake in the state of the battery remaining charge, which are identified from the plurality of identification information stored in the storage unit based on the acquired battery remaining charge, the identification information corresponding to a minimum regenerative braking force such that the regenerative braking force corresponding to the selected identification information is equal to or greater than the required braking force ;
a step of compensating for a braking force that is insufficient for the required braking force, the regenerative braking force corresponding to the selected identification information, by a brake other than the regenerative brake;
The braking control method comprises: A braking control method for controlling regenerative braking based on a distance between a host vehicle and a preceding vehicle, comprising:
acquiring a remaining battery charge of a battery mounted on the host vehicle , the battery being capable of being charged with electric power generated by the regenerative brake when the regenerative brake performs a regenerative operation ;
determining a necessary braking force required to decelerate the host vehicle based on the distance;
a step of referring to a memory unit that stores multiple pieces of identification information corresponding to the magnitude of the regenerative braking force to be generated, selecting, based on the required braking force, one of the identification information from one or more pieces of identification information corresponding to the regenerative braking force that can be output by the regenerative brake in the state of the battery remaining charge, which are identified from the multiple pieces of identification information stored in the memory unit based on the acquired battery remaining charge , and selecting, based on the required braking force, the identification information corresponding to the maximum regenerative braking force when the regenerative braking forces corresponding to all of the identified identification information are less than the required braking force ;
a step of compensating for a braking force that is insufficient for the required braking force, the regenerative braking force corresponding to the selected identification information, by a brake other than the regenerative brake;
A braking control method comprising: A braking control method for controlling regenerative braking based on a distance between a host vehicle and a preceding vehicle, comprising:
acquiring a remaining battery charge of a battery mounted on the host vehicle , the battery being capable of being charged with electric power generated by the regenerative brake when the regenerative brake performs a regenerative operation ;
determining a necessary braking force required to decelerate the host vehicle based on the distance;
a step of referring to a storage unit storing a plurality of pieces of identification information corresponding to the magnitude of a regenerative braking force to be generated, and selecting, based on the required braking force, one of the pieces of identification information from one or more pieces of identification information corresponding to a regenerative braking force that can be output by the regenerative brake in a state of the battery remaining amount, the identification information being specified from the plurality of pieces of identification information stored in the storage unit based on the acquired battery remaining amount;
a step of compensating for a braking force that is insufficient for the required braking force, the regenerative braking force corresponding to the selected identification information, by a brake other than the regenerative brake;
having
In the step of selecting any one of the identification information, when the required braking force changes from less than a first reference value to equal to or greater than the first reference value, a first identification information is selected from the one or more identification information, and when the required braking force becomes less than a second reference value that is smaller than the first reference value after the selection of the first identification information, the first identification information is not selected from the one or more identification information.
Braking control method.

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