Vehicle control system

Abstract

To provide a vehicle control device which sets reduction speed when reducing regenerative brake force to be gentle.SOLUTION: A vehicle control device 10 is applied to a vehicle having a regenerative brake device. The vehicle control device 10 brakes a vehicle on the basis of a target value of deceleration of the vehicle according to a brake request for braking the vehicle. The vehicle control device 10 includes a brake determination part 11 for determining that the vehicle is being braked on the basis of the brake request. The vehicle control device 10 includes a target deceleration calculation part 12 for calculating first target deceleration as a target value of deceleration of the vehicle, on the basis of the brake request, when the vehicle is being braked. The vehicle control device 10 includes an adjustment processing part 13 for executing deceleration adjustment processing of calculating second target deceleration obtained by adjusting the first target deceleration so that the magnitude of a change rate is reduced when the first target deceleration is brought close to "0".SELECTED DRAWING: Figure 2

Description

Technical Field

[0004]

[0001] The present invention relates to a vehicle control device.

Background Art

[0002] Patent Document 1 discloses a braking control device for a vehicle that cooperatively controls a hydraulic braking device and a regenerative braking device. This braking control device is configured to increase the opportunity of using the regenerative braking device to improve the regeneration efficiency.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The regenerative braking force is generated by operating the generator. The regenerative braking force generated along with the power generation by the generator has higher responsiveness compared to the hydraulic braking force. Therefore, when trying to reduce the regenerative braking force while the regenerative braking force is being generated, the reduction speed of the regenerative braking force may increase due to the high responsiveness. If the reduction of the regenerative braking force becomes steep and the regenerative braking force suddenly stops acting, there is a risk that the longitudinal acceleration of the vehicle repeatedly fluctuates in the acceleration direction and the deceleration direction. That is, there is a risk that the vehicle vibrates. As disclosed in Patent Document 1, there is a problem that the situation where vibration may occur becomes more likely as the opportunity to generate the regenerative braking force is increased in an attempt to improve the regeneration efficiency.

Means for Solving the Problems

[0005] The vehicle control device for solving the above problems is applied to a vehicle having a regenerative braking device that generates regenerative braking force as a braking force for braking the vehicle, and brakes the vehicle based on a target value of the vehicle's deceleration in response to a braking request for braking the vehicle, and comprises: a braking determination unit that determines that the vehicle is being braked based on the braking request; a target deceleration calculation unit that calculates a first target deceleration as a target value of the vehicle's deceleration in response to the braking request when the vehicle is being braked; and an adjustment processing unit that performs a deceleration adjustment process to calculate a second target deceleration by adjusting the first target deceleration so as to reduce the magnitude of the rate of change when the first target deceleration approaches "0", and brakes the vehicle based on the second target deceleration.

[0006] According to the above configuration, the magnitude of the rate of change in the target deceleration when the first target deceleration approaches "0" is reduced, thereby suppressing abrupt fluctuations in the target deceleration. For this reason, in vehicles equipped with a regenerative braking system, when the first target deceleration approaches "0", that is, when reducing the braking force, the rate of decrease of the generated regenerative braking force tends to be gradual. This suppresses the sudden cessation of the regenerative braking force. This suppresses vibrations that may occur when the regenerative braking force suddenly ceases to function. Note that the magnitude of the rate of change in the target deceleration mentioned above refers to the absolute value of the rate of change. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a block diagram showing the vehicle control system and the vehicle. [Figure 2] Figure 2 is a block diagram showing the vehicle control device. [Figure 3] Figure 3 is a flowchart showing the processing flow performed by the vehicle control system. [Figure 4] Figure 4 shows the relationship between the target deceleration and the rate of change of the target deceleration used in the deceleration adjustment process performed by the vehicle control device. [Figure 5]Figure 5 is a flowchart showing the processing flow performed by the vehicle control system. [Figure 6] Figure 6 is a timing chart showing the transition between braking determination and target deceleration when deceleration adjustment processing is performed. [Figure 7] Figure 7 is a block diagram showing an example of a modified vehicle control system. [Figure 8] Figure 8 is a block diagram showing the vehicle control device in the modified example. [Modes for carrying out the invention]

[0008] An embodiment of the vehicle control device will be described below with reference to Figures 1 to 6. Figure 1 shows the vehicle control device 10 and the vehicle 90 to which the vehicle control device 10 is applied. <Vehicle> An example of vehicle 90 is a hybrid electric vehicle. For example, vehicle 90 includes a motor generator 71 and an internal combustion engine 72, as shown in Figure 1. Vehicle 90 includes a hybrid system 70 composed of the motor generator 71 and the internal combustion engine 72. The hybrid system 70 can generate driving force for vehicle 90. That is, vehicle 90 can transmit driving force to the wheels using the motor generator 71, which functions as an electric motor, and the internal combustion engine 72 as power sources. The hybrid system 70 may include a hybrid control device that controls the motor generator 71 and the internal combustion engine 72.

[0009] Vehicle 90 is equipped with a regenerative braking system. One example of a regenerative braking system is a motor-generator 71. By making the motor-generator 71 function as a generator, regenerative braking force can be applied to the wheels. As another example, the regenerative braking system may be an in-wheel motor.

[0010] Vehicle 90 may be equipped with a friction brake system 80. The friction brake system 80 can apply a frictional braking force to the wheels. An example of a friction brake system is a hydraulic brake system. A hydraulic brake system is equipped with a braking mechanism corresponding to each wheel. The braking mechanism consists of a rotating body that rotates integrally with the wheel, a friction material that can be pressed against the rotating body, and a wheel cylinder that presses the friction material against the rotating body according to hydraulic pressure. An example of a braking mechanism is a disc brake. The braking mechanism may also be a drum brake. Another example of a friction brake system is an electric brake system that mechanically transmits the driving force of an electric motor to press the friction material against the rotating body.

[0011] Vehicle 90 is equipped with a braking operation member 91. The braking operation member 91 can be operated by the driver of vehicle 90. The braking operation member 91 is, for example, a brake pedal. Vehicle 90 can generate a braking force corresponding to the amount of operation of the braking operation member 91. The amount of operation of the braking operation member 91 corresponds to a braking request of vehicle 90. The braking request is a value corresponding to the braking force to be applied to vehicle 90.

[0012] Vehicle 90 is equipped with an in-vehicle network. Vehicle 90 is equipped with multiple processing circuits connected to the in-vehicle network. Vehicle control device 10 is an example of a processing circuit. Each processing circuit connected to the in-vehicle network can communicate with each other via the in-vehicle network.

[0013] Vehicle 90 is equipped with various sensors. Detection signals from these sensors are input to the in-vehicle network. Figure 1 shows brake sensor SE1 as an example of the various sensors.

[0014] The brake sensor SE1 can detect the operation of the braking operating member 91. For example, the brake sensor SE1 can detect the amount Bp of operation of the braking operating member 91. The brake sensor SE1 may also be capable of detecting whether or not the braking operating member 91 is being operated.

[0015] The vehicle 90 may include an assistance control device 60. The assistance control device 60 includes a processing circuit that assists the running of the vehicle 90. Examples of the control executed by the assistance control device 60 include automatic driving, automatic parking, adaptive cruise control, and collision avoidance braking. The vehicle control device 10 can automatically brake the vehicle 90 by controlling the vehicle 90 based on a braking request input from the assistance control device 60.

[0016] <Vehicle control device> The vehicle control device 10 is constituted by a processing circuit that targets the vehicle 90 for control. For example, as shown in FIG. 1, the vehicle control device 10 includes a CPU 10a as a processing device. For example, the vehicle control device 10 includes a ROM 10b as a memory. Various programs for the CPU 10a to execute various controls are stored in the ROM 10b of the vehicle control device 10.

[0017] The vehicle control device 10 is constituted by a plurality of functional units that execute various controls. FIG. 2 shows, as an example of functional units, a braking determination unit 11, a target deceleration calculation unit 12, an adjustment processing unit 13, a regeneration cooperation unit 14, and a control unit 19. Each functional unit included in the vehicle control device 10 can transmit and receive information to and from each other.

[0018] The braking determination unit 11 can determine whether the vehicle is in the process of braking based on a braking request. An example of a braking request is an operation amount Bp calculated based on a detection signal from a brake sensor SE1. When the operation amount Bp is greater than "0", it indicates that there is a braking request. When the operation amount Bp is "0", it indicates that there is no braking request. A decrease in the operation amount Bp from a situation where the operation amount Bp is greater than "0" to "0" is referred to as the cancellation of the braking request.

[0019] The braking determination unit 11 determines that braking is in progress when a braking request is received. When the braking determination unit 11 determines that the vehicle 90 is braking, it turns on, for example, braking determination F1. When braking determination F1 is ON, it means that a signal indicating that the vehicle 90 is braking is being output. When there is no braking request, the braking determination unit 11 determines that braking is not in progress. When the braking determination unit 11 determines that the vehicle 90 is not braking, it turns off braking determination F1.

[0020] The target deceleration calculation unit 12 can calculate a first target deceleration DVT1 as a target value for the deceleration degree of the vehicle 90. Deceleration indicates the rate of change of the vehicle 90's speed. The vehicle control device 10 can brake the vehicle 90 by applying braking force to the vehicle 90 according to the target value of the deceleration degree. In this embodiment, deceleration takes a positive value when the vehicle 90 is decelerating. Deceleration takes a larger value the greater the change in the vehicle 90's speed in the deceleration direction.

[0021] The target deceleration calculation unit 12 calculates a first target deceleration DVT1 based on the manipulated amount Bp when the vehicle 90 is braking. The target deceleration calculation unit 12 calculates a larger first target deceleration DVT1 the larger the manipulated amount Bp is.

[0022] The adjustment processing unit 13 performs deceleration adjustment processing. Deceleration adjustment processing is the process of adjusting the rate of change of the target value of the degree of deceleration. More specifically, it is the process of reducing the magnitude of the rate of change when the target deceleration approaches "0". As will be described in detail later, in the deceleration adjustment processing, the adjustment processing unit 13 calculates the second target deceleration DVT2 based on the first target deceleration DVT1. In this specification, the magnitude of the rate of change of the target deceleration refers to the absolute value of the rate of change. Similarly, the magnitude of the target deceleration refers to the absolute value of the target degree of deceleration.

[0023] The second target deceleration DVT2 is a value obtained by adjusting the first target deceleration DVT1 so that the magnitude of the rate of change when the first target deceleration DVT1 approaches "0" is reduced. The magnitude of the rate of change of the second target deceleration DVT2 is adjusted to be smaller than the magnitude of the rate of change of the first target deceleration DVT1.

[0024] When the first target deceleration DVT1 approaches "0", it corresponds to a decrease in the manipulated variable Bp, i.e., a decrease in the braking request. Here, since deceleration takes a positive value when the vehicle 90 is decelerating, when the first target deceleration DVT1 approaches "0", it can be rephrased as the first target deceleration DVT1 becoming smaller. The rate of change of deceleration is the time derivative of deceleration. When deceleration decreases over time, the rate of change of deceleration takes a negative value.

[0025] The adjustment processing unit 13 may perform a delay process. The delay process, if it is in the process of performing a deceleration adjustment process, is a process that continues braking the vehicle 90 based on the second target deceleration DVT2 even if the braking request is resolved.

[0026] The regenerative braking coordination unit 14 has a function to perform coordinated control of friction braking force and regenerative braking force. The regenerative braking coordination unit 14 is an example of a regenerative control unit that controls regenerative braking force. The regenerative braking coordination unit 14 calculates the required regenerative braking force BRT as the required value of regenerative braking force based on the regeneration ratio.

[0027] The regenerative braking ratio is explained below. The regenerative braking ratio is a value that indicates the proportion of regenerative braking force to the total braking force applied to the vehicle 90. For example, the regenerative braking ratio is a value between "0" and "1". In the following, the total braking force applied to the vehicle 90 to control its deceleration toward a target value may also be referred to as the target braking force. The total braking force applied to the vehicle 90 may also be referred to as the total braking force.

[0028] When the regeneration ratio is "0", the friction braking system 80 is operated so that the target braking force is met by friction braking force alone. When the regeneration ratio is "1", the regenerative braking system is operated so that the target braking force is met by regenerative braking force alone. When the regeneration ratio is greater than "0" and less than "1", the friction braking system 80 and the regenerative braking system are operated so that the sum of friction braking force and regenerative braking force equals the target braking force. In this case, the greater the regeneration ratio is greater than "0", the larger the proportion of regenerative braking force becomes.

[0029] The regenerative braking ratio can be set based on, for example, a target value for the degree of deceleration. For example, if the target value for the degree of deceleration is large, i.e., if the target braking force is large, it is preferable to increase the proportion of frictional braking force. In other words, if the target value for the degree of deceleration is large, it is preferable to decrease the regenerative braking ratio. The regenerative braking ratio can also be set based on vehicle speed, etc.

[0030] The regenerative braking unit 14 calculates the required regenerative braking force BRT based on the regeneration ratio and the second target deceleration DVT2. The regenerative braking unit 14 calculates the required friction braking force BPT as the required value of the friction braking force so that the sum of the regenerative braking force and the friction braking force equals the target braking force. The required regenerative braking force BRT is transmitted to the regenerative braking device. The regenerative braking device generates regenerative braking force corresponding to the required regenerative braking force BRT. For example, the required regenerative braking force BRT is transmitted to the hybrid system 70.

[0031] The control unit 19 outputs a signal to control the friction braking device 80 based on the required friction braking force BPT. The control unit 19 operates the friction braking device 80 to generate a friction braking force corresponding to the required friction braking force BPT.

[0032] <Deceleration adjustment process> Figure 3 shows the processing flow when the adjustment processing unit 13 performs deceleration adjustment processing. This processing routine is repeatedly executed at predetermined intervals while the vehicle 90 is braking.

[0033] When this processing routine is started, in step S101, the adjustment processing unit 13 first determines whether the start condition is met. If the start condition is not met (S101: NO), the adjustment processing unit 13 terminates this processing routine. On the other hand, if the start condition is met (S101: YES), the adjustment processing unit 13 proceeds to step S102.

[0034] Let's explain an example of a starting condition. For example, the adjustment processing unit 13 can determine that the starting condition is met if condition (A) is met. For example, condition (A) may be that the manipulated variable Bp is decreasing. Condition (A) can also be that the first target deceleration DVT1 is fluctuating so as to approach "0".

[0035] The adjustment processing unit 13 may determine that the start condition is met if, in addition to condition (A) being met, condition (B) is also met. In other words, the adjustment processing unit 13 may determine that the start condition is not met if condition (B) is not met, even if condition (A) is met.

[0036] For example, condition (B) includes at least one of the following examples. One example of condition (B) is that the vehicle speed is greater than the judgment speed. The judgment speed can be a value calculated in advance through experiments or the like. The judgment speed is, for example, the minimum vehicle speed at which the regenerative braking system of vehicle 90 can generate regenerative braking force. Another example of condition (B) is that the regeneration ratio is not "0". Another example of condition (B) is that the rate of decrease of the manipulated amount Bp is equal to or greater than the judgment speed. The judgment speed can be set as a threshold for determining whether or not the operation of the braking operating member 91 is being performed suddenly.

[0037] In this specification, the expression "at least one" means "one or more" of the desired options. For example, if there are two options, "at least one" means either "only one option" or "both of the two options." As another example, if there are three or more options, "at least one" means either "only one option" or "any combination of two or more options."

[0038] In step S102, the adjustment processing unit 13 starts the deceleration adjustment process. An example of the deceleration adjustment process will be explained using Figure 4. Figure 4 shows the relationship between the first target deceleration DVT1 and the rate of change J. The adjustment processing unit 13 includes a calculation map that shows this relationship. The calculation map is stored, for example, in the ROM 10b of the vehicle control device 10. The adjustment processing unit 13 calculates the rate of change J based on the relationship shown in Figure 4. While the deceleration adjustment process is being executed, the adjustment processing unit 13 calculates the second target deceleration DVT2 so that its rate of change becomes the rate of change J.

[0039] Figure 4 shows the rate of change guard value as a solid line. The rate of change guard value satisfies the relationship that the larger the first target deceleration DVT1, the larger the difference between the rate of change J corresponding to the first target deceleration DVT1 and "0". In other words, the larger the first target deceleration DVT1, the smaller the rate of change J corresponding to the first target deceleration DVT1. As shown in Figure 4, in the rate of change guard value, the rate of change J corresponding to the case where the first target deceleration DVT1 is "0" is set to be smaller than "0".

[0040] In the calculation map, the usable region is defined as the area where the rate of change J is greater than or equal to the rate of change guard value. The magnitude of the rate of change guard value corresponds to the "upper limit" of the rate of change. The magnitude of the rate of change guard value increases as the magnitude of the first target deceleration DVT1 increases. In other words, the absolute value of the rate of change guard value increases as the absolute value of the first target deceleration DVT1 increases. In the relationship shown in Figure 4, the usable region is the area from "0" to the upper limit value. The rate of change guard value can be a value calculated through experiments, etc. The usable region is set as a set of points where the delay in the reduction of braking force can be reduced while suppressing vibration of the vehicle 90.

[0041] In the deceleration adjustment process, if the rate of change of the first target deceleration DVT1 falls within the usable range, the adjustment processing unit 13 sets the rate of change J to the same value as the rate of change of the first target deceleration DVT1. On the other hand, if the rate of change of the first target deceleration DVT1 is smaller than the rate of change guard value, the adjustment processing unit 13 sets the rate of change J to the same value as the rate of change guard value. In other words, if the magnitude of the rate of change of the first target deceleration DVT1 is greater than the upper limit, the adjustment processing unit 13 sets the rate of change J to the same value as the rate of change guard value.

[0042] According to the deceleration adjustment process, the second target deceleration DVT2 is calculated as the same value as the first target deceleration DVT1 if the rate of change of the first target deceleration DVT1 is greater than or equal to the rate of change guard value. If the rate of change of the first target deceleration DVT1 is less than the rate of change guard value, the second target deceleration DVT2 is calculated as a value adjusted so that the magnitude of the rate of change is smaller compared to the rate of change of the first target deceleration DVT1. Specifically, the adjusted second target deceleration DVT2 will be a larger value than the first target deceleration DVT1. In other words, the magnitude of the braking force corresponding to the second target deceleration DVT2 will be greater than the magnitude of the braking force corresponding to the first target deceleration DVT1.

[0043] When the deceleration adjustment process is started in step S102, the adjustment processing unit 13 proceeds to step S103. In step S103, the adjustment processing unit 13 starts delay processing. During delay processing, the adjustment processing unit 13 instructs the braking determination unit 11 to continue turning on the braking determination F1. Therefore, the braking determination F1 remains ON while the delay processing is being executed. When delay processing starts in step S103, the adjustment processing unit 13 terminates this processing routine.

[0044] In other words, the consequences of initiating the delay process are as follows: While the delay process is running, the braking judgment F1 is not turned OFF. While the delay process is running, the braking judgment F1 is not turned OFF even if the braking request is canceled. While the delay process is running, the braking judgment F1 is not turned OFF even if the manipulated variable Bp becomes "0". While the delay process is running, the braking judgment F1 is not turned OFF even if the first target deceleration DVT1 becomes "0". While the deceleration adjustment process is running, the braking judgment F1 is not turned OFF.

[0045] Figure 5 shows the processing flow executed by the adjustment processing unit 13. This processing routine is repeatedly executed at predetermined intervals during the execution of the deceleration adjustment process. It can also be said that this processing routine is repeatedly executed at predetermined intervals during the execution of the delay process.

[0046] When this processing routine is started, in step S201, the adjustment processing unit 13 first determines whether the termination condition is met. If the termination condition is not met (S201: NO), the adjustment processing unit 13 terminates this processing routine. On the other hand, if the termination condition is met (S201: YES), the adjustment processing unit 13 proceeds to step S202.

[0047] An example of a termination condition is explained below. For example, if at least one of the conditions exemplified below is met, it can be determined that the termination condition has been met. Examples of conditions included in the termination condition are (Termination Condition 1) to (Termination Condition 5). (Termination Condition 1) The second target deceleration DVT2 became "0". (Termination Condition 2) A specified time has elapsed since the braking request was released. (Termination Condition 3) Vehicle 90 has come to a stop. (Termination Condition 4) A request to accelerate vehicle 90 has been generated. (Termination Condition 5) An abnormality has occurred in the braking system.

[0048] Regarding (termination condition 2), the specified time is a threshold for setting the maximum time that the braking judgment F1 remains ON even after the braking request has been resolved. In other words, the specified time is a threshold for setting the maximum time that will be delayed in turning off the braking judgment F1. The specified time can be a value calculated in advance through experiments or other means.

[0049] Regarding (termination condition 3), vehicle 90 is considered stopped when its speed has decelerated to "0". Alternatively, vehicle 90 may be considered stopped when its speed has decelerated to a speed slightly greater than "0".

[0050] Regarding (termination condition 4), for example, it can be said that a request to accelerate the vehicle 90 has been generated when the accelerator pedal is started to be operated. The accelerator pedal is an example of an acceleration control member provided by the vehicle 90. The acceleration control member can be operated by the driver of the vehicle 90. The vehicle 90 transmits driving force to the wheels based on the amount of operation of the acceleration control member.

[0051] With respect to (termination condition 5), the braking system shall be at least one of a regenerative braking system and a friction braking system 80. In step S202, the adjustment processing unit 13 completes the deceleration adjustment process. After that, the adjustment processing unit 13 proceeds to step S203.

[0052] In step S203, the adjustment processing unit 13 terminates the delay processing. After that, the adjustment processing unit 13 terminates this processing routine. <Mechanism of Action and Effects> The operation and effects of this embodiment will now be described.

[0053] Figure 6 shows the change in the target deceleration level when the vehicle control device 10 performs deceleration adjustment processing. In the example shown in Figure 6, as shown in Figure 6(a), the manipulated variable Bp increases from timing t11. The manipulated variable Bp remains constant from timing t12 to timing t13. The manipulated variable Bp decreases from timing t13 onward. The manipulated variable Bp decreases to "0" at timing t15.

[0054] In the example shown in Figure 6, the start condition is determined to be met at timing t13 when the manipulated variable Bp begins to decrease (S101: YES). Therefore, the deceleration adjustment process and delay process are started from timing t13 (S102 and S103).

[0055] Figure 6(c) shows the progression of the first target deceleration DVT1 with a dashed line, and the progression of the second target deceleration DVT2 with a solid line. As shown by the dashed line in Figure 6(c), the first target deceleration DVT1 increases from timing t11. The first target deceleration DVT1 remains constant from timing t12 to timing t13. The first target deceleration DVT1 decreases from timing t13 onward. The first target deceleration DVT1 decreases to "0" at timing t15.

[0056] The second target deceleration DVT2, calculated by the deceleration adjustment process, is calculated to be the same value as the first target deceleration DVT1 during the period from timing t13 to timing t14, as shown by the solid line in Figure 6(c). From timing t14 onward, the magnitude of the rate of change of the second target deceleration DVT2 is made smaller compared to the magnitude of the rate of change of the first target deceleration DVT1. Therefore, the second target deceleration DVT2 is calculated to be a larger value compared to the first target deceleration DVT1. As a result, from timing t14 onward, the rate of decrease of the regenerative braking force becomes more gradual. As shown by the solid line in Figure 6(c), the second target deceleration DVT2 decreases to "0" at timing t16, which is after timing t15.

[0057] According to the vehicle control device 10, a second target deceleration DVT2 is calculated, which is adjusted to have a smaller rate of change when the first target deceleration DVT1 approaches "0". This suppresses abrupt fluctuations in the target deceleration. Therefore, when the first target deceleration DVT1 approaches "0" in a vehicle 90 equipped with a regenerative braking system, that is, when reducing the braking force, the rate of decrease of the generated regenerative braking force tends to be gradual. This suppresses the sudden cessation of the regenerative braking force. This suppresses vibrations that may occur when the regenerative braking force suddenly ceases to act. According to the vehicle control device 10, for example, even when the speed at which the brake pedal is released is fast, the rate of decrease of the regenerative braking force can be made gradual. This suppresses vibrations that may occur in the vehicle 90 when the regenerative braking force acting on the vehicle 90 is reduced.

[0058] Furthermore, in the vehicle control device 10, the rate of change J is not easily reduced when the first target deceleration DVT1 is large. Therefore, when the first target deceleration DVT1 is large, the rate of decrease of the regenerative braking force is not easily slowed down. This reduces the delay in the decrease of braking force when the first target deceleration DVT1 is large. According to the vehicle control device 10, while reducing the delay in the decrease of braking force, the rate of decrease of the regenerative braking force can be slowed down if there is a risk of vibration occurring due to the decrease in regenerative braking force.

[0059] Figure 6(b) shows the transition of the braking judgment F1 with a solid line. The braking judgment F1 is turned ON from timing t11 when the manipulated variable Bp begins to increase. As mentioned above, the manipulated variable Bp is "0" at timing t15, but due to the delay processing, the braking judgment F1 is not turned OFF at timing t15. The braking judgment F1, which remains ON after timing t15, is turned OFF when the termination condition is met. Specifically, the braking judgment F1 is turned OFF at timing t16 when the second target deceleration DVT2 becomes "0".

[0060] Figure 6(b) shows the transition of the braking judgment F1 in the case where no delay processing is performed, as a comparative example, indicated by a dashed line. In the comparative example, as shown by the dashed line in Figure 6(b), the braking judgment F1 is turned OFF at timing t15 when the manipulated variable Bp becomes "0".

[0061] As shown in Figure 6(b), during the delay process, the determination that braking has ended is delayed compared to the comparative example. According to the vehicle control device 10, the delay process allows the braking determination F1 to remain ON. According to the vehicle control device 10, the delay process allows the calculation of the second target deceleration DVT2, which is the target value of the deceleration degree, to continue. According to the vehicle control device 10, the delay process allows the braking of the vehicle 90 based on the second target deceleration DVT2 to continue even after the braking request has been resolved.

[0062] (Example of change) This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0063] In the above embodiment, an example was shown in which the target deceleration was adjusted using a calculation map as illustrated in Figure 4 as part of the deceleration adjustment process. The configuration for calculating the target deceleration with an adjusted rate of change is not limited to this. For example, the second target deceleration DVT2 can also be calculated using the first target deceleration DVT1 and a correction value K. The correction value K is set as a value that corrects the first target deceleration DVT1 such that the larger the magnitude of the first target deceleration DVT1, the smaller the deviation of the second target deceleration DVT2 from the first target deceleration DVT1 becomes.

[0064] As an example, the second target deceleration DVT2 can be calculated by multiplying the first target deceleration DVT1 by a correction value K. In this case, the correction value K is greater than "1". It is preferable that the correction value K becomes smaller as the magnitude of the first target deceleration DVT1 increases.

[0065] As another example, the second target deceleration DVT2 can be calculated by adding a correction value K to the first target deceleration DVT1. In this case, the correction value K is a value that increases the magnitude of the target deceleration, i.e., a positive value. It is preferable that the correction value K becomes smaller as the magnitude of the first target deceleration DVT1 increases.

[0066] When calculating the second target deceleration DVT2 using the correction value K, if the first target deceleration DVT1 becomes "0", the calculation of the second target deceleration DVT2 can be continued as follows. For example, the calculation of the second target deceleration DVT2 can be continued until the second target deceleration DVT2 becomes "0" by using the rate of change of the second target deceleration DVT2 just before the first target deceleration DVT1 becomes "0". For example, by pre-setting the minimum rate of change of the second target deceleration DVT2, the calculation of the second target deceleration DVT2 can also be continued until the second target deceleration DVT2 becomes "0" by using the minimum rate of change.

[0067] In the above embodiment, the manipulated amount Bp was used as an example of a braking request. The command value output by the support control device 60 when braking the vehicle 90 can also be treated as a braking request. In the above embodiment, the operation of the acceleration control member was exemplified as a request to accelerate the vehicle 90. The command value output by the support control device 60 when accelerating the vehicle 90 can also be treated as a request to accelerate the vehicle 90.

[0068] The adjustment processing unit 13 can also adjust the target deceleration based on the regeneration ratio. For example, if the regeneration ratio is equal to or greater than a specified judgment ratio, the adjustment processing unit 13 may reduce the magnitude of the rate of change of the second target deceleration DVT2, while if the regeneration ratio is less than the judgment ratio, it may not reduce the magnitude of the rate of change of the second target deceleration DVT2. For example, the above configuration can be realized when condition (B) which constitutes the starting condition includes the regeneration ratio being equal to or greater than a specified judgment ratio. The judgment ratio can be set to a value in which the proportion of friction braking force to the total braking force is large when the regeneration ratio is less than the judgment ratio. For example, the judgment ratio can be set to a value between 0.5 and 1.0.

[0069] When friction braking force accounts for a large proportion of the total braking force, the situation in which the reduction in regenerative braking force becomes steep when the braking requirement decreases is less likely to occur compared to when the proportion of regenerative braking force is large. In such cases, it is preferable to reduce the braking force in accordance with the braking requirement without adjusting the rate of change of the target deceleration. With the above configuration, it is possible to more effectively mitigate the delay in the reduction of braking force while also gradually slowing down the rate of reduction of regenerative braking force when there is a risk of vibration occurring due to the reduction in regenerative braking force.

[0070] The adjustment processing unit 13 may perform feedback processing using the regenerative braking force actually acting on the vehicle 90. The regenerative braking force actually acting on the vehicle 90 is called the effective regenerative braking force BR. The effective regenerative braking force BR can be obtained from a regenerative braking device, for example, a hybrid system 70. For example, the adjustment processing unit 13 may perform feedback processing to reduce the deviation between the amount of decrease per unit time of the requested regenerative braking force BRT and the amount of decrease per unit time of the effective regenerative braking force BR, and calculate the second target deceleration DVT2. As a specific example, the adjustment processing unit 13 can calculate the second target deceleration DVT2 using, for example, a target deceleration calculated based on a calculation map and a feedback correction term calculated by the feedback processing. According to the above configuration, the regenerative braking force can be controlled more precisely. The regenerative braking force can be controlled accurately even when the magnitude of the regenerative braking force is small.

[0071] In the above embodiment, the adjustment processing unit 13 determines whether or not the termination condition is met, and based on the determination result, the adjustment processing unit 13 delays the braking determination unit 11 from turning off the braking determination F1. Alternatively, the braking determination unit 11 may determine whether or not the termination condition is met.

[0072] The processing circuits of the vehicle control device 10, the hybrid system 70, and the support control device 60 may have any of the following configurations: [a] A circuit comprising one or more processors that perform various processes according to a computer program. The processor comprises a processing unit. Examples of processing units include a CPU, DSP, and GPU. The processor comprises memory. Examples of memory include RAM, ROM, and flash memory. Memory stores program code or instructions configured to cause the processing unit to perform the processes. Memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or dedicated computer. [b] A circuit comprising one or more hardware circuits that perform various processes. Examples of hardware circuits include an ASIC (Application Specific Integrated Circuit), a CPLD (Complex Programmable Logic Device), and an FPGA (Field Programmable Gate Array). [c] A circuit comprising a processor that performs a part of the various processes according to a computer program, and hardware circuits that perform the remaining parts of the various processes.

[0073] Some or all of the functions realized by the processing circuits of the hybrid system 70 and the support control device 60 may be realized by the vehicle control device 10. Some of the functions implemented by the vehicle control device 10 may be implemented by other processing circuits connected to the vehicle control device 10.

[0074] The vehicle control system may consist of multiple control units. Each control unit may have a processing circuit. An example will be illustrated using Figures 7 and 8.

[0075] Figure 7 shows the vehicle control device 110. The vehicle control device 110 comprises a first control unit 120 and a second control unit 130. The first control unit 120 includes, for example, a CPU 120a as a processing unit. The first control unit 120 includes, for example, a ROM 120b as memory. The second control unit 130 includes, for example, a CPU 130a as a processing unit. The second control unit 130 includes, for example, a ROM 130b as memory.

[0076] As shown in Figure 8, the first control unit 120 includes, as functional units, a braking determination unit 111, a target deceleration calculation unit 112, an adjustment processing unit 113, a friction requirement calculation unit 115, and a first control unit 118. The second control unit 130 includes, as functional units, a regenerative coordination unit 114 and a second control unit 119. The adjustment processing unit 113 can perform deceleration adjustment processing in the same manner as in the above embodiment.

[0077] The vehicle control device 110 differs from the vehicle control device 10 in the above embodiment in that the second target deceleration DVT2 calculated by the adjustment processing unit 113 in the first control unit 120 is transmitted to the regenerative coordination unit 114 in the second control unit 130.

[0078] In the first control unit 120, the friction request calculation unit 115 can calculate the first required friction braking force BPTa based on the second target deceleration DVT2. The first control unit 118 can operate the friction braking device 80 based on the first required friction braking force BPTa.

[0079] In the second control unit 130, the regenerative coordination unit 114 can calculate the second required friction braking force BPTb based on the second target deceleration DVT2. The second control unit 119 can operate the friction braking device 80 based on the second required friction braking force BPTb. The regenerative coordination unit 114 can also acquire the first required friction braking force BPTa and perform coordinated control using the first required friction braking force BPTa.

[0080] In the above embodiment, a hybrid electric vehicle was given as an example of vehicle 90. Vehicle 90 can be any vehicle equipped with a regenerative braking system. The power source of vehicle 90 is not limited. For example, vehicle 90 may be an electric vehicle powered by a motor-generator that also functions as a regenerative braking system. [Explanation of Symbols]

[0081] 10... Vehicle control system 11...Brake judgment section 12…Target deceleration calculation section 13... Adjustment Processing Unit 14...Regeneration coordination department 60...Support control device 70…Hybrid System 71…Motor Generator 72... Internal combustion engine 80...Friction braking device 90... Vehicles 91... Braking operating member

Claims

1. A vehicle control device applicable to a vehicle having a regenerative braking system that generates regenerative braking force as a braking force for braking the vehicle, and which brakes the vehicle based on a target value of the deceleration degree of the vehicle in response to a braking request for braking the vehicle, A braking determination unit that determines that the vehicle is being braked based on the braking request, When the vehicle is being braked, a target deceleration calculation unit calculates a first target deceleration as a target value for the degree of deceleration of the vehicle based on the braking request, The system includes a deceleration adjustment process that calculates the second target deceleration by adjusting the first target deceleration so that the magnitude of the rate of change of the second target deceleration is less than the magnitude of the rate of change of the first target deceleration when the first target deceleration is brought closer to "0", and an adjustment processing unit that brakes the vehicle based on the second target deceleration so that the regenerative braking force is reduced at a rate corresponding to the rate of decrease of the second target deceleration. Vehicle control system.

2. The adjustment processing unit is, In the deceleration adjustment process, if the magnitude of the rate of change of the first target deceleration is greater than the upper limit, the second target deceleration is calculated so as to adjust the magnitude of the rate of change of the second target deceleration to the same value as the upper limit. The larger the magnitude of the first target deceleration, the larger the upper limit. The vehicle control device according to claim 1.

3. The adjustment processing unit is, In the deceleration adjustment process, the second target deceleration is calculated using a correction value that corrects the first target deceleration such that the larger the magnitude of the first target deceleration, the smaller the discrepancy between the first target deceleration and the second target deceleration. The vehicle control device according to claim 1.

4. This applies to vehicles further equipped with a friction braking system that generates frictional braking force. The system includes a regenerative control unit that performs coordinated control between the frictional braking force and the regenerative braking force, The ratio of the regenerative braking force to the total braking force applied to the vehicle is defined as the regeneration ratio. The adjustment processing unit is, If the regeneration ratio is equal to or greater than the predetermined judgment ratio, the magnitude of the rate of change of the second target deceleration is made smaller than the magnitude of the rate of change of the first target deceleration, If the regeneration ratio is smaller than the determination ratio, the magnitude of the rate of change of the second target deceleration will not be smaller than the magnitude of the rate of change of the first target deceleration. A vehicle control device according to any one of claims 1 to 3.

5. The system includes a regenerative control unit that calculates the required regenerative braking force as the required value of the regenerative braking force based on the second target deceleration, The adjustment processing unit performs a feedback process to reduce the difference between the amount of decrease in the requested regenerative braking force per unit time and the amount of decrease in the regenerative braking force actually acting on the vehicle per unit time, and calculates the second target deceleration. A vehicle control device according to any one of claims 1 to 4.

6. During the execution of the deceleration adjustment process, even if the braking request is resolved, the braking of the vehicle based on the second target deceleration will continue. A vehicle control device according to any one of claims 1 to 5.

Images