JP5402578B2 - Brake control device - Google Patents

Description

  The present invention relates to a brake control device that controls braking force applied to wheels provided in a vehicle.

  Patent Document 1 describes a braking control device for an electric vehicle that performs a shift change after setting a regenerative braking force to zero when a shift operation is performed by a driver. Patent Document 2 describes a braking force control device that gradually reduces the target regenerative braking force to zero when the shift lever of the continuously variable transmission is switched to the N range when the shift of the continuously variable transmission is completed. Yes.

JP-A-11-27802 JP 2002-95104 A

  By the way, if the shift lever is operated during regenerative braking, the regenerative braking force is momentarily reduced. In general, the hydraulic braking force is inferior to the regenerative braking force in response, so it is not always easy to completely compensate for the instantaneous decrease in the regenerative braking force with the hydraulic braking force. In this case, the driver feels an instantaneous decrease in deceleration (so-called G drop shock). On the other hand, it is preferable to utilize the regenerative braking force as much as possible from the viewpoint of improving fuel consumption.

  Therefore, an object of the present invention is to provide a brake control device that can reduce the influence on the brake feeling assumed at the time of shifting while continuously using the regenerative braking force.

  A brake control device according to an aspect of the present invention includes an electric motor connected to a wheel via a speed change mechanism, a regenerative brake unit that applies a regenerative braking force to the wheel by regeneration of the electric motor, and a friction control to the wheel. And a control unit that controls the regenerative brake unit and the friction brake unit so as to generate the required braking force by using the regenerative braking force and the friction braking force in combination. The control unit determines whether or not there is a high possibility that a shift is performed, and if it is determined that the possibility is high, the control unit distributes the regenerative braking force and the friction braking force so as to leave a surplus power in the regenerative braking force. Adjust to generate the required braking force.

  According to this aspect, when there is a high possibility that a shift is performed, the distribution of the regenerative braking force and the friction braking force is adjusted so as to leave a surplus power in the regenerative braking force. For this reason, the regenerative braking force is kept at a relatively low level. When the regenerative braking force is small, the fluctuation during shifting is small. Therefore, the influence on the brake feeling at the time of shifting can be mitigated. Since the use of the regenerative braking force is continued without stopping, the influence on the fuel consumption performance can be reduced.

  The control unit may control the regenerative braking force under a lower upper limit when it is determined that the possibility of shifting is high, compared with a case where it is determined that the possibility is low. For example, a plurality of upper limit values may be set for the regenerative braking force in the control unit, and the control unit may select a lower upper limit value as the possibility of shifting is higher. For example, when two upper limit values are set, the control unit may select the lower upper limit value when it is determined that there is a high possibility that a shift is performed. In this way, by setting the low upper limit to the regenerative braking force, the regenerative braking force can be easily kept at a low level, and a so-called G drop shock can be suppressed for a very short time during shifting.

  The control unit determines whether or not the vehicle deceleration fluctuation is to be suppressed, and when it is determined that the vehicle deceleration fluctuation is to be suppressed and it is highly likely that the shift is performed, the regenerative control is performed. The distribution between the regenerative braking force and the friction braking force may be adjusted so as to leave a surplus power. In this way, the distribution adjustment between the regenerative braking force and the friction braking force can be limited to a situation where the vehicle deceleration fluctuation should be suppressed. Therefore, the influence on fuel consumption performance can be further reduced.

  A brake control device according to another aspect of the present invention includes an electric motor connected to a wheel via a speed change mechanism, and a regenerative brake unit that applies a regenerative braking force to the wheel by regeneration of the electric motor, and a friction to the wheel A friction brake unit that applies a braking force, and a controller that controls the regenerative brake unit and the friction brake unit so as to generate the required braking force by preferentially generating the regenerative braking force and compensating the shortage with the friction braking force; Is provided. The control unit determines whether or not there is a downhill on the current or forward traveling road, and when it is determined that there is a downhill, gives priority to the regenerative braking force after imposing a limit on the regenerative braking force. The shortage of the regenerative braking force with respect to the required braking force of the vehicle is compensated with the friction braking force.

  According to this aspect, the regenerative braking force is temporarily limited when trying to travel downhill. On the downhill, the driver may perform a downshift operation. In this way, by limiting the regenerative braking force in advance, it is possible to suppress a decrease in the regenerative braking force due to the downshift operation. For this reason, a so-called G drop shock can be suppressed. Further, since the regenerative braking force is continuously generated without stopping under temporary restrictions, the influence on the fuel efficiency can be reduced.

  According to the present invention, it is possible to achieve both improvement in brake feeling during shifting and utilization of regenerative braking force.

1 is a schematic configuration diagram illustrating a vehicle to which a brake control device according to an embodiment of the present invention is applied. It is a systematic diagram showing a hydraulic brake unit concerning this embodiment. It is a flowchart for demonstrating an example of a regeneration cooperation control process. It is a flowchart for demonstrating the switching process of the brake control mode which concerns on one Embodiment of this invention. It is a figure which shows an example of the time change of the braking force distribution in the fuel consumption priority mode which concerns on this embodiment. It is a figure which shows an example of the time change of the braking force distribution in G omission shock countermeasure priority mode which concerns on this embodiment.

  A brake control device according to an embodiment of the present invention includes a brake control unit that controls a regenerative braking force and a friction braking force by switching between a fuel efficiency priority mode and a G missing shock countermeasure priority mode. In one embodiment, both the fuel efficiency priority mode and the G drop shock countermeasure priority mode are premised on regenerative cooperative control in which the regenerative braking force is preferentially used and the shortage to the required braking force is compensated with the friction braking force.

  In the G missing shock countermeasure priority mode, the brake control unit adjusts the distribution of the regenerative braking force and the friction braking force so as to leave a surplus with respect to the maximum value of the regenerative braking force in the fuel efficiency priority mode. In the G missing shock countermeasure priority mode, the brake control unit limits the regenerative braking force as compared with the fuel efficiency priority mode while continuing to generate the regenerative braking force. The decrease in regenerative braking force is compensated by friction braking force. For example, when it is determined that there is a high possibility that a shift is performed, the brake control unit limits the regenerative braking force so that the regenerative braking force fluctuation during the shift is within an allowable range. On the other hand, the fuel efficiency priority mode is a control mode that maximizes the use of regenerative braking force. In the fuel efficiency priority mode, for example, the maximum value of the regenerative braking force that is allowed according to the regenerative energy absorption capability (for example, the state of charge of the battery) is set. The brake control unit controls the regenerative braking force in the G missing shock countermeasure priority mode based on an upper limit value set to a value smaller than the regenerative braking force maximum value.

  The brake control unit normally generates the required braking force in the fuel efficiency priority mode, and temporarily shifts to the G missing shock countermeasure priority mode when it is determined that the regenerative braking force can be reduced due to the shift. For example, the brake control unit controls the braking force in the G missing shock countermeasure priority mode when the driver is highly sensitive to a change in deceleration when it is assumed that there is a high possibility of shifting. For example, when it is determined that a downshift operation is predicted and the amount of braking operation by the driver is smaller than the threshold value, the brake control unit shifts to the G missing shock countermeasure priority mode. For example, when the brake control unit determines that a downhill or an uphill exceeding a predetermined gradient is ahead, or when traveling on the downhill or the uphill, the brake control unit determines that there is a high possibility that a shift is performed. May be. Instead of downhill or uphill, a curve that does not satisfy a predetermined radius of curvature may be used.

  Here, the regenerative braking force is a braking force applied to the wheel by operating an electric motor for driving the wheel as a generator that receives the rotational torque of the traveling wheel. In one embodiment, the wheel and the electric motor are connected via a power transmission path including a speed change mechanism. The transmission mechanism may be a stepped transmission in which a plurality of transmission ratios are set in stages, or may be a continuously variable transmission that can obtain an arbitrary transmission ratio within a set range. The kinetic energy of the vehicle is converted into electric energy by regenerative braking, and the electric energy is accumulated in the storage battery from the electric motor through a power conversion device including an inverter and the like. The accumulated electric energy is used for driving the wheels and the like, and contributes to improving the fuel consumption of the vehicle. The friction braking force is a braking force applied to the wheel by pressing the friction member against a rotating member that rotates with the wheel. The friction member is pressed against the rotating member by the hydraulic pressure supplied from the hydraulic pressure source.

  While performing the regenerative cooperative control, the brake control unit normally uses the regenerative braking force as much as possible in the fuel efficiency priority mode, and temporarily switches to the G missing shock countermeasure priority mode as necessary. Thereby, G omission at the time of shifting can be suppressed while suppressing the influence on fuel consumption. Further, since the regenerative braking force fluctuation at the time of shifting is reduced or prevented, the friction braking force control for compensating the regenerative braking force fluctuation is also relaxed. The frequency of hydraulic control for increasing and decreasing the friction braking force is reduced, and the service life of the hydraulic control mechanism can be extended.

  In one embodiment, a vehicle control device is provided in which torque of a motor is transmitted to wheels via a transmission. This control device includes a regenerative braking unit that regenerates a motor to obtain a regenerative braking force, a friction braking unit that obtains a friction braking force by pressurizing a friction member, and whether or not there is a high possibility of a shift change. Determining means. The control device further includes a braking force distribution adjusting unit that adjusts the distribution of the regenerative braking force and the frictional braking force so as to ensure the remaining capacity of the regenerative braking force when it is determined that the situation is highly likely. Thus, when there is a high possibility that a shift change will be performed, the G braking loss due to the shift change can be suppressed by reducing the regenerative braking force so as to ensure the reserve capacity in advance.

  In this case, the vehicle control device may determine the regenerative braking force by setting an upper limit value of the regenerative braking force of the motor. When it is determined that the shift change is highly likely to occur, the control device reduces the regenerative braking force by lowering the upper limit value of the regenerative braking force than when it is not determined that the possibility is high. May be reduced. When the regenerative braking force is small to some extent, the instantaneous decrease in the regenerative braking force at the time of shifting does not occur. For this reason, the fluctuation | variation of the regenerative braking force by a shift change can be reduced or prevented by reducing the upper limit value of the regenerative braking force in a situation where the possibility of a shift change is high.

  In one embodiment, a brake control part computes demand braking power based on a driver's brake operation, and computes demand regenerative braking power based on this demand braking power. The brake control unit transmits the requested regenerative braking force to the hybrid control unit. The hybrid control unit controls the regenerative braking force generation unit according to the received requested regenerative braking force to generate the regenerative braking force, and transmits the actually generated regenerative braking force effective value to the brake control unit. The brake control unit calculates a required friction braking force based on the required braking force and the regenerative braking force effective value, and controls the friction braking force generation unit according to the required friction braking force.

  The hybrid control unit transmits a regeneration decrease notice signal for notifying the decrease in the regenerative braking force to the brake control unit based on the state of the regenerative braking force generation unit. For example, the hybrid control unit outputs a regeneration decrease notice signal when the state of charge of the storage battery approaches full charge (for example, when the SOC exceeds a predetermined level). The brake control unit may limit the required regenerative braking force when receiving the regeneration decrease notice signal.

  The brake control unit may further determine the possibility that the regenerative braking force is reduced when the regenerative reduction notice signal is not received. For example, when it is determined that there is a high possibility that a shift will be performed, or when it is determined that a change to a different brake control mode or vehicle control mode is likely to be performed, the brake control unit You may determine with the possibility that a fall will arise. If the brake control unit determines that there is a high possibility that the regenerative braking force will decrease, the brake control unit may adjust the distribution of the regenerative braking force and the friction braking force to the first distribution, and the regenerative braking force may decrease. If it is determined that the regenerative braking force is low, the distribution of the regenerative braking force and the frictional braking force may be adjusted to the second distribution. The first distribution is set to limit the regenerative braking force compared to the second distribution.

  For example, the brake control unit determines whether or not a decrease in the regenerative braking force is predicted when the regeneration decrease notification signal is not received, and when the decrease is predicted, the G missing shock countermeasure priority mode is determined. The braking force may be controlled with. On the other hand, the brake control unit may control the braking force in the fuel efficiency priority mode when a decrease in the regenerative braking force is not predicted.

  FIG. 1 is a schematic configuration diagram illustrating a vehicle to which a brake control device according to an embodiment of the present invention is applied. A vehicle 1 shown in the figure is configured as a so-called hybrid vehicle, and includes an engine 2, a three-shaft power split mechanism 3 connected to a crankshaft that is an output shaft of the engine 2, and a power split mechanism 3. A motor generator 4 capable of generating electricity, an electric motor 6 connected to the power split mechanism 3 via a transmission 5, and an electronic control unit for hybrid (hereinafter referred to as “hybrid ECU”) that controls the entire drive system of the vehicle 1. The electronic control unit is all referred to as “ECU”). A right front wheel 9FR and a left front wheel 9FL, which are drive wheels of the vehicle 1, are connected to the transmission 5 via a drive shaft 8.

  The engine 2 is an internal combustion engine that is operated using a hydrocarbon-based fuel such as gasoline or light oil, and is controlled by the engine ECU 13. The engine ECU 13 can communicate with the hybrid ECU 7, and performs fuel injection control, ignition control, intake control, etc. of the engine 2 based on control signals from the hybrid ECU 7 and signals from various sensors that detect the operating state of the engine 2. Run. Further, the engine ECU 13 gives information regarding the operating state of the engine 2 to the hybrid ECU 7 as necessary.

  The power split mechanism 3 transmits the output of the electric motor 6 to the left and right front wheels 9FR, 9FL via the transmission 5, distributes the output of the engine 2 to the motor generator 4 and the transmission 5, and the electric motor. 6 and the speed of the engine 2 is reduced or increased. The motor generator 4 and the electric motor 6 are each connected to a battery 12 via a power converter 11 including an inverter, and a motor ECU 14 is connected to the power converter 11. As the battery 12, for example, a storage battery such as a nickel hydride storage battery can be used. The motor ECU 14 can also communicate with the hybrid ECU 7 and controls the motor generator 4 and the electric motor 6 via the power converter 11 based on a control signal from the hybrid ECU 7 or the like. The hybrid ECU 7, engine ECU 13, and motor ECU 14 described above are all configured as a microprocessor including a CPU. In addition to the CPU, a ROM that stores various programs, a RAM that temporarily stores data, and an input / output port And a communication port.

  The left and right front wheels 9FR and 9FL can be driven by the output of the electric motor 6 by supplying electric power from the battery 12 to the electric motor 6 via the power converter 11 under the control of the hybrid ECU 7 and the motor ECU 14. . Further, the vehicle 1 is driven by the engine 2 in a driving region where the engine efficiency is good. At this time, by transmitting a part of the output of the engine 2 to the motor generator 4 via the power split mechanism 3, the electric motor 6 is driven using the electric power generated by the motor generator 4 or the power conversion device 11 is operated. It is possible to charge the battery 12.

  When the vehicle 1 is braked, the electric motor 6 is rotated by the power transmitted from the front wheels 9FR and 9FL under the control of the hybrid ECU 7 and the motor ECU 14, and the electric motor 6 is operated as a generator. That is, the electric motor 6, the power converter 11, the hybrid ECU 7, the motor ECU 14, and the like function as a regenerative brake unit 10 that applies braking force to the left and right front wheels 9FR, 9FL by regenerating the kinetic energy of the vehicle 1 into electric energy. To do.

  In addition to the regenerative brake unit 10, the vehicle 1 includes a hydraulic brake unit 20 that generates a braking force by supplying hydraulic fluid from a power hydraulic pressure source 30 or the like, as shown in FIG. 2. The vehicle braking device of the present embodiment is capable of braking the vehicle 1 by executing brake regeneration cooperative control in which the regenerative brake unit 10 and the hydraulic brake unit 20 are coordinated. The vehicle 1 in the present embodiment can generate a desired braking force by using the regenerative braking force and the hydraulic braking force together by executing the brake regeneration cooperative control.

  In the hydraulic brake unit 20, the power hydraulic pressure source 30 and the hydraulic actuator 40 are controlled by a brake ECU 70 as a control unit in the present embodiment. The brake ECU 70 is configured to be able to communicate with the hybrid ECU 7 and the navigation system 80. The navigation system 80 provides the brake ECU 70 with information related to the driving situation of the vehicle. For example, the brake ECU 70 is provided with information indicating that the current or forward traveling road is a downhill, an uphill, or a curve. The brake ECU 70 is configured to be able to receive a vehicle speed signal output from the vehicle speed sensor 82.

  FIG. 2 is a system diagram showing the hydraulic brake unit 20 according to the present embodiment. As shown in FIG. 2, the hydraulic brake unit 20 includes disc brake units 21FR, 21FL, 21RR and 21RL provided for each wheel, a master cylinder unit 27, a power hydraulic pressure source 30, a hydraulic brake unit 20 Pressure actuator 40.

  Disc brake units 21FR, 21FL, 21RR, and 21RL apply braking force to the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel of the vehicle, respectively. The master cylinder unit 27 as the manual hydraulic pressure source in the present embodiment sends the brake fluid pressurized according to the operation amount by the driver of the brake pedal 24 as the brake operation member to the disc brake units 21FR to 21RL. To do. The power hydraulic pressure source 30 can send the brake fluid as the working fluid pressurized by the power supply to the disc brake units 21FR to 21RL independently from the operation of the brake pedal 24 by the driver. is there. The hydraulic actuator 40 appropriately adjusts the hydraulic pressure of the brake fluid supplied from the power hydraulic pressure source 30 or the master cylinder unit 27 and sends it to the disc brake units 21FR to 21RL. Thereby, the braking force with respect to each wheel by hydraulic braking is adjusted.

  Each of the disc brake units 21FR to 21RL, the master cylinder unit 27, the power hydraulic pressure source 30, and the hydraulic actuator 40 will be described in more detail below. Each of the disc brake units 21FR to 21RL includes a brake disc 22 and wheel cylinders 23FR to 23RL incorporated in the brake caliper, respectively. The wheel cylinders 23FR to 23RL are connected to the hydraulic actuator 40 via different fluid passages. Hereinafter, the wheel cylinders 23FR to 23RL are collectively referred to as “wheel cylinders 23” as appropriate.

  In the disc brake units 21FR to 21RL, when brake fluid is supplied to the wheel cylinder 23 from the hydraulic actuator 40, a brake pad as a friction member is pressed against the brake disc 22 that rotates together with the wheel. Thereby, a braking force is applied to each wheel. In the present embodiment, the disc brake units 21FR to 21RL are used, but other braking force applying mechanisms including a wheel cylinder 23 such as a drum brake may be used.

  In this embodiment, the master cylinder unit 27 is a master cylinder with a hydraulic booster, and includes a hydraulic booster 31, a master cylinder 32, a regulator 33, and a reservoir. The hydraulic booster 31 is connected to the brake pedal 24, amplifies the pedal effort applied to the brake pedal 24, and transmits it to the master cylinder 32. When the brake fluid is supplied from the power hydraulic pressure source 30 to the hydraulic pressure booster 31 via the regulator 33, the pedal effort is amplified. The master cylinder 32 generates a master cylinder pressure having a predetermined boost ratio with respect to the pedal effort.

  A reservoir 34 for storing brake fluid is disposed above the master cylinder 32 and the regulator 33. The master cylinder 32 communicates with the reservoir 34 when the depression of the brake pedal 24 is released. On the other hand, the regulator 33 is in communication with both the reservoir 34 and the accumulator 35 of the power hydraulic pressure source 30, and the reservoir 34 is used as a low pressure source, the accumulator 35 is used as a high pressure source, and the hydraulic pressure is approximately equal to the master cylinder pressure. Is generated. Hereinafter, the hydraulic pressure in the regulator 33 is appropriately referred to as “regulator pressure”. The master cylinder pressure and the regulator pressure do not need to be exactly the same pressure. For example, the master cylinder unit 27 can be designed so that the regulator pressure is slightly higher.

  The power hydraulic pressure source 30 includes an accumulator 35 and a pump 36. The accumulator 35 converts the pressure energy of the brake fluid boosted by the pump 36 into the pressure energy of an enclosed gas such as nitrogen, for example, about 14 to 22 MPa and stores it. The pump 36 has a motor 36 a as a drive source, and its suction port is connected to the reservoir 34, while its discharge port is connected to the accumulator 35. The accumulator 35 is also connected to a relief valve 35 a provided in the master cylinder unit 27. When the pressure of the brake fluid in the accumulator 35 increases abnormally to about 25 MPa, for example, the relief valve 35 a is opened, and the high-pressure brake fluid is returned to the reservoir 34.

  As described above, the hydraulic brake unit 20 includes the master cylinder 32, the regulator 33, and the accumulator 35 as a supply source of brake fluid to the wheel cylinder 23. A master pipe 37 is connected to the master cylinder 32, a regulator pipe 38 is connected to the regulator 33, and an accumulator pipe 39 is connected to the accumulator 35. These master pipe 37, regulator pipe 38 and accumulator pipe 39 are each connected to a hydraulic actuator 40.

  The hydraulic actuator 40 includes an actuator block in which a plurality of flow paths are formed, and a plurality of electromagnetic control valves. The flow paths formed in the actuator block include individual flow paths 41, 42, 43 and 44 and a main flow path 45. The individual flow paths 41 to 44 are respectively branched from the main flow path 45 and connected to the wheel cylinders 23FR, 23FL, 23RR, 23RL of the corresponding disc brake units 21FR, 21FL, 21RR, 21RL. Thereby, each wheel cylinder 23 can communicate with the main flow path 45.

  In addition, ABS holding valves 51, 52, 53 and 54 are provided in the middle of the individual flow paths 41, 42, 43 and 44. Each of the ABS holding valves 51 to 54 has a solenoid and a spring that are ON / OFF controlled, and both are normally open electromagnetic control valves that are opened when the solenoid is in a non-energized state. Each of the ABS holding valves 51 to 54 in the opened state can distribute the brake fluid in both directions. That is, the brake fluid can flow from the main flow path 45 to the wheel cylinder 23, and conversely, the brake fluid can also flow from the wheel cylinder 23 to the main flow path 45. When the solenoid is energized and the ABS holding valves 51 to 54 are closed, the flow of brake fluid in the individual flow paths 41 to 44 is blocked.

  Further, the wheel cylinder 23 is connected to the reservoir channel 55 via pressure reducing channels 46, 47, 48 and 49 connected to the individual channels 41 to 44, respectively. ABS decompression valves 56, 57, 58 and 59 are provided in the middle of the decompression channels 46, 47, 48 and 49. Each of the ABS pressure reducing valves 56 to 59 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. When the ABS pressure reducing valves 56 to 59 are closed, the flow of brake fluid in the pressure reducing flow paths 46 to 49 is blocked. When the solenoid is energized and the ABS pressure reducing valves 56 to 59 are opened, the brake fluid is allowed to flow through the pressure reducing flow paths 46 to 49, and the brake fluid flows from the wheel cylinder 23 to the pressure reducing flow paths 46 to 49 and It returns to the reservoir 34 via the reservoir channel 55. The reservoir channel 55 is connected to the reservoir 34 of the master cylinder unit 27 via a reservoir pipe 77.

  The main channel 45 has a separation valve 60 in the middle. By this separation valve 60, the main channel 45 is divided into a first channel 45 a connected to the individual channels 41 and 42 and a second channel 45 b connected to the individual channels 43 and 44. The first flow path 45a is connected to the front wheel wheel cylinders 23FR and 23FL via the individual flow paths 41 and 42, and the second flow path 45b is connected to the rear wheel wheel cylinder via the individual flow paths 43 and 44. Connected to 23RR and 23RL.

  The separation valve 60 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. When the separation valve 60 is in the closed state, the flow of brake fluid in the main flow path 45 is blocked. When the solenoid is energized and the separation valve 60 is opened, the brake fluid can be circulated bidirectionally between the first flow path 45a and the second flow path 45b.

  In the hydraulic actuator 40, a master channel 61 and a regulator channel 62 communicating with the main channel 45 are formed. More specifically, the master channel 61 is connected to the first channel 45 a of the main channel 45, and the regulator channel 62 is connected to the second channel 45 b of the main channel 45. The master channel 61 is connected to a master pipe 37 that communicates with the master cylinder 32. The regulator channel 62 is connected to a regulator pipe 38 that communicates with the regulator 33.

  The master channel 61 has a master cut valve 64 in the middle. The master cut valve 64 is provided on the brake fluid supply path from the master cylinder 32 to each wheel cylinder 23. The master cut valve 64 has a solenoid and a spring that are ON / OFF-controlled, and the valve closing state is guaranteed by the electromagnetic force generated by the solenoid when supplied with a prescribed control current, so that the solenoid is in a non-energized state. It is a normally open electromagnetic control valve that is opened in some cases. The master cut valve 64 in the opened state can cause the brake fluid to flow in both directions between the master cylinder 32 and the first flow path 45 a of the main flow path 45. When a prescribed control current is applied to the solenoid and the master cut valve 64 is closed, the flow of brake fluid in the master flow path 61 is interrupted.

  A stroke simulator 69 is connected to the master channel 61 via a simulator cut valve 68 on the upstream side of the master cut valve 64. That is, the simulator cut valve 68 is provided in a flow path connecting the master cylinder 32 and the stroke simulator 69. The simulator cut valve 68 has a solenoid and a spring that are ON / OFF controlled, and the valve opening state is guaranteed by the electromagnetic force generated by the solenoid upon receipt of a specified control current, and the solenoid is in a non-energized state. It is a normally closed electromagnetic control valve that is closed in some cases. When the simulator cut valve 68 is closed, the flow of brake fluid between the master flow path 61 and the stroke simulator 69 is blocked. When the solenoid is energized and the simulator cut valve 68 is opened, the brake fluid can be circulated bidirectionally between the master cylinder 32 and the stroke simulator 69.

  The stroke simulator 69 includes a plurality of pistons and springs, and creates a reaction force corresponding to the depression force of the brake pedal 24 by the driver when the simulator cut valve 68 is opened. As the stroke simulator 69, in order to improve the feeling of brake operation by the driver, it is preferable to employ one having a multistage spring characteristic.

  The regulator flow path 62 has a regulator cut valve 65 in the middle. The regulator cut valve 65 is provided on the brake fluid supply path from the regulator 33 to each wheel cylinder 23. The regulator cut valve 65 also has a solenoid and a spring that are ON / OFF controlled, and the valve closing state is guaranteed by the electromagnetic force generated by the solenoid upon receipt of a specified control current, and the solenoid is in a non-energized state. It is a normally open electromagnetic control valve that is opened in some cases. The regulator cut valve 65 that has been opened can cause the brake fluid to flow in both directions between the regulator 33 and the second flow path 45 b of the main flow path 45. When the solenoid is energized and the regulator cut valve 65 is closed, the flow of brake fluid in the regulator flow path 62 is blocked.

  In the hydraulic actuator 40, an accumulator channel 63 is also formed in addition to the master channel 61 and the regulator channel 62. One end of the accumulator channel 63 is connected to the second channel 45 b of the main channel 45, and the other end is connected to an accumulator pipe 39 that communicates with the accumulator 35.

  The accumulator flow path 63 has a pressure-increasing linear control valve 66 in the middle. Further, the accumulator channel 63 and the second channel 45 b of the main channel 45 are connected to the reservoir channel 55 via the pressure-reducing linear control valve 67. The pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 each have a linear solenoid and a spring, and both are normally closed electromagnetic control valves that are closed when the solenoid is in a non-energized state. In the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67, the opening degree of the valve is adjusted in proportion to the current supplied to each solenoid.

  The pressure-increasing linear control valve 66 is provided as a common pressure-increasing control valve for each of the wheel cylinders 23 provided corresponding to each wheel. Similarly, the pressure-reducing linear control valve 67 is provided as a pressure-reducing control valve common to the wheel cylinders 23. That is, in this embodiment, the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 are a pair of common control valves that control the supply and discharge of the working fluid sent from the power hydraulic pressure source 30 to each wheel cylinder 23. It is provided as. Thus, if the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are made common to each wheel cylinder 23, it is preferable from the viewpoint of cost as compared with the case where a linear control valve is provided for each wheel cylinder 23.

  Here, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 corresponds to the differential pressure between the pressure of the brake fluid in the accumulator 35 and the pressure of the brake fluid in the main flow path 45, and the inlet / outlet of the pressure-reducing linear control valve 67. The pressure difference therebetween corresponds to the pressure difference between the brake fluid pressure in the main flow path 45 and the brake fluid pressure in the reservoir 34. Further, the electromagnetic driving force according to the power supplied to the linear solenoid of the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67 is F1, the spring biasing force is F2, and the pressure increasing linear control valve 66 and the pressure reducing linear control valve are Assuming that the differential pressure acting force according to the differential pressure between the inlet / outlet of 67 is F3, the relationship F1 + F3 = F2 is established. Therefore, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 is controlled by continuously controlling the power supplied to the linear solenoids of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. can do.

  In the hydraulic brake unit 20, the power hydraulic pressure source 30 and the hydraulic actuator 40 are controlled by a brake ECU 70 as a control unit in the present embodiment. The brake ECU 70 is configured as a microprocessor including a CPU, and includes a ROM that stores various programs, a RAM that temporarily stores data, an input / output port, a communication port, and the like in addition to the CPU. The brake ECU 70 can communicate with the host hybrid ECU 7 and the like, and configures the pump 36 of the power hydraulic pressure source 30 and the hydraulic actuator 40 based on control signals from the hybrid ECU 7 and signals from various sensors. The electromagnetic control valves 51 to 54, 56 to 59, 60, and 64 to 68 are controlled.

  Further, a regulator pressure sensor 71, an accumulator pressure sensor 72, and a control pressure sensor 73 are connected to the brake ECU 70. The regulator pressure sensor 71 detects the pressure of the brake fluid in the regulator flow path 62 on the upstream side of the regulator cut valve 65, that is, the regulator pressure, and gives a signal indicating the detected value to the brake ECU 70. The accumulator pressure sensor 72 detects the pressure of the brake fluid in the accumulator flow path 63, that is, the accumulator pressure on the upstream side of the pressure increasing linear control valve 66, and gives a signal indicating the detected value to the brake ECU 70. The control pressure sensor 73 detects the pressure of the brake fluid in the first flow path 45a of the main flow path 45, and gives a signal indicating the detected value to the brake ECU 70. The detection values of the pressure sensors 71 to 73 are sequentially given to the brake ECU 70 every predetermined time, and are stored and held in a predetermined storage area of the brake ECU 70.

  When the separation valve 60 is opened and the first flow path 45 a and the second flow path 45 b of the main flow path 45 communicate with each other, the output value of the control pressure sensor 73 is the low pressure of the pressure-increasing linear control valve 66. This indicates the hydraulic pressure on the high pressure side of the pressure-reducing linear control valve 67 and the output value can be used to control the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. When the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are closed and the master cut valve 64 is opened, the output value of the control pressure sensor 73 indicates the master cylinder pressure. Further, the separation valve 60 is opened so that the first flow path 45a and the second flow path 45b of the main flow path 45 communicate with each other, and the ABS holding valves 51 to 54 are opened, while the ABS pressure reducing valves 56 are opened. When? 59 is closed, the output value of the control pressure sensor 73 indicates the working fluid pressure acting on each wheel cylinder 23, i.e., the wheel cylinder pressure.

  Further, the sensor connected to the brake ECU 70 includes a stroke sensor 25 provided on the brake pedal 24. The stroke sensor 25 detects a pedal stroke as an operation amount of the brake pedal 24 and gives a signal indicating the detected value to the brake ECU 70. The output value of the stroke sensor 25 is also sequentially given to the brake ECU 70 every predetermined time, and is stored and held in a predetermined storage area of the brake ECU 70. A brake operation state detection unit other than the stroke sensor 25 may be provided in addition to the stroke sensor 25 or in place of the stroke sensor 25 and connected to the brake ECU 70. Examples of the brake operation state detection means include a pedal depression force sensor that detects an operation force of the brake pedal 24 and a brake switch that detects that the brake pedal 24 is depressed.

  The brake control device according to the present embodiment including the hydraulic brake unit 20 configured as described above can execute brake regeneration cooperative control. FIG. 3 is a flowchart for explaining an example of the regeneration cooperative control process. In response to the braking request, the brake ECU 70 starts processing. The braking request is generated when a braking force should be applied to the vehicle, for example, when the driver operates the brake pedal 24. The brake ECU 70 is repeatedly executed at a predetermined control cycle until, for example, the operation of the brake pedal 24 is released. The brake ECU 70 executes the process shown in FIG. 3 on the assumption that the conditions for permitting the regenerative cooperative control are satisfied.

  In response to the braking request, the brake ECU 70 calculates a target deceleration, that is, a required braking force (S10). For example, the brake ECU 70 calculates a target deceleration based on the measured values of the master cylinder pressure and the stroke. Here, the brake ECU 70 calculates the target braking force of each wheel by distributing the target deceleration to each wheel according to the desired braking force distribution, and in the subsequent processing, the regenerative braking force and the hydraulic braking force are based on the target braking force. May be controlled.

  The brake ECU 70 calculates the required regenerative braking force based on the target deceleration (S12). For example, the brake ECU 70 sets the target deceleration as the required regenerative braking force when the target deceleration is smaller than the maximum regenerative braking force that can be generated, and the maximum regenerative braking force when the target deceleration is equal to or greater than the maximum regenerative braking force. Is the required regenerative braking force. Further, the brake ECU 70 may calculate the required regenerative braking force by correcting the target deceleration instead of using the target deceleration as it is as the required regenerative braking force. The required regenerative braking force may be corrected to be higher with respect to the target deceleration, or may be corrected to be lower. For example, when the regeneration decrease notice signal is received, the brake ECU 70 may perform correction so as to limit the required regenerative braking force. The brake ECU 70 transmits the calculated required regenerative braking force to the hybrid ECU 7 (S14). The brake ECU 70 and the hybrid ECU 7 are connected to the in-vehicle network. The brake ECU 70 transmits the requested regenerative braking force to the in-vehicle network.

  The hybrid ECU 7 receives the requested regenerative braking force from the in-vehicle network. The hybrid ECU 7 controls the regenerative brake unit 10 with the received regenerative braking force received as the regenerative braking force target value. As a result, the hybrid ECU 7 transmits the effective value of the regenerative braking force actually generated to the brake ECU 70 through the in-vehicle network. Further, the hybrid ECU 7 may transmit a regeneration decrease notice signal to the brake ECU 70 based on the state of charge of the battery 12.

  The brake ECU 70 receives the regenerative braking force effective value from the hybrid ECU 7 (S16). The brake ECU 70 calculates a required hydraulic braking force that is a braking force to be generated by the hydraulic brake unit 20 by subtracting the regenerative braking force effective value from the target deceleration (S18). The brake ECU 70 calculates the target hydraulic pressure of each wheel cylinder 23FR to 23RL based on the required hydraulic braking force. The brake ECU 70 may correct the required hydraulic braking force or the target hydraulic pressure. The brake ECU 70 controls the hydraulic actuator 40 so that the wheel cylinder pressure becomes the target hydraulic pressure (S20). The brake ECU 70 determines the value of the control current supplied to the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 by feedback control, for example.

  As a result, in the hydraulic brake unit 20, the brake fluid is supplied from the power hydraulic pressure source 30 to each wheel cylinder 23 via the pressure-increasing linear control valve 66, and braking force is applied to the wheels. Further, brake fluid is discharged from each wheel cylinder 23 through the pressure-reducing linear control valve 67 as necessary, and the braking force applied to the wheel is adjusted. In the present embodiment, a wheel cylinder pressure control system is configured including the power hydraulic pressure source 30, the pressure-increasing linear control valve 66, the pressure-decreasing linear control valve 67, and the like. A so-called brake-by-wire braking force control is performed by the wheel cylinder pressure control system. The wheel cylinder pressure control system is provided in parallel to the brake fluid supply path from the master cylinder unit 27 to the wheel cylinder 23.

  When brake-by-wire braking force control is performed, the brake ECU 70 closes the regulator cut valve 65 so that the brake fluid delivered from the regulator 33 is not supplied to the wheel cylinder 23. Further, the brake ECU 70 closes the master cut valve 64 and opens the simulator cut valve 68. This is because the brake fluid sent from the master cylinder 32 in accordance with the operation of the brake pedal 24 by the driver is supplied not to the wheel cylinder 23 but to the stroke simulator 69. During the brake regeneration cooperative control, a differential pressure corresponding to the magnitude of the regenerative braking force acts between the upstream and downstream of the regulator cut valve 65 and the master cut valve 64.

  In the above-described brake regenerative cooperative control, the regenerative braking force is preferentially generated and the shortage of the regenerative braking force with respect to the required braking force is compensated with the friction braking force. The present invention is not limited to such a regeneration priority mode. For example, the control unit may control the braking force in a regeneration assist mode in which the regenerative braking force is used supplementarily, or distributes the target deceleration to the distribution of the preset regeneration target value and friction target value, The braking force may be controlled in a regenerative combined mode that generates a regenerative braking force and a friction braking force.

  FIG. 4 is a flowchart for explaining a brake control mode switching process according to an embodiment of the present invention. In the present embodiment, the brake ECU 70 switches from the fuel efficiency priority mode to the G missing shock countermeasure priority mode when the G missing shock countermeasure priority condition is satisfied. The brake ECU 70 executes regenerative cooperative control shown in FIG. 3 in the fuel efficiency priority mode. In the G missing shock countermeasure priority mode, the regenerative cooperative control shown in FIG. 3 is executed after setting a limit on the required regenerative braking force as compared with the fuel efficiency priority mode. The brake ECU 70 returns from the G missing shock countermeasure priority mode to the fuel efficiency priority mode when the G missing shock countermeasure priority condition is no longer satisfied.

  As shown in FIG. 4, the brake ECU 70 determines whether or not there is a driving situation where there is a high possibility that a shift operation will be performed (S30). Specifically, it is determined whether or not there is a driving situation where there is a high possibility that a downshift operation from the D range to the B range is performed. The D range is a recommended shift position in normal driving, and the B range is a shift position to be selected when the driver needs engine brake (including regenerative braking) stronger than normal driving.

  For example, the brake ECU 70 determines whether or not there is a downhill, an uphill, or a curve on the traveling road ahead based on information from the navigation system 80. The determination may be based on the information from the navigation system 80 or based on the output of an angle sensor (not shown) instead. It can be appropriately determined empirically or experimentally as to which road it can be said that the shift operation is highly likely to be performed.

  When it is determined that the driving state is highly likely to be shifted (Y in S30), the brake ECU 70 determines whether or not the driver is in a brake operating state in which the G-out sensitivity is high ( S32). It is known that when the amount of brake operation is small during low speed traveling, the driver's sensitivity to the deceleration fluctuation is high. For this reason, the brake ECU 70 determines whether or not the vehicle speed is equal to or lower than the predetermined vehicle speed and the brake operation amount is equal to or lower than the predetermined amount. The vehicle speed is determined from the measured value of the vehicle speed sensor 82, and the brake operation amount is determined from the measured value of the stroke sensor 25 or the regulator pressure sensor 71. Here, the threshold values of the vehicle speed and the brake operation amount can be appropriately determined empirically or experimentally depending on the ease of the driver's feeling of missing G.

  When it is determined that the driving situation is not likely to be shifted (N in S30), or when it is determined that the driver is not in a brake operating state with a high G-out sensitivity (N in S32). The brake ECU 70 performs normal regenerative cooperative control (S38).

  On the other hand, when it is determined that the vehicle is in a driving situation in which there is a high possibility of a shift operation and the driver is in a brake operating state with a high sensitivity for missing G (Y in S32), the brake ECU 70 determines the required regenerative braking force. An upper limit value is set to (S34). For example, the brake ECU 70 changes the upper limit value to a value lower than the maximum value of the required regenerative braking force determined in normal regenerative cooperative control. For example, the reduced upper limit value is set to a value obtained by subtracting the regenerative braking force reduction amount assumed during the shift operation from the maximum value of the required regenerative braking force. In this case, the reduced upper limit value is set to a constant value.

  The upper limit value may not be set to a constant value, and may be set to a predetermined ratio of the required regenerative braking force, for example. In this case, the reduced upper limit value is linked to the normal required regenerative braking force. Further, instead of imposing a limit on the value of the required regenerative braking force, an upper limit may be set for the time change rate of the required regenerative braking force.

  The brake ECU 70 executes regenerative cooperative control under the reduced regenerative braking force upper limit value (S36). That is, when the requested regenerative braking force calculated based on the requested braking force exceeds the regenerative braking force upper limit value, the brake ECU 70 limits the requested regenerative braking force to the upper limit value and transmits it to the hybrid ECU 7. The hybrid ECU 7 generates a regenerative braking force according to the received requested regenerative braking force.

  The G missing shock countermeasure priority condition for switching to the G missing shock countermeasure priority mode may be updated. The brake ECU 70 may adjust the G slipping shock countermeasure priority condition based on the actual shift operation frequency of the driver. The brake ECU 70 stores, for example, a traveling state and a driving state at the time of a shift operation during traveling as a driving history, and adjusts the conditions based on the driving history. For example, the brake ECU 70 may determine whether or not the frequency of the shift change is lower than a reference, and if it is determined that the frequency is low, the condition may be made stricter. When the frequency of shift changes is lower than the reference, the brake ECU 70 may increase the gradient threshold value of the travel path or adjust the threshold value of the vehicle speed or the brake operation amount to be small. In this way, when the frequency of shift changes is low, application of the G missing shock countermeasure priority mode can be limited and the application range of the fuel efficiency priority mode can be expanded, which is preferable from the viewpoint of improving fuel efficiency.

  FIG. 5 is a diagram illustrating an example of a temporal change in braking force distribution in the fuel efficiency priority mode according to the present embodiment. FIG. 5 shows the total braking force and the regenerative braking force. As described above, the remainder obtained by subtracting the regenerative braking force from the required braking force is the hydraulic braking force. Therefore, the sum of the regenerative braking force and the hydraulic braking force is the total braking force. In FIG. 5, the vertical axis indicates the braking force, and the horizontal axis indicates the elapsed time from the braking request. FIG. 5 shows the braking force rising when the brake pedal 24 is initially depressed. As an example of the time change of the required braking force, the braking request linearly increases from point A (time ta), point B (time tb), and point C (time tc), and is constant after point C (time tc). An example is shown.

  As shown in FIG. 5, the regenerative braking force target value increases in accordance with the required braking force until the initial point A (time ta) of braking. After point A (time ta), the brake ECU 70 limits the gradient of the regenerative braking force target value. This is because, for example, the brake ECU 70 has received the regeneration decrease notice signal when the battery 12 is almost fully charged. When the required braking force does not satisfy the regenerative braking force target value, the brake ECU 70 controls the hydraulic brake unit 20 to compensate for the shortage by the hydraulic braking force.

  In the example shown in FIG. 5, at the point B (time tb), the driver shifts from the D range to the B range. For this reason, the regenerative braking force instantaneously decreases and is restored to the original level after the shift change is completed. In general, the control response of the hydraulic brake unit 20 is set to be smaller than the regenerative braking force. Therefore, it is difficult to completely compensate the fluctuation of the regenerative braking force due to the shift change with the hydraulic braking force. Therefore, as shown in FIG. 5, the total braking force also decreases momentarily as the regenerative braking force decreases. This is perceived by the driver as missing G.

  FIG. 6 is a diagram illustrating an example of a time change of the braking force distribution in the G missing shock countermeasure priority mode according to the present embodiment. In FIG. 6, as in FIG. 5, the vertical axis indicates the braking force, and the horizontal axis indicates the elapsed time from the braking request. For comparison, a history of required braking force similar to that shown in FIG. 5 is shown. That is, an example is shown in which it increases linearly from the braking request and becomes constant thereafter. A broken line indicates the regenerative braking force in FIG.

  In the G drop shock countermeasure priority mode shown in FIG. 6, the increasing gradient of the regenerative braking force is reduced as compared with the fuel efficiency priority mode shown in FIG. The increase in regenerative braking force in the G missing shock countermeasure priority mode is delayed compared to the fuel efficiency priority mode. Thus, when the regenerative braking force is kept small, even if a shift operation is performed, fluctuations in the regenerative braking force can be prevented. In the example shown in FIG. 6, the regenerative braking force is limited so that the regenerative braking force during the shift operation is prevented. However, if importance is attached to the fuel efficiency, a gentler restriction may be imposed. . In other words, the regenerative braking force limit may be strengthened when emphasizing countermeasures for the G missing shock, and the limit may be relaxed when emphasizing fuel efficiency.

  In FIG. 6, the G missing shock countermeasure priority condition is not satisfied at the point D (time td), and the fuel efficiency priority mode is restored. By adjusting the distribution so that the regenerative braking force is gradually increased and the hydraulic brake force is gradually decreased from the point D (time td) to the point E (time te), the distribution is restored to the distribution of the regenerative braking force and the hydraulic braking force in the fuel efficiency priority mode. ing. Thus, returning to the fuel consumption priority mode after taking a certain amount of time is preferable for good brake feeling. The increasing gradient of the regenerative braking force is determined based on the response of the hydraulic braking force. In addition, when importance is attached to fuel consumption performance, the regenerative braking force may be rapidly recovered along with the failure of the G missing shock countermeasure priority condition.

  5 and 6 show a case where the shift operation is performed while the brake pedal is stepped on in the early stage of braking, but the same applies when the pedal operation amount is depressed relatively large in the later stage of braking. It is. The brake ECU 70 limits the regenerative braking force and increases the hydraulic braking force when the G drop shock countermeasure priority condition is satisfied. At this time, if the regenerative braking force has already exceeded the upper limit in the G loss shock countermeasure priority mode, the regenerative braking force is gradually decreased to the upper limit and the hydraulic braking force is gradually increased.

  According to the present embodiment, the regenerative braking force is limited more than usual only in a specific driving state in which the driver's shift operation is predicted and G missing is easily detected. For this reason, G omission at the time of a shift change can be reduced or prevented while minimizing the influence on fuel consumption. Further, in response to the suppression of the regenerative braking force fluctuation at the time of the shift change, the fluctuation of the hydraulic braking force for compensating the regenerative braking force fluctuation is also suppressed. For this reason, the frequency of opening and closing of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 for controlling the hydraulic pressure is reduced, and the service life of the hydraulic brake unit 20 can be increased.

  7 Hybrid ECU, 10 Regenerative brake unit, 20 Hydraulic brake unit, 23 Wheel cylinder, 27 Master cylinder unit, 32 Master cylinder, 33 Regulator, 34 Reservoir, 60 Separation valve, 65 Regulator cut valve, 66 Booster linear control valve, 67 pressure-reducing linear control valve, 70 brake ECU, 73 control pressure sensor.

Claims (3)

A regenerative brake unit that includes an electric motor connected to the wheel via a speed change mechanism, and applies a regenerative braking force to the wheel by regenerative of the electric motor;
A friction brake unit for applying a friction braking force to the wheel;
A controller that controls the regenerative brake unit and the friction brake unit so as to generate the required braking force by using the regenerative braking force and the friction braking force together,
The control unit determines whether or not the driver's speed change operation is likely to be performed, determines whether or not the vehicle deceleration fluctuation should be suppressed,
Wherein, when the likelihood is determined that the situation should be suppressed coincide with high vehicle deceleration change, the regenerative braking force under the lower limit in comparison with the case where it is determined not to be the situation by controlling the brake control apparatus characterized by generating the adjustment to the required braking force distribution between the regenerative braking force and the frictional braking force to leave surplus regenerative braking force. The determination as to whether or not the vehicle deceleration fluctuation should be suppressed includes determining whether or not a driver's braking operation amount is smaller than a threshold value. The brake control device described in 1. The control unit controls the regenerative brake unit and the friction brake unit so as to generate the required braking force to compensate for shortage in frictional braking force is generated in favor of regenerative braking force,
Determining whether the driver's gear shifting operation is likely to be performed includes determining whether there is a downhill on the current or forward travel path,
Wherein, when it is determined that the current or Ru situation der to be suppressed under Risakagaa Li Kui vehicle deceleration change forward running path of the regenerative braking force priority under the upper limit The brake control device according to claim 1 or 2, wherein the braking control device compensates for a shortage of the regenerative braking force with respect to the required braking force of the vehicle by a friction braking force.

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