JP2011110947A - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proper brake fluid pressure even when the pressure accumulation of an accumulator falls below a reference. <P>SOLUTION: A brake control device 20 includes: a pump 36 for storing a hydraulic fluid in the accumulator 35; a first supply route to supply the hydraulic fluid stored in the accumulator 35 to a wheel cylinder 23; a bypass 82 to supply the hydraulic fluid, delivered by the pump 36, to the wheel cylinder 23; a selector valve 80 that switches between the first supply route and the bypass 82 in order to supply the hydraulic fluid to the wheel cylinder 23 via either the first supply route or the bypass 82; and a brake ECU 70 that determines whether the pressure accumulation of the accumulator 35 satisfies criteria, and controls the selector valve 80 to select the first supply route when the criteria are fulfilled and to select the bypass 82 when the criteria is not fulfilled. <P>COPYRIGHT: (C)2011,JPO&INPIT

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 brake device that prohibits anti-skid control using the hydraulic pressure of an accumulator as a pressure source when the accumulator pressure is insufficient.

JP 2002-356152 A

  In a brake system using an accumulator as a hydraulic pressure source, the accumulated pressure of the accumulator may be greatly consumed when the brake operation is frequently performed or when a fade phenomenon occurs. Due to the structure of the accumulator, the hydraulic pressure does not rise until the hydraulic fluid has accumulated to some extent. In this case, there is a possibility that the provision of the brake fluid pressure by the accumulator is temporarily limited until the accumulator pressure is recovered.

  Therefore, an object of the present invention is to provide an appropriate brake fluid pressure continuously even when the accumulator pressure falls below a reference.

  A brake control device according to an aspect of the present invention includes a pump for accumulating hydraulic fluid in an accumulator, a first supply path for supplying hydraulic fluid accumulated in the accumulator to a wheel cylinder, and the pump delivering the hydraulic fluid A second supply path for supplying hydraulic fluid to the wheel cylinder; and the first supply path and the second supply so as to supply the hydraulic fluid to the wheel cylinder through one of the first supply path and the second supply path. A switching mechanism for switching between supply paths and whether or not the accumulator pressure accumulation satisfies a standard is determined. If the standard is satisfied, the first supply path is selected, and if the standard is less than the standard, the second supply is selected. A control unit that controls the switching mechanism to select a route.

  According to the present invention, it is possible to provide an appropriate brake fluid pressure even when the accumulator pressure falls below a reference.

It is a distribution diagram showing a brake control device concerning one embodiment of the present invention. It is a systematic diagram which shows the brake control apparatus which concerns on one modification of this invention.

  FIG. 1 is a system diagram showing a brake control device 20 according to an embodiment of the present invention. A brake control device 20 shown in the figure constitutes an electronically controlled brake system (ECB) for a vehicle, and controls braking force applied to four wheels provided on the vehicle. The brake control device 20 according to the present embodiment is mounted on, for example, a hybrid vehicle that includes an electric motor and an internal combustion engine as a travel drive source. In such a hybrid vehicle, each of regenerative braking that brakes the vehicle by regenerating kinetic energy of the vehicle into electric energy and hydraulic braking by the brake control device 20 can be used for braking the vehicle. The vehicle in the present embodiment can execute brake regenerative cooperative control that generates a desired braking force by using both the regenerative braking and the hydraulic braking together.

  As shown in FIG. 1, the brake control device 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 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 via the switching valve 80.

  The switching valve 80 has a solenoid and a spring that are ON / OFF controlled, and connects the pump 36 and the accumulator 35 when the solenoid is in a non-energized state, and turns off the pump 36 when the solenoid is in an energized state. Connect to bypass path 82. Therefore, when the solenoid of the switching valve 80 is not energized (in the case of illustration), accumulation of pressure from the pump 36 to the accumulator 35 is allowed, and hydraulic fluid is directly supplied from the pump 36 to the wheel cylinder 23 through the bypass path 82 when energized. can do.

  Instead of providing the single switching valve 80, two switching valves that are provided in parallel downstream of the pump 36 and that open and close in conjunction with each other may be provided as a switching mechanism. For example, one on-off valve is provided on the path from the discharge port of the pump 36 to the accumulator 35, and the other on-off valve is provided on the path from the discharge port of the pump 36 to the bypass path 82. When opening one on-off valve, the brake ECU 70 opens and closes the two on-off valves so as to close the other on-off valve.

  The accumulator pressure is maintained within a set range to be maintained by the pump 36 (this may be referred to as an allowable range in the present specification). Based on the measurement value of the accumulator pressure sensor 72, the brake ECU 70 turns on the pump 36 to increase the accumulator pressure when the accumulator pressure falls below the lower limit of the allowable range, and when the accumulator pressure exceeds the upper limit of the allowable range. The pressurization is finished by turning off the pump 36.

  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 brake control device 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. Further, by operating the switching valve 80, the pump 36 can be used as a brake fluid supply source for the wheel cylinder 23 instead of the accumulator 35.

  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. Further, a bypass pipe 84 is connected to the power hydraulic pressure source 30. These master pipe 37, regulator pipe 38, accumulator pipe 39, and bypass pipe 84 are each connected to the 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 the wheel cylinders 23, it is preferable from the viewpoint of cost as compared to providing a linear control valve 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 of 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.

  The hydraulic actuator 40 is further formed with a main bypass passage 86, a first bypass passage 88 and a second bypass passage 90. One end of the main bypass channel 86 is connected to the bypass pipe 84, and the other end is branched into a first bypass channel 88 and a second bypass channel 90. The first bypass channel 88 is connected to the first channel 45 a of the main channel 45, and the second bypass channel 90 is connected to the second channel 45 b of the main channel 45. In addition, when the hydraulic pressure direct introduction to the front system by the pump 36 is not necessary, only the main bypass channel 86 and the second bypass channel 90 may be provided without providing the first bypass channel 88.

  In the brake control device 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 a host hybrid ECU (not shown) and the like, and based on control signals from the hybrid ECU and signals from various sensors, the pump 36 and the switching valve 80 of the power hydraulic pressure source 30. Or, the electromagnetic control valves 51 to 54, 56 to 59, 60, and 64 to 68 constituting the hydraulic actuator 40 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. In the present embodiment, the stroke sensor 25 has two contact points, and can output two measured values to the brake ECU 70 as if they seemed to be two sensors.

  The brake control device 20 configured as described above can execute brake regeneration cooperative control. The brake control device 20 starts braking in response to a braking request. 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. In response to the braking request, the brake ECU 70 calculates a required braking force, and calculates a required hydraulic braking force that is a braking force to be generated by the brake control device 20 by subtracting the braking force due to regeneration from the required braking force. Here, the effective value of the braking force by regeneration is supplied from the hybrid ECU to the brake control device 20. Then, the brake ECU 70 calculates the target hydraulic pressure of each wheel cylinder 23FR to 23RL based on the calculated required hydraulic braking force. 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 based on the feedback control law so that the wheel cylinder pressure becomes the target hydraulic pressure.

  The brake control device 20 according to the present embodiment can naturally control the braking force by the wheel cylinder pressure control system even when the required braking force is provided only by the hydraulic braking force without using the regenerative braking force. . Regardless of whether or not the brake regeneration cooperative control is executed, the control mode for controlling the braking force by the wheel cylinder pressure control system will be appropriately referred to as a “linear control mode” below. Or it may be called control by brake-by-wire.

  As a result, in the brake control device 20, the brake fluid is supplied from the power hydraulic pressure source 30 to the wheel cylinders 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 first hydraulic fluid supply path is configured including the pressure-increasing linear control valve 66, the pressure-decreasing linear control valve 67, and the like. The first hydraulic fluid supply path supplies hydraulic fluid to the wheel cylinder 23 using the accumulator 35 as a hydraulic pressure source. The brake control device 20 according to the present embodiment can naturally control the braking force by the wheel cylinder pressure control system even when the required braking force is provided only by the hydraulic braking force without using the regenerative braking force. .

  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. The brake ECU 70 opens the separation valve 60. Thereby, each wheel cylinder pressure is controlled to a common hydraulic pressure.

  The brake ECU 70 determines whether or not the accumulated pressure of the accumulator 35 satisfies a standard, and does not energize the switching valve 80 when the standard is satisfied. In this case, the wheel cylinder pressure is controlled by the above-described linear control mode. On the other hand, the brake ECU 70 energizes the switching valve 80 when the accumulated pressure in the accumulator 35 falls below the reference. Thereby, the connection destination of the pump 36 is switched from the accumulator 35 to the bypass path 82. For this reason, the brake fluid sent out by the pump 36 can be directly supplied to the wheel cylinder 23.

  Here, the accumulator pressure reference for switching to the bypass path 82 by the switching valve 80 is appropriately determined experimentally or empirically based on, for example, the accumulator boosting capability of the pump 36 and the maximum hydraulic fluid outflow speed assumed for the accumulator 35. Can be set. For example, when the amount of liquid consumed by the accumulator 35 (ie, the amount delivered from the accumulator 35 to the wheel cylinder 23) exceeds the amount of hydraulic fluid discharged from the pump 36 (ie, the amount supplied per unit time to the accumulator 35), the brake ECU 70 The switching valve 80 is switched to the bypass path 82.

  In addition, the brake ECU 70 switches the switching valve 80 to the bypass path 82 when the boosting capacity of the pump 36 is expected to be insufficient to prevent the accumulator pressure from falling below the desired minimum pressure during braking. Also good. For example, the brake ECU 70 may switch the switching valve 80 to the bypass path 82 when braking is performed while the accumulator pressure recovery by the pump 36 is being performed. In particular, the brake ECU 70 may switch the switching valve 80 to the bypass path 82 when a fade phenomenon occurs or when braking is repeatedly performed exceeding a predetermined frequency during the recovery of the accumulator pressure by the pump 36. .

  In this way, the brake fluid is directly supplied from the pump 36 to the wheel cylinder 23 when the accumulated pressure in the accumulator is temporarily consumed greatly, such as when the brake operation is frequently performed or when a fade phenomenon occurs. can do. Therefore, even when the accumulated pressure of the accumulator falls below the reference, an appropriate brake fluid pressure can be continuously provided. It is also possible to reduce vehicle weight and cost by reducing the size of the corner brake. Further, since the brake fluid pressure can be provided alternatively by the pump 36, the accumulator 35 can be downsized.

  In the present embodiment, a cut valve may be provided in at least one of the first bypass channel 88 and the second bypass channel 90. This cut valve is, for example, a normally open electromagnetic control valve, and shuts off the bypass flow path when energized. By providing the cut valve, the hydraulic fluid pressure can be directly introduced from the pump 36 selectively into one of two systems (front system and rear system in this embodiment).

  For example, by providing a cut valve in the second bypass passage 90, when an abnormality such as liquid leakage occurs in the rear system, the rear system can be separated from the pump 36 and only the front system can be assisted by the pump 36. . When the rear system is abnormal, the supply of hydraulic fluid from the accumulator 35 to the front system is shut off by the separation valve 60. According to the present embodiment, the braking force can be generated by adding the assisting hydraulic pressure of the pump 36 to the front-side hydraulic fluid pressure generated by the driver's stepping force. Therefore, it is possible to increase the degree of freedom in designing the front-side manual brake system while ensuring the required braking force. For example, the master cylinder volume and the pedal depression force assist mechanism can be reduced in size.

  Similarly, by providing a cut valve in the first bypass flow path 88, when an abnormality such as liquid leakage occurs in the front system, the front system is separated from the pump 36 and only the rear system is assisted by the pump 36. it can. In order to generate a sufficient braking force only with the rear system, it is necessary to increase the rear axle load distribution. According to this embodiment, the rear system can be assisted by the pump 36, so that the degree of freedom in designing the front / rear weight distribution of the vehicle can be increased.

  In addition, the switching valve 80 may be omitted by providing a cut valve in both the first bypass channel 88 and the second bypass channel 90. In this case, the cut valve is preferably a normally closed electromagnetic control valve. Thus, instead of configuring the single switching valve 80 as a switching mechanism, a switching mechanism may be configured by providing a plurality of cut valves on the bypass path 82.

  FIG. 2 is a system diagram showing a brake control device 20 according to a modification of the present invention. In the embodiment shown in FIGS. 1 and 2, the brake ECU 70 determines whether or not the accumulated pressure of the accumulator 35 satisfies a standard, and when it falls below the standard, the hydraulic fluid directly from the pump 36 to the wheel cylinder 23 is switched by the switching valve 80. The point of switching to supply is common. Therefore, in the embodiment shown in FIG. 2, the description of the configuration common to the embodiment shown in FIG.

  This modification is different from the embodiment shown in FIG. 1 in that a bypass path 82 is connected to a liquid path that connects the accumulator 35 to the pressure-increasing linear control valve 66. As shown in FIG. 2, the bypass path 82 is connected to the accumulator pipe 39. Thus, even if the bypass path 82 is connected downstream of the accumulator 35, the hydraulic fluid can be directly supplied from the pump 36 to the wheel cylinder 23 via the pressure-increasing linear control valve 66.

  In this case, the hydraulic fluid can be directly supplied from the pump 36 to both of the two systems by opening the separation valve 60. Further, by closing the separation valve 60, the front system can be shut off from the pump 36, and the hydraulic fluid can be directly supplied from the pump 36 only to the rear system. Therefore, the brake ECU 70 may control the pump 36 so as to shut off the separation valve 60 and supply the hydraulic fluid directly to the rear system when an abnormality is detected in the front system.

  Further, as shown in FIG. 2, an on-off valve 92 is provided upstream of the connection position of the bypass path 82 in the accumulator pipe 39 (that is, on the regulator side). The on-off valve 92 is, for example, a normally open type electromagnetic control valve. The brake ECU 70 opens and closes the opening / closing valve 92 in conjunction with the switching of the switching valve 80. That is, the brake ECU 70 opens the opening / closing valve 92 when the switching valve 80 connects the pump 36 to the accumulator 35, and closes the opening / closing valve 92 when the switching valve 80 connects the pump 36 to the bypass path 82. . In this way, when the wheel cylinder 23 is directly pressurized by the pump 36, it is possible to prevent the hydraulic fluid from flowing out from the pump 36 to the regulator 33 and reduce the amount of liquid consumption.

  20 brake control device, 23 wheel cylinder, 27 master cylinder unit, 32 master cylinder, 33 regulator, 34 reservoir, 60 separation valve, 65 regulator cut valve, 66 pressure-increasing linear control valve, 67 pressure-reducing linear control valve, 70 brake ECU, 73 control pressure sensor, 80 switching valve, 82 bypass path.

Claims (1)

A pump for accumulating hydraulic fluid in the accumulator;
A first supply path for supplying hydraulic fluid accumulated in the accumulator to the wheel cylinder;
A second supply path for supplying hydraulic fluid delivered by the pump to the wheel cylinder;
A switching mechanism that switches between the first supply path and the second supply path so that hydraulic fluid is supplied to the wheel cylinder by one of the first supply path and the second supply path;
It is determined whether or not the accumulator pressure accumulation satisfies a standard, and if the standard is satisfied, the first supply path is selected, and if the standard is less than the standard, the switching mechanism is selected to select the second supply path. And a control unit for controlling the brake control device.

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