JP2010095026A - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save electric power and to reduce the size, in a brake control device including an actuator and its control device such as a solenoid valve for hydraulic control. <P>SOLUTION: In this brake control device of a certain mode, in current-carrying control to a liner solenoid for opening-closing an opening-closing valve, a control current is controlled so as to reduce stepwise to a holding current from a starting current. When supplying the starting current, an initial current-carrying period Δt0 is secured regardless of the completion of a temperature correction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a brake control for controlling a braking force applied to a vehicle wheel.

  2. Description of the Related Art Conventionally, there is known a brake control device that generates a hydraulic pressure in a hydraulic circuit according to an operation of a brake pedal, supplies the hydraulic pressure to a wheel cylinder, and applies a braking force to the wheel. The hydraulic circuit is provided with a plurality of solenoid-operated solenoid valves. The hydraulic pressure is controlled by opening and closing each solenoid valve and adjusting the amount of hydraulic fluid supplied to and discharged from the wheel cylinders. A braking force is applied.

Among such solenoid valves, from the viewpoint of improving controllability and power saving, there is one that constantly applies a holding current lower than this after the start current is applied and maintains its drive state ( For example, see Patent Document 1). For example, a normally closed electromagnetic valve provided in a hydraulic circuit is opened by applying a starting current when the vehicle is driven, and then a predetermined holding current is supplied to maintain a predetermined valve opening state. Once such an electromagnetic valve is opened, the open state is maintained even with a smaller current value due to the hysteresis of the valve opening characteristic. By maintaining the valve open state in this way, the required hydraulic pressure can be supplied immediately when the brake pedal is depressed, and the control response can be kept good. On the other hand, by constantly supplying a holding current lower than the starting current, there is also an advantage that power consumption can be reduced compared to the case where the starting current is always held.
JP 2007-230432 A

  By the way, with the spread of so-called hybrid vehicles in recent years, the number of vehicle-mounted devices is also increasing, and there is an increasing demand for weight reduction and miniaturization of individual devices. For this reason, in order to realize the downsizing of the brake control device, for example, the device is integrated with an electronic control device (hereinafter referred to as “ECU”) that controls the actuator. .

  However, if the parts are densified by integrating the actuator and the ECU in this way, the influence of heat generated by the individual parts becomes a problem. That is, when the above-described two-stage control using the starting current and the holding current is employed, it is necessary to realize accurate energization control to the solenoid while securing the respective necessary currents. However, when a temperature drift occurs due to heat generation of the electromagnetic coil, it is difficult to realize accurate energization control and thus highly accurate braking control.

  In order to further reduce the size of the actuator, it is essential to reduce the size of the solenoid valve, particularly the solenoid. For this purpose, it is necessary to realize control that keeps the current supplied to the solenoid to the minimum necessary, and in that case, highly accurate energization control is also required.

  Therefore, an object of the present invention is to realize power saving and downsizing of an actuator such as a solenoid valve for hydraulic pressure control and a brake control device including the control device.

  In order to solve the above problems, a brake control device according to an aspect of the present invention includes a hydraulic pressure source that stores hydraulic fluid, a wheel cylinder that receives hydraulic fluid supply and applies hydraulic braking force to the wheel, and hydraulic pressure A hydraulic circuit that connects the power source and the wheel cylinder, an on-off valve that is disposed in the hydraulic circuit and that can be opened and closed by electromagnetic drive by energizing the solenoid to switch the flow of hydraulic fluid in the hydraulic circuit; The current detection unit that detects the current value applied to the solenoid and the duty control of the current supplied to the solenoid are performed, the starting current necessary to start the opening / closing operation is applied to the on-off valve, and the detection information by the current detection unit Based on the above, when the activation current is applied for a preset period for determining completion of the opening / closing operation of the on-off valve, a holding current smaller than the activation current is applied to maintain the opening / closing operation. And a control unit for controlling to controlled so.

  Here, the “open / close valve” is one in which the valve portion is controlled to open and close in accordance with a current value supplied from the outside to switch the passage of the hydraulic fluid, and may be, for example, the above-described normally closed solenoid valve. . Alternatively, it may be a normally open solenoid valve that is in a valve open state when not energized and closes when energized. The “set period” is a period in which the on-off valve can be reliably started, that is, a normally closed type on-off valve can be guaranteed to open, and a normally open type on-off valve can be guaranteed to close. For example, it can be set in advance based on the energization operation characteristics of the on-off valve. For example, allowable power consumption may be set in advance from the viewpoint of power saving, and as the setting period, a time during which the power consumption at the time of activation can be suppressed to be equal to or less than the allowable power consumption may be set.

  According to this aspect, by monitoring the current value applied to the on-off valve, it is possible to prevent switching from the starting current to the holding current before starting the operation of the on-off valve. As a result, the opening / closing valve can be reliably opened or closed by the starting current, and the operating state can be reliably maintained by the holding current supplied thereafter. Further, not only switching to a holding current having a small current value but also switching to the holding current promptly by determining whether the opening / closing operation of the opening / closing valve is complete can further reduce power consumption. Furthermore, by keeping the starting current applied to the minimum necessary, heat generation of the solenoid can be suppressed, and the influence of temperature drift on the opening / closing control of the opening / closing valve can be suppressed. As a result, the stability and accuracy of braking control can be maintained even when such on-off valves are arranged at high density as actuators of the brake control device.

  One or a plurality of stages of transition currents may be set between the starting current and the holding current so that the current value decreases stepwise from the starting current to the holding current. Then, the control unit may sequentially switch the target current each time the switching condition set for the transition from the starting current to the holding current in each stage is satisfied. When the transition current is set in a plurality of stages, the transition current in each stage is set so as to be smaller than the starting current and larger than the holding current and become smaller as the holding current is approached. The “switching condition” may be set as an elapsed time since the transition to each stage. Alternatively, completion of temperature correction described later may be used as the condition.

  According to this aspect, since the target current is controlled so as to gradually decrease from the starting current to the holding current in a stepwise manner, it is possible to shift to the final holding current while suppressing undershoot with respect to the target current. And stability of control can be ensured.

  When the controller changes the energization state in a stepwise manner from the starting current to the holding current, the current value set in each step can be obtained even if the resistance value changes as the solenoid temperature decreases. A temperature correction process for correcting the amount of current supplied to the on-off valve according to the temperature change of the solenoid may be executed.

  In other words, the amount of heat generated by the solenoid varies depending on the magnitude of the energization current, and its resistance value varies. In this case, switching from the starting current to the holding current stepwise reduces the amount of heat generated by the solenoid, and thus its resistance, stepwise. Therefore, if the duty ratio is set ignoring such a temperature change of the solenoid, there is a possibility that the effect of so-called temperature drift on the control is increased. According to this aspect, since the amount of current supplied to the on-off valve is corrected according to the temperature change of the solenoid, the influence of such temperature drift can be excluded or suppressed.

  Specifically, the control unit defines the correspondence between the supply current value to be supplied to the solenoid and the duty ratio as the energization command value in accordance with a control map that defines the reference temperature of the solenoid and the temperature change of the solenoid. You may hold | maintain the correction coefficient map which defined the correction coefficient of the duty ratio. When the energization state is changed from the starting current to the holding current, the duty ratio is obtained by referring to the control map, and the energization control is executed by applying a correction coefficient corresponding to the temperature decrease of the solenoid to the duty ratio. Good.

  Moreover, you may provide the voltage detection part which detects the power supply voltage as a supply source of the electric current to an on-off valve. Then, when the control unit performs the energization control with a duty ratio equal to or higher than a predetermined value when the power supply voltage is equal to or higher than the predetermined minimum operating voltage when the starting current is applied to the on-off valve, the temperature correction process is completed. Switching to the holding current may be executed regardless of the presence or absence.

  That is, in order to suppress the influence of temperature drift when switching the target current, it is preferable to complete the above-described temperature correction. However, if the starting current is continuously supplied for longer than necessary, the durability of the on-off valve may be adversely affected by heat generation. On the other hand, if the duty ratio can be increased in a state where the power supply voltage is equal to or higher than the minimum operating voltage, it is possible to secure the minimum starting current and ensure the start of the on-off valve. Therefore, especially when the power supply voltage is relatively low, the protection to the on-off valve is exceptionally switched to the holding current.

  According to the present invention, it is possible to realize power saving and downsizing of an actuator such as a solenoid valve for hydraulic pressure control and a brake control device including the control device.

The best mode for carrying out the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 is a system diagram showing a brake control device 20 according to the first embodiment of the present invention.
The brake control device 20 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 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.

  The brake control device 20 includes a disc brake unit 21FR, 21FL, 21RR and 21RL provided for each wheel, a master cylinder unit 27, a power hydraulic pressure source 30, a hydraulic actuator 40, and a fluid connecting them. Pressure circuit.

  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 a manual hydraulic pressure source sends brake fluid as hydraulic fluid pressurized according to the amount of operation by the driver of the brake pedal 24 as a brake operation member to the disc brake units 21FR to 21RL. To do. The power hydraulic pressure source 30 can send the brake 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. 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.

  The disc brake units 21FR to 21RL include 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 this 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, for example, about 14 to 22 MPa as pressure energy of an enclosed gas such as nitrogen and stores the pressure energy. 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 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. 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 is configured by incorporating a plurality of electromagnetic control valves into an actuator block in which a plurality of flow paths are formed. 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. In the following description, the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are sometimes collectively referred to simply as “linear control valves”.

  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. If the pressure-increasing linear control valve 66 and the like are made common to each wheel cylinder 23 in this way, 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 outlets 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.

  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 disposed in a terminal box assembled to the actuator block, is provided integrally with the hydraulic actuator 40, and operates upon receiving power supply from the battery 75. The brake ECU 70 is configured mainly with a microcomputer including a CPU, and includes a ROM for storing various programs, a RAM for temporarily storing 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 of the power hydraulic pressure source 30 and the hydraulic pressure The electromagnetic control valves 51 to 54, 56 to 59, 60, and 64 to 68 constituting the 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 by a predetermined amount.

  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 by a predetermined amount. 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 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 braking force by regeneration is supplied to the brake control device 20 from the hybrid ECU. Then, the brake ECU 70 calculates a target wheel cylinder pressure that is a target hydraulic pressure of each of the wheel cylinders 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 by a feedback control law so that the wheel cylinder pressure becomes the target wheel cylinder pressure.

  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 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.

  Specifically, the brake ECU 70 determines the deviation between the target hydraulic pressure that is the target value of the upstream pressure of the ABS holding valves 51 to 54 (also referred to as “holding valve upstream pressure”) and the actual pressure that is the actual hydraulic pressure. Accordingly, one of a pressure increasing mode, a pressure reducing mode, and a holding mode is selected, and the holding valve upstream pressure is controlled. The brake ECU 70 controls the pressure upstream linear control valve 66 and the pressure reducing linear control valve 67 to control the holding valve upstream pressure. The brake ECU 70 selects the pressure increase mode when the deviation exceeds the pressure increase required threshold, and selects the pressure reduction mode when the deviation exceeds the pressure reduction required threshold, and the deviation satisfies both the pressure increase required threshold and the pressure reduction required threshold. If not, that is, if it is within the set range, the holding mode is selected. Here, the deviation is obtained, for example, by subtracting the actual hydraulic pressure from the target hydraulic pressure. For example, the measured value of the control pressure sensor 73 is used as the actual fluid pressure. As the target hydraulic pressure, the holding valve upstream pressure, that is, the target value of the hydraulic pressure in the main flow path 45 is used.

  In the present embodiment, when the pressure increasing mode is selected, the brake ECU 70 supplies a feedback current corresponding to the deviation to the pressure increasing linear control valve 66. When the pressure reduction mode is selected, the brake ECU 70 supplies a feedback current corresponding to the deviation to the pressure reduction linear control valve 67. When the holding mode is selected, the brake ECU 70 does not supply current to the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67. That is, in the pressure increasing mode, the wheel cylinder pressure is increased via the pressure increasing linear control valve 66, and in the pressure reducing mode, the wheel cylinder pressure is decreased via the pressure decreasing linear control valve 67. In the holding mode, the wheel cylinder pressure is held.

  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.

  Note that the brake control device 20 according to the present embodiment can 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. Further, when the required braking force is provided only by the hydraulic braking force, the master cylinder pressure or the regulator pressure may be introduced into the wheel cylinder as it is. For example, the regulator cut valve 65 and the separation valve 60 are opened, the master cut valve 64, the pressure-increasing linear control valve 66, and the pressure-reducing linear control valve 67 are closed, and braking force is applied to each wheel by the regulator pressure. May be. Since the power hydraulic pressure source 30 is connected to the regulator 33 as a high pressure side, the accumulated pressure in the power hydraulic pressure source 30 can be effectively used to generate a braking force. Further, the operating frequency of the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 can be reduced, and the service life thereof can be improved.

  In addition, when it is determined that there is an abnormality in the control response of the wheel cylinder pressure during the control by the wheel cylinder pressure control system, a fail-safe process for mechanically applying a braking force using a manual hydraulic pressure source is performed. Is called. At this time, the brake ECU 70 stops supplying the control current to all the electromagnetic control valves. As a result, the brake fluid supply path is separated into two systems, the master cylinder side and the regulator side. The master cylinder pressure is transmitted to the front wheel wheel cylinders 23FR and 23FL, and the regulator pressure is transmitted to the rear wheel wheel cylinders 23RR and 23RL.

  Thus, in the control of the wheel cylinder pressure, the linear control of the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67 and the opening / closing control of the ABS holding valves 51 to 54 and the ABS pressure reducing valves 56 to 59 are mainly performed. Depending on the braking state, opening / closing control of the separation valve 60, the master cut valve 64, the regulator cut valve 65, and the simulator cut valve 68 is appropriately executed. In particular, for the separation valve 60, the master cut valve 64, the regulator cut valve 65, and the simulator cut valve 68, since the open / closed state after the activation is maintained for a relatively long time, efficient energization control is performed from the viewpoint of power saving. Executed. Therefore, in this embodiment, the separation valve 60, the master cut valve 64, the regulator cut valve 65, and the simulator cut valve 68 are collectively referred to as “open / close valve 50” for convenience, and the energization control will be described in detail. As described above, the master cut valve 64 and the regulator cut valve 65 are normally open solenoid valves, whereas the separation valve 60 and the simulator cut valve 68 are normally closed solenoid valves. For this reason, the former on-off valve 50 operates from the valve-open state to the valve-closed state by the activation, and the latter on-off valve 50 operates from the valve-closed state to the valve-open state by the activation.

FIG. 2 is a schematic diagram showing an on-off valve drive circuit in the brake control device 20.
The brake ECU 70 is configured around the microcomputer (hereinafter referred to as “microcomputer”) 80 as described above, and includes a CPU, a ROM, a RAM, an input / output port, and the like. The microcomputer 80 calculates a current value (target current value) to be supplied to the on-off valve 50 (more precisely, the linear solenoid S of the on-off valve 50) according to the braking state, and outputs the duty ratio as a feedforward term. Then, as a result of energization control with the duty ratio, the current value (actual current) actually flowing to the on-off valve 50 is fed back, and feedback control is executed according to the deviation between the target current and the actual current. In the present embodiment, in particular, a device is devised to save power while maintaining a target value set as a feedforward term with high accuracy. Details thereof will be described later.

  The brake ECU 70 further includes a PWM signal output circuit 82 for outputting a PWM signal for duty control of the on-off valve 50, a drive circuit 84 for turning on / off the on-off valve 50 in accordance with the PWM signal, an analog signal An A / D converter 85 for converting the signal into a digital signal is provided.

  The drive circuit 84 includes a P-channel MOSFET (hereinafter simply referred to as “FET”) 86 and an N-channel MOSFET (hereinafter simply referred to as “FET”) 88 arranged in series. The positive terminal of the battery 75 mounted on the vehicle is connected to the drain of the FET 86 via the BS relay 90. The gate of the FET 86 is connected to the PWM signal output circuit 82, and the source is connected to one end of the electromagnetic coil of the linear solenoid S. The other end of the electromagnetic coil is connected to the drain of the FET 88. The gate of the FET 88 is connected to the PWM signal output circuit 82, and the source is connected to the negative terminal of the battery 75 via the current detection resistor 89 and the ground line. The PWM signal from the PWM signal output circuit 82 is supplied to each gate of the FET 86 and the FET 88.

  In the above configuration, when the PWM signal from the PWM signal output circuit 82 is at a high level, the FET 86 and the FET 88 are turned on, and the energization path from the battery 75 to the linear solenoid S is conducted. Conversely, when the PWM signal is at a low level, the FET 86 and FET 88 are turned off, and the energization path to the linear solenoid S is interrupted. As described above, when both FETs of the drive circuit 84 are turned on / off according to the PWM signal output from the PWM signal output circuit 82, the current flowing through the linear solenoid S is duty-controlled. A voltage proportional to the current flowing through the linear solenoid S is generated at both ends of the current detection resistor 89. This voltage signal is input to the microcomputer 80 via the monitor line 92 and the A / D converter 85.

  The BS relay 90 is used for fail-safe, and cuts off the current supply to the on-off valve 50 when an abnormality of the linear solenoid S is detected. The lower FET 88 is also used for fail-safe. That is, even if the FET 86 fails while maintaining the on state, the energization path is interrupted by turning off the FET 88.

FIG. 3 is a block diagram schematically illustrating the function of the brake ECU 70.
The brake ECU 70 includes a target current calculation unit 100, a current-duty conversion unit 102, a temperature correction unit 104, a clamp 106, a pulse output unit 108, an A / D conversion unit 110, a digital filter 112, a switching unit 114, a PI control unit 116, An interrupt processing unit 118 and a target current monitoring unit 120 are provided.

  When a braking request is input to the brake ECU 70 based on the operation of the brake pedal 24, the target current calculation unit 100 calculates the required hydraulic braking force as described above and supplies it to the on-off valve 50 according to the braking state. The current value is calculated as the target current. This target current is input to the current-duty conversion unit 102. The current-duty conversion unit 102 includes a control map that defines a correspondence relationship between a target current that should be supplied to the linear solenoid S of the on-off valve 50 and a duty ratio that is set to obtain the target current. The current-duty conversion unit 102 refers to this control map using the calculated target current, and converts the target current into a duty ratio. On the other hand, the temperature correction unit 104 holds a correction coefficient map that defines a correction coefficient KT of a duty ratio corresponding to a temperature change of the linear solenoid S, and the linear solenoid S with respect to the duty ratio obtained from this control map. Temperature correction is performed by applying a correction coefficient KT corresponding to the temperature change.

  FIG. 4 is a diagram showing an outline of a control map used for energization control to the on-off valve 50. FIG. 5A shows a control map in which the correspondence relationship between the supply current value to be supplied to the linear solenoid S and the duty ratio as the energization command value is defined with respect to the reference temperature of the linear solenoid S. On the other hand, FIG. 5B shows a correction coefficient map in which a correction coefficient for the duty ratio corresponding to the temperature change of the linear solenoid S is defined. In the figure, the horizontal axis represents the target current, and the vertical axis represents the duty ratio. FIG. 5 is an explanatory diagram illustrating a method of setting a duty factor correction coefficient in the temperature correction process. The figure shows the change in the control current and the duty ratio in order from the top. The horizontal axis of the figure represents the passage of time.

  As shown in FIG. 4A, in this control map, the relationship between the target current and the duty ratio when the temperature of the linear solenoid S is a predetermined reference temperature (normal temperature: 25 ° C. in this embodiment) is set. Has been. This control map is obtained by converting the correlation between the duty ratio and the actual current when the linear solenoid S is actually set to the reference temperature into data. As shown in the figure, when the target current is I, the duty ratio D0 may be set under the reference temperature.

  On the other hand, the temperature of the linear solenoid S changes depending on the external environment such as other heat generating components arranged in the vicinity of the on-off valve 50 and the energized state of itself. As a result, the resistance value changes due to the temperature change of the linear solenoid S, and the duty ratio to be set may be different even when controlling to the same current value. As shown in FIG. 4B, if the linear solenoid S is in a lower temperature state than the reference temperature, the duty ratio may be smaller than that in the reference temperature, and conversely, the linear solenoid S is in a higher temperature state than the reference temperature. If so, the duty ratio needs to be larger than that at the reference temperature. Therefore, in this embodiment, the duty ratio is corrected according to the temperature change of the linear solenoid S. Specifically, the temperature change is indirectly acquired by checking how much the actual current is deviated from the duty ratio as the command value with reference to the control map shown in FIG. In a modified example, the temperature of the linear solenoid S may be detected by temperature detection means such as a thermistor and corrected based on the temperature change.

  That is, in the present embodiment, in order to cause the supply current to the on-off valve 50 to accurately follow the target current with respect to the temperature change of the linear solenoid S, the temperature correction process is executed for the duty ratio as a control command. Specifically, for example, when the target current I is calculated in a low temperature state indicated by a two-dot chain line in the figure, the duty ratio is not D0 but KT · D0 (KT = D / D0). As described above, the current-duty conversion unit 102 and the temperature correction unit 104 perform feedforward control for converting the target current into a duty of an appropriate current to be supplied to the linear solenoid S.

  However, even if such temperature correction is performed, the actual current actually flowing through the linear solenoid S (solid line in the figure) converges to the corrected target current (dashed line in the figure) as shown in the upper part of FIG. Takes some time. For this reason, the brake ECU 70 enters a predetermined stable region indicating that the actual current has almost converged to the target current (following within 4 LSB, for example), and performs temperature correction when a predetermined determination reference time Δt1 (for example, 54 ms) has elapsed. Is completed, and the temperature correction completion flag set in a predetermined area on the RAM is turned on. Then, upon completion, the target current is shifted to the next stage.

  Returning to FIG. 3, the clamp 106 removes noise superimposed on the output signal from the current-duty converter 102. That is, when a signal outside the range of 0 to 100% is output as the duty ratio, this is cut as an error.

  The pulse output unit 108 drives the PWM signal output circuit 82, outputs PWM signals to the FET 86 and FET 88, executes duty control to turn them on / off, and supplies current to the linear solenoid S. That is, the pulse output unit 108 changes the current supplied to the linear solenoid S at the duty ratio input by the feedforward control performed by the current-duty conversion unit 102 and the temperature correction unit 104. Thereby, drive control of the on-off valve 50 is performed.

  The A / D converter 110 A / D converts the voltage signal applied to the linear solenoid S and outputs a digital signal. The digital filter 112 performs a filtering process on the digital signal output from the A / D conversion unit 110. In the present embodiment, a filtering method using a moving average method is employed. By this filtering process, noise components included in the digital signal are removed. A voltage is detected from the digital signal passing through the digital filter 112, and the current supplied to the linear solenoid S is calculated from the voltage value.

  The target current monitoring unit 120 monitors the target current value calculated by the target current calculation unit 100 and outputs it. The switching unit 114 compares the monitored current value, which is the current value of the actual current supplied to the linear solenoid S, with the target current value at predetermined time intervals, and the monitored current value fluctuates by more than the threshold current value from the target current value. Determine whether or not.

  The switching unit 114 inputs the digital signal output from the digital filter 112 to the PI control unit 116 when it is determined that the monitoring current value does not fluctuate by a threshold current value or more than the target current value. On the other hand, when the monitoring current value fluctuates by more than the threshold current value than the target current value due to, for example, a steep fluctuation in the monitoring current value when overshoot, undershoot, or the like occurs, the switching unit 114 detects the digital filter 112. The digital signal output from is input to the interrupt processing unit 118.

  When the monitored current value does not fluctuate more than the threshold current value than the target current value, the PI control unit 116 performs PI control, that is, proportional control (P) so that the processed digital signal input from the digital filter 112 approaches the target value. Control) and integral control (I control). The PI control unit 116 outputs the PI control result as a duty ratio correction value. The pulse output unit 108 supplies current to the linear solenoid S based on the corrected duty ratio.

  Thus, the brake ECU 70 controls the driving of the linear solenoid S by feedback control that detects the actual current of the linear solenoid S and controls the PI control unit to approach the target value. That is, when the monitored current value does not fluctuate more than the threshold current value than the target current value, the brake ECU 70 performs feedforward control by the current-duty conversion unit 102 and the temperature correction unit 104, and feedback by the PI control unit 116, etc. The drive of the linear solenoid S is controlled by both control.

  When the monitored current value fluctuates more than the threshold current value than the target current value, it is difficult for the feedback control by the PI control unit 116 to bring the current supplied to the linear solenoid S close to the target value. For this reason, the interrupt processing unit 118 performs an interrupt process that suppresses a change in the monitoring current value that fluctuates sharply. In this interrupt processing, feedback control based on the monitored current value of the linear solenoid S detected as in the PI control unit 116 is not performed. That is, when the monitored current value fluctuates by more than the threshold current value than the target current value, the brake ECU 70 performs linear solenoid by feedforward control by the current-duty conversion unit 102 and the temperature correction unit 104 and interruption processing by the interruption processing unit 118. The drive of S is controlled.

  The on-off valve 50 requires a starting current having a relatively large current value at the time of starting, but once it is driven, the starting state is maintained by supplying a holding current having a current value smaller than the starting current. can do. The current consumption can be saved by sufficiently and sufficiently suppressing the supply current according to the open / close state of the on-off valve 50. Further, the heat generation of the linear solenoid S can be reduced by reducing the supply current, and the influence of temperature drift in the opening / closing control of the opening / closing valve 50 can be suppressed. In this embodiment, the brake ECU 70 changes the duty ratio of the control signal supplied to the gates of the FET 86 and FET 88 by PWM control, and controls the current supplied to the linear solenoid S of the solenoid valve.

  FIG. 6 is a timing chart showing a method for controlling energization to the on-off valve 50. In the figure, the operation command from the upper stage to the on-off valve 50, the control current to the linear solenoid S, and the state of the temperature correction completion flag indicating completion of temperature correction are shown. The horizontal axis of the figure represents the passage of time.

  In the example shown in the drawing, since there is a start command to the on-off valve 50 at time t1 according to the braking state, the energization control state is shifted to the stage 1 and the start current is set as the target current. At this time, the above-described temperature correction process corresponding to the temperature change is executed at the same time. When this temperature correction is completed, the brake ECU 70 temporarily turns on the temperature correction completion flag set in a predetermined area on the RAM, and shifts the energization control state to the next stage.

  Since the temperature correction is completed at time t2, the stage is shifted to the stage 2, and the target current is switched to the first transition current that is slightly lower than the starting current. Similarly, the temperature correction process is performed when the control current is switched. Similarly, since the temperature correction for the first transition current is completed at time t3, the stage transitions to stage 3, and the target current is switched to the second transition current that is slightly lower than the first transition current. Furthermore, since the temperature correction for the second transition current is completed at time t4, the stage transitions to stage 4, and the target current is switched to a holding current lower than the second transition current. The holding current is set in advance with a current value necessary and sufficient to maintain the open / closed state after the opening / closing valve 50 is activated. And since there was an operation stop command of the on-off valve 50 at time t5 according to the braking state, energization of the control current to the on-off valve 50 is stopped. Thus, in the present embodiment, the target current is decreased stepwise after the start-up current is applied, and the target current is shifted to the holding current.

  In the present embodiment, an initial energization period Δt0 (for example, 12 ms) for determining completion of the opening / closing operation is set in advance in order to guarantee activation (opening / closing operation) of the opening / closing valve 50. The initial energization time Δt0 is set based on the energization operation characteristics of the on-off valve 50, and the minimum time required for the on-off valve 50 to be reliably opened or closed after the start-up current is energized. In the illustrated example, since the temperature correction is completed after the initial energization time Δt0 has elapsed, the temperature correction is completed and the process proceeds to the next stage. However, the temperature correction is completed before the initial energization time Δt0 has elapsed. In this case, after the initial energization time Δt0 has elapsed, the process proceeds to the next stage.

  FIG. 7 is a flowchart showing a flow of energization control processing of the on-off valve 50. Note that the processing in the figure is executed in the course of execution of the entire braking control process including the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67. Details of the entire braking control process are as follows. Since the outline has already been described, the description thereof will be omitted.

  When an energization control command for the on-off valve 50 is output based on the braking state (Y in S10), the brake ECU 70 starts supplying an activation current to the on-off valve 50 (more precisely, the linear solenoid S) (S12). At the same time, the temperature correction process described above is executed. When the temperature correction is completed (Y in S14), if the initial energization period Δt0 has elapsed from the start of supply of the starting current (Y in S16), the stage 2 is entered and the supply of the first transition current is started. (S18). At the same time, the temperature correction process described above is executed. When the temperature correction is completed (Y in S20), the process proceeds to the stage 3 to start supplying the second transition current (S22). At the same time, the temperature correction process described above is executed. When the temperature correction is completed (Y in S24), the process proceeds to the stage 4 to start supplying the holding current (S26). Then, when the energization state of the holding current is maintained and the energization stop command for the on-off valve 50 is output based on the braking state (Y in S28), the energization is stopped (S30).

  As described above, in the present embodiment, in the energization control to the linear solenoid S for opening and closing the on-off valve 50, the control current is controlled so as to decrease stepwise from the starting current to the holding current. Therefore, it is possible to shift to the holding current while suppressing undershoot with respect to the target current, and it is possible to ensure the stability of the control. In addition, a temperature change occurs in the linear solenoid S by reducing the control current in such a stepwise manner. However, since temperature correction corresponding to the temperature change is executed, the effect of temperature drift is effectively suppressed. Can do.

  In addition, since the initial energization period Δt is ensured regardless of whether or not the temperature correction is completed when the starting current is supplied, the on-off valve 50 can be reliably opened and closed. Since the passage of the initial energization period Δt and the completion of the temperature correction are set as the transition timing to the next stage, it is possible to quickly switch to a holding current having a small current value, and power saving can be achieved. Further, since the heat generation of the linear solenoid S can be suppressed, the stability and accuracy of the control can be maintained even if such an on-off valve 50 is arranged at a high density as the actuator of the brake control device 20.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. This embodiment is substantially the same as the first embodiment except that the energization control process for the on-off valve 50 is slightly different. For this reason, the description of the configuration and processing parts common to the first embodiment in this embodiment will be omitted as appropriate.

  FIG. 8 is a timing chart showing an energization control method for the on-off valve 50 according to the second embodiment. The figure shows the operation command from the upper stage to the on-off valve 50, the control current to the linear solenoid S, the power supply voltage, the duty ratio of the control current, and the state of the temperature correction completion flag. The horizontal axis of the figure represents the passage of time.

  In order to suppress the undershoot of the control at the time of switching the target current, it is preferable to complete the above-described temperature correction at each stage of the energization control as shown in the first embodiment. However, if the starting current is continuously supplied longer than necessary, the durability of the on-off valve 50 may be adversely affected by heat generation. On the other hand, if the power supply voltage is equal to or higher than the minimum operating voltage and the duty ratio is sufficiently large, a minimum starting current that can start the on-off valve 50 (referred to as “minimum starting current”) can be secured. With respect to the “minimum operating voltage”, a voltage value that ensures at least activation of the on-off valve 50 by securing the initial energization period Δt0 is set in advance through experiments or the like. And if the minimum starting current is ensured, the operating state of the on-off valve 50 can be held even if the current value is gradually reduced to the holding current.

  In this embodiment, paying attention to this point, control that prioritizes protection of the on-off valve 50 is executed while performing temperature correction. The power supply voltage is obtained from an input signal from a sensor (corresponding to a “voltage detection unit”) that detects a voltage value of the battery 75. The “minimum operating voltage” and the “duty ratio” are preset with combinations that can ensure the minimum starting current.

  In the example shown in the figure, since there is a start command to the on-off valve 50 at time t21 according to the braking state, the energization control state is shifted to the stage 1 and the start current is set as the target current. At this time, the above-described temperature correction process corresponding to the temperature change is started at the same time. However, even if the power supply voltage is relatively low and the predetermined energization period Δt2 elapses after the initial energization period Δt0, the actual current does not converge to the target current after temperature correction during the energization control of the starting current. Is not turned on. On the other hand, the power supply voltage is higher than the minimum operating voltage V0 (for example, 9.3 V), and the minimum starting current can be secured by setting the duty ratio to 90% or more (100% in the illustrated example). In the figure, a thin solid line represents the target current, and a thick solid line represents the actual current flowing through the linear solenoid S.

  Since the minimum starting current is ensured in this manner, the stage 2 is shifted to time t22, and the target current is switched to the first transition current (for example, duty ratio 80%) slightly lower than the starting current. Similarly, the temperature correction process is performed when the control current is switched. Since the temperature correction of the first transition current is completed at time t23, the process proceeds to stage 3 as it is, and the target current is switched to a second transition current (for example, a duty ratio of 60%) slightly lower than the first transition current. . Furthermore, since the temperature correction for the second transition current is completed at time t24, the stage 4 is entered, and the target current is switched to a holding current (for example, a duty ratio of 40%) lower than the second transition current. The holding current is set in advance with a current value necessary and sufficient to maintain the open / closed state after the opening / closing valve 50 is activated. And since there was an operation stop command of the on-off valve 50 at time t25 according to the braking state, the energization of the control current to the on-off valve 50 is stopped. Thus, in the present embodiment, the target current is decreased stepwise after the start-up current is applied, and the target current is shifted to the holding current.

FIG. 9 is a flowchart showing a flow of energization control processing of the on-off valve 50. In the figure, the same processing steps as those in FIG. 7 are denoted by the same step numbers.
In this embodiment, the brake ECU 70 determines whether or not the power supply voltage is equal to or higher than the minimum operating voltage V0 when the supply of the starting current is started (S12). When the minimum operating voltage V0 is secured and the energization control is performed with a duty ratio of a predetermined value or more (for example, 90% or more) (Y in S214), on the condition that the initial energization period Δt0 has elapsed ( The process proceeds to the next stage regardless of whether the temperature correction is completed (Y in S16) (S18). That is, the protection of the on-off valve 50 is prioritized by ensuring the on-off valve activation while keeping the start-up current from being supplied longer than necessary.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added to the embodiments based on the knowledge of those skilled in the art, and such modifications have been added. Embodiments may also be included within the scope of the present invention.

  In the above embodiment, as shown in FIG. 1, the brake ECU 70 is provided integrally with the hydraulic actuator 40, while the power hydraulic pressure source 30 and the like are provided separately from the hydraulic actuator 40 and connected via a pipe. An example is shown. In the modified example, the power hydraulic pressure source 30 and the like may be integrally assembled with the hydraulic actuator 40 to reduce the size of the entire brake control device.

  In the above-described embodiment, as the brake control device 20, the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67, which are linear control valves common to the wheel cylinders 23, are provided, and the upstream pressure of each wheel cylinder 23 is increased. An example having a system configuration to control is illustrated. In the modified example, a system configuration in which a pressure increasing valve and a pressure reducing valve for executing linear control individually for each wheel cylinder 23 may be employed. Even in that case, the same processing can be applied to the on-off valve.

1 is a system diagram showing a brake control device according to a first embodiment of the present invention. It is the schematic which shows the drive circuit of the on-off valve in a brake control apparatus. It is the block diagram which modeled the function of brake ECU. It is a figure which shows the outline | summary of the control map used for the electricity supply control to an on-off valve. It is explanatory drawing showing the method of setting the correction factor of the duty ratio in temperature correction processing. It is a timing chart showing the electricity supply control method to an on-off valve. It is a flowchart which shows the flow of the electricity supply control process of an on-off valve. It is a timing chart showing the electricity supply control method to the on-off valve concerning 2nd Embodiment. It is a flowchart which shows the flow of the electricity supply control process of an on-off valve.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Brake control apparatus, 23 Wheel cylinder, 27 Master cylinder unit, 30 Power hydraulic pressure source, 32 Master cylinder, 33 Regulator, 34 Reservoir, 35 Accumulator, 40 Hydraulic actuator, 50 On-off valve, 51 ABS holding valve, 56 ABS pressure reduction Valve, 60 separation valve, 64 master cut valve, 65 regulator cut valve, 66 pressure-increasing linear control valve, 67 pressure-decreasing linear control valve, 68 simulator cut valve, 69 stroke simulator, 70 brake ECU, 75 battery, 80 microcomputer, 82 PWM Signal output circuit, 84 drive circuit, 85 A / D converter, 89 current detection resistor, 90 BS relay, 92 monitor line, 100 target current calculation unit, 102 current-duty conversion Unit, 104 temperature correction unit, 106 clamp, 108 pulse output unit, 110 A / D conversion unit, 112 digital filter, 114 switching unit, 116 PI control unit, 118 interrupt processing unit, 120 target current monitoring unit.

Claims (5)

A hydraulic pressure source for storing hydraulic fluid;
A wheel cylinder that receives hydraulic fluid supply and applies hydraulic braking force to the wheel;
A hydraulic circuit connecting the hydraulic pressure source and the wheel cylinder;
An on-off valve arranged in the hydraulic circuit and capable of switching the flow of hydraulic fluid in the hydraulic circuit by opening and closing by electromagnetic drive by energizing a solenoid;
A current detector for detecting a current value applied to the on-off valve;
The duty control of the current supplied to the solenoid is executed, the starting current necessary for starting the opening / closing operation is applied to the opening / closing valve, and the starting current is applied based on the detection information by the current detection unit. A control unit that controls to apply a holding current smaller than the starting current in order to maintain the opening / closing operation when a preset setting period is continued to determine whether the opening / closing operation of the valve is completed When,
A brake control device comprising: One or a plurality of stages of transition currents are set between the starting current and the holding current so that the current value decreases stepwise from the starting current toward the holding current,
2. The brake control device according to claim 1, wherein the control unit sequentially switches the target current each time a switching condition set for transition from the starting current to the holding current is established. .   When the control unit changes the energization state stepwise from the starting current toward the holding current, even if the resistance value changes as the solenoid temperature decreases, the current value set in each step 3. The brake control device according to claim 1, wherein a temperature correction process is performed to correct the amount of current supplied to the on-off valve in accordance with a temperature change of the solenoid. The controller is
A control map defining a correspondence relationship between a supply current value to be supplied to the solenoid and a duty ratio as an energization command value with respect to a reference temperature of the solenoid, and a correction coefficient of the duty ratio according to a temperature change of the solenoid Keep the defined correction factor map,
When the energization state is changed stepwise from the starting current to the holding current, the duty ratio is obtained by referring to the control map, and the duty ratio is multiplied by a correction coefficient corresponding to the temperature change of the solenoid. The brake control device according to claim 3, wherein energization control is executed. A voltage detection unit for detecting a power supply voltage as a supply source of current to the on-off valve;
The controller corrects the temperature when the power supply voltage is equal to or higher than a predetermined minimum operating voltage when the start-up current is applied to the on-off valve, and energization control is performed with a duty ratio equal to or greater than a predetermined value. 5. The brake control device according to claim 3, wherein switching to the holding current is executed regardless of whether or not processing is completed.

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