JP2011131706A - Brake control device and operation determining method of solenoid valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine an operation state of a solenoid valve arranged in a working fluid passage of a brake control device. <P>SOLUTION: This brake control device imparts braking force by supplying a working fluid to a wheel cylinder arranged in response to respective wheels of a vehicle. A flow passage of the working fluid to the wheel cylinder is provided with the solenoid valve having a solenoid and a plunger operating by an impression of an electric current on the solenoid. An electric current command part 106 supplies a starting current for operating the plunger to the solenoid from a power source. An electric current measuring part 102 measures an electric current value flowing in the solenoid. A valve operation determining part 104 determines that the plunger is operated when the electric current value measured by the electric current measuring part 102 reduces by a predetermined value or more after starting supply of the electric current to the solenoid. When determining that the plunger is operated, the electric current command part 106 supplies a holding current lower in the electric current value than the starting current to the solenoid. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a brake control device for a vehicle, and more particularly to control of an electromagnetic valve disposed in the brake control device.

  2. Description of the Related Art In recent years, many electronically controlled brake systems that control the braking force of each wheel so as to give an optimal braking force to the vehicle according to the traveling state of the vehicle have been adopted as a braking device in the vehicle. Such an electronically controlled brake system includes a plurality of electromagnetic valves in the flow path of the working fluid.

  The solenoid valve includes a solenoid, and can switch between an open state and a closed state of the valve by controlling a current supplied to the solenoid. The solenoid valve requires a starting current having a large current value at the time of starting, but once driven, the driving state can be maintained by supplying a holding current having a current value smaller than the starting current.

  Patent Document 1 discloses a brake control device that switches to a holding current having a current value lower than the starting current in a holding state after supplying a starting current to the solenoid valve.

JP 2007-230432 A

  In the technique described in Patent Document 1, the starting current at which the solenoid valve starts operating is learned, and the operation of the solenoid valve is estimated based on the energization time of the starting current to the solenoid. However, when such an estimation method is used, since the actual completion of the operation of the solenoid valve cannot be observed directly, there is a possibility that the starting current continues to flow even after the operation is completed. The power consumption of the solenoid valve increases as the starting current flows for an extra time.

  In an electronically controlled brake system mounted on a hybrid vehicle or the like, a plurality of solenoid valves are used for a brake actuator, and it is necessary to drive the plurality of solenoid valves each time a brake operation is performed by a driver. When the power consumption of each solenoid valve increases, a power supply apparatus that supplies power to a plurality of solenoid valves also needs to have a large capacity. In addition, even in a solenoid that occupies a large proportion of the volume of the electromagnetic valve, it is necessary to use a large-sized one when power consumption increases, and the problem of heat generation of the electromagnetic valve also arises. These are major issues in reducing the size and weight of electronically controlled brake systems.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique capable of early and surely determining the operation of an electromagnetic valve disposed in a flow path of a working fluid of a brake control device. is there.

  An aspect of the present invention is a brake control device that supplies a working fluid to a wheel cylinder provided corresponding to each wheel of a vehicle to apply a braking force. This device is provided in a flow path of a working fluid to a wheel cylinder, and includes a solenoid valve having a solenoid and a plunger that operates by applying a current to the solenoid, and an activation current for operating the plunger from a power source. A current command unit to be supplied to the solenoid, a measurement unit for measuring a current value flowing through the solenoid, and a current value measured by the measurement unit has decreased by a predetermined value or more after starting to supply current to the solenoid And an operation determination unit that determines that the plunger is operated.

  In the solenoid valve, the plunger is actuated by supplying a starting current to the solenoid, and when the plunger enters the solenoid, the inductance of the solenoid changes. Therefore, the value of the current flowing through the solenoid temporarily decreases. According to this aspect, the operation of the plunger can be confirmed without using an additional sensor by detecting the decrease in the current value.

  When the operation determining unit determines that the plunger has been operated, the current command unit may supply a holding current having a current value lower than the starting current to the solenoid. According to this, since it is switched from the starting current to the holding current immediately after confirming the completion of the operation of the plunger, the current consumption in the solenoid is reduced and the power can be saved.

  A power supply monitoring unit for determining whether the power supply voltage is equal to or higher than a predetermined threshold value, and when the power supply voltage falls below the threshold value, instead of determining the operation of the plunger by the operation determination unit, an activation current for the solenoid An energization time measuring unit that determines whether or not the plunger is operated based on the energization time. When the power supply voltage fluctuates, it is difficult to determine a decrease in the solenoid current value due to a decrease in the power supply voltage and a decrease in the solenoid current value due to an increase in the inductance component. Therefore, when the power supply voltage is lowered, it is possible to prevent erroneous determination of the operation state by estimating the plunger operation based on the energization time of the starting current.

  Another aspect of the present invention is a method for determining the operation of a solenoid valve. According to this method, in a brake control device that supplies a working fluid to a wheel cylinder provided corresponding to each wheel of a vehicle to apply a braking force, an electromagnetic having a solenoid and a plunger that operates by applying a current to the solenoid. When a valve is provided in the flow path of the working fluid to the wheel cylinder, a starting current for operating the plunger is supplied from a power source to the solenoid, a current value flowing through the solenoid is measured, and the solenoid is supplied to the solenoid. After the start of supply of the current, when the measured current value decreases by a predetermined value or more, it is determined that the plunger is operated.

  ADVANTAGE OF THE INVENTION According to this invention, the operation | movement determination of the solenoid valve arrange | positioned in the flow path of the working fluid of a brake control apparatus can be performed early and reliably.

It is a distribution diagram showing a brake control device concerning one embodiment of the present invention. It is a figure which shows the solenoid valve drive circuit of the brake control apparatus which concerns on one Embodiment. It is a timing chart of the instruction | command from brake ECU, the action | operation of the plunger of a solenoid valve, the inductance of a solenoid, and the electric current which flows through a solenoid. It is a functional block diagram of the part which participates in the operation determination of the solenoid valve concerning one embodiment among brake ECUs. It is a flowchart which shows the solenoid valve action | operation determination by one Embodiment. (A), (b) is a figure which compares the operation determination method of the conventional solenoid valve, and the operation determination method of the solenoid valve by this embodiment. It is a flowchart which shows one modification of electromagnetic valve action | operation determination.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  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.

  As shown in FIG. 1, the brake control device 20 includes disc brake units 21FR, 21FL, 21RR and 21RL as a braking force application mechanism provided for each wheel (not shown), a master cylinder unit 10, A hydraulic pressure source 30 and a hydraulic actuator 40 are included.

  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 10 as a manual hydraulic pressure source sends brake 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. The power hydraulic pressure source 30 can send brake fluid as working fluid pressurized by supplying power to the disc brake units 21FR to 21RL independently of 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 10 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. In the present embodiment, the wheel cylinder pressure control system is configured including the power hydraulic pressure source 30 and the hydraulic actuator 40.

  Each of the disc brake units 21FR to 21RL, the master cylinder unit 10, 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.

  The master cylinder unit 10 is a master cylinder with a hydraulic booster in this embodiment, and includes a hydraulic booster 31, a master cylinder 32, a regulator 33, and a reservoir 34. 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 power hydraulic pressure source 30 includes an accumulator 35 and a pump 36. The accumulator 35 converts the pressure energy of the brake fluid boosted by the pump 36 into the pressure energy of an enclosed gas such as nitrogen, for example, about 14 to 22 MPa and stores it. The pump 36 has a motor 36 a as a drive source, and its suction port is connected to the reservoir 34, while its discharge port is connected to the accumulator 35. The accumulator 35 is also connected to a relief valve 35 a provided in the master cylinder unit 10. 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 includes an actuator block in which a plurality of flow paths are formed, and a plurality of electromagnetic 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 solenoid 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 both are normally closed solenoid valves that are 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 10 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 side 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 side wheel cylinder via the individual flow paths 43 and 44. Connected to 23RR and 23RL.

  The separation valve 60 is a normally closed solenoid valve that has a solenoid and a spring that are controlled to be turned on and off, and 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 has a solenoid and a spring that are ON / OFF controlled, and is a normally open solenoid valve that is opened when the solenoid is in a non-energized state. 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 the solenoid is energized and the master cut valve 64 is closed, the flow of brake fluid in the master channel 61 is blocked.

  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 is a normally closed solenoid valve that has a solenoid and a spring that are ON / OFF controlled and is closed when the solenoid is in a non-energized state. 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 according 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, one having a multi-stage spring characteristic is preferably employed in order to improve the feeling of brake operation by the driver, and the stroke simulator 69 of the present embodiment has a multi-stage spring characteristic.

  The regulator flow path 62 has a regulator cut valve 65 in the middle. The regulator cut valve 65 also has a solenoid and a spring that are ON / OFF controlled, and is a normally open solenoid valve that is opened when the solenoid is in a non-energized state. 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 present embodiment, as described above, the master cylinder 32 of the master cylinder unit 10 communicates with the wheel cylinders 23FR and 23FL on the front wheel side by the first system that includes the following elements. The first system includes a master pipe 37, a master channel 61, a master cut valve 64, a first channel 45a of the main channel 45, individual channels 41 and 42, and ABS holding valves 51 and 52. The hydraulic booster 31 and the regulator 33 of the master cylinder unit 10 are communicated with the wheel cylinders 23RR and 23RL on the rear wheel side by a second system that includes the following elements. The second system includes a regulator pipe 38, a regulator channel 62, a regulator cut valve 65, a second channel 45b of the main channel 45, individual channels 43 and 44, and ABS holding valves 53 and 54.

  Therefore, the hydraulic pressure in the master cylinder unit 10 pressurized according to the brake operation amount by the driver is transmitted to the wheel cylinders 23FR and 23FL on the front wheel side through the first system. The hydraulic pressure in the master cylinder unit 10 is transmitted to the wheel cylinders 23RR and 23RL on the rear wheel side through the second system. Thereby, the braking force according to the amount of brake operation of the driver can be generated in each wheel cylinder 23.

  In addition to the master channel 61 and the regulator channel 62, an accumulator channel 63 is also formed in the hydraulic actuator. 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-reducing linear control valve 67 each have a linear solenoid and a spring, and both are normally closed solenoid 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.

  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 and 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.

  In the present embodiment, a pressure control mechanism is configured including the power hydraulic pressure source 30, the pressure-increasing linear control valve 66, and the pressure-decreasing linear control valve 67. The hydraulic pressure in the wheel cylinder 23 is controlled by operating the pressure control mechanism. Since the second flow path 45b of the main flow path 45 is communicated between the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67, the pressure control mechanism can operate the wheel on the rear wheel side regardless of whether the separation valve 60 is opened or closed. The hydraulic pressure of the cylinders 23RR and 23RL can be controlled. If the separation valve 60 is in the open state, the hydraulic pressures of all the wheel cylinders 23 can be controlled by operating the pressure control mechanism.

  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 control means 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 of the power hydraulic pressure source 30 and the hydraulic pressure Brake control can be executed by controlling the electromagnetic valves 51 to 54, 56 to 59, 60, and 64 to 68 constituting the actuator 40.

  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.

  When the brake pedal 24 is depressed by the driver, the brake ECU 70 calculates the target deceleration of the vehicle from the pedal stroke and the master cylinder pressure. Then, the brake ECU 70 calculates the target hydraulic pressure of the wheel cylinder 23 based on the calculated target deceleration, and supplies it to the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67 so that the wheel cylinder pressure becomes the target hydraulic pressure. Determine the current value. As a result, in the brake control device 20, the brake fluid is supplied from the power hydraulic pressure source 30 via the pressure-increasing linear control valve 66 to each wheel cylinder 23 and braking force is applied to each wheel. At this time, the brake ECU 70 opens the separation valve 60 so that the brake fluid from the power hydraulic pressure source 30 is supplied to the front wheels, while the master cut valve 64 and the regulator cut valve 65 are closed. The brake fluid sent from the master cylinder 32 and the regulator 33 is prevented from being supplied to the main flow path 45.

  FIG. 2 shows an electromagnetic valve drive circuit of the brake control device 20 according to the present embodiment. The DC power supply device (battery) 96 is a power supply device for driving a plurality of electromagnetic valves of the brake control device 20. The DC power supply device 96 supplies current to a plurality of solenoid valve drive circuits via electronic components such as a filter 92 and a solenoid relay 94. The current that has passed through the filter 92 and from which the noise component has been removed flows to a plurality of solenoid valve drive circuits connected in parallel via the power line 99. In FIG. 2, one electromagnetic valve driving circuit 88 is shown, and the other electromagnetic valve driving circuits are not shown.

  The solenoid valve drive circuit 88 controls the current supplied to the solenoid 90 of the solenoid valve by a control signal from the brake ECU 70. The solenoid valve drive circuit 88 includes a P-channel type FET 80, an N-channel type FET 82, a flywheel diode 84, and a current detection resistor 86.

  The source terminal of the FET 80 is connected to the power supply line 99. The gate terminal of the FET 80 is connected to the brake ECU 70 via the control signal line 97. A solenoid 90 is connected between the drain terminal of the FET 80 and the drain terminal of the FET 82. The cathode terminal of the flywheel diode 84 is connected to the drain terminal of the FET 80, and the anode terminal of the flywheel diode 84 is grounded. The gate terminal of the FET 82 is connected to the brake ECU 70 via the control signal line 98. One terminal of the current detection resistor 86 is connected to the source terminal of the FET 82, and the other terminal of the current detection resistor 86 is grounded. The source terminal of the FET 82 is connected to the brake ECU 70 via the current monitor line 95.

  When the solenoid valve operates, the air gap disappears and the magnetic permeability increases, so that the current required to hold the plunger after the operation becomes small. In other words, the solenoid valve needs a starting current having a large current value at the time of starting, but once driven, it maintains a driving state by supplying a holding current having a current value smaller than the starting current. Can do. By changing the current supplied according to the state of the solenoid valve, current consumption and heat generation can be reduced. In the present embodiment, the brake ECU 70 can control the current I supplied to the solenoid 90 of the solenoid valve by changing the duty ratio of the control signal supplied to the gate terminal of the FET 80 by PWM duty control.

  In the brake control device 20, the brake ECU 70 is configured to start supplying current to the plurality of electromagnetic valves at different timings when a brake operation is performed. The brake ECU 70 controls each of the plurality of solenoid valves to switch to a holding current having a current value lower than the startup current after supplying a startup current for starting the solenoid valve. After the current to be supplied is switched from the starting current to the holding current, the starting current is started to be supplied to the next solenoid valve.

  In general, the electromagnetic valve includes a solenoid 90 and a plunger (not shown) arranged to be movable in the longitudinal direction inside the solenoid. When a current greater than the starting current is applied to the solenoid, the plunger is attracted into the solenoid by the magnetic force of the solenoid. The electromagnetic valves shown in FIG. 1 are all two-position valves, and are configured to open and close the flow path in which the valves are arranged by moving the plunger. Since the configuration and operation of such a solenoid valve are well known, further detailed description is omitted in this specification.

  There are two types of solenoid valves, normally open and normally closed, which must be opened or closed by the urging force applied to the plunger when no current is applied. This is different from the drive state of the solenoid valve. In the following description, regardless of whether the solenoid valve is normally open or normally closed, it is said that the solenoid valve or plunger “activates” when a current is applied to the solenoid and the plunger moves completely. When no current is applied to the solenoid and the plunger is outside the solenoid, the solenoid valve or plunger is said to be “inactive”. That is, if it is a normally open valve, it is closed when the electromagnetic valve is operated, and if it is a normally closed valve, it is opened when the electromagnetic valve is operated.

FIG. 3 is a timing chart of (a) a command from the brake ECU, (b) operation of the plunger, (c) inductance of the solenoid, and (d) current flowing through the solenoid. As illustrated, the command for applying a starting current from the brake ECU70 is made at time t _1. At this time, the plunger does not immediately actuate at t ₁ , but enters the actuated state at a time t ₃ , for example, after a time. In the prior art such as the above-mentioned Patent Document 1, in order to determine whether or not the plunger has actually actuated in accordance with an instruction from the ECU, the energization time of the starting current flowing through the solenoid is measured. On the other hand, the inventor of the present application has focused on the fact that the current flowing through the solenoid once decreases before reaching the starting current value from the start of current application. It has been experimentally confirmed that this decrease in current is a phenomenon that occurs because the magnetic flux increases as the plunger moves into the solenoid and the inductance of the solenoid increases.

  Therefore, in this embodiment, after the electromagnetic valve ON command by the brake ECU 70, the operation timing of the solenoid valve plunger is detected by monitoring the decrease in the current flowing through the solenoid.

  FIG. 4 is a functional block diagram of a portion of the brake ECU 70 that is involved in the operation determination of the solenoid valve according to the present embodiment. Each block shown here can be realized in hardware by an element and a mechanical device including a computer CPU and memory, and in software by a computer program or the like. It is drawn as a functional block to be realized. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

  The current measuring unit 102 measures the value of current flowing through the solenoid 90. The current command unit 106 supplies a starting current for operating the plunger from the power source to the solenoid 90. Here, the “starting current” is a current (for example, 1.5 A) required at the start of solenoid operation.

  The valve operation determination unit 104 reduces the current value measured by the current measurement unit 102 by a predetermined value α or more in a transient state after starting to apply current to the solenoid 90, that is, until reaching the starting current. It is determined that the plunger has operated. The predetermined value α may be defined as, for example, what percentage of the starting current, or how many amperes, based on experiments. Or you may set to the electric current fall amount estimated from the increment of the inductance when a plunger approachs in a solenoid.

  When it is determined by the valve operation determination unit 104 that the plunger has been operated, the current command unit 106 supplies a holding current having a current value lower than the starting current. The holding current is a current (for example, 0.8 A) necessary for holding the solenoid (when the solenoid is continuously turned on).

  The power supply monitoring unit 108 determines whether the voltage of the DC power supply device 96 (hereinafter referred to as “power supply voltage”) is equal to or higher than a predetermined threshold value. This threshold value is set to a voltage at which the DC power supply device can exhibit performance as specified, for example.

  When the power supply voltage falls below the threshold value, the energization time measurement unit 110 determines the operation of the plunger based on the energization time of the activation current to the solenoid 90 instead of the plunger operation determination by the valve operation determination unit 104. When it is determined that the plunger is operated, the current command unit 106 supplies a holding current having a current value lower than the starting current.

  FIG. 5 is a flowchart showing electromagnetic valve actuation determination according to the present embodiment. When there is a command to turn on the solenoid valve from the brake ECU 70 in response to a brake operation by the driver, the current command unit starts supplying a starting current to the solenoid (S10). The current measuring unit 102 measures the current value flowing through the solenoid 90 (S12). The valve operation determination unit 104 determines whether the PWM duty control of the starting current is on, the current is in a transient state, and whether the measured current value has decreased by a predetermined value or more (S14). When all the determinations are affirmative (Y in S14), the valve operation determination unit 104 determines that the solenoid valve has been correctly operated and the plunger has moved (S16). In response to this determination, the current command unit 106 switches the current value supplied to the solenoid 90 from the starting current value to the holding current value (S18).

If any of the conditions is negative in S14 (N in S14), the valve operation determination unit 104 determines that the plunger has not yet moved (S20), and the current measurement unit 102 continues to flow through the solenoid 90. The current value is measured (S12).
Note that it is not necessary to determine all three conditions in S <b> 14, and at least a decrease in the current value measured by the current measuring unit 102 may be determined.

FIG. 6 is a diagram comparing a conventional electromagnetic valve operation determination method and the electromagnetic valve operation determination method according to the present embodiment.
FIG. 6A is a time chart simply showing the command of the brake ECU 70 and the current flowing through the solenoid 90 when the operation determination of the conventional solenoid valve is performed. As shown in the figure, in the conventional method, when the starting current is energized for a predetermined time t, it is determined that the plunger of the solenoid valve is operated, and the current value supplied to the solenoid is switched from the starting current to the holding current. Since it is not known exactly when the plunger completes the movement, an energizing time that can surely move is secured as t.

  On the other hand, FIG. 6B is a time chart that simply shows the command of the brake ECU 70, the operating state of the electromagnetic valve, and the current flowing through the solenoid 90 when the operation determination of the electromagnetic valve according to the present embodiment is made. is there. As shown in the drawing, in this embodiment, since the operation of the plunger is determined based on the detection of the decrease in the starting current, the current command unit 106 can switch from the starting current to the holding current immediately after the plunger is operated. As a result, power consumption in the solenoid can be reduced, and therefore heat generation from the solenoid valve is also suppressed.

  As described above, in the brake control device 20 according to the present embodiment, the plunger is operated by supplying the starting current to the solenoid, and the solenoid inductance changes when the plunger enters the solenoid, so that the solenoid flows. The operation of the plunger is confirmed using the phenomenon that the current value decreases once. Therefore, since the operation of the plunger can be reliably determined without using an additional sensor, the energization time of the starting current to the solenoid can be shortened to suppress power consumption and heat generation. As a result, the volume of the solenoid valve can be reduced.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

  FIG. 7 is a flowchart showing a modification of the electromagnetic valve operation determination. When there is a command to turn on the solenoid valve from the brake ECU 70 in response to a brake operation by the driver, the current command unit starts supplying a starting current to the solenoid (S30). The current measuring unit 102 measures the current value flowing through the solenoid 90 (S32). The valve operation determination unit 104 determines whether the duty control of the starting current is on, whether the current is in a transient state, and whether the measured current value has decreased by a predetermined value or more (S34). When all the determinations are affirmative (Y in S34), the power supply monitoring unit 108 detects the battery voltage and determines whether or not the battery voltage has dropped below the lower limit value (S36). If the battery voltage has not decreased (N in S36), the valve operation determination unit 104 determines that the solenoid valve has operated correctly and the plunger has moved (S44). In response to this determination, the current command unit 106 switches the current value supplied to the solenoid 90 from the starting current value to the holding current value (S40).

  If the battery voltage is less than or equal to the lower limit (Y in S36), it is unclear whether the decrease in the current value determined in S34 is due to the solenoid inductance or the battery voltage, so the valve operation determination unit In addition to the operation determination by 104, the energization time measurement unit 110 determines whether or not the energization time of the starting current to the solenoid 90 is a predetermined time or more (S38). If the energization time is equal to or longer than the predetermined time (Y in S38), it is determined that the plunger has moved due to the operation of the solenoid valve. In response to this determination, the current command unit 106 determines the current value supplied to the solenoid 90 The starting current value is switched to the holding current value (S40). In S38, when the energization time is less than the predetermined time (N in S38), the process waits until the predetermined time elapses.

If any of the conditions is negative in S34 (N in S34), the valve operation determination unit 104 determines that the plunger has not yet moved (S42), and the current measurement unit 102 continues to flow through the solenoid 90. The current value is measured (S32).
Note that it is not necessary to determine all three conditions in S <b> 34, and at least a decrease in the current value measured by the current measuring unit 102 may be determined.

  In general, when the power supply voltage drops while energizing the starting continuous current, whether the solenoid current fluctuates due to the influence of the power supply voltage drop, or whether the current drops due to the solenoid inductance increase accompanying the movement of the plunger. Cannot be distinguished. Therefore, according to this modification, the operation of the solenoid valve is determined by the energization time of the starting current to the solenoid. Therefore, erroneous determination of the operation of the solenoid valve can be avoided.

  20 brake control device, 23 wheel cylinder, 24 brake pedal, 30 power hydraulic pressure source, 32 master cylinder, 45 main flow path, 60 separation valve, 61 master flow path, 64 master cut valve, 65 regulator cut valve, 66 pressure increase linear Control valve, 67 pressure-reducing linear control valve, 70 brake ECU, 102 current measurement unit, 104 valve operation determination unit, 106 current command unit, 108 power supply monitoring unit, 110 energization time measurement unit

Claims (5)

In a brake control device for supplying a working fluid to a wheel cylinder provided corresponding to each wheel of a vehicle and applying a braking force,
An electromagnetic valve provided in a flow path of the working fluid to the wheel cylinder, and having a solenoid and a plunger that operates by applying an electric current to the solenoid;
A current command unit for supplying a starting current for operating the plunger from a power source to the solenoid;
A measurement unit for measuring a current value flowing through the solenoid;
An operation determination unit that determines that the plunger has been activated when the current value measured by the measurement unit has decreased by a predetermined value or more after the start of supply of current to the solenoid;
A brake control device comprising:   The current command unit supplies a holding current having a current value lower than the starting current to the solenoid when the operation determining unit determines that the plunger is operated. Brake control device. A power supply monitoring unit for determining whether the power supply voltage is equal to or higher than a predetermined threshold;
When the power supply voltage falls below a threshold value, an energization time measuring unit that determines whether or not the plunger has operated based on the energization time of the activation current to the solenoid instead of the operation determination of the plunger by the operation determining unit When,
The brake control device according to claim 2, further comprising: In a brake control device that supplies a working fluid to a wheel cylinder provided corresponding to each wheel of a vehicle to apply a braking force, an electromagnetic valve having a solenoid and a plunger that operates by applying a current to the solenoid is the wheel. When provided in the working fluid flow path to the cylinder,
Supplying a starting current for operating the plunger from a power source to the solenoid;
Measure the current value flowing through the solenoid,
A method for determining the operation of an electromagnetic valve, comprising: determining that the plunger has been operated when a measured current value has decreased by a predetermined value or more after starting the supply of current to the solenoid.   5. The method for determining the operation of an electromagnetic valve according to claim 4, wherein when it is determined that the plunger is operated, a holding current having a current value lower than the starting current is supplied to the solenoid.

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