JP2009012557A - Brake controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake controller capable of securing accurate braking force. <P>SOLUTION: The accumulator 50 of this brake controller 110 is accumulated since the gas enclosed in the accumulator is compressed by the brake fluid supplied from an oil pump 34. The accumulator 70 is installed nearer a hydraulic pressure circuit 100 than an accumulator 50 for a high-pressure pipe 30, and accumulated when the gas enclosed therein is compressed by the brake fluid supplied from the oil pump 34 thereinto. A check valve 72 controls the supply of the brake fluid from the accumulator 70 to the hydraulic circuit 100, and the supply of the brake fluid from the oil pump 34 to the accumulator 70. An ECU 200 controls the opening and closing of a check valve 52 and the check valve 72 to supply the brake fluid from the accumulated accumulator 70 to the hydraulic circuit 100. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  2. Description of the Related Art Conventionally, there has been known a brake control device that controls the braking force of a vehicle by generating hydraulic pressure in a hydraulic circuit according to the operating force of a brake pedal and supplying the hydraulic pressure in the hydraulic circuit to a wheel cylinder. It has been. Among such brake control devices, there is one that brakes the vehicle by supplying hydraulic pressure to the wheel cylinder from an accumulator which is a hydraulic pressure source different from the master cylinder pressure (for example, Patent Document 1, Patent Document). 2). In such an apparatus, the operation amount of the brake pedal by the driver is detected, and the brake fluid is supplied from the accumulator that is accumulated so as to obtain the wheel cylinder pressure corresponding to the operation amount, and the hydraulic pressure is controlled.

  Generally, the viscosity of the brake fluid used in the brake control device increases as the temperature decreases. Therefore, when the temperature is low, the viscosity of the brake fluid supplied from the accumulator is high, and a response delay may occur in braking. Therefore, in Patent Document 3, when the temperature of the brake fluid is equal to or lower than the set temperature, the pump is operated, and the brake fluid is circulated while being heated by an electric heater in the apparatus, thereby increasing the temperature of the brake fluid. A brake fluid pressure control device provided with a temperature raising device is disclosed.

However, even with the device disclosed in Patent Document 3, it is difficult to sufficiently heat the entire brake fluid immediately after starting the vehicle at a very low temperature, and in order to completely eliminate the response delay. It does n’t come. In particular, if the accumulator and the hydraulic circuit are arranged apart from each other, it takes longer for the brake fluid stored in the accumulator to reach the hydraulic circuit, which affects the response of braking. Become.
JP 2006-175960 A JP 2006-131033 A JP 2001-191911 A

  Therefore, it is conceivable to place the accumulator near the actuator. For example, when a brake control device is installed in the engine room, depending on the vehicle, the accumulator and the high pressure can be maintained near the actuator due to space constraints. Sometimes it is difficult to place the pump.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a brake control device capable of ensuring a highly accurate braking force.

  In order to solve the above problems, a brake control device according to an aspect of the present invention includes a pump driven by a motor, and a first pressure accumulated by compressing a sealed gas by a working fluid supplied from the pump. 1 accumulator, a hydraulic circuit for controlling the supply of the working fluid to the braking force applying means for applying a braking force to the wheel using the hydraulic pressure of the working fluid, the pump, the first accumulator, and the hydraulic pressure A fluid path communicating with a circuit; pressure detecting means for detecting a pressure of a working fluid in the fluid path; and a sealed gas provided closer to the hydraulic circuit than the first accumulator in the fluid path Is compressed by the working fluid supplied from the pump, and the working fluid is supplied from the first accumulator to the hydraulic circuit. A first control valve for controlling the supply of the working fluid from the pump to the first accumulator, the supply of the working fluid from the second accumulator to the hydraulic circuit, and the second accumulator from the pump A second control valve that controls the supply of the working fluid to the first control valve, and a control unit that controls the opening and closing of the first control valve and the second control valve. The control unit controls opening and closing of the first control valve and the second control valve so that a working fluid is supplied from the second accumulator that has accumulated pressure to the hydraulic circuit.

  According to this aspect, since the second accumulator is provided at a position closer to the hydraulic circuit than the first accumulator, the hydraulic pressure is compared with the case where the working fluid is supplied from the first accumulator to the hydraulic circuit. The response delay of the pressure fluctuation of the working fluid pressure in the circuit can be reduced, and a highly accurate braking force can be secured.

  The control unit can control opening and closing of the first control valve and the second control valve so that pressure accumulation in the second accumulator is started before the first accumulator. Thereby, since the pressure accumulation in the second accumulator is started before the first accumulator, the pressure accumulation in the second accumulator that can reduce the response delay of the pressure fluctuation of the working fluid pressure in the hydraulic pressure circuit is shortened. Can be done in time.

  The second accumulator may be configured such that the gas volume at the sealing pressure of the second accumulator is smaller than the gas volume at the sealing pressure of the first accumulator. Thereby, the pressure accumulation of the second accumulator can be performed in a shorter time. Here, the volume of the second accumulator is determined in consideration of the amount of working fluid required for several times of braking performed in the time until the first accumulator is fully functioning and the space to be arranged. To decide. For the first accumulator to function satisfactorily, for example, the state in which pressure is accumulated to the extent that the braking force applying means can generate a sufficient braking force via the hydraulic circuit, or the viscosity of the working fluid increases. The state in which the viscosity of the working fluid is moderately lowered by heat generated by the vehicle in such a low temperature environment. Considering such points, it is possible to reduce the size of the second accumulator by determining the gas volume at the sealed pressure of the second accumulator. For example, even in an engine room where space is limited. It can be placed near the hydraulic circuit.

  The sealing pressure of the second accumulator may be set higher than the sealing pressure of the first accumulator. As a result, the second accumulator requires a small amount of working fluid for accumulating pressure to such an extent that a sufficient braking force can be generated in the braking force applying means. Therefore, if the amount of the working fluid supplied from the pump per unit time is constant, the second accumulator is accumulated to a predetermined control pressure in a shorter time.

  You may further provide the temperature information detection means which detects the information correlated with the temperature of the said working fluid. When the temperature of the working fluid calculated based on the detected information is lower than a predetermined temperature, the control unit starts the pressure accumulation in the second accumulator before the first accumulator. The opening and closing of the first control valve and the second control valve may be controlled. Here, the predetermined temperature can be regarded as a threshold value at which the viscosity of the working fluid increases such that the response delay of braking exceeds the allowable range. Specifically, for example, 0 ° C. below freezing point may be set as the predetermined temperature, or the predetermined temperature may be determined in the range of −30 ° C. to −40 ° C. in a cryogenic environment where the viscosity of the working fluid is increased. Good. As a result, the second accumulator closer to the hydraulic circuit than the first accumulator is accumulated first in an environment where the response delay of braking exceeds the allowable range when the operation of only the first accumulator is lower than the predetermined temperature. By doing so, the brake control device becomes in a state where the response delay of the braking can be within the allowable range in a shorter time.

  When detecting that the ignition is turned on, the control unit drives the pump with the first control valve closed and the second control valve opened, and the supplied working fluid supplies the first control valve. After accumulating the second accumulator to a predetermined pressure, the second control valve may be closed and the first control valve may be opened to accumulate the first accumulator to a predetermined pressure. As a result, the second accumulator closer to the hydraulic circuit than the first accumulator can be accumulated first in conjunction with the ignition being turned on at the start when the vehicle is not warm.

  ADVANTAGE OF THE INVENTION According to this invention, the brake control apparatus which can ensure a highly accurate braking force can be provided.

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

(First embodiment)
[Schematic configuration of brake control device]
FIG. 1 is a system diagram showing a brake control device 10 according to the first embodiment. A brake control device 10 shown in FIG. 1 constitutes an electronically controlled brake system for a vehicle, and independently and independently controls the brakes of the four wheels of the vehicle according to the operation of the brake pedal 12 as a brake operation member by the driver. Set optimally. That is, the brake control device 10 can control the braking force applied to the wheels provided on the vehicle.

  The brake pedal 12 is connected to a master cylinder 14 that sends out brake fluid as a working fluid (working fluid) in response to a depression operation by a driver. The brake pedal 12 is provided with a stroke sensor 46 for detecting the depression stroke.

  Further, a reservoir tank 26 is connected to the master cylinder 14, and a reaction force corresponding to the operating force of the brake pedal 12 by the driver is applied to one output port of the master cylinder 14 via the on-off valve 23. A stroke simulator 24 to be created is connected. The on-off valve 23 is a normally closed solenoid valve that is closed when not energized and is switched to an open state when an operation of the brake pedal 12 by the driver is detected.

  A brake hydraulic pressure control pipe 16 for the right front wheel is connected to one output port of the master cylinder 14. The brake hydraulic control pipe 16 is connected to a wheel cylinder 20FR for the right front wheel that applies a braking force to the right front wheel (not shown) using the hydraulic pressure of the working fluid. A brake hydraulic pressure control pipe 18 for the left front wheel is connected to the other output port of the master cylinder 14, and the brake hydraulic pressure control pipe 18 uses the hydraulic pressure of the working fluid with respect to the left front wheel (not shown). It is connected to a wheel cylinder 20FL for the left front wheel that applies a braking force.

  A right electromagnetic on-off valve 22FR is provided in the middle of the brake hydraulic control pipe 16 for the right front wheel, and a left electromagnetic on-off valve 22FL is provided in the middle of the brake hydraulic control pipe 18 for the left front wheel. The right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL are both open when not energized, and are normally open when the operation of the brake pedal 12 by the driver is detected. It is.

  A right master pressure sensor 48FR for detecting the master cylinder pressure on the right front wheel side is provided in the middle of the brake hydraulic control pipe 16 for the right front wheel. A left master pressure sensor 48FL for measuring the master cylinder pressure on the left front wheel side is provided.

  In the brake control apparatus 10, when the brake pedal 12 is depressed by the driver, the stroke operation amount is detected by the stroke sensor 46. The master detected by the right master pressure sensor 48FR and the left master pressure sensor 48FL is detected. The depressing operation force (depressing force) of the brake pedal 12 can also be obtained from the cylinder pressure. As described above, it is preferable from the viewpoint of fail-safe that the master cylinder pressure is monitored by the two of the right master pressure sensor 48FR and the left master pressure sensor 48FL assuming the failure of the stroke sensor 46.

  On the other hand, one end of a hydraulic supply / discharge pipe 28 is connected to the reservoir tank 26, and a suction port of an oil pump 34 driven by a motor 32 is connected to the other end of the hydraulic supply / discharge pipe 28. . The discharge port of the oil pump 34 is connected to a high pressure pipe 30 as a fluid path through which the brake fluid flows, and an accumulator 50 and a relief valve 53 are connected to the high pressure pipe 30. In the present embodiment, a reciprocating pump having two or more pistons (not shown) that are reciprocally moved by the motor 32 is employed as the oil pump 34. Further, as the accumulator 50, an accumulator 50 that converts the pressure energy of the brake fluid into the pressure energy of an enclosed gas such as nitrogen is stored. The accumulator 50 is accumulated by compressing the enclosed gas such as nitrogen by the brake fluid supplied from the oil pump 34.

  The accumulator 50 stores the brake fluid that has been pressurized to, for example, about 14 to 22 MPa by the oil pump 34. Further, the valve outlet of the relief valve 53 is connected to the hydraulic supply / discharge pipe 28. When the pressure of the brake fluid in the accumulator 50 is abnormally increased to, for example, about 25 MPa, the relief valve 53 is opened and the high-pressure brake is opened. The fluid is returned to the hydraulic supply / discharge pipe 28.

  Further, the high-pressure pipe 30 is provided with an accumulator pressure sensor 51 that detects the outlet pressure of the accumulator 50, that is, the pressure of the brake fluid in the accumulator 50. In other words, the accumulator pressure sensor 51 detects the pressure of the brake fluid in the high pressure pipe 30.

  The high pressure pipe 30 is connected to the right front wheel wheel cylinder 20FR, the left front wheel wheel cylinder 20FL, the right rear wheel wheel cylinder 20RR, and the left rear wheel through the pressure increasing valves 40FR, 40FL, 40RR, 40RL. It is connected to the cylinder 20RL. Hereinafter, the wheel cylinders 20FR to 20RL will be collectively referred to as “wheel cylinders 20”, and the pressure increase valves 40FR to 40RL will be appropriately collectively referred to as “pressure increase valves 40”. Each of the pressure increasing valves 40 is a normally closed electromagnetic flow control valve (linear valve) that is closed when not energized and is used to increase the pressure of the wheel cylinder 20 as necessary.

  A disc brake unit is provided for each wheel of the vehicle (not shown), and each disc brake unit generates a braking force by pressing the brake pad against the disc by the action of the wheel cylinder 20.

  Further, the wheel cylinder 20FR for the right front wheel and the wheel cylinder 20FL for the left front wheel are connected to the hydraulic supply / discharge pipe 28 via the pressure reducing valve 42FR or 42FL, respectively. The pressure reducing valves 42FR and 42FL are normally closed electromagnetic flow control valves (linear valves) used for pressure reduction of the wheel cylinders 20FR and 20FL as necessary. On the other hand, the wheel cylinder 20RR for the right rear wheel and the wheel cylinder 20RL for the left rear wheel are connected to the hydraulic supply / discharge pipe 28 via a pressure reducing valve 42RR or 42RL which is a normally open electromagnetic flow control valve. . Hereinafter, the pressure reducing valves 42FR to 42RL are collectively referred to as “pressure reducing valve 42” as appropriate.

  As shown in FIG. 1, the brake control device 10 according to the present embodiment includes wheel cylinders corresponding to the wheel cylinders 20FR to 20RL for the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel, respectively. Cylinder pressure sensors 44FR, 44FL, 44RR and 44RL for detecting wheel cylinder pressure which is the pressure of the brake fluid acting on the cylinder 20 are provided. Hereinafter, the cylinder pressure sensors 44FR to 44RL are collectively referred to as “cylinder pressure sensor 44” as appropriate.

  The right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, and the like constitute the hydraulic actuator 80 of the brake control device 10. The oil pump 34, the accumulator 50, and the like constitute a hydraulic power source 90 of the brake control device 10. The hydraulic actuator 80 and the hydraulic power source 90 are controlled by an electronic control unit (hereinafter referred to as “ECU”) 200. The ECU 200 includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for data storage and program execution, an input / output interface, a memory, and the like.

  In the present embodiment, the hydraulic pressure circuit 100 is configured by the pressure increasing valve 40, the pressure reducing valve 42, and a flow path communicating these. The hydraulic circuit 100 controls the supply of brake fluid to the wheel cylinder 20 by controlling the opening and closing of the pressure increasing valve 40 and the pressure reducing valve 42. The hydraulic circuit 100 is in communication with the oil pump 34 and the accumulator 50 via the high pressure pipe 30. In the present embodiment, an accumulator 70 different from the accumulator 50 described above is provided in the middle of the high-pressure pipe 30 that connects the hydraulic power source 90 and the hydraulic actuator 80. Further, the accumulator 70 is disposed at a position closer to the hydraulic circuit 100 than the accumulator 50.

  As a result, when there is a braking request in a state where the accumulator 50 and the accumulator 70 are sufficiently boosted to, for example, about 14 to 22 MPa by the oil pump 34, compared to the case where the brake fluid is supplied from the accumulator 50 to the hydraulic circuit 100. Thus, the brake fluid can be supplied to the hydraulic circuit 100 from the accumulator 70 closer to the hydraulic circuit 100. Therefore, the brake control apparatus 10 can reduce the response delay of the pressure fluctuation of the brake fluid pressure in the wheel cylinder 20 and can secure a highly accurate braking force.

  Next, the pressure change of the two accumulators when accumulating pressure in the brake control device 10 according to the present embodiment will be described. FIG. 2 is a graph showing pressure fluctuations of the accumulators provided in the brake control device according to the first embodiment.

Curve C1 shown in FIG. 2 (two-dot chain line), the filling pressure indicates the variation of pressure in the case of using in addition to the accumulator 50 is P _1, the accumulator 70 of the same volume with the same filling pressure P _1. In this case, the accumulator 50 and the accumulator 70 accumulate pressure similarly. Curve C2 (dashed line), the filling pressure is in addition to the accumulator 50 is P _1, the volume of gas in the filling pressure P ₁ of the accumulator 50 in which the filling pressure P ₁ is set to the same filling pressure P ₁ The fluctuation of the pressure when the accumulator 70 smaller than the gas volume is used is shown.

According to the curve C1, the time required to reach the control permission pressure P ₃ is t _1. On the other hand, according to the curve C2, a _{t 2} time required to reach the control permission pressure _{P 3 (t 2 <t 1} ). Therefore, by arranging the accumulator 70 having a smaller volume than the accumulator 50 in the vicinity of the hydraulic circuit 100, the accumulator 70 having the same volume as that of the accumulator 50 is disposed in the vicinity of the hydraulic circuit 100. it can boost the accumulator 50 and the accumulator 70 to the control permission pressure P ₃ at time. Here, the control permission pressure can be regarded as a pressure at which a sufficient braking force can be generated using the accumulated accumulator. Further, the accumulator 70 can be reduced in size, and for example, the accumulator 70 can be easily disposed near the hydraulic circuit 100 even in an engine room where space is limited.

Curve C3 (solid line) shown in FIG. 2, the filling pressure is in addition to the accumulator 50 is P _1, the filling pressure of the gas in which filling pressure P ₂ is set to filling pressure P ₂ higher than P ₁ volume Shows the fluctuation of the pressure when the accumulator 70 is smaller than the gas volume at the sealed pressure P ₁ of the accumulator 50. According to the curve C3, the time required to reach the control permission pressure P ₃ is t _3. More specifically, when the oil pump 34 is driven, the pressure first rises from the accumulator 50 having a low enclosure pressure, and becomes the same enclosure pressure P ₂ as that of the accumulator 70 at time t ₄ . Thereafter, the accumulator 50 and the accumulator 70 will pressure accumulated in the same way, to reach the control permission pressure P ₃ at time t _3. Therefore, by disposing the accumulator 70 high filling pressure from the accumulator 50 with a small volume in the vicinity of the hydraulic circuit 100 can boost the accumulator 50 and the accumulator 70 to the control permission pressure P ₃ in a shorter time.

(Second Embodiment)
FIG. 3 is a system diagram showing a brake control device 110 according to the second embodiment. Below, description of the structure similar to the brake control apparatus 10 which concerns on 1st Embodiment is abbreviate | omitted, and a difference is mainly demonstrated.

  The brake control device 110 according to the present embodiment differs from the brake control device 10 according to the first embodiment in that a check valve 52 and a check valve 72 are provided between the accumulator 50 and the accumulator 70 and the high-pressure pipe 30, respectively. It has been. The check valve 52 functions as a first control valve that controls the supply of brake fluid from the accumulator 50 to the hydraulic circuit 100 and the supply of brake fluid from the oil pump 34 to the accumulator 50, and the check valve 72 is the accumulator 70. Functions as a second control valve that controls the supply of brake fluid to the hydraulic circuit 100 and the supply of brake fluid from the oil pump 34 to the accumulator 70.

  FIG. 4 is a diagram schematically showing the check valve 52 according to the present embodiment. Since the check valve 72 has the same configuration as the check valve 52, the description thereof is omitted. The check valve 52 is provided with an inlet-side channel 54 and an outlet-side channel 55, and check valves 56 and 57 are arranged in the middle of each channel. Therefore, ECU 200 can control pressure accumulation in one or both of accumulator 50 and accumulator 70 by controlling check valve 52 and check valve 72.

[Control block diagram]
FIG. 5 is a control block diagram of the brake control device 110 according to the second embodiment. In the following description, a function for controlling the accumulator among various functions of the ECU 200 will be mainly described.

  As shown in FIG. 5, the ECU 200 is electrically connected to the check valves 52 and 72 described above, a relay 58 that supplies power to the motor 32, and the like. The check valves 52 and 72 are controlled to be opened and closed by a valve control unit 201 built in the ECU 200.

  Further, the ECU 200 is given a signal indicating the wheel cylinder pressure in the accumulator 50 and the accumulator 70 connected to the high-pressure pipe 30 from the accumulator pressure sensor 51, and indicates that the vehicle is started from the ignition sensor 60. A signal is given. Further, the ECU 200 is supplied with a signal indicating information correlated with the temperature of the brake fluid from the temperature sensor 62 as temperature information detecting means. Here, the temperature sensor 62 may be provided in the hydraulic circuit 100 or the high-pressure pipe 30 in order to directly detect the temperature of the brake fluid, or may be an outside air temperature sensor that can indirectly estimate the temperature of the brake fluid. May be.

  In the brake control device 110 configured as described above, the accumulator control unit 202 built in the ECU 200 determines whether or not to accumulate pressure in the accumulator 50 or the accumulator 70 based on a signal given from the ignition sensor 60 at the time of starting. judge. The accumulator control unit 202 controls the check valves 52 and 72 and the motor 32 via the valve control unit 201 and the pump control unit 204 as necessary. Hereinafter, specific description will be given with reference to a flowchart.

[Accumulator pressure accumulation method at startup]
FIG. 6 is a flowchart showing the accumulator pressure accumulation method when the brake control device 110 is started. When the driver turns on the ignition keys, ECU 200 compares the environmental temperature T ₁ of the predetermined temperature T ₀ which is calculated on the basis of a signal given from the temperature sensor 62 (S10). Here, the predetermined temperature T ₀ may be, for example, 0 ° C., which is below freezing point, or −30 in an extremely low temperature environment where the viscosity of the brake fluid is further increased, as a threshold value at which the viscosity of the brake fluid increases in a low temperature environment. It is good also as a certain value in the range of ° C to -40 ° C.

If the environmental temperature T ₁ is equal to or higher than the predetermined temperature T ₀ (S10 of No), the brake fluid due to temperature decrease viscosity increase is small, can supply brake fluid to the hydraulic circuit 100 with the accumulator 50 of the braking Since the response delay is within the allowable range, the process proceeds to S20 described later.

On the other hand, when the ambient temperature T ₁ is lower than the predetermined temperature T ₀ (Yes in S10), since the accumulator to effect large accumulator 70 increase in viscosity of the brake fluid due to temperature decrease is required, the valve control unit 201 The check valve 52 is closed and the check valve 72 is opened (S12). In this state, the accumulator control unit 202, in response to the signal sent from the accumulator pressure sensor 51 detects the pressure _{P AC2} of the accumulator 70 connected to the high-pressure pipe 30 _{(S14), P AC2} and control permission pressure _{P 3} Are compared (S16).

If P _AC2 is lower than the control permission pressure _{P 3} (Yes in S16), the pump control unit 204 drives and supplies the current to the motor 32 by controlling the relay 58 (S18). _Then, until _{P AC2} is control permission pressure _{P 3} or more, the process is repeated from S14 to S18. If P _AC2 becomes control permission pressure _{P 3} or more (No in S16), the valve control unit 201 opens the check valve 52 to close the check valve 72 (S20). In this state, the accumulator control unit 202 detects the pressure _{PAC1 of the} accumulator 50 connected to the high-pressure pipe 30 based on the signal given from the accumulator pressure sensor 51 (S22), and _PAC1 and the control permission pressure comparing the P ₃ (S24).

If P _AC1 is less than the control permission pressure _{P 3} (Yes in S24), the pump control unit 204 continues to supply current to the motor 32 by controlling the relay 58. _Then, until _{P AC1} is control permission pressure _{P 3} or more, the process is repeated from S22 to S24. If P _AC1 becomes control permission pressure _{P 3} or more (No in S24), the pump control unit 204 stops the current supplied to the motor 32 by controlling the relay 58 and stops the motor 32 (S26).

  Therefore, according to the accumulator pressure accumulating method shown in FIG. 6, the accumulator 50 is closer to the hydraulic circuit 100 than the accumulator 50 in an environment where the response delay of braking exceeds an allowable range when only the accumulator 50 is operated below the predetermined temperature. Accumulator 70 can be accumulated first, and in a shorter time, brake control device 110 is in a state where the response delay of braking can be within an allowable range.

  The brake control device 110 can supply brake fluid from the accumulator 70 provided at a position closer to the hydraulic circuit 100 than the accumulator 50 to the hydraulic circuit 100, so that the brake fluid is supplied from the accumulator 50 to the hydraulic circuit 100. Compared with the case of supplying, it is possible to reduce the response delay of the pressure fluctuation of the brake fluid in the hydraulic circuit 100 and to secure a highly accurate braking force. In other words, in a low temperature environment, braking with less response delay is possible using the brake fluid supplied from the accumulator 70 instead of the brake fluid supplied from the accumulator 50 that easily generates a response delay.

  Further, when the brake control device 110 detects a braking request from a signal given from a stroke sensor (not shown) immediately after the start of the ECU 200 in a low temperature environment where the vehicle is not warmed, before the accumulator 50 is accumulated to the control permission pressure. However, if the accumulator 70 is accumulated to the control permission pressure, the brake fluid is supplied from the accumulated accumulator 70 to the hydraulic circuit 100 by controlling the opening and closing of the check valve 52 and the check valve 72. Can do. Thereby, the brake control apparatus 110 can ensure a highly accurate braking force even immediately after starting in a low temperature environment.

  Next, the pressure change of the two accumulators when accumulating pressure in the brake control device 110 according to the present embodiment will be described. FIG. 7 is a graph showing pressure fluctuations of the accumulators provided in the brake control device according to the second embodiment.

Curve C4, C4 shown in FIG. 7 '(two-dot chain line), the filling pressure is in addition to the accumulator 50 is P _1, the brake control device 110 having the accumulator 70 of the same volume with the same filling pressure P _1, FIG. 6 shows the fluctuation of pressure when pressure is accumulated by the pressure accumulation method described in FIG. Further, (dashed line) curve C5, C5 'is charged pressure in addition to the accumulator 50 is P _1, the filling pressure of the volume accumulator 50 of the gas in which the filling pressure P ₁ is set to the same filling pressure P ₁ in the brake control device 110 having a smaller accumulator 70 than the volume of the gas in the P _1, it shows the variation of pressure in the case where the accumulator by accumulating the method shown in FIG. In the following description, for convenience of explanation, a case will be described in which the pressure of each accumulator immediately after the vehicle is started is an enclosed pressure.

According to the pressure accumulation method described in FIG. 6, when the start of the vehicle is detected, pressure accumulation is started with the check valve 52 closed and the check valve 72 opened. As a result, the accumulator 70 is gradually accumulated pressure to reach the control permission pressure P ₃ as curve C4. According to the curve C4, the time required to reach the control permission pressure P ₃ is t _5. When the pressure in the accumulator 70 reaches the control permission pressure P _3, the check valve 72 is closed, the check valve 52 is opened. Then, the accumulator 50 is gradually accumulated pressure to reach the control permission pressure P ₃ as curve C4 '. According to the curve C4 ', the time required to reach the control permission pressure P ₃ is t _1.

On the other hand, when the brake control device 110 the volume of gas with a smaller accumulator 70 than the volume of gas in the filling pressure P ₁ of the accumulator 50 in the filling pressure P _1, the starting of the vehicle is detected, the check valve 52 initially is Accumulation is started with the closed check valve 72 open. As a result, the accumulator 70 is gradually accumulated pressure to reach the control permission pressure P ₃ as curve C5. According to the curve C5, a _{t 6} of time required to reach the control permission pressure _{P 3 (t 6 <t 5} ). Thereby, the pressure accumulation of the accumulator 70 can be performed in a shorter time. When the pressure in the accumulator 70 reaches the control permission pressure P _3, the check valve 72 is closed, the check valve 52 is opened. Then, the accumulator 50 is gradually accumulated pressure to reach the control permission pressure P ₃ as curve C5 '. According to the curve C5 ', control permission pressure time required to reach the _{P 3} is a _{t 7 (t 7 <t 1} ).

The curve C6, C6 shown in FIG. 7 '(solid line), the filling pressure is in addition to the accumulator 50 is _{P 1,} the filling pressure is in which filling pressure _{P 2} is set to filling pressure _{P 2} higher than _{P 1} in the brake control apparatus 110 the volume of gas with a smaller accumulator 70 than the volume of gas in the filling pressure P ₁ of the accumulator 50, shows the variation in the case where the accumulator by accumulating the method described in FIG. In this case, the accumulator 70 needs only a small amount of brake fluid to accumulate pressure to such an extent that a sufficient braking force can be generated in the wheel cylinder 20. Therefore, if the amount of brake fluid supplied from the oil pump 34 per unit time is constant, the accumulator 70 is accumulated to a predetermined control permission pressure in a shorter time.

Specifically, when the start of the vehicle is detected, pressure accumulation is started with the check valve 52 closed and the check valve 72 opened. As a result, the accumulator 70 is gradually accumulated pressure to reach the control permission pressure P ₃ as curve C6. According to the curve C6, the time required to reach the control permission pressure _{P 3} is _{t 8 (t 8 <t 6} ). Thereby, the pressure accumulation of the accumulator 70 can be performed in a shorter time. When the pressure in the accumulator 70 reaches the control permission pressure P _3, the check valve 72 is closed, the check valve 52 is opened. Then, the accumulator 50 is gradually accumulated pressure to reach the control permission pressure P ₃ as curve C6 '. According to the curve C6 ', the time required to reach the control permission pressure _{P 3} is a _{t 9 (t 9 <t 7} ).

  Therefore, the brake control device 110 according to the present embodiment employs the accumulator 70 in which the enclosed pressure is set to be higher than the enclosed pressure of the accumulator 50 and the volume is smaller than the volume of the accumulator 50, so that the time can be shortened. Accumulator 70 can be accumulated up to the control permission pressure. Further, the miniaturized accumulator 70 can be easily disposed even when the layout in the vicinity of the hydraulic circuit 100 is limited.

  Further, by disposing the accumulator 50 in the vicinity of the oil pump 34, the pulsation of the pump can be appropriately attenuated, and the transmission of the pulsating sound can be reduced. Further, by using the accumulator 50 and the accumulator 70 at the same time, it is possible to generate a sufficient braking force without a response delay even in the case of sudden braking.

  In the above, this invention was demonstrated based on each embodiment. It is to be understood by those skilled in the art that these embodiments are exemplifications, and various modifications can be made to combinations of components and processes, and such modifications are within the scope of the present invention.

It is a systematic diagram showing a brake control device according to the first embodiment. It is a graph which shows the pressure fluctuation of each accumulator with which the brake control device concerning a 1st embodiment is provided. It is a systematic diagram which shows the brake control apparatus which concerns on 2nd Embodiment. It is the figure which showed typically the check valve which concerns on this Embodiment. It is a control block diagram of a brake control device according to a second embodiment. It is a flowchart which shows the pressure accumulation method of the accumulator at the time of starting of a brake control apparatus. It is a graph which shows the pressure fluctuation of each accumulator with which the brake control device concerning a 2nd embodiment is provided.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Brake control apparatus, 12 Brake pedal, 14 Master cylinder, 20 Wheel cylinder, 30 High pressure pipe, 32 Motor, 34 Oil pump, 40 Pressure increase valve, 42 Pressure reduction valve, 44 Cylinder pressure sensor, 46 Stroke sensor, 50 Accumulator, 51 Accumulator Pressure sensor, 52 check valve, 58 relay, 60 ignition sensor, 62 temperature sensor, 70 accumulator, 72 check valve, 80 hydraulic actuator, 90 hydraulic power source, 100 hydraulic circuit, 110 brake control device, 200 ECU, 201 valve control Section, 202 accumulator control section, 204 pump control section.

Claims (6)

A pump driven by a motor;
A first accumulator that accumulates pressure by being compressed by a working fluid supplied from the pump;
A hydraulic circuit for controlling the supply of the working fluid to the braking force applying means for applying a braking force to the wheel using the hydraulic pressure of the working fluid;
A fluid path communicating the pump, the first accumulator and the hydraulic circuit;
Pressure detecting means for detecting the pressure of the working fluid in the fluid path;
A second accumulator which is provided in a position closer to the hydraulic circuit than the first accumulator in the fluid path, and accumulates pressure when the sealed gas is compressed by the working fluid supplied from the pump;
A first control valve that controls supply of working fluid from the first accumulator to the hydraulic circuit and supply of working fluid from the pump to the first accumulator;
A second control valve that controls supply of working fluid from the second accumulator to the hydraulic circuit and supply of working fluid from the pump to the second accumulator;
A controller for controlling opening and closing of the first control valve and the second control valve,
The control unit controls opening and closing of the first control valve and the second control valve so that a working fluid is supplied from the second accumulator that has accumulated pressure to a hydraulic circuit. Brake control device.   The control unit can control opening and closing of the first control valve and the second control valve so that pressure accumulation in the second accumulator is started before the first accumulator. Item 4. The brake control device according to item 1.   The said 2nd accumulator is comprised so that the volume of the gas in the enclosure pressure of this 2nd accumulator may become smaller than the volume of the gas in the enclosure pressure of the said 1st accumulator. The brake control device according to 2.   4. The brake control device according to claim 1, wherein an enclosure pressure of the second accumulator is set higher than an enclosure pressure of the first accumulator. 5. A temperature information detecting means for detecting information correlated with the temperature of the working fluid;
When the temperature of the working fluid calculated based on the detected information is lower than a predetermined temperature, the control unit starts the pressure accumulation in the second accumulator before the first accumulator. The brake control device according to any one of claims 2 to 4, wherein opening and closing of the first control valve and the second control valve are controlled.   When detecting that the ignition is turned on, the control unit drives the pump with the first control valve closed and the second control valve opened, and the supplied working fluid supplies the first control valve. 2. After accumulating the second accumulator to a predetermined pressure, the second control valve is closed and the first control valve is opened to accumulate the first accumulator to a predetermined pressure. The brake control device according to any one of 2 to 5.

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