JP2011025929A - Vehicle motion control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle motion control apparatus capable consistently securing deceleration targeted for brake operation by a driver even if automatic pressurization control is performed. <P>SOLUTION: The apparatus is applied to a vehicle brake apparatus provided with a hydraulic booster operated by utilizing accumulator hydraulic pressure Pacc that is adjusted to predetermined high pressure (not lower than a lower limit value Pon) by the drive control of a motor M (a hydraulic pump). The apparatus executes automatic pressurization control (oversteer (OS) suppression control) by controlling a plurality of solenoid valves by the use of the Pacc. An increasing slope of the brake hydraulic pressure at the OS suppression control is determined in principle on the basis of a vehicle motion state (vehicle body slip angle). However, when "Pacc at an OS suppression control starting time is larger than the lower limit value of Pacc (the assist limit value Passist) required for the assist of the brake operation by the hydraulic booster, and below the reference liquid pressure Pref lower than Pon", the increasing slope is restricted to a value not larger than a predetermined restriction value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle motion control apparatus that performs automatic pressurization control for generating wheel cylinder fluid pressure for controlling vehicle motion independently of a driver's brake operation using an accumulator fluid pressure.

  Conventionally, a hydraulic pump, a motor that drives the hydraulic pump, an accumulator that stores the brake fluid that has been boosted by driving the hydraulic pump by the motor, and the pressure of the brake fluid that is stored in the accumulator (hereinafter, “ 2. Description of the Related Art A brake device including a hydraulic pressure booster that assists a driver to operate a brake pedal using an accumulator hydraulic pressure is widely known (see, for example, Patent Document 1 below).

  The device described in the above document drives a motor (and therefore a hydraulic pump) when the accumulator hydraulic pressure becomes less than a predetermined lower limit, and the accumulator hydraulic pressure exceeds a predetermined upper limit greater than the lower limit. The hydraulic pump is configured to stop when As a result, the accumulator hydraulic pressure is larger than the lower limit value of the accumulator hydraulic pressure necessary for sufficient assistance of the brake pedal operation by the hydraulic booster (hereinafter referred to as “assist limit value”). In principle, the pressure is adjusted to a pressure within the range between the upper limit values (high pressure).

  Furthermore, the device described in the above document includes a plurality of electromagnetic valves for adjusting the brake fluid pressure in the wheel cylinder (hereinafter referred to as “wheel cylinder fluid pressure”). Thereby, in addition to being able to perform the known anti-skid control (henceforth "ABS control") by controlling the above-mentioned plurality of solenoid valves, the device described in the above-mentioned literature can be executed. Automatic generation of wheel cylinder hydraulic pressure for controlling the movement of the vehicle independently of the brake operation by the driver by controlling the plurality of solenoid valves while utilizing the accumulator hydraulic pressure adjusted to the high pressure. Pressurization control (for example, oversteer suppression control) can be executed.

  By the way, for example, when ABS control is executed or when an operation in which the brake pedal is repeatedly turned on and off (hereinafter referred to as “pumping brake operation”) is executed, the brake fluid pressure is increased. The brake fluid in the circuit is returned to the reservoir. As a result, the accumulator hydraulic pressure maintained at the high pressure is often reduced to be less than the lower limit. In this case, since the hydraulic pump starts to be driven, normally, the accumulator hydraulic pressure immediately increases thereafter and returns to a value equal to or higher than the lower limit value.

  However, when the degree of increase / decrease of the wheel cylinder hydraulic pressure in the ABS control is very large and the cycle is short, or when the ON / OFF cycle of the brake operation in the pumping brake operation is very short, the brake hydraulic pressure The average speed at which the brake fluid in the circuit is returned to the reservoir (hereinafter referred to as “the brake fluid consumption speed”) becomes very fast. In this way, when the brake fluid consumption speed is very high, the accumulator hydraulic pressure is reduced even if the hydraulic pump continues to be driven. As a result, the accumulator hydraulic pressure reaches the vicinity of the assist limit value. Decreasing phenomena can occur.

  As described above, when the automatic pressurization control is started in a state where the accumulator hydraulic pressure is reduced to near the assist limit value, the brake fluid is supplied to the wheel cylinder in order to increase the wheel cylinder hydraulic pressure. As a result, the accumulator hydraulic pressure may further decrease even if the hydraulic pump is continuously driven. As a result, the accumulator hydraulic pressure can be less than the assist limit value.

  In such a case, if the brake pedal operation is performed by the driver until the accumulator hydraulic pressure subsequently returns to the assist limit value or more by the action of the hydraulic pump that is continuously driven, the hydraulic booster As a result, there is a problem that the assist force of the brake pedal operation due to cannot be sufficiently generated, and as a result, the target deceleration for the brake operation of the driver may not be obtained.

JP 2004-066941 A

  The present invention has been made in order to cope with the above-described problem, and an object of the present invention is to provide a vehicle that can stably secure a target deceleration for the brake operation of the driver even when the automatic pressurization control is executed. It is to provide a motion control device.

  A first motion control device for a vehicle according to the present invention stores a hydraulic pump, drive control means for driving the hydraulic pump, and brake fluid boosted by driving the hydraulic pump by the drive control means. An accumulator that operates, a hydraulic booster that assists the brake operation by the driver using the accumulator hydraulic pressure that is the pressure of the brake fluid stored in the accumulator, and a wheel cylinder hydraulic pressure that is the brake hydraulic pressure in the wheel cylinder The present invention is applied to a brake device for a vehicle provided with pressure adjusting means for adjusting the pressure and detecting means for detecting the accumulator hydraulic pressure.

  The first motion control device for a vehicle according to the present invention controls the motion of the vehicle independently of a brake operation by the driver by controlling the pressure adjusting means using the accumulator hydraulic pressure. Automatic pressurization control means for performing automatic pressurization control for generating the wheel cylinder hydraulic pressure is characterized in that the automatic pressurization control is performed when the detected accumulator hydraulic pressure is less than a predetermined hydraulic pressure. There is further provided limiting means for limiting the degree of increase in the wheel cylinder hydraulic pressure generated by the above.

  More specifically, the drive control means drives the hydraulic pump when the detected accumulator hydraulic pressure becomes less than a predetermined lower limit, and the accumulator hydraulic pressure is greater than the lower limit. The hydraulic pump is configured to stop when the upper limit value of the hydraulic pressure is exceeded, and the restricting means is smaller than the lower limit value as the predetermined hydraulic pressure, and the brake operation by the hydraulic pressure booster. A value larger than the lower limit value of the accumulator hydraulic pressure (that is, the assist limit value) necessary for assisting the power is used.

  According to this, when the automatic pressurization control is started in a state where the accumulator hydraulic pressure is less than the predetermined hydraulic pressure (for example, a value smaller than the lower limit value and larger than the assist limit value), The degree of increase in the wheel cylinder hydraulic pressure generated by the automatic pressurization control is limited. Therefore, the supply speed of the brake fluid supplied to the wheel cylinder in order to increase the wheel cylinder hydraulic pressure can be limited.

  This means that the occurrence of a situation in which the accumulator hydraulic pressure further decreases while the wheel cylinder hydraulic pressure is increased by the automatic pressurization control can be suppressed. Therefore, the occurrence of a situation where the accumulator hydraulic pressure becomes less than the assist limit value can be suppressed, and as a result, the assist force of the brake operation by the hydraulic pressure booster is stably and sufficiently secured even when the automatic pressurization control is executed. obtain. That is, it is possible to stably ensure the deceleration targeted for the brake operation of the driver.

  The second motion control device for a vehicle according to the present invention is the same as the first motion control device described above, in addition to the same hydraulic pump, drive control means, accumulator, pressure regulation means, and detection means. The present invention is applied to a vehicle brake device provided with a brake operation signal output means (for example, a brake pedal operation stroke sensor, a brake pedal operation force sensor, etc.) that detects and outputs a signal corresponding to the brake operation.

  The second motion control device for a vehicle according to the present invention controls the pressure adjusting means using the accumulator hydraulic pressure to respond to a signal output from the brake operation signal output means (that is, by a driver). Brake control means for performing brake-by-wire control for generating wheel cylinder hydraulic pressure (according to the brake operation), and automatic pressurization control means that is the same as the first motion control device. Further, it is further provided with the same limiting means as the first motion control device.

  More specifically, the drive control means drives the hydraulic pump when the detected accumulator hydraulic pressure becomes less than a predetermined lower limit, and the accumulator hydraulic pressure is greater than the lower limit. The hydraulic pump is configured to stop when the upper limit value is exceeded, and the limiting means is smaller than the lower limit value as the predetermined hydraulic pressure, and the brake-by-wire control is performed. The wheel cylinder hydraulic pressure range required for execution is configured to use a value larger than the upper limit value (hereinafter referred to as “normal hydraulic pressure upper limit value”).

  The normal hydraulic pressure upper limit value is set to a value equal to a target wheel cylinder hydraulic pressure corresponding to, for example, a case where the driver's assumed maximum brake operation (operation amount, operation stroke, operation force) is performed. . When the normal hydraulic pressure upper limit value is set in this way, the accumulator hydraulic pressure becomes less than the normal hydraulic pressure upper limit value when the brake operation of the driver is performed when the brake operation close to the assumed maximum brake operation is performed. This means that the wheel cylinder hydraulic pressure aimed at cannot be generated.

  According to the above configuration, the automatic pressurization control is started in a state where the accumulator hydraulic pressure is less than the predetermined hydraulic pressure (that is, a value smaller than the lower limit value and larger than the normal hydraulic pressure upper limit value). In this case, the degree of increase in the wheel cylinder hydraulic pressure generated by the automatic pressurization control is limited. As a result, as in the first motion control device, it is possible to suppress the occurrence of a situation in which the accumulator hydraulic pressure further decreases while the wheel cylinder hydraulic pressure is increased by the automatic pressurization control.

  Therefore, the occurrence of a situation where the accumulator hydraulic pressure is less than the upper limit value of the normal hydraulic pressure can be suppressed. As a result, even if the automatic pressurization control is executed, the wheel cylinder hydraulic pressure targeted for the driver's brake operation is not increased. It can be secured stably. That is, it is possible to stably ensure the deceleration targeted for the brake operation of the driver.

  In the first and second motion control devices according to the present invention, when the detected accumulator hydraulic pressure is less than a predetermined hydraulic pressure, the limiting means increases the wheel cylinder hydraulic pressure by the automatic pressurization control. It is preferable that the degree of increase of the wheel cylinder hydraulic pressure generated by the automatic pressurization control is limited so that the accumulator hydraulic pressure increases at least while the accumulator hydraulic pressure is increased.

  According to this, it can be guaranteed that the accumulator hydraulic pressure increases while the wheel cylinder hydraulic pressure is increased by the automatic pressurization control. Therefore, the occurrence of a situation where the accumulator hydraulic pressure is less than the assist limit value or less than the normal hydraulic pressure upper limit value can be more reliably suppressed.

  In any of the above-described motion control devices according to the present invention, in order to “limit the degree of increase in wheel cylinder hydraulic pressure generated by automatic pressurization control”, specifically, for example, by automatic pressurization control. What is necessary is just to restrict | limit the increase gradient of the wheel cylinder hydraulic pressure to perform below to a predetermined gradient.

  In this case, specifically, for example, the increasing gradient of the wheel cylinder hydraulic pressure generated by the automatic pressurization control is usually determined based on the motion state of the vehicle or the like. When the accumulator hydraulic pressure is less than the predetermined hydraulic pressure, and the increasing gradient of the wheel cylinder hydraulic pressure determined based on the motion state of the vehicle exceeds the predetermined gradient, the increasing gradient is equal to the predetermined gradient. It is changed (restricted) to a value.

  Further, when the automatic pressurizing control means increases the wheel cylinder hydraulic pressure by the automatic pressurizing control, the wheel cylinder and the pressure increasing control for controlling the pressure adjusting means to increase the wheel cylinder hydraulic pressure. Consider a case in which the holding control for holding the hydraulic pressure is alternately executed.

  In this case, specifically, in order to “limit the increase gradient of the wheel cylinder hydraulic pressure generated by the automatic pressurization control to a predetermined gradient or less”, specifically, for example, the time during which the pressure increase control is continued and the holding control are performed. What is necessary is just to restrict | limit the ratio of the time which continues the same pressure increase control with respect to the sum of the time to continue to below predetermined value. Thereby, the average increase gradient of the wheel cylinder hydraulic pressure generated by the automatic pressurization control can be limited to a predetermined gradient or less.

1 is a schematic configuration diagram of a vehicle equipped with a brake device including a vehicle motion control device according to a first embodiment of the present invention. It is a schematic block diagram of the brake fluid pressure control apparatus shown in FIG. Changes in brake switch output, accumulator hydraulic pressure, motor drive status, and hydraulic pressure for oversteer suppression control when oversteer suppression control is started when the accumulator hydraulic pressure is reduced due to execution of ABS control FIG. 6 is a time chart showing a case where the brake operation is performed in a state where the accumulator hydraulic pressure is lowered below the assist limit value. 3 is a flowchart showing a routine for calculating wheel speed and the like executed by a CPU shown in FIG. 1. 3 is a flowchart showing a routine for performing oversteer suppression control executed by a CPU shown in FIG. 1. It is a schematic block diagram of the brake hydraulic pressure control apparatus of the vehicle motion control apparatus which concerns on 2nd Embodiment of this invention. Changes in brake switch output, accumulator hydraulic pressure, motor drive status, and hydraulic pressure for oversteer suppression control when oversteer suppression control is started when the accumulator hydraulic pressure is reduced due to execution of ABS control FIG. 6 is a time chart showing a case where the brake operation is performed in a state where the accumulator hydraulic pressure is lowered below the normal hydraulic pressure upper limit value.

  Hereinafter, a first embodiment of a vehicle motion control apparatus according to the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a schematic configuration of a vehicle equipped with a vehicle brake device 10 including a motion control device according to a first embodiment of the present invention. This vehicle is a front-wheel drive type vehicle in which the two front wheels are drive wheels.

The brake device 10 generates a driving force and transmits the driving force to the driving wheels FL and FR, and a brake fluid pressure control for generating a braking force by the brake fluid pressure on the wheels. The apparatus 30 includes a sensor unit 40 including various sensors, and a motion control device 50.

  The driving force transmission mechanism unit 20 is disposed within an engine 21 that generates driving force and an intake pipe 21a of the engine 21, and an opening degree of a throttle valve TH (throttle valve opening) that makes the opening cross-sectional area of the intake passage variable. A throttle valve actuator 22 composed of a DC motor for controlling the degree TA) and a fuel injection device 23 including an injector for injecting fuel in the vicinity of an intake port (not shown) of the engine 21.

  The driving force transmission mechanism unit 20 is connected to the output shaft of the engine 21 with the input shaft connected thereto, and is connected to the output shaft of the transmission 24 to appropriately distribute the driving force of the engine 21 so that the front wheels FL, FR And a front wheel differential 25 for transmitting to each other.

  As shown in FIG. 2 showing a schematic configuration, the brake fluid pressure control device 30 includes a high pressure generator 31, a brake fluid pressure generator 32 that generates a brake fluid pressure according to the operating force of the brake pedal BP, and wheels. FR brake hydraulic pressure adjustment unit 33, FL brake hydraulic pressure adjustment unit 34, RR brake that can adjust brake hydraulic pressure supplied to wheel cylinders Wfr, Wfl, Wrr, Wrl respectively arranged in FR, FL, RR, RL A hydraulic pressure adjusting unit 35 and an RL brake hydraulic pressure adjusting unit 36 are included.

  The high pressure generator 31 is driven by a motor M, a hydraulic pump HP that is driven by the motor M and sucks and discharges and raises brake fluid in the reservoir RS, and a check valve CVH on the discharge side of the hydraulic pump HP. And an accumulator Acc that stores the brake fluid whose pressure is increased by the same hydraulic pump HP.

The motor M is driven when the hydraulic pressure in the accumulator Acc (hereinafter referred to as “accumulator hydraulic pressure Pacc”) falls below a predetermined lower limit value Pon according to an instruction from a motion control device 50 (CPU 51) described later. The accumulator hydraulic pressure Pacc is stopped when it exceeds a predetermined upper limit value Poff (> Pon). Thereby, the accumulator hydraulic pressure Pacc is adjusted in principle to “a pressure (high pressure) within the range between the lower limit value Pon and the upper limit value Poff”. The lower limit value Pon is sufficiently larger than the lower limit value of the accumulator hydraulic pressure Pacc (hereinafter referred to as “assist limit value Passist”) necessary for sufficient assistance of brake pedal operation by the hydro booster HB described later. Is set to a value.

  Further, a relief valve RV is disposed between the accumulator Acc and the reservoir RS, and when the accumulator hydraulic pressure Pacc is abnormally higher than the upper limit value Poff, the brake fluid in the accumulator Acc is stored in the reservoir RS. It is supposed to be returned to. As a result, the hydraulic circuit of the high pressure generator 31 is protected.

  The brake fluid pressure generating unit 32 includes a hydro booster HB that responds by the operation of the brake pedal BP, and a master cylinder MC that is connected to the hydro booster HB. The hydro booster HB uses the accumulator hydraulic pressure Pacc adjusted from the high pressure supplied from the high pressure generator 31 to assist the operating force of the brake pedal BP at a predetermined ratio, It is transmitted to MC.

  The master cylinder MC generates a master cylinder hydraulic pressure corresponding to the assisted operating force. Further, the hydro booster HB generates a regulator hydraulic pressure corresponding to the assisted operating force, which is substantially the same hydraulic pressure as the master cylinder hydraulic pressure, by inputting the master cylinder hydraulic pressure. Since the configurations and operations of the master cylinder MC and the hydro booster HB are well known, a detailed description thereof will be omitted here. In this way, the master cylinder MC and the hydro booster HB generate the master cylinder hydraulic pressure and the regulator hydraulic pressure according to the operating force of the brake pedal BP, respectively.

  Between the master cylinder MC and each of the upstream side of the FR brake hydraulic pressure adjusting unit 34 and the upstream side of the FL brake hydraulic pressure adjusting unit 34, a control valve SA1 which is a 2-port 2-position switching type normally open electromagnetic on-off valve is provided. Is intervening. Similarly, between the hydro booster HB and each of the upstream side of the RR brake hydraulic pressure adjusting unit 35 and the upstream side of the RL brake hydraulic pressure adjusting unit 36 is a 2-port 2-position switching type normally open electromagnetic on-off valve. A control valve SA2 is interposed.

  The upstream side of the FR brake hydraulic pressure adjusting unit 33 and the upstream side of the FL brake hydraulic pressure adjusting unit 34 are connected to the upstream side of the RR brake hydraulic pressure adjusting unit 35 and the upstream side of the RL brake hydraulic pressure adjusting unit 36, respectively. A control valve SA3, which is a 2-port 2-position switching normally closed electromagnetic on-off valve, is interposed in the pipe line.

  Furthermore, a switching valve STR, which is a 2-port 2-position switching type normally closed electromagnetic on-off valve, is interposed between the high-pressure generator 31 and the pipe line.

  Accordingly, the control valve SA1 and the control valve SA3 (and the switching valve STR) are in the first state in each of the upstream portion of the FR brake fluid pressure adjusting unit 33 and the upstream portion of the FL brake fluid pressure adjusting unit 34. When the master cylinder hydraulic pressure is supplied, the accumulator hydraulic pressure Pacc (high pressure) generated by the high pressure generator 31 when the control valve SA1, the control valve SA3, and the switching valve STR are in the second state (excited state) is It comes to be supplied.

  Similarly, each of the upstream portion of the RR brake fluid pressure adjusting unit 35 and the upstream portion of the RL brake fluid pressure adjusting unit 36 includes a regulator when the control valve SA2, the control valve SA3, and the switching valve STR are in the first state. While the hydraulic pressure is supplied, the accumulator hydraulic pressure Pacc is supplied when the control valve SA2, the control valve SA3, and the switching valve STR are in the second state.

  The FR brake fluid pressure adjusting unit 33 includes a pressure-increasing valve PUfr that is a 2-port 2-position switching type normally open electromagnetic on-off valve and a pressure-reducing valve PDfr that is a 2-port 2-position switching type normally closed electromagnetic on-off valve. When the pressure increasing valve PUfr is in the first state (non-excited state) shown in FIG. 2, the upstream portion of the FR brake fluid pressure adjusting unit 33 and the wheel cylinder Wfr communicate with each other and the second state (excited state). ), The communication between the upstream portion of the FR brake fluid pressure adjusting portion 33 and the wheel cylinder Wfr is cut off. The pressure reducing valve PDfr shuts off the communication between the wheel cylinder Wfr and the reservoir RS when in the first state (non-excited state) shown in FIG. 2, and the wheel cylinder Wfr when in the second state (excited state). It communicates with the reservoir RS.

  As a result, the brake fluid pressure in the wheel cylinder Wfr (wheel cylinder fluid pressure Pwfr) is increased upstream of the FR brake fluid pressure adjusting unit 33 in the wheel cylinder Wfr when both the pressure increasing valve PUfr and the pressure reducing valve PDfr are in the first state. When the pressure of the pressure increasing valve PUfr is in the second state and the pressure reducing valve PDfr is in the first state, the pressure of the FR brake fluid pressure adjusting unit 33 is increased. The brake fluid in the wheel cylinder Wfr is returned to the reservoir RS when the pressure increasing valve PUfr and the pressure reducing valve PDfr are both in the second state. As a result, the pressure is reduced (pressure reduction control).

  Further, a check valve CV1 that allows only one-way flow of brake fluid from the wheel cylinder Wfr side to the upstream portion of the FR brake fluid pressure adjusting unit 33 is disposed in parallel with the pressure increasing valve PUfr. When the control valve SA1 is in the first state and the operated brake pedal BP is released, the wheel cylinder hydraulic pressure Pwfr can be quickly reduced.

  Similarly, the FL brake hydraulic pressure adjusting unit 34, the RR brake hydraulic pressure adjusting unit 35, and the RL brake hydraulic pressure adjusting unit 36 are respectively a pressure increasing valve PUfl and a pressure reducing valve PDfl, a pressure increasing valve PUrr and a pressure reducing valve PDrr, a pressure increasing valve PUrl, and The pressure reducing valve PDrl is configured to control each pressure increasing valve and each pressure reducing valve so that the brake fluid pressure in the wheel cylinder Wfl, the wheel cylinder Wrr, and the wheel cylinder Wrl (the wheel cylinder pressure Pwfl, Pwrr, Pwrl) is controlled. ) Can be controlled to increase pressure, hold, and reduce pressure, respectively. In addition, check valves CV2, CV3, and CV4 that can achieve the same function as the check valve CV1 are arranged in parallel on the pressure increasing valves PUfl, PUrr, and PUrl, respectively.

  The control valve SA2 is provided with a check valve CV5 that allows only one-way flow of the brake fluid from the upstream side to the downstream side in parallel. When the communication between the booster HB and each of the RR brake hydraulic pressure adjusting unit 35 and the RL brake hydraulic pressure adjusting unit 36 is cut off, the wheel cylinder hydraulic pressures Pwrr and Pwrl are controlled by operating the brake pedal BP. The pressure can be increased.

  With the configuration described above, the brake hydraulic pressure control device 30 supplies the brake hydraulic pressure corresponding to the operating force of the brake pedal BP to each wheel cylinder when all the solenoid valves are in the first state (non-excited state). It can be done. Further, in this state, for example, by controlling the pressure increasing valve PUrr and the pressure reducing valve PDrr, the wheel cylinder fluid is within a range equal to or less than the brake fluid pressure (that is, master cylinder fluid pressure) corresponding to the operating force of the brake pedal BP. Only the pressure Pwrr can be increased, held, and reduced.

  In addition, the brake hydraulic pressure control device 30 switches, for example, the control valve SA1, the switching valve STR, and the pressure increasing valve PUfl to the second state in a state where the brake pedal BP is not operated (opened state). By controlling the pressure increasing valve PUfr and the pressure reducing valve PDfr, the wheel cylinder hydraulic pressure Pacc (high pressure) generated by the high pressure generator 31 while the wheel cylinder hydraulic pressure Pwfl is maintained at “0” is used. Only Pwfr can be controlled to increase pressure, maintain pressure and reduce pressure within the range of accumulator hydraulic pressure Pacc (high pressure).

In this way, the brake hydraulic pressure control device 30 independently controls the wheel cylinder hydraulic pressure of each wheel regardless of the operation of the brake pedal BP, and applies a predetermined braking force independently for each wheel. Be able to. As a result, the brake hydraulic pressure control device 30 can achieve well-known ABS control and automatic pressurization control (oversteer suppression control), which will be described later, according to an instruction from the motion control device 50.

  Referring to FIG. 1 again, the sensor unit 40 includes an electromagnetic pickup type wheel speed sensor 41 ** that outputs a signal having a frequency corresponding to the wheel speed of the wheel **, and an accelerator pedal AP that is operated by the driver. And an accelerator opening sensor 42 that outputs a signal indicating the amount of operation of the accelerator pedal AP (accelerator pedal operation amount Accp), and an ON / OFF signal according to whether the brake pedal BP is operated or not. A brake switch 43 for outputting, a yaw rate sensor 44 for detecting a yaw rate of the vehicle and outputting a signal indicating the yaw rate Yr, a lateral acceleration sensor 45 for detecting a lateral acceleration of the vehicle and outputting a signal indicating the lateral acceleration Gy; The accumulator hydraulic pressure sensor 46 detects the accumulator hydraulic pressure Pacc and outputs a signal indicating the accumulator hydraulic pressure Pacc (see FIG. 2). ) And detects the wheel cylinder hydraulic pressure Pw **, and a wheel-cylinder pressure sensor 47 that outputs a signal indicating the wheel-cylinder pressure Pw ** each ** (see Figure 2).

Note that “**” appended to the end of various variables, etc., indicates “fr”, “fl” appended to the end of the various variables, etc. to indicate to which wheel the various variables are related. For example, the wheel cylinder hydraulic pressure Pw ** is the wheel cylinder hydraulic pressure Pwfr,
Wheel cylinder hydraulic pressure Pwfl, wheel cylinder hydraulic pressure Pwrr, and wheel cylinder hydraulic pressure Pwrl are comprehensively shown.

  Here, the yaw rate Yr and the lateral acceleration Gy are positive values when the vehicle is turning counterclockwise (viewed from above the vehicle), and are negative values when the vehicle is turning clockwise. Is set to take.

The motion control device 50 includes a CPU 51 connected by a bus, a routine (program) executed by the CPU 51, a table (look-up table, map), a ROM 52 in which constants are stored in advance, and the CPU 51 temporarily stores data as necessary. The microcomputer includes a RAM 53 that stores data, a backup RAM 54 that stores data while the power is on, and retains the stored data while the power is shut off, and an interface 55 including an AD converter. The interface 55 is connected to the sensors 41 to 47 and supplies signals from the sensors 41 to 47 to the CPU 51, and the electromagnetic valves and motors M of the brake fluid pressure control device 30 according to instructions from the CPU 51. Drive signals are sent to the throttle valve actuator 22 and the fuel injection device 23.

  Thus, in principle, the throttle valve actuator 22 drives the throttle valve TH so that the throttle valve opening degree TA becomes a value corresponding to the accelerator pedal operation amount Accp, and the fuel injection device 23 An amount of fuel necessary to obtain a predetermined target air-fuel ratio (for example, theoretical air-fuel ratio) is injected with respect to the in-cylinder intake air amount that is the amount of air sucked into the cylinder).

(Overview of OS suppression control)
Next, oversteer suppression control (OS) as automatic pressurization control executed by the brake device 10 (hereinafter referred to as “this device”) including the motion control device according to the first embodiment of the present invention having the above-described configuration. The outline of the suppression control will be described.

  Here, the vehicle body slip angle θ used for the OS suppression control is defined as “an angle formed by the vehicle body direction (that is, the vehicle body longitudinal direction) and the vehicle body traveling direction”. The vehicle body slip angle θ is a positive value when the vehicle body direction is deviated counterclockwise as viewed from above the vehicle with respect to the vehicle traveling direction, and the vehicle body direction is above the vehicle with respect to the vehicle traveling direction. It is assumed that it is set to take a negative value when it is shifted in the clockwise direction when viewed from the side. Then, the vehicle body slip angle θ can be obtained according to the following equation (1). In the following equation (1), Vso is the vehicle speed.

θ = ∫ (Yr− (Gy / Vso)) (1)

  A large absolute value of the vehicle body slip angle θ means that the vehicle is in a so-called “side slip” state (that is, an oversteer state). Therefore, this apparatus performs OS suppression control for suppressing the oversteer state when a predetermined OS suppression control start condition is satisfied, including that the absolute value of the vehicle body slip angle θ is greater than a predetermined value (> 0). Execute.

  Specifically, the present apparatus is configured to change the front wheel on the outer side in the turning direction according to the application pattern of the hydraulic pressure for OS suppression control set based on the absolute value of the vehicle body slip angle θs at the time when the OS suppression control start condition is satisfied. The hydraulic pressure for OS suppression control is forcibly applied to the cylinder W ** independently of the operation of the brake pedal BP (therefore, the braking force corresponding to the hydraulic pressure for OS suppression control is forcibly applied to the front wheel outside the turning direction. To grant). As a result, a yawing moment in the direction opposite to the turning direction is forcibly generated with respect to the vehicle, and the absolute value of the vehicle body slip angle θ is controlled to decrease. As a result, stability in turning of the vehicle can be maintained.

  As the above-mentioned “application pattern of the OS suppression control hydraulic pressure”, for example, the OS suppression control hydraulic pressure is first increased to the maintenance pressure Pt with an increasing gradient Gradup by alternately executing the pressure increase control and the holding control. Subsequently, a pattern is used in which the holding pressure is maintained at the same maintaining pressure Pt for a predetermined time by continuing the holding control, and thereafter decreasing at a predetermined decreasing gradient by alternately executing the pressure reduction control and the holding control.

  Here, the increase gradient Gradup and the maintenance pressure Pt are determined in principle based on the vehicle body slip angle θs when the OS suppression control start condition is satisfied. Specifically, both the increase gradient Gradup and the maintenance pressure Pt are determined to be larger values as the absolute value of the vehicle body slip angle θs at the time when the OS suppression control start condition is satisfied is larger.

  Actually, in this example, the increasing gradient Gradup is expressed by the following equation (2). In the following equation (2), Tup is one duration of the pressure increase control, and Thold is one duration of the holding control. That is, the “combination of Tup and Thold” corresponding to the increasing gradient Gradup is basically determined based on the vehicle body slip angle θs at the time when the OS suppression control start condition is satisfied.

Gradup ＝ Tup / (Tup ＋ Thold)… (2)

  Further, when performing the OS suppression control, the present apparatus, in addition to applying the braking force by applying the OS suppression control hydraulic pressure, controls the output of the engine 21 (specifically, the throttle valve opening TA). Engine output reduction control is executed to reduce the accelerator pedal operation amount Accp by a predetermined amount from a value corresponding to the accelerator pedal operation amount Accp. As a result, the centrifugal force acting on the vehicle decreases as the vehicle body speed decreases, and this also maintains the stability of the vehicle turning. The above is the outline of the OS suppression control.

(Stable ensuring of assisting force for brake operation by hydro booster HB by limiting Gradup for increasing slope of hydraulic pressure for OS suppression control)
As described above, the present apparatus basically determines the increase gradient Gradup (specifically, a combination of Tup and Thold) based on the vehicle body slip angle θs when the OS suppression control start condition is satisfied. However, this apparatus limits the increase gradient Gradup to a certain value (limit value α) or less under a predetermined condition regardless of a value determined based on the vehicle body slip angle θs. This will be described below with reference to FIG.

  FIG. 3 shows the output of the brake switch 43, the accumulator hydraulic pressure Pacc, and the driving of the motor M when the ABS control is executed between the times t1 and t3 and the OS suppression control is started from the time t4 immediately after the end of the ABS control. It is the time chart which showed the change of the state and the fluid pressure for OS suppression control.

  As shown in FIG. 3, before the time t1, the brake pedal BP is not operated (that is, the brake switch 43 outputs an OFF signal), and the accumulator hydraulic pressure Pacc is the lower limit value Pon and the upper limit value. It is assumed that the motor M is in the OFF state during Poff (therefore, the hydraulic pump HP is in the stopped state).

  When the driver starts the operation of the brake pedal BP at time t1 (therefore, the brake switch 43 starts to output an ON signal) and the ABS control is started, the pressure control is performed during the pressure reduction control. The brake fluid is recirculated to the reservoir RS (see FIG. 2) from within the wheel cylinder W ** through the pressure reducing valve PD **.

  As a result, the accumulator hydraulic pressure Pacc is reduced by supplying the brake fluid into the brake hydraulic pressure circuit. As a result, it is assumed that the accumulator hydraulic pressure Pacc becomes less than the lower limit Pon at time t2. In this case, after time t2, the motor M is maintained in the ON state (therefore, the hydraulic pump HP is maintained in the driving state). As a result, when the brake fluid discharge flow rate by the hydraulic pump HP is larger than the average speed at which the brake fluid is recirculated to the brake fluid reservoir RS (that is, the brake fluid consumption speed), the accumulator fluid pressure Pacc immediately increases. Then, it returns to the value that is equal to or higher than the lower limit value Pon.

  On the other hand, in the example shown in FIG. 3, the brake fluid consumption rate is large due to frequent increase / decrease control in the ABS control, and the brake fluid consumption rate is the brake fluid by the hydraulic pump HP. It is assumed that the discharge flow rate is exceeded. In this case, even if the hydraulic pump HP is continuously driven, the accumulator hydraulic pressure Pacc decreases. As a result, it is assumed that the accumulator hydraulic pressure Pacc decreases to the vicinity of the assist limit value Passist at time t3 when the ABS control ends.

  As described above, in the state where the accumulator hydraulic pressure Pacc is reduced to the vicinity of the assist limit value Passist, the OS suppression control is started at time t4 due to the establishment of the OS suppression control start condition. Here, in the example shown in FIG. 3, the vehicle body slip angle θs at the time when the OS suppression control start condition is satisfied (ie, time t4) is relatively large, and as a result, the increase determined based on the vehicle body slip angle θs. It is assumed that the gradient Gradup is set to a relatively large value.

  The broken line shown in FIG. 3 indicates that “the hydraulic pressure application pattern for OS suppression control” and the OS suppression control start when the increasing gradient Gradup is set to the above-described “large value based on the vehicle body slip angle θs”. The change of the accumulator hydraulic pressure Pacc after the time (time t4) is shown. In this case, the OS suppression control ends at time t5.

  As described above, when the increasing gradient Gradup is set to the above-described “large value based on the vehicle body slip angle θs”, the wheel cylinder hydraulic pressure Pw ** of the front wheel on the outer side in the turning direction that is the target of the OS suppression control is increased. Therefore, there is a case where the supply speed of the brake fluid supplied to the wheel cylinder W ** is large, and the supply speed exceeds the brake fluid discharge flow rate by the hydraulic pump HP.

  In this case, as indicated by a broken line in FIG. 3, the accumulator hydraulic pressure Pacc decreases after time t4 even if the hydraulic pump HP is continuously driven. As a result, the accumulator hydraulic pressure Pacc may change below the assist limit value Passist after time t4.

  In such a case, after time t5 when the OS suppression control ends, time before time t7 when the accumulator hydraulic pressure Pacc returns to the assist limit value Passist or higher due to the action of the hydraulic pump HP that is continuously driven. Consider a case where the brake pedal operation by the driver is performed again at t6.

  In this case, the assisting force of the brake pedal operation by the hydro booster HB is sufficient over the period from the time t6 to t7 when the accumulator hydraulic pressure Pacc is less than the assist limit value Passist (see the hatched portion in FIG. 3). Cannot occur (the assist force is insufficient).

  In this apparatus, in order to prevent the occurrence of such a problem, the accumulator hydraulic pressure Pacc at the OS suppression control start time (time t4) is “slightly larger than the assist limit value Passist and sufficiently smaller than the lower limit value Pon. When it is less than the “reference hydraulic pressure Pref” (see FIG. 3), the increase gradient Gradup is limited to a certain limit value α or less.

  More specifically, in this apparatus, the accumulator hydraulic pressure Pacc at the time point when the OS suppression control is started (time t4) is less than the reference hydraulic pressure Pref, and “an increasing gradient determined based on the vehicle body slip angle θs”. When “Gradup” exceeds the limit value α, the increasing gradient Gradup is changed (limited) to a value equal to the limit value α. That is, the Tup and Thold are respectively changed to the value Tuplim and the value Tholdlim that are values corresponding to the limit value α.

  This limit value α is defined as the supply speed of the brake fluid supplied to the wheel cylinder W ** in order to increase the wheel cylinder hydraulic pressure Pw ** of the front wheel on the outer side in the turning direction that is the target of the OS suppression control. The increase gradient Gradup is necessary to make the value slightly smaller than the minimum brake fluid discharge flow rate by the pressure pump HP.

  The solid line shown after time t4 in FIG. 3 indicates the “OS suppression control hydraulic pressure application pattern” when the increase gradient Gradup is limited to the limit value α, and after the OS suppression control start time (time t4). The change of accumulator hydraulic pressure Pacc is shown. In this case, the OS suppression control ends at time t8.

  Thus, when the increase gradient Gradup is limited to the limit value α, the brake supplied to the wheel cylinder W ** in order to increase the wheel cylinder hydraulic pressure Pw ** that is the target of the OS suppression control. The liquid supply speed is always lower than the brake fluid discharge flow rate by the hydraulic pump HP. As a result, it can be ensured that the accumulator hydraulic pressure Pacc always increases while the wheel cylinder hydraulic pressure Pw ** is increased by the OS suppression control.

  Therefore, a situation in which the accumulator hydraulic pressure Pacc becomes less than the assist limit value Passist does not occur after time t8 when the OS suppression control ends. Therefore, even if the driver performs the brake pedal operation again at time t9 after time t8 when the OS suppression control ends, the assisting force of the brake pedal operation by the hydro booster HB can be stably and sufficiently secured.

(Actual operation)
FIG. 4 is a flowchart showing a routine executed by the CPU 51 of the motion control device 50 for the actual operation of the brake device 10 including the motion control device according to the first embodiment of the present invention configured as described above. This will be described with reference to FIG.

  The CPU 51 repeatedly executes the routine for calculating the wheel speed and the like shown in FIG. 4 every elapse of a predetermined time (execution interval time Δt, for example, 6 msec). Therefore, when the predetermined timing is reached, the CPU 51 starts the process from step 400, proceeds to step 405, and calculates the wheel speed (the speed of the outer periphery of the wheel **) Vw ** at the current time of the wheel **. Specifically, the CPU 51 calculates the wheel speed Vw ** based on the fluctuation frequency of the output value of the wheel speed sensor 41 **.

  Next, the CPU 51 proceeds to step 410 to determine whether or not the current accelerator pedal operation amount Accp obtained by the accelerator opening sensor 42 is larger than “0” (that is, whether or not the vehicle is accelerating). ”, The process proceeds to step 415, where the vehicle body speed Vso is set to the minimum value of the wheel speed Vw **. On the other hand, if it is determined“ No ”, the process proceeds to step 420, where the vehicle body speed Vso is set to the wheel speed Vw *. Set to the maximum value of *.

  Subsequently, the CPU 51 proceeds to Step 425, where the current yaw rate Yr obtained from the yaw rate sensor 44, the current lateral acceleration Gy obtained from the lateral acceleration sensor 45, the obtained vehicle body speed Vso, and the above (1). The time differential value dθ of the vehicle body slip angle θ is obtained based on the equation described in step 425 corresponding to the equation, and in the subsequent step 430, the time differential value dθ obtained above and the above-described time differential value dθ are executed. The vehicle body slip angle θ is updated by adding the product of the interval time Δt (that is, the increment of the vehicle body slip angle θ during the execution interval time Δt) (that is, the latest value of the vehicle body slip angle θ is obtained). Then, the CPU 51 proceeds to step 495 and once ends this routine.

  Further, the CPU 51 repeatedly executes a routine for executing the OS suppression control shown in FIG. 5 every elapse of a predetermined time (for example, an execution interval time Δt, for example, 6 msec). Accordingly, when the predetermined timing is reached, the CPU 51 starts processing from step 500 and proceeds to step 505 to determine whether or not the value of the flag OS is “0”. Here, the flag OS indicates that OS suppression control is being executed when the value is “1”, and indicates that OS suppression control is not being executed when the value is “0”.

  The description will be continued assuming that the OS suppression control is not being executed (OS = 0) and the “OS suppression control start condition” described above is not satisfied. In this case, the CPU 51 determines “Yes” in Step 505 and proceeds to Step 510 to determine whether or not the “OS suppression control start condition” described above is satisfied. Immediately proceed to 595 to end the present routine tentatively.

  Thereafter, as long as the “OS suppression control start condition” is not satisfied, the CPU 51 repeatedly executes the processes of steps 505 and 510. As a result, the value of the flag OS is maintained at “0” (see before time t4 in FIG. 3).

  Next, the case where the “OS suppression control start condition” is satisfied in this state (see time t4 in FIG. 3) will be described. In this case, the CPU 51 determines “Yes” when it proceeds to step 510, proceeds to step 515, and changes the value of the flag OS from “0” to “1”.

  Subsequently, the CPU 51 proceeds to step 520 to set the “vehicle body slip angle θs at the time when the OS suppression control start condition is satisfied” to the latest value of the vehicle body slip angle θ updated in the previous step 430. Next, the CPU 51 proceeds to Step 525 and, based on the absolute value of “the vehicle body slip angle θs when the OS suppression control start condition is satisfied”, the “combination of Tup and Thold” corresponding to the increasing gradient Gradup, The maintenance pressure Pt is determined.

  Next, the CPU 51 proceeds to step 530 to determine whether or not the current accumulator fluid pressure Pacc obtained from the accumulator fluid pressure sensor 46 is less than the reference fluid pressure Pref. At 535, it is determined whether or not the “increase gradient Gradup determined based on the vehicle body slip angle θs” expressed by the “combination of Tup and Thold” determined is greater than the limit value α.

  If the determination in step 535 is “Yes” (ie, if Pacc <Pref and “increase gradient Gradup determined based on vehicle body slip angle θs”> α), CPU 51 returns to step 540. Then, Tup and Thold are changed to values Tuplim and Tholdlim, which are values corresponding to the limit value α. That is, the increase gradient Gradup is limited to the limit value α.

  On the other hand, if “No” is determined in step 530 or step 535, the CPU 51 immediately proceeds to step 545 without executing the processing of step 540. Steps 530, 535, and 540 correspond to a limiting unit.

  Subsequently, the CPU 51 proceeds to step 545 to determine an “OS suppression control hydraulic pressure application pattern” from the determined maintenance pressure Pt, the value Tup, and the value Thold, and the wheel cylinder of the front wheel outside the turning direction. A control instruction is issued to the brake hydraulic pressure control device 30 so that the wheel cylinder hydraulic pressure Pw ** obtained by the hydraulic pressure sensor 47 ** changes based on the determined “hydraulic pressure application pattern for OS suppression control”. . This step 545 corresponds to automatic pressurization control means. The turning direction can be determined from the sign of the yaw rate Yr value obtained from the yaw rate sensor 44.

  Then, the CPU 51 proceeds to Step 550 and also executes the engine output reduction control described above for reducing the output of the engine 21 in accordance with the obtained “vehicle body slip angle θs when the OS suppression control start condition is satisfied”. Then, the process proceeds to step 595 to end the present routine tentatively.

  Thereafter, since the value of the flag OS is “1”, the CPU 51 proceeds to step 505 to determine “No” and proceeds to step 555. In step 555, the end condition of the OS suppression control is determined. It is determined whether or not it is established, and if “No” is determined, the process immediately proceeds to step 595 to end the present routine tentatively.

  Thereafter, as long as the OS suppression control termination condition is not satisfied, the CPU 51 repeatedly executes the processes of steps 505 and 555, and during this time, the OS suppression control and the engine output reduction control are continued. During this time, the value of the flag OS is maintained at “1” (see times t4 to t8 in FIG. 3).

  In this state, when the OS suppression control end condition is satisfied (see time t8 in FIG. 3), the CPU 51 determines “Yes” when it proceeds to step 555, proceeds to step 560, and sets the value of the flag OS. “1” is changed to “0”, and the process proceeds to Step 595 to end the present routine tentatively.

  Thereafter, since the value of the flag OS is “0”, the CPU 51 again determines “Yes” in step 505, and monitors again in step 510 whether the OS suppression control start condition is satisfied. To come.

  As described above, the vehicle motion control apparatus according to the first embodiment of the present invention is basically a predetermined high pressure (lower limit value Pon or more, upper limit value) by drive control of the motor M (and hence the hydraulic pump HP). This is applied to a brake device for a vehicle including a hydro booster HB that assists a driver to operate a brake pedal by using an accumulator hydraulic pressure Pacc adjusted to a value Poff or less).

  This motion control device controls a plurality of electromagnetic valves (PUfr, PDfr, STR, SA1, etc.) using the accumulator hydraulic pressure Pacc and executes OS suppression control as automatic pressurization control. The increase gradient Gradup of the brake fluid pressure in the OS suppression control is determined in principle based on the motion state of the vehicle (specifically, the vehicle body slip angle θ). However, the accumulator hydraulic pressure Pacc at the start of the OS suppression control is slightly larger than the lower limit value (that is, assist limit value Passist) of the accumulator hydraulic pressure Pacc necessary for assisting the brake operation by the hydro booster HB and lower than the lower limit value Pon. Is less than a certain reference hydraulic pressure Pref ”, the increase gradient Gradup is limited to a predetermined limit value α or less.

  Thus, it can be guaranteed that the accumulator hydraulic pressure Pacc always increases while the wheel cylinder hydraulic pressure Pw ** is increased by the OS suppression control. As a result, the accumulator hydraulic pressure Pacc after the OS suppression control ends. Is less than the assist limit value Passist. That is, even if the driver performs a brake pedal operation after the OS suppression control is completed, the assist force of the brake pedal operation by the hydro booster HP can be stably and sufficiently secured. As a result, the driver's aim for the brake operation can be ensured. It is possible to ensure a stable deceleration.

(Second Embodiment)
Next, a vehicle brake device including a vehicle motion control device according to a second embodiment of the present invention will be described. In this second embodiment, brake-by-wire control is performed using the accumulator hydraulic pressure Pacc instead of using the hydro booster HB that assists the brake operation by the driver using the accumulator hydraulic pressure Pacc. This is mainly different from the first embodiment. The brake-by-wire control is based on the signal output from the brake operation signal output means that outputs a signal (electrical signal) corresponding to the brake operation by the driver (that is, by the driver). This is a control that generates wheel cylinder hydraulic pressure Pw ** (according to the brake operation). Therefore, the following description will focus on such differences. In the description according to the second embodiment, the same reference numerals, symbols, etc. used in the first embodiment are used for the same or corresponding configurations and variables used in the description according to the first embodiment. Use the same as.

  FIG. 6 shows a schematic configuration of the brake fluid pressure control device 30 according to the second embodiment. As is clear from the comparison with the brake hydraulic pressure control device 30 according to the first embodiment shown in FIG. 2, the brake hydraulic pressure control device 30 according to the second embodiment is such that the brake pedal BP does not pass through the hydro booster HB. Are connected directly to the master cylinder MC, the control valve SA3 is omitted, and a 2-port 2-position switching type is connected to a branch pipe branched from the middle of the pipe connecting the master cylinder MC and the control valve SA1. A known stroke simulator SS is provided via a control valve SA4 which is a normally closed electromagnetic on-off valve, and a stroke sensor 48 which detects an operation stroke of the brake pedal BP and outputs a signal indicating the operation stroke St. The brake fluid pressure control device 30 according to the first embodiment is different from the brake fluid pressure control device 30 in that a brake operation signal output unit is provided.

  By arranging the stroke simulator SS in this way, when the control valve SA1 and the control valve SA2 (and the switching valve STR) are in the excited state, the control valve SA4 is also in the excited state, so that the brake pedal The operation of the BP can be ensured.

  In the normal state, the brake fluid pressure control device 30 according to the second embodiment is configured to always maintain the control valves SA1, SA2, SA4 and the switching valve STR in an excited state. The brake hydraulic pressure control device 30 according to the second embodiment is based on the operation stroke St of the brake pedal BP obtained from the stroke sensor 48 and corresponds to the operation stroke St (that is, according to the brake operation by the driver). The wheel cylinder hydraulic pressure is determined. The brake hydraulic pressure control device 30 according to the second embodiment controls the pressure increasing valve PU ** and the pressure reducing valve PD ** by using the accumulator hydraulic pressure Pacc, so that the wheel cylinder hydraulic pressure Pw ** Control is made so as to match the determined target wheel cylinder hydraulic pressure.

  That is, in a normal state, the brake hydraulic pressure control device 30 according to the second embodiment generates wheel cylinder hydraulic pressure Pw ** according to the brake operation by the driver by so-called brake-by-wire control. ing.

  In addition, the brake hydraulic pressure control device 30 according to the second embodiment is similar to the brake hydraulic pressure control device 30 according to the first embodiment, regardless of the operation stroke St of the brake pedal BP, and the wheel cylinder hydraulic pressure Pw **. Can be freely controlled independently of each other. As a result, the brake fluid pressure control device 30 according to the second embodiment can also achieve the same automatic pressurization control (OS suppression control) as that of the first embodiment.

  On the other hand, when some abnormality occurs, the brake fluid pressure control device 30 according to the second embodiment is configured to put all the solenoid valves in a non-excited state. Thereby, the wheel cylinder hydraulic pressure Pw ** corresponding to the operating force itself of the brake pedal BP can be generated. Thereby, the fail safe function with respect to brake operation can be achieved.

(Stable ensuring of the target wheel cylinder hydraulic pressure Pw ** by limiting the increase gradient Gradup of the hydraulic pressure for OS suppression control)
In the brake-by-wire control described above, the wheel cylinder hydraulic pressure Pw ** exceeding the accumulator hydraulic pressure Pacc cannot be generated. Therefore, if the target wheel cylinder hydraulic pressure corresponding to the maximum brake operation assumed by the driver is called the “normal hydraulic pressure upper limit value Pupper”, the accumulator hydraulic pressure Pacc falls below the normal hydraulic pressure upper limit value Pupper. When the brake operation close to the maximum brake operation is performed, the wheel cylinder hydraulic pressure Pw ** cannot increase to the target wheel cylinder hydraulic pressure with respect to the operation stroke St. As a result, a situation in which the target deceleration for the brake operation cannot be obtained may occur. The normal hydraulic pressure upper limit value Pupper is a value sufficiently smaller than the above-described lower limit value Pon.

  As described above, the situation where the brake operation is performed in a state where the accumulator hydraulic pressure Pacc is lower than the normal hydraulic pressure upper limit value Pupper can occur in the same situation as described with reference to FIG.

  FIG. 7 is a time chart corresponding to FIG. 3, and times t1 to t9 (excluding t7) in FIG. 7 correspond to times t1 to t9 (excluding t7) in FIG. At time t7 in FIG. 7, the accumulator hydraulic pressure Pacc (refer to the broken line) has changed below the normal hydraulic pressure upper limit value Pupper after time t4 when the OS suppression control (see the broken line) with relatively large increase gradient Gradup is started. ) Is the time to return to the normal hydraulic pressure upper limit value Pupper or higher.

  In such a case, a case is considered in which the driver performs a brake operation close to the maximum brake operation at time t6 before time t7 when the accumulator hydraulic pressure Pacc returns to the normal hydraulic pressure upper limit value Pupper or higher.

  In this case, the accumulator hydraulic pressure Pacc is less than the normal hydraulic pressure upper limit value Pupper until the target wheel cylinder hydraulic pressure with respect to the operation stroke St over a period of time t6 to t7 (refer to the shaded portion in FIG. 7). There may be a problem that the wheel cylinder hydraulic pressure Pw ** cannot increase (the brake hydraulic pressure is insufficient).

  In the second embodiment, in order to prevent the occurrence of such a problem, the accumulator hydraulic pressure Pacc at the OS suppression control start time (time t4) is “slightly larger than the normal hydraulic pressure upper limit value Pupper and sufficiently higher than the lower limit value Pon. When the pressure is less than a certain reference hydraulic pressure Pref (see FIG. 7), the increase gradient Gradup is limited to the limit value α or less as in the first embodiment.

  The solid line shown after time t4 in FIG. 7 is similar to the solid line shown after time t4 in FIG. 3, and “the application pattern of the hydraulic pressure for OS suppression control” when the increase gradient Gradup is limited to the limit value α. And the change of the accumulator hydraulic pressure Pacc after the OS suppression control start time (time t4) is shown. In this case, the OS suppression control ends at time t8.

  By limiting the increase gradient Gradup to the limit value α in this way, a situation in which the accumulator hydraulic pressure Pacc becomes less than the normal hydraulic pressure upper limit value Pupper after time t8 when the OS suppression control ends (almost) does not occur. Therefore, even if the driver performs a brake operation close to the maximum brake operation at time t9 after time t8 when the OS suppression control ends, the wheel cylinder hydraulic pressure Pw ** remains at the target wheel cylinder hydraulic pressure with respect to the operation stroke St. The wheel cylinder hydraulic pressure Pw ** targeted for the brake operation can be stably secured.

(Actual operation in the second embodiment)
Hereinafter, an actual operation of the vehicle brake device including the vehicle motion control device according to the second embodiment will be described. The CPU 51 of the second embodiment executes the routines shown in FIGS. 4 and 5 executed by the CPU 51 of the first embodiment as they are.

  If the OS suppression control end condition in step 555 is established, the CPU 51 issues a brake-by-wire control instruction to the brake hydraulic pressure control device 30 by executing a routine (step) (not shown). As a result, as described above, the control valves SA1, SA2, SA4 and the switching valve STR are maintained in the excited state. In addition, the wheel cylinder hydraulic pressure Pw ** is determined according to the operation stroke St by controlling the pressure increasing valve PU ** and the pressure reducing valve PD ** using the accumulator hydraulic pressure Pacc. It is controlled to match.

  As described above, the vehicle motion control apparatus according to the second embodiment of the present invention is basically provided with a predetermined high pressure (lower limit value Pon or more, upper limit value) by drive control of the motor M (and hence the hydraulic pump HP). This is applied to a brake device of a vehicle in which so-called brake-by-wire control is performed using an accumulator hydraulic pressure Pacc adjusted to a value Poff or less).

  Similar to the first embodiment, this motion control device executes OS suppression control as automatic pressurization control. The increase gradient Gradup of the brake fluid pressure in the OS suppression control is determined in principle based on the motion state of the vehicle (specifically, the vehicle body slip angle θ). However, the accumulator hydraulic pressure Pacc at the start of the OS suppression control is slightly larger than the upper limit value of the wheel cylinder hydraulic pressure range necessary for executing the brake-by-wire control (that is, the normal hydraulic pressure upper limit value Pupper), and When it is less than a certain reference hydraulic pressure Pref that is sufficiently smaller than the lower limit value Pon, the increase gradient Gradup is limited to a predetermined limit value α or less.

  Thus, it can be guaranteed that the accumulator hydraulic pressure Pacc always increases while the wheel cylinder hydraulic pressure Pw ** is increased by the OS suppression control. As a result, the accumulator hydraulic pressure Pacc after the OS suppression control ends. Is less than the normal hydraulic pressure upper limit value Pupper. That is, even if the brake pedal operation by the driver is performed after the OS suppression control is completed, the wheel cylinder hydraulic pressure Pw ** targeted for the brake operation can be stably secured. The target deceleration can be secured stably.

  The present invention is not limited to the first and second embodiments, and various modifications can be employed within the scope of the present invention. For example, in the first and second embodiments, the limit value α of the increasing gradient Gradup is a constant value, but the vehicle condition (for example, a factor that affects the brake fluid discharge flow rate by the hydraulic pump HP). The limit value α may be changed according to the brake fluid temperature or the like. In this case, for example, the limit value α is set to a larger value as the temperature of the brake fluid is higher.

  Further, in the first and second embodiments, the brake in the OS suppression control is caused by the use of the pressure increasing valve PU ** and the pressure reducing valve PD ** which are electromagnetic on-off valves as pressure adjusting means. The value “Tup / (Tup + Thold)” (see equation (2) above) is used as the fluid pressure increase gradient Gradup, but a linear solenoid valve that can increase the brake fluid pressure linearly is used as the pressure regulator. In this case, the increasing speed of the brake fluid pressure (increasing speed with respect to time) itself may be used as the increasing gradient Gradup.

  In the first and second embodiments, OS suppression control is executed as automatic pressurization control. However, control such as rollover prevention control, understeer suppression control, inter-vehicle distance control, and traction control is performed by automatic pressurization control. May be executed as

DESCRIPTION OF SYMBOLS 10 ... Brake apparatus including vehicle motion control apparatus, 30 ... Brake hydraulic pressure control apparatus, 41 ** ... Wheel speed sensor, 43 ... Brake switch, 44 ... Yaw rate sensor, 45 ... Lateral acceleration sensor, 46 ... Accumulator hydraulic pressure sensor 47 ... Wheel cylinder hydraulic pressure sensor, 48 ... Stroke sensor, 50 ... Motion controller, 51 ... CPU, Acc ... Accumulator, HP ... Hydraulic pump, M ... Motor, HB ... Hydro booster, PU ** ... Booster valve, PD ** ... Pressure reducing valve, SS ... Stroke simulator

Claims (6)

A hydraulic pump (HP);
Drive control means (M, 51) for driving the hydraulic pump;
An accumulator (Acc) for storing the brake fluid discharged to the accumulator (Acc) by driving of the hydraulic pump by the drive control means and increased in pressure;
Pressure adjusting means (PUfr, PDfr, STR, SA1, etc.) for adjusting the wheel cylinder hydraulic pressure, which is the brake hydraulic pressure in the wheel cylinder,
Detection means (46) for detecting the accumulator hydraulic pressure;
Brake operation signal output means (48) for detecting a brake operation by the driver and outputting a signal corresponding to the brake operation;
Applied to the brake device of a vehicle with
The wheel cylinder hydraulic pressure according to the signal output from the brake operation signal output means (48) by controlling the pressure adjusting means using the accumulator hydraulic pressure that is the pressure of the brake fluid stored in the accumulator. Brake control means (51) for performing brake-by-wire control for generating
An automatic pressurization control for generating the wheel cylinder hydraulic pressure for controlling the movement of the vehicle independently of the brake operation by the driver by controlling the pressure adjusting means using the accumulator hydraulic pressure. Automatic pressure control means (51, 545) to perform;
A vehicle motion control device comprising:
Limiting means (51, 530, 535, 540) is further provided for limiting the degree of increase in the wheel cylinder hydraulic pressure generated by the automatic pressurization control when the detected accumulator hydraulic pressure is less than a predetermined hydraulic pressure. Vehicle motion control device. The vehicle motion control device according to claim 1 ,
The drive control means includes
The hydraulic pump is driven when the detected accumulator hydraulic pressure becomes less than a predetermined lower limit, and the hydraulic pump is driven when the accumulator hydraulic pressure exceeds a predetermined upper limit greater than the lower limit. Is configured to stop
The limiting means is
Vehicle configured to use a value smaller than the lower limit value and larger than an upper limit value of the range of the wheel cylinder hydraulic pressure necessary for execution of the brake-by-wire control as the predetermined hydraulic pressure Motion control device. A hydraulic pump (HP);
Drive control means (M, 51) for driving the hydraulic pump;
An accumulator (Acc) for storing the brake fluid discharged to the accumulator (Acc) by driving of the hydraulic pump by the drive control means and increased in pressure;
Pressure adjusting means (PUfr, PDfr, STR, SA1, etc.) for adjusting the wheel cylinder hydraulic pressure, which is the brake hydraulic pressure in the wheel cylinder,
Detection means (46) for detecting the accumulator hydraulic pressure;
Brake operation signal output means (48) for detecting a brake operation by the driver and outputting a signal corresponding to the brake operation;
Applied to the brake device of a vehicle with
The wheel cylinder hydraulic pressure according to the signal output from the brake operation signal output means (48) by controlling the pressure adjusting means using the accumulator hydraulic pressure that is the pressure of the brake fluid stored in the accumulator. Brake control step for performing brake-by-wire control to generate
An automatic pressurization control for generating the wheel cylinder hydraulic pressure for controlling the movement of the vehicle independently of the brake operation by the driver by controlling the pressure adjusting means using the accumulator hydraulic pressure. An automatic pressurization control step (545) to be performed;
A vehicle motion control program comprising:
A vehicle further comprising a limiting step (530, 535, 540) for limiting an increase in the wheel cylinder hydraulic pressure generated by the automatic pressurization control when the detected accumulator hydraulic pressure is less than a predetermined hydraulic pressure. A program for controlling the movement of a person A hydraulic pump (HP);
Drive control means (M, 51) for driving the hydraulic pump;
An accumulator (Acc) for storing the brake fluid discharged to the accumulator (Acc) by driving of the hydraulic pump by the drive control means and increased in pressure;
Pressure adjusting means (PUfr, PDfr, STR, SA1, etc.) for adjusting the wheel cylinder hydraulic pressure, which is the brake hydraulic pressure in the wheel cylinder,
Detection means (46) for detecting the accumulator hydraulic pressure;
Brake operation signal output means (48) for detecting a brake operation by the driver and outputting a signal corresponding to the brake operation;
Equipped with a,
The drive control means includes
The hydraulic pump is driven when the detected accumulator hydraulic pressure becomes less than a predetermined lower limit, and the hydraulic pump is driven when the accumulator hydraulic pressure exceeds a predetermined upper limit greater than the lower limit. Applied to the brake device of a vehicle configured to stop
The wheel cylinder hydraulic pressure according to the signal output from the brake operation signal output means (48) by controlling the pressure adjusting means using the accumulator hydraulic pressure that is the pressure of the brake fluid stored in the accumulator. Brake control means (51) for performing brake-by-wire control for generating
An automatic pressurization control for generating the wheel cylinder hydraulic pressure for controlling the movement of the vehicle independently of the brake operation by the driver by controlling the pressure adjusting means using the accumulator hydraulic pressure. Automatic pressure control means (51, 545) to perform;
A vehicle motion control device comprising:
Based on the fact that the detected accumulator hydraulic pressure is less than a predetermined hydraulic pressure, an increase gradient of the wheel cylinder hydraulic pressure when the wheel cylinder hydraulic pressure is increased by the automatic pressurization control is transmitted to the wheel cylinder. The vehicle further comprises limiting means (51, 530, 535, 540) for limiting the supply flow rate of the brake fluid to a predetermined gradient or less necessary for making the brake fluid supply flow rate smaller than the discharge flow rate of the brake fluid to the accumulator. Motion control device. The vehicle motion control apparatus according to claim 4 ,
Before Symbol limiting means,
Vehicle configured to use a value smaller than the lower limit value and larger than an upper limit value of the range of the wheel cylinder hydraulic pressure necessary for execution of the brake-by-wire control as the predetermined hydraulic pressure Motion control device. A hydraulic pump (HP);
Drive control means (M, 51) for driving the hydraulic pump;
An accumulator (Acc) for storing the brake fluid discharged to the accumulator (Acc) by driving of the hydraulic pump by the drive control means and increased in pressure;
Pressure adjusting means (PUfr, PDfr, STR, SA1, etc.) for adjusting the wheel cylinder hydraulic pressure, which is the brake hydraulic pressure in the wheel cylinder,
Detection means (46) for detecting the accumulator hydraulic pressure;
Brake operation signal output means (48) for detecting a brake operation by the driver and outputting a signal corresponding to the brake operation;
Equipped with a,
The drive control means includes
The hydraulic pump is driven when the detected accumulator hydraulic pressure becomes less than a predetermined lower limit, and the hydraulic pump is driven when the accumulator hydraulic pressure exceeds a predetermined upper limit greater than the lower limit. Applied to the brake device of a vehicle configured to stop
The wheel cylinder hydraulic pressure according to the signal output from the brake operation signal output means (48) by controlling the pressure adjusting means using the accumulator hydraulic pressure that is the pressure of the brake fluid stored in the accumulator. Brake control step for performing brake-by-wire control to generate
An automatic pressurization control for generating the wheel cylinder hydraulic pressure for controlling the movement of the vehicle independently of the brake operation by the driver by controlling the pressure adjusting means using the accumulator hydraulic pressure. An automatic pressurization control step (545) to be performed;
A vehicle motion control program comprising:
Based on the fact that the detected accumulator hydraulic pressure is less than a predetermined hydraulic pressure, an increase gradient of the wheel cylinder hydraulic pressure when the wheel cylinder hydraulic pressure is increased by the automatic pressurization control is transmitted to the wheel cylinder. The vehicle further includes a limiting step (530, 535, 540) for limiting the brake fluid supply flow rate to a predetermined gradient or less necessary to make the brake fluid supply flow rate smaller than the brake fluid discharge flow rate to the accumulator by the hydraulic pump. Control program.

Images