JP4602186B2 - Brake hydraulic pressure control device for vehicles - Google Patents

Description

  The present invention relates to a vehicular brake fluid pressure control device, for example, a vehicular brake fluid that can perform suitable braking on a road surface in which the left and right wheels arranged coaxially have different road surface friction coefficients, so-called split road surfaces. The present invention relates to a pressure control device.

  2. Description of the Related Art Conventionally, there is known a vehicle brake hydraulic pressure control device that estimates lateral acceleration (acceleration in the lateral direction of a vehicle) during turning of the vehicle and controls wheel brakes based on the estimated estimated lateral acceleration ( For example, see Patent Document 1).

In this vehicle brake hydraulic pressure control device, the wheel speed difference between the left and right wheels is calculated based on the wheel speed, the estimated vehicle body speed is obtained, and the estimated lateral acceleration is calculated therefrom. According to this vehicle brake hydraulic pressure control apparatus, the estimated lateral acceleration can be detected without using an expensive acceleration sensor because the estimated lateral acceleration is obtained based on the information from the wheel speed.
Japanese Patent Laid-Open No. 9-86377

  By the way, in the conventional vehicle brake fluid pressure control device, the estimated lateral acceleration is calculated on the assumption that the wheel rotates following the ground without slipping. For this reason, on a split road surface where the left and right wheels have different road surface friction coefficients, if one of the left and right wheels does not follow the road surface due to braking and slips, the lateral acceleration appears to be greater than the actual acceleration. Therefore, there is a problem in that a proper brake hydraulic pressure control cannot be performed because a wrong estimated lateral acceleration value is calculated.

  Therefore, in the present invention, a vehicle brake capable of performing suitable brake fluid pressure control by obtaining an estimated lateral acceleration value that is not significantly different from the true lateral acceleration from the left and right wheel speeds even on a split road surface or the like. An object is to provide a hydraulic control device.

The present invention for solving the above problem is a provisional horizontal acceleration calculator for calculating a provisional horizontal acceleration of the vehicle from the wheel speeds of the left and right wheels which are disposed coaxially, the wheels of each wheel of the coaxially disposed horizontally A brake fluid pressure estimation unit that estimates the brake fluid pressure in the brake, and a subtraction amount that obtains a subtraction amount for the estimated lateral acceleration correction based on the brake fluid pressure with the smaller fluid pressure among the estimated brake fluid pressures An acquisition unit, an estimated lateral acceleration calculation unit that calculates an estimated lateral acceleration based on the calculated temporary lateral acceleration , and individually controls the brake pressure of the wheel brakes of the left and right wheels based on the calculated estimated lateral acceleration includes a brake control unit that, the said brake control unit is capable of executing an anti-lock brake control, the estimated lateral acceleration calculating unit, the brake control unit is antilock brake control When a line is a value obtained by subtracting the subtraction amount from the previous estimated lateral acceleration, and the of the values of the provisional horizontal acceleration calculated by the temporary lateral acceleration calculating unit, to the smaller and this estimated lateral acceleration It is characterized by.

According to such a vehicle brake hydraulic pressure control device, the temporary lateral acceleration of the vehicle is calculated from the wheel speeds of the left and right wheels arranged coaxially by the temporary lateral acceleration calculation unit, and is coaxially calculated by the brake hydraulic pressure estimation unit. The brake fluid pressure in the wheel brake of each of the arranged left and right wheels is estimated. The subtraction amount acquisition unit acquires the subtraction amount for the estimated lateral acceleration correction based on the brake fluid pressure with the smaller hydraulic pressure among the estimated brake fluid pressures. In other words, for example, when brake fluid pressure control or the like works during brake control on a split road surface, and there is a difference between the estimated brake fluid pressures in the left and right wheel brakes, the brake fluid pressure is estimated to be small. From the state of the other wheel (brake hydraulic pressure), a subtraction amount for the estimated lateral acceleration correction is acquired to be reflected in the calculation of the estimated lateral acceleration. The estimated lateral acceleration calculation unit is a value obtained by subtracting the subtraction amount from the previous estimated lateral acceleration and the temporary lateral acceleration calculated by the temporary lateral acceleration calculation unit when the brake control unit is executing the anti-lock brake control. among the values, the smaller the current estimated lateral acceleration, brake control of the wheel brakes is carried out.

  As a result, during brake control such as brake fluid pressure control, the subtraction amount is subtracted from the provisional lateral acceleration even if one of the left and right wheels slips and the estimated lateral acceleration can be calculated larger than the actual one. Brake control is performed based on the estimated lateral acceleration.

According to such a vehicular brake hydraulic pressure control device, the provisional horizontal estimated lateral acceleration calculating unit during brake control, was calculated value obtained by subtracting a subtraction amount from the previous estimated lateral acceleration, and the Kariyoko acceleration calculation unit The smaller one of the acceleration values is the current estimated lateral acceleration, so even if the estimated lateral acceleration is larger than the temporary estimated lateral acceleration for some reason, Therefore, the estimated lateral acceleration of this time will be calculated.

Further, according to the present invention, the subtraction amount acquisition unit has a predetermined relationship such that when the estimated brake fluid pressure becomes smaller than a predetermined value, the subtraction amount increases as the estimated brake fluid pressure becomes smaller than the predetermined value. Based on this, the subtraction amount is determined.

  According to such a vehicle brake fluid pressure control device, the subtraction amount is determined when the estimated brake fluid pressure becomes smaller than a predetermined value. Therefore, the vehicle is based on the estimated brake fluid pressure. It is possible to determine whether or not the vehicle is traveling on a split road surface (low μ road) and to determine a subtraction amount when it is determined that the vehicle is traveling on a split road surface.

  In addition, the subtraction amount is determined based on a predetermined relationship so that the subtraction amount increases as the brake fluid pressure becomes smaller than a predetermined value. It is possible to calculate an estimated lateral acceleration that is not significantly different from the acceleration.

Further, the present invention is characterized in that the brake fluid pressure estimation unit estimates a brake fluid pressure of the wheel brake on at least a front wheel side.

  According to such a brake fluid pressure control device for a vehicle, since the brake fluid pressure of the wheel brake is estimated mainly on the front wheel side where the road surface condition is likely to appear during brake control, a more reliable lateral acceleration subtraction amount is obtained. Thus, it is possible to perform suitable brake control in accordance with the road surface condition.

Furthermore, the present invention includes a temporary lateral acceleration calculating unit for calculating a provisional horizontal acceleration of the vehicle from the wheel speeds of the left and right wheels which are disposed coaxially, the brake fluid in the wheel brakes of the left and right wheels disposed on said coaxial A brake fluid pressure estimating unit that estimates pressure, a subtraction amount obtaining unit that obtains a subtraction amount for estimated lateral acceleration correction based on the brake fluid pressure of the smaller one of the estimated brake fluid pressures, An estimated lateral acceleration calculation unit that obtains an estimated lateral acceleration by subtracting the subtraction amount from the calculated temporary lateral acceleration, and individually controls the brake pressure of the wheel brakes of the left and right wheels based on the obtained estimated lateral acceleration. includes a brake control unit, wherein the brake controller is capable of executing an anti-lock brake control, the estimated lateral acceleration calculating unit, the brake control unit executes the anti-lock brake control When in, characterized in that is adapted to calculate the estimated lateral acceleration.

According to such a vehicle brake hydraulic pressure control device, the temporary lateral acceleration of the vehicle is calculated from the wheel speeds of the left and right wheels arranged coaxially by the temporary lateral acceleration calculation unit, and is coaxially calculated by the brake hydraulic pressure estimation unit. The brake fluid pressure in the wheel brake of each of the arranged left and right wheels is estimated. The subtraction amount acquisition unit acquires the subtraction amount for the estimated lateral acceleration correction based on the brake fluid pressure with the smaller hydraulic pressure among the estimated brake fluid pressures. In other words, for example, when brake fluid pressure control or the like works during brake control on a split road surface, and there is a difference between the estimated brake fluid pressures in the left and right wheel brakes, the brake fluid pressure is estimated to be small. From the state of the other wheel (brake hydraulic pressure), a subtraction amount for the estimated lateral acceleration correction is acquired to be reflected in the calculation of the estimated lateral acceleration. The estimated lateral acceleration calculation unit calculates the estimated lateral acceleration when the brake control unit is executing antilock brake control, and performs brake control of the wheel brake.

  As a result, during brake control such as brake fluid pressure control, the subtraction amount is subtracted from the provisional lateral acceleration even if one of the left and right wheels slips and the estimated lateral acceleration can be calculated larger than the actual one. Brake control is performed based on the estimated lateral acceleration.

Further, according to the present invention, the subtraction amount acquisition unit accumulates the acquired subtraction amount, and the estimated lateral acceleration calculation unit accumulates the temporary lateral acceleration calculated by the temporary lateral acceleration calculation unit. The estimated lateral acceleration is calculated by subtracting the subtraction amount.

  According to such a vehicle brake hydraulic pressure control device, the subtraction amount acquisition unit accumulates the acquired subtraction amount, and the estimated lateral acceleration calculation unit subtracts the subtraction amount accumulated from the temporary lateral acceleration. Therefore, the estimated lateral acceleration of this time is further calculated based on the previous estimated lateral acceleration at the time of brake control performed last time, and the estimated lateral acceleration that does not greatly differ from the true lateral acceleration is calculated. Acceleration can be calculated.

  According to the present invention, even on a split road surface or the like, a vehicle brake capable of obtaining a value of an estimated lateral acceleration that is not significantly different from a true lateral acceleration from left and right wheel speeds and performing a suitable brake fluid pressure control. A hydraulic control device is obtained.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 1 is a configuration diagram showing a brake system of a vehicle provided with a vehicle brake hydraulic pressure control device according to an embodiment of the present invention, and FIG. 2 is a hydraulic circuit diagram of a hydraulic unit.

As shown in FIG. 1, the vehicle brake fluid pressure control device 100 is for appropriately controlling the braking force (brake fluid pressure) applied to each wheel T of the vehicle CR, and is provided with an oil passage and various parts. The hydraulic unit 10 and the control device 20 for appropriately controlling various components in the hydraulic unit 10 are mainly provided. Further, a wheel speed sensor 30 for detecting the wheel speed of each wheel T of the vehicle CR, specifically, the rotational speed of the wheel T, is connected to the control device 20 of the vehicle brake hydraulic pressure control device 100. . The vehicle CR will be described as a front wheel drive vehicle in which the front wheel side is a drive wheel.
The brake hydraulic pressure output from the hydraulic unit 10 is supplied to a wheel cylinder H provided on each wheel T via a pipe, and is provided on each wheel T via each wheel cylinder H. The brake fluid pressure is applied to the wheel brakes FL, RR, RL, FR.
Further, the control device 20 includes, for example, a CPU, a RAM, a ROM, and an input / output circuit, and performs various arithmetic processes based on the input from each wheel speed sensor 30 and the programs and data stored in the ROM. The control is executed by The wheel cylinder H is a fluid that converts the brake fluid pressure generated by the master cylinder M and the vehicle brake fluid pressure control device 100 into the operating force of the wheel brakes FL, RR, RL, FR provided on each wheel T. Each of which is connected to the hydraulic unit 10 of the vehicle brake hydraulic pressure control device 100 via a pipe.

  The wheel speed sensor 30 is a sensor that detects the wheel speed of each wheel T, and one wheel speed sensor 30 is provided for each wheel T. Each wheel speed sensor 30 is connected to the control device 20 as described above, whereby the control device 20 can acquire all wheel speeds of the four wheels (four wheels) T.

  As shown in FIG. 2, the vehicular brake fluid pressure control device 100 includes a master cylinder M that generates brake fluid pressure corresponding to the pedaling force applied by the driver to the brake pedal P, wheel brakes FL, RR, RL, and FR. It is arranged between. The two output ports M1 and M2 of the master cylinder M are connected to the inlet port 121 of the pump body 10a which is the base body, and the outlet port 122 of the pump body 10a is connected to each wheel brake FL, RR, RL and FR. Yes. In normal times, an oil passage is formed from the inlet port 121 to the outlet port 122 in the vehicle brake fluid pressure control device 100 so that the pedal force of the brake pedal P is applied to each wheel brake FL, RR, RL, It is transmitted to the FR.

  The vehicle brake hydraulic pressure control device 100 is provided with four inlet valves 1, four outlet valves 2, and four check valves 1a corresponding to the respective wheel brakes FL, RR, RL, FR. In addition, two reservoirs 3, two pumps 4, two dampers 5, and two orifices 5a are provided corresponding to the output hydraulic pressure paths 81 and 82 corresponding to the output ports M1 and M2, respectively. An electric motor 6 for driving is provided.

  The inlet valve 1 is a normally open solenoid valve disposed between each wheel brake FL, RR, RL, FR and the master cylinder M. The inlet valve 1 is normally open to allow the brake hydraulic pressure to be transmitted from the master cylinder M to the wheel brakes FL, RR, RL, FR. Further, the inlet valve 1 is blocked by the control device 20 when the wheel T is about to be locked, thereby cutting off the hydraulic pressure transmitted from the brake pedal P to each wheel brake FL, RR, RL, FR.

  The outlet valve 2 is a normally closed electromagnetic valve disposed between each wheel brake FL, RR, RL, FR and each reservoir 3. Although the outlet valve 2 is normally closed, the brake fluid pressure applied to the wheel brakes FL, RR, RL, FR is changed by being released by the control device 20 when the wheel T is about to be locked. Relief to reservoir 3

  The check valve 1a is connected to each inlet valve 1 in parallel. This check valve 1a is a valve that allows only the flow of brake fluid from each wheel brake FL, RR, RL, FR side to the master cylinder M side, and an inlet valve when the input from the brake pedal P is released. Even when 1 is closed, inflow of brake fluid from each wheel brake FL, RR, RL, FR side to the master cylinder M side is allowed.

The reservoir 3 has a function of absorbing brake fluid that is released when each outlet valve 2 is opened.
The pump 4 has a function of sucking the brake fluid absorbed in the reservoir 3 and returning the brake fluid to the master cylinder M via the damper 5 and the orifice 5a. As a result, the pressure state of each of the output hydraulic pressure paths 81 and 82 reduced by the absorption of the brake hydraulic pressure by the reservoir 3 is recovered.

FIG. 3 is a block configuration diagram of a main part of the vehicle brake hydraulic pressure control apparatus 100 according to the embodiment, and FIG. 4 is a block configuration diagram illustrating details of the lateral acceleration estimation unit.
As shown in FIG. 3, the control device 20 opens and closes each inlet valve 1 and outlet valve 2 (see FIG. 2) in the hydraulic unit 10 based on the rotational speed of the wheel T detected by each wheel speed sensor 30. To control the operation of each wheel brake FL, RR, RL, FR.
The control device 20 includes a lateral acceleration estimation unit 21 and a brake control unit 24 as functional units. The lateral acceleration estimation unit 21 includes a map storage unit 21A, and the brake control unit 24 includes a target hydraulic pressure setting unit 25 and a valve drive unit 26.

The lateral acceleration estimating unit 21 inputs the wheel speed of the left rear wheel and the wheel speed of the right rear wheel, which are driven wheels, by the wheel speed sensors 30 and 30, and calculates the estimated lateral acceleration of the vehicle CR. As described above, the wheel speed used to calculate the estimated lateral acceleration is that of a driven wheel that has good followability to the road surface, but it is not always necessary. May be used.
As shown in FIG. 4, the lateral acceleration estimation unit 21 includes, as further detailed functional units, a wheel speed calculation unit 21a, a provisional lateral acceleration calculation unit 21b, a master cylinder pressure estimation unit 21c, a brake hydraulic pressure estimation unit 21d, a subtraction amount An acquisition unit 21e and an estimated lateral acceleration calculation unit 21f are provided.

The wheel speed calculation unit 21a multiplies the radius of the wheel T based on the rotational speeds ω _RL and ω _RR of the wheel T output from the wheel speed sensors 30 of the left rear wheel and the right rear wheel, respectively, and the wheel speeds V _L and V _R. Calculate Calculated wheel speed _V L, _{V R} is outputted to the provisional horizontal acceleration calculating unit 21b.

Temporary lateral acceleration calculating unit 21b, by the same method as conventional, to calculate the provisional horizontal acceleration Gy '(n) from the wheel speed _V L, _{V R.} For example, the temporary lateral acceleration Gy ′ (n) is expressed by the following equation Gy ′ (n) = (V _R −V _L ) × (V _R + V _L ) / 2 × TR (1)
Calculate according to Here, TR is the rear wheel tread. In the present specification, (n) following a variable such as Gy ′ indicates the current calculation result, and (n−1) indicates the previous calculation result.

The master cylinder pressure estimation unit 21c estimates the hydraulic pressure of the master cylinder M by a known method. As an estimation method, for example, the rotational speeds ω _RL , ω _RR , ω _FL , and ω _FR output by the wheel speed sensors 30 of the wheels T at the start of braking are input, and these and the decelerations of the front and rear wheels T are input. From the relationship, there is a method of estimating the master cylinder pressure MC based on a map (not shown) created for each road surface friction coefficient. The master cylinder pressure MC may be detected by providing a pressure sensor (not shown) in the oil passage from the master cylinder M, or a stroke sensor (not shown) for detecting the stroke of the brake pedal P is provided. You may make it estimate the master cylinder pressure MC from the map previously linked | related with this stroke sensor.

  The brake fluid pressure estimating unit 21d estimates the brake fluid pressure in the wheel brakes of the left and right wheels T arranged coaxially. In the present embodiment, the brake fluid pressure of the left front wheel and the right front wheel that are drive wheels is estimated. The estimation of the brake fluid pressure differs depending on whether or not the anti-lock brake control is being performed. During the anti-lock brake non-control, the master cylinder pressure MC estimated by the master cylinder pressure estimating unit 21c is used as the brake fluid pressure PCAL (n). Estimate as This is because the brake fluid pressure from the master cylinder M is directly applied to the wheel brakes FL, FR, RL, RR of each wheel T through the fluid passage in the pump body 10a during anti-lock brake non-control. This is because the pressure MC becomes the brake fluid pressure PCAL (n) of the left front wheel and the right front wheel.

Next, during the antilock brake control, the brake fluid pressure estimation method differs depending on whether the brake fluid pressure is controlled to be reduced or increased. First, when the brake fluid pressure is controlled to be reduced, the deviation between the previous brake fluid pressure PCAL (n-1) and zero atmospheric pressure (reduced pressure target value) is multiplied by a coefficient k, and this is used as the previous brake fluid pressure. The brake fluid pressure PCAL (n) is calculated by subtracting from the pressure PCAL (n-1). The brake hydraulic pressure PCAL (n) is expressed by the following formula: PCAL (n) = PCAL (n−1) − (k × (PCAL (n−1) −0)) (2)
It can ask for. Here, the coefficient k is a predetermined value set by the drive time of the inlet valve 1 and the outlet valve 2.

Further, when the brake fluid pressure is controlled to increase, the deviation between the previous brake fluid pressure PCAL (n−1) and the master cylinder pressure MC is multiplied by a coefficient k, and this is multiplied by the previous brake fluid pressure PCAL ( In addition to n-1), the brake fluid pressure PCAL (n) is calculated. The brake fluid pressure PCAL (n) is expressed by the following equation: PCAL (n) = PCAL (n−1) + (k × (MC (n) −PCAL (n−1))) (3)
It can ask for.
The calculated brake hydraulic pressure PCAL (n) at each of the left and right wheels T is output to the subtraction amount acquisition unit 21e.

The subtraction amount acquisition unit 21e specifies the brake hydraulic pressure with the smaller hydraulic pressure among the brake hydraulic pressures on the left and right coaxial wheels T estimated by the brake hydraulic pressure estimation unit 21d, and based on the brake hydraulic pressure. Then, a subtraction amount DecGy for correcting the estimated lateral acceleration is acquired. The subtraction amount DecGy is acquired with reference to the map stored in the map storage unit 21A.
The map stored in the map storage unit 21A is, for example, as shown in FIG. As shown in FIG. 5, the map of the map storage unit 21A is determined such that when the estimated brake fluid pressure becomes smaller than a predetermined value, the subtraction amount DecGy increases as the estimated brake fluid pressure becomes smaller than the predetermined value. .

  The map of FIG. 5 will be described in more detail. When the brake fluid pressure is medium to large, the subtraction amount DecGy is 0 at about 1.5 MPa to 3.0 MPa. Then, the subtraction amount DecGy increases as the brake fluid pressure decreases from about 1.5 MPa. Here, the reason why the subtraction amount is generated on the side where the brake fluid pressure becomes smaller at the boundary of 1.5 MPa is to obtain the subtraction amount when traveling on the split road surface where the brake fluid pressure becomes smaller. The brake fluid pressure and the subtraction amount can be set arbitrarily. In addition, the subtraction amount DecGy increases as the brake fluid pressure becomes smaller than 1.5 MPa. The brake fluid pressure decreases as the brake fluid pressure decreases, that is, the road surface friction coefficient decreases and the split road surface easily slips. Accordingly, the calculation of the provisional lateral acceleration Gy ′ (n) is likely to be erroneously calculated (easily calculated to a value far from the true lateral acceleration). By increasing DecGy, the estimated lateral acceleration Gy (n) can be reduced.

Based on the temporary lateral acceleration Gy ′ (n) calculated by the temporary lateral acceleration calculation unit 21b and the subtraction amount DecGy acquired by the subtraction amount acquisition unit 21e, the estimated lateral acceleration calculation unit 21f To calculate the estimated lateral acceleration (current estimated lateral acceleration) Gy (n). The estimated lateral acceleration Gy (n) is
Gy (n) = min (Gy ′ (n), Gy (n−1) −DecGy (n)) (4)
It can ask for. That is, the estimated lateral acceleration calculation unit 21f during the brake control calculates a value obtained by subtracting the subtraction value DecGy (n) from the previous estimated lateral acceleration Gy (n-1) and the temporary lateral acceleration calculated by the temporary lateral acceleration calculation unit 21b. The smaller value of the acceleration Gy ′ (n) is set as the current estimated lateral acceleration Gy (n). The calculated estimated lateral acceleration Gy (n) is output to the target hydraulic pressure setting unit 25 of the brake control unit 24.

  The target hydraulic pressure setting unit 25 determines the wheel brakes FL, RR, RL, FR based on the estimated lateral acceleration Gy (n) estimated by the lateral acceleration estimating unit 21 and the rotational speed ω of the wheel T detected by the wheel speed sensor 30. Set the target hydraulic pressure. This setting method may be performed by a conventionally known method and is not particularly limited. As an example, the wheel speed V of each wheel T is calculated from the rotational speed ω of the four wheels T, and the vehicle body speed is estimated from the wheel speed V. Then, the slip ratio is calculated from the vehicle body speed and the wheel speed V. Further, based on the estimated lateral acceleration Gy (n) and the front and rear vehicle body acceleration, a combined acceleration is calculated, and a road surface friction coefficient is estimated from the combined acceleration. Based on the friction coefficient, the slip ratio, and the current hydraulic pressure of the wheel cylinder H, the target hydraulic pressures of the wheel brakes FL, RL, FR, and RR can be set.

  The valve drive unit 26 is configured by a conventionally known method so that the hydraulic pressure of the wheel cylinder H of each wheel brake FL, RL, FR, RR matches the target hydraulic pressure set by the target hydraulic pressure setting unit 25. A pulse signal for operating each inlet valve 1 and outlet valve 2 in 10 is output to the hydraulic unit 10. For example, the pulse signal outputs more pulses as the deviation between the current hydraulic pressure of the wheel cylinder H and the target hydraulic pressure increases. Note that the current hydraulic pressure of the wheel cylinder H may be measured by a sensor or may be estimated by calculation.

  The operation of the vehicular brake hydraulic pressure control device 100 will be described with reference to FIGS. 6 and 7. FIG. 6 shows the wheel speed (a) when the antilock brake control is operated on the split road surface, the brake fluid pressure (b) of the wheel on the low μ side, the subtraction amount (c), the provisional lateral acceleration, and the calculated estimated lateral force. FIG. 7 is a timing chart of acceleration (d), and FIG. 7 is a flowchart showing processing of the lateral acceleration estimation unit.

As shown in FIG. 6 (a), if the anti-lock brake control is started during straight braking of the vehicle CR, for example, the wheel speed V _R of the wheel T of high μ side, while Yuku are gradually decelerated, The wheel speed V _L of the wheel T on the low μ side is adjusted for the brake fluid pressure according to the road surface condition (see FIG. 6B), and repeats acceleration and deceleration. Accordingly, a difference in brake fluid pressure occurs between the wheel T on the high μ side and the wheel T on the low μ side, and the brake fluid pressure with the smaller brake fluid pressure, that is, the brake on the wheel T on the low μ side. A subtraction amount DecGy is acquired based on the hydraulic pressure. Then, as shown in FIG. 6D, the acquired subtraction amount DecGy is subtracted from the provisional lateral acceleration Gy ′ (n) to calculate the estimated lateral acceleration Gy (n) (details will be described later). Alternatively this estimated lateral acceleration Gy (n) is estimated by subtraction of subtraction amount DecGy from the previous estimated lateral acceleration Gy (n-1). In any case, as shown by a thick line in FIG. 6D, the calculation result of the estimated lateral acceleration Gy (n) is gradually zero over time while the temporary lateral acceleration Gy ′ (n) repeats fluctuations. As compared with the above, the estimated lateral acceleration Gy (n) is reduced earlier and becomes zero.

Calculation processing of this case, as shown in FIG. 7, first, the wheel speed V _L, the V _R, in the same manner as a conventional calculating temporary lateral acceleration Gy '(n) (S1) , each wheel of the wheel T The master cylinder pressure MC is estimated from the rotational speeds ω _RL , ω _RR , ω _FL , and ω _FR output from the speed sensor 30 (S2). Based on the estimated master cylinder pressure MC, the brake fluid pressure PCAL (n) of the left and right wheels T of the front wheels is estimated (S3). Thereafter, the subtraction amount DecGy is acquired from the map based on the brake fluid pressure PCAL (n) having the smaller fluid pressure among the estimated brake fluid pressure PCAL (n) (S4). Next, the estimated lateral acceleration Gy (n) is calculated by subtracting the subtraction amount DecGy from the temporary lateral acceleration Gy ′ (n) (S5) , or the subtraction amount DecGy from the previous estimated lateral acceleration Gy (n−1). and subtract to calculate the current estimated lateral acceleration Gy (n). In any case, the value of the estimated lateral acceleration Gy (n) decreases early, but further subtracted from it based on the previous estimated lateral acceleration Gy (n−1) as shown in FIG. If the amount DecGy is subtracted the estimated that the change of the current estimated lateral acceleration Gy (n) becomes very small, resulting in calculated estimated lateral acceleration Gy (n) to a large value to a running straight Mistakes are alleviated and close to true lateral acceleration. Also, as shown at time t in FIG. 6 (d), when the provisional lateral acceleration Gy ′ (n) suddenly increases, the subtraction amount DecGy having a large value is acquired from the map. The amount of change in the lateral acceleration Gy (n) can be kept small. Note that the lateral acceleration estimation unit 21 during brake control has a value obtained by subtracting the subtraction value DecGy (n) from the previous estimated lateral acceleration Gy (n−1) and the temporary lateral acceleration calculated by the temporary lateral acceleration calculation unit 21b. Of the values of Gy ′ (n), the smaller one is set as the estimated lateral acceleration Gy (n) of this time (see equation (4)), so the previous lateral acceleration is higher than the value of the temporary lateral acceleration Gy ′ (n) for some reason. Even in a situation where the value obtained by subtracting the subtraction value DecGy (n) from Gy (n−1) is larger, the estimated lateral acceleration is always calculated in the direction in which the value of the estimated lateral acceleration Gy (n) decreases. The Rukoto.

  As described above, according to the vehicle brake hydraulic pressure control device 100 of the present embodiment, on the split road surface, some of the wheels T are likely to lock, and the brake hydraulic pressure PCAL (n ), The subtraction amount DecGy is subtracted from the temporary lateral acceleration Gy ′ (n) based on the brake hydraulic pressure PCAL (n) with the smaller hydraulic pressure, and the estimated lateral acceleration Gy (n). Therefore, the estimated lateral acceleration Gy (n) can be obtained relatively accurately. Therefore, even in the antilock brake control using the estimated lateral acceleration Gy (n), it is possible to accurately predict the situation of the vehicle CR and perform appropriate control.

As mentioned above, although embodiment of this invention was described, this invention is not limited to above-described embodiment, It can implement by changing suitably.
For example, in the above-described embodiment, the subtraction amount DecGy is further subtracted from the previous estimated lateral acceleration Gy (n−1) to obtain the current estimated lateral acceleration Gy (n), but the provisional lateral acceleration Gy ′ ( The current estimated lateral acceleration Gy (n) may be obtained by subtracting the subtraction amount DecGy from n). In this case, the subtraction amount acquisition unit 21e is configured to accumulate the acquired subtraction amount, and subtracts the subtraction amount accumulated from the temporary lateral acceleration Gy ′ (n) to obtain the current estimated lateral acceleration Gy (n). You may comprise so that it may require | require.
Furthermore, the brake fluid pressure can be estimated by estimating the brake fluid pressure of at least the front wheel brakes FL and FR. By configuring in this way, since the brake fluid pressure of the wheel brakes FL and FR is mainly estimated on the front wheel side where the road surface condition is likely to appear during brake control, a highly reliable subtraction amount of the estimated lateral acceleration is obtained. Thereby, suitable brake control according to the road surface condition can be performed.
Further, the lateral acceleration calculation method (apparatus) according to the present invention can be applied not only to antilock brake control but also to other control using lateral acceleration. For example, depending on the estimated lateral acceleration, the braking force of some wheel brakes and engine output are controlled as appropriate to control the posture of the vehicle, the tilt of the vehicle body, the strength of the suspension, etc. May be.
Further, the map is used to obtain the subtraction amount DecGy, but it can also be obtained by a function.

It is a lineblock diagram showing the brake system of vehicles provided with the brake fluid pressure control device for vehicles concerning one embodiment of the present invention. It is a hydraulic circuit diagram of a hydraulic unit. 1 is a block configuration diagram of a vehicle brake hydraulic pressure control device according to an embodiment. FIG. It is a block block diagram which shows the detail of a lateral acceleration estimation part. It is a map which shows the relationship between brake fluid pressure and subtraction amount. Timing chart of wheel speed (a), brake fluid pressure (b), subtraction amount (c), provisional lateral acceleration and estimated lateral acceleration (d) when anti-lock brake control is operated on a split road surface It is. It is a flowchart which shows the process of a lateral acceleration estimation part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hydraulic unit 10a Pump body 11 Hydraulic unit 20 Control apparatus 21 Lateral acceleration estimation part 21A Map memory | storage part 21a Wheel speed calculation part 21b Temporary lateral acceleration calculation part 21c Master cylinder pressure estimation part 21d Brake hydraulic pressure estimation part 21e Acquisition of subtraction amount Unit 21f Estimated lateral acceleration calculation unit 23 Valve drive unit 24 Brake control unit 25 Target hydraulic pressure setting unit 26 Valve drive unit 30 Wheel speed sensor 100 Brake hydraulic pressure control device for vehicle

Claims (5)

A temporary lateral acceleration calculation unit that calculates the temporary lateral acceleration of the vehicle from the wheel speeds of the left and right wheels arranged coaxially ;
A brake fluid pressure estimation section for estimating the brake fluid pressure in the wheel brakes of the left and right wheels disposed on the same axis,
Of the estimated brake fluid pressures, a subtraction amount acquisition unit that acquires a subtraction amount for estimated lateral acceleration correction based on the brake fluid pressure with the smaller fluid pressure;
An estimated lateral acceleration calculation unit that calculates an estimated lateral acceleration based on the calculated temporary lateral acceleration;
A brake control unit that individually controls the brake pressure of the wheel brake of each of the left and right wheels based on the calculated estimated lateral acceleration,
The brake control unit can execute anti-lock brake control,
The estimated lateral acceleration calculation unit is a value obtained by subtracting the subtraction amount from the previous estimated lateral acceleration when the brake control unit is executing anti-lock brake control , and the temporary lateral acceleration calculation unit. A brake fluid pressure control apparatus for a vehicle, characterized in that a smaller one of the lateral acceleration values is set as a current estimated lateral acceleration. The subtraction amount acquisition unit calculates the subtraction amount based on a predetermined relationship so that the subtraction amount increases as the estimated brake fluid pressure becomes smaller than the predetermined value. The vehicular brake hydraulic pressure control device according to claim 1 , wherein the vehicular brake hydraulic pressure control device is defined. The vehicle brake fluid pressure control device according to claim 1 or 2 , wherein the brake fluid pressure estimation unit estimates a brake fluid pressure of at least the wheel brake on the front wheel side. A temporary lateral acceleration calculation unit that calculates the temporary lateral acceleration of the vehicle from the wheel speeds of the left and right wheels arranged coaxially ;
A brake fluid pressure estimation section for estimating the brake fluid pressure in the wheel brakes of the left and right wheels disposed on the same axis,
Of the estimated brake fluid pressures, a subtraction amount acquisition unit that acquires a subtraction amount for estimated lateral acceleration correction based on the brake fluid pressure with the smaller fluid pressure;
An estimated lateral acceleration calculation unit that calculates an estimated lateral acceleration by subtracting the subtraction amount from the calculated temporary lateral acceleration;
A brake control unit that individually controls the brake pressure of the wheel brake of each of the left and right wheels based on the obtained estimated lateral acceleration,
The brake control unit can execute anti-lock brake control,
The estimated lateral acceleration calculation unit is configured to calculate the estimated lateral acceleration when the brake control unit is executing anti-lock brake control . The subtraction amount acquisition unit has the acquired subtraction amount accumulated,
5. The vehicle brake according to claim 4 , wherein the estimated lateral acceleration calculation unit calculates an estimated lateral acceleration by subtracting a cumulative subtraction amount from the temporary lateral acceleration calculated by the temporary lateral acceleration calculation unit. Hydraulic control device.

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