JP4193525B2 - Anti-skid control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an anti-skid control device that controls brake fluid pressure so that each wheel does not lock during vehicle braking, and more particularly to an anti-skid control device that is suitable for a vehicle equipped with a continuously variable transmission in a drive system.
[0002]
[Prior art]
It is known that the gear ratio of the continuously variable transmission is controlled according to the vehicle body speed even during the operation of the anti-skid control device (see Patent Document 1 below). According to this conventional technique, the anti-skid control can be more reliably executed.
[0003]
[Patent Document 1]
JP-A-7-172218 (Pages 5-11, Fig. 1)
[0004]
[Problems to be solved by the invention]
However, the gear ratio during anti-skid control is likely to deviate from an appropriate gear ratio, that is, a gear ratio that matches the actual vehicle speed. This is because during anti-skid control, the wheel speed fluctuates due to increase or decrease in brake fluid pressure, while shift control by a continuously variable transmission is generally executed according to the vehicle speed equivalent to the wheel speed.
[0005]
For example, when the actual gear ratio shifts to the low speed side with respect to the appropriate gear ratio, strong engine braking is applied, so even if the brake fluid pressure is reduced by anti-skid control, recovery of the wheel speed is delayed, Deceleration, vehicle stability and steering are reduced.
[0006]
The present invention has been made to solve the above-described problems. Even when the gear ratio of the continuously variable transmission deviates from an appropriate value during the operation of the anti-skid control device, the deceleration, the vehicle stability are improved. It is an object of the present invention to provide an anti-skid control device capable of suppressing deterioration in performance and steering performance.
[0007]
[Means for Solving the Problems]
An anti-skid control device according to the present invention is an anti-skid control device in a vehicle equipped with a continuously variable transmission whose speed ratio is controlled based on the speed of the vehicle, and detects a slip state of a wheel during vehicle braking. A slip condition detecting means; and a brake fluid pressure control means for controlling the brake fluid pressure of the wheel based on the slip condition. The brake fluid pressure control means has an actual gear ratio and an appropriate gear ratio deviated by a predetermined value or more. In this case, the control value for controlling the brake fluid pressure is corrected.
[0008]
According to the anti-skid control device of the present invention, when the brake hydraulic pressure is controlled by the brake hydraulic pressure control means based on the slip state of the wheel, and the actual gear ratio and the appropriate gear ratio deviate by a predetermined value or more. The control value for controlling the brake fluid pressure is corrected. Therefore, even when the gear ratio of the continuously variable transmission deviates from an appropriate value, it is possible to appropriately perform anti-skid control.
[0009]
The control value is preferably one or both of the brake fluid pressure control start timing and the pressure increase / decrease amount.
[0010]
When the control start time is corrected, an excessive drop in wheel speed can be prevented, and when the pressure increase / decrease amount is corrected, a delay in recovery of the wheel speed can be suppressed.
[0011]
The anti-skid control device according to the present invention sets the estimated vehicle body speed based on the wheel speed, and sets the estimated vehicle body speed setting that limits the change gradient of the estimated vehicle body speed when setting the estimated vehicle body speed. It is preferable that an appropriate gear ratio is provided in accordance with the estimated vehicle body speed.
[0012]
In this case, when the estimated vehicle body speed is set, a limit is imposed on the gradient of the estimated vehicle body speed, so that an accurate vehicle body speed can be obtained even when the wheel speed changes suddenly due to slip. Therefore, by determining the transmission ratio using the estimated vehicle speed, it is possible to determine an appropriate transmission ratio based on a more accurate vehicle speed even during anti-skid control.
[0013]
The anti-skid control device according to the present invention further includes a vehicle body deceleration calculating means for calculating a vehicle body deceleration based on a change amount of the estimated vehicle body speed, and when the vehicle body deceleration is a predetermined value or less, the brake fluid pressure It is preferable that the control means corrects the control value according to the vehicle body deceleration.
[0014]
In this case, the control value for controlling the brake fluid pressure is corrected according to the vehicle body deceleration reflecting the road surface condition on an extremely low μ road where the vehicle body deceleration decreases below a predetermined value. Anti-skid control can be performed.
[0015]
In the anti-skid control device according to the present invention, it is preferable that the estimated vehicle body speed setting unit corrects the limit value of the change gradient according to the gear ratio when the vehicle body deceleration is larger than a predetermined value.
[0016]
If comprised in this way, it will become possible to suppress the rapid change of the estimated vehicle body speed which arises from a wheel speed changing rapidly by engine braking.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
[0018]
First, the overall configuration of the anti-skid control device 1 according to the present embodiment will be described with reference to FIG.
[0019]
The anti-skid control device 1 according to the present embodiment is an anti-skid control device (ABS) with an EBD (Electronic Break Force Distribution), and includes a master cylinder 2a and a booster 2b as a hydraulic pressure generating device. These are driven by the brake pedal 3. Wheel cylinders 51 to 54 are attached to the respective wheels FR, FL, RR, RL. The wheel FR indicates the front right side, the wheel FL indicates the front left side, the wheel RR indicates the rear right side, and the wheel RL indicates the rear left side as viewed from the driver's seat, and so-called diagonal two systems are configured.
[0020]
Normally open solenoid valves 31 and 37 are disposed in the hydraulic pressure passages connecting the one output port of the master cylinder 2a and the wheel cylinders 51 and 54, respectively, and between these and the master cylinder 2a, the hydraulic pump 21 The discharge side is connected. Similarly, normally open solenoid valves 33 and 35 are disposed in hydraulic pressure paths connecting the other output port of the master cylinder 2a and the wheel cylinders 52 and 53, respectively, and hydraulic pressure is provided between them and the master cylinder 2a. The discharge side of the pump 22 is connected.
[0021]
The hydraulic pumps 21 and 22 are driven by the electric motor 20, and brake fluid whose pressure has been increased to a predetermined pressure is supplied to each of the hydraulic pressure paths when operating.
[0022]
The wheel cylinders 51 and 54 are further connected to normally closed electromagnetic valves 32 and 38, and their downstream sides are connected to the reservoir 23 and to the suction side of the hydraulic pump 21. The wheel cylinders 52 and 53 are also connected to normally closed electromagnetic valves 34 and 36, and their downstream sides are connected to the reservoir 24 and to the suction side of the hydraulic pump 22. Each of the reservoirs 23 and 24 includes a piston and a spring, and accommodates brake fluid discharged from each wheel cylinder through the solenoid valves 32, 34, 36 and 38.
[0023]
The electromagnetic valves 31 to 38 are two-port two-position electromagnetic switching valves, which are in the first position shown in FIG. 1 when the solenoid coil is not energized, and each of the wheel cylinders 51 to 54 communicates with the master cylinder 2a. When the solenoid coil is energized, the wheel cylinders 51 to 54 are disconnected from the master cylinder 2 a and communicate with the reservoir 23 or 24. In FIG. 1, DP is a damper, CV is a check valve, OR is an orifice, and FT is a filter. The check valve CV allows the reflux from the wheel cylinders 51 to 54 and the reservoirs 23 and 24 to the master cylinder 2a, and blocks the reverse flow.
[0024]
In this manner, the brake fluid pressure in the wheel cylinders 51 to 54 can be increased, reduced or held by controlling energization and non-energization of the solenoid coils of the electromagnetic valves 31 to 38. That is, when the solenoid coils of the solenoid valves 31 to 38 are not energized, the brake fluid pressure is supplied to the wheel cylinders 51 to 54 from the master cylinder 2a and the hydraulic pump 21 or 22, and the pressure is increased. Alternatively, the pressure is reduced to the 24th side. If the solenoid coils of the solenoid valves 31, 33, 35, and 37 are energized and the solenoid coils of the other solenoid valves are de-energized, the brake fluid pressure in the wheel cylinders 51 to 54 is maintained. Accordingly, it is possible to control so as to increase pressure gently (pulse pressure increase) by adjusting the time interval between energization and non-energization of the solenoid coil.
[0025]
The solenoid valves 31 to 38 are connected to an anti-skid control electronic control device (hereinafter referred to as ABS ECU) 10, and the energization and non-energization of each solenoid coil is controlled by the ABS ECU 10. The electric motor 20 is also connected to the ABS ECU 10 and is driven and controlled by the ABS ECU 10. Each of the wheels FR, FL, RR, and RL is provided with wheel speed sensors 41 to 44, which are connected to the ABS ECU 10, and a rotational speed of each wheel, that is, a signal corresponding to the wheel speed is transmitted to the ABS ECU 10. It is comprised so that it may be input. The ABS ECU 10 is further connected to a brake switch 4 that is turned on when the brake pedal 3 is depressed.
[0026]
The ABS ECU 10 is internally stored with a microprocessor that performs calculations, a ROM that stores a program for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, and a 12V battery. A backup RAM or the like.
[0027]
With the above configuration, the ABS ECU 10 includes a slip state detection unit 10a that detects the slip state of the wheels 51 to 54 based on the wheel speed signal, and the slip states of the wheels FR, FL, RR, and RL. The brake fluid pressure control unit 10b for adjusting the brake fluid pressure in the wheel cylinders 51 to 54, the estimated vehicle body speed setting unit 10c for setting the estimated vehicle body speed VSO using the wheel speed signal, and the vehicle body based on the estimated vehicle body speed VSO A vehicle body deceleration calculation unit 10d for calculating the deceleration is constructed. That is, the ABS ECU 10 functions as slip state detection means, brake fluid pressure control means, estimated vehicle body speed setting means, and vehicle body deceleration calculation means.
[0028]
Note that the ABS ECU 10 and a later-described continuously variable transmission electronic control unit (hereinafter referred to as CVT ECU) 80 are connected by a communication line 12, and are configured to be able to exchange information with each other. The ABS ECU 10 receives transmission ratio information of a continuously variable transmission (hereinafter referred to as CVT) 70 transmitted from the CVT ECU 80 via the communication line 12, and also anti-skid control (hereinafter referred to as ABS control). Is transmitted to the CVT ECU 80.
[0029]
By having the above configuration, the anti-skid control device 1 prevents locking of the wheels FR, FL, RR, RL, and in addition to anti-skid control for ensuring braking performance, regardless of load changes due to empty vehicles / loading, etc. In addition, it is possible to execute braking force distribution control (EBD control) for distributing the braking force of each wheel so that the braking forces of the front and rear wheels and the left and right wheels are appropriately controlled.
[0030]
Subsequently, a power transmission mechanism of the CVT 70 in the vehicle on which the anti-skid control device 1 according to the present embodiment is mounted will be described with reference to FIG.
[0031]
The CVT 70 includes a primary pulley DR having a variable effective diameter provided on the input shaft 72, a secondary pulley DN having a variable effective diameter provided on the output shaft 74, and a metal wound around these variable pulleys DR and DN. A belt BT is provided, and power is transmitted through a frictional force between the variable pulleys DR and DN and the metal belt BT. Each of the variable pulleys DR and DN has a variable V-groove width and is configured to include a hydraulic cylinder. When the hydraulic pressure of the hydraulic cylinder of the primary pulley DR is controlled by the CVT ECU 80, the variable pulleys DR and DN The V-groove width is changed to change the engagement diameter (effective diameter) of the metal belt BT, and the gear ratio (= input shaft rotational speed / output shaft rotational speed) is continuously changed.
[0032]
The output of the engine is transmitted from the torque converter 100 to the differential gear device 130 via the forward / reverse switching device 110, the CVT 70, and the reduction gear 120, and is distributed to the left and right wheels FR, FL.
[0033]
The CVT ECU 80 includes wheel speed sensors 41 and 42 for detecting the wheel speeds of the left and right front wheels FR and FL, an output shaft rotational speed sensor 90 for detecting the output shaft rotational speed, and an input shaft rotational speed sensor 91 for detecting the input shaft rotational speed. An engine speed sensor 92 that detects the engine speed and an accelerator position sensor 93 that detects the accelerator position are connected. Also, the CVT ECU 80 receives information regarding whether or not ABS / EBD control is being executed from the ABS ECU 10 via the communication line 12.
[0034]
The CVT ECU 80 is configured to include a microprocessor that performs calculation, and performs a shift control, a narrow pressure control, and the like of the CVT 70 by performing signal processing according to a program stored in advance in the ROM.
[0035]
The CVT ECU 80 includes a shift control unit 80a that performs shift control therein. The shift control unit 80a calculates the target rotational speed on the input side from a predetermined shift map using the vehicle speed and the accelerator opening obtained from the average values of the wheel speeds of the left and right front wheels FR and FL as parameters, The gear ratio of the CVT 70 is controlled so that the shaft rotational speed matches the target rotational speed. Specifically, the gear ratio is controlled by controlling the supply and discharge of hydraulic oil to and from the hydraulic cylinder of the primary pulley DR.
[0036]
Next, the operation of the anti-skid control device 1 according to this embodiment will be described with reference to FIGS. First, the control start time change process, the pressure increase / decrease amount change process, and the estimated vehicle body speed change gradient limit value correction process of the ABS / EBD control will be described with reference to FIG.
[0037]
In step S100, a determination is made as to whether or not the transmission ratio information of the CVT 70 received via the communication line 12 is valid based on the communication error information or the like. If it is determined that the received information is not valid, the process proceeds to step S101, and normal ABS / EBD control that does not use the gear ratio information of the CVT 70 is executed. On the other hand, if it is determined that the received information is valid, the process proceeds to step S102.
[0038]
In step S102, a determination is made as to whether or not the ratio between an appropriate gear ratio determined in accordance with an estimated vehicle body speed VSO, which will be described later, and the actual gear ratio is greater than or equal to a predetermined value. If the ratio between the appropriate gear ratio and the actual gear ratio is smaller than a predetermined value, that is, if the deviation between the appropriate gear ratio and the actual gear ratio is within a predetermined range, the process proceeds to step S101. The normal ABS / EBD control that does not use the gear ratio information of the CVT 70 is executed. On the other hand, if the ratio between the appropriate gear ratio and the actual gear ratio is greater than or equal to the predetermined value, the process proceeds to step S104.
[0039]
In step S104, the ABS / EBD control start timing is set according to the gear ratio of the CVT 70. In the subsequent step S106, the hydraulic pressure amount for adjusting the brake hydraulic pressure in the wheel cylinders 51 to 54 is set according to the gear ratio of the CVT 70. The setting of the control start timing and the hydraulic pressure amount is specifically executed in the ABS / EBD control shown in FIG.
[0040]
Next, a method for setting the control start time and the hydraulic pressure amount will be specifically described with reference to FIGS. 4 is a flowchart of the ABS / EBD control, FIG. 5 is a diagram showing an example of a control start slip amount map of ABS control, FIG. 6 is a diagram showing an example of a pressure increase amount and pressure reduction amount map of ABS control, and FIG. These are figures which show an example of the control start slip amount map in EBD control.
[0041]
In step S200, it is determined whether or not the estimated vehicle speed VSO is equal to or higher than a predetermined vehicle speed VLCUT. If the estimated vehicle speed VSO is lower than the predetermined vehicle speed VLCUT, the process proceeds to step S216 without executing the ABS control. On the other hand, if the estimated vehicle speed VSO is equal to or higher than the predetermined vehicle speed VLCUT, the process proceeds to step S202.
[0042]
In step S202, a determination is made as to whether an ABS control start condition is satisfied. If the ABS control start condition is not satisfied, the process proceeds to step S216 without executing the ABS control. On the other hand, if the ABS control start condition is satisfied, the process proceeds to step S204.
[0043]
Here, the ROM of the ABS ECU 10 stores a map (ABS control start slip amount map) that defines the relationship between the gear ratio of the CVT 70 and the ABS control start wheel slip amount, and this map is based on the gear ratio of the CVT 70. The wheel slip amount at which the ABS control is started is obtained by searching the ABS control start slip amount map. Then, the control start wheel slip amount is compared with the actual slip amount to determine whether or not the control start condition is satisfied.
[0044]
As shown in FIG. 5, the control start slip amount map is set so that the wheel slip amount at which the ABS control is started decreases as the gear ratio of the CVT 70 increases in a predetermined gear ratio region (R1 to R2). Yes. Therefore, the greater the gear ratio of the CVT 70, that is, the greater the possibility that the wheel speed VW decreases due to engine braking, the earlier the timing at which the ABS control is started.
[0045]
Returning to FIG. 4 and continuing the description, in step S204, the pressure reduction, pulse pressure increase, or holding is performed in accordance with the braking condition determined based on the wheel speed VW, the wheel acceleration, and the estimated vehicle body speed VSO and the friction coefficient of the road surface. Either control mode is selected.
[0046]
In the subsequent step S206, it is determined whether or not the control mode selected in step S204 is the decompression mode. If the decompression mode is not selected, the process proceeds to step S208. If the decompression mode is selected, the process proceeds to step S210.
[0047]
If the decompression mode is selected, a decompression signal is output in step S210. Here, the ROM of the ABS ECU 10 stores a map (decompression amount map) that defines the relationship between the transmission ratio of the CVT 70 and the decompression amount. The decompression amount map is searched based on the transmission ratio of the CVT 70. Thus, the pressure reduction amount of the wheel cylinder hydraulic pressure is obtained. Then, a decompression signal is output according to the obtained decompression amount.
[0048]
The decompression amount map is set so that the decompression amount increases as the gear ratio of the CVT 70 increases in a predetermined gear ratio region (R3 to R4), as indicated by the solid line in FIG. Therefore, as the gear ratio increases, that is, as the possibility that the wheel speed VW decreases due to engine braking increases, the amount of reduction in the wheel cylinder hydraulic pressure increases.
[0049]
Returning to FIG. 4 and continuing the description, in step S208, it is determined whether or not the control mode selected in step S204 is the pulse increase mode. If the pulse increase mode is selected, the process proceeds to step S212. If the pulse increase mode is not selected, the process proceeds to step S214.
[0050]
When the step increase mode is selected, a pulse increase signal that alternately repeats pressure increase and holding is output in step S212. Here, the ROM of the ABS ECU 10 stores a map (pressure increase map) that defines the relationship between the gear ratio of the CVT 70 and the pressure increase amount. The map of the pressure increase amount is stored based on the gear ratio of the CVT 70. By searching, the pressure increase amount of the wheel cylinder hydraulic pressure is obtained. Then, a pulse increase signal is output according to the obtained pressure increase amount.
[0051]
The pressure increase amount map is set so that the pressure increase amount decreases as the gear ratio of the CVT 70 increases in a predetermined gear ratio region (R3 to R4), as indicated by a dotted line in FIG. Therefore, the greater the gear ratio, that is, the greater the possibility that the wheel speed VW will decrease due to engine braking, the smaller the wheel cylinder hydraulic pressure increase.
[0052]
Returning to FIG. 4 and continuing the description, in step S214, a holding signal is output and the wheel cylinder hydraulic pressure is held. The selection of the control mode and the output of the pressure increase / decrease signal are performed in the same way for each wheel FR, FL, RR, RL.
[0053]
Next, in step S216, a determination is made as to whether a control start condition for EBD control is satisfied. If the control start condition is not satisfied, the process ends without executing the EBD control. On the other hand, if the control start condition for EBD control is satisfied, the process ends after the EBD control is executed in step S218.
[0054]
Here, the ROM of the ABS ECU 10 stores a map (EBD control start slip amount map) that defines the relationship between the gear ratio of the CVT 70 and the EBD control start wheel slip amount, and this map is based on the gear ratio of the CVT 70. The wheel slip amount for starting the EBD control is obtained by searching the EBD control start slip amount map. Then, the control start wheel slip amount is compared with the actual slip amount to determine whether or not the control start condition is satisfied.
[0055]
As shown in FIG. 7, the control start slip amount map is set so that the wheel slip amount at which the EBD control is started decreases as the gear ratio of CVT 70 increases in a predetermined gear ratio region (R5 to R6). Yes. Therefore, the greater the gear ratio of the CVT 70, that is, the greater the possibility that the wheel speed VW will decrease due to engine braking, the earlier the timing at which the EBD control is started.
[0056]
Returning to FIG. 3 and continuing the description, in step S108, it is determined whether or not the vehicle body deceleration calculated from the change amount of the estimated vehicle body speed VSO is equal to or less than a predetermined value GL. Here, when the vehicle body deceleration is larger than the predetermined value GL, the process is terminated. On the other hand, when the vehicle body deceleration is equal to or less than the predetermined value GL, that is, when the amount of decrease in the estimated vehicle body speed VSO is small on a low μ road such as snow pressure or frozen, the process proceeds to step S110.
[0057]
In step S110, the control start slip amount of the ABS / EBD control is corrected according to the vehicle body deceleration. This correction process is specifically executed in step S202 in the ABS / EBD control shown in FIG.
[0058]
In this case, the ROM of the ABS ECU 10 stores in advance a control start slip amount correction gain map that defines the relationship between the vehicle body deceleration and the control start slip amount correction gain, and this control start slip amount based on the vehicle body deceleration. A correction gain map is searched to obtain a control start slip amount correction gain. Similarly, the ABS control start slip amount obtained in step S202 and the control start slip amount correction gain are integrated to calculate the corrected ABS control start slip amount. Then, whether or not the ABS control start condition in step S202 is satisfied is determined by comparing the corrected ABS control start slip amount with the actual slip amount.
[0059]
Further, the correction of the EBD control start slip amount is the same as the correction of the control start slip amount in the ABS control except that an EBD control start slip amount map is used instead of the ABS control start slip amount map. In this case, the determination as to whether or not the EBD control start condition in step S216 is satisfied is made by comparing the corrected EBD control start slip amount with the actual slip amount.
[0060]
Here, as shown in FIG. 8, in the control start slip amount correction gain map, the correction gain is fixed to a predetermined value K3 of 1.0 or less in a region of a predetermined vehicle body deceleration G3 or less. In the deceleration region (G3 to GL), the correction gain is set to increase from K3 to 1.0 as the vehicle body deceleration increases. Further, the correction gain is fixed to 1.0 in the region where the vehicle body deceleration GL or more. Therefore, the smaller the vehicle body deceleration, the smaller the control start slip amount at which ABS control and EBD control are started. Therefore, the control start timing of each of ABS control and EBD control is earlier than before the correction. It is done.
[0061]
In the subsequent step S112, the amount of increase or decrease in pressure for adjusting the brake fluid pressure in the wheel cylinders 51 to 54 is corrected in accordance with the vehicle body deceleration. This correction process is specifically executed in steps S210 and S212 in the ABS / EBD control shown in FIG.
[0062]
First, the correction of the decompression amount will be specifically described. The ROM of the ABS ECU 10 stores in advance a decompression amount correction gain map that defines the relationship between the vehicle body deceleration and the decompression amount correction gain, and the decompression amount correction gain map is retrieved based on the vehicle body deceleration to obtain the decompression amount. A correction gain is obtained. Then, the decompression amount obtained in step S210 and the decompression amount correction gain are integrated to calculate the corrected decompression amount. In this case, the pressure reduction signal in step S210 is output according to the corrected pressure reduction amount.
[0063]
Here, as shown in FIG. 9, the decompression amount correction gain map has a correction gain fixed at a predetermined value K4 of 1.0 or more in a region of a predetermined vehicle body deceleration G4 or less. In the region (G4 to GL), the correction gain is set to decrease from K4 to 1.0 as the vehicle body deceleration increases. Further, the correction gain is fixed to 1.0 in the region where the vehicle body deceleration GL or more. Therefore, the amount of pressure reduction in the ABS control is corrected so as to decrease as the vehicle body deceleration decreases.
[0064]
Next, the correction of the pressure increase amount will be specifically described. The ROM of the ABS ECU 10 stores in advance a pressure increase correction gain map that defines the relationship between the vehicle body deceleration and the pressure increase correction gain, and this pressure increase correction gain map is searched based on the vehicle body deceleration. Thus, a pressure increase correction gain is obtained. Then, the pressure increase amount obtained in step S212 and the pressure increase correction gain are integrated to calculate a corrected pressure increase amount. In this case, the pulse pressure increase signal in step S212 is output according to the corrected pressure increase amount.
[0065]
Here, as shown in FIG. 10, the pressure increase correction gain map has a correction gain fixed at a predetermined value K5 of 1.0 or less in a region of a predetermined vehicle body deceleration G5 or less. The correction gain is set to increase from K5 to 1.0 as the vehicle body deceleration increases in the speed region (G5 to GL). Further, the correction gain is fixed to 1.0 in the region where the vehicle body deceleration GL or more. Therefore, the amount of pressure increase in the ABS control is corrected so as to decrease as the vehicle body deceleration decreases.
[0066]
Next, in step S114, correction processing for the change gradient limit value when calculating the estimated vehicle body speed VSO is performed. Here, the estimated vehicle speed VSO is calculated according to the method shown in the flowchart of FIG. Next, a method for calculating the estimated vehicle body speed VSO will be described with reference to FIG. 11, and a correction process for the change gradient limit value of the estimated vehicle body speed VSO will be described.
[0067]
In step S300, a reduction rate restriction calculation is executed. Here, the content of the reduction rate restriction calculation will be described with reference to FIG.
[0068]
In step S400, DVSO is obtained by subtracting the previously calculated estimated vehicle speed VSO (n-1) from the previously calculated estimated vehicle speed VSO (n). Here, (n) or (n−1) is a subscript, indicating that the arithmetic processing cycle is the nth or n−1th time, and n is a natural number.
[0069]
In the subsequent step S402, DVSO and a constant K1 (a correction value corresponding to the subtraction of the estimated vehicle body speed VSO with respect to the actual vehicle body speed) are integrated to determine the deceleration rate αDN.
[0070]
In the next step S404, it is determined whether or not the deceleration rate αDN is less than a predetermined value K2 (a limit value for preventing the reduction rate from exceeding the tire limit). If the deceleration rate αDN is less than the predetermined value K2, the process returns to step S302 in FIG. On the other hand, if the deceleration rate αDN is greater than or equal to the predetermined value K2, the predetermined value K2 is assigned to the deceleration rate αDN in step S406, and then the process returns to step S302 in FIG.
[0071]
Returning to FIG. 11 and continuing the description, in step S302, a determination is made as to whether or not the ratio between the appropriate gear ratio determined in accordance with the estimated vehicle body speed VSO and the actual gear ratio is equal to or greater than a predetermined value. Here, when the ratio between the appropriate speed ratio and the actual speed ratio is smaller than a predetermined value, that is, when the deviation between the appropriate speed ratio and the actual speed ratio is within a predetermined range, the process proceeds to step S303. The normal estimated vehicle body speed calculation that does not use the gear ratio information of the CVT 70 is executed. On the other hand, if the ratio between the appropriate speed ratio and the actual speed ratio is greater than or equal to the predetermined value, the process proceeds to step S304.
[0072]
In step S303, the estimated vehicle speed VSO (n) is calculated based on the following equation (1).
[0073]
VSO (n) = MED (VW (n), VSO (n−1) −αDN · Δt, VSO (n−1) + αUP · Δt) (1)
Here, a value VSO (n−1) obtained by subtracting the deceleration amount αDN · Δt during Δt at the deceleration αDN from the current value VW (n) of the wheel speed and the previous value VSO (n−1) of the estimated vehicle body speed. −αDN · Δt and a value VSO (n−1) + αUP · Δt obtained by adding the increase amount αUP · Δt during Δt at a predetermined increase rate αUP to the previous value VSO (n−1) of the estimated vehicle body speed. The intermediate value of the three is calculated, and this is set as the current value VSO (n) of the estimated vehicle speed.
[0074]
In step S304, it is determined whether or not the vehicle body deceleration calculated from the change amount of the estimated vehicle body speed VSO is equal to or less than a predetermined value GL. Here, if the vehicle body deceleration is greater than the predetermined value GL, the process proceeds to step S303, and the above-described normal estimated vehicle body speed calculation is executed. On the other hand, when the vehicle body deceleration is equal to or less than the predetermined value GL, that is, when the amount of decrease in the estimated vehicle body speed VSO is small, for example, on a low μ road such as compressed snow or frozen, the process proceeds to step S306.
[0075]
In step S306, the estimated vehicle speed VSO (n) is calculated based on the following equation (2).
[0076]
VSO (n) = MED (VW (n), VSO (n−1) −αDN · G1 · Δt, VSO (n−1) + αUP · G2 · Δt) (2)
Here, the deceleration amount αDN during Δt at αDN · G1 obtained by correcting the deceleration αDN with the change gradient correction gain G1 from the current value VW (n) of the wheel speed and the previous value VSO (n−1) of the estimated vehicle body speed. The value VSO (n−1) −αDN · G1 · Δt obtained by subtracting G1 · Δt and the previous value VSO (n-1) of the estimated vehicle speed are corrected with the change gradient correction gain G2. A value VSO (n−1) + αUP · G2 · Δt, which is the sum of the acceleration increases αUP · G2 · Δt between Δt in αUP · G2, is calculated, and this is the estimated vehicle speed this time. The value VSO (n) is assumed.
[0077]
Here, the change gradient correction gain G1 for correcting the deceleration αDN is such that the gain decreases as the gear ratio of the CVT 70 increases in a predetermined gear ratio region (R7 to R8), as shown by a solid line in FIG. Is set to Therefore, on the low μ road surface, the deceleration amount αDN · G1 · Δt between Δt decreases as the gear ratio increases, that is, as the possibility that the wheel speed VW rapidly decreases due to engine braking increases.
[0078]
On the other hand, as shown by the dotted line in FIG. 12, the change gradient correction gain G2 for correcting the acceleration αUP is such that the gain increases as the gear ratio of the CVT 70 increases in the predetermined gear ratio region (R7 to R8). Is set. Therefore, on the low μ road surface, the greater the gear ratio, that is, the greater the possibility that the wheel speed VW will drop sharply due to engine braking, the greater the speed increase amount αUP · G2 · Δt during Δt.
[0079]
Thus, by setting the change gradient correction gains G1 and G2 in accordance with the CVT gear ratio, the change gradient limit value of the estimated vehicle body speed VSO can be corrected with the CVT gear ratio. Therefore, a rapid change in the estimated vehicle body speed VSO due to engine braking can be suppressed.
[0080]
After the estimated vehicle body speed calculation is completed, the process returns to the flowchart of FIG.
[0081]
Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, although the metal belt type CVT is used in the present embodiment, other methods such as a toroidal type CVT may be used. In the present embodiment, the map is used to obtain the control start slip amount, the pressure increase / decrease amount, and the like, but it is also possible to obtain it by an arithmetic expression.
[0082]
【The invention's effect】
As described above in detail, according to the present invention, when the actual gear ratio and the appropriate gear ratio deviate by a predetermined value or more, the control value for the brake fluid pressure control means to control the brake fluid pressure is set. Since the correction is made according to the actual gear ratio, even when the gear ratio of the continuously variable transmission deviates from an appropriate value, the anti-skid control can be appropriately performed. Therefore, it is possible to suppress a decrease in deceleration, vehicle stability, and steering performance during braking.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an overall configuration of an anti-skid control device according to an embodiment.
FIG. 2 is a skeleton diagram showing an example of a power transmission mechanism of a continuously variable transmission.
FIG. 3 is a diagram for explaining control value correction processing of ABS / EBD control in the anti-skid control device according to the embodiment;
FIG. 4 is a flowchart showing ABS / EBD control by the anti-skid control device according to the embodiment.
FIG. 5 is a diagram showing an example of a control start slip amount map in ABS control.
FIG. 6 is a diagram showing an example of a pressure increase amount / pressure reduction amount map in ABS control.
FIG. 7 is a diagram showing an example of a control start slip amount map in EBD control.
FIG. 8 is a diagram illustrating an example of a control start slip amount correction gain map;
FIG. 9 is a diagram illustrating an example of a decompression amount correction gain map;
FIG. 10 is a diagram illustrating an example of a pressure increase correction gain map.
FIG. 11 is a flowchart showing an estimated vehicle body speed calculation process.
FIG. 12 is a diagram showing an example of a change gradient correction gain map.
FIG. 13 is a flowchart showing a reduction rate restriction calculation process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Anti skid control apparatus, 10 ... ABS ECU, 10a ... Slip state detection part, 10b ... Brake fluid pressure control part, 10c ... Estimated vehicle body speed setting part, 10d ... Car body deceleration calculation part, 41-44 ... Wheel speed sensor 51-54 ... wheel cylinders, FR, FL, RR, RL ... wheels, 70 ... CVT, 80 ... CVT ECU.

Claims (5)

An anti-skid control device for a vehicle equipped with a continuously variable transmission whose speed ratio is controlled based on the speed of the vehicle,
Slip state detection means for detecting the slip state of the wheel;
Brake fluid pressure control means for controlling the brake fluid pressure of the wheel based on the slip state;
With
The anti-skid control device, wherein the brake fluid pressure control unit corrects a control value for controlling the brake fluid pressure when an actual transmission gear ratio and an appropriate transmission gear ratio deviate by a predetermined value or more. The control value is
2. The anti-skid control device according to claim 1, wherein the anti-skid control device is a brake fluid pressure control start timing and / or an increase / decrease amount. An estimated vehicle body speed is set based on a wheel speed, comprising: an estimated vehicle body speed setting means for limiting a change gradient of the estimated vehicle body speed when the estimated vehicle body speed is set;
The anti-skid control device according to claim 1 or 2, wherein the appropriate gear ratio is obtained according to the estimated vehicle body speed. A vehicle body deceleration calculating means for calculating a vehicle body deceleration based on a change amount of the estimated vehicle body speed;
4. The anti-skid control device according to claim 3, wherein the brake fluid pressure control unit corrects the control value according to the vehicle body deceleration when the vehicle body deceleration is a predetermined value or less. The estimated vehicle body speed setting means includes
The anti-skid control device according to claim 3 or 4, wherein when the vehicle body deceleration is larger than the predetermined value, the limit value of the change gradient is corrected according to the speed ratio.

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