JP4429076B2 - Braking force control device - Google Patents

Description

  The present invention relates to a braking force control device including a rear lift-up suppressing device.

In Patent Document 1, when a rear lift-up state is detected during anti-lock control, rear lift-up suppression is performed by suppressing the rear lift-up state by slowly reducing the hydraulic pressure of at least one brake cylinder of the left and right front wheels. A braking force control device including the device is described. Patent Document 2 describes a braking force control device including a rear lift-up suppressing device that performs low select control on the hydraulic pressure of the brake cylinders of the left and right front wheels.
JP-A-6-255468 JP 2003-95080 A

  An object of the present invention is to suppress a decrease in running stability caused by control of brake operating force by a rear lift-up suppressing device.

Means and effects for solving the problem

The braking force control device according to claim 1 is: (a) an antilock control device that separately controls at least the brake operating force of the left and right front wheels during braking of the vehicle, thereby separately controlling the slip state of the left and right front wheels. And (b) at least anti-lock control is performed on at least the left and right front wheels by the anti-lock control device, and the absolute value of the difference in the braking force between the left and right front wheels is not more than a set value. And a rear lift-up suppressing device having a rear lift- up suppressing unit that reduces the operating force difference when the rear lift- up state is detected and simultaneously reduces the brake operating force of the left and right front wheels. is, the brake force control apparatus according to claim 2, (a) and anti-lock control device, (c) at least, at least the left by the antilock control device A control unit for controlling the rear lift-up during the same control that simultaneously reduces the brake operating force of the left and right front wheels when the braking force of the front wheels is controlled in the same state and a rear lift-up state is detected; And a rear lift-up suppressing device.
In the anti-lock control device, at least the operating force of the brake of the left front wheel and the operating force of the brake of the right front wheel are controlled separately, respectively, and the slip state of the left front wheel and the slip state of the right front wheel However, each is controlled so as to be in an appropriate state determined by the friction coefficient of the road surface.
In the rear lift-up suppressing device, at least when the anti-lock control is performed on the left and right front wheels, and the rear lift-up state is detected, the braking force of the right front wheel and the braking force of the left front wheel Are simultaneously reduced. Therefore, it is possible to suppress the rear lift-up while suppressing a decrease in the running stability of the vehicle as compared with a case where the operating force of the left front wheel brake and the operating force of the right front wheel brake are separately reduced.
Further, in the braking force control device according to claim 3, the rear lift-up suppressing unit when the operating force difference is small has an absolute value of a difference in operating force between the brakes of the left and right front wheels being equal to or less than the set value. An operating force difference acquisition unit to acquire, and when the operating force difference acquisition unit acquires that the absolute value of the difference in operating force between the left and right front wheels is equal to or less than the set value, In the braking force control device according to claim 4, the rear lift-up suppressing unit during the control determines whether or not the operating force of the left and right front wheels is controlled in the same state. A means for determining, and when it is determined that the operating force is controlled in the same state with respect to the left and right front wheels, the operating force of the brakes on the left and right front wheels is simultaneously reduced.
Furthermore, in the braking force control device according to claim 5, the rear lift-up suppressing device performs anti-lock control on at least the left and right front wheels by the anti-lock control device, and the rear lift The non-decreasing portion that does not decrease the operating force of the brakes of the left and right front wheels when a predetermined operating force decrease prohibiting condition is satisfied even when an up state is detected, In the braking force control device, the rear lift-up suppressing device is configured such that the vehicle running speed when the anti-lock control is started is equal to or lower than a set speed, and the anti-lock control is performed when the wheel has a partial low μ road. Even if the rear lift-up state is detected in at least one of cases where the vehicle has started due to passing the vehicle, the brakes on the left and right front wheels It is intended to include non-decreasing portion during special anti-lock control which does not reduce the actuation force.
Further, in the braking force control device according to claim 7, the rear lift-up suppressing device includes a same-state operating force reducing unit that simultaneously reduces the operating force of the brakes of the left and right front wheels in the same state. In the braking force control device according to claim 8, the rear lift-up suppressing device simultaneously reduces the braking force of the left and right front wheels and reduces the braking force of at least one of the left and right rear wheels. The rear wheel operating force increasing portion to be increased is included.

Patentable invention

  In the following, the invention that is claimed to be claimable in the present application (hereinafter referred to as “claimable invention”. The claimable invention is at least the “present invention” to the invention described in the claims. Some aspects of the present invention, including subordinate concept inventions of the present invention, superordinate concepts of the present invention, or inventions of different concepts) will be illustrated and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combinations of the constituent elements constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

(1) an anti-lock control device for separately controlling the slip state of the left and right front wheels by separately controlling at least the braking force of the left and right front wheels during braking of the vehicle;
At least, when the anti-lock control is performed on at least the left and right front wheels by the anti-lock control device, and the rear lift up is detected, the rear lift that simultaneously reduces the brake operating force of the left and right front wheels. A braking force control device including an up suppression device.
(2) The braking force control device according to (1), wherein the rear lift-up suppressing device includes a rear lift-up detection device that detects that the vehicle is in a rear lift-up state.
(3) The rear lift-up detection device is configured such that (a) the vehicle deceleration is greater than or equal to the set deceleration, and (b) the rear wheel ground load is less than the set load, or the rear wheel ground load. The braking force control device according to item (2), wherein the rear lift-up state is established when at least one of the set load is smaller than the set load by the ground load of the front wheel.
Rear lift-up means that the ground contact load of the rear wheel decreases, and the resultant force of the vector of the load (vertical force) applied to the center of gravity of the vehicle and the vector of the inertial force (force in the front-rear direction) applied to the center of gravity. This occurs when the intersection of the vector extension line and the road surface is close to the ground contact point for the road surface of the front wheel. For example, when the center of gravity of the vehicle is forward or upward than when the load distribution is in a standard loading state, or when the inertial force is larger than the vertical force applied to the center of gravity (when the vehicle deceleration is large). It is easy to happen, especially when the load of the load loaded on the loading platform is small in a truck or the like, or when the load is not loaded (empty load).
From the above situation, if the vehicle deceleration is greater than or equal to the set deceleration, it is acquired that the vehicle is in the rear lift up state, or if the rear wheel ground load is less than the set load or the rear wheel ground load is It can be acquired that the rear lift is up when the contact load is smaller than the set load.
The vehicle deceleration can be detected directly by installing an acceleration sensor, or the estimated vehicle speed is obtained based on the maximum value of the wheel speeds of multiple wheels, and the estimated vehicle speed differential value (change over time) is used. It can be acquired indirectly such as. The set deceleration, which is the rear lift-up determination threshold value, can be set to a magnitude that can be estimated to cause rear lift-up.
Whether the rear wheel ground load is less than the set load or that the rear wheel ground load is smaller than the front wheel ground load by more than the set load can be detected directly by providing a load sensor or in wheel speed and anti-lock control. It can be estimated (obtained indirectly) based on the control state, vehicle height, and the like. For example, (i) the rear wheel rotational speed (circumferential speed) is lower than the set speed relative to the estimated vehicle body speed, or the rear wheel rotational speed is lower than the set speed relative to the front wheel rotational speed, (ii ) Both the brake operating force of the left rear wheel and the brake operating force of the right rear wheel are reduced in the antilock control, and (iii) the distance between the wheel side member and the vehicle body side member for the rear wheel When at least one of (the vehicle height) is equal to or higher than the set vehicle height or the vehicle height on the rear wheel side is greater than the vehicle height on the front wheel side is satisfied, the ground contact load of the rear wheel is satisfied. Can be small.
In the case of the rear lift-up state, the force applied from the road surface to the wheels is reduced, so that the rotational speed is reduced. Therefore, when the rotational speed of the rear wheel is smaller than the rotational speed of the front wheel or the estimated vehicle body speed, the rear lift-up state can be assumed. In the rear lift-up state, the rotational speed of the rear wheels is reduced, so that the estimated vehicle body speed is a magnitude corresponding to the rotational speed of the front wheels. Therefore, in the case of the above (i), it is substantially the same whether the rotational speed of the front wheels is a reference or the estimated vehicle body speed is a reference.
Further, as described above, when the ground contact load of the rear wheel is reduced, the slip is increased, and control for reducing the operating force in the antilock control is performed. Therefore, when the rear wheel is controlled to reduce the operating force by the antilock control device, the rear lift-up state can be assumed.
Further, when the load applied to the wheel is small, the vehicle height is relatively larger than when the load is large, and this can be used to detect that the ground contact load of the rear wheel is small.
It should be noted that the rear lift-up state is detected based only on whether (i) the vehicle deceleration is greater than or equal to the set deceleration, and (i) whether the vehicle deceleration is greater than or equal to the set deceleration. It is possible to accurately detect whether or not the detection is based on both (ii) whether or not the contact load of the rear wheel is small. As described above, the rear lift-up is less likely to occur when the center of gravity is located rearward or downward, even when the vehicle deceleration is the same, than when it is located forward or upward. Therefore, it is desirable to detect whether or not the vehicle is in the rear lift-up state in consideration of not only the magnitude of the vehicle deceleration but also the magnitude of the ground contact load on the rear wheels.
Further, since the rear lift-up normally occurs when the vehicle deceleration is large, the rear lift-up suppression control that simultaneously reduces the operating force of the brakes on the left and right front wheels can be referred to as a high G time specific control. The rear lift-up suppression control start condition can be referred to as a high G specific control start condition.

(4) When the rear lift-up suppression control start condition including the fact that the rear lift-up suppression device is performing anti-lock control on the left and right front wheels and the detection of the rear lift-up state is satisfied The braking force control device according to any one of (1) to (3), further including a rear lift-up suppression control unit that simultaneously reduces the braking force of the left and right front wheels.
In addition to the detection of the rear lift-up state during the anti-lock control, for example, (i) the rear lift-up suppression control that reduces the operating force of the left and right front wheels may cause a decrease in traveling stability. When at least one of the following conditions is satisfied: low, (ii) low impact on antilock control, (iii) normal system, (iv) not against the driver's intention to travel, etc. It can be assumed that the rear lift-up suppression control start condition is satisfied.
(i) For example, (a) the change in the absolute value of the yaw moment caused by simultaneously decreasing the brake operating force of the left and right front wheels The amount is below the set value (including the fact that the yaw moment generated by the rear lift-up suppression control is small), (b) the absolute value of the yaw moment acting on the vehicle at the present time Based on whether or not at least one of the following conditions is satisfied: (c) The possibility that the driving stability is low due to other causes (for example, the road surface condition is good) is satisfied. Can be determined.
(a) will be described later.
Regarding (b), it can be assumed that the absolute value of the yaw moment is not more than the set value when the turning state of the vehicle is not more than the set state. For example, when the turning radius is greater than or equal to the set value, the absolute value of the steering angle is less than or equal to the set steering angle, the absolute value of the yaw rate is less than or equal to the set yaw rate, or the case of not being in a spin state, etc. . When the yaw moment of the vehicle is small, a decrease in running stability can be suppressed even if the yaw moment changes due to the rear lift-up suppression control.
With regard to (c), in the case where the road surface is flat or not a bad road, it is possible that the possibility that the running stability is reduced due to the road surface state is low. For example, the case where the difference in unevenness on the road surface is equal to or less than the set value, the case where the rough road level is equal to or less than the set level, such as the case where the unevenness frequency is equal to or less than the set frequency, and the like are applicable.
For (ii), for example, that a set time or more has elapsed since the start of the antilock control, that the operating force is not being sharply decreased in the antilock control device, and that after the operating force is reduced It can be said that the anti-lock control has a small influence when at least one of the conditions such as not waiting for the recovery of the wheel speed and after the recovery of the wheel speed is satisfied. During anti-lock control, it is desirable to preferentially control the wheel slip to a magnitude corresponding to the friction coefficient μ of the road surface.
Furthermore, (iii) the rear lift-up suppression control is desirably performed when the rear lift-up suppression device, the antilock control device, and the like included in the system are normal.
In addition, it is desirable to be performed when (iv) the vehicle is not in the both-depressed state (when both the accelerator pedal and the brake pedal are depressed by the driver). This is because it is desirable for the vehicle to travel according to the driver's intention to travel in the both-stepped state, and it is not desirable to reduce the braking force applied to the vehicle by the control.
If the rear lift-up suppression control start condition including these conditions is satisfied, if the rear lift-up suppression control is performed, the influence on the antilock control can be reduced, which is contrary to the driver's driving intention. In addition, the rear lift up can be suppressed while suppressing a decrease in the running stability of the vehicle.
As will be described later, when the anti-lock control is being performed and the rear lift-up suppression control start condition is not satisfied even if the rear lift-up state is detected, the rear lift-up suppression control is not performed. You can also think that

(5) When the rear lift-up suppressing device detects that the rear lift-up state is detected when at least the brake operating force of the left and right front wheels is controlled in the same state by the antilock control device. The braking force control device according to any one of items (1) to (4), including a rear lift-up suppressing unit that controls the braking force of the left and right front wheels simultaneously.
The control in the same state corresponds to, for example, a state where both the braking force of the left front wheel brake and the braking force of the right front wheel are both increased, decreased, and held. The same state corresponds to a case where the direction of change of the operating force is the same, a case where the change gradient of the operating force is the same, a case where the amount of change is the same, a case where the control time is the same, and the like.
Note that the control in the same state in the braking force control device described in this section does not include control in which both the braking force of the right front wheel and the braking force of the left front wheel are both reduced with a steep slope. . This corresponds to the case where the control other than the control that is reduced by the steep slope is similarly performed on the left and right front wheels.
(6) In the case where the rear lift-up suppression device is controlled to increase both the brake operating forces of the left and right front wheels by at least the anti-lock control device, and the rear lift-up state is detected The braking force control device according to any one of (1) to (5), further including an increasing rear lift-up suppressing unit that simultaneously reduces the operating force of the brakes on the left and right front wheels.
(7) The anti-lock control device decreases the brake operating force of at least one of the left and right front wheels when a reduction condition including that a slip amount of at least one of the left and right front wheels is equal to or greater than a set amount is satisfied. An anti-lock actuation force decrease control unit; and an anti-lock actuation force increase control unit that increases when an increase condition including that at least one wheel acceleration of the left and right front wheels is greater than or equal to a set acceleration is satisfied, The rear lift-up restraining unit with the anti-lock actuating force increasing control unit increases both the actuating force of the right front wheel brake and the actuating force of the left front wheel brake, and the rear lift-up state is The braking force control device according to (6), which, when detected, simultaneously reduces the brake operating force of the left and right front wheels.
In the anti-lock control, the braking force of the wheel is controlled based on at least one of the wheel slip amount and the wheel acceleration, so that the slip amount of the wheel corresponds to the μ peak in FIG. This is a control that keeps it in the vicinity of the slip amount corresponding to the μ peak). In addition, not only a slip amount but a slip ratio can also be used.
In the anti-lock control, for example, the operating force is reduced when an anti-lock control start condition including that the slip amount of the wheel is equal to or greater than a set amount is satisfied. When the operating force exceeds the magnitude at which μ peak is realized (hereinafter referred to as μ peak corresponding operating force), that is, when the road friction coefficient μ becomes excessive, the amount of slip increases and the operating force It is reduced. The actuation force is reduced until it becomes less than the µ peak corresponding actuation force. As a result, the wheel speed increases, but when the wheel acceleration becomes equal to or higher than the set acceleration, the operating force is increased and brought close to the μ peak corresponding operating force.
On the other hand, when the brake operating force is smaller than the μ peak corresponding operating force, the braking force applied to the wheel also decreases as the brake operating force decreases. Decreasing increases the braking force. Therefore, when the brake operating force of one of the left and right front wheels is reduced by the anti-lock control device and the other is increased, if both brake operating forces of the left and right front wheels are reduced, There is a risk that a difference in braking force may occur between the two, the difference may increase, or the magnitude of the braking force may be reversed. When in the rear lift-up state, the grounding load on the rear wheels is small and the cornering force on the rear wheels is small, resulting in a braking force difference between the left and right front wheels, which increases the yaw moment. Is not desirable.
On the other hand, when the operating force is increased by the anti-lock operating force increase control unit, it is considered that the operating force is smaller than the μ peak corresponding operating force and is close to the μ peak corresponding operating force. Can do. By simultaneously reducing the braking force on the left and right front wheels, there is no difference in braking force, no difference is increased, and the magnitude of braking force is not reversed. It can be considered that the change is in a small state. Therefore, when both the left and right front wheel brake operating forces are increased by the anti-lock operating force increase control unit, when it is detected that the rear lift-up state is detected, the left and right front wheel brake operating forces are simultaneously decreased. Then, it is possible to suppress the rear lift up while suppressing the change in the yaw moment.
In the braking force control device described in this section, when the rear lift up is detected during the anti-lock control, the braking force of the left and right front wheels is not necessarily reduced, but the braking force of the left and right front wheels is not reduced. Decreased when both powers are increased. In other words, the reduction of the actuation force is permitted in a state where the change in the yaw moment resulting from the reduction of the brake actuation force of the left and right front wheels is small.
(8) The anti-lock actuation force increase control unit gradually increases the actuation force of the at least one brake when the slip amount of at least one of the left and right front wheels reaches the vicinity of the μ peak corresponding slip amount. An anti-lock actuation force slow increase control unit, wherein the restricted rear lift-up suppressing device is configured such that at least both brake operating forces of the left and right front wheels are increased by the anti-lock actuation force slow increase control unit; The braking force control apparatus according to (7), further including a slowly increasing rear lift-up suppressing unit that simultaneously reduces the brake operating force of the left and right front wheels when the rear lift-up state is detected.
According to the anti-lock actuation force slow increase control unit, the brake actuation force is increased with a gentle gradient so as not to exceed the μ peak corresponding actuation force. The operating force is not greatly changed, the amount of change in the brake operating force between the left and right front wheels is small, and the absolute value of the difference between the left and right operating forces is also small.

(9) It is estimated that the amount of change in the absolute value of the yaw moment of the vehicle when the rear lift-up suppressing device simultaneously reduces the brake operating force of the left and right front wheels is equal to or less than a set value; In any one of the items (1) to (8), including a yaw moment change small rear lift-up suppressing unit that simultaneously reduces the brake operating force of the left and right front wheels when the rear lift-up state is detected. The braking force control apparatus described.
(10) When the rear lift-up suppressing device has acquired that at least the absolute value of the difference in operating force between the brakes of the left and right front wheels is equal to or less than a set value, and detects the rear lift-up state The braking force control device according to any one of (1) to (9), further including a rear lift-up suppressing unit that reduces the operating force difference when the operating force of the left and right front wheels is reduced simultaneously.
That the absolute value of the difference between the brake operating force of the left front wheel and the brake operating force of the right front wheel is equal to or less than the set value is acquired by the operating force difference acquisition device.
The operating force difference acquisition device includes an operating force sensor that can detect the brake operating force of the right front wheel and the brake operating force of the left front wheel, or the brake operating force of the left and right front wheels based on the control mode by the antilock control device. It is also possible to include an operating force difference estimation device that estimates whether or not the difference is large.
It should be noted that at least when the difference in braking force applied to the left and right front wheels is acquired to be less than or equal to the set value and the rear lift-up condition is detected, the braking force of the left and right front wheels is reduced simultaneously. You can also
In addition, at least when the control range of the brake operating force of the left and right front wheels by the anti-lock control device is less than the set range and a rear lift up is detected, the brake operating force of the left and right front wheels is simultaneously reduced. It can also be made. When the change range of the brake operating force is equal to or less than the set range, it can be considered that the difference between the left and right brake operating forces is small.
(11) When the rear lift-up suppressing device is acquired that at least the brake operating force of the left and right front wheels is in the vicinity of the operating force corresponding to μ peak, and the rear lift-up state is detected, The braking force control device according to any one of (1) to (10), further including a rear lift-up suppressing unit at the time of reaching the μ peak that simultaneously reduces the braking force of the left and right front wheels.
As described above, during the control of the operating force by the anti-lock operating force slow increase control unit, it can be assumed that both the operating forces of the brakes on the left and right front wheels are in the vicinity of the μ peak corresponding operating force.
It should be noted that at least the brake operating force for the left and right front wheels should be reduced simultaneously when both the brake operating forces for the left and right front wheels are smaller than the μ peak operating force and a rear lift-up condition is detected. You can also
(12) When the anti-lock control device satisfies at least one brake operating force of the left and right front wheels and a sudden decrease condition including that the slip amount of at least one of the left and right front wheels is a set amount or more, The rear lift-up suppressing device includes a sudden / slowly decreasing portion that decreases with a steep slope in a predetermined pattern and then gradually decreases. Slowly decreasing rear lift-up suppression unit that reduces both the power and the braking force of the left front wheel with a gentle gradient and simultaneously reduces these operating forces when a rear lift-up condition is detected The braking force control apparatus according to any one of (1) to (11), including:
For example, when it is acquired that the wheel speed has been recovered by decreasing the operating force with a steep slope, the operating force can be decreased with a gentle slope.
In a state where the brake operating force is decreased with a steep slope (the decreasing slope of the operating force with respect to time is greater than or equal to the set slope), the magnitude of the braking force for the right front wheel and that for the left front wheel Is difficult to estimate. On the other hand, in a state where the gradient is decreased with a gentle gradient (the decreasing gradient is equal to or less than the above-described gradient), the absolute value of the difference between the braking force of the right front wheel and the braking force of the left front wheel Can be estimated to be small. Further, in a state where the pressure is decreased with a gentle gradient, the operating force is considered to be smaller than the μ peak corresponding operating force.
(13) The anti-lock control device reduces or holds at least one brake operating force of the left and right front wheels based on at least one of a slip amount and wheel acceleration of the left and right front wheels, The wheel slip state is controlled so as to approach an appropriate state determined based on the friction coefficient of the road surface, and the rear lift-up suppressing device is When both the braking force of the front wheel brake and the braking force of the left front wheel are maintained, and when a rear lift-up condition is detected, these lifting forces are reduced simultaneously. The braking force control device according to any one of (1) to (12), including a section.
For example, when the slip amount (which can also be referred to as a slip ratio; the same applies hereinafter) is equal to or greater than the first set amount and the wheel acceleration is equal to or less than the first set value, the operating force is decreased and the slip amount is equal to or greater than the first set amount. Thus, the control can be performed when the wheel acceleration is larger than the first set value and increased when the slip amount is equal to or less than the first set value.

(14) The rear lift-up suppressing device is predetermined even if anti-lock control is performed on at least the left and right front wheels by the anti-lock control device, and the rear lift-up state is detected. The braking force control device according to any one of (1) to (13), including a non-decreasing portion that does not decrease the operating force of the brakes on the left and right front wheels when the operating force decrease prohibiting condition is satisfied.
(15) The rear lift-up suppressing device includes: (i) a case where a traveling speed of the vehicle when the anti-lock control is started is equal to or lower than a set speed; In the case of special anti-lock control that does not reduce the brake operating force of the left and right front wheels even if the rear lift-up state is detected in at least one of the cases where the start is caused by passing through the μ road The braking force control apparatus according to any one of items (1) to (14), including a reduction unit.
(16) The rear lift-up suppressing device satisfies a predetermined operating force decrease prohibition condition even when both the left and right front wheel brake operating forces are increased and the rear lift-up state is detected. The braking force control device according to any one of (1) to (14), further including a special non-decreasing portion that does not decrease the braking force of the left and right front wheels.
Even when both the left and right front wheel brake operating forces are increased, at least one of the cases where there is a possibility that the braking force may be insufficient or the anti-lock control may be affected is satisfied. In some cases, it is not desirable to reduce the operating force of the left and right front wheel brakes.
Further, when the vehicle traveling speed when the antilock control start condition is satisfied is equal to or lower than the set speed, the low speed specific antilock control is performed. The set speed is, for example, a speed equal to or less than the minimum value at which the wheel rotation speed can be detected with high accuracy. In the low-speed specific antilock control, the reliability of the detected wheel speed is low, and therefore the operating force may be excessively decreased in the antilock control, and then the operating force is increased. However, it is considered that the braking force is insufficient. In the low-speed specific antilock control, the decrease gradient of the operating force is suppressed or the increase gradient is increased as compared with the normal antilock control. However, even in that case, if the operating force is increased during the low-speed specific antilock control and the operating force is decreased by the rear lift-up suppressing device, there is a possibility that the braking force is insufficient. Not desirable.
When passing through a manhole, a step or the like, the rotational speed of the wheel decreases, and when the antilock control start condition is satisfied, the partial low μ road corresponding antilock control is performed. For example, when antilock control is started for the rear wheels after the time determined based on the wheelbase and the vehicle speed has elapsed since the start of antilock control for the front wheels, the degree of drop in the wheel speed is abrupt. In such a case, it can be assumed that a partial low μ is passed. When passing through a partial low μ road, antilock control is essentially unnecessary. For this reason, in the anti-lock control corresponding to the partial low μ road, the decrease gradient of the operating force is suppressed or the increase gradient is increased. However, even in that case, if the anti-lock control corresponding to the partial low μ road is performed, the braking force may be insufficient. Therefore, it is desirable that the rear lift-up suppression control is not performed even if the rear lift-up state is detected while the brake operation force is being increased in the anti-lock control corresponding to the partial low μ road.
(17) The rear lift-up suppressing device is (i) waiting for a recovery of the wheel speed of at least one of the left and right front wheels in the anti-lock control; and (ii) after the anti-lock control is started. In at least one of the cases where the elapsed time is less than or equal to the set time, the anti-lock control dependent non-decreasing portion that does not decrease the operating force is included in any one of items (1) to (16) Braking force control device.
In normal anti-lock control, when waiting for the wheel speed to recover after the operating force has been reduced, the operating force is reduced to detect whether the reduction in operating force is insufficient. It is not desirable to do so. Depending on the anti-lock control, the wheel speed recovery waiting may be included in the pressure increasing mode after the operating force is reduced and the pressure increasing mode (slow pressure increasing mode) is set. In anti-lock control, if the operating force is decreased before the operating force is increased, it takes a long time to increase the operating force to an appropriate magnitude, which may result in insufficient braking force. Therefore, it is desirable that the rear lift-up suppression control is not performed when waiting for wheel speed recovery in anti-lock control or before a set time has elapsed since the start of anti-lock control.

(18) The rear lift-up suppressing device includes any one of the same-state operating force reduction units that simultaneously and simultaneously reduce the operating force of the left and right front wheel brakes. The braking force control device described in 1.
If the brake operating force for the left and right front wheels is simultaneously reduced in the same state, the difference in the brake operating force for the left and right front wheels after the control for reducing the operating force by the rear lift-up suppression device can be reduced, and the change in yaw moment can be reduced. can do.
“Decrease in the same state” means that the reduction amount of the operating force is the same, the reduction time is the same, the decrease gradient is the same, until the same operating force is reached (the operating force target value is It is the same). The state of the reduction control may be determined in advance or may be determined each time, for example, based on the degree of rear lift up (vehicle deceleration, the magnitude of the ground contact load on the rear wheel), or the like.
Note that normal antilock control is often performed after the actuation force reduction control by the rear lift-up suppressing device.

(19) The rear lift-up suppressing device includes a rear wheel operating force increase unit that simultaneously decreases the operating force of the left and right front wheel brakes and increases the operating force of at least one of the left and right rear wheels. Thru | or the braking force control apparatus as described in any one of (18) terms.
In the braking force control apparatus described in this section, the braking force of the left and right rear wheels is increased. When the rear lift up state is detected, if the rear lift up state is suppressed by reducing the braking force of the left and right front wheels and the ground contact load on the rear wheel increases, the rear wheel brake is applied accordingly. If the power is increased, the braking force can be increased. The braking force of the entire vehicle can be increased.
On the other hand, if the anti-lock control is performed after the rear lift-up suppression control, it is considered that the brake operating force of the rear wheel is increased, but if the rear wheel brake operating force is increased by the rear lift-up suppression device, When the ground contact load of the rear wheel increases, the braking force can be quickly increased without waiting for an increase in the operating force by the antilock control device.
Further, in the rear lift-up state, since the rotational speed of the rear wheels is reduced, control for reducing the operating force is performed by the antilock control device, and the operating force is usually reduced. Also in that sense, it is desirable to increase the brake operating force of the rear wheels in advance.
In any case, it is only necessary to increase the operating force of at least one of the left and right rear wheels. Even if the operating force of both the left and right rear wheels is increased, the operating force of either one of the brakes is increased. May be.
(20) The rear wheel operating force increasing section increases the operating force of at least one brake of the left and right rear wheels in accordance with an increase in the ground contact load of the rear wheels resulting from a decrease in the operating force of the brakes of the left and right front wheels. The braking force control apparatus according to item (19), including an increase state control unit.
The operating force of the rear wheels can be increased when the rear wheel ground load increases due to a decrease in the operating force of the left and right front wheels, or can be increased by an amount determined based on the amount of load increase.
The operating force of the left and right rear wheels may be increased simultaneously with the decrease of the operating force of the left and right front wheels, or may be increased after a set time has elapsed after the decrease of the operating force of the left and right rear wheels.
The amount of increase in the operating force can be determined according to the amount of decrease in the operating force of the left and right front wheels, or can be determined according to the amount of increase in the ground load on the rear wheels. For example, if the amount of increase in the operating force of the front wheels is increased by the same amount, a decrease in the braking force of the entire vehicle can be suppressed. Further, if the amount of increase of the set force or more than the amount of decrease in the operating force of the front wheels is increased, it is also possible to compensate for the decrease control due to the rear lift-up state by the antilock control device.

(21) At least one of a friction brake that is operated when the friction engagement member is pressed against the brake rotating body and a regenerative braking brake that is operated by regenerative braking of an electric motor that applies driving force to the wheels. The braking force control apparatus according to any one of (1) to (20), including:
When the brake is a friction brake, even if the brake is a hydraulic brake that suppresses the rotation of the wheel by pressing the friction engagement member against the brake rotating body by the hydraulic pressure of the brake cylinder, the pressing member is pressed by the operation of the electric motor. The electric brake which suppresses rotation of a wheel by pressing on a brake rotary body may be sufficient.
(22) The anti-lock control device includes: (i) an operating force control actuator capable of separately controlling the operating force of the left and right front wheel brakes; and (ii) a computer as a main component, based on the slip state of the wheels. The braking force control device according to any one of (1) to (21), including an actuator control unit that controls the power control actuator.
The actuation force control actuator can be a hydraulic control actuator that can independently control the hydraulic pressure of the brake cylinders of the left and right front wheels when it is a hydraulic brake, and the driving force of the electric motor when it is an electric brake. It is possible to include a drive circuit for controlling the above. In the case of a regenerative brake, an inverter that can control the current supplied to the electric motor can be included.
The operating force control actuator can be the same as the rear lift-up suppressing device. In other words, the rear lift-up suppression control is performed using the actuation force control actuator for anti-lock control.

(23) an antilock control device for separately controlling the slip state of the left and right front wheels by separately controlling at least the operating force of the brakes of the left and right front wheels during braking of the vehicle;
The anti-lock control device increases the brake operating force of the left and right front wheels, and when the rear lift-up state is detected, the rear lift up reduces the brake operating force of the left and right front wheels. A braking force control device including a suppression device.
The technical feature described in any one of the items (1) to (22) can be employed in the braking force control device described in this item.
(24) an anti-lock control device for separately controlling the slip state of the left and right front wheels by separately controlling at least the operating force of the brakes of the left and right front wheels during braking of the vehicle;
The anti-lock control device increases the brake operating force of the left and right front wheels, and the rear brake that suppresses the increase of the brake operating force of the left and right front wheels when a rear lift-up state is detected. A braking force control device including a lift-up suppressing device.
When the rear lift-up condition is detected and both the left front wheel brake operating force and the right front wheel brake operating force are increased by the antilock control device, the left front wheel brake operating force and the right front wheel Both the brake actuation force is reduced. By reducing the operating force of the left front wheel brake and the operating force of the right front wheel brake by the rear lift-up suppressing device, an increase in the operating force by the antilock control device is suppressed.
The technical feature described in any one of the items (1) to (23) can be employed in the braking force control device described in this item.
(25) an anti-lock control device for separately controlling the slip state of the left and right front wheels by separately controlling at least the braking force of the left and right front wheels during braking of the vehicle;
Rear lift up that reduces the braking force of the left and right front wheels when the braking force of the left and right front wheels is controlled in the same state by the anti-lock control device and a rear lift up state is detected. A braking force control device including a suppression device.
The technical feature described in any one of the items (1) to (24) can be employed in the braking force control device described in this item.
(26) an anti-lock control device for separately controlling the slip state of the left and right front wheels by separately controlling at least the braking force of the left and right front wheels during braking of the vehicle;
Rear lift up that simultaneously reduces the braking force applied to the left and right front wheels when the anti-lock control device controls at least one of the braking force of the left and right front wheels and detects a rear lift up state. A braking force control device including a suppression device.
In anti-lock control, the magnitude of the braking force does not always match the magnitude of the operating force. On the other hand, in the braking force control device described in this section, when the rear lift-up state is detected, the operation is not performed. The braking force is reduced at the same time by reducing the power. Since the rear lift-up suppression control is performed in a state where the braking force is decreased as the brake operating force decreases, the slip does not become excessive due to the rear lift-up suppression control.
The technical feature described in any one of the items (1) to (25) can be employed in the braking force control device described in this item.
(27) an anti-lock control device that separately controls the slip state of the left and right front wheels by separately controlling the operating force of at least the left and right front wheels when braking the vehicle;
The anti-lock control device increases the brake operating force of the left and right front wheels, and when nose dive is detected, the nose dive suppressing device simultaneously reduces the brake operating force of the left and right front wheels. A braking force control device characterized by comprising:
The technical feature described in any one of the items (1) to (26) can be employed in the braking force control device described in this item.

Hereinafter, a hydraulic brake device including a braking force control device according to an embodiment of the present invention will be described in detail with reference to the drawings.
Reference numeral 10 represents a brake pedal, reference numeral 12 represents a master cylinder, reference numerals 20 and 22 represent brake cylinders for the left and right front wheels FL and FR brakes 24 and 26, and reference numerals 30 and 32 represent brakes for the left and right rear wheels RL and RR. 34 and 36 brake cylinders are shown. In this embodiment, both the left and right front wheel brakes 24 and 26 and the left and right rear wheel brakes 34 and 36 are hydraulic brakes, but the left and right front wheel brakes 24 and 26 are disc brakes and the left and right rear wheel brakes 34. 36 are drum brakes.
The master cylinder 12 is of a tandem type and includes two pressure pistons. The front of each of the two pressure pistons is a pressure chamber. One of the two pressure pistons is linked to the brake pedal 10 via a vacuum booster 38. The left and right front wheel brake cylinders 20 and 22 are connected to one of the two pressurizing chambers, and the left and right rear wheel brake cylinders 30 and 32 are connected to the other. In this embodiment, there are two front and rear systems, the hydraulic pressures of the left and right front wheel brake cylinders 20 and 22 can be controlled separately, and the left and right rear wheel brake cylinders 30 and 32 are controlled in common. The

Holding valves 44 and 46 are respectively provided between the one pressurizing chamber and the left and right front wheel brake cylinders 20 and 22, and pressure reducing valves 50 and 52 are respectively provided between the brake cylinders 20 and 22 and the reservoir 48. Provided. The holding valves 44 and 46 are normally open electromagnetic open / close valves that are opened and closed by controlling the current supplied to the solenoid, and the pressure reducing valves 50 and 52 are normally closed electromagnetic open / closed that are opened and closed by controlling the current supplied to the solenoid. It is a valve. In addition, check valves 54 and 56 are provided in parallel with the holding valves 44 and 46, respectively. The check valves 54 and 56 allow the flow of hydraulic fluid from the brake cylinders 20 and 22 toward the master cylinder 12 and prevent the reverse flow.
A pump passage 58 extends from the reservoir 48 and is connected to the upstream side (master cylinder side) of the holding valves 44 and 46 between the pressurizing chamber of the master cylinder 12 and the brake cylinders 20 and 22 of the left and right front wheels. . A pump 60 and check valves 62 and 64 are provided in the pump passage 58. The hydraulic fluid in the reservoir 48 is pumped up by the pump 60 and returned to the master cylinder 12. The pump 60 is driven by an electric motor 66.
The hydraulic pressure in the left front wheel brake cylinder 20 is controlled by opening and closing the holding valve 44 and the pressure reducing valve 50, and the hydraulic pressure in the right front wheel brake cylinder 22 is controlled by opening and closing the holding valve 46 and the pressure reducing valve 52. The hydraulic pressures of the brake cylinders 20 and 22 are controlled independently.

A holding valve 70 and an LSP & BV (Load Sensing Proportioning Bypath Valve) 72 are provided between the other pressurizing chamber and the left and right rear wheel brake cylinders 30 and 32, and between the brake cylinders 30 and 32 and the reservoir 74. Is provided with a pressure reducing valve 76. The LSP valve 72 is a valve that can change the breakpoint hydraulic pressure of the proportioning valve in accordance with the ground contact load of the rear wheel. When the front wheel system fails, the hydraulic pressure of the master cylinder 12 is not reduced. It is transmitted to the brake cylinders 30 and 32 of the wheel. The holding valve 70 is a normally open electromagnetic open / close valve, and the pressure reducing valve 76 is a normally closed electromagnetic open / close valve. A check valve 78 is provided in parallel with the holding valve 70. The reservoir 74 and the upstream side of the holding valve 70 between the pressurizing chamber and the brake cylinders 30 and 32 are connected by a pump passage 80, and a pump 82 and check valves 84 and 86 are provided in the pump passage 80. The pump 82 is driven by an electric motor 88.
The hydraulic pressures of the brake cylinders 30 and 32 for the left and right rear wheels are commonly controlled by opening and closing the holding valve 70 and the pressure reducing valve 76.

Each of the electromagnetic on-off valves 44, 46, 50, 52, 70, 76 and the electric motors 66, 88 are controlled based on commands from the skid control computer 100. The skid control computer 100 includes an execution unit 102, a storage unit 104, an input / output unit 106, and the like. The input / output unit 106 includes wheel speed sensors 110 to 116 provided on the left and right and front and rear wheels, respectively, An acceleration sensor 118 for detecting the acceleration (deceleration) of the vehicle, a brake switch 120 for detecting that the brake pedal 10 is operated, an accelerator switch 122 for detecting that an accelerator pedal (not shown) is operated, a turning state acquisition device 124, and the like. Are connected to each other, and the above-described electromagnetic on-off valves and electric motors are connected via a drive circuit (not shown).
The turning state acquisition device 124 includes a yaw rate sensor, a lateral G sensor, and the like, and acquires whether or not the vehicle is in a spin state.
The storage unit 104 stores a rear lift-up suppression control program represented by the flowchart of FIG. 4, an antilock control program represented by the flowchart of FIG.

Usually, the electromagnetic on-off valve is in the illustrated original position. The holding valves 44, 46, and 70 are in an open state, and the pressure reducing valves 50, 52, and 76 are in a closed state.
When the brake pedal 10 is operated, a hydraulic pressure corresponding to the operating force is generated in the pressurizing chamber of the master cylinder 12 by a brake operation. The hydraulic pressure is supplied to the left and right front wheel brake cylinders 20 and 22, and the left and right rear wheel brake cylinders 30 and 32. The left and right front wheel hydraulic brakes 24 and 26 and the left and right rear wheel hydraulic brakes 34 and 36, respectively. Operated.

When the brake cylinder hydraulic pressure becomes excessive with respect to the friction coefficient μ of the road surface, the anti-lock control is performed when the slip state of the wheel approaches the locking tendency. An example of the antilock control will be described with reference to FIG. In this embodiment, the anti-lock control is performed based on the wheel slip amount, the wheel deceleration, and the like.
Although the hydraulic pressure of the brake cylinders 20, 22, 30, and 32 is increased by the brake operation by the driver, the pressure is maintained or reduced when a predetermined condition such as a tendency to lock is satisfied. The control for maintaining or reducing the hydraulic pressure of the brake cylinder is a control before the start of the antilock control, and is not included in the antilock control.
In this state, the antilock control is started when the antilock control start condition such as the slip amount of the wheel exceeding the set amount is satisfied. During anti-lock control, the hydraulic pressure of the brake cylinder is increased or decreased based on the slip amount of the wheel and the wheel acceleration (the wheel deceleration occurs when the value is negative).

The slip amount is a value obtained by subtracting the wheel speed from the estimated vehicle speed, and the estimated vehicle speed is the maximum value VWMAX of the rotational speeds (circumferential speeds) of the left and right front and rear wheels, and the previous estimated vehicle speed VSO (n−1). ), The intermediate value VSO (n) = MED {VWMAX, VSO (n−1) between the decreasing limit value VSO (n−1) −α and the increasing limit value VSO (n−1) + β. ) −α, VSO (n−1) + β}
As determined. The estimated vehicle speed this time is often determined to be the maximum value among the rotational speeds of the four wheels.
The decrease-side limit value and the increase-side control value are, for example, this time when it is assumed that the previous estimated vehicle body speed has changed with the vehicle acceleration lower limit value (vehicle deceleration upper limit value) gDW or the vehicle acceleration upper limit value gUP. The estimated vehicle speed can be set. α and β are expressed by the equation α = αDW · Δt
β = αUP · Δt
It can be expressed as Here, Δt is an estimated vehicle speed acquisition cycle time.

Hereinafter, a case where antilock control is performed on the left front wheel will be described.
When the antilock control start condition is satisfied for the left front wheel, the pressure reducing mode is set, the holding valve 44 is closed, and the pressure reducing valve 50 is opened. Thereby, the hydraulic pressure of the brake cylinder 20 is reduced. In a state where the antilock control start condition is satisfied, the hydraulic pressure of the brake cylinder is larger than the hydraulic pressure capable of realizing the μ peak in FIG. 8 (hereinafter referred to as “μ peak corresponding hydraulic pressure”), but the pressure reducing mode is set. As a result, it is made smaller than the liquid pressure corresponding to μ peak.
In this embodiment, in the decompression mode, the slow decompression control (sometimes referred to as the pulse reduction mode) is performed after the sudden decompression control is performed, but the slow decompression control is performed depending on the degree of recovery of the wheel speed of the left front wheel. Sometimes not done. The slow pressure reduction control is a control in which the pressure reducing valve 50 is alternately switched between an open state and a closed state, and the hydraulic pressure of the brake cylinder is changed to a duty ratio {eg, time in an open state / (time in an open state and closed state). The pressure is reduced at a gradient determined by

In the decompression mode, it is determined whether or not the wheel speed has recovered to the set state (for example, whether or not the wheel acceleration has exceeded the first set acceleration). If the wheel speed has recovered to the set state, the pulse increase mode is set. The In the pulse increase mode (which can be referred to as a slow pressure increase mode), the holding valve 44 is alternately switched between the open state and the closed state, and the hydraulic pressure in the brake cylinder is increased with a gradient determined by the duty ratio.
In this pulse increase mode, the holding valve 44 and the pressure reducing valve 50 are closed during the set time, whereby the hydraulic pressure of the brake cylinder 20 is held, and further recovery of the wheel speed is awaited. This period is referred to as a wheel return waiting phase.
When the wheel speed further recovers from the above set state (when the wheel acceleration exceeds the second set acceleration that is larger than the first set acceleration), the pressure increasing time control is performed, and then the pulse increasing variable control is performed. Is done. The period during which pressure increase time control and pulse increase variable control are performed is referred to as a μ peak search phase.

The pressure increase time control is a control for quickly increasing the brake cylinder hydraulic pressure to near the μ peak corresponding hydraulic pressure shown in FIG.
It can be seen that the road surface μ is lower when the pressure reduction time in which the pressure reduction mode immediately after the start of the antilock control is set is longer than when it is shorter. Further, based on the road surface μ, the fluid pressure corresponding to the μ peak can be found. Based on these, the amount of pressure increase required to bring the hydraulic pressure of the brake cylinder closer to the vicinity of the μ peak compatible hydraulic pressure can be found. In the pressure increasing time control, if the pressure is increased by the above-described pressure increasing amount determined based on the road surface μ or the like, the brake cylinder hydraulic pressure can be brought close to the μ peak corresponding hydraulic pressure. In the pressure increase time control, a predetermined number of pressure increase pulses are output (the holding valve 44 is duty controlled).
The pulse increase variable control is a control for gradually increasing the brake cylinder hydraulic pressure so as not to exceed the μ peak compatible hydraulic pressure, and the pressure is increased at a gradient determined based on the pressure reduction time, the slip amount at that time, and the like. .
Depending on the recovery state of the wheel speed, that is, when the wheel speed is sufficiently recovered in the wheel return waiting phase, the pulse increase variable control may be performed without performing the pressure increase time control.

The pressure increasing gradient in the pressure increasing time control (corresponding to the duty ratio of the holding valve 44 (the ratio of the opening time to the control time or the closing time)) is usually larger than the pressure increasing gradient in the pulse increasing variable control. The number of pulses output in the pressure increase time control (the number of times the holding valve 44 is switched to the open state) is determined in advance. If the pressure is reduced during the pressure increase time control, the pressure reduction control ends. Later, the remaining number of pulses is output. Thus, in the pressure increase time control, the brake cylinder hydraulic pressure is increased by a pressure increase amount determined based on the pressure reduction time or the like.
Further, when the antilock control end condition is satisfied, the end time control is performed. The antilock control end condition is satisfied when the traveling speed of the vehicle falls below a set speed that can be regarded as being in a stopped state, or when the slip amount falls below a set amount. In this case, the hydraulic pressure of the brake cylinder 20 is not immediately returned to the hydraulic pressure of the master cylinder 12 but is gradually increased.

On the other hand, when it is detected that the road has changed from the low μ road to the high μ road, control at the time of transfer is performed. In the transfer control, the hydraulic pressure of the brake cylinder is increased with a larger gradient than the pressure increase time control.
When an abnormality is detected in the system, backup pulse increase control is performed. Since it is not desirable to rapidly increase the hydraulic pressure in the brake cylinder, pulse increase is performed.

In addition, yaw control is performed during straddle road travel. The yaw control is a control for suppressing a decrease in running stability when antilock control is performed during straddle road running, and is a control for reducing the difference in braking force between the left and right front wheels (or the left and right rear wheels). In the yaw control, when the anti-lock start condition is satisfied for the wheel on the low μ side while traveling on a crossing road, the slow decompression mode and the pulse increasing mode are alternately set for the wheel on the high μ side. As a result, the brake cylinder hydraulic pressure is maintained at the set pressure. The set pressure is set to a value lower than the brake cylinder pressure (sometimes referred to as lock pressure) when the slip of the wheel on the high μ side becomes excessive. Further, normal antilock control is performed on the low μ side.
An example of the anti-lock control corresponding to a crossing is shown in FIG.
For example, when it is obtained that the vehicle is traveling on a straddle based on the increased slip state of the right front wheel (rotational speed drop state) and the left front wheel slip increase state, When anti-lock control is started for a wheel, the hydraulic pressure of the brake cylinder of the wheel on the high μ side is maintained and then slowly increased. This control to maintain the hydraulic pressure of the brake cylinder of the wheel on the high μ side and the control to increase the pressure slowly is called pre-control yaw control, of which holding control is called pre-control yaw control and before the control This is called Yawkon pulse increase.

Then, during the pre-control yaw control, a value obtained by subtracting (sum of pressure increase ΣTLU−sum of pressure reduction time ΣTLD) on the low μ side (sum of pressure increase time ΣTHU−sum of pressure reduction time ΣTHD) on the high μ side. The pressure increasing / depressurizing time difference ΔTHL, that is,
THL = (ΣTHU−ΣTHD) − (ΣTLU−ΣTLD)
When the yaw control start condition such as becomes larger than the first threshold is satisfied, the yaw control is started. As described above, the pulse increase mode and the pressure reduction mode are alternately set on the wheel on the high μ side.
In addition, when the yaw control end condition such that the pressure increase / depressurization time difference ΔTHL is smaller than the second threshold is satisfied, the yaw control is ended.
In this embodiment, pre-control yaw control (yaw control holding control, yaw pulse pulse increase control) and yaw control are collectively referred to as straddle-compatible antilock control. When a wheel on the low μ side is transferred to a high μ road, control at the time of transfer is performed for the wheel.

  Further, when the anti-lock control start condition is satisfied during low-speed traveling, specific anti-lock control at low speed is performed. Normally, the anti-lock control is performed when the traveling speed of the vehicle is equal to or higher than the first set speed determined based on the detection accuracy of the wheel speed sensors 110 to 116. In some cases, when the anti-lock start condition is satisfied, the specific anti-lock control at low speed is performed. In the low-speed specific antilock control, since the reliability of the wheel speed detected by the wheel speed sensors 110 to 116 is low, the pressure may be excessively reduced. For this reason, in the low-speed specific antilock control, the pressure reduction gradient in the pressure reduction mode is made smaller or the pressure increase gradient in the slow pressure increase mode is made larger than in the normal time antilock control.

In addition, when the rotation speed of the wheel decreases due to passing through a manhole, a step, or the like, and the antilock control start condition is satisfied thereby, partial anti-μ road antilock control is performed.
For example, when antilock control is started for the rear wheels after the time determined based on the wheelbase and the vehicle speed has elapsed since the start of antilock control for the front wheels, the degree of drop in the wheel speed is abrupt. In such a case, it can be assumed that a partial low μ is passed.
When passing through a partial low μ road, antilock control is essentially unnecessary. For this reason, in the anti-lock control corresponding to the partial low μ road, the decrease gradient of the operating force is suppressed or the increase gradient is increased.

In this embodiment, when both the left and right front wheels are in anti-lock control, the pulse increase mode is set for both the left front wheel and the right front wheel, and the rear lift up is detected. When the rear lift-up suppression control start condition including the high-G specific control start condition is satisfied, a pressure reduction mode having a predetermined pattern is simultaneously set for the left and right front wheels.
The conditions for starting the rear lift-up suppression control are (1) anti-lock control is permitted for each of the front, rear, left and right wheels, (2) the estimated vehicle speed is less than the second set speed greater than the first set speed, 3) The estimated vehicle speed at the start of anti-lock control is higher than the first set speed, (4) The road is good or the rough road level is lower than the set level, and (5) Both the left and right front wheels The pulse increase mode has been set, (6) No rear partial control, (7) No spin, (8) The acceleration sensor is normal, (9) No stepping, (10 It is assumed that the rear lift-up suppression control start condition is satisfied when all of (1) to (10) are satisfied, including the rear lift-up.

When the estimated vehicle body speed is equal to or lower than the second set speed, the brake cylinder hydraulic pressure may be reduced. When the estimated vehicle body speed is high, it is necessary to decelerate quickly. Therefore, it is not desirable to reduce the brake cylinder hydraulic pressure. However, if the estimated vehicle body speed is lower than the second set speed, the brake cylinder fluid is controlled in the rear lift-up suppression control. The pressure can be reduced. The second set speed is a threshold value as to whether or not the vehicle is sufficiently decelerated.
That the estimated vehicle body speed at the start of the antilock control is equal to or higher than the first set speed indicates that the antilock control is not the specific antilock control at the low speed.
Whether or not the road is a bad road is acquired based on the amplitude of the unevenness of the road surface, the frequency of the unevenness, and the like. It can be considered that the rough road level is lower than the set level when the amplitude of the unevenness is smaller than the set value, or when the frequency of the unevenness is lower than the set level. The uneven state of the road surface can be acquired based on the change amount of the wheel speed, the change speed, and the like.

During the pulse increase mode, since the change range of the hydraulic pressures of the left and right front wheel brake cylinders 20 and 22 is narrow, the absolute value of the hydraulic pressure difference between the left and right front wheel brake cylinders 20 and 22 is considered to be small. In this embodiment, the brake cylinder hydraulic pressure sensor for detecting the hydraulic pressure of the brake cylinder is not provided. However, when the pulse increase mode is set for both the left and right front wheels, the brake cylinders 20 and 22 for the left and right front wheels are set. It can be estimated that the difference in hydraulic pressure is small.
In addition, when the pulse increase mode is set, the brake cylinder hydraulic pressure is smaller than the μ peak corresponding hydraulic pressure. Therefore, if the hydraulic pressures of the left and right front brake cylinders 20, 22 are reduced, the braking force is surely reduced. be able to.
Furthermore, even if the hydraulic pressure of the brake cylinders 20 and 22 is reduced, a decrease in running stability can be suppressed.
Further, since the anti-lock control is after the decompression mode is finished, it is considered that the influence on the anti-lock control is small. If the pressure is reduced during the pressure reduction mode, then it takes a long time for the brake cylinder hydraulic pressure to reach a desired magnitude. Furthermore, in anti-lock control, it becomes difficult to accurately estimate the road surface μ and the like. On the other hand, while the pulse increase mode is set, even if the hydraulic pressure of the brake cylinders 20 and 22 is decreased, the influence on the antilock control is small.

As described above, there are various types of pulse increase modes. However, the yaw control, the pressure increase time control, the variable pulse increase, the transfer time control, and the backup valve increase in the anti-lock control corresponding to the crossing described above are the rear lift. Up suppression control is included in the permission conditions.
In anti-lock control during crossing travel, as shown in FIG. 3, if the yaw holding and yaw pulse increase are performed for the wheel on the high μ side, it is determined whether the yaw control start condition is satisfied. It is not desirable to reduce the hydraulic pressure of the brake cylinders 20 and 22 for the left and right front wheels.
On the other hand, during the yaw control, the hydraulic pressure of the brake cylinder on the high μ side and the hydraulic pressure of the brake cylinder on the low μ side are considered to be smaller than the hydraulic pressure corresponding to the μ peak respectively. Even if both the hydraulic pressures are reduced, it is considered that the possibility that the running stability is lowered is low. Therefore, when the pulse increase mode is set for the wheel on the high μ side during the yaw control, and the pulse increase mode is set for the anti-lock control for the wheel on the low μ side, the rear lift-up suppression control is permitted. is there.
Even if the left and right wheels shift to the same μ road surface, the above-described pressure increase / decrease time difference ΔTHL does not immediately fall below the threshold value, and the yaw control end condition is not easily satisfied. Therefore, it is not desirable that the rear lift-up suppression control is prohibited during the yaw control.

On the other hand, even in the pulse increase mode, when in the wheel return waiting phase, when increasing the pulse during specific antilock control at low speed, when increasing the pulse during partial low μ road antilock control, When the yaw pulse is increased in the anti-lock control corresponding to the fork road, it is not included in the permission condition for the rear lift-up suppression control.
This is because it is not desirable to further reduce the pressure (not based on the slip state) in the wheel return waiting phase, that is, in the period for checking whether or not the pressure reduction is insufficient. In addition, when the pulse is increased during specific antilock control at low speed, or when the pulse is increased during antilock control corresponding to a partial low μ road, there is a possibility that insufficient braking force may be generated. .

The above-mentioned rear partial control means that the anti-lock control is performed only for the left and right rear wheels because the holding valve and the pressure reducing valve of the front wheel system are abnormal. During the rear partial control, the brake operation for the left and right front wheels is performed. It is undesirable for the power to be reduced.
In addition, when the vehicle is spinning, if the hydraulic pressure of the brake cylinders 20 and 22 for the left and right front wheels is reduced, the running stability may be reduced. Therefore, the absence of spin is a permission condition for the rear lift-up suppression control. For example, when the strength of the spin tendency obtained based on the yaw rate, the lateral G, or the like is equal to or higher than a set level, it can be assumed that spin is generated.
Furthermore, it is desirable that the rear lift-up suppression control is not performed even when the acceleration sensor 118 is abnormal. This is because the detection value of the deceleration used for determining whether or not the rear lift is up is not reliable.
When both the brake pedal 10 and an accelerator pedal (not shown) are depressed, it is desirable that the braking / driving state of the vehicle is determined according to the driver's operation. It is not desirable to reduce the cylinder hydraulic pressure. Therefore, the condition for permitting the rear lift-up suppression control is not to be in the both-stepping state.

Further, the rear lift-up detection conditions are: (a) the decompression mode is set for the rear wheels, (b) (i) the rear wheel rotational speed VwR is smaller than the estimated vehicle speed Vso by a set value ΔVsw, In addition, the vehicle deceleration G is greater than or equal to the set deceleration Gs, or (ii) the rear wheel rotational speed VwR is smaller than the front wheel rotational speed VwF by the set value ΔVRS and the vehicle deceleration G is the set value. It is assumed that the rear lift-up state occurs when both (a) and (b) are satisfied.
VwR ≦ Vso−ΔVsw, G> Gs
Or VwR ≦ VwF−ΔVRS, G> Gs
The set deceleration Gs, which is a threshold value of the vehicle deceleration G, can be set to a predetermined set value or can be determined each time.

  Rear lift-up is when the center of gravity of the vehicle is ahead or upward than when the load distribution is in a standard loading state, and when the inertial force is greater than the vertical force applied to the center of gravity (when the vehicle deceleration is large). In particular, in a truck or the like, it is likely to occur when the load of the load loaded on the loading platform is small or when the load is not loaded (empty load). In other words, even if the vehicle deceleration is the same, it is less likely to occur when the center of gravity is located rearward or downward than when it is located forward or upward. Therefore, if the rear lift-up state is detected in consideration of not only the magnitude of the vehicle deceleration but also the rotational speed of the rear wheels, it can be detected more accurately.

When the rear lift-up suppression control start condition is satisfied, the rear lift-up suppression control is executed. As shown in FIG. 5, the pressure reducing valves 50 and 52 of the front wheel system are simultaneously opened during a predetermined pressure reducing time TfD, and then closed during a predetermined holding time TfH. As shown in FIG. 6, the holding valve 70 of the rear wheel system is opened for a predetermined pressure increasing time TrU, and then closed for a predetermined holding time TrH.
The pressure reduction time TfD on the front wheel side and the pressure increase time TfU on the rear wheel side may be the same or different. If the time is the same, a decrease in the braking force on the front wheel side can be compensated for on the rear wheel side. Further, the holding time TfH of the pressure reducing valves 50 and 52 and the holding time TrH of the holding valve 70 may be the same or different, and the front wheel side control time Tf obtained by combining the pressure reducing time TfD and the holding time TfH; The rear wheel side control time Tr, which is the sum of the pressure increasing time TrU and the holding time TrH, may be the same or different.
After the end of the rear lift-up suppression control, normal antilock control is performed.
For the left and right front wheels, the pulse increase mode is continuously performed after the rear lift-up suppression control is completed. When the pressure increasing time control is performed when the rear lift-up suppression control start condition is satisfied, the pulse increasing variable control is performed after the remaining number of pulses are output. For the left and right rear wheels, the variable pulse increase mode is set and normal antilock control is performed.

It is determined whether the rear lift-up suppression control end condition is satisfied during the rear lift-up suppression control. When the rear lift-up suppression control end condition is satisfied, the rear lift-up suppression control is interrupted. This is also satisfied when the rear lift-up suppression control ends.
Rear lift-up suppression control termination conditions are (1) Anti-lock control is prohibited for each of the front, rear, left and right wheels, (2) Rear lift-up suppression control is terminated, (3) Bad road level is high, (4) A mode other than the pulse increase mode is set, (5) Rear partial state, (6) Spin is generated, (7) Acceleration sensor 118 is abnormal, (8) It is satisfied when at least one of these (1) to (9) is satisfied, including that the vehicle is stepped on both sides and (9) the vehicle deceleration is equal to or less than the set deceleration.
Conditions (1) to (9) are when there is a possibility that the running stability may be reduced by the rear lift-up suppression control, when the system is abnormal, when the rear lift-up state is cleared, or when both steps are It is desirable that the rear lift-up suppression control is not performed when these conditions are satisfied.

The antilock control program represented by the flowchart of FIG. 7 is executed at predetermined time intervals.
In step 1 (hereinafter simply referred to as S1. The same applies to other steps), it is determined whether or not the antilock control is being performed. If the antilock control is not being performed, it is determined in S2 whether or not the antilock control start condition is satisfied. If the antilock control start condition is satisfied, it is determined in S3 whether or not the speed is low (whether or not it is equal to or lower than the first set speed). In S4, whether or not the road is a partial low μ road. In S5, it is determined whether or not the road is a straddle. Otherwise, normal antilock is performed, so that the normal antilock flag is set in S6, and normal antilock control is executed in S7.

When the traveling speed of the vehicle is equal to or lower than the first set speed, the low-speed specific antilock control in-progress flag is set in S8, and the low-speed specific antilock control is executed in S9.
When it is detected that the partial low μ road has been passed, the partial low μ road corresponding anti-lock control flag is set in S10 and 11, and the partial low μ road corresponding anti-lock control is executed.
If it is detected that the vehicle is traveling on a crossing road, the crossing road corresponding antilock control flag is set in S12, and the crossing road antilock control is executed in S13. For the wheel on the high μ side, any one of the pre-control yaw control holding mode, the pre-control yaw control pulse increase mode, the slow decompression mode during yacon control, and the pulse increase mode during yaw control is set.

  On the other hand, if the antilock control is being performed, it is determined in S14 whether or not the antilock control end condition is satisfied. If the antilock control end condition is not satisfied, the antilock control corresponding to the type of flag is continuously performed (S7, 9, 11, 13). If the antilock control end condition is satisfied, an end process is performed in S15. Control at the end is performed, and the anti-lock control flag is reset.

The rear lift-up suppression control program represented by the flowchart of FIG. 4 is executed every set time.
In S21, it is determined whether or not the rear lift-up suppression control is being performed. If the rear lift-up suppression control is not being performed, it is determined in S22 whether the vehicle is in the rear lift-up state, in S23, whether the pulse increase mode is set for the left and right front wheels, and in S24, the vehicle is not in the spin state. It is determined whether other conditions such as are satisfied. If the determination in S22-24 is YES, it is determined that the rear lift-up suppression control start condition is satisfied, and in S25, the control command having the pattern shown in FIG. 5 is output to the front wheel pressure reducing valves 50, 52. In S26, a control command having a pattern shown in FIG. 6 is output to the rear wheel holding valve 70. Further, when a control command is output, a rear lift-up suppression control in-progress flag is set.

On the other hand, when the rear lift-up state is not set and the pulse increase mode is not set for the left and right front wheels, the rear lift-up suppression control is not performed. Even if the rear lift-up is detected, if the pulse increase mode is not set for the left and right front wheels, the rear lift-up suppression control is not performed.
If the rear lift-up suppression control flag is set, it is determined in S27 whether the rear lift-up suppression control end condition is satisfied. If the rear lift-up suppression control end condition is satisfied, in S28, a rear lift-up suppression control end processing command is output, and the rear lift-up suppression control in-progress flag is reset. When the rear lift-up suppression control end condition is satisfied by the completion of the rear lift-up suppression control, the pulse increase mode is set for the front wheels and the rear wheels. Thereafter, the hydraulic pressures of the brake cylinders for the front wheels and the rear wheels are controlled according to the execution of the normal antilock control program.
Further, when the rear lift-up suppression control end condition is satisfied for other reasons, the rear lift-up suppression control is interrupted, and normal antilock control is immediately performed.

As described above, in the present embodiment, when the rear lift-up suppression control start condition is satisfied, the pressure reducing command (command for opening the pressure reducing valves 50 and 52) for the left and right front wheel brake cylinders 20 and 22 is simultaneously output. The Therefore, the hydraulic pressures of the brake cylinders 20 and 22 for the left and right front wheels are simultaneously reduced, the difference in braking force between the left and right front wheels can be reduced, and a decrease in running stability can be suppressed.
Further, the opening time (pressure reduction time) of the pressure reducing valves 50 and 52 for the left and right front wheels is set to the same length. Therefore, the hydraulic pressure difference between the brake cylinders 20 and 22 for the left and right front wheels can be reduced, and a decrease in running stability can be further suppressed. In addition, as in this embodiment, when the brakes are hydraulic brakes 24 and 26 and the hydraulic pressures of the brake cylinders 20 and 22 are smaller than the μ peak corresponding hydraulic pressure, the pressure reducing valves 50 and 52 are open for the same time. If so, the pressure reduction amount of the higher hydraulic pressure becomes larger than the pressure reduction amount of the lower hydraulic pressure, so that the hydraulic pressure difference between the brake cylinders 20 and 22 of the left and right front wheels becomes small.
Further, the hydraulic pressure in the brake cylinders 30 and 32 for the rear wheels is increased. Therefore, when the ground load on the rear wheel increases due to the rear lift-up suppression, the rear wheel braking force can be quickly increased. The hydraulic pressures of the brake cylinders 30 and 32 of the rear wheels are gradually increased by setting the pulse increasing mode in the normal antilock control after the rear lift-up suppression control is finished. If the pressure is increased in advance in the rear lift-up suppression control, the rear wheel braking force can be quickly increased, and a decrease in the braking force of the entire vehicle can be suppressed.

Furthermore, when a rear lift up is detected during the anti-lock control, the rear lift up suppression control is not performed, but the rear lift up suppression including that the pulse increase mode is set for both the left and right front wheels. This is performed when the control start condition is satisfied. Therefore, a change in yaw moment resulting from the rear lift-up suppression control can be suppressed, and a decrease in running stability can be suppressed.
In addition, when the decrease in running stability caused by the rear lift-up suppression control is suppressed, the vehicle deceleration determination threshold value for whether or not the rear lift is up can be increased. Rear lift-up suppression control can be performed while suppressing an increase in braking distance.

In the present embodiment, the holding valve 44, 46, 70, the pressure reducing valve 50, 52, 76, the part for storing the anti-lock control program represented by the flowchart of FIG. A lock control device is configured.
Further, the pressure reducing valves 50 and 52, the holding valve 70, the part for storing the rear lift-up suppression control program represented by the flowchart of FIG. . The rear lift-up suppressing device is also an increasing rear lift-up suppressing unit, a controlling rear lift-up suppressing unit, an operating force difference small rear lift-up suppressing unit, and a same-state operating force decreasing unit. In addition, a rear wheel operating force increasing portion is configured by a portion that stores the holding valves 70 and S24 of the rear lift-up suppressing device, a portion that executes the holding valve 70, and the like. The rear lift-up suppressing device and the antilock control device share the holding valve 70, the pressure reducing valves 50, 52, and the like. A hydraulic pressure control actuator is constituted by the holding valve 70, the pressure reducing valves 50, 52 and the like.
Furthermore, when any one of S22, 23, and 24 is determined as NO in the rear lift-up suppressing device, a non-decreasing portion is configured by a portion that does not execute S24 and 25.
Further, the acceleration sensor 118, the wheel speed sensors 110 to 116, the part that stores S22 of the skid control computer 100, the part that executes it, and the like constitute a rear lift-up acquisition device.

The rear lift-up suppression control start condition is not limited to that in the above embodiment. The rear lift-up suppression control may be performed when the rear lift-up state is satisfied and both the left and right front wheels are set to the pulse increase mode.
Further, the rear lift-up suppression control can be performed during the slow pressure reduction control instead of the pulse increase mode. This is because it is considered that the hydraulic pressure difference between the left and right front brake cylinders 20 and 22 is small even during the slow pressure reduction control.
Furthermore, the condition of the rear lift-up state is not limited to that in the above embodiment. For example, an up / down stroke sensor that detects a stroke between a wheel side member and a vehicle body side member with respect to a rear wheel and a front wheel is provided, and when the up / down stroke of the rear wheel is equal to or greater than a set value, the up / down stroke of the rear wheel It can be determined that the rear lift-up state is established when it is larger than a set value with respect to the vertical stroke of the rear. In addition, a load sensor for detecting the ground contact load of the rear wheel may be provided on the rear axle or the like, and the rear lift-up state may be established when the ground load of the rear wheel becomes a set value or less.
In addition, when the yaw control is performed in the crossover antilock control, the rear lift-up suppression control can be prevented from being performed. This is because there is a certain difference in braking force between the left and right front wheels even when yaw control is performed during driving on a lane.

  Further, in the rear lift-up suppression control, the decompression time of the decompression valves 50 and 52 is determined according to the magnitude of the vehicle deceleration when the rear lift-up is detected, or according to the ground load of the rear wheels. You can also do it. It is also possible to reduce the pressure until the ground contact load of the rear wheel becomes equal to or higher than a set value.

Furthermore, it is not essential to provide the acceleration sensor 118, and the vehicle deceleration can be obtained by differentiating the estimated vehicle body speed.
In a brake device provided with a brake cylinder hydraulic pressure sensor for detecting the hydraulic pressure of the brake cylinder, it is directly determined that the absolute value of the hydraulic pressure difference between the left and right front wheel brake cylinders 20 and 22 is equal to or less than a set value. Can be detected. One of the conditions for starting the rear lift-up suppression control is that the absolute value of the difference between the detected hydraulic pressures of the left and right front wheel brake cylinders 20 and 22 is not more than a set value.

Furthermore, the mode of antilock control is not limited to that in the above embodiment. (a) Either a pressure reduction mode (including a slow pressure increase mode) or a pressure increase mode (including a slow pressure increase mode) can be set, or (b) a pressure reduction mode (including a slow pressure decrease mode) can be maintained. It is possible to use a control in which any one of a mode and a pressure increasing mode (including a slow pressure increasing mode) is set. For example, in the anti-lock control in which any one of pressure increase, hold, and pressure reduction is set based on the slip state of the wheel, the rear lift-up suppression control start condition 1 is that the pressure increase mode or the hold mode is set. It can be one. Further, it is not essential to perform the low select control in common for the rear wheels, and the antilock control can be separately performed for the left and right rear wheels.
Further, in the rear lift-up suppression control, it is not essential to increase the hydraulic pressure of the brake cylinders 30 and 32 for the rear wheels. If the hydraulic pressures in the brake cylinders 20 and 22 for the left and right front wheels are simultaneously reduced, the rear lift up can be suppressed.
The brake circuit to which the present invention is applied is not limited.
Furthermore, the brake is not limited to a hydraulic brake, and can be applied to an electric brake or a regenerative brake. Furthermore, the present invention can be applied to a vehicle provided with both a hydraulic brake and an electric brake friction brake and a regenerative brake. The brake operating force can be controlled by controlling the regenerative brake or the friction brake.
In addition to the above-described embodiments, the present invention can be carried out in various modifications and improvements based on the knowledge of those skilled in the art.

It is a circuit diagram of the whole brake device provided with the hydraulic control device which controls the hydraulic pressure of a brake cylinder as a braking force control device which is one example of the present invention. It is a figure which shows an example of the change state of the hydraulic pressure of a brake cylinder, and a wheel speed when antilock control is performed in the said brake device. In the said brake device, it is a figure which shows an example of the change state of the hydraulic pressure of a brake cylinder when antilock control is performed during straddle road driving | running | working. It is a flowchart showing the rear lift-up suppression control program memorize | stored in the memory | storage part of the said hydraulic-pressure control apparatus. It is a figure which shows notionally the control command signal output according to execution of the said rear lift up suppression control program. It is a figure which shows notionally the control command signal output according to execution of the said rear lift up suppression control program. It is a flowchart showing the anti-lock control program memorize | stored in the memory | storage part of the said hydraulic-pressure control apparatus. It is a figure showing the relationship between the slip amount and braking force in the vehicle during braking.

Explanation of symbols

44, 46, 70: Holding valve 50, 52, 76: Pressure reducing valve 100: Skid control computer 110-116: Wheel speed sensor 118: Acceleration sensor

Claims (8)

An anti-lock control device for separately controlling the slip state of the left and right front wheels by separately controlling the braking force of at least the left and right front wheels during braking of the vehicle;
At least anti-lock control is performed on at least the left and right front wheels by the anti-lock control device , and it is acquired that the absolute value of the difference in operating force between the brakes on the left and right front wheels is equal to or less than a set value, and A braking force including a rear lift-up restraining device having a rear lift- up restraining portion for reducing the actuation force when the rear lift-up state is detected, and simultaneously reducing the actuation force of the brakes of the left and right front wheels. Control device. An anti-lock control device for separately controlling the slip state of the left and right front wheels by separately controlling the braking force of at least the left and right front wheels during braking of the vehicle;
At least, when the braking force of the left and right front wheels is controlled at the same state by the anti-lock control device and the rear lift-up state is detected, the braking force of the left and right front wheels is simultaneously reduced. And a rear lift-up restraining device having a rear lift- up restraining part during the control. When the operating force difference is small, the rear lift-up suppressing unit includes an operating force difference acquisition unit that acquires that the absolute value of the difference in operating force between the brakes of the left and right front wheels is equal to or less than the set value. 2. The control according to claim 1, wherein when the absolute value of the difference in operating force between the left and right front wheels is acquired by the unit is equal to or less than the set value, the operating force of the brakes on the left and right front wheels is simultaneously reduced. Power control device. The rear lift-up suppressing unit during the control includes a means for determining whether or not the operating force of the left and right front wheels is controlled in the same state, by which the operating force is applied to the left and right front wheels in the same state. The braking force control apparatus according to claim 2, wherein when it is determined that the brake is controlled, the braking force of the left and right front wheels is simultaneously reduced. Even if the rear lift-up suppressing device is anti-lock controlled to at least the left and right front wheels by the anti-lock control device and the rear lift-up state is detected, a predetermined reduction in operating force is achieved. The braking force control device according to any one of claims 1 to 4, further comprising a non-decreasing portion that does not decrease the braking force of the left and right front wheels when a prohibition condition is satisfied. The rear lift-up suppression device is caused when the vehicle traveling speed when the anti-lock control is started is equal to or lower than a set speed, and when the anti-lock control has passed through a partial low μ road. in at least one of the case initiated Te, the even rear lift-up state is detected, claims 1 comprises the left and right front wheels during special anti-lock control which does not reduce the operation force of the brake non-decreasing portion 5 The braking force control apparatus as described in any one of these. The braking force control according to any one of claims 1 to 6, wherein the rear lift-up suppressing device includes a same-state operating force reduction unit that simultaneously and simultaneously reduces the operating force of the brakes of the left and right front wheels. apparatus. Any the rear lift-up suppression device, along with reducing the operation force of the left and right front wheel brake simultaneously claims 1 comprises a crop rotation power increasing portion after increasing the actuation force of at least one brake of the left and right rear wheels 7 of the The braking force control apparatus as described in any one.

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