Automatic brake device for saddle riding type vehicle

1. An automatic brake device for a vehicle, the automatic brake device comprising:

a front brake and a rear brake configured to be actuated independently of each other; and

a brake modulator configured to control actuation of the front and rear brakes,

the brake modulator including

collision possibility determining means for determining a possibility of collision of the vehicle with a front obstacle,

automatic brake control means for performing automatic brake control that automatically increases braking forces of the front and rear brakes when the collision possibility determining means determines that there is a possibility of collision, and

brake operation determining means for determining presence or absence of brake operation by a driver of the vehicle,

wherein the automatic brake control means includes a limit braking necessity determining means for determining if the possibility of collision of the vehicle with the front obstacle can be eliminated by maintaining a ratio between operations of the front and rear brakes according to the brake operation by the driver, when the collision possibility determining means determines that there is a possibility of collision, and the brake operation determining means determines that the brake operation by the driver is present;

wherein the automatic brake control means increases the braking forces of the front and rear brakes while maintaining the ratio between operations of the front and rear brakes according to the brake operation by the driver, when the limit braking necessity determining means determines that the possibility of collision with the front obstacle can be eliminated by maintaining the ratio between operations of the front and rear brakes according to the brake operation by the driver; and

wherein the automatic brake control means causes the front and rear brakes to reach a limit braking state without maintaining the ratio between operations of the front and rear brakes according to the brake operation by the driver, when the limit braking necessity determining means determines that the possibility of collision with the front obstacle cannot be eliminated by maintaining the ratio between operations of the front and rear brakes according to the brake operation by the driver.

2. The automatic brake device for a vehicle according to claim 1 ,

wherein the brake modulator includes a memory configured to store a braking force map (M) having an axis of ordinates indicating magnitude of the braking force of one of the front and rear brakes and having an axis of abscissas indicating magnitude of the braking force of the other of the front and rear brakes,

wherein a limit line (E) and a limit line (C) respectively indicating braking forces as lock limits of the front and rear brakes are described in the braking force map (M), and

wherein the automatic brake control means actuates the front and rear brakes so as to reach the limit line (E) and the limit line (C), respectively, in the braking force map (M).

3. The automatic brake device for a vehicle according to claim 2 ,

wherein the brake modulator includes friction coefficient estimating means for estimating a road surface friction coefficient,

wherein a plurality of limit lines (E) and a plurality of limit lines (C) are described according to the road surface friction coefficient, and wherein

wherein the automatic brake control means selects the limit line (E) and the limit line (C) according to the road surface friction coefficient.

4. An automatic brake device for a vehicle, the automatic brake device comprising:

a front brake;

a rear brake, wherein said front brake and rear brake are configured to be actuated independently of each other; and

an electronic control unit configured to

control actuation of the front brake and the rear brake,

determine a possibility of collision of the vehicle with a front obstacle,

perform automatic brake control which automatically increases braking forces of the front and rear brakes when the collision possibility determining unit determines that there is a possibility of a collision,

increase the braking forces of the front and rear brakes according to the brake operation by the driver, when the collision possibility determining unit determines there is a possibility of collision,

determine presence or absence of brake operation by a driver of the vehicle,

determine if the possibility of collision of the vehicle with the front obstacle can be eliminated by maintaining a ratio between operations of the front and rear brakes according to the brake operation by the driver, when the possibility of collision is determined and the brake operation by the driver is present is determined,

increase the braking forces of the front and rear brakes while maintaining the ratio between operations of the front and rear brakes according to the brake operation by the driver, when the possibility of collision with the front obstacle can be eliminated by maintaining the ratio between operations of the front and rear brakes according to the brake operation by the driver is determined, and

cause the front and rear brakes to reach a limit braking state without maintaining the ratio between operations of the front and rear brakes according to the brake operation by the driver, when the possibility of collision with the front obstacle cannot be eliminated by maintaining the ratio between operations of the front and rear brakes according to the brake operation by the driver is determined.

5. The automatic brake device for a vehicle according to claim 4 ,

wherein the electronic control unit includes a memory configured to store a braking force map (M) having an axis of ordinates indicating magnitude of the braking force of one of the front and rear brakes and having an axis of abscissas indicating magnitude of the braking force of the other of the front and rear brakes,

wherein a limit line (E) and a limit line (C) respectively indicating braking forces as lock limits of the front and rear brakes are described in the braking force map (M), and

wherein the electronic control unit is configured to actuate the front and rear brakes so as to reach the limit line (E) and the limit line (C), respectively, in the braking force map (M).

6. The automatic brake device for a vehicle according to claim 5 ,

wherein the electronic control unit is configured to estimate a road surface friction coefficient,

wherein a plurality of limit lines (E) and a plurality of limit lines (C) are described according to the road surface friction coefficient, and

wherein the electronic control unit is configured to select the limit line (E) and the limit line (C) according to the road surface friction coefficient.