Vehicle braking system having frictional and regenerative braking devices

A braking system in a motor vehicle having a plurality of wheels which include at least one drive wheel, comprising:

• a frictional braking device for forcing a friction member onto a rotor rotating with each of said plurality of wheels, to thereby apply a frictional braking torque to each of said plurality of wheels;
• a regenerative braking device including at least one electric motor which is connected to said at least one drive wheel, to apply a regenerative braking torque to said at least one drive wheel;
• and
• total braking torque control means for controlling a total braking torque applied to each of said plurality of wheels, said total braking torque including at least one of said frictional braking torque and said regenerative braking torque,
• and wherein said total braking torque control means includes
• first anti-lock control means for controlling said total braking torque applied to each of at least one slipping wheel of said plurality of wheels, so as to hold each of said at least one wheel in a substantially optimum slipping state when said total braking torque applied to each of said at least one slipping wheel has exceeded an upper limit corresponding to a friction coefficient of a road surface on which the motor vehicle is running, while one of said regenerative braking torque and said frictional braking torque of said total braking torque applied to said plurality of wheels is zero, and
• braking torque control means for controlling said total braking torques applied to said plurality of wheels when said total braking torque applied to each of said at least one slipping wheel has exceeded said upper limit while neither said regenerative braking torque nor said frictional braking torque which are applied to said plurality of wheels are zero, said braking torque control means including (1) regenerative braking torque reducing means for zeroing said regenerative braking torque, and (2) at least one of (a) second anti-lock control means for controlling said frictional braking torque of each of said at least one drive wheel whose total braking torque has exceeded said upper limit, so as to hold each of said at least one drive wheel in a substantially optimum slipping state and such that said frictional braking torque controlled by said second anti-lock control means is generally larger than said frictional braking torque controlled by said first anti-lock control means, and (b) frictional braking torque increase gradient restricting means for restricting a gradient of increase of the frictional braking torque of at least one of said plurality of wheels other than said at least one slipping wheel whose total braking torque has exceeded said upper limit.

A braking system in a motor vehicle having a plurality of wheels which include at least one drive wheel, comprising:

• a frictional braking device for forcing a friction member onto a rotor rotating with each of said plurality of wheels, to thereby apply a frictional braking torque to each of said plurality of wheels;
• first anti-lock control means for controlling said frictional braking torque applied to each of at least one slipping wheel of said plurality of wheels, so as to hold each of said at least one slippiing wheel in a substantially optimum slipping state when the frictional braking torque applied to each of said at least one slipping wheel has exceeded an upper limit corresponding to a friction coefficient of a road surface on which the motor vehicle is running;
• a regenerative braking device including at least one electric motor which is connected to said at least one drive wheel, to apply a regenerative braking torque to said at least one drive wheel;
• and
• total braking torque control means for controlling a total braking torque including at least one of said frictional braking torque and said regenerative braking torque applied to said plurality of wheels when said total braking torque applied to said at least one slipping wheel has exceeded said upper limit while neither said regenerative braking torque applied to each of said at least one slipping wheel nor said frictional braking torque applied to each of said at least one slipping wheel are zero, said total braking torque control means including (1) regenerative braking torque reducing means for zeroing said regenerative braking torque, and (2) at least one of (a) second anti-lock control means for controlling said frictional braking torque of each of said at least one drive wheel whose total braking torque has exceeded said upper limit, so as to hold said each of said at least one drive wheel in a substantially optimum slipping state and such that said frictional braking torque controlled by said second anti-lock control means is generally larger than said frictional braking torque controlled by said first anti-lock control means, and (b) frictional braking torque increase gradient restricting means for restricting a gradient of increase of the frictional braking torque of at least one of said plurality of wheels other than said at least one slipping wheel whose total braking torque has exceeded said upper limit.

A braking system in a motor vehicle having a plurality of wheels which include at least one drive wheel, comprising:

• a frictional braking device for forcing a friction member onto a rotor rotating with each of said plurality of wheels, to thereby apply a frictional braking torque to each of said plurality of wheels;
• a regenerative braking device including at least one electric motor which is connected to said at least one drive wheel, to apply a regenerative braking torque to said at least one drive wheel;
• and
• total braking torque control means for controlling a total braking torque including at least one of said regenerative braking torque and said frictional braking torque which are applied to each of said plurality of wheels, said total braking torque control means operating when the total braking torque applied to each of at least one slipping wheel of said plurality of wheels has exceeded an upper limit corresponding to a friction coefficient of a road surface on which said motor vehicle is running, for zeroing said regenerative braking torque of each of said at least one drive wheel and controlling said frictional braking torque of each of at least one of said plurality of wheels,
• wherein said total braking torque control means includes means for controlling said total braking torque of each of said at least one slipping wheel in a first anti-lock control mode when said regenerative braking torque of said at least one drive wheel is not zero, and means for controlling said frictional braking torque of each of said at least one slipping wheel in a second anti-lock control mode when said regenerative braking torque of said at least one drive wheel is zeroed;
• -said frictional braking torque of each at least one slipping drive wheel of said at least one drive wheel being controlled in said second anti-lock control mode such that a gradient of increase of said frictional braking torque is higher in said second anti-lock control mode than in said first anti-lock control mode.